Effect of drying methods on aroma, taste and antioxidant activity of Dendrobium officinale flower tea: A sensomic and metabolomic study.

Dendrobium officinale flower tea (DFT) is a traditional health product of geographical identity known for its unique aroma and taste. The effects of different drying methods on sensory properties, metabolic profiles and antioxidant activity of DFT were compared using sensomics and metabolomics approaches. Twenty-seven aroma-active compounds were identified and more than half of the volatiles responsible for the "green" and "floral" scent lost after drying. Sensory evaluations revealed that vacuum freeze-dried DFT showed a significant preference in taste and fifty-eight metabolites with higher levels of glutamine were observed, possibly contributing to a "fresh" taste and increased preference. Among the three drying methods, natural air drying retained the fresh flower scent better, while freeze drying preserved the color and shape of the flowers better and enhanced the taste and antioxidant activity of DFT. The research results may provide a foundation for the selection of DFT processing method and quality detection.

Optimization of Hypericum Perforatum Microencapsulation Process by Spray Drying Method.

Hypericum perforatum (HP) contains valuable and beneficial bioactive compounds that have been used to treat or prevent several illnesses. Encapsulation technology offers protection of the active compounds and facilitates to expose of the biologically active compounds in a controlled mechanism. Microcapsulation of the hydroalcoholic gum arabic and maltodextrin have hot been used as wall materials in the encapsulation of HP extract. Therefore, the optimum microencapsulation parameters of Hypericum perforatum (HP) hydroalcoholic extract were determined using response surface methodology (RSM) for the evaluation of HP extract. Three levels of three independent variables were screened using the one-way ANOVA. Five responses were monitored, including total phenolic content (TPC), 2,2-Diphenyl-1-picrylhydrazyl (DPPH), carr index (CI), hausner ratio (HR), and solubility. Optimum drying conditions for Hypericum perforatum microcapsules (HPMs) were determined: 180 °C for inlet air temperature, 1.04/1 for ratio of maltodextrin to gum arabic (w/w), and 1.98/1 for coating to core material ratio (w/w). TPC, antioxidant activity, CI, HR, and solubility values were specified as 316.531 (mg/g GAE), 81.912%, 6.074, 1.066, and 35.017%, respectively, under the optimized conditions. The major compounds of Hypericum perforatum (hypericin and pseudohypericin) extract were determined as 4.19 µg/g microcapsule and 15.09 µg/g microcapsule, respectively. Scanning electron microscope (SEM) analysis revealed that the mean particle diameter of the HPMs was 20.36 µm. Based on these results, microencapsulation of HPMs by spray drying is a viable technique which protects the bioactive compounds of HP leaves, facilitating its application in the pharmaceutical, cosmetic, and food industries.

Electrostatic spray drying: A new alternative for drying of complex coacervates.

Complex coacervation can be used for controlled delivery of bioactive compounds (i.e., flaxseed oil and quercetin). This study investigated the co-encapsulation of flaxseed oil and quercetin by complex coacervation using soluble pea protein (SPP) and gum arabic (GA) as shell materials, followed by innovative electrostatic spray drying (ES). The dried system was analyzed through encapsulation efficiency (EE) and yield (EY), morphological and physicochemical properties, and stability for 60 days. Small droplet size emulsions were produced by GA (in the first step of complex coacervation) due to its greater emulsifying activity than SPP. Oil EY and EE, moisture, and water activity in dried compositions ranged from 75.7 to 75.6, 76.0-73.4 %, 3.4-4.1 %, and 0.1-0.2, respectively. Spherical microcapsules were created with small and aggregated particle size but stable for 60 days. An amount of 8 % of quercetin remained in the dried coacervates after 60 days, with low hydroperoxide production. In summary, when GA is used as the emulsifier and SPP as the second biopolymer in the coacervation process, suitable coacervates for food applications are obtained, with ES being a novel alternative to obtain coacervates in powder, with improved stability for encapsulated compounds. As a result, this study helps provide a new delivery system option and sheds light on how the characteristics of biopolymers and the drying process affect coacervate formation.

Historical evolution and processing mechanism of 'nine steaming and nine drying' of traditional Chinese medicine preparation.

