Effect of Different Drying Methods on the Phytochemical and Antioxidant Properties of Soursop Leaves at Two Stages of Maturity

Soursop (Annona muricata L.) leaves are a rich source of bioactive compounds and antioxidant properties. However, they are non-economical and rapidly diminish due to insect damage and biochemical degradation. This study investigates the impact of different drying methods, including tray drying (TD), vacuum drying (VD), and freeze-drying (FD), on the phytochemical and antioxidant properties of soursop leaves at two maturity stages (young (YL) and mature (ML)). By analyzing their proximate composition, mineral content, color characteristics, pH, extraction yield, chlorophyll, ascorbic acid, total phenolics, flavonoids, and antioxidant activities, this study aims to optimize and select the appropriate drying techniques for soursop leaves. Results demonstrate that FD samples achieved the highest preservation of moisture-sensitive bioactive compounds and antioxidant properties followed by VD and TD. FD samples retained higher levels of chlorophyll (10.09-16.88 mg/g), ascorbic acid (15.91-19.89 mg/100g), phenolics (111.98-121.43 mg GAE/g), and flavonoids (68.91-72.45 mg QE/g) exhibited minimal browning and maintained stable pH (6.81-7.01) values. VD effectively reduced moisture content (3.03%) and preserved mineral concentrations, while TD led to significant nutrient loss despite its moisture removal efficiency. Additionally, ML consistently displayed higher nutrient and phytochemical concentrations than YL. This study highlights FD as the optimal method for preserving the health benefits of soursop leaves and suggests VD as a viable alternative when FD is not feasible. These findings are significant for developing cost-effective and efficient preservation strategies, enhancing the economic value of soursop leaves in various applications.

Effects of moisture content and packaging on color stability of red pepper (Capsicum annuum L.) powder

The color stability and quality changes of red pepper powder of various initial moisture content (7%, 10%, and 13%) and packaged with different materials, low-density polyethylene (LDPE) and nylon layered polyethylene (Ny/PE) film pouches or plastic and glass bottles, were compared during storage at 20 °C for 126 days. In the 7% moisture content sample packaged in LDPE film and plastic bottles, the L* and b*-values increased from 48.2 ± 0.7 and 15.4 ± 1.1 to 65.2-65.9 and 29.5-30.3, respectively, while the a*-value decreased from 26.1 ± 0.7 to 14.2-15.9, indicating a noticeable color change from red to orange. However, the decrease in the capsaicinoid and free sugar content of red pepper powder over time was found to have no significant correlation with moisture content and packaging type. As a result, the color change during the long-term storage of red pepper powder was greatly influenced by the initial moisture content and gas permeability of the packaging material.

Influence of the Drying Process on the Volatile Profile of Different Capsicum Species

Chili is a globally significant spice used fresh or dried for culinary, condiment, and medicinal purposes. Growing concerns about food safety have increased the demand for high-quality products and non-invasive tools for quality control like origin tracing and safety assurance. Volatile analysis offers a rapid, comprehensive, and safe method for characterizing various food products. Thus, this study aims to assess the impact of the drying process on the aromatic composition of various Capsicum species and to identify key compounds driving the aromatic complexity of each genetic makeup. To accomplish these objectives, the aroma was examined in fruits collected from 19 different pepper accessions (Capsicum sp.) belonging to four species: one ancestral (C. chacoense) and three domesticated pepper species (C. annuum, C. baccatum and C. chinense). Fresh and dried samples were analyzed using a headspace PTR-TOF-MS platform. Our findings reveal significant changes in the composition and concentration of volatile organic compounds (VOCs) from fresh to dried Capsicum. Notably, chili peppers of the species C. chinense consistently exhibited higher emission intensity and a more complex aroma compared to other species (both fresh and dried). Overall, the data clearly demonstrate that the drying process generally leads to a reduction in the intensity and complexity of the aromatic compounds emitted. Specifically, fresh peppers showed higher volatile organic compounds content compared to dried ones, except for the two sweet peppers studied, which exhibited the opposite behavior. Our analysis underscores the variability in the effect of drying on volatile compound composition among different pepper species and even among different cultivars, highlighting key compounds that could facilitate species classification in dried powder. This research serves as a preliminary guide for promoting the utilization of various pepper species and cultivars as powder, enhancing product valorization.

