Microwave vacuum combined drying of Macrobrachium rosenbergii meat: Effects of moisture transition points on drying kinetics, microstructure, quality, and flavor characteristics

In recent years, there has been an increasing demand for high-quality dried aquatic products that possess similar organoleptic and nutritional qualities to their fresh counterparts. The present study investigated the effects of hot air drying (HAD), heat pump drying (HPD), vacuum freeze drying (VFD) and microwave vacuum drying (MVD) on drying efficiency, physicochemical and microstructural properties, and volatile compounds of Macrobrachium rosenbergii meat. MVD achieved the highest drying efficiency, whereas VFD resulted in the highest levels of crude protein and astaxanthin contents. VFD also produced higher lightness but lower hardness compared to the other methods. Low-field nuclear magnetic resonance analysis revealed a leftward shift in the transverse relaxation time values of both free and immobilized water as the drying process continued. Scanning electron microscope analysis revealed dense structures with noticeable muscle fiber contractions for HAD and HPD samples, whereas numerous small voids generated for the VFD sample, but larger pores formed for the MVD sample. Fourier transform infrared spectroscopy indicated that VFD better maintained protein structural intergiry. Gas chromatography-mass spectrometry analysis revealed significant differences in volatile compounds, with the key flavors such as 1-octen-3-ol, decyl aldehyde and 1-nonanal present in all samples. Pyrazine compounds contributed roasted and nutty aromas to the HAD, HPD and MVD samples. Overall, MVD is a promising method for dehydration of M. rosenbergii meat. © 2026 Society of Chemical Industry.

Hot air drying (HAD) is the most commonly used method for citrus peel drying. However, the long time and low efficiency of this process leads to the degradation of product quality and a reduction in antioxidant activity. Therefore, in this study, to improve the drying efficiency and increase the product quality of dried citrus peel, the effects of microwave vacuum drying (MVD) were compared with HAD and vacuum freeze drying (VFD) with respect to their drying kinetics, bioactive compound profile and antioxidant capacity. The results showed that the drying rate decreased with increasing sample load but increased with increasing microwave power. The Page model was the best model for fitting the drying curve of citrus peel during MVD, and the highest rehydration rate (84.5%) was obtained at a microwave vacuum power of 600 W. The microstructure of citrus peel dried by MVD was assessed by scanning electron microscopy, and a loose structure with highly porous material was observed, whereas citrus peel dried by HAD was compact. The total phenolic content (10.48 ± 0.21 mg GAE/g DW), total flavonoid content (6.54 ± 0.41 mg RE/g DW) and oxygen radical absorbance capacity (279.29 ± 11.37 µmol TE/g DW) values obtained for citrus peel dried via MVD were significantly higher than those obtained using HAD (p < 0.05). Several phenolic acid substances and flavonoid profiles were identified and quantified by HPLC-DAD, including coumaric acid, nobiletin, and tangeretin. The nobiletin content observed after MVD was significantly higher than that measured after HAD and VFD. The overall results of this study revealed that MVD at lower microwave powers appears to be a good alternative to the conventional HAD of citrus peel.

A randomized block design experiment was performed to investigate the influence of drying on the physical, chemical and nutritional quality attributes of five prominent cultivars of India under sun drying (SD) (mean temperature 35.5 °C, average daily radiation 5.26 kW h m-2 and mean relative humidity 73.66% RH), hot air drying (HD) at 65 °C, microwave vacuum drying (MVD) (800 W, 5 kPa) and freeze drying (FD) (-50 °C, 5 kPa). Water activity, pH, total phenolic content (TPC), ascorbic acid (AA), capsaicin, β-carotene, color and Scoville heat unit were studied. TPC, AA, capsaicin content, β-carotene, color and water activity were significantly affected by the drying method. FD was observed to be most efficient in minimizing the loss of color, capsaicin and β-carotene. The hotness of analyzed samples decreased in the order 'Bird's Eye' > 'Sannam S4' > 'CO-4' > 'PLR-1' > 'PKM-1' among the studied cultivars, and FD > MVD > HD > SD among the drying methods. The FD method was observed to be the most efficient drying method for retaining capsaicin content over other drying methods (SD, HD, MVD), whereas MVD was found to be most efficient in minimizing the loss to nutritional attributes for all five pepper cultivars. © 2018 Society of Chemical Industry.

