Grey Correlation Analysis of Drying Characteristics and Quality of Hypsizygus marmoreus (Crab-Flavoured Mushroom) By-Products

The physical properties and nutritional quality of H. marmoreus by-products (HMB) dried by different methods were comprehensively evaluated by a rigorous statistical method of grey correlation analysis. The results indicated that different drying methods had significant impacts on the characteristics of HMB. Heat pump drying (HPD) was conducive to the preservation of protein and reducing sugar, and hot air drying (HAD) maintained a high content of total flavonoids. The highest fat, polysaccharide, and total phenolic contents were obtained by heated vacuum freeze-drying (H-VFD) treatment. The unheated vacuum freeze-drying (UH-VFD) treatment achieved bright colour, lacunose texture profile, and looser organization structure. The grey correlation analysis showed that UH-VFD and H-VFD had higher-weighted correlation degrees than HPD and HAD. HMB had many higher nutritional components than commodity specifications, especially protein, fat, polyphenols, and amino acids, and had potential applications in the food industry as functional foods and nutraceutical agents.

Comparative Evaluation of the Physiochemical Properties, and Antioxidant and Hypoglycemic Activities of Dendrobium officinale Leaves Processed Using Different Drying Techniques

Dendrobium officinale leaves have the potential to be processed into natural antioxidants, functional foods, and food additives. To maximally maintain their quality, fresh D. officinale leaves were dehydrated using different drying methods, i.e., hot air drying (HD), microwave drying (MD), infrared drying (IRD), and freeze drying (FD), and then the physicochemical properties, microstructure, and biological activities of the dried samples were compared. The results showed that, with the FD method, the samples had a porous microstructure, maintained the highest phenolic content, and demonstrated the highest antioxidant and hypoglycemic activities. Among the three thermal drying methods, with the IRD method, the samples retained higher phenolic contents, showed stronger DPPH free-radical scavenging, ferric ion reducing, ferrous ion chelating, and α-glucosidase inhibitory abilities, and more strongly promoted glucose metabolism in insulin-resistant HL-7702 cells than the samples with the MD and HD methods. These results suggested that FD was the most suitable method. However, IRD might be a promising alternative, owing to the high cost and long time needed for FD for the large-scale drying of D. officinale leaves.

Volatile Profile of Strawberry Fruits and Influence of Different Drying Methods on Their Aroma and Flavor: A Review

Strawberries are the most popular berry fruit in the world, due to their distinctive aroma, flavor, and known health properties. Because volatile substances play a large role in strawberry flavor, even little alterations can have a big impact on how the fruit tastes. Strawberries are thought to have a complex aroma. Fresh strawberry fruits contain more than 360 volatile compounds, including esters, furans, terpenes, alcohols, aldehydes, ketones, and sulfur compounds. Despite having far lower concentrations than esters, terpenoids, furanones, and sulfur compounds, all have a considerable impact on how people perceive the aroma of strawberries. With a focus on the active aroma components and the many analytical methods used to identify them, including gas chromatography, electronic nose sensing, and proton-transfer- reaction mass spectrometry, the present review's aim was to provide a summary of the relevant literature. Additionally, strawberry fruits are frequently dried to create a powder in order to increase their shelf life. Consequently, the impact of various drying techniques on strawberries' volatile profile was investigated in the current review. This review can be considered a good reference for research concerning the aroma profile of strawberries. It helps to better understand the complex aroma and flavor of strawberries and provides a guide for the effects of drying processing.

Effects of vacuum microwave combined with freeze-drying on the physicochemical properties, phenolic compounds, and antioxidant capacity of pear fruit slices

The effects of freeze-drying (FD), vacuum microwave drying after freeze-drying (FD-VMD), and freeze-drying after vacuum microwave drying (VMD-FD) on the physicochemical properties, phenolic compounds, and antioxidant capacity of pear fruit slices were investigated. The results showed that FD samples had the highest crispness value (116.30 N·sec) and the lowest volume shrinkage ratio value (5.48%). Compared to FD, the VMD-FD and FD-VMD methods could save drying time without affecting the color of dried samples. FD-VMD samples had the lowest rehydration capacity and maintained a homogeneous porous structure, while the VMD-FD samples had obvious collapse. Compared to VMD-FD samples, FD-VMD samples had higher contents of ascorbic acid (20.91 mg/100 g), total phenolic (7.62 mg/g), total anthocyanin (0.21 mg/g), and gallic acid (1.21 µg/g). Moreover, FD-VMD samples showed the highest antioxidant capacity as evaluated by the 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging capacity, and H₂ O₂ content. Compared with FD and VMD-FD, FD-VMD was most effective in maintaining better quality and shortening drying time of pear fruit slices. These findings suggested that FD-VMD might be a promising drying technique in the fruits and vegetable processing industries.

The Nutrients and Volatile Compounds in Stropharia rugoso-annulata by Three Drying Treatments

This study aimed to examine the differences in the nutrients and volatile compounds of Stropharia rugoso-annulata after undergoing three different drying treatments. The fresh mushrooms were dried using hot air drying (HAD), vacuum freeze drying (VFD), and natural air drying (NAD), respectively. After that, the nutrients, volatile components, and sensory evaluation of the treated mushrooms were comparably analyzed. Nutrients analysis included proximate compositions, free amino acids, fatty acids, mineral elements, bioactive compositions, and antioxidant activity. Volatile components were identified by headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and analyzed with principal component analysis (PCA). Finally, sensory evaluation was conducted by ten volunteers for five sensory properties. The results showed that the HAD group had the highest vitamin D₂ content (4.00 μg/g) and antioxidant activity. Compared with other treatments, the VFD group had higher overall nutrient contents, as well as being more preferred by consumers. Additionally, there were 79 volatile compounds identified by HS-SPME-GC-MS, while the NAD group showed the highest contents of volatile compounds (1931.75 μg/g) and volatile flavor compounds (1307.21 μg/g). PCA analysis suggested the volatile flavor compositions were different among the three groups. In summary, it is recommended that one uses VFD for obtaining higher overall nutritional values, while NAD treatment increased the production of volatile flavor components of the mushroom.

Evaluation of the antioxidant, anti-inflammatory, and anti-tumoral properties of bioactive compounds extracted from murta berries (Ugni molinae T.) dried by different methods

This study evaluated the effects of different drying methods (freeze drying, vacuum drying, infrared drying, convective drying, and sun drying) on the biological properties of berries from the Chilean murta (Ugni molinae Turcz) shrub. Physical-chemical properties (proximal composition, dietary fiber, sugars) were determined. Total phenolic content through the method of Folin-Ciocalteau, the profile of phenol compounds was determined by HPLC, and antioxidant potential by DPPH and ORAC assays were also evaluated. The topic anti-inflammatory effect was evaluated by mice´s ear edema, and in vitro anti-tumoral activity was tested by MTT assay. The chemical properties of dried berries differed significantly based on the drying method: freeze-dried murta berries showed increased total phenolic content extracted over fresh and dried samples. In addition, this lyophilized extract stood out in its antioxidant potential, in both assays evaluated (DPPH and ORAC), compared to the other drying methods. Notwithstanding, vacuum- and infrared-dried murta also showed a higher ORAC value. Antioxidant potential was significantly associated with phenolic compounds catechin and pyrogallol, which were the most abundant phenolic compounds present in all samples. The anti-inflammatory activity was most effective under freeze-drying and vacuumdrying conditions. Moreover, vacuum drying and infrared drying best preserved the anti-tumoral effect on cancer cells.