Comparative evaluation of ethylene oxide, electron beam and gamma irradiation treatments on commonly cultivated red chilli cultivars (Kunri and Hybrid) of Sindh, Pakistan

Chillies are considered a universal ingredient for imparting flavor and pungency to foods. Pakistan stood in the top twenty countries worldwide by producing 82 thousand Tons of chillies during 2022-23. Chilli fungal contamination and aflatoxin production during drying is a common problem during post-harvest process. Gasses treatment and Ionizing radiations are efficient methods for reducing toxigenic and pathogenic microbial growth in food items. The current study was designed to compare the effects of ethylene oxide (ETO), gamma (GB) & electron beam (EB) treatments on two red chilli local cultivars (Kunri and Hybrid) of Pakistan. After treatment, the chilli samples were analyzed for aflatoxins, physicochemical, quality & safety attributes. All results were subjected to Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), dendrogram and ANOVA to check the correlations, grouping and level of significance within the varieties and treatments. The results showed that moisture and water activity mainly designated PC-2 directions and are slightly positively correlated. Conversely, both fat and proteins have a negative correlation with moisture, ash and water activity. Besides, carotenoids and ABTS assay mainly designated PC-2 directions and are slightly positively correlated. Color, flavonoids and TPC also possess positive correlations among them. ETO depicts effectiveness in the reduction of E. coli but is not effective in saving antioxidant potential such as total flavonoids. Similarly, gamma irradiations showed strong reduction trends in fungal and pathogenic count, however same trend was observed in ascorbic acid too. Besides, the electron beam with dosage levels of 12 and 15 kGy has shown effectiveness against Aspergillus spp., aflatoxins and pathogenic microbial load in addition to saving antioxidant potential (phenolics and flavonoids), physicochemical parameters and color values compared to other applied methods especially in Kunri variety. It was evident from the research that varietal combination in addition to applied treatment must be specially considered while designing a treatment for chillies.

Promising effect of Geranium robertianum L. leaves and Aloe vera gel powder on Aspirin®-induced gastric ulcers in Wistar rats: anxiolytic behavioural effect, antioxidant activity, and protective pathways

BACKGROUND

Many drugs have been restricted in the treatment of gastric ulcers (GU). So, herbal medicines are now in great demand for their better cultural acceptability, compatibility, and minimal side effects. Therefore, our study aimed to assess the protective efficacy of Aloe vera gel and Geranium robertianum extracts against Aspirin®-induced GU in Wistar rats.

METHODS

Antioxidant activity and chemical composition of both herbs were analysed. Then, we divided forty female Wistar rats into five groups: a negative control group, a positive control group of Aspirin®-induced GU, and pretreated groups with Aloe Vera, geranium, and Famotidine (reference drug). The locomotor disability, anxiety-like behaviour, and ultrasonography were assessed. Ultimately, scarification of animals to determine gastric juice pH and ulcer index. Then the collection of stomach and liver for histopathological and immunohistochemical examinations, besides tracing the oxidative stress biomarkers and related genes.

RESULTS

High content of polyphenols was revealed in both extracts. The pretreatment with Aloe vera gel and geranium showed significant antioxidant activities with free radical scavenging and ferric-reducing power (FRAP). Moreover, they improved the stomach architecture and alleviated anxiety-like behaviour and motor deficits. They significantly reduced the expression of proinflammatory cytokine (TNF-α), inflammatory, and oxidative stress genes (NF-KB, HO-1, Nrf-2) while increasing the Keap-1 in gastric mucosa.

CONCLUSION

Data presented a significant protective effect of Aloe vera gel and geranium against Aspirin®-induced GU; they reduced gastric mucosal injury with potential anxiolytic effects through their anti-inflammatory and antioxidant properties. Therefore, they may be considered promising agents for preventing or treating gastric ulceration.

Effects of packaging and temperature abuse on the quality of red pepper (Capsicum annuum L.) powder

Storage stability of pepper (Capsicum annuum L.) powder packaged using 2 different film pouches of Ny/PE and PET/Al/PE inserted with moisture absorbent and oxygen scavenger was investigated during storage at 25 °C for 5 months and at 40 °C for 14 days. The moisture content of red pepper powder did not change significantly in PET/Al/PE packaging but decreased significantly in Ny/PE packaging after the abuse of storage temperature. The color of red pepper powder was quite stable in all packaging treatments. Other quality characteristics of all packaged pepper powder, including microbial cell count, capsaicinoids, ascorbic acid, and free sugar content, were also maintained near their initial levels with no appreciable changes during storage. Red pepper powder with a moisture content of 13-14% and packaged with a film with high gas-barrier properties can be stored for more than 5 months even if there is an unexpected temperature abuse during storage.