The aim of this study is to investigate efficient, cost‐effective, and high‐quality drying technologies for Rosa roxburghii Tratt. Five drying methods—hot air drying (HAD), microwave drying (MD), vacuum drying (VD), microwave vacuum drying (MVD), and freeze vacuum drying (FVD), were employed to dry Rosa roxburghii Tratt. The study focused on evaluating drying characteristics, colors, texture and structure, and microstructure, as well as the content of active ingredients and antioxidant activity of Rosa roxburghii Tratt. The results of drying kinetics indicated that the Wang and Singh model was the most suitable for FVD, while the Page model was optimal for the other four drying methods. Rosa roxburghii Tratt subjected to HAD exhibited the highest energy consumption per unit but the lowest ΔE and the highest TFC. The microstructure of Rosa roxburghii Tratt under different drying methods was analyzed. Rosa roxburghii Tratt dried using MD experienced serious cell rupture, resulting in a large loss of active ingredients and the worst antioxidant ability, but it had the fastest drying rate. On the other hand, Rosa roxburghii Tratt dried under VD had the microstructure with the least pore space, leading to slower drying speed and the highest total polyphenol content. Rosa roxburghii Tratt dried using MVD had the least hardness and chewiness, with slightly better ΔE and active ingredient content compared to MD. FVD Rosa roxburghii Tratt took the longest time to dry, with the greatest ΔE difference, hardness, and chewiness, but it had the highest Vitamin C content and the most powerful antioxidant ability. Principal component analysis (PCA)–entropy weighting method was used to provide comprehensive scores for the different drying methods, with FVD, HAD, VD, MVD, and MD were 0.8107, 0.7037, 0.4499, 0.2746, and 0.0586 respectively. Through comprehensive analysis, we demonstrated that the quality of Rosa roxburghii Tratt obtained via FVD and HAD is satisfactory. Additionally, HAD is characterized by its economic efficiency and convenience, providing valuable insights for the industrial production of Rosa roxburghii Tratt drying.

This study investigated the effects of drying methods (hot air drying (HAD), microwave vacuum drying (MVD), and vacuum freeze drying (VFD)) on the rehydration performance (RP) of dried Lanzhou lily scales (LLS). Rehydration rate and water migration showed that MVD had the best RP, followed by VFD, while HAD had the worst. The results of additional morphology observation using scanning electron microscopy (SEM) and micro X-ray computed tomography (CT) imaging showed that both MVD and VFD created more channels in more porous structures, which facilitated their better RP than that by HAD. The results also revealed the spatial structure diversity (including pores, channels size, and internal network) of each dried Lanzhou lily scale group. In addition, studies analyzed how drying techniques affected the physiochemical properties of lily starch, including its water solubility, pasting profiles, and starch particle morphology. The findings indicated that when MVD was in operation, partial gelatinization in lily starch was brought about by thermal effects, allowing MVDS crystals to change from B-type to V-type and causing MVDS to have better water absorption ability. Consequently, despite the fact that MVD’s desiccated lilies have a lower porous structure and thinner channels than VFD’s, MVD has a higher RP than VFD.

Drying methods impact bioactive compounds in Siraitia grosvenorii fruit: Metabolomic insights.