Three-Dimensional Appearance and Physicochemical Properties of Pleurotus eryngii under Different Drying Methods

This study investigated the effects of different drying methods on the drying characteristics, three-dimensional (3D) appearance, color, total polysaccharide content (TPC), antioxidant activity, and microstructure of Pleurotus eryngii slices. The drying methods included hot air drying (HAD), infrared drying (ID), and microwave drying (MD). The results showed that the drying method and conditions significantly influenced the drying time, with MD having a significant advantage in reducing the drying time. The 3D appearance of P. eryngii slices was evaluated based on shrinkage and roughness as quantitative indexes, and the best appearance was obtained by hot air drying at 55 and 65 °C. HAD and ID at lower drying temperatures obtained better color, TPC, and antioxidant activity, but MD significantly damaged the color and nutritional quality of P. eryngii. The microstructure of dried P. eryngii slices was observed using scanning electron microscopy, and the results showed that drying methods and conditions had an obvious effect on the microstructure of P. eryngii slices. Scattered mycelia were clearly observed in P. eryngii samples dried by HAD and ID at lower drying temperatures, while high drying temperatures led to the cross-linking and aggregation of mycelia. This study offers scientific and technical support for choosing appropriate drying methods to achieve a desirable appearance and quality of dried P. eryngii.

Effects of Different Drying Methods on Drying Characteristics and Quality of Glycyrrhiza uralensis (Licorice)

Large amounts of waste result from licorice mold rot; moreover, prompt drying directly influences product quality and value. This study compared various glycyrrhiza drying methods (Hot air drying (HAD), infrared combined hot air drying (IR-HAD), vacuum freeze drying (VFD), microwave vacuum drying (MVD), and vacuum pulsation drying (VPD)) that are used in the processing of traditional Chinese medicine. To investigate the effects of various drying methods on the drying characteristics and internal quality of licorice slices, their color, browning, total phenol, total flavonoid, and active components (liquiritin and glycyrrhizic acid) were chosen as qualitative and quantitative evaluation indices. Our results revealed that VFD had the longest drying time, but it could effectively maintain the contents of total phenol, total flavonoid, and liquiritin and glycyrrhizic acid. The results also showed that VFD samples had the best color and the lowest degree of browning, followed by HAD, IR-HAD, and VPD. We think that VFD is the best approach to ensure that licorice is dry.

Effects of Different Drying Methods on the Selenium Bioaccessibility and Antioxidant Activity of Cardamine violifolia

Understanding the effects of drying on the selenium (Se) content and Se bioaccessibility of Se-rich plants is critical to dietary supplementation of Se. The effects of five common drying methods (far-infrared drying (FIRD), vacuum drying (VD), microwave vacuum drying (MVD), hot air drying (HD), and freeze vacuum drying (FD)) on the content and bioaccessibility of Se and Se species in Cardamine violifolia leaves (CVLs) were studied. The content of SeCys₂ in fresh CVLs was the highest (5060.50 μg/g of dry weight (DW)); after FIRD, it had the lowest selenium loss, with a loss rate of less than 19%. Among all of the drying processes, FD and VD samples had the lowest Se retention and bioaccessibility. FIRD, VD, and FD samples have similar effects on antioxidant activity.

Effect of Different Drying Methods on the Quality and Nonvolatile Flavor Components of Oudemansiella raphanipes

Different drying methods affect the quality of foods. The aim of this study is to explore the effects of seven drying methods, including hot air drying at 60 °C and 80 °C, ultrasound-assisted hot air drying at 60 °C and 80 °C, microwave drying, vacuum microwave drying, and vacuum freeze-drying, on the quality and nonvolatile flavor components of Oudemansiella raphanipes. The vacuum freeze-drying resulted in minimal collapse, mild shrinkage at the macroscopic level, and the formation of uniform pores at the microscopic level on the surfaces of O. raphanipes mushrooms. In addition, vacuum freeze-drying can improve the color attributes of the mushrooms. Therefore, the appearance and shape of vacuum freeze-drying treated O. raphanipes were closest to those of fresh mushrooms. We found that ultrasound-assisted treatment can effectively shorten the drying time of O. raphanipes. The drying time of ultrasound-assisted hot air drying at 60 °C was 20% shorter than that of hot air drying at 60 °C, and the drying time of ultrasound-assisted hot air drying at 80 °C was 37.5% shorter than that of hot air drying at 80 °C. The analysis of the nonvolatile flavor components showed that the ultrasound-assisted hot air drying at 60 °C of the O. raphanipes sample had the highest content of free amino acids (83.78 mg/g) and an equivalent umami concentration value (1491.33 monosodium glutamate/100 g). The vacuum freeze-drying treated O. raphanipes had the highest 5'-nucleotide content of 2.44 mg/g. Therefore, vacuum freeze-drying and ultrasound-assisted hot air drying at 60 °C, followed by vacuum microwave drying, might protect the flavor components of O. raphanipes to the greatest extent. However, microwave drying, hot air drying at 80 °C, and ultrasound-assisted hot air drying at 80 °C could destroy the flavor components of O. raphanipes during drying. The results of this study provided data support for the industrial production of dried O. raphanipes.

Effects of Drying Methods on Taste Components and Flavor Characterization of Cordyceps militaris

The influences of four drying methods (hot air drying (HAD), vacuum freeze drying (VFD), vacuum drying (VD) and intermittent microwave combined with hot air drying (MW-HAD)) on the taste profile and flavor characteristic of Cordyceps militaris were investigated. MW-HAD samples had the highest levels of umami taste 5'-nucleotides, bitter taste amino acids, and equivalent umami concentration (EUC) value. The aroma fingerprints and differences of dried Cordyceps militaris were established by GC-MS with odor activity values (OAVs) and GC-IMS with principal component analysis (PCA). GC-MS data showed that the predominant volatiles of dried samples were aldehydes, alcohols, and ketones. VFD samples had the highest amount of total aroma compounds and C8 compounds. Moreover, 21 aroma-active components (OAVs ≥ 1) were the main contributors to the flavor of dried Cordyceps militaris. The OAVs of 1-octen-3-one and 3-octanone associated with mushroom-like odor in VFD were significantly higher than other samples. Furthermore, a significant difference in flavor compounds of four dried samples was also clearly demonstrated by GC-IMS analysis with PCA. GC-IMS analysis revealed that VFD samples had the most abundant flavor compounds. Overall, MW-HAD was an effective drying method to promote umami taste, and VFD could superiorly preserve volatiles and characteristic aroma compounds in dried Cordyceps militaris.

Ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry based untargeted metabolomics to reveal the characteristics of Dictyophora rubrovolvata from different drying methods

Dictyophora rubrovolvata is a highly valuable and economically important edible fungus whose nutrition and flavor components may vary based on drying methods. Herein, an untargeted ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) metabolomics method combined with multivariate analysis was first performed to characterize the metabolomics profiles of D. rubrovolvata upon different drying treatments, viz., coal burning drying (CD), electrothermal hot air drying (ED), and freeze drying (FD). The results indicated that 69 differential metabolites were identified, vastly involving lipids, amino acids, nucleotides, organic acids, carbohydrates, and their derivatives, of which 13 compounds were confirmed as biomarkers in response to diverse drying treatments. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis illustrated that differential metabolites were significantly assigned to 59, 55, and 60 pathways of CD vs. ED, CD vs. FD, and FD vs. ED groups, respectively, with 9 of the top 20 KEGG pathways shared. Specifically, most of lipids, such as fatty acyls, glycerophospholipids and sphingolipids, achieved the highest levels in D. rubrovolvata after the CD treatment. ED method substantially enhanced the contents of sterol lipids, nucleotides, organic acids and carbohydrates, while the levels of amino acids, prenol lipids and glycerolipids were elevated dramatically against the FD treatment. Collectively, this study shed light on metabolomic profiles and proposed biomarkers of D. rubrovolvata subjected to multiple drying techniques, which may contribute to quality control and drying efficiency in edible fungi production.

[Effects of different drying methods on ginsenosides based on UHPLC-Q-Exactive Orbitrap MS technique]

The present study quickly identified the ginsenosides in fresh Panax ginseng and specified the effects of different drying methods(50 ℃-drying, 80 ℃-drying, and-70 ℃ freeze-drying) on ginsenosides.Three P.ginseng products by different drying methods were prepared, and the UHPLC-Q-Exactive Orbitrap high-resolution liquid mass spectrometry(MS) technique was applied to perform gradient elution using water-acetonitrile as the mobile phase, and the data collected in the negative ion mode were analyzed using X Calibur 2.2.The results showed that 57 saponins were identified from fresh P.ginseng.As revealed by the comparison with the fresh P.ginseng, in terms of the loss of ginsenosides, the dried products were ranked as the dried product at 50 ℃, freeze-dried products at-70 ℃, and the dried product at 80 ℃ in the ascending order.This study elucidated the effects of different drying methods on the types and relative content of ginsenosides, which can provide references for the processing of P.ginseng in the producing areas.

The Effects of Drying Techniques on Phytochemical Contents and Biological Activities on Selected Bamboo Leaves

The therapeutic potential of bamboos has acquired global attention. Nonetheless, the biological activities of the plants are rarely considered due to limited available references in Sabah, Malaysia. Furthermore, the drying technique could significantly affect the retention and degradation of nutrients in bamboos. Consequently, the current study investigated five drying methods, namely, sun, shade, microwave, oven, and freeze-drying, of the leaves of six bamboo species, Bambusa multiplex, Bambusa tuldoides, Bambusa vulgaris, Dinochloa sublaevigata, Gigantochloa levis, and Schizostachyum brachycladum. The infused bamboo leaves extracts were analysed for their total phenolic content (TPC) and total flavonoid content (TFC). The antioxidant activities of the samples were determined via the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) assays, whereas their toxicities were evaluated through the brine shrimp lethality assay (BSLA). The chemical constituents of the samples were determined using liquid chromatography−tandem mass spectrometry (LC-MS/MS). The freeze-drying method exhibited the highest phytochemical contents and antioxidant activity yield, excluding the B. vulgaris sample, in which the microwave-dried sample recorded the most antioxidant and phytochemical levels. The TPC and TFC results were within the 2.69 ± 0.01−12.59 ± 0.09 mg gallic acid equivalent (GAE)/g and 0.77 ± 0.01−2.12 ± 0.01 mg quercetin equivalent (QE)/g ranges, respectively. The DPPH and ABTS IC50 (half-maximal inhibitory concentration) were 2.92 ± 0.01−4.73 ± 0.02 and 1.89−0.01 to 3.47 ± 0.00 µg/mL, respectively, indicating high radical scavenging activities. The FRAP values differed significantly between the drying methods, within the 6.40 ± 0.12−36.65 ± 0.09 mg Trolox equivalent (TE)/g range. The phytochemical contents and antioxidant capacities exhibited a moderate correlation, revealing that the TPC and TFC were slightly responsible for the antioxidant activities. The toxicity assessment of the bamboo extracts in the current study demonstrated no toxicity against the BSLA based on the LC50 (lethal concentration 50) analysis at >1000 µg/mL. LC-MS analysis showed that alkaloid and pharmaceutical compounds influence antioxidant activities, as found in previous studies. The acquired information might aid in the development of bamboo leaves as functional food items, such as bamboo tea. They could also be investigated for their medicinal ingredients that can be used in the discovery of potential drugs.

leaves: a comparative study

This comparative study aimed to evaluate the effects of different drying methods such as solar drying, shade drying (SHD), freeze drying (FD), oven drying, and microwave drying on the physicochemical properties, bioactive components, and antioxidant activity of Centella asiatica. The results showed that out of all the treated samples, FD-treated samples showed the lowest moisture content (2.4%), the lowest water activity (0.24%), and the highest rehydration ratio (5.51%). For samples treated using different drying methods, significant differences in Commission on Illumination - LAB (L *, a *, and b *) values and total color difference (E ) were observed. FD-treated samples showed the minimum color change (E ) and highest lightness (L *). Additionally, upon Fourier-transform infrared spectral analysis, no major changes in the functional groups were observed between C. asiatica leaves processed using different drying methods. FD-treated samples showed the highest antioxidant activity followed by SHD-treated samples, as measured by 2,2-diphenyl-1-picrylhydrazyl and 2,2-azino-bis-3-ethylbenzo-thiazoline-6-sulphonic acid radical scavenging assays. The phenolic (chlorogenic acid, rutin, kaempferol, and quercetin) and triterpene saponin (madecassoside, asiaticoside, madecassic acid, and asiatic acid) contents of the dried samples of C. asiatica were measured using high-performance liquid chromatography, which showed that the FD method allowed for the highest retention of phenolic and triterpene saponins among the tested drying techniques. The physicochemical characteristics, antioxidant potential, and bioactive retention of the samples that underwent FD treatment were superior to those of other methods, and therefore, FD can be employed as the first-line drying technique for processing C. asiatica leaves.

Comparison of Different Drying Methods on the Volatile Components of Ginger (Zingiber officinale Roscoe) by HS-GC-MS Coupled with Fast GC E-Nose

Ginger (Zingiber officinale Roscoe) is one of the most popular spices in the world, with its unique odor. Due to its health benefits, ginger is also widely used as a dietary supplement and herbal medicine. In this study, the main flavor components of gingers processed by different drying methods including hot air drying, vacuum drying, sun-drying, and vacuum-freeze drying, were identified on the basis of headspace-gas chromatography coupled with mass spectrometry (HS-GC-MS) and fast gas chromatography electronic-nose (fast GC e-nose) techniques. The results showed that the ginger dried by hot air drying exhibited high contents of volatile compounds and retained the richest odor in comparison with those dried by other methods, which indicated that hot air drying is more suitable for the production of dried ginger. Sensory description by fast GC e-nose exhibited that ginger flavor was mainly concentrated in the spicy, sweet, minty, fruity, and herbaceous odor. The relative content of the zingiberene was significantly higher in the hot air drying sample than those by other methods, suggesting that dried ginger by hot air drying can retain more unique spicy and pungent odorants. Furthermore, the results of chemometrics analyses showed that the main variance components among the samples by different drying methods were α-naginatene, (+)-cyclosativene, and sulcatone in HS-GC-MS analysis, and α-terpinen-7-al, dimethyl sulfide, and citronellal in fast GC e-nose analysis. For comparison of fresh and dried gingers, terpinolene, terpinen-4-ol, 2,4-decadienal, (E, Z)-, and linalool were considered the main variance components. This study generated a better understanding of the flavor characteristics of gingers by different drying methods and could provide a guide for drying and processing of ginger.

