Effect of Convective and Vacuum–Microwave Drying on the Bioactive Compounds, Color, and Antioxidant Capacity of Sour Cherries

Optimization of Processing Parameters for Continuous Microwave Drying of Crab Apple Slices via Response Surface Methodology

To improve product quality and obtain suitable processing parameters for crab apple slices (CASs) produced by continuous microwave drying (CMD), the effects of processing parameters, including slice thickness, microwave power, air velocity, and conveyor belt speed, on the evaluation indexes in terms of temperature, moisture content, color (L*, a*, b*), hardness, brittleness, and total phenolic content of CASs were investigated via the response surface method. The results indicated that microwave power has the greatest effect on the evaluation indexes applied to the CASs under CMD, followed by air velocity, slice thickness, and conveyor belt speed. To produce the desired product quality, the appropriate parameters for CMD of CASs were optimized as 1.25 mm slice thickness, 14,630 W microwave power, 0.50 m·s-1 air velocity, and 0.33 m·min-1 conveyor belt speed. Following that, the moisture content under CMD was found to be 13.53%, the desired color, hardness 0.79 g, brittleness 12.97 (number of peaks), and the total phenolic content 5.48 mg·g-1. This research provides a theoretical framework for optimizing the processing parameters of CASs using the response surface method.

Encapsulated pomegranate peel extract as a potential antimicrobial ingredient from food waste

BACKGROUND

Pomegranate peel waste is a valuable reservoir of heat-sensitive total hydrolysable tannins (THT), with potential applications in food and pharmaceuticals. Preserving THT is challenging due to degradation post-extraction. We explore ionic gelation as an encapsulation method to optimize THT utilization.

RESULTS

Through external gelation, we optimized the process variables using Box-Behnken design. At 40 g kg-1 sodium alginate, 25 g kg-1 calcium chloride, and 300 g kg-1 pomegranate peel extract (PPE), we achieved an 83.65% encapsulation efficiency. Compared to spray drying, external gelation demonstrated superior performance, with enhanced release percentages and stability. Physical, phytochemical, and release profiles of encapsulates were extensively analysed. External gelation achieved an 87.5% release in 30 min, outperforming spray-dried counterparts (69.7% in 25 min). Encapsulated PPE exhibited robust antibacterial activity against Staphylococcus aureus (ATCC 25923) in powdered infant formula, with a 32 ± 0.01 mm zone of inhibition and 300 μg mL-1 minimum inhibitory concentration. Insights into S. aureus growth curves underlined the mechanism of action via membrane potential alterations. The results of carried investigations also showed that the antibacterial activity of the encapsulated PPE extracts against the targeted organism was identical to the antibacterial activity exhibited by synthetic antibiotics used generally to kill microorganisms in food. Therefore, from the findings, it can be concluded that the PPE encapsulate produced using the external gelation technique at the optimized condition displayed superior storage stability possessing strong antimicrobial activity when compared to encapsulate produced using the spray drying technique.

CONCLUSIONS

External gelation emerges as a potent technique for developing effective encapsulates enriched with natural antimicrobials or antibiotics. This approach holds promise for applications in food, pharmaceuticals, and nutraceuticals, enhancing stability and efficacy while reducing reliance on synthetic antibiotics. © 2024 Society of Chemical Industry.

Effects of Different Varieties on Physicochemical Properties, Browning Characteristics, and Quality Attributes of Mume fructus (Wumei)

The dried Mume fructus (MF) is a special food and herbal medicine with a long history of processing and application. The browning index (BI) of Prunus mume (PM) is pivotal in determining the medicinal value and edible quality of MF. Exploring the BI of PM holds significant importance for both the selection of PM varieties and understanding the formation mechanism of high-quality MF. This study systematically analyzed the physicochemical properties, BI, and quality indicators of four PM varieties (Qingzhu Mei, Yesheng Mei, Nangao Mei, and Zhaoshui Mei) after processing into MF. The results showed significant differences in eight physicochemical indicators among the four PM varieties (p < 0.05). Notably, Qingzhu Mei exhibited the highest titratable acid content, Nangao Mei had the most prominent soluble solid and soluble sugar content, and Zhaoshui Mei showed outstanding performance in reducing sugar, soluble protein, and free amino acids. Regarding drying characteristics, Yesheng Mei and Nangao Mei required a shorter drying time. In terms of BI, Nangao Mei exhibited the greatest degree of browning and its color appearance was darker. When considering quality evaluation, Nangao Mei excelled in rehydration ability and extract content, while Zhaoshui Mei demonstrated outstanding levels of total phenols, total flavonoids, and total antioxidant capacity. Overall, the evaluation suggested that the Nangao Mei variety was more suitable for MF processing. These research results provide a valuable theoretical foundation for understanding the BI of PM varieties and serve as a reference for the selection of PM varieties as raw materials for processing MF.