In order to improve the drying quality and obtain a crispy texture of papaya slices, microwave vacuum drying (MVD) was studied in this research. The effects of different slice thickness (3, 6, 9, 12 mm), microwave power density (6, 8, 10, 12 W/g), drying temperature (50, 55, 60, 65, 70°C), and vacuum degree in relative pressure (−75, −80, −85, −90 kPa) on the drying characteristics and comprehensive quality of papaya slice were discussed. The Box–Behnken central combination experiments were designed and the response surface optimization analysis was carried out. According to the results of the response surface experiments, the impact factors during papaya slices drying on the comprehensive score were ranked from largest to smallest as follows: microwave power density, vacuum degree, and drying temperature. The fragility and hardness of papaya slices showed an upward trend with the increase of thickness. The optimum technologic parameters were set at the microwave power density of 10 W/g, vacuum degree of −90 kPa, drying temperature of 54.58°C, and slice thickness of 6 mm. The comprehensive score F can be up to the maximum value of 8.80 with the deviation from the verification test of 4.4%, and the papaya slices with obvious pore structure and remarkable crispness were obtained. Novelty impact statement Microwave vacuum drying technology combines the advantages of microwave drying and vacuum drying, which has remarkable drying efficiency through internal heating and promotes the slices to form a crispy texture. In this work, the influence of different factors on the fragility and hardness quality of papaya chips were explored firstly. Increasing drying temperature has no significant influence on the fragility and hardness value. Meanwhile, the hardness value went up while the fragility fluctuated slightly as the power density was added. The variation trend of papaya porosity microstructure gradually expanded with the increase of vacuum degree. The results provided theoretical support for the application of microwave vacuum drying technology in papaya crisp chips.

This work aimed to investigate the effect of five drying methods, namely hot-air drying (HD), microwave drying (MD), vacuum drying (VD), vacuum microwave drying (VMD), and vacuum freeze-drying (VFD), on the bioactive compounds, antioxidant activity, color, sensory attributes, and microstructure of purple cabbage. Different drying methods considerably affected the quality factors of the products. The highest remaining total phenolic content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC) concentrations were observed in the VFD cabbage at 10.57 mg GAE/g, 7.01 mg RE/g, 6.54 C-3-G mg eqiv/g, respectively. This was followed by the VMD samples at a TPC at 9.06 GAE mg/g, TFC level of 5.84 mg RE/g, and TAC at 3.80 C 3 – G mg eqiv/g. Furthermore, the VFD samples displayed the best performance in antioxidant activity. The antioxidant activity of the VMD samples was lower than the VD and MD samples, but higher than the HD samples. In terms of color and flavor, the VMD samples displayed a low ∆E (P < .05) value, while the flavor resembled that of fresh purple cabbage, compared to the VFD sample. According to these chemical and physical indicators and drying time. VMD is better for drying treatment of purple cabbage.

This study evaluated the effects of microwave vacuum drying (MVD), microwave drying (MD), heat pump drying (HPD), hot air drying (HAD), and freeze drying (FD) on the drying kinetics, and changes of physicochemical properties and bioactive compound of Orah slices. In the analysis of the seven models examined, the Page model was found to be the most accurate in describing the changes in moisture content during the drying process. MD was significantly faster than HAD and HPD, reducing drying time by 95.12 and 94.17%, respectively, and increasing the effective moisture diffusion rate by 94.40%. Microscopic analysis showed MVD samples had large, uniform pores, which improved moisture diffusion. FD and MVD preserved bioactive nutrients and demonstrated superior antioxidant activity over other methods. MVD produced products with balanced texture, minimal color change, and the shortest drying time of 38min. MVD can be a promising dehydration technique for producing high-quality Orah products.

