Search Results (85)

This study aimed to evaluate the effects of three drying methods, namely sun drying, microwave–vacuum drying, and hot-air-oven drying, on the physical and nutritional properties of cricket powder for use in poultry feed. The results showed that the drying method significantly affected color parameters (L*, a*, and b*; p < 0.05), and particle size distribution at 850 µm and 250 µm (p = 0.04 and p = 0.02, respectively). Microwave–vacuum drying produced the lightest powder with a higher proportion of coarse particles, while sun drying resulted in a darker color and greater particle retention at 850 µm. Hot-air-oven drying yielded the lowest moisture content (1.99%) and the highest gross energy (6126.43 kcal/kg), with no significant differences observed in crude protein (p = 0.61), ether extract (p = 0.08), crude fiber (p = 0.14), ash (p = 0.22), or amino acid profiles (p > 0.05). These findings indicate that all drying methods preserved the nutritional value of cricket powder, and based on the overall results, hot-air-oven drying is the most suitable method for producing high-quality cricket meal with optimal physical properties and feed value, while also providing a practical balance between drying efficiency and cost. Full article

Grain drying technology is a core process for ensuring food quality, extending storage life, and improving processing adaptability. With the continuous growth of global food demand and the increasing requirements for food quality and energy efficiency, traditional drying technologies face multiple challenges. This paper reviews six major grain drying technologies, comprising hot air drying, microwave drying, infrared drying, freeze drying, vacuum drying, and solar drying. It provides an in-depth discussion of the working principles, advantages, and limitations of each technology, and analyzes their performance in practical applications. In response to challenges such as high energy consumption, uneven drying, and quality loss during the drying process, the paper also explores the research progress of several hybrid drying systems, such as microwave–hot air drying combined systems and solar–infrared drying systems. Although these emerging technologies show significant potential in improving drying efficiency, energy saving, and maintaining food quality, their high costs, scalability, and process stability still limit large-scale applications. Therefore, future research should focus on reducing energy consumption, improving drying precision, and optimizing drying system integration, particularly by introducing intelligent control systems. This would maximize the preservation of food quality while improving the system’s economic efficiency and sustainability, promoting innovation in food production and processing technologies, and further advancing global food security and sustainable agricultural development. Full article

American ginseng (Panax quinquefolium L.) residue from the extraction industry can be dried and mixed with rice bran as media for black truffle solid-state fermentation to enhance reuse and bioactive functions. Different ratios of rice bran (R) and American ginseng residue (G) mixtures were used as solid-state media for 5 weeks of black truffle fermentation, and then their bio-component contents and whitening effects were analyzed. Finally, four drying methods—hot air drying (HA), microwave drying (MW), hot air-assisted radio frequency (HARF) drying, and radio frequency vacuum (RFV) drying—were assessed to optimize drying efficiency for fermented medium. The results showed that using a 3:1 ratio of rice bran and American ginseng residue as the medium increased the crude polysaccharide and flavonoid contents by approximately threefold and enhanced the ginsenoside Rg3 content about twelvefold. Additionally, the 100 µg/mL ethanol extract of the fermented product inhibited 70% of tyrosinase activity and reduced the melanin area on zebrafish embryos by 42.74%. In the drying study, RFV drying R2G1 required only 13 min without exceeding 70 °C, demonstrating superior drying efficiency, temperature control, and low energy consumption. Overall, this study demonstrates the potential of black truffle fermentation of solid-state media from rice bran and American ginseng residue mixtures for whitening applications and highlights RFV drying as an efficient method for by-products. Full article

In general, the acceptance of edible insects by consumers is low. Therefore, the aim of this research was to develop protein supplements from desiccated crickets. The objectives of this research were to study the effects of four different drying methods on the chemical properties of crickets and the effects of cricket powder fortification in vegetable chips on the chemical and physical qualities and consumer acceptance. Through an analysis of the chemical composition of cricket powder dried using hot air, vacuum, microwave, and freeze-drying methods, it was found that freeze-drying resulted in the highest protein content in the cricket powder, followed by vacuum drying, hot air drying, and microwave drying. However, the antioxidant activity, which was analyzed using DPPH, showed no significant differences across the four drying methods (p > 0.05). The sensory testing of chips by 30 consumers revealed that the chips with a 10:10 ratio of vegetable powder to cricket powder received the highest satisfaction results in all of the test attributes, ranging from “like” to “like very much”. When studying the chemical composition, hardness, and color of the chips, it was found that increasing the amount of cricket powder resulted in a decrease in lightness and yellowness, while redness and hardness increased. The antioxidant activity and phenolic content of the chips increased with the addition of cricket powder, while the flavonoid and potassium contents decreased as vegetable powder was replaced with cricket powder. In the formula most preferred by consumers, the antioxidant activity, phenolic content, flavonoid content, and potassium content were 60.90%, 6.25 ± 0.46 mg GAE/mg sample, 11.16 ± 0.1 mg QE/mg sample, and 0.66 ± 0.01%, respectively. Full article