Antioxidant compounds and activities of Perilla frutescens var. crispa and its processed products

Perilla frutescens var. crispa 'Antisperill' has stronger anti-inflammatory effects than the original cultivar (red perilla), but studies on its bioactive compounds are limited. This study aimed to evaluate the antioxidant compounds and activity of red perilla and 'Antisperill', as well as their processed products using freeze drying (FD) and microwave-assisted low temperature vacuum drying (MVD). Red perilla had higher antioxidant compounds and activities than 'Antisperill'. MVD showed significantly greater antioxidant properties than FD among the processed products. Isoegomaketone, studied for its anti-obesity, antioxidant, anti-inflammatory, and anticancer properties, was only found in 'Antisperill' and its processed products, with the highest content in 'Antisperill' MVD samples. This study highlights that 'Antisperill' contains various antioxidants, and MVD is the optimal drying method to preserve and enhance its antioxidant content. As a result, 'Antisperill' could potentially serve as a natural antioxidant with both anti-inflammatory and antioxidant functions.

Quality Evaluation and Browning Control in the Multi-Stage Processing of Mume Fructus (Wumei)

The dried Mume Fructus (MF), called Wumei in China, is a unique food with medicinal and edible effects. But its actual production method is outdated with low efficiency and inconsistent quality. This study systematically investigated the influence of moisture content (MC), temperature, and relative humidity (RH) on the browning reaction and quality characteristics of the MF and proposed a continuous processing strategy of the three-stage variable process for MF production based on the precise process control of the temperature and the RH. The production process of MF was divided into three stages: preliminary dehydration, browning, and drying. The results showed that the browning reaction rate and drying efficiency were optimal when the MC of the raw materials was reduced to 50%. In the browning stage, the degree of browning was better, and the antioxidant capacity reached the maximum of 64.38 mg/g DM under a processing temperature of 80 °C and an RH of more than 60%. As the RH increased, the drying rate decreased, and the ash content exhibited an increase. Therefore, the optimal processing parameters for the browning stage were determined to be a temperature of 80 °C and an RH of 60%. In the final drying stage, a temperature of 60 °C coupled with a dehumidification mode proved sufficient to ensure efficient drying without compromising the quality of the MF. This study revealed the reaction mechanism of the rapid browning processing of MF, which has important guiding significance for the rapid processing of browning foods.

Rosmarinic Acid and Flavonoids of the Seagrass Zostera noltei: New Aspects on Their Quantification and Their Correlation with Sunlight Exposure

Seagrasses are plants adapted to the marine environment that inhabit shallow coastal waters, where they may be exposed to direct sunlight during low tides. These plants have photoprotection mechanisms, which could include the use of phenolic secondary metabolites. In this study, rosmarinic acid (RA) and the flavonoids of Zostera noltei from the Bay of Cadiz (Spain) have been analyzed, first to define suitable conditions of leaves (i.e., fresh, dried, or frozen) for quantitative analysis, and then to explore the potential correlation between the phenolic profile of the leaves and sunlight exposure using an in situ experimental approach. Compared with fresh leaves, the contents of RA and flavonoids were significantly lower in air-dried and freeze-dried leaves. Freezing caused highly variable effects on RA and did not affect to flavonoid levels. On the other hand, the content of RA was significantly higher in plants that emerged during low tides than in plants permanently submerged, while plants underneath an artificial UV filter experienced a progressive reduction in RA content. However, the major flavonoids did not show a clear response to sunlight exposure and were unresponsive to diminished UV incidence. The results showed a positive correlation of RA with direct sunlight and UV exposure of leaves, suggesting that this compound contributes to the photoprotection of Z. noltei.

Effects of gum-based coatings combined with ultrasonic pretreatment before drying on quality of sour cherries

Application of pretreatment methods such as ultrasound and edible coatings is used to reduce processing time and/or preserve food product quality in drying technology. The aim of this research was to measure the impacts of gum-based coatings (guar, sodium alginate, and basil seed gums) in combination with sonication before drying on total phenolic content (TPC), antioxidant capacity (AC), effective water diffusivity (Deff), total color difference (ΔE), surface shrinkage (SS), and rehydration ratio (RR) of sour cherries. Ultrasonic pretreatment (40 kHz, 150 W, at 25 °C, for 12 min) increased the TPC, AC, Deff, and RR, and decreased the drying time, ΔE, and SS values of sour cherries. Edible coating increased the TPC, AC, drying time, and RR, and decreased the Deff, ΔE, and SS values of sonicated sour cherries. The TPC for untreated, uncoated-sonicated, guar gum-coated, sodium alginate-coated, and basil seed gum-coated sour cherries were 2965.9, 3398.1, 3480.8, 3511.0, and 3898.3 Âµg gallic acid equivalent/g dry, respectively. The highest value of AC (71.2±3.7 %) was observed on coated sour cherries by basil seed gum. The experimental data for drying curves were fitted to several widely used models, and the Midilli model using the experimental constants that best represent the drying rate of sour cherries. The edible coatings significantly reduced the color changes and shrinkage of dried sour cherries, with the lowest ΔE and SS values in the basil seed gum-coated samples (p < 0.05).