Production of Bovine Colostrum for Human Consumption to Improve Health

Colostrum contains all essential nutrients for the neonate during the first days of life, with impacts that continue far beyond these first days. Bovine colostrum has been used for human consumption due to the high concentrations of bioactive proteins, vitamins, minerals, growth factors, as well as free and conjugated oligosaccharides. Processes involved in the preparation of bovine colostrum for human consumption play a pivotal role in preserving and maintaining the activity of the bioactive molecules. As bovine colostrum is a multifunctional food that offers a myriad of benefits for human health, assessing the main processes used in preparing it with both advantages and disadvantages is a crucial point to discuss. We discuss major processes effects for colostrum production on the nutritional value, some advanced technologies to preserve processed bovine colostrum and the end-product forms consumed by humans whether as dairy products or dietary supplements.

Effects of Drying Process on the Volatile and Non-Volatile Flavor Compounds of Lentinula edodes

In this study, fresh Lentinula edodes was dehydrated using freeze-drying (FD), hot-air drying (HAD), and natural drying (ND), and the volatile and non-volatile flavor compounds were analyzed. The drying process changed the contents of eight-carbon compounds and resulted in a weaker “mushroom flavor” for dried L. edodes. HAD mushrooms had higher levels of cyclic sulfur compounds (56.55 μg/g) and showed a stronger typical shiitake mushroom aroma than those of fresh (7.24 μg/g), ND (0.04 μg/g), and FD mushrooms (3.90 μg/g). The levels of 5′-nucleotide increased, whereas the levels of organic acids and free amino acids decreased after the drying process. The dried L. edodes treated with FD had the lowest levels of total free amino acids (29.13 mg/g). However, it had the highest levels of umami taste amino acids (3.97 mg/g), bitter taste amino acids (6.28 mg/g) and equivalent umami concentration (EUC) value (29.88 g monosodium glutamate (MSG) per 100 g). The results indicated that FD was an effective drying method to produce umami flavor in dried mushrooms. Meanwhile, HAD can be used to produce a typical shiitake mushroom aroma. Our results provide a theoretical basis to manufacture L. edodes products with a desirable flavor for daily cuisine or in a processed form.

Metabolomics Provides A Novel Interpretation of the Changes in Main Compounds during Black Tea Processing through Different Drying Methods

This study aimed to compare the effect of hot roller (HR) drying and hot air (HA) drying on the sensory evaluation, chemical quality, antioxidant activity, and metabolic profile of Yihong Congou black tea processed from E’cha NO1. The Yihong Congou black tea dried with HA obtained higher sensory scores and better chemical qualities such as the hue of tea brew color (a and b), content of theaflavins, thearubigins, water extract, free amino acids, tea polyphenol, and the ratio of polyphenol to amino acids as well as higher antioxidant capacities compared to that dried with HR. The HA drying tea increased the contents of volatile compounds that had positive correlation with sweet and flowery flavor, while the HR drying tea increased the contents of volatile compounds related to fruity flavor. Moreover, non-targeted metabolomics data indicated that the levels of most free amino acids significantly increased, while the levels of most soluble sugars reduced in the HA drying method compared to the HR drying method. The metabolic analysis was also consistent with the above results and revealed that D-ribose and gallic acid were the main characteristic metabolites of HA drying. Our results could provide a technical reference and theoretical guide to processing a high quality of Yihong Congou black tea.

Composition Changes in Lycium ruthenicum Fruit Dried by Different Methods

The fruit of Lycium ruthenicum (LRF), known as black wolfberry, is a medicinal and edible fruit. The fresh LRF is perishable and has only about 3 days of shelf life. Drying could prolong the shelf life of LRF. However, it could imply physical changes and chemical modification. This study evaluated the effect of sun drying (SD), hot air drying (HD), and freeze drying (FD) on the appearance characteristics, moisture content, bioactive compounds, amino acid composition, and antioxidant activity of LRF. The results showed that LRF dried by FD was round, expansive, fragile, and maintained the largest amount of appearance traits among the three drying methods. Drying methods had a significant effect on phytochemical content and antioxidant activity of LRF (P < 0.05). Principal component analysis (PCA) showed that procyanidin content (PAC), asparagine (Asn), total phenolic content (TPC), total anthocyanin content (TAC), and moisture content were the main sources of the difference in LRF dried by different methods. The characteristic of LRF in FD was low moisture content, and high TPC, Asn, PAC, and TAC. Sun drying was opposite to FD. Hot air drying was high TPC and low TAC content. The quality of LRF was in the order of FD > HD > SD based on comprehensive evaluation of the phytochemical component content and antioxidant capacity. Additionally, the water temperature and soaking time had different antioxidant activity effect on LRF dried by different methods. These findings will provide useful information for production and utilization of LRF.

Flavonoid Levels and Antioxidant Capacity of Mulberry Leaves: Effects of Growth Period and Drying Methods

In recent years, various mulberry leaf dishes have gradually gained in popularity. The harvesting period of mulberry leaves and the preparation of dried samples are critical for the retention of flavonoid content and activity. In this study, changes in flavonoid levels in mulberry leaves during their growth period (3-6 months), and the effects of four different drying methods [sun drying (SD), air drying (AD), oven drying (OD), and freeze drying (FD)] on flavonoid accumulation and antioxidant capacity were determined. The results showed that mulberry leaves grown for 6 months had higher levels of flavonoids, and different drying methods could significantly affect the flavonoid levels and antioxidant capacity of the leaves. Air drying and FD were the best methods in terms of retaining the antioxidant activity of flavonoids, although AD had lower operating costs than FD in the production process. Therefore, to obtain a high flavonoid content and maximum antioxidant activity, AD is recommended for mulberry leaves.

Influence of Freezing and Different Drying Methods on Volatile Profiles of Strawberry and Analysis of Volatile Compounds of Strawberry Commercial Jams

Strawberry is the most consumed berry fruit worldwide due to its unique aroma and flavor. Drying fruits to produce a powder represents one of the possible conservation methods to extend their shelf-life. The aim of the present study was to compare the influence of freezing and different drying methods on the volatile profile of strawberry using the HS-SPME/GC–MS method, in addition to analysis of strawberry jam volatiles. A total of 165 compounds were identified, accounting for 85.03–96.88% of the total volatile compositions. Results and PCA showed that freezing and each drying process affected the volatile profile in a different way, and the most remarkable representative differential volatiles were ethyl hexanoate, hexyl acetate, (E)-2-hexenyl acetate, mesifurane, (E)-nerolidol, γ-decalactone, 1-hexanol, and acetoin. Shade air-dried, frozen, freeze-dried, and oven-dried 45 °C samples retained more of the fruity and sweet aromas of strawberry, representing more than 68% of the total aroma intensity according to the literature. In contrast, the microwave-drying method showed drastic loss of fruity esters. Strawberry jams demonstrated complete destruction of esters and alcohols in most jams, while terpenes were significantly increased. These findings help better understand the aroma of strawberry and provide a guide for the effects of drying, freezing, and jam processing.