CONTEXT: Nine steaming and nine drying is a traditional Chinese medicine (TCM) processing method and it is widely used for processing tonifying herbs. Modern research reveals that the repeated steaming and drying process varies the composition and clinical efficacy of TCM. OBJECTIVE: This paper analyzes and explores the historical evolution, research progress, development strategies, and problems encountered in the nine steaming and nine drying process so as to provide a reasonable explanation for this method. METHODS: English and Chinese literature from 1986 to 2023 was collected from databases including Web of Science, PubMed, Elsevier, Chinese Pharmacopoeia 2020 (CP), and CNKI (Chinese). Nine steaming and nine drying, processing, TCM and pharmacological activity were used as the key words. RESULTS: Nine steaming and nine drying has undergone thousands of years of clinical practice. Under specific processing conditions of nine steaming and nine drying, the ingredients of the TCM have significant changes, which in turn altered clinical applications. CONCLUSIONS: This review provides sufficient evidence to prove the rationality and scientific value of nine steaming and nine drying and puts forward a development direction for future research.

Exploring conventional and emerging dehydration technologies for slurry/liquid food matrices and their impact on porosity of powders: A comprehensive review.

The contribution of dehydration to the growing market of food powders from slurry/liquid matrices is inevitable. To overcome the challenges posed by conventional drying technologies, several innovative approaches have emerged. However, industrial implementation is limited due to insufficient information on the best-suited drying technologies for targeted products. Therefore, this review aimed to compare various conventional and emerging dehydration technologies (such as active freeze, supercritical, agitated thin-film, and vortex chamber drying) based on their fundamental principles, potential applications, and limitations. Additionally, this article reviewed the effects of drying technologies on porosity, which greatly influence the solubility, rehydration, and stability of powder. The comparison between different drying technologies enables informed decision-making in selecting the appropriate one. It was found that active freeze drying is effective in producing free-flowing powders, unlike conventional freeze drying. Vortex chamber drying could be considered a viable alternative to spray drying, requiring a compact chamber than the large tower needed for spray drying. Freeze-dried, spray freeze-dried, and foam mat-dried powders exhibit higher porosity than spray-dried ones, whereas supercritical drying produces nano-porous interconnected powders. Notably, several factors like glass transition temperature, drying technologies, particle aggregation, agglomeration, and sintering impact powder porosity. However, some binders, such as maltodextrin, sucrose, and lactose, could be applied in controlled agglomeration to enhance powder porosity. Further investigation on the effect of emerging technologies on powder properties and their commercial feasibility is required to discover their potential in liquid drying. Moreover, utilizing clean-label drying ingredients like dietary fibers, derived from agricultural waste, presents promising opportunities.

Effectiveness of biological drying for citric acid dewatered sludge: Evaluating the impact of energy-efficient ventilation strategies.

The effectiveness of dehydration and utilization processes for citric acid dewatered sludge is hampered by its high concentrations of polysaccharides, proteins, and water-binding properties of microbial extracellular polymers (EPS). This research explores the efficacy and mechanisms involved in extracting water from this type of sludge using biological drying technology, with varying rates of ventilation. Especially pertinent was the use of low ventilation rates as control variables. Our results suggest that a scheduled intermittent ventilation at lower rates allows for the most efficient removal of water, achieving a rate of 41.71 % within eight days, according to the zero-order kinetic model. Remarkably, the peak temperature registered was 60 °C, reaching this threshold in just 0.1 days and maintaining high temperatures for approximately 5.9 days. Component analysis of organic matter illustrated a preferential degradation process for lipids under these ventilation conditions which is pivotal for releasing and transforming bound water for efficient extraction, as well as facilitating the breakdown of easily hydrolysable materials. Further, polysaccharide/protein (EPS) decomposition contributed to water removal, though less significantly. The periodic ventilation strategy allowed for the maximum cumulative temperature to be sustained, demonstrating superior efficiency in harnessing bio-generated heat (82.77 % for water evaporation), resulting in dry sludge suitable for self-sustained combustion at relatively low cost ($26.61/t). Highlighted by this study is the considerable potential of energy-efficient ventilation methods in the biological drying treatment of citric acid fermented sludge and similar industrial waste materials.

Spray-drying of PEI-/PPI-based nanoparticles for DNA or siRNA delivery.