The impact of different drying methods on the physical properties, bioactive components, antioxidant capacity, volatile components and industrial application of coffee peel

This study evaluated the effects of hot air drying (HAD), microwave drying (MD), vacuum drying (VD), sun drying (SD) and vacuum freeze drying (VFD) on the physical properties, bioactive components, antioxidant capacity, volatile components and industrial application of coffee peel. The results showed VFD could retain the appearance color, total phenolics (19.49 mg GAE/g DW), total flavonoids (9.65 mg CE/g DW), caffeine (3.15 mg/g DW), trigonelline (2.71 mg/g DW), and antioxidant capacities of fresh sample to the greatest extent, but its operating cost was significantly higher than other treatments and total volatile components were in the minimum levels. HAD and SD exhibited the highest loss rates of total phenols and antioxidant capacities, exceeding 50%. MD offered the lowest operating cost, superior retention of bioactive components, and the richest variety and quantity of volatile compounds. Therefore, it is recommended to use MD to dehydrate the coffee peel in actual production.

Investigation into Polyphenol Profile and Biological Activities of Enriched Persimmon/Apple Smoothies during Storage

Smoothies are becoming an increasingly popular product as a healthy alternative to snacks. The consumer expects from this product that, apart from its nutritional value, it will also be qualitatively stable during storage. Therefore, in this study, original smoothies obtained with persimmon fruit puree and apple juice (Dk/Md) enriched with Arbutus unedo fruits, Myrtus communis purple berry extract, Acca sellowiana, and Crocus sativus petal juice were evaluated for their polyphenol composition, antioxidant activity, and inhibition on targeted digestive enzymes, over six months of storage. The amount of polyphenols evaluated by UPLC-PDA analysis decreased in six months from 23.5% for both Dk/Md and enriched C. sativus smoothies to 42.5% for enriched A. sellowiana, with anthocyanins the most sensitive compounds (71.7-100% loss). Values of antioxidant assays generally strongly decreased during the first three months (up to ca. 60%) and to a lesser extent in the following three months (0.4-27%). In addition, inhibitory activity on α-amylase, α-glucosidase, and pancreatic lipase, especially on the last two enzymes, was negatively affected by time storage. The outcome of this study indicates that persimmon fruit is a good option for producing smoothies, and enrichment with other plant extracts can enhance the bioactive compound content and biological activities. It is recommended that appropriate storage strategies to preserve the properties of those smoothies should be developed.

Prototype of an Innovative Vacuum Dryer with an Ejector System: Comparative Drying Analysis with a Vacuum Dryer with a Vacuum Pump on Selected Fruits

The following article describes new research about the design, construction and installation of the new prototype of a vacuum dryer with an ejector system. Moreover, the testing of this new prototype involved comparing the qualities of fruit dried in a vacuum drier with an ejector system to fruit dried in a convectional vacuum drier. The data obtained were then analyzed and presented. Due to their economic relevance and highly valuable nutritional value and sensory properties, sour cherries and apricots have been chosen to be the subjects for the testing. The most appropriate quality indicators for analyzing were moisture content, aw value, share and penetration force, total phenol, flavonoid and anthocyanin content and antioxidant activity (FRAP, DPPH and ABTS test). The main results of this study were achieved by designing, constructing, installing and testing the usage of the innovative prototype of a vacuum dryer with an ejector system in the laboratory of the Technology of fruit and vegetable products of the Faculty of Technology Novi Sad, University of Novi Sad. Based on our analyses of the obtained data, it was concluded that vacuum dryer with an ejector system are similar to vacuum dryer with a vacuum pump in terms of all tested physical, chemical and biological properties of dried samples. We observed similarities in some of the most important parameters, including product safety and quality, such as the aw value and the total phenol content, respectively. For example, in dried sour cherry, the aw values ranged from 0.250 to 0.521 with the vacuum pump and from 0.232 to 0.417 with the ejector system; the total phenol content ranged from 2322 to 2765 mg GAE/100 g DW with the vacuum pump and from 2327 to 2617 mg GAE/100 g DW with the ejector system. In dried apricot, the aw ranged from 0.176 to 0.405 with the vacuum pump and from 0.166 to 0.313 with the ejector system; total phenol content ranged from 392 to 439 mg GAE/100 g DW with the vacuum pump and from 378 to 428 mg GAE/100 g DW with the ejector system.

Impact of Processing and Physicochemical Parameter on Hibiscus sabdariffa Calyxes Biomolecules and Antioxidant Activity: From Powder Production to Reconstitution

Hibiscus sabdariffa is a tropical plant with red calyxes whose anthocyanins, phenols, and antioxidant activity make it attractive to consumers both from a nutritional and medicinal standpoint. Its seasonality, perishability, and anthocyanin instability, led to the setup of stabilization methods comprising drying and powdering. However, its properties can often be altered during these stabilization processes. Treatments such as dehumidified-air-drying, infrared drying, and oven-drying, and their combination showed better quality preservation. Moreover, powder production enables superior biomolecule extractability which can be linked to a higher bioaccessibility. However, the required temperatures for powder production increase the bioactive molecules degradation leading to their antioxidant activity loss. To overcome this issue, ambient or cryogenic grinding could be an excellent method to improve the biomolecule bioavailability and accessibility if the processing steps are well mastered. To be sure to benefit from the final nutritional quality of the powder, such as the antioxidant activity of biomolecules, powders have to offer excellent reconstitutability which is linked to powder physicochemical properties and the reconstitution media. Typically, the finest powder granulometry and using an agitated low-temperature reconstitution media allow for improving anthocyanin extractability and stability. In this review, the relevant physicochemical and processing parameters influencing plant powder features from processing transformation to reconstitution will be presented with a focus on bioactive molecules and antioxidant activity preservation.

