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Drying herbs is a crucial method for stabilizing and preserving their essential properties and bioactive compounds. Although freeze drying is the preferred method for most herbs, it is expensive due to high energy consumption and operating costs. Biflavonoids are dimeric flavonoids that have recently been recognized as potential molecules possessing biological activities, such as antiviral and antimicrobial activity, and as effective molecules for the treatment of neurodegenerative and metabolic diseases and for cancer therapies. In this study, we performed a comparative analysis of freeze drying, air drying and oven drying to evaluate their effects on biflavonoid content in yellow ginkgo leaves (Ginkgo biloba L.). After drying, we performed spectrophotometric analysis to determine the browning index, pigments, phenolic compounds and antioxidant activity, while HPLC-DAD was used for the identification and quantification of individual biflavones (amentoflavone, bilobetin, ginkgetin, isoginkgetin and sciadopitysin). The most abundant biflavonoids were isoginkgetin and bilobetin, the amounts of which exceeded 1000 µg/g dw in all leaf samples. They were followed by ginkgetin and sciadopitysin, the amounts of which were about 30% lower. The drying method did not influence biflavone content or the total carotenoids, total polyphenols and total flavonoids. Consequently, our study suggests that all three methods may be used for the preparation of yellow ginkgo leaves as a source of biflavones and other bioactive compounds.

Almond bagasse resulting after the production of almond-based drinks represents a promising by-product with potential for use as a functional ingredient. To facilitate its utilization, the stability of this material can be achieved through dehydration processes such as hot air drying or freeze-drying. Nevertheless, owing to its high fat content, almond bagasse is prone to lipid oxidation, which could result in undesirable quality. Therefore, the objective of this work was to assess the impact of dehydration (by hot air drying at 60 and 70 °C and by freeze-drying) and storage (at room temperature and in accelerated conditions) on the functional quality and stability of almond bagasse powder. Throughout the dehydration process, it was observed that antioxidant compounds were preserved without significant differences among dehydration treatments. These compounds increased over the storage period, especially in the samples treated with hot air. Regarding antiradical capacity, the hot-air-dried samples showed higher values than the freeze-dried ones, although in all cases, it increased during storage. For total phenols in samples air-dried at 70 °C, increases of more than 50% were observed. The acidity and peroxide index were increased in the extended storage period, although they did not reach critical values. Samples stored for 180 days showed peroxide values ranging from 10 to 12.8 meq O2/kg dry matter for samples stored at room temperature and from 14.7 to 23 meq O2/kg dry matter for samples subjected to accelerated storage.

Fresh and dried Cordyceps sinensis are widely used by the public for medicinal and health purposes. However, the differences between them have not been examined. In this study, fresh wild and artificial C. sinensis (WFC and AFC) were dried to obtain dried wild and artificial C. sinensis (WDC and ADC). Non-targeted GC-MS was used to analyze the metabolic profile characteristics of the four groups of samples. The results showed that air drying significantly altered the composition and content of C. sinensis, mainly in the form of higher abundance of organic acids and derivatives and lower abundance of lipids and lipid-like molecules in fresh C. sinensis. Hierarchical cluster analysis (HCA) and quantitative analyses showed that air drying increased the abundance of Valine, Zinniol, Urocanate, Vulpinic acid, and Uridine 5’-diphosphate, and decreased Xanthotoxol, Vitexin-4-o-glucoside, Val-trp, and Wogonin. These differentially accumulated metabolites (DAMs) were also shown to be potential biomarkers for C. sinensis. KEGG enrichment analysis identified lysine biosynthesis as the most significantly enriched pathway. Annotation of these DAMs to lysine biosynthesis revealed that citrate cycle and pyruvate metabolism entered lysine biosynthesis via 2-oxohlutarate and Homocitrate, respectively, resulting in significant enrichment of L-saccharopine and L-lysine content was significantly higher. Alanine, aspartate, and Glutamate metabolism synthesized more L-aspartate to promote L-lysine synthesis. Thus, high levels of L-lysine result in lysine degradation and pymolysine, which are the most active metabolic pathways during the drying of fresh C. sinensis and indirectly lead to differences in metabolic profiles.