Spray-drying of nucleic acid-based drugs designed for gene therapy or gene knockdown is associated with many advantages including storage stability and handling as well as the possibility of pulmonary application. The encapsulation of nucleic acids in nanoparticles prior to spray-drying is one strategy for obtaining efficient formulations. This, however, strongly relies on the definition of optimal nanoparticles, excipients and spray-drying conditions. Among polymeric nanoparticles, polyethylenimine (PEI)-based complexes with or without chemical modifications have been described previously as very efficient for gene or oligonucleotide delivery. The tyrosine-modification of linear or branched low molecular weight PEIs, or of polypropylenimine (PPI) dendrimers, has led to high complex stability, improved cell uptake and transfection efficacy as well as high biocompatibility. In this study, we identify optimal spray-drying conditions for PEI-based nanoparticles containing large plasmid DNA or small siRNAs, and further explore the spray-drying of nanoparticles containing chemically modified polymers. Poly(vinyl alcohol) (PVA), but not trehalose or lactose, is particularly well-suited as excipient, retaining or even enhancing transfection efficacies compared to fresh complexes. A big mesh size is critically important as well, while the variation of the spray-drying temperature plays a minor role. Upon spray-drying, microparticles in a âˆ¼ 3.3 - 8.5 µm size range (laser granulometry) are obtained, dependent on the polymers. Upon their release from the spray-dried material, the nanoparticles show increased sizes and markedly altered zeta potentials as compared to their fresh counterparts. This may contribute to their high efficacy that is seen also after prolonged storage of the spray-dried material. We conclude that these spray-dried systems offer a great potential for the preparation of nucleic acid drug storage forms with facile reconstitution, as well as for their direct pulmonary application as dry powder.

[Application of microwave vacuum drying with process management in extract drying of personalized traditional Chinese medicine preparations].

Extracts are important intermediates in the production of traditional Chinese medicines preparations. The drying effect of extracts will directly affect the subsequent production process and the quality of the preparation. To meet the requirements of high drug loading, short time consumption, and simple production process of personalized traditional Chinese medicine preparations, this study explored the application of multi-program microwave vacuum drying process in the extract drying of personalized traditional Chinese medicine preparations. The influencing factors of microwave vacuum drying process were investigated for 5 excipients and 40 prescriptions. Taking the feasibility of drying, drying rate, drying time, and dried extract status as indicators, this study investigated the feeding requirements of microwave vacuum drying. With the dried extract status as the evaluation indicator, the three drying programs(A, B, and C) were compared to obtain the optimal drying condition. The experimental results showed that the optimal feeding conditions for microwave vacuum drying were material layer thickness of 2 cm and C program(a total of 7 drying processes), which solved the problem of easy scorching in microwave drying with process management. Furthermore, the preset moisture content of the dried extract in microwave drying should be 4%-5%, so that the dried extract of traditional Chinese medicine preparation had uniform quality, complete drying, and no scorching. This study lays a foundation for the application of microwave drying in the production of traditional Chinese medicine preparations, promoting the high-quality development of personalized traditional Chinese medicine preparations.

Monitoring vegetable dehydration process by aquaphotomics from lab scale to farm.

Solar dehydration processes, implemented with NIR sensors, were studied. The research plan was divided into phases to achieve specific objectives. Phase 1: laboratory tests on micro plants; phase 2: scale transposition tests on small-sized plants - pilot scale; phase 3: tests on commercial systems already in use by Italian SMEs. The realisation of the scheduled activities started with the design, programming, and positioning of NIR sensor for data collection and configuration optimization. NIR spectra were collected in reflectance mode (900-1700 nm) using the MicroNIR1700™ or the MicroNIR On-site W™ (VIAVI Solutions Italia S.r.L., Monza, Italy) portable spectrometers with the MicroNIR Pro ES 1700 software. Spectra were acquired automatically throughout the process by placing the NIR probe over a sample slice, positioned on the intermediate shelf. The probe was thermally insulated to avoid temperature variations. The spectra were first transformed by converting reflectance to absorbance; then the second derivative Savitzky-Golay filter (second order polynomial fit and 21 points) and multiplicative scatter correction were applied to remove potential scatter effects. Aquagrams were calculated from the spectral data. The experiments were carried out with a micro-drying system (45x45x45 cm), and a pilot scale plant available at CREA.IT (Milan). Then, the transfer of the selected configuration was realised using a commercial plant already active in a farm of Pavia area. Different food matrices were tested (pineapple, apple, melon, eggplant, onion). NIR data processing by multivariate analysis was made to prove the reliability of the aquaphotomics approach in detecting the actual end of the drying process. The evaluation of the potential development of dedicated App, easy to consult, to be made available through integration on virtual platform was finally computed.

Effect of the Drying Method and Storage Conditions on the Quality and Content of Selected Bioactive Compounds of Green Legume Vegetables.