Nanofood Process Technology: Insights on How Sustainability Informs Process Design

Nanostructured products are an actively growing area for food research, but there is little information on the sustainability of processes used to make these products. In this Review, we advocate for selection of sustainable process technologies during initial stages of laboratory-scale developments of nanofoods. We show that selection is assisted by predictive sustainability assessment(s) based on conventional technologies, including exploratory ex ante and "anticipatory" life-cycle assessment. We demonstrate that sustainability assessments for conventional food process technologies can be leveraged to design nanofood process concepts and technologies. We critically review emerging nanostructured food products including encapsulated bioactive molecules and processes used to structure these foods at laboratory, pilot, and industrial scales. We apply a rational method via learning lessons from sustainability of unit operations in conventional food processing and critically apportioned lessons between emerging and conventional approaches. We conclude that this method provides a quantitative means to incorporate sustainability during process design for nanostructured foods. Findings will be of interest and benefit to a range of food researchers, engineers, and manufacturers of process equipment.

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.

Elucidation of flavanones, phenols and antioxidant capacity influenced by drying methods from physiologically dropped underutilized Citrus grandis fruits

Introduction

Nutritional content in citrus fruit is enormous. Citrus grandis (L.) Osbeck is underutilised citrus crop that receives little attention due to the lack of knowledge regarding its nutritional value. Citrus waste disposal poses a problem due to economic and environmental factors.

Methods

The metabolites flavonoids, phenols and antioxidant capacity in the dropped fruits of the underutilised citrus species pomelo (Citrus grandis (L.) Osbeck) were examined.

Results and discussion

Hesperidin varied from 1.22 to 2.83% and 1.08 to 1.16% from 10 mm to 14 mm whereas naringin dominates in fruits measuring 10 mm and 12mm with 60.61%, 60.77%, and 47.76%, 45.87% in freeze dried (FD) and hot air oven dried (HAOD) samples. According to the results of the antioxidant assays, the highest concentrations of ABTS azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) and DPPH (2, 2-diphenyl-1-picrylhydrazyl radical) were found in freeze dried samples, ranging from 9.679 to 10.416 mmol L^-1 Trolox and 14.825 to 16.432 mmol L^-1 Trolox, respectively. However, the Ferric Reducing Antioxidant Power (FRAP) assay revealed higher content in samples of both FD and HAOD that were 10mm in size (4.578 mmol L^-1 Trolox and 3.730 mmol L^-1 Trolox). Total phenol content was measured, and the highest concentrations were found in fruits with a diameter between 10 mm and 18 mm. It ranged from 48.479 to 54.498 mg GAE L^-1 in FD samples and from 45.757 to 51.159 mg GAE L^-1 in HAOD samples. The smallest fruits, or those that were still in the immature stage, had the highest content. It was found that when the immature dropped fruits were dried by HAOD, the content decreased. At p<0.01 and p<0.05, there was a significant positive correlation between the flavonoids, antioxidants, and total phenols. The results showed that the immature dropped immature fruits of lesser known underutilised citrus sp. Citrus grandis can act as potential source of flavonoids, total phenol concentration, and antioxidant potential. Freeze drying can be recommended to recover the most bioactive substances from physiologically dropped fruits of Citrus grandis for use in the pharmaceutical and nutraceutical sectors. This study will help in reducing the environmental impact caused due to citrus dropped fruits and its responsible management.

Physical character, total polyphenols, anthocyanin profile and antioxidant activity of red cabbage as affected by five processing methods

Understanding the influence of processing methods on the phytochemicals of fruits and vegetables is of importance in retaining the health-benefiting properties of those products. The aim of this study was to investigate the effects of five processing methods including freeze drying (FD), hot air drying (HD), water boiling (WB), steaming (ST), and pickling (PI) on the physical character, total polyphenols, anthocyanin profile and antioxidant activity of red cabbage. Different color and texture were observed after different processing methods. Total anthocyanin content was reduced by 73%, 72%, 41%, 16%, and 30% in FD, HD, WB, ST and PI processed red cabbage, respectively. PI samples showed the highest values of total polyphenols and DPPH scavenge activity among all the processed red cabbage. Both FD and HD samples had relatively low values of total polyphenols and DPPH scavenge activity. However, FD sample had the highest FRAP values. UPLC-QqQ-MS/MS analysis showed that fresh red cabbage contained 22 anthocyanins among which cyanidin-3-diglucoside-5-glucoside was the prominent. Compared with drying process, WB, ST and PI decreased the loss of most of the anthocyanin component in red cabbage. Correlation analysis indicated that antioxidant capacity as determined by DPPH of red cabbage was positively and significantly correlated with the total anthocyanins. This study suggested that drying induced significant loss of phytochemicals in red cabbage, and WB, ST, as well as PI were advisable ways for daily consumption of red cabbage considering the bioactive components. Especially, ST was the best way to retain anthocyanins in red cabbage.

