Shiitake mushrooms are prized for their unique flavor and bioactive properties. While there has been extensive research on drying methods, a comprehensive investigation of the effects of drying parameters in the dry-moist-heat system on shiitake quality is still needed. This study aimed to investigate the effects of dry-moist-heat aging on dried shiitake mushrooms comprehensively. Four aging temperatures, specifically 50, 60, 70, and 80 °C, were applied to the mushrooms, maintaining a constant humidity level of 75% RH and aging duration of 20 days. Color analysis revealed a progressive decrease in measured values as aging temperature increased, indicating noticeable changes in visual characteristics. Regarding amino acid composition, glutamic acid was found to be the predominant amino acid in shiitake mushrooms in the range of 90.29–467.42 mg/100 g. However, aging led to a reduction in overall amino acid content, with higher aging temperatures resulting in greater decline. Similarly, the equivalent umami content (EUC) also decreased (from 123.99 to 7.12 g MSG/100 g) with the increase in aging temperatures up to 80 °C, suggesting a decline in the overall umami taste sensation. Interestingly, despite the reduction in amino acid levels and umami content, the aging process positively impacted the phenolic compounds and the antioxidant activity of dried shiitake mushrooms. The antioxidative abilities of all aged mushroom extracts for DPPH, ABTS, and FRAP ranged from 65.01 to 81.39 µg TE/mL, 87.04 to 258.33 µg GAE/mL, and 184.50 to 287.68 µg FeSO₄/mL, respectively. The utilization of aged temperature at 60 °C for 20 days with controlled relative humidity (~75%) should be a suitable aging condition of this edible mushroom with both antioxidant and umami qualities. Nevertheless, the control sample demonstrated higher levels of amino acid content and EUC compared to the aged samples. Conversely, the aged samples exhibited higher polyphenol content and greater antioxidant activity. Depending on specific requirements, these powders can be used in food formulation as flavor enhancers for control samples or as enriching agents for polyphenols and antioxidant activity in matured samples. Therefore, all of the powders obtained have potential applications in the field of nutrition. Full article

Fenugreek seeds are a rich source of bioactive compounds, such as diosgenin, which is one of the most crucial steroidal sapogenins emerging in the field with its spectacular health benefits. Plant-based diosgenin is bitter in taste and has remarkably low consumption levels, making it unable to fulfil the role of improving health benefits. Diosgenin is spray dried to mask bitterness and astringent flavors with two different wall materials, such as maltodextrin (MD) and whey protein concentrate (WPC), separately. The spray-drying condition of the selected optimization process was inlet air temperature (IAT 150–170 °C), feed flow rate (FFR 300–500 mL/h), and carrier agent concentration (CAC 10–20%). The optimization of the process variable was conducted for producing optimized encapsulated diosgenin powder (EDP) with both MD and WPC. The selected parameters, such as yield, encapsulation efficiency, moisture content, antioxidant activity, hygroscopicity, and solubility, are investigated in this current work. Based on the experimental results, the significant R² values depict the model fitting to the responses. EDP revealed an optimization condition at 170 °C IAT, 500 mL/h FFR, and 20% CAC for MD and WPC. The highest responses were observed with WPC-EDP, such as yield at 82.25%, encapsulation efficiency at 88.60%, antioxidant activity at 53.95%, and hygroscopicity at 12.64%. MD-EDP revealed higher solubility at 96.64% and moisture content at 2.58%. EDP was studied using micrographs and diffractograms for the optimized samples, which revealed a smooth and dented surface with an amorphous nature for MD-EDP and WPC-EDP, respectively. EDP exhibited acceptable powder properties with regard to fulfilling the set purpose. EDP can be a better potential ingredient in different food matrices to act as a delivery vehicle for various health aliments. Full article