This study aimed to determine the effect of the drying method (freeze-drying, air-drying), storage period (12 months), and storage conditions (2-4 °C, 18-22 °C) applied to two legume species: green beans and green peas. The raw and dried materials were determined for selected physical parameters typical of dried vegetables, contents of bioactive components (vitamin C and E, total chlorophyll, total carotenoids, ß-carotene, and total polyphenols), antioxidative activity against the DPPH radical, and sensory attributes (overall quality and profiles of color, texture, and palatability). Green beans had a significantly higher content of bioactive components compared to peas. Freeze-drying and cold storage conditions facilitated better retention of these compounds, i.e., by 9-39% and 3-11%, respectively. After 12 months of storage, higher retention of bioactive components, except for total chlorophyll, was determined in peas regardless of the drying method, i.e., by 38-75% in the freeze-dried product and 30-77% in the air-dried product, compared to the raw material.

Effects of Drying Methods on the Antioxidant Properties of Piper betle Leaves.

Piper betle leaf powder is increasingly utilised as a health supplement. In this study, P. betle leaves were subjected to four different drying methods: convective air-drying, oven-drying, sun-drying, and no drying, with fresh leaves as control. Their antioxidant properties were then evaluated using colourimetric assays and GC-MS. Results showed that the sun-dried leaves had the highest (p < 0.05) total antioxidant capacity (66.23 ± 0.10 mg AAE/g), total polyphenol content (133.93 ± 3.76 mg GAE/g), total flavonoid content (81.25 ± 3.26 mg CE/g) and DPPH radical scavenging activity (56.48 ± 0.11%), and the lowest alkaloid content (45.684 ± 0.265 mg/gm). GC-MS analysis revealed that major constituents of aqueous extracts of fresh and sun-dried P. betle leaves were hydrazine 1,2-dimethyl-; ethyl aminomethylformimidate; glycerin; propanoic acid, 2-hydroxy-, methyl ester, (+/-)-; and 1,2-Cyclopentanedione. In conclusion, sun-dried leaves exhibited overall better antioxidant properties, and their aqueous extracts contained biologically active phytoconstituents that have uses in various fields.

Evaluation of aroma characteristics of Penaeus vannamei with different drying methods using HS-SPME-GC-MS, MMSE-GC-MS, and sensory evaluation.

The effects of microwave drying (MD), hot air drying (HAD), vacuum hot air drying (VD), and vacuum freeze drying (VFD) on the volatile profiles of Penaeus vannamei were investigated. A total of 89 and 94 volatile compounds were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and monolithic material sorptive extraction gas chromatography-mass spectrometry (MMSE-GC-MS), respectively. Orthogonal partial least squares-discriminant analysis (OPLS-DA) and variable influence on projection (VIP) models were utilized to select characteristic volatiles and key marker compounds (e.g., octanal, 1-octen-3-ol, 2-methyl-butanal, 2-ethyl-furan, and trimethyl-pyrazine) to discriminate among four drying methods. Based on synthesis of odor descriptions and sensory evaluation, it was found that P. vannamei via MD, HAD, and VD greatly reduced the fishy and generated roasted, fatty, and smoked odors. This study systematically analyzed the aroma characteristics of four traditional dried P. vannamei products, which may provide theoretical guidance for industrial production.

Hot air-assisted radio frequency drying of corn kernels: the effect on structure and functionality properties of corn starch.

Hot air (HA) drying caused quality damage of grains with long treatment time. Radio frequency (RF) heating as an emerging technology was applied to improve drying quality of cereals effectively. The effects of HA-RF drying (50 °C, 70 °C, 90 °C) of corn kernels on the morphology, structure, and physicochemical properties of starch were investigated and compared with HA drying. The surface of treated starch became rough, along with fragments and pores. Drying treatments increased the amylose content from 10.59 % to 23.88 % and the residual protein content of starch from 0.58 % to 1.23 %, and reduced the crystallinity from 31.95 % to 17.15 % and short-range order structures of starch from 0.918 to 0.868. The change of structures in turn resulted in the increase of pasting viscosity, gelatinization temperature, storage modulus and loss modulus. Furthermore, the HA-RF dried starch displayed stronger thermal stability, higher gelatinization degree and better gelation properties than the HA-treated starch at the same temperature. The data proved that the synergistic effects of HA and RF were more effective in modulating the starch structure and improving the functional characteristics of corn starch. This paper would like to provide potential reference for better application of HA-RF technologies to corn.

Physicochemical and sensorial properties of tomato leathers at different drying conditions.

