Light-Assisted Drying for the Thermal Stabilization of Nucleic Acid Nanoparticles and Other Biologics.

Cold-chain storage can be challenging and expensive for the transportation and storage of biologics, especially in low-resource settings. Nucleic acid nanoparticles (NANPs) are an example of new biological products that require refrigerated storage. Light-assisted drying (LAD) is a new processing technique to prepare biologics for anhydrous storage in a trehalose amorphous solid matrix at ambient temperatures. Small volume samples (10 µL) containing NANPs are irradiated with a 1064 nm laser to speed the evaporation of water and create an amorphous trehalose preservation matrix. In previous studies, samples were stored for 1 month at 4 °C or 20 °C without degradation. A FLIR SC655 mid-IR camera is used to record the temperature of samples during processing. The trehalose matrix was characterized using polarized light imaging to determine if crystallization occurred during processing or storage. Damage to LAD-processed NANPs was assessed after processing and storage using gel electrophoresis.

Role of thermal and non-thermal drying techniques on drying kinetics and the physicochemical properties of shiitake mushroom.

BACKGROUND: Fresh shiitake mushrooms are rich in nutrients, but have high water content, a fast metabolism after harvest, and deteriorate extremely easily. Therefore, the drying of shiitake mushrooms has become a research direction. However, the role of different drying techniques on shiitake mushroom quality is limited. Therefore, the purpose of this study was to investigate the effect of thermal and non-thermal drying on the drying kinetics, and the physicochemical properties of the end product. RESULTS: Results showed that shiitake mushroom treated with non-thermal drying (vacuum freeze-drying) had an attractive color, low shrinkage, and uniform honeycomb structure, while the drying time was the longest and not conducive to the formation of shiitake mushroom aroma. But shiitake mushroom treated with thermal drying presents an attractive fragrance. In thermal processing technology, compared with hot air convection drying (HAD), infrared hot air convection drying (IRHAD) shortens the drying time by 37.5%, and had the highest oxidation resistance, polysaccharide content and the lowest color change. Relative-humidity drying (RHD) samples had the lowest shrinkage compared with other thermal processing technology. The five polysaccharides exhibited similar preliminary structural characteristics, but the polysaccharides obtained by IRHAD have the highest antioxidant properties. CONCLUSION: These results showed that compared with thermal drying technology, non-thermal drying technology is not suitable for shiitake mushroom processing. In thermal processing technology, IRHAD is a potential drying method to obtain high-quality dried shiitake mushrooms and shiitake mushroom polysaccharide (SMP). However, it is necessary to increase the pretreatment technology to achieve the attractive appearance of non-thermal drying technology. © 2021 Society of Chemical Industry.

Wireless sensor networks for pharmaceutical lyophilization: Quantification of local gas pressure and temperature in primary drying.

Wireless sensor networks have become prolific in a wide range of industrial processes and offer several key advantages over their wired counterparts in terms of positioning flexibility, modularity, interconnectivity, and data routing. We demonstrate their utility in pharmaceutical lyophilization by developing a series of wireless devices to measure spatial variations in gas pressure and temperature during primary drying. The influence of shelf temperature, chamber pressure, excipient concentration, and dryer configuration are explored for various representative cycles using a laboratory-scale pharmaceutical lyophilizer. Pressure and temperature variations across the shelf for these cases are shown to vary up to 1.2 Pa and 10 °C, respectively. Experimental measurements are supported by computational fluid dynamics simulations to reveal the mechanisms driving the vapor flow. The measurements and simulation data are then combined to estimate the shelf-wise sublimation rate in the inverse sense to within a deviation of 3% based on comparison with gravimetric data. We then apply the sublimation rate profile to obtain the vial heat transfer coefficient and product mass transfer resistance for a 5% w/v mannitol formulation. Finally, these parameters are applied to a one-dimensional quasi-steady heat transfer model to predict the evolution of the product temperature over the course of primary drying. Thermocouple measurements of product temperature are compared directly to the simulated data and demonstrate accuracy comparable to existing published one-dimensional models.