Antioxidant Activity and Inhibition of Digestive Enzymes of New Strawberry Tree Fruit/Apple Smoothies

In this study, original smoothies obtained with strawberry tree fruit puree and apple juice enriched with Diospyros kaki fruits, Myrtus communis purple berry extract, Acca sellowiana, and Crocus sativus petal juice were evaluated for their antioxidant activity and inhibition of targeted digestive enzymes. Values of CUPRAC, FRAP, ORAC, DPPH•, and ABTS•+ assays generally increased with plant enrichment, particularly for A. sellowiana addition (ABTS•+ 2.51 ± 0.01 mmol Trolox/100 g fw). The same trend was observed regarding the ability to scavenge reactive oxygen species (ROS) tested in Caco-2 cell cultures. Inhibitory activity on α-amylase and α-glucosidase was increased by D. kaki, M. communis, and A. sellowiana. Total polyphenols evaluated by UPLC-PDA analysis ranged between 535.75 ± 3.11 and 635.96 ± 5.21 mg/100 g fw, and A. sellowiana provided the higher amount. Flavan-3-ols accounted for more than 70% of phenolic compounds, and only smoothies enriched with C. sativus showed a high amount of anthocyanins (25.12 ± 0.18 mg/100 g fw). The outcome of this study indicates these original smoothies as a possible ally in counteracting oxidative stress, as established by their favourable antioxidant compound profile, thus suggesting an interesting future application as nutraceuticals.

Response Surface Methodology Approach for Predicting Convective/Infrared Drying, Quality, Bioactive and Vitamin C Characteristics of Pumpkin Slices

In this research, a convective/infrared (CV/IR) dryer was used to dry pumpkin slices. For optimization of the drying conditions, the influence of three levels of independent variables including air temperature (40, 55, and 70 °C), air velocity (0.5, 1, and 1.5 m/s), and IR power (250, 500, and 750 W) were assessed by response surface method (RSM) through a face-centered central composite design. Analysis of variance (non-fitting factor and R² value) was employed to determine the desirability of the model. Response surfaces and diagrams were also utilized to show the interactive influence of the independent variables with the response variables (drying time, energy consumption, shrinkage, total color variation, rehydration ratio, total phenol, antioxidant, and vitamin C contents). According to the results, optimal drying conditions involved a temperature of 70 °C, air velocity of 0.69 m/s, and IR power of 750 W. At the mentioned conditions, response variables of drying time, energy consumption, shrinkage, color, rehydration ratio, total phenol, antioxidant, and vitamin C contents were 72.53 min, 24.52 MJ/kg, 23%, 14.74, 4.97, 617.97 mg GA/100 g dw, 81.57%, and 4.02 mg/g dw, with a confidence level of 0.948, respectively.

Effects of ultrasound pretreatment assisted drying methods on drying characteristics, physical and bioactive properties of windfall apples

BACKGROUND

Drying is one of the most important post-harvest processes in order to ensure that the products harvested in certain periods are consumed throughout the year. In this study, Golden Delicious, Oregon Spur and Granny Smith apple cultivars (fallen apples) were dried in open-sun, a controlled glasshouse, microwave oven (200 W), hybrid system (100 W + 60 °C), convective greenhouse (70 °C) and freeze-dryer (-55 °C) with and without ultrasound pretreatments.

RESULTS

Present findings revealed that the longest drying duration was observed in freeze-drying and the shortest in microwave drying. The greatest color change (ΔE) was observed in ultrasound pretreated Oregon Spur apples dried in a controlled glasshouse. The greatest total phenolics (40.08 mg GAE g^-1 ), DPPH (2,2-diphenyl-1-picrylhydrazyl) inhibition activity (46.96%), FRAP (ferric reducing ability of plasma) antioxidant activity (68.01 μg Trolox g^-1 ) and ascorbic acid content (1.52 mg AAE g^-1 ) were observed in open sun-dried Granny Smith apples without ultrasound pretreatment.

CONCLUSIONS

Generally, microwave and hybrid drying yielded better outcomes for bioactive, HMF (5-hydroxymethyl-2-furfural) and drying characteristics of windfall apples. © 2022 Society of Chemical Industry.