Tomato leather as a healthy alternative to traditional fruit leathers was formulated. A tray dryer with changing temperature (50, 60, and 70°C) and relative humidity (5%, 10%, and 20%) was used to achieve the best product in terms of color, water distribution, lycopene content, mechanical, and sensorial properties. Color change was the highest at 70°C due to the Maillard reaction. Lycopene content was also the highest at 70°C. Time domain-NMR relaxometry showed that water distribution of all samples was homogeneous and similar to each other. Processing conditions affected mechanical properties significantly. The highest tensile strength was observed at 70°C, possibly due to the denatured proteins. Sensory analysis indicated better flavor development at 70°C, whereas overall acceptability of samples was higher at 50°C. The results of this study showed the main processing parameters of tomato leather with a minimal amount of ingredients, with acceptable mechanical and sensorial properties. PRACTICAL APPLICATION: Tomato leather was produced by using minimal amount of ingredients. Taste of the leather was found acceptable, as a salty snack food. Therefore, this product can be produced economically and it has a high potential to be consumed as an alternative to conventional fruit leathers.

A study into how thickness, infrared intensity, and airflow affect drying kinetics, modeling, activation energy, and quality attributes of apple slices using infrared dryer.

Drying is a widely recognized process that reduces the need for storage and shipping weight, keeps free water out of the product, and prolongs its shelf life. An infrared dryer was designed to dry apples under different drying conditions. Apple slices of 6-, 4-, and 2-mm thicknesses were dried at intensities 0.130, 0.225, and 0.341 W/cm2 and airflow 1.0, 0.5, and 1.5 m/s. The dehydrating period was prolonged with higher airflow and shortened with higher infrared intensity (IR). The shortest dehydrating period was verified by 190 min at 0.341 W/cm2, 0.5 m/s under 2 mm thickness. Increasing the sample thickness from 2 to 4 mm and then to 6 mm resulted in an 84% and 192% increase in drying time, respectively. Dehydrated apples had water activity values ranging from 0.30 to 0.40. The shrinkage ratio increased with an increase in infrared radiation intensity. However, it decreased with an increase in air velocity, while the rehydration ratio decreased with an increase in radiation intensity and increased with an increase in air velocity. Regarding total color change, apple slice thickness was a major factor. The effective diffusivities varied between 2.6 and 9.0 𝗑10-10 m2/s under different drying conditions. The dehydrating curves of apples were best described by the model developed by Midilli et al.

How spray drying processing and solution composition can affect the mAbs stability in reconstituted solutions for subcutaneous injections. Part I: Contribution of processing stresses against composition.

Spray drying is increasingly being applied to process biopharmaceuticals, particularly monoclonal antibodies (mAbs). However, due to their protein nature, mAbs are susceptible to degradation when subjected to various stresses during a drying process. Despite extensive research in this domain, identifying the appropriate formulation composition and spray drying conditions remains a complex challenge, requiring further studies to enhance the understanding on how process and formulation parameters impact mAb stability in reconstituted solutions. This research aims to explore spray drying as technique for producing pharmaceutical mAbs-based powders intended for reconstitution and subcutaneous injection. In the initial phase of this study, using a model mAb (mAb-A), the influence of dissociated and coupled process stresses on protein stability after solution reconstitution was investigated. The findings revealed a detrimental interplay of mechanical, interfacial, and thermal/dehydration stresses on mAb-A stability, notably characterized by an increase in protein aggregation. Subsequently, in a second phase, the study delved into the impact of spray drying processing conditions, the level of excipients, and protein concentration on mAb-A aggregation in reconstituted solutions. The obtained results highlighted the critical role of formulation composition as a parameter deserving further study, specifically concerning the selection of type and concentration of stabilizers to be added in the liquid mAb-A solution to be dried.

Impact of different hand-drying methods on surrounding environment: aerosolization of virus and bacteria, and transfer to surfaces.