Physicochemical and Quality Properties of Dried Courgette Slices: Impact of Vacuum Impregnation and Drying Methods.

The aim of this study was to determine the effects that the type of impregnating solution and drying method (freeze drying (FD) and vacuum drying (VD) at 45 °C and convective drying (CD) at 50, 60, and 70 °C) had on the physicochemical and quality properties of courgettes. Courgette slices were vacuum-impregnated (6 kPa) in freshly squeezed onion, kale, and onion and kale (50:50) juices with 3% NaCl solution (N). The application of vacuum impregnation (VI) with impregnating solutions from freshly squeezed onions and kale had a beneficial effect on the bioactive values of courgette. The highest contents of quercetin (41.84 µg/g d.m.) and carotenoids (276.04 µg/g d.m.) were found in courgette impregnated with onion juice after freeze drying. The highest values of lutein and zeaxanthin (216.42 µg/g d.m.) were recorded for courgette impregnated with kale juice and convective dried. By analysing the kinetics of convective drying, the best matching of the logistic model was found. Increasing the drying process temperature from 50 to 70 °C reduced the drying time from 15% to 36%, depending on the type of impregnating solution used. Water activity < 0.6 was recorded for courgette dried by freezing, vacuum, and convection at 60 and 70 °C. Conclusions: The vacuum impregnation process and the impregnation solutions from freshly squeezed vegetables can be used to develop new snacks with high levels of bioactive compounds. The FD method is the most appropriate considering both the bioactive compounds content and the obtained colour and water activity.

Effect of cold plasma pretreated hot-air drying on the physicochemical characteristics, nutritional values and antioxidant activity of shiitake mushroom.

BACKGROUND: Shiitake mushroom is one of the most popular delicious vegetables, although fresh shiitake mushroom has short shelf life as a result of biochemical degradation. Drying can prolong the shelf life of mushroom. Additionally, application of cold plasma pretreatments (CPT) before drying can preserve the product quality, processing costs and nutritional values. Therefore, we aimed to explore the effect of cold plasma pretreated hot-air drying at 50, 60 and 70 °C on the physicochemical characteristics, nutritional values and antioxidant activity of shiitake mushroom. RESULTS: Scanning electron microscopy micrographs showed that CPT induced the surface modification of fresh shiitake (such as cellular disarrangement, cellular shrinkages, disruption or break down of cell walls, and intracellular spaces and cavities) and facilitate the rapid drying than control samples. Furthermore, CPT improved the powder qualities (bulk density, water retention and swelling index) and preserved higher nutritional attributes (sugars, vitamins, phenolic acids contents and antioxidant activity) compared to the control groups. CONCLUSION: Conclusively, CPT could be a suitable alternative technique for improving drying characteristics and preserving nutritional attributes of agro-based products. © 2021 Society of Chemical Industry.

Economic analysis and drying kinetics of a geothermal-assisted solar dryer for tomato paste drying.

BACKGROUND: The economic value of many fruit and vegetables is often linked to the ability to preserve such natural products. In the case of tomatoes, the manufacture of 1 kg of powder or concentrate requires the evaporation of about 16 kg water kg-1 dry matter. In the present work, the effectiveness and economic analysis of solar drying systems for drying of tomato paste with and without geothermal water heat exchanger (GWHE) were studied. RESULTS: The GWHE integration significantly increased the recorded drying temperature up to 53.41 °C, with an improvement of 11.5 °C compared to the conventional dryer. Moreover, the drying temperature inside the drying chamber exceeded ambient temperature after sunset and at night by 30.8 °C. GWHE ensured a continuous drying process, while drying time was 22 consecutive hours, compared to the basic dryer with 18 h in 3 days. Effective moisture diffusivity was found to be 1.617 × 10-9 and 1.202 × 10-9  m2  s-1 for hybrid and basic drying systems, respectively, using the slope. Three methods were used to perform economic analysis. The cumulative present worth of savings, at 23 382.6 USD, is much higher than the capital cost of the hybrid dryer, at 467 USD. The payback period is quite acceptable, at 2.21 years as compared to dryer lifetime of 15 years. Therefore, the hybrid dryer will dry tomato paste without additional charges for 12.79 years and is recommended for a large-scale tomato paste dryer. CONCLUSION: The hybrid system with GWHE ensures a continuous drying process during night-time, in addition to reduced drying time. The economic study revealed a high feasibility for the hybrid dryer, with a short payback period. © 2021 Society of Chemical Industry.