Pepper (Capsicum spp.) is among the oldest and most cultivated crops on the planet. Its fruits are widely used as natural condiments in the food industry for their color, flavor, and pungency properties. Peppers have abundant production; on the other hand, their fruits are perishable, deteriorating within a few days after harvesting. Therefore, they need adequate conservation methods to increase their useful life. This study aimed to mathematically model the drying kinetics of smelling peppers (Capsicum chinense) and pout peppers (Capsicum chinense Jacq.) to obtain the thermodynamic properties involved in the process and to determine the influence of drying on the proximal composition of these peppers. Whole peppers, containing the seeds, were dried in an oven with forced air circulation, at temperatures of 50, 60, 70, and 80 °C, with an air speed of 1.0 m/s. Ten models were adjusted to the experimental data, but the Midilli model was the one that provided the best values of coefficient of determination and lowest values of the mean squared deviation and chi-square value in most of the temperatures under study. The effective diffusivities were well represented by an Arrhenius equation, appearing in the order of 10⁻¹⁰ m²·s⁻¹ for both materials under study, since the activation energy of the smelling pepper was 31.01 kJ·mol⁻¹ and was 30.11 kJ·mol⁻¹ in the pout pepper, respectively. Thermodynamic properties in both processes of drying the peppers pointed to a non-spontaneous process, with positive values of enthalpy and Gibbs free energy and negative values of entropy. Regarding the influence of drying on the proximal composition, it was observed that, with the increase in temperature, there was a decrease in the water content and the concentration of macronutrients (lipids, proteins, and carbohydrates), providing an increase in the energy value. The powders obtained in the study were presented as an alternative for the technological and industrial use of peppers, favoring obtaining a new condiment, rich in bioactives, providing the market with a new option of powdered product that can be consumed directly and even adopted by the industry as a raw material in the preparation of mixed seasonings and in the formulation of various food products. Full article

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. Full article

The aim of this study was to compare the refractance window drying method (RWD) with the hot air oven drying (HD), vacuum drying (VD), and freeze-drying (FD) methods in order to analyze the outcomes of the qualitative properties of dragon fruit slices and pulp. Moreover, the impact of temperature on the phenolic content, antioxidant activity, color, and texture of the dragon fruit slices and pulp were studied. The results showed that the RWD samples exhibited a high nutritional quality in contrast to the other drying methods. The RWD method had a short drying time of 960 min to reach the final moisture content of 6.50% (dry basis), while the FD, VD, and HD methods had significantly higher drying times of 1320, 1200, and 1080 min, respectively, to reach the final moisture content. Higher values of TPC (182 mg GAE/100 g) and crude fiber (0.98%) were obtained in the RWD dragon fruit samples, indicating the potential of RWD to preserve the quality of dried samples. In conclusion, this study revealed that RWD provides an appropriate drying temperature as an alternative to freeze-drying. RWD may improve dragon fruit drying, adding value to the food industry. Full article

Effects of vacuum freeze drying (VFD), air impingement drying (AID), hot air drying based on temperature and humidity control (TH-HAD), pulsed vacuum drying (PVD), and medium- and short-wave infrared radiation drying (MSIRD) on the drying characteristics and physicochemical properties of garlic slices were investigated in the current work. Based on the experimental results, the Weibull model fitted the experimental results better (R² > 0.99) than the Wang and Singh model. Samples dried with PVD showed the smallest color difference (ΔE*), better rehydration capacity and desirable reducing sugar content. In response to thermal effects and pressure pulsations, the cell walls gradually degraded, and the cell and organelle membranes ruptured. The allicin and soluble pectin contents of garlic slices treated with PVD were higher by 8.0–252.3% and 49.5–92.2%, respectively, compared to those of the samples dried by other techniques. VFD maintained a complete garlic slice structure with the minimum shrinkage and the best appearance. The MSIRD process produced the densest structure, and caused an additional loss of color and phytochemical contents. The findings in current work implied that PVD could be a promising drying technique for garlic slices. Full article

Ginger is one of the most popular spices and medical herbs with its unique pungent flavour and taste. Although there has been much research into the drying methods of ginger, the effect of drying parameters in hot air convective drying on ginger quality needs to be explored in depth. This study investigated the differences in drying behaviour and quality characteristics of ginger with the variables of temperature, thickness, and loading density. The moisture states and diffusion pattern in the different stages during the drying process were analysed using low-field NMR techniques. The results of quality evaluation showed that the temperature greatly influenced the colour and gingerol content of dried ginger, and the thickness of a ginger slice greatly influenced the rehydration rate. Optimal drying conditions were determined by considering a combination of specific energy consumptions with quality retention based on the response surface methodology: a temperature of 66.41 °C, thickness of 2 mm, and loading density of 5 kg/m². HS-GC-IMS combined with multivariate chemometrics was used to achieve the characterisation of flavour profiles and fingerprinting of dried ginger. The principal component analysis and correlation analysis revealed that the alterations in ginger quality were intimately related to moisture diffusion during drying. Full article