BACKGROUND: In recent years, hand drying has been highlighted as a key step in appropriate hand hygiene, as moisture on hands can increase the transfer of micro-organisms from hands to surfaces and vice versa. AIM: To understand bacterial and viral aerosolization following hand drying, and study the transfer of micro-organisms from hands to surfaces after drying using different methods. METHODS: Groups of five volunteers had their hands pre-washed with soap, rinsed and dried, then inoculated with a concentrated mixture of Pseudomonas fluorescens and MS2 bacteriophage. Volunteers entered an empty washroom, one at a time, and rinsed their hands with water or washed their hands with soap prior to drying with a jet dryer or paper towels. Each volunteer applied one hand successively to various surfaces, while their other hand was sampled using the glove juice method. Both residual bacteria and viruses were quantified from the washroom air, surface swabs and hand samples. FINDINGS: P. fluorescens and MS2 bacteriophages were rarely aerosolized while drying hands for any of the drying methods studied. Results also showed limited, and similar, transfer of both micro-organisms studied on to surfaces for all drying methods. CONCLUSION: The use of jet dryers or paper towels produces low levels of aerosolization when drying hands in a washroom. Similarly, all drying methods result in low transfer to surfaces. While the coronavirus disease 2019 pandemic raised concerns regarding public washrooms, this study shows that all methods tested are hygienic solutions for dry washed hands.

Comparative evaluation of drying methods for struvite produced from electrocoagulated source-separated urine: Implications for quality, energy and cost-effectiveness.

Struvite precipitation from source-separated urine is crucial for waste utilization and sustainability. However, after precipitation, the high moisture content of struvite necessitates an additional drying process that can be costly and inefficient. In the present study, the performance of different drying methods-open sun drying, air drying, conventional drying (20-100 °C), and microwave drying (180-720 W) on the quality of struvite obtained from source-separated urine through electrocoagulation using Mg-Mg electrodes were evaluated. It was found that higher temperatures and power in the convective oven and microwave resulted in higher diffusivity (10-9-10-7 m2s-1), leading to reduced drying times. Different models were employed to comprehend the drying mechanism, and the one with the highest correlation coefficient (R2 = 0.99) and the lowest statistical values was selected. The key findings indicated that higher power and temperature levels were more cost-effective. However, characterization of the dried struvite using X-ray diffraction and Fourier-transformed infrared spectroscopy, disintegration of struvite crystals at temperatures above 60 °C in the conventional oven and 180 W in the microwave oven was observed. Based on the results, we conclude that sun drying is a cost-effective and environmentally friendly alternative for drying struvite without compromising its quality.

Improvement of the drying quality of blueberries by catalytic infrared blanching combined with ultrasound pretreatment.

This paper investigated the effect of catalytic infrared blanching combined with ultrasound pretreatment on quality and waxy structure of blueberries. Different blueberry samples were prepared, including control (untreated) and samples treated by hot water blanching (HB), catalytic infrared blanching (CIB), ultrasound-catalytic infrared blanching (US-CIB), and catalytic infrared blanching-ultrasound (CIB-US). The effect of different pretreatments on the microstructure of blueberry epidermis was studied. The drying time of blueberries after HB, US-CIB, and CIB-US was decreased by 11.61%, 17.54%, and 17.27%, respectively, compared with control (33.75 h), and drying efficiency was significantly improved. Blueberries after pretreatments had higher content of polyphenol and anthocyanin, with an increase of 29.51-44.21% in phenol and 8.81-20.80% in anthocyanin, the antioxidant capacity of blueberries was also better than control and CIB enhanced the antioxidant capacity of blueberries. CIB-US can be used as an efficient pretreatment method for blueberry drying.

Sensory properties of rehydrated Toona sinensis shoots after dehydrated by different drying methods and association with gamma-glutamyl transferase reaction.

Sulfur-containing compounds are responsible for the aroma of Toona sinensis shoot (TS). In this study, vacuum-freeze-drying (VFD), microwave-drying (MD), and hot-air-drying at 100 and 40 °C (HAD100 and HAD40, respectively), were applied to dehydrate perishable TS for preservation. VFD-TS retained most aroma of fresh/raw TS after rehydration. The content of sulfur-containing compounds reached to 118.00 µg/g with leading by methyl thiirane, (E,E)/(E,Z)/(Z,Z)-bis-(1-propenyl) disulfides, and (Z)/(E)-2-mercapto-3,4-dimethyl-2,3-dihydrothiophenes accounting for 86.33 %. They were undetected in the rehydrated MD-TS and HAD100-TS, as the indigenous enzymes in TS were deactivated under their dehydration conditions. Interestingly, the sulfur-containing compounds was restored by 77.47 % after the TS was treated by gamma-glutamyl transferase (GGT). Thus, the release of sulfur-containing compounds from TS could depend on GGT reaction. It was different from alliaceous vegetables relying on alliinase reaction. The results revealed the aroma formation in TS and provided an approach to enhance the aroma of TS dried by different methods.