The Effect of Nonthermal Pretreatment on the Drying Kinetics and Quality of Black Garlic

Black garlic is obtained from regular garlic (Allium sativum L.) through the aging process and consequently gains many health-promoting properties, including antidiabetic and antioxidant. However, the material is still prone to microbiological deterioration and requires a long time to dry due to its properties. Therefore, this study aimed to investigate the effect of various drying methods on the quality of black garlic as well as determine the influence of selected nonthermal pretreatments on the drying kinetics and quality of black garlic, which is especially important in the case of the materials that are difficult to dry. The Weibull model was chosen to describe drying kinetics. Additionally, color, water activity together with antioxidant activity, phenolic compounds, and antidiabetic potential were determined. This study found that the application of a pulsed electric field (PEF), a constant electric field (CEF) as well as a magnetic field (MF) significantly reduced the time of drying (by 32, 40, and 24 min for a PEF, a CEF, and a MF, respectively, compared to combined drying without the pretreatment), and resulted in high antidiabetic potential. However, the highest content of phenolic compounds (1123.54 and 1125.36 mg/100 g dm for VMD125 and CD3h-VMD, respectively) and antioxidant capacity (ABTS = 6.05 and 5.06 mmol Trolox/100 g dm for VMD500 and CD6h-VMD, respectively) were reported for black garlic treated by vacuum-microwave drying and combined convective pre-drying followed by vacuum-microwave drying. Overall, the nonthermal pretreatment decreased the time of drying and showed very good efficiency in maintaining the antidiabetic potential of black garlic, especially in the case of the materials pretreated by a constant electric field (IC₅₀ = 99 and 56 mg/mL, for α-amylase and α-glucosidase, respectively).

Microstructure Analysis and Quality Evaluation of Jujube Slices Dried by Hot Air Combined with Radio Frequency Heat Treatment at Different Drying Stages

Jujubes have been favored by consumers because of their rich nutrition and wide use. Hot air drying has been commercially and typically used to prolong shelf life and acquire the dried produce. Jujube slices were dried with hot air combined with radio frequency (RF) at different drying stages, namely, early (0–2 h, E-HA + RF), middle (2–4 h, M-HA + RF), later (4–6 h, L-HA + RF), and whole (0–6 h, W-HA + RF) stages. This study aimed to investigate the effects of different RF application stages on the microstructure, moisture absorption rate, color, and ascorbic acid of jujube slices. Compared with the hot air drying (HA) group, the E-HA + RF group obtained the best results among the experimental groups because it reduced the cells with a roundness of less than 0.4 by 5%. Moreover, the M-HA + RF group showed better results than those of other groups, with an 18.6% and 48.8% reduction in cells for a cross-sectional area less than 200 µm² and a perimeter less than 25 µm, respectively. The minimum total color difference (ΔE = 9.21 ± 0.31) and maximum retention of ascorbic acid (285.06 mg/100 g) were also observed in this group. Therefore, the method of hot air drying assisted by phased RF is viable in the drying industry to improve the quality of dried agricultural products and reduce energy consumption.

Neuroprotective Potential of Thinned Peaches Extracts Obtained by Pressurized Liquid Extraction after Different Drying Processes

Genetic, environmental and nutritional factors are suggested as primary factors of Alzheimer’s disease (AD), and secondary metabolites such as polyphenols present in thinned peaches are considered as good candidates for AD prevention. Thinned peaches are usually dried to avoid putrefaction, but the effects of the drying method and the extraction process on the polyphenol composition and the neuroprotective potential have never been addressed. In this work, a pressurized liquid extraction (PLE) method was optimized and applied to thinned peaches dried under different conditions, and their neuroprotective potential was evaluated in vitro. In addition, the PLE extracts were characterized via HPLC-Q-TOF-MS/MS, and a permeability assay was performed to evaluate the ability of the identified metabolites to cross the blood–brain barrier (BBB). The PLE extracts obtained from freeze-dried (FD) samples with 50% ethanol in water at 180 °C showed the best neuroprotective potential. Finally, among the 81 metabolites identified, isoferulic acid, 4-methyldaphnetin, coniferyl aldehyde and 3,4-dihydroxyacetophenone were found at higher concentrations in FD extracts. These metabolites are able to cross the BBB and are positively correlated with the neuroprotective potential, suggesting FD together with PLE extraction as the best combination to exploit the neuroprotective capacity of thinned peaches.

Analysis of Material-Characterization Properties of Post-Production Waste-The Case of Apple Pomace

The paper presents the material-characterization properties of apple pomace-the post-production waste of juice pressing. Tests were carried out on the basic physical properties of apple pomace: color, specific-density, and energy properties. Extensive material-composition analyses based on DSC (differential scanning calorimetry) and TGA (thermogravimetry) methods were also performed. It has been shown that pomace, due to its energy value, can be a good fuel. The obtained thermal data confirm the presence of cellulose, hemicelluloses, lignins and pectins in the analyzed pomace. The results confirm that dried apple pomace is microbiologically stable with good health-promoting properties.