Gum and mucilage from seeds and fruits are objects of study because they have characteristics of high viscosity at low concentrations and gelling properties, which are useful characteristics for modifying the texture and stabilizing products in the food industry. Chia and okra have high concentrations of polysaccharide gums in their composition, which makes them an interesting target for use in the composition of foods that require the use of texture enhancers and stabilizers. The present study investigated the influence of dehydration temperature on the characteristics of chia and okra powder mucilage obtained at different temperatures. The mucilages were extracted using an aqueous process and dehydrated in an air circulation oven at 50, 60, and 70 °C until hydroscopic equilibrium. Then, the powdered chia mucilage (CM) and okra mucilage (OM) were analyzed for chemical and physicochemical characteristics, bioactive compounds, antioxidant activity, and physical properties. It was found that powdered mucilage had low water content and water activity, with CM standing out in terms of ash, pectin, and starch content and OM, along with higher averages of proteins, sugars, total phenolic compounds, anthocyanins, flavonoids, and antioxidant activity. As for the physical parameters, CM stood out in relation to greater solubility and lower hygroscopicity, whereas OM presented higher wettability rates. Both powdered mucilages were classified as having good fluidity and cohesiveness from low to intermediate. In relation to the dehydration temperature, the best mucilage properties were verified at 70 °C. The study revealed that mucilages have good functional properties offering great potential as raw material for industry. Full article

Pomegranate is a fruit desirable for its nutritional and medicinal properties which has a great industrial potential that is yet under-explored. Notable for its integral use, the peels are used in medicinal infusions and the seeds consumed without restrictions. In this sense, the objective of this work is to determine the drying kinetics of pomegranate peels and seeds in a hot air circulation oven, at temperatures of 50, 60, and 70 °C, adjust mathematical models to experimental data, determine the effective diffusivities and thermodynamic properties of the process and the physicochemical characteristics of peels and seeds of fresh pomegranates and in their flours. Twelve models were used to adjust the drying kinetics, obtaining better results with the Diffusion Approximation model, Verma, and modified Henderson and Pabis. The effective diffusivities were well represented by an Arrhenius equation, with activation energies of 31.39 kJ/mol for seeds and 10.60 kJ/mol for peels. In the drying process, the seeds showed higher values of enthalpy, entropy, and Gibbs free energy concerning peels. Pomegranate peel and seed flours have proximal composition and distinct physicochemical characteristics, with high fiber, carbohydrate, and energy content. In addition, peel flours stand out for their mineral content, and seed flours do for their lipid and protein content. Full article

Considering the solar radiation status in Oman, a low-cost, indirect, stand-alone, forced-convective solar dryer was developed to dry medicinal herbs, which are sensitive to direct sun. The hot air flow was obtained using a solar-panel-powered blower and air passing through a black-body solar collector. This drying process could extend the shelf life of herbs while preserving their medicinal and nutritional (physicochemical) properties and adhering to food safety and hygiene practices. This study investigated the benefits of an indirect solar drying technique on the retention of quality attributes of mint and basil used in medicinal applications. Herbs used during drying could be subjected to changes in their physicochemical properties such as color, water activity (Aw), total soluble solids (TSS), phenol content, antioxidant capacity, and moisture content (MC), and, thus, results were compared with fresh herb samples. The dryer chamber-maintained temperature and relative humidity regimes of 30–50 °C and 21–95% and the expected final moisture content (wet basis) was 10%. The dryer showed improved physicochemical quality parameters and the retention of green color with parameter ranges of Aw 0.44–0.63, phenol content (increase) 1705–8994 mg/100 g DM, and antioxidant capacity (increase) 0.61–0.67 µmol/g DM, respectively. This study showed the ability of developed solar dryers to preserve the physicochemical properties of medicinal herbs during drying and can extend to other food products. Full article