Star anise, a traditional seasoning, plays a significant role in influencing consumer preferences through its flavor release during cooking. This study examines how drying techniques—hot air drying (HAD), heat pump drying (HPD), Far-infrared drying (FIRD), and microwave vacuum drying (MVD)—affect the visual appearance and flavor release of star anise. Among these techniques, HAD required the longest drying time (20.5 h) and had the highest fracture rate (11.97%), while MVD achieved the shortest drying time (70 min) and FIRD had the lowest fracture rate (9.84%). Color analysis of dried star anise fruits revealed no significant differences among HAD, HPD, and FIRD (p* > 0.05), but MVD resulted in poorer color quality. Following boiling, 26 aroma compounds were identified, with trans-anethole and anisic aldehyde being the most prominent. Compared to other techniques, HPD exhibited the highest volatile oil content and trans-anethole levels in star anise after cooking. Overall, HPD produces star anise with superior visual quality and enhanced flavor release during cooking, making it a more suitable option for large-scale drying. Full article

In this study, the compositional shifts in free and bound phenolic compounds of Morinda citrifolia L. (Noni) processed by different drying methods were investigated. Twenty-seven phenolic compounds, predominantly rutin and quinic acid, were discovered in fresh Noni fruit. Vacuum freeze-drying retained the highest free phenolic content, with rutin (1809.83 mg/kg DW) and quinic acid (198.72 mg/kg DW) as the primary constituents, while bound phenolics were dominated by benzoic acid (35.56 mg/kg DW). Hot-air drying reduced the free phenolics by 51.59% (80% methanol) and the bound phenolics (base hydrolysis) by 35.55%, with a significant degradation of rutin and quinic acid. Microwave drying similarly decreased the free phenolics, though the caffeic acid increased to 46.45 mg/kg DW due to the thermal stability. Bound phenolics showed the highest content (alkaline hydrolysis) in fresh fruits, primarily benzoic acid (220.67 mg/kg DW) and rutin (77.02 mg/kg DW), surpassing the acid/enzyme methods. While vacuum freeze-drying effectively preserved the free phenolics, thermal methods (hot-air/microwave drying) promoted the release of quercetin (free phenols) and 3,4-dihydroxybenzoic acid (bound phenols). The findings of this study elucidate the species-specific compositional dynamics of phenolic compounds under different drying regimes, while providing quantitative guidelines for advancing the understanding of the underlying health-promoting phytochemical profiles of Noni. Full article

Acanthopanax senticosus (Rupr. and Maxim.; AS) fruit, an underutilized byproduct, possesses significant bioactive potential, yet its quality is highly influenced by drying methods. This study systematically evaluated the effects of five drying techniques, including vacuum freeze-drying (VFD), vacuum drying (VD), microwave drying (MD), hot-air drying (HD), and natural drying (ND), on the color retention, bioactive composition, volatile profile, and antioxidant activity of AS fruit. VFD preserved the highest levels of total phenolic content (TPC) and total flavonoid content (TFC), particularly chlorogenic acid, rutin, and quercitrin, leading to superior antioxidant activity. Amino acid analysis indicated that VFD retained the highest concentrations of key essential amino acids, minimizing thermal degradation. Correlation analysis revealed a strong association between TPC, TFC, and antioxidant activity, emphasizing their functional significance. Through multivariate statistical analysis, 12 volatile compounds were identified as potential biomarkers to distinguish AS fruit samples processed using different drying methods, highlighting significant metabolic differences between drying techniques. Overall, VFD emerged as the optimal method for preserving AS fruit’s bioactive integrity, offering valuable insights for post-harvest processing strategies in the nutraceutical industry. Full article

This study investigated the impact of four drying techniques—hot air drying (HAD), vacuum hot air drying (VFAD), microwave drying (MWD), and vacuum freeze-drying (VFD)—on the structural, physicochemical, and functional properties of scallop adductor muscles, a critical marine resource in the food industry. The results demonstrated that VFD optimally preserved the ultrastructural integrity of the tissue, maintaining its surface fibrous architecture and achieving a superior recovery ration (78%) and rehydration ration (186.5%) compared to HAD, VFAD, and MWD. While the zeta potential remained statistically invariant across methods, HAD induced the largest particle agglomeration, followed by MWD. Notably, VFD enhanced protein stability, increasing the sulfhydryl content by 163.2% and reducing carbonyl formation by 48.1% relative to HAD, whereas MWD had the opposite effect. Multispectral analyses revealed the severe disruption of protein secondary and tertiary structures after MWD, while VFD minimized conformational denaturation. Statistical modeling ranked the drying sensitivity parameters as follows: surface hydrophobicity > hardness> β-turn content > dityrosine crosslinking > transverse relaxation time T23. These findings underscore VFD as the optimal method for mitigating structural degradation and oxidative damage in scallop processing, providing actionable insights to enhance the technofunctional quality of shelf-stable scallop products. Full article