Effect of drying methods on drying kinetics, energy features, thermophysical and microstructural properties of Stevia rebaudiana leaves.

BACKGROUND: Stevia leaves were subjected to convective hot-air, infrared and vacuum drying at 40, 60 and 80 °C, followed by an assessment of thermophysical properties and microstructure, along with drying kinetics modelling and evaluation of energy features for all drying operations. RESULTS: Effective moisture diffusivity (Deff ) showed dependency on temperature with values ranging from 1.08 × 10-12 to 7.43 × 10-12  m2  s-1 for convective drying, from 0.71 × 10-12 to 6.60 × 10-12  m2  s-1 for infrared drying, and from 1.29 × 10-12 to 5.39 × 10-12  m2  s-1 for vacuum drying. The thermal properties of the dried Stevia leaves under different drying conditions showed values of density, specific heat, thermal diffusivity, thermal conductivity and thermal effusivity ranging from 95.6 to 116.2 kg m-3 , 3050 to 3900 J kg-1  K-1 , 4.28 × 10-7 to 5.60 × 10-7  m2  s-1 , 0.16 to 0.23 W m-1  K-1 and 244 to 305 W s0.5  m-2  K-1 , respectively. As for microstructure, convective hot-air drying showed better preserved leaf characteristics, compared to infrared- and vacuum-drying, whereby scanning electron microscopy (SEM) image analysis also revealed noticeable differences at higher temperatures. Statistical analysis showed that the Midilli-Kuçuk model fitted best the experimental data of drying curves (0.961 < r2 < 0.999, 0.000064 < SSE < 0.005359, and 0.000074 < χ2 < 0.006278). Comparison of the drying methods with respect to energy features showed that convective drying at 80 °C led to lowest specific energy consumption (61.86 kW h kg-1 ) with highest efficiency (8.5%). CONCLUSION: The results of this study contribute to a better understanding of the drying behaviour and showed that thermophysical properties of dried Stevia leaves and energy features are affected by drying methods. © 2021 Society of Chemical Industry.

Intensive pulsed light pretreatment combined with controlled temperature and humidity for convection drying to reduce browning and improve quality of dried shiitake mushrooms.

BACKGROUND: The change of surface color caused by browning during the drying process of shiitake mushrooms seriously affects its market circulation. Intensive pulsed light (IPL) as a non-heat-treatment method can reduce enzyme activity by changing the enzyme structure. Therefore, in this study, the use of IPL pretreatment before drying was aimed to reduce the adverse reactions caused by the browning reaction during the drying processing of shiitake mushrooms. RESULTS: Shiitake mushrooms pretreated with 25 pulses of IPL energy of 400 J reduced the initial polyphenol oxidase enzyme activity, the browning index, and browning degree values by 42.83%, 43.02%, and 47.54% respectively. The IPL pretreatment enhanced the polysaccharides and reducing sugars contents and it reduced 5-hydroxymethylfurfural generation in the dried shiitake mushrooms. The pretreatment also improved the surface color, the antioxidant activity, and retained the umami taste characteristics in the dried shiitake mushroom. CONCLUSION: The IPL pretreatment combined with controlled temperature and humidity for convection drying could be a suitable method to improve the quality of dried shiitake mushrooms. Therefore, this study provides a new pretreatment method for materials that are prone to browning during drying. © 2021 Society of Chemical Industry.

Temperature and Concentration Dependence of Human Whole Blood and Protein Drying Droplets.