Effect of Foam-mat Drying on Bioactive, Powder and Thermal Properties of Carrot Juice Powders

Foam-mat drying is a promising method due to involvement of proteins as foaming agent which acts like a wall material wrapping around bioactives and retards their degradation. In this study, powder properties of foam-mat dried carrot juice powders including 15% egg albumen (EA) and 15% egg albumen+ 10% whey protein isolate (WPI) during 90 days of storage at room conditions were evaluated by means of physical, chemical, thermal (DSC and TGA) and microstructural (SEM) analyses. The powder flow properties (wettability, hygroscopicity, degree of caking, Carr index and Hausner ratio) have been significantly affected from the moisture uptake during storage; however, powder flow properties of 15% EA+ 10% WPI powders were found to be better than 15% EA powders as it was also confirmed by particle diameter distributions that remained the same before and after the storage period. Besides, the total antioxidant, phenolic and carotenoid contents of 15% EA+ 10% WPI carrot powder was found comparably higher than 15% EA powders due to possible encapsulating mechanism of whey proteins. In addition to delaying of physical and chemical deteriorations in powders with WPI incorporation, thermal stability of the foam-mat dried carrot juice powders was also improved in 15% EA+ 10% WPI powder.

Effects of different drying methods on the storage stability of barley grass powder

BACKGROUND

Barley grass (BG) powder has gradually attracted researchers' attention for its abundant nutritional components and functional activity. Yet, the effect of different drying methods on storage stability is still unclear. In this study, BG was subjected to hot-air drying (HAD), steam blanching prior to hot-air drying (SHAD), vacuum freeze drying (VFD), and far-infrared drying (FID). Effects of different drying methods on BG powder during storage were evaluated.

RESULTS

Moisture content of dried samples during storage decreased at 50 °C, but at 37 °C increased first and then remained stable. The a* value of SHAD BG powder before storage was the highest (-6.51), followed by FID, HAD and VFD. Moreover, the a* value increased during the storage process. Contents of l-ascorbic acid and total chlorophyll in samples dried by VFD were 28.29 and 7.8 g kg^-1 , respectively. The degradation of chlorophyll a and b followed a first-order kinetics model and was modeled by the Arrhenius equation. The activation energies for chlorophyll a were 83.68, 83.21, 62.29 and 76.64 kJ mol^-1 in BG powder dried by SHAD, FID, VFD and HAD, respectively. The activation energies for chlorophyll b were 66.76, 48.03, 61.02 and 58.01 kJ mol^-1 in SHAD, FID, VFD and HAD BG powder, respectively.

CONCLUSION

VFD had the highest preservation of color, l-ascorbic acid and chlorophyll compared to HAD, SHAD and FID. SHAD shortened the drying time and delayed the degradation of l-ascorbic acid and chlorophyll during storage. © 2021 Society of Chemical Industry.

Effect of Drying Whole and Half Chili Pods Using a Solar Dryer with CaCl2 Desiccant on Quality of Powder Chili

This study investigated the quality of dried whole and half chili pods' powder dried with solar drying combined with CaCl₂ desiccant compared with natural convection solar drying to produce the final chili powder product. Besides the sensory analysis, the quality parameters such as beta-carotene, moisture, vitamin C, and ash content were also observed. The results showed that 57 hours of drying time of whole and half chili pods using solar drying can reach moisture content below 5%. Beta-carotene, ash, and vitamin C contents of the whole chili were higher than those of half chili pods' dried pepper powder; they were20.38 ± 0.22 mg/100 g, 5.81 ± 0.15%, and 23.99 ± 0.57 mg/100 g, respectively. This study can guide the red chili drying process based on the quality of the dried chili powder.

Effect of gamma radiation and storage at 4°C on the inactivation of Listeria monocytogenes, Escherichia coli and Salmonella enterica Typhimurium in Legon-18 pepper (Capsicum annuum) powder

Objectives

Spices are low moisture foods which have been known to be contaminated with various pathogens and sun-dried Legon-18 pepper powder is not left out. Due to its contamination with various pathogens, a study was conducted to determine the effects of gamma irradiation on the decontamination of Legon-18 pepper powder and on some quality parameters.