Background: Wild boletes are famous for their exceptional flavor and nutritional value. Due to their susceptibility to decay and spoilage, dry storage is a common method for processing and preservation. However, few studies have reported on the alterations of metabolites of boletes resulting from different drying methods. This paper aims to investigate the metabolic changes in two species of boletes, Butyriboletus roseoflavus and Lanmaoa asiatica, subjected to three drying methods: hot-air drying, microwave drying, and freeze drying. Method and Result: Nuclear magnetic resonance (NMR) metabolomics was utilized for multivariate data analysis. In total, 27 metabolites were identified from the two species of boletes, including amino acids such as glutamate and leucine, sugars like glucose and sucrose, and alkaloids like choline. Among these, 17 metabolites were classified as differential metabolites, comprising 12 amino acids, 4 sugars, and 1 alkaloid. Differential metabolites were quantified by quantitative NMR (qNMR), and these metabolites were subsequently analyzed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database for pathway enrichment analysis. KEGG pathway analysis revealed that the different drying methods resulted in significantly distinct metabolic pathways for these differential metabolites, resulting in the enrichment of amino acid metabolism and starch and sucrose metabolism pathways. Conclusions: This metabolomics study elucidates the differences in metabolite composition and abundance between the two species of boletes, providing a theoretical foundation for selecting appropriate drying methods for their preservation. Full article

This study combined gas chromatography–ion mobility spectrometry (GC-IMS) and multivariate statistical analysis to explore the differences in the characteristic aroma of Idesia polycarpa Maxim (I. polycarpa) fruit and oil under different drying methods: natural drying (ND), hot air drying (HAD), microwave drying (MD), and microwave vacuum drying (MVD). The results revealed that 91 volatile compounds were identified in the fruit, and 82 were found in the oil of I. polycarpa. HAD and MD resulted in the most significant loss of volatile aroma in both the fruit and oil. In contrast, MVD demonstrated the best retention of these volatile aromas. Multivariate statistical analysis and odor activity value (OAV) analysis (OAV ≥ 1) were employed to identify 10 volatile aroma compounds considered differentiating factors in the fruit and oil subjected to different drying methods. These compounds, including hexanal, 3-methylbutyric acid, 2-acetylpyridine, guaiacol, valeraldehyde, and butyric acid, significantly contribute to the flavor characteristics of I. polycarpa fruit and oil, evoking notes of nuts, caramel, and sourness. The OAVs of these aroma-differentiating compounds in microwave vacuum-dried fruit and oil were higher compared to those from other drying methods. Therefore, when considering the enhancement of volatile flavor compounds, MVD is more effective than the other drying methods in promoting the formation of flavor compounds in I. polycarpa fruit and oil. Full article

The wild mushroom Cyttaria espinosae, also known as digüeñe, is a parasitic ascomycete of Nothofagus trees endemic to southern Chile. This species of wild mushroom is of great nutritional importance, especially for the Mapuche indigenous communities, and is highly sought after. Edible wild mushrooms, rich in bioactive compounds, are a potential source of health-promoting components. In the case of C. espinosae, research on its bioactive compounds is still lacking as is research, on the effect of preservation treatments on these compounds due to its perishability. This study evaluates the effects of three drying treatments; freeze-drying, hot-air drying, and microwave–vacuum drying. The rehydration capacity, color, and microstructural properties of dried mushrooms were evaluated using SEM, while, total phenolic content, antioxidant activity determined by DPPH and ORAC assays, and ergothioneine levels were investigated in both fresh and dried extracts of C. espinosae. The results showed that freeze-drying and microwave–vacuum drying are recommended treatments for the digüeñe mushroom due to superior outcomes in rehydration rate, color, and structural properties observed through SEM images. Total phenolic content and antioxidant activity were higher in mushroom extracts dried by microwave–vacuum compared to the other drying treatments. Full article

Edible mushrooms have been part of the human diet for centuries. Traditionally, they have been used for culinary and medicinal purposes due to their chemical composition and nutritional value, including their high antioxidant activity attributed to key metabolites such as phenolic compounds and ergothioneine. P. ostreatus mushrooms, known for their potent antioxidant activity, are prone to spoilage shortly after harvest, making preservation methods necessary. Various drying methods were evaluated to determine their effects on physicochemical characteristics, antioxidant properties, and ergothioneine content. Mushrooms were subjected to freeze-drying (FD), hot-air-drying (HAD), and microwave-vacuum-drying (MVD). The rehydration rate, color, and microstructural characteristics of extracts from fresh and dried P. ostreatus mushrooms were evaluated. Additionally, the total soluble phenolic content and antioxidant activity were assessed using DPPH and ORAC assays, along with the determination of ergothioneine content. FD and HAD at 40 °C showed the best results regarding the physicochemical characteristics. In terms of total soluble phenolic content, antioxidant activity, and ergothioneine content, the mushrooms dried using HAD at 40 °C showed the best retention of bioactive compounds. Among the evaluated methods, HAD at 40 °C proved to be a suitable alternative for processing P. ostreatus. Full article