In this study, solid olive mill waste (SOMW) was used to obtain antioxidant compounds using solid–liquid extraction. The effect of different extraction methods, namely microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), Soxhlet, and conventional solvent extraction, on the yield, total phenolics, and total antioxidant activity of SOMW extracts was investigated. Untreated and dried SOMW were subjected to extraction with water and methanol. The antioxidant activity of the extracts was evaluated using the DPPH assay, while their total phenolic content was measured using the Folin–Ciocalteu method. For the characterisation of the extracts, HPLC-DAD analysis was performed. The results showed that the extraction yield was significantly influenced (p < 0.05) by the solvent used, the material treatment prior to extraction, the moisture content of SOMW samples, and the extraction time. The optimised parameters were water, as the extraction solvent, and MAE as the extraction technique (extraction temperature of 50 °C and time of 1 h). The evaluation of the antioxidant activity of the extracts indicated that phenolics were the dominant bioactive compounds. The extracts were found to be rich in several hydroxytyrosol derivatives. Therefore, SOMW can be a valuable resource for bioactive compounds using conventional and innovative extraction techniques.

Elderflower extracts are known to be a source of valuable substances that show a wide spectrum of biological activity, including antibacterial and antiviral properties, which demonstrate a degree of effectiveness against SARS CoV-2. In this work, the influence of fresh inflorescence stabilisation methods (freezing, air drying, and lyophilisation) and extraction parameters on the composition and antioxidant properties of the extracts were studied. Wild elderflower plants growing in the Małopolska Region of Poland were studied. Antioxidant activities were evaluated by 2,2-diphenyl-1-picrylhydrazyl free radical-scavenging ability and ferric-reducing antioxidant power assays. The total phenolic content was determined using the Folin-Ciocalteu method and the phytochemical profile of the extracts was analysed using HPLC. The obtained results showed that the best method for the stabilisation of elderflower was lyophilisation, and the determined optimal maceration parameters were 60% methanol as a solvent and a process time of 1–2 days.

Būt (Sideroxylon mascatense) is an indigenous wild blueberry found in Oman. It has a very short season and is commonly preserved by drying. The aims of this study were to determine the physico-chemical characteristics and stability of phytochemicals (i.e., polyphenols and flavonoids) in the berries during drying (i.e., freeze-drying at −40 °C and air-drying at 60 and 90 °C) and the polyphenol stability of the dried berries as a function of storage temperature (i.e., 90, 70, 60, 40, 20, and −20 °C). The moisture content of fresh berry flesh was 64.5 g/100 g sample (wet basis). The crude protein and fat contents were higher in the seeds than in the flesh. Glucose and fructose were the main sugars and their concentrations were highest in the sample air-dried at 60 °C. The initial total polyphenol content (TPC) and total flavonoid content (TFC) of the flesh were 2.009 mg gallic acid equivalent (GAE)/g dry-solids and 0.199 mg catechin equivalent (CE)/g dry-solids, respectively. The samples air-dried at 90 °C and freeze-dried at −40 °C had higher TPC (i.e., 2.638 mg GAE/g dry-solids) and TFC (i.e., 0.395 mg CE/g dry-solids), respectively. There was a significant difference between the TPC and TFC of fresh and dried wild berries (p < 0.05). The freeze-dried wild berries retained a high TPC compared to the air-dried samples. The polyphenol storage stability of freeze-dried wild berries at different storage temperatures showed two phases: an initial release phase followed by a decay phase. The polyphenol storage stability was modeled using the Peleg model and the kinetic parameters were correlated with the storage temperature.