The drying of bio-colloidal droplets can be used in many medical and forensic applications. The whole human blood is the most complex bio-colloid system, whereas bovine serum albumin (BSA) is the simplest. This paper focuses on the drying characteristics and the final morphology of these two bio-colloids. The experiments were conducted by varying their initial concentrations, and the solutions were dried under various controlled substrate temperatures using optical and scanning electron microscopy. The droplet parameters (the contact angle, the fluid front, and the first-order image statistics) reveal the drying process's unique features. Interestingly, both BSA and blood drying droplets' contact angle measurements show evidence of a concentration-driven transition as the behavior changes from non-monotonic to monotonic decrease. This result indicates that this transition behavior is not limited to multi-component bio-colloid (blood) only, but may be a phenomenon of a bio-colloidal solution containing a large number of interacting components. The high dilution of blood behaves like the BSA solution. The ring-like deposition, the crack morphology, and the microstructures suggest that the components have enough time to segregate and deposit onto the substrate under ambient conditions. However, there is insufficient time for evaporative-driven segregation to occur at elevated temperatures, as expected.

Effects of pre-cutting treatments and combination drying with different orders on drying characteristics and physicochemical properties of Lentinula edodes.

BACKGROUND: Combination drying is recognized as an energy-efficient method utilized for dry product processing, and proper order of combination is a critical factor determining the effectiveness of the technique. In this study, hot air drying (HD), vacuum freeze-drying (VFD), and combination drying with different orders (HD-VFD and VFD-HD) are performed on whole Lentinula edodes and pre-cut (half-cut and quarter-cut) L. edodes. The effects of various cutting and drying approaches on drying characteristics, physicochemical properties, and microstructures of dried L. edodes were investigated. RESULTS: The longest processing time required to dry the whole L. edodes by VFD was 25 h. In contrast, the pre-cutting treatment and combination drying certainly shortened the drying time. Compared with HD, use of VFD-HD and VFD significantly decreased the shrinkage ratio, hardness, and discoloration of dried products but increased the rehydration capacity, nutrient retention, and porous microstructure. Interestingly, switching the order of combination drying provoked entirely different drying effects. Specifically, HD-VFD triggered negative effects on the shrinkage and color of dried mushrooms, and its appearance color was similar to HD-treated samples. Moreover, pre-cutting dramatically enhanced the protein content of HD-treated mushrooms, and the quarter-cut samples obtained the highest level (21.69 g kg-1 dry basis) among the three types of cutting. CONCLUSIONS: The dried L. edodes processed through pre-cutting and combination drying (VFD-HD) have optimal industrial quality, accompanied by shorter processing time. © 2020 Society of Chemical Industry.

Vacuum microwave dehydration decreases volatile concentration and soluble protein content of pea (Pisum sativum L.) protein.

BACKGROUND: Peas are an inexpensive yet nutritious and sustainable source of protein. However, it is challenging to incorporate pea proteins into food formulations owing to their beany or green off-flavours and their limited water solubility. RESULTS: Vacuum microwave dehydration (VMD) of pea protein with an initial moisture content of 425% (dry basis, db) at 2 W g-1 specific microwave energy and 200 Torr vacuum level for 88 min led to an 83% reduction in total volatile compound concentration. VMD processing at high initial moisture contents facilitated the Maillard reaction, enhancing the extent of protein cross-linking, leading to a marked decrease in soluble protein content, to 11 g kg-1 . Reducing the initial moisture content to 56% db greatly retained protein solubility (112-113 g kg-1 ), but it only led to a minor reduction in total volatile compound concentration (2-11% reduction). A high microwave energy (20 W g-1 )-short time (2 min) treatment at 200 Torr vacuum level was found optimal, reducing both volatile levels and soluble protein content by ~50%. CONCLUSION: Evidently, it is difficult to employ VMD without reduction of pea protein solubility and corresponding changing in functionality. Yet, if optimized, VMD has the capability to decrease volatile concentrations while retaining protein solubility. Future sensory analysis should be conducted to determine whether the aforementioned reductions in total volatile compound concentration may have a notable effect on consumer palatability. © 2020 Society of Chemical Industry.

A fully coupled multiphase model for infrared-convective drying of sweet potato.