Variation in the Physical and Functional Properties of Yam (Dioscorea spp.) Flour Produced by Different Processing Techniques

Research on the processing of yam (Dioscorea spp.) into flour is aimed at optimizing techniques to obtain a material with high physicochemical and functional properties. The present study investigates the effect of the processing techniques on the levels of inulin, organic acids, total phenolics (TP), antioxidant capacity, and polyphenol oxidase (PPO) and peroxidase (POD) activities, as well as on the physicochemical properties of flour derived from two yam species-Dioscorea esculenta and Dioscorea bulbifera. All tubers were peeled and sliced, then subjected to different processing techniques through blanching, soaking, and drying. The results revealed that freeze-drying appears to be the best technique in achieving the highest whiteness index of yam flour. This coincided well with the low phenolics content and POD activity, which suggests a reduced enzymatic browning reaction in the freeze-dried yam flour. On the other hand, chemical analyses showed that D. esculenta and D. bulbifera flours have the highest levels of inulin (23.0 and 27.8 g/100 g DW, respectively) and succinic acid (7.96 and 7.65 g/100 g DW, respectively) in the samples subjected to direct oven-drying. Oven drying without pretreatment neither blanching nor water steeping maintained antioxidant activity in the flour derived from both D. esculenta and D. bulbifera.

Effect of Drying Methods on Volatile Compounds of Burdock (Arctium lappa L.) Root Tea as Revealed by Gas Chromatography Mass Spectrometry-Based Metabolomics

Burdock (Arctium lappa L.) is one of the nutritional foods widely planted in many countries. Dried burdock root (BR) is available as a herbal tincture and tea in many Asian countries with good flavor and taste. In this study, the volatile components in dried BR were identified and the effects of different drying methods on the volatile components were investigated by HS-GC-MS method. A total of 49 compounds were identified. Different drying methods including hot-air drying (HD, at 50, 60, 70, and 80 °C), vacuum drying (VD, at 50, 60, 70, and 80 °C), sunlight drying (SD), natural drying (ND), and vacuum freeze drying (VFD) were evaluated by HS-GC-MS-based metabolomics method. Results showed that different drying methods produced different effects on the volatile compounds. It was observed that 2,3-pentanedione, 1-(1H-pyrrol-2-yl)-ethanone, furfural, and heptanal were detected at higher concentrations in HD 80 and VD 70. The traditional HD and SD methods produced more flavor substances than VFD. The BR treated by the VFD method could maintain the shape of the fresh BR pieces while HD50 and VD80 methods could maintain the color of fresh BR pieces. These findings could help better understand the flavor of the corresponding processed BR and provide a guide for the drying and processing of BR tea.

Comparison of hydrability, antioxidants, microstructure, and sensory quality of barley grass powder using ultra-micro-crushing combined with hot air and freeze drying

To explore the physicochemical characters of barley grass, ultra-micro-crushing (UMC) technology combined with air drying or freeze drying was carried out. After barley grass was air-dried at 70°C or freeze-dried at 15°C, it was grinded for 30, 60, 90, and 120 min using UMC, respectively. After combined processing, moisture content, particle size, odor, color, microstructure, water and oil-holding capacity, the content of flavonoid and chlorophyll, water activity, and sensory qualities were determined. The particle size of barley grass powder decreased, and lightness value was increased; water and oil-holding capacity decreased significantly (p ≤ .05), whereas swelling and dissolving capacity increased in the processed grass powder. On the other hand, the total flavonoid content increased significantly (p ≤ .05). Barley grass odor features sulfide aroma, and its microstructure demonstrates lamellar morphology with some fewer fragmented pieces. The results suggested combined UMC at 90-120 min will be suitable for processing barley grass powder.

Physical and chemical characteristics of Asian sea bass bio-calcium powders as affected by ultrasonication treatment and drying method

The effects of ultrasonication and drying method on particle size and other product characteristics of bio-calcium powder from Asian sea bass (Lates calcarifer) backbone were investigated. Ultrasonication was performed at different amplitudes (60%, 70%, and 80%) for varying periods (15 and 30 min). Ultrasonication at higher amplitudes for a longer time reduced the powder particle size more effectively (p < .05), but had no impact on zeta potential (p > .05). The bio-calcium powder ultrasonicated at 70% amplitude for 15 min had the smallest particle size (3.38 µm) when compared to the control (28.85 µm). When the ultrasonicated bio-calcium was subjected to drying, freeze-drying produced powders with higher calcium solubility but lower whiteness than hot air (tray) drying. The results suggest that the ultrasonication is a potential suitable method to reduce the size of bio-calcium powders, while the drying method slightly affected the product characteristics. The bio-calcium powder could serve as a suitable functional ingredient for food fortification aimed at improving the calcium bioavailability. Particle size of bio-calcium powder from fishbone could affect the mouth feel and calcium solubility when used for food product fortification. This work showed that ultrasonication could be used to obtain up to 10-fold reduction in the particle size of fishbone bio-calcium powders, which promotes increased calcium solubility when subjected to simulated gastrointestinal tract digestion. Few differences in characteristics of the bio-calcium powder were observed for freeze-dried and hot air-dried samples. Thus, an economical, safe, and fast process can be implemented for the production of small particle size bio-calcium powder from fishbone.

Assessment of Chokeberry Powders Quality Obtained Using an Innovative Fluidized-Bed Jet Milling and Drying Method with Pre-Drying Compared with Convection Drying

There is a need and great interest among food producers in obtaining powders from fruit and vegetables of both high nutritional value and sensory qualities superior to those hitherto obtained by convection drying (CD) and spray drying methods and cheaper to prepare than the sublimation method. This study is focused on whether powders can be obtained from fruit berries with a sticky structure, using the chokeberry (Aronia melanocarpa) as a test example, by a combined fluidized-bed jet milling and drying (FBJD) of pre-dried fruit by CD to an adequate water activity (a_w). The pre-drying step reduced sticking between fruit particles during the simultaneous drying and grinding processes of the FBJD method in order to obtain powders of desired granulation. Three different pre-drying temperatures of 50, 60, and 70 °C were tested for levels of microorganisms in chokeberries at a water activity of 0.4. Vitamin C content and antioxidant properties were also examined along with polyphenol separation. Fruit pre-dried at 60-70 °C had significantly higher vitamin C and polyphenolic content and greater antioxidant properties than those pre-dried at 50 °C. Further studies were thus undertaken on powders pre-dried at 70 °C in which antioxidant properties, vitamin C, and polyphenols content were also compared with CD obtained powders. The FBJD method combined with CD pre-drying proved superior to just using the CD method, where powders had a greater preservation of vitamin C at 84% (CD powders 35%), a 12% higher total polyphenol content, and a 10% higher antioxidant activity. The test method also uses a much shorter drying time than the CD method, because the grinding of the hard-textured material takes only few minutes.

based on UHPLC-MS analysis and antidepressant activity of the main chemical component regaloside A

The Lilium lancifolium Thunb. is a herb with multiple functions in both medicine and food in China, and its extracts have shown antidepressant effects. In this study, fresh bulbs of Lilium lancifolium Thunb. were processed to study the effects of different drying processes on changes in its main chemical components. We found that different drying methods can affect the chemical constituents of the herb. Among these components, Regaloside A has been found as the characteristic component. Here, Cell Counting Kit-8 assay, and Western blotting were used to evaluate the neuroprotective antidepressant effects of Regaloside A. The results showed the cell survival rate was improved, the phosphorylation levels of brain-derived neurotrophic factor, tyrosine kinase receptor B, phosphatidylinositol 3 kinase, protein kinase B, and mammalian target of rapamycin were increased after Regaloside A treatment. In general, different drying methods have a significant influence on the chemical composition of the herb, and Regaloside A may be the main chemical component of the herb. It can alleviate the damage of corticosterone in SH-SY5Y cells, and phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin signaling mediated by brain-derived neurotrophic factor/tyrosine kinase receptor B may play an important role in the neuroprotective antidepressant effects of Regaloside A.