Methods

Samples were obtained from a local farmer from the Eastern Region of Ghana. Sterility tests were carried out. The samples were inoculated with known cfu/ml of Escherichia coli, Listeria monocytogenes and Salmonella enterica Typhimurium. Samples were irradiated at 1, 2, 4, and 5 kilogray (kGy). Zero kilogray served as control (unirradiated). All samples were stored at 4oC for 60 days. Enumeration of the various pathogens was done in appropriate media. Some quality parameters were determined after irradiating unsterile samples at 5 kGy and 0 kGy served as control. Capsaicinoids and carotenoids were quantified using a high performance liquid chromatography. The samples were stored at 4oC for 8 weeks.

Results

A dose-dependent effect on the inactivation of the pathogens was observed (P < 0.05). Storage time affected the inactivation of the pathogens as well (P < 0.05). Complete inactivation of the pathogens was observed at 5 kGy at day 0. Capsaicin, dihydrocapsaicin and total capsaicinoid content of the samples irradiated at 5 kGy increased at 23.64%, 14.7 % and 20.95% respectively as compared with the contents of the unirradiated samples. A gamma irradiation dose of 5 kGy caused losses of 8.11%, 8.67% and 26.54% in capsanthin, beta carotene and beta cryptoxanthin respectively. Quality parameters measured reduced with storage (P < 0.05).

Conclusions

Gamma irradiation inactivated pathogens at 5 kGy. Lower doses used during the study could inactivate the pathogens but with time. All quality parameters and carotenoids quantified were affected by gamma irradiation and storage period (P < 0.05).

Effects of processing techniques on drying characteristics, physicochemical properties and functional compounds of green and red chilli (Capsicum annum L.) powder

This study was aimed to investigate the effect of processing techniques on the characteristics of green and red chilli powder. Four samples, such as pretreated green chilli paste (PTGP), pretreated green chilli longitudinal slit (PTGL), pretreated whole red chilli (PTWR) and untreated green chilli paste (UTGP), were prepared and dried at 60 °C in a cabinet dryer. The pretreatment was blanching in acetic acid solution and soaking immediately in a combined solution of Na₂S₂O₅ and CaCl₂. Pretreated samples took a shorter drying time than the untreated sample in reducing moisture content from 86.31 to 8%. Pretreatment before drying resulted in retaining total chlorophyll (~ 86%), phenolic compounds (~ 32%), green color, and pungency of chilli. Analysis result indicated that more than 60% retention of β-carotene was found while retention of ascorbic acid was comparable. Conclusively, this research reveals a good nutritional profile in cabinet dried green chilli powder, which may open the scope for commercial production.

Preservation of red pepper flakes using microwave-combined cold plasma treatment

BACKGROUND

Red pepper flakes are often contaminated with various microorganisms; however, any technologies aiming to decontaminate the flakes should also maintain their quality properties. This study investigated the effect of microwave-combined cold plasma treatment (MCPT) at different microwave power densities on microbial inactivation and preservation of red pepper flakes. Red pepper flake samples inoculated with spores of Bacillus cereus or Aspergillus flavus and without inoculation were subjected to MCPT at 900 W for 20 min at either low microwave power density (LMCPT, 0.17 W m^-2 ) or high microwave power density (HMCPT, 0.25 W m^-2 ).

RESULTS

The numbers of B. cereus and A. flavus spores on red pepper flakes after LMCPT and HMCPT were initially reduced by 0.7 ± 0.1 and 1.4 ± 0.3 log spores cm^-2 and by 1.5 ± 0.3 and 1.5 ± 0.2 log spores cm^-2 respectively and remained constant for 150 days at 25 °C. Immediately after HMCPT, the concentrations of capsaicin and ascorbic acid in the flakes were significantly lower than in untreated samples; however, no difference in concentration was detected during storage. Neither LMCPT nor HMCPT affected the antioxidant activity or color of the flakes during storage. LMCPT also did not affect the sensory properties and the concentrations of capsaicin and dihydrocapsaicin of the flakes, indicating its suitability in preserving their quality properties.