Comparison of Different Drying Methods for Asparagus [Asparagus cochinchinensis (Lour.) Merr.] Root Volatile Compounds as Revealed Using Gas Chromatography Ion Mobility Spectrometry

Asparagus [Asparagus cochinchinensis (Lour.) Merr.] is a traditional herbal medicine plant commonly used to nourish yin, moisten dryness, and clear fire cough symptoms. Drying is an excellent option to conserve food materials, i.e., grains, fruits, vegetables, and herbs, reducing the raw materials volume and weight. This study aims to evaluate different drying approaches that could increase the value of asparagus, particularly as an ingredient in fast foods or as nutraceutical byproducts. The volatile components of asparagus roots were analyzed by using headspace-gas chromatography-ion mobility spectroscopy under different drying conditions, i.e., natural drying (ND) at ambient air temperature in the dark, well-ventilated room, temperature range 28-32°C, blast or oven drying at 50°C, heat pump or hot-air drying at temperature 50°C and air velocity at 1.5 ms-1 and vacuum freeze-drying at the temperature of -45°C and vacuum pressure of 10-30 Pa for 24 h. The findings revealed that the various drying processes had multiple effects on the color, odor index, and volatile compounds of the asparagus roots. As a result of the investigations, multiple characteristics of components, therefore, exploitation and comparison of various flavors; a total of 22 compounds were identified, such as alcohols, ketones, aldehydes, acids, esters, heterocyclic, and terpene. The present findings may help understand the flavor of the processed asparagus roots and find a better option for drying and processing.

Drying kinetics and physicochemical properties of kumquat under hot air and air-impingement jet dryings

Kumquat is famous for its unique flavor and nutritional value. In this study, the drying kinetics, moisture effective diffusivity, phytochemical properties, and antioxidant capacities of kumquat dried by hot air drying (HAD) and air-impingement jet drying (AIJD) were comparatively investigated. The results showed that drying rate, moisture effective diffusivity, and nutrient retention under AIJD were better than those under HAD. Fourteen polyphenols were identified by UPLC-QqQ-MS/MS in kumquat slices. The content of limonoid was significantly increased after AIJD. It was also found that high temperature contributed to a higher drying rate. However, most of the polyphenol components decreased at high drying temperatures. Accordingly, AIJD 60 °C was regarded as the optimum condition for kumquat drying. This work contributed to a better understanding of the drying character of kumquat under AIJD and showed the bioactive compounds and antioxidant activities are affected by drying methods.

Response Surface Approach to Optimize the Conditions of Foam Mat Drying of Plum in relation to the Physical-Chemical and Antioxidant Properties of Plum Powder

This research was done to optimize the influence of various egg albumin (EA) concentrations of 2, 4, and 6% as a foaming agent and whipping times of 5, 10, and 15 minutes, on physicochemical and antioxidant properties of plum powder produced using response surface methodology (RSM). Physical properties of the foam such as density, porosity, and expansion were determined. After drying and powder manufacturing, physical properties, namely, the water absorption index (WAI) and water solubility index (WSI), as well as chemical characteristics such as pH, titratable acidity, and browning index, were assessed. Finally, antioxidant capabilities such as the total phenol content (TPC), DPPH scavenging activity, beta carotene, and total flavonoid content (TFC) were measured. According to the findings, both whipping duration and EA concentration had a substantial effect on the foam forming characteristics. Foam expansion increased significantly with EA concentration and whipping time increase, but foam density exhibited an inverse relationship as expected. Increases in EA concentration and whipping duration both raised pH values whereas titratable acidity exhibited an inverse tendency as variable quantity rose. The browning index dropped as EA concentration increased. Antioxidant qualities were retained in dried sample powder as compared with the fresh sample, and they were also altered by variable changes. Overall, a 4% EA concentration for 10 to 15 minutes produced the best dehydration effects with the most antioxidant retention.

Edible coatings as osmotic dehydration pretreatment in nutrient-enhanced fruit or vegetable snacks development: A review

Edible coatings (ECs) are thin layers applied on food to protect it and improve quality. They are made from bio-based materials such as polysaccharides, proteins, lipids, or their composites. The incorporation of functional agents, such as bioactive compounds, vitamins, or antimicrobials into the EC, has been investigated to control the shelf life of many food products from horticulture ones to processed food. Osmotic dehydration (OD) as a mild technology may also positively impact the availability of innovative fruit snacks and consequently influence consumer health. Combination of the EC with the OD aims to remove water through the semipermeable membrane while limiting the transfer of solutes from the dehydrated tissue and in the opposite direction from the osmotic solution to the food. The development trend of the snack market is expanding, especially with health-promoting properties. Consumers pay increasing attention to quality of food and its beneficial effects on health. This review attempts to provide the advancement of recent studies on the application of the EC before the OD of different fresh or fresh-cut fruit and vegetables. A fundamental theory related to the methodology of creating the EC, their composition, and the influence on the physicochemical properties of products that are osmo-dehydrated to a medium water content or additionally dried to a low water content have been described. Efforts have been exerted to introduce hydrocolloids used in the production of the EC, including new sources of biopolymers such as agricultural waste and by-products. The perspectives of using ECs in the technology of producing pro-healthy snacks are emphasized.