The shrinkage of the connective tissue and myofiber of lamb meat submitted to heat treatment or air drying at different storage stages (1, 5 and 7 days) was evaluated herein. The longitudinal and transverse shrinkage of heated lamb meat was significantly influenced by storage time and water bath heating temperature (50 °C, 70 °C and 90 °C) (p < 0.001). In contrast, the shrinkage of air-dried lamb meat was not influenced by storage time (p > 0.05). The microstructure of heated lamb meat, namely, the distance between muscle fascicles, the distance between myofibril networks, the area of myofibril networks, and the endomysium circumference, was significantly influenced by storage time (p < 0.05). During storage, the proportion of muscle fibers completely detached from endomysium increased, which could be due to the progressive degradation of proteins linking the endomysium and myofibril, including β-dystroglycan, α-dystroglycan, integrin-β1, and dystrophin. However, degradation of such proteins did not influence the shrinkage of lamb meat stored for five days or longer, since the decreased distance between myofibril networks indicated a higher shrinkage ratio of the endomysium compared to myofibers in samples air-dried at 35 °C or heated at 90 °C. The effect of these proteins on the shrinkage of heated lamb meat (raw meat stored for 1 day or less time) requires further elucidation.

Sediment humic substance (SHS) is a highly heterogeneous and complex organic mixture with a broad molecular weight range. It is the significant component that associates distribution, transport, and biotoxicity of pollutants in a river environment. Air- and freeze-drying sediment pre-treatment may cause different biological activity and may result in different chemical quantities and sediment organic matter. This study collected sediments that received livestock wastewater discharge. The sediments were air- (AD) and freeze-dried (FD). The dried sediment organic matter was extracted with an alkaline solution and separated into three size-fractioned SHS samples. Size-fractioning is an effective method used to differentiate materials, on a molecular level. The bulk solution (254) and an extent of humification (HIX) than the FD SHS. In addition, the high molecular weight SHS (HHS) had a higher SUVA254 but lower HIX than the MHS and LHS. The HHS had significantly lower fulvic acid but had higher humic acid-like substances than the MHS and LHS. This is possibly the reason the LHS had a higher humification degree but lower aromaticity than HHS. The size-fractioned SHS and optical indicators distinguished the difference between the chemical properties when air- or freeze-dried, due to the different degree of biological activities.

Radiant Energy Vacuum (REV)-dried broccoli, oranges, and carrots prepared by the optimal drying protocols determined in this study were compared to the freeze-dried and air-dried samples based on the nutritional values before and after drying. An accelerated shelf-life study for REV-dried broccoli, oranges, and carrots was also conducted. For all the samples, REV drying significantly shortened the processing time. The REV-dried samples had much higher retention of the nutritional values (vitamin C, β-carotene) compared to the conventional air-drying process, and the values were also competitive to those of the freeze-dried samples. Although freeze-drying resulted in the best rehydration property, the REV-dried samples still earned the highest scores in the sensory test. In the accelerated shelf-life study conducted on the REV-dried samples, the moisture content and water activity stayed at the same level, but the nutritional values showed a downward trend. The sensory properties fluctuated in the shelf-life but still gained positive feedback from the panelists. Moreover, the testing method for β-carotene content was uniquely designed in this project and could be a semi-quantitative method to refer to.

The physico-chemical and microstructural changes of “Rojo Brillante” persimmons in two maturity stages (S1 and S2) were evaluated during air drying. The maturity stage influences moisture loss. A Moisture level of approximately 50%, a limit at which persimmons are considered semidried, was reached after 21 and 28 days for S1 and S2, respectively. Shrinkage resulting from water removal led to secondary epidermis formation concomitantly to internal flesh gelling, which was related to moisture loss and water activity changes of each fruit part. The thicker epidermis and the lower volume of gelled area inside the S1 fruits led to harder fruit compared to the S2 fruits. The microstructural study revealed parenchyma degradation during drying in both the outermost area (secondary epidermis) and internal flesh, and this process was faster in S1 than in S2. The second peel presented hollows, generated by water outflow, which were bigger in S1 and explained the faster internal dehydration in S1. During drying, slight browning occurred, as reflected in the declining color parameters (L*, h* and C*). Water removal led to soluble solids tannin reduction to non-astringency values on day 28.