CONCLUSION

MCPT may provide an effective non-thermal treatment for food preservation which can improve the microbial safety and stability of red pepper flakes while maintaining intact their qualitative properties. © 2018 Society of Chemical Industry.

Phytochemical composition and in vitro antioxidant potential of Cynodon dactylon leaf and rhizome extracts as affected by drying methods and temperatures

The effect of five drying methods including shade drying (SHD), solar drying (SOD), and oven drying at 30 (OD30), 40 (OD40) and 50 °C (OD50) on the phytochemical composition and antioxidant potential of C. dactylon leaf and rhizome was assessed. Among drying methods, OD50 resulted in the shortest drying time (18.3 and 12 h for rhizome and leaf, respectively), when compared with SHD and SOD. Based on GC-MS analyses, 15 and 17 constituents were identified in leaf and rhizome extracts, respectively, accounting for ~ 99% of all components. Fatty acids (palmitic acid and linoleic acid) along with their methyl esters (ethyl palmitate, ethyl linoleate and ethyl oleate) and other derivatives (dihomo-γ-linoleic acid) were the main identified constituents shortly after drying procedures; however, other components such as 5-hydroxymethylfurfural, maltol, retinol and phytol were also traced. Some of C. dactylon phytochemicals including 5-hydroxymethylfurfural and ethyl linoleate were sensitive to high drying temperatures. Besides, higher drying temperatures lead to the production or increasing the level of substances such as 2,3-dihydrobenzofuran, tricyclopentadeca-3,7-dien and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one and diacetin. Based on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, the IC50 values were generally higher (significance level of 0.05) for oven-dried rhizome compared with shade-dried leaves and rhizomes that quenched more than 84% of the DPPH at the concentration of 400 mg/ml (IC50 59.12). Our findings suggest that OD30 is a versatile drying method not only to reduce drying time but also to preserve the main phytochemicals and antioxidant activity of C. dactylon during dehydration.

Cu Nanoparticles in Hydrogels of Chitosan-PVA Affects the Characteristics of Post-Harvest and Bioactive Compounds of Jalapeño Pepper

Peppers are consumed all over the world due to the flavor, aroma, and color that they add to food. Additionally, they play a role in human health, as they contain a high concentration of bioactive compounds and antioxidants. The treatments used were an absolute control, Cs-PVA, and four treatments with 0.02, 0.2, 2, and 10 mg (nCu) g⁻¹ (Cs-PVA). The application of Cu nanoparticles in chitosan-PVA hydrogels increases the content of capsaicin by up to 51% compared to the control. This application also increases the content of antioxidants ABTS [2,2′-azino-bis (3-ethylbenzothiazolin-6-sulfonic acid)] and DPPH (2,2-diphenyl-1-picrylhydrazyl), total phenols and flavonoids (4%, 6.6%, 5.9%, and 12.7%, respectively) in jalapeño pepper fruits stored for 15 days at room temperature; under refrigeration, it increases DPPH antioxidants, total phenols, and flavonoids (23.9%, 1.54%, and 17.2%, respectively). The application of Cu nanoparticles in chitosan-PVA hydrogels, even when applied to the substrate, not only has an effect on the development of the jalapeño pepper crop, but also modifies the post-harvest characteristics of the jalapeño pepper fruits.

Physicochemical properties and sensory evaluation for the heat level (hot taste) of korean red pepper powder

This study investigated the heat level rating of several varieties of Korean red peppers. The chemical constitution of Korean red pepper samples were as follows: 0.54∼290.15 mg% capsaicinoids, 79.22∼139.09 ASTA value, and 16.76∼29.92% free sugar content. The heat level of the Korean red pepper samples was evaluated by trained panelists and the correlation coefficient and F value (0.001%) of the panelist's results were determined to be significant. In the principle component analysis (PCA), PC1 (capsaicinoids) and PC2 (free sugar) were shown to represent 31.98% and 25.77% of the total variance, respectively. The results of panelists trained for red pepper heat rating were evaluated using analysis of variance and correlation analysis. The trained panelists showed a high F value (p=0.05) and high correlation coefficient. A high correlation efficient of 0.84∼0.93 for the test samples with a 40 Scoville heat unit (32,000 SHU red pepper powder) was reported in the sensory evaluation of the Korean red pepper heat level by a trained panel. However, the panel showed a low correlation efficiency of 0.70 R(2) when the 60 SHU test samples were included in the analysis.