The drying process is crucial for maintaining the quality of peanut pods and mitigating the risk of mold proliferation. The aim of this study was to investigate the kinetic characteristics of a synergistic intermittent microwave and a hot-air-drying technique, with an emphasis on enhancing efficiency and reducing energy consumption. A comprehensive analysis was performed on key parameters—including moisture content, moisture ratio, drying rate, and effective moisture diffusion coefficient—to elucidate moisture migration during the drying process. The findings indicated that higher microwave power significantly accelerates the drying rate while substantially shortening the drying time for peanut pods. The effective moisture diffusion coefficient was found to range from 0.987 × 10⁻⁹ to 1.227 × 10⁻⁹ m²/s, with the Verma model demonstrating superior accuracy in predicting drying behavior. The experiment achieved a minimum specific energy consumption of 12,535 kJ/kg and a maximum thermal efficiency of 18.1% at a microwave power density of 0.8 W/g combined with a temperature of 40 °C. However, the observed thermal efficiency was lower than that in previous studies, mainly due to the suboptimal regulation of experimental parameters. Future research should focus on optimizing these parameters and further exploring the impact of this drying method on energy consumption to achieve more efficient and sustainable peanut drying. Full article

Fruit and vegetable industrialisation is a major contributor to food waste; thus, its integral transformation into functional powders has gained attention. Pretreatments can be incorporated into valorisation processes to generate structural or biochemical changes that improve powders’ characteristics. This study deepens into the impact of biological (fermentation, FERM) and thermophysical (autoclaving, AUTO; microwaves, MW; ultrasound, US; and pasteurisation, PAST) pretreatments, combined with dehydration (hot air-drying, HAD; or freeze-drying, FD) on the characteristics of powdered products obtained from broccoli stems. The impact of pretreatments on physicochemical (moisture, water activity, total soluble solids) and antioxidant properties (phenols, flavonoids, antioxidant capacity by ABTS and DPPH) on residue and powdered products was studied, together with their impact on plant tissue structure (Cryo-SEM) and the powders’ phenolic profile (HPLC). Probiotic viability was also determined on the fermented samples. The pretreatments applied, particularly the ultrasound, improved the antioxidant properties of the broccoli stems compared to the unpretreated samples, in line with microscopic observations. Dehydration did also improve the antioxidant attributes of the broccoli wastes, especially drying at 60 °C. However, pretreatments combined with dehydration did not generally lead to an improvement in the antioxidant properties of the powders. Probiotic properties were preserved in the freeze-dried products (>10⁷ CFU/g). In conclusion, pretreatments may be applied to enhance the antioxidant attributes of broccoli wastes, but not necessarily that of dried powdered products. Full article

Ginseng (Panax ginseng C. A. Meyer) is a valuable plant resource which has been used for centuries as both food and traditional Chinese medicine. It is popular in health research and markets globally. Fresh ginseng has a high moisture content and is prone to mold and rot, reducing its nutritional value without proper preservation. Drying treatments are effective for maintaining the beneficial properties of ginseng post-harvest. In this study, we investigated the effects of natural air drying (ND), hot-air drying (HAD), vacuum drying (VD), microwave vacuum drying (MVD), and vacuum freeze drying (VFD) on volatile organic compounds (VOCs) in ginseng. The results showed that the MVD time was the shortest, followed by the VFD, VD, and HAD times, whereas the ND time was the longest, but the VFD is the most beneficial to the appearance and color retention of ginseng. A total of 72 VOCs were obtained and 68 VOCs were identified using the five drying methods based on gas chromatography–ion mobility spectrometry (GC-IMS) technology, including 23 aldehydes, 19 alkenes, 10 alcohols, 10 ketones, 4 esters, 1 furan, and 1 pyrazine, and the ND method was the best for retaining VOCs. GC-IMS fingerprints, principal component analysis (PCA), Euclidean distance analysis, partial least squares discriminant analysis (PLS-DA), and cluster analysis (CA) can distinguish ginseng from different drying methods. A total of 29 VOCs can be used as the main characteristic markers of different drying methods in ginseng. Overall, our findings provide scientific theoretical guidance for optimizing ginseng’s drying methods, aromatic health effects, and flavor quality research. Full article