The retention and bioavailability of phytochemicals in the manufacturing of baked snacks

There is a growing body of evidence supporting the role that phytochemicals play in reducing the risk of various chronic diseases. Although there has been a rise in health products marketed as being "supergrains," "superfood," or advertising their abundance in antioxidants, these food items are often limited to powdered blends, dried fruit, nuts, or seeds, rarely intercepting the market of baked snacks. This is in part due to the still limited understanding of the impact that different industrial processes have on phytochemicals in a complex food matrix and their corresponding bioavailability. This review brings together the current data on how various industrial dehydration processes influence the retention and bioaccessibility of phytochemicals in baked snacks. It considers the interplay of molecules in an intricate snack matrix, limitations of conventional technologies, and constraints with consumer acceptance preventing wider utilization of novel technologies. Furthermore, the review takes a holistic approach, encompassing each stage of production-discussing the potential for inclusion of by-products to promote a circular economy and the proposal for a shift in agriculture toward biofortification or tailored growing of crops for their nutritional and post-harvest attributes.

Reactivity of flavanols: Their fate in physical food processing and recent advances in their analysis by depolymerization

Flavanols, a subgroup of polyphenols, are secondary metabolites with antioxidant properties naturally produced in various plants (e.g., green tea, cocoa, grapes, and apples); they are a major polyphenol class in human foods and beverages, and have recognized effect on maintaining human health. Therefore, it is necessary to evaluate their changes (i.e., oxidation, polymerization, degradation, and epimerization) during various physical processing (i.e., heating, drying, mechanical shearing, high-pressure, ultrasound, and radiation) to improve the nutritional value of food products. However, the roles of flavanols, in particular for their polymerized forms, are often underestimated, for a large part because of analytical challenges: they are difficult to extract quantitatively, and their quantification demands chemical reactions. This review examines the existing data on the effects of different physical processing techniques on the content of flavanols and highlights the changes in epimerization and degree of polymerization, as well as some of the latest acidolysis methods for proanthocyanidin characterization and quantification. More and more evidence show that physical processing can affect content but also modify the structure of flavanols by promoting a series of internal reactions. The most important reactivity of flavanols in processing includes oxidative coupling and rearrangements, chain cleavage, structural rearrangements (e.g., polymerization, degradation, and epimerization), and addition to other macromolecules, that is, proteins and polysaccharides. Some acidolysis methods for the analysis of polymeric proanthocyanidins have been updated, which has contributed to complete analysis of proanthocyanidin structures in particular regarding their proportion of A-type proanthocyanidins and their degree of polymerization in various plants. However, future research is also needed to better extract and characterize high-polymer proanthocyanidins, whether in their native or modified forms.

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.

Effects of air-impingement jet drying on drying kinetics and quality retention of tomato slices

The purpose was to explore the drying kinetics, the moisture effective diffusivities, color, total polyphenols, lycopene and antioxidant activities of dried tomato slices by air-impingement jet drying (AIJD). The results showed that high temperature increased the drying rate, and Modified Page model accurately predicted the AIJD characteristics of tomato slices. AIJD is better than hot air drying in shortening drying time, enhancing drying rate and decreasing the loss of total polyphenols, lycopene and antioxidant capacity of tomato slices. Tomato slices dried by AIJD also showed higher lightness and redness. Lycopene content and antioxidant activity of tomato slices dried by AIJD were increased by higher drying temperature. Based on experimental data, AIJD at 80 °C can be used in tomato drying process due to the advantages in drying efficiency and content of bioactive compounds. This study will provide helpful information for the production of high quality of dried tomato products.

Chemical profile of Tetraclinis articulata (Vahl) Masters, and Juglans regia L. and Olea europaea L. var. Sylvestris used against oral diseases: in vitro analysis between polyphenolic content and aqueous extraction optimization

Objective

Optimization of aqueous extraction to extract the maximum amount of polyphenolic compounds that are used to treat oral disorders.

Methods

Using revelation tests for phytochemical screening, Folin-Ciocalteu reagent for total phenols, catechin standard for total flavonoids, acidified vanillin for total condensed tannins, and PCA analysis to detect different correlations between plants and between employed extractions.

Results

The highest (p < 0.0001); total flavonoides (195,80 ± 2,91 mg CE/g d.e) was obtained from decocted extract of Olea europaea L. subsp. europaea var. sylvestris, total phenolic (167,71 ± 12,52 mg GAE/g d.e) and total condensed tannins (250,44 ± 10,18 mg CE/g d.e) was obtained respectively from soxhlet extract and infused extract of Tetraclinis articulata L. whereas; The correlation analysis using Principal Component Analysis (PCA) was positive between infusion and decoction, between total flavonoids and total phenols which is not correlated with total condensed tannins.

Conclusion

Juglans regia L. bark contain a higher level of polyphenolic constituents than leaves, Decoction extraction of Olea europaea L. var. sylvestris leaf recommended to increase the yield of polychenolic extracts, condensed tannins of Tetraclinis articulata L. are degradable in high temperature.

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Walnut barks are richer in polyphenolic compounds than leaves.

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Barbary Thuya leaf is richer in degradable condensed tannins at high temperatures.

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Wild olive leaf is richer in flavonoids (195.80 mg EC/g of dry decocted extract).

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Condensed tannins are uncorrelated with phenols and flavonoids.

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Flavonoids are the major polyphenolic constituents.