Effects of different drying methods on the structures and functional properties of phosphorylated Antarctic krill protein

Antarctic krill protein (AKP) was extracted from Antarctic krill by an alkali dissolution-isoelectric precipitation method and then it was phosphorylated with sodium tripolyphosphate. The phosphorylated Antarctic krill protein (P-AKP) powder was obtained by spray-drying (SD), freeze-drying (FD), and hot-air drying (AD), and the effects of these drying methods on the structures and functional properties of proteins were investigated. The P-AKP powder dried by SD had the best sensory performance, and its particle size was much smaller than that of FD and AD. Scanning electron microscope displayed a uniform particle size of SD powder and the particles were uniformly dispersed. X-ray diffraction analysis showed a higher crystallinity of SD sample than AD and FD. Differential scanning calorimeter analysis revealed that SD sample had the best thermal stability and less protein denaturation (ΔH = 210.80 J/g), followed by FD (ΔH = 80.48 J/g) and AD (ΔH = 73.94 J/g; P < 0.05). Fourier transform infrared showed that SD sample contained more protein secondary structure. Compared with SD, the phosphorylated group-related chemical bonds in FD and AD samples were partially destroyed. SD sample had the highest protein solubility, oil absorption capacity, emulsifying, and foaming activities than FD and AD (P < 0.05). Although FD had the highest water absorption capacity, sample prepared with AD had the worst functional performance. Therefore, different drying methods used for preparation of the P-AKP can affect its physicochemical and associated functional properties, and SD could be an appropriate drying method for the industrial mass production of P-AKP powders with better functionalities. PRACTICAL APPLICATION: The optimal drying method for preparing the phosphorylated Antarctic krill protein (P-AKP) powder was proved to be spray-drying (SD), because the physicochemical and functional properties were better for P-AKP dried by SD than the other drying methods. Hence, SD was recommended for the industrial mass production of P-AKP powders with better functionalities. This research can provide theoretical guidance for the further processing and utilization of P-AKP, and offer technical reference for food processing and preservation.

Volumetric Analysis of Root Canal Filling in Deciduous Teeth after Using Different Canal-Drying Methods: An In-vitro Study

Background:

Drying the root canals in pulp therapy is often ignored, but is essential for a successful clinical outcome. The conventional method used for drying root canals is by the use of paper points, but recently, various other methods have also been employed for this purpose.

Aim:

The purpose of this study was to volumetrically analyze root canal fillings in deciduous teeth, after using different canal-drying methods namely 95% ethanol, CANAL CLEAN (Cerkamed Medical Company), and Endo-Aspirator (Cerkamed Medical Company), and compare with the conventional paper point drying method.

Methodology:

Access cavities were prepared on eighty extracted primary canines, and irrigation was done with 1% sodium hypochlorite and normal saline while enlarging the canals. The specimens were then scanned using a cone-beam computed tomography (CBCT), and preobturation volume (X) of each tooth was measured. The teeth were then randomly divided into two groups – Group 1 – Zinc oxide eugenol (ZOE) group and Group 2 – Metapex group. Each group was further divided randomly into four subgroups based on the drying agent used – Subgroup A – Control group, Subgroup B – 95% ethanol group, Subgroup C – CANAL CLEAN group, and Subgroup D – Endo-Aspirator group. After obturation, a second CBCT was taken to measure the postobturation volume (Y). The percentage of obturated volume was calculated by the following formula: (postobturation volume/preobturation volume) ×100 ([Y/X] ×100).

Statistical Analysis:

The obtained data were tabulated and subjected to statistical analysis using one-way ANOVA test and unpaired t-test.

Results:

A significantly high postobturation volume was seen after using 95% ethanol followed by CANAL CLEAN, Endo-Aspirator, and paper points. On comparing the obturation volumes within Metapex and ZOE groups, Metapex group had significantly high obturation volumes irrespective of the drying method used.

Conclusion:

95% ethanol is the best intracanal drying agent as it provides optimum pupal obturation.

Volatile Composition and Sensory Properties as Quality Attributes of Fresh and Dried Hemp Flowers (Cannabis sativa L.)

Flowers of hemp (Cannabis sativa L.) are widely used in cosmetics, food, and in the pharmaceutical industry. The drying process plays a key role in retention of aroma and also in the quality of products. Seven variants of hemp flower drying, including convection drying (CD), vacuum–microwave drying (VMD), and combined drying consisting of convective pre-drying followed by vacuum–microwave finishing drying (CPD-VMFD) were checked in this study. For each process, we applied the two-term model. Dried material was submitted to color and chromatographical assessments. Analyses of obtained essential oil showed the presence of 93 volatile compounds, predominantly β-myrcene, limonene, and β-(E)-caryophyllene, as well as α-humulene. Application of 240 W during VMD and 50 °C during CD gave the highest retention of aroma compounds, amounting to 85 and 76%, respectively, but with huge color changes. Additionally, sensory analysis proved that drying with a microwave power of 240 W provides a product most similar to fresh material.

subtilis-fermented polished adlay subjected to different drying methods

The physicochemical properties and antioxidant activity of B. subtilis-fermented polished adlay (BPA) subjected to different drying methods (hot-air drying, HAD; infrared-radiation drying, IRD; vacuum drying, VD; microwave-vacuum drying, MVD; and freeze-vacuum drying, FVD) were evaluated in this study. Results showed FVD was ideal for maintaining the natural appearance and higher contents of proximate compositions, free fatty acids, tetramethylpyrazine (6.91 mg/g DW), coixol (0.62 mg/g DW), coixenolide (4.21% DW), coixan (35.10% DW), and triterpenoids (17.41 mg/g DW). The higher contents of total phenolics and flavonoids, stronger antioxidant activity, and higher color differences were observed in HAD and IRD samples. MVD displayed the shorter drying time, higher γ-aminobutyric acid content, and higher retention ratios of tetramethylpyrazine (75.54%), coixol (87.10%), coixenolide (98.57%), and coixan (99.11%). Pearson's correlation coefficient exhibited that the positive correlation between the contents of phenolics and flavonoids and the antioxidant activities of all dried BPA samples was observed (R 2 > 0.881, p < .05). Principal component analysis showed that the top three categories of comprehensive quality were FVD-, MVD-, and VD-treated BPA samples. In conclusion, MVD should be a potential preservation method to obtain high-quality dried BPA for short drying time and high comprehensive quality.