This study experimented on microwave-vacuum (MWV) drying of kiwifruit (Actinidia deliciosa) slices as a way to improve drying productivity and the quality of dried fruit. The effects of microwave power density, sample thickness and vacuum degree on the drying characteristics of kiwifruit slices were studied. The results showed that these three factors had significant effects on the vitamin C and chlorophyll contents and on the rehydration capacity of dried kiwifruit slices, as well as the total drying time. The processing parameters of MWV drying of kiwifruit slices were optimized by using Box–Behnken design with a quadratic regression model built by response surface methodology. The optimum processing parameters were experimentally determined as microwave power density at 7.7 W, sample thickness of 6.0 mm and MWV drying for 11.5 min at a vacuum degree of −90 kPa. High-quality dried kiwifruit slices can be created under these conditions using this drying process. Practical Applications Kiwifruit (Actinidia deliciosa) has become a popular fruit because of its bright green flesh, high level of vitamin C and because it contains a wide variety of phytonutrients, including carotenoids, lutein, phenolics, flavonoids and chlorophyll. It needs some form of preservation to extend its shelf life. Microwave-vacuum (MWV) drying is a novel alternative that combines the advantages of both microwave drying and vacuum drying. The objectives of this study were to investigate the effect of microwave power density, sample thickness and vacuum degree on the MWV drying characteristics and quality of MWV-dried kiwifruit slices, and to evaluate a suitable drying model for describing the drying process. In addition, the process parameters of MWV drying were optimized by response surface methodology. This present study provides the theoretical basis for industrial-scale production.

Comparison of different drying technologies for kiwifruit pomace: Changes in physical characteristics, nutritional properties and antioxidant capacities

Durian chips drying using combined microwave techniques with step-down microwave power input

The objective of the study was to whether the microwave vacuum drying system, which makes positive contributions to the quality characteristics in food drying, would have positive effects on the existing quality criteria by using explosion puffing drying after microwave vacuum drying and microwave vacuum drying after hot air drying. In this study, apple slices were dried in four single drying; air drying (AD) (70 °C, 2 m/s), microwave vacuum drying (MWVD) (1.5, 3 and 4.5 W/g) and six combined drying; the first 3 of 6 combined drying; AD (70 °C, 2 m/s) + MWVD (1.5, 3 and 4.5 W/g), the second 3 of 6 combined drying; MWVD (1.5, 3 and 4.5 W/g) + Explosion puffing drying (EPD) (0.6 MPa, 70 °C). It was determined that the apparent volumes of MWVD samples (1.5, 3 and 4.5 W/g) were 9, 17, and 51% higher than AD samples, respectively. With the MWVD and EPD processes applied after AD, a product structure with expanded and increased porosity was obtained, which increased the rehydration rate of the dried product. This was confirmed by the image analysis method, and the geometric structure, dimensions, and depth map of the porous material were examined using the MATLAB program for SEM images of dried products. We believe that a verification approach that is not available in the literature will contribute to the literature by providing an innovative approach for validation purposes in the evaluation of SEM images in drying studies. The total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2.2’ azinobis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) contents were higher in the MWVD samples than in the MWVD + EPD samples. TPC and antioxidant capacity were higher 2–1.87 times and 1.98–1.74 times for 4.5 W/g MWVD and 4.5 W/g MWVD + EPD dried apple as compared to air-dried apple slice. With the increase in power density per product in MWVD, the porosity, rehydration, total phenolic, DPPH and ABTS values of the product increased The MWVD and EPD methods prevent shrinkage and volume loss of the dried products, and a low bulk density product was obtained. Therefore, we can conclude that both puff drying and microwave -vacuum drying are successful methods for the production of dried apple slices.

The effects of drying on the quality, antioxidant activity and anthocyanin components of blueberry pomace were investigated using hot air drying (HAD), freeze-drying (FD), microwave vacuum drying (MVD) and microwave freeze vacuum drying (MFD). The quality, antioxidant activity, and individual anthocyanin compositions of blueberry pomace were evaluated and compared with the non-dried control. MVD produced the highest levels of total phenols, total anthocyanins, total sugars and color values in blueberry pomace while HAD gave the lowest. The ABTS +and DPPH radical scavenging abilities of blueberry pomace were significantly high when MVD was used. Moreover, FD, MVD, and MFD resulted in the retention of significantly more anthocyanin species than HAD as determined by HPLC coupled to the mass spectrometer. Overall, MVD proved to be the best technique for preservation of antioxidant capacity and natural color. Therefore, MVD of blueberry pomace can improve efficiency and productivity of the blueberry fruit processing industry while reducing the environmental burden.Graphical

Characterization of microwave vacuum drying and hot air drying of mint leaves ( Mentha cordifolia Opiz ex Fresen)