Determination of Various Drying Methods' Impact on Odour Quality of True Lavender (Lavandula angustifolia Mill.) Flowers

True lavender flowers (Lavandula angustifolia Mill.) is a critical source of essential oils and a flavouring agent used in numerous industries like foods, cosmetics and pharmaceuticals. Its main volatile constituents are linalool and linalyl acetate, which are commonly considered as main odour-active constituents (OACs). Nevertheless, the quality of true lavender flowers is highly dependent on its post-harvest treatment, mainly the preservation method. Recognising that drying is the most frequently used preservation method, the influence of various drying methods, including convective drying (CD) at 50, 60 and 70 °C, vacuum-microwave drying (VMD) with powers 240, 360 and 480 W and combined convective pre-drying at 60 °C followed by vacuum-microwave finish-drying with power 480 W (CPD-VMFD), on the quality of true lavender flowers was verified. The evaluation of influence was carried out by HS-SPME(HS, solid-phase microextraction), GC-MS, GC-MS-O (gas chromatography–mass spectrometry–olfactometry) techniques. Moreover, the sensory panel has assessed the sample odour quality. As a result, the optimal drying methods regarding the requirements for products were established. Overall, for total essential oil recovery, CD at 50 °C is the optimal drying method, while for odour quality concerning the sensory panel evaluation, VMD with power 360 W combined CPD-VMFD and CD at 50 °C is the optimal drying method.

[Effects of three drying methods on the physical properties and drug delivery in chitosan microspheres]

OBJECTIVE

The purpose of this study is to investigate the effects of different drying methods on the physical properties and drug delivery of chitosan microspheres.

METHODS

Three types of drying methods were utilized, including air drying and freeze drying after freezing at -20 ℃ (slow cooling) and at -80 ℃ (fast cooling). The physical properties of microspheres were characterized. Utilizing bovine serum albumin (BSA) as the model drug, the in-vitro release behaviors of drug-loaded beads were investigated.

RESULTS

By comparing the physical properties of the different drying methods, the microspheres' diameters, porosities, and surface area were observed to increase successively from air drying and slow cooling to fast cooling, whereas the pore size and the swelling and degradation rates varied. The drug-loading experiments revealed that the loading capacity of air-dried microspheres was the lowest and the release rate was the slowest. Although the loading capacity of fast cooling microspheres was high, an obvious burst release was observed. The loading capacity of slow cooling microspheres was similar to that of the fast cooling microspheres and the loaded BSA can be released continuously.

CONCLUSIONS

The results indicate that different drying methods can affect the physical properties of chitosan microspheres, which further influence drug loading and release.

Evaluation of the impact of different drying methods on the phenolic compounds, antioxidant activity, and in vitro digestion of green coffee beans

We investigated the effects of different drying methods (room temperature drying, heat pump drying, freeze drying, microwave vacuum drying [MVD], and combined microwave power vacuum drying) on the active ingredients of green coffee beans. We specifically focused on eleven phenolic acids, total phenolic content (TPC), total flavonoid content, antioxidant activity, polyphenol oxidase (PPO), the inhibition of linoleic acid peroxidation (LPO), and enzyme activity, and the bio-accessibility in vitro and bioavailability of phenolics and antioxidant activities were also evaluated. MVD-treated beans had the lowest PPO activity and the highest contents of 5-caffeoylquinic acid (1.39 g/100 g DW), 3-feruloylquinic acid (0.25 g/100 g DW), 4-feruloylquinic acid (0.25 g/100 g DW), 5-feruloylquinic acid (1.52 g/100 g DW), and TPC (5.98 g GAE/100 g DW), and the highest antioxidant activity. MVD was the least time-consuming (0.63 hr/kg) and energy-consuming (1.88 kwh/kg) method. Moreover, the strongest inhibition of LPO and α-glucosidase was observed in MVD-treated beans. Thus, MVD is suggested to be the most suitable drying technique for the preservation of phenolic compounds and bioactivities of green coffee beans.

Effect of Drying Methods on the Microstructure, Bioactivity Substances, and Antityrosinase Activity of Asparagus Stems

The impacts of vacuum drying (VD), far-infrared drying (FIRD), hot air drying (HAD), and freeze drying (FD), as representative food drying methods, on structural characterization, bioactive substances, and antityrosinase activity of Asparagus have been assessed. The microstructure characterization by scanning electron microscopy indicated that VD treatment led to serious breaking of the vascular bundle and epithelial cells and provided higher free polyphenol (FP) and bound polyphenol (BP) contents. Besides, the smaller individual molecule (weight and hydroxy and phenolic rings) polyphenols bound to cellulose to a lesser extent than larger molecules, i.e., rutin and quercetin. In contrast, FD extracts possessed lower polyphenol contents but higher saponin and chlorophyll contents. The antityrosinase activity inhibition rates of FD and VD extracts were higher than those of FIRD and HAD for both mono- and diphenolase. The FP extract of VD, which possessed more polyphenolic compounds, had greater antityrosinase activity than BP.

[The influence of the drying method for food properties and hypolidemic potential of oyster mushrooms (Pleurotus ostreatus)]

The aim of this research was to study the influence of two drying methods: freeze-drying sublimation and dry-air drying on the selected nutritional properties and hypolipidemic potential of fruiting bodies of oyster mushroom (Pleurotus ostreatus). The criteria for evaluation of the food properties were the color, the morphological structure, regidratation capacity, the total level of soluble proteins, fats, polysaccharides, free amino acids and monosaccharides. Lipid-lowering potential of oyster mushroom was evaluated by the concentration of lovastatin and the level of antioxidant activity. It has been experimentally revealed that the value of optical density of hydro-alcohol extracts of dried oyster mushrooms at a wavelength of 295 nm most clearly characterized its color which intensity was almost twice less in sublimated mushrooms, than шт the sample dried by dry-air method. Histological data showed that dry-air drying lead to the destruction of the mushroom cells and to the formation of a dense layered structure. Sublimation drying preserved the ordered cell structure and provided less deformation and shrinkage of the tissues. Using X-ray microtomography it was reported that freeze-dried mushrooms had uniform pore volume distribution. Dry-air dehydration method lead to the formation of larger cavities. The average percentage of the open pores was: 29.41±0.52% (after dry-air method), 11.10±0.41% (after freeze-drying method). Respectively the number of closed pores, which reflected the true value of porosity, was 0.99±0.01 and 1.75±0.01%. Structural differences of the samples of the dry oyster mushroom combined with their unequal hydration ability. Indicator of rehydration for oyster mushroom dried by sublimation method was 5.4±0.1, and for samples obtained by dry-air method it was 3.2±0.1. Respectively the average time of maximum water absorption was 22.7±1.8 and 45.3±2.9 minutes. It was found that the freeze-drying sublimation conditions were more conducive for the preservation of the biologically active protein and polysaccharide components of oyster mushrooms and on the other hand dry-air drying method increased the nutritional value of oyster mushrooms due to the reactions of polysaccharides autohydrolysis. The number of proteins and polysaccharides of the Oyster mushrooms samples dried by dry-air method and freeze-drying method was 72.0% and 56.0% respectively. Concentrations of free amino acids and glucose in the samples dried by freeze-drying and dry-air methods were 11.60±0.31%; 175.20±6.10 mg% and 7.00±0.28%; 144.0±5.7 mg% respectively. It has been experimentally recorded that the conditions of freeze drying were optimal in terms of ensuring the preservation of the content of natural statin and the antioxidant capacity of oyster mushrooms that provided its hypolipidemic potential. The amount of lovastatin in an the freeze-dried samples was 342±9.0 mg/kg, and was significantly higher than in the samples received by dry-air method - 190±6.0 mg/kg. The level of antioxidant activity of the oyster mushrooms samples were respectively 3.83±0.02 against 2.0±0.03 mmol/100 g. The conducted researches proved that for the production of dry oyster mushroom as a potential biologically active feedstock for the functional food products with lipid-regulating directivity the choice of the drying method had a fundamental importance.

[Effects of different drying methods on content of bioactive component and antioxidant activity in Lycium ruthenicum]

To compare the appearances, tastes, contents of bioactive components and antioxidant activity of Lyceum ruthenicum under different drying methods, so as to direct its production practice. The folin-phenol colorimetric method, UV, extinction coefficient method and DPPH, as well as fluorescence recovery after photobleaching (FRAP) method to determine the contents of polyphenols, proanthocyanidins, total anthocyanin and antioxidant activity under different drying methods： vacuum freeze drying, low-temperature oven drying and air drying for L. ruthenicum. The results showed that the drying methods had certain effects on its appearances, tastes, contents of bioactive components and antioxidant activity. The appearances and tastes were best after the L. ruthenicum was dried by vacuum freeze drying, with significantly lower moisture than air drying method. The contents of total polyphenols, anthocyanin and proanthocyanidins were highest by air-drying but lowest by low temperature oven drying in L. ruthenicum. The scavenging ability to DPPH was strongest by freeze-drying and lowest by low temperature oven drying, while the antioxidant activity was strongest by air-drying in the FRAT method. In addition, the appearances and tastes were poor in air drying, with higher moisture but highest contents of the three bioactive components. Therefore, the drying methods for L. ruthenicum shall be comprehensively considered.

Identification of the compositional changes in Orthosiphon stamineus leaves triggered by different drying techniques using 1 H NMR metabolomics

BACKGROUND

Java tea is a well-known herbal infusion prepared from the leaves of Orthosiphon stamineus (OS). The biological properties of tea are in direct correlation with the primary and secondary metabolite composition, which in turn largely depends on the choice of drying method. Herein, the impact of three commonly used drying methods, i.e. shade, microwave and freeze drying, on the metabolite composition and antioxidant activity of OS leaves was investigated using proton nuclear magnetic resonance (¹ H NMR) spectroscopy combined with multivariate classification and regression analysis tools.

RESULTS

A total of 31 constituents comprising primary and secondary metabolites belonging to the chemical classes of fatty acids, amino acids, sugars, terpenoids and phenolic compounds were identified. Shade-dried leaves were identified to possess the highest concentrations of bioactive secondary metabolites such as chlorogenic acid, caffeic acid, luteolin, orthosiphol and apigenin, followed by microwave-dried samples. Freeze-dried leaves had higher concentrations of choline, amino acids leucine, alanine and glutamine and sugars such as fructose and α-glucose, but contained the lowest levels of secondary metabolites.

CONCLUSION

Metabolite profiling coupled with multivariate analysis identified shade drying as the best method to prepare OS leaves as Java tea or to include in traditional medicine preparation. © 2017 Society of Chemical Industry.

Comparative Evaluation of Physicochemical Properties of Pine Needle Powders Prepared by Different Drying Methods

Systematic study of how different drying methods, namely hot-air drying, vacuum-drying, and freeze-drying, affect color, browning index, degree of rehydration, water solubility, and vitamin C content is critical for utilizing pine needle powders (PNP) as a novel ingredient in functional foods. Samples prepared by vacuum-drying showed a significantly higher L*-value, whereas higher a*- and b*-values were detected in the hot-air dried samples (P<0.05). The browning index was significantly higher in samples prepared by vacuum-drying compared to samples prepared by freeze-drying (P<0.05). Freeze-dried PNP exhibited a significantly higher degree of rehydration than hot-air dried samples (P<0.05). Water solubilities of freeze-dried and hot-air dried samples were significantly higher than that of vacuum-dried sample (P<0.05). Vitamin C was less destroyed during freeze-drying compared to hot-air or vacuum-drying (P<0.05). Freeze-dried samples displayed a clear porous structure and appeared to have a bigger space, whereas hot-air dried samples showed lower porosity than vacuum and freeze-dried samples.

Effect of different drying methods on chlorophyll, ascorbic acid and antioxidant compounds retention of leaves of Hibiscus sabdariffa L

BACKGROUND

Use of the indigenous, easily accessible leafy vegetable roselle (Hibiscus sabdariffa L.) for value addition is gaining impetus as its nutritive and nutraceutical compounds are exposed by investigations. Being a perishable, storage is challenging, hence different methods of drying have been an attractive alternative for its postharvest usage in foods without much compromising its quality and antioxidant potential.

RESULTS

Room- and freeze-dried samples were found to have best quality in terms of colour, total flavonoid content (18.53 ± 2.39 and 18.66 ± 1.06 g kg(-1) respectively), total phenolic content (17.76 ± 1.93 and 18.91 ± 0.48 g kg(-1)), chlorophyll content (1.59 ± 0.001 and 1.55 ± 0.001 g kg(-1)) and ascorbic acid content (11.11 ± 1.04 and 8.92 ± 0.94 g kg(-1)) compared with those subjected to infrared, crossflow, microwave, oven or sun drying. Samples treated by room and freeze drying retained maximum antioxidant potential as shown by the phosphomolybdate method and the 2,2-diphenyl-1-picrylhydrazyl free radical-scavenging activity and ferric-reducing antioxidant power assays. Cold water and hot water extracts showed significantly higher total phenolic content and total antioxidant activity owing to the greater solubility of phenolics and destruction of cellular components in polar solvents than in organic solvents.

CONCLUSION

The data obtained show the potential for retaining quality parameters of roselle leaf under suitable drying methods.

Comparative studies on chemical parameters and antioxidant properties of stipes and caps of shiitake mushroom as affected by different drying methods

BACKGROUND

Shiitake, the second most cultivated mushroom, is famous for its high nutritional value and medicinal properties. In this study, various chemical parameters and antioxidant properties of caps and stipes of shiitake mushroom dried by different methods (freeze-drying, shade drying and hot air drying) were comparatively investigated by spectrophotometric assays, high-performance liquid chromatography, 1,1'-diphenyl-2-picrylhydrazyl assay, ferric reducing power assay and lipid peroxidation inhibition assay.

RESULTS

The contents of amino acids, neutral sugar and total phenolics in stipes were higher than those in caps of shiitake, while caps showed advantages in terms of their contents of protein and eritadenine. The chemical parameters and antioxidant activities of shiitake were significantly affected by the drying method used.

CONCLUSION

The contents of total phenolics, amino acids and neutral sugar in stipes were higher than those in caps of shiitake, which suggested that stipes were more nutritional than caps in some respects. Hot air drying at 50 °C resulted in high total phenolic, amino acid, uronic acid and neutral sugar contents and antioxidant activities, which could be useful for the application of shiitake and related products in the food industry.