BACKGROUND: Combined infrared (CIR) and convective drying is a promising technology in dehydrating heat-sensitive foods, such as fruits and vegetables. This novel thermal drying method, which involves the application of infrared energy and hot air during a drying process, can drastically enhance energy efficiency and improve overall product quality at the end of the process. Understanding the dynamics of what goes on inside the product during drying is important for further development, optimization, and upscaling of the drying method. In this study, a multiphase porous media model considering liquid water, gases, and solid matrix was developed for the CIR and hot-air drying (HAD) of sweet potato slices in order to capture the relevant physics and obtain an in-depth insight on the drying process. The model was simulated using Matlab with user-friendly graphical user interface for easy coupling and faster computational time. RESULTS: The gas pressure for CIR-HAD was higher centrally and decreased gradually towards the surface of the product. This implies that drying force is stronger at the product core than at the product surface. A phase change from liquid water to vapour occurs almost immediately after the start of the drying process for CIR-HAD. The evaporation rate, as expected, was observed to increase with increased drying time. Evaporation during CIR-HAD increased with increasing distance from the centreline of the sample surface. The simulation results of water and vapour flux revealed that moisture transport around the surfaces and sides of the sample is as a result of capillary diffusion, binary diffusion, and gas pressure in both the vertical and horizontal directions. The nonuniform dominant infrared heating caused the heterogeneous distribution of product temperature. These results suggest that CIR-HAD of food occurs in a non-uniform manner with high vapour and water concentration gradient between the product core and the surface. CONCLUSIONS: This study provides in-depth insight into the physics and phase changes of food during CIR-HAD. The multiphase model has the advantage that phase change and impact of CIR-HAD operating parameters can be swiftly quantified. Such a modelling approach is thereby significant for further development and process optimization of CIR-HAD towards industrial upscaling. © 2020 Society of Chemical Industry.

Ultrasonic and osmotic pretreatments followed by convective and vacuum drying of papaya slices.

BACKGROUND: Papaya fruit is highly nutritive, but very fragile, and thus has a limited shelf life. Drying is essential to preserve it for longer durations. In this work, osmotic dehydration (OD) with and without ultrasound (US) was applied to papaya slices as a pretreatment in conjugation with vacuum (VD) and convective air drying (AD). Drying was carried out in a novel dryer. Moisture content, drying time, water activity, total color change, total phenolic content, radical scavenging activity, texture, and Fourier-transform infrared (FTIR) spectrums were evaluated for fresh and dried papaya slices. RESULTS: It was observed that US-assisted osmotic dehydration (USOD) followed by VD had the lowest drying time with highest retention of phenols and antioxidants as compared to other drying techniques. Higher phenols and antioxidants in US-pretreated samples were attributed to the release of trapped intra-cellular polyphenols by cavitation. However, the color characteristics and texture of OD pretreatment followed by convective AD slices were found to be better. Color retention could be due to carotenoid preservation, which would be degraded in other treatments, whereas lower brittleness was associated with lower pectin. Infrared spectroscopy confirmed the retention of phytochemicals and antioxidants in dried papaya slices that were subjected to pretreatment. CONCLUSION: Pretreatment before drying enhances the end product quality of dried papaya slices. The results of this study highlight that USOD-VD is effective for nutrition preservation while OD-AD is suitable for preserving physical characteristics. © 2020 Society of Chemical Industry.

Comparison between airborne ultrasound and contact ultrasound to intensify air drying of blackberry: Heat and mass transfer simulation, energy consumption and quality evaluation.

This study aimed at investigating the performances of air drying of blackberries assisted by airborne ultrasound and contact ultrasound. The drying experiments were conducted in a self-designed dryer coupled with a 20-kHz ultrasound probe. A numerical model for unsteady heat and mass transfer considering temperature dependent diffusivity, shrinkage pattern and input ultrasonic energies were applied to explore the drying mechanism, while the energy consumption and quality were analyzed experimentally. Generally, both airborne ultrasound and contact ultrasound accelerated the drying process, reduced the energy consumption and enhanced the retentions of blackberry anthocyanins and organic acids in comparison to air drying alone. At the same input ultrasound intensity level, blackberries received more ultrasound energies under contact sonication (0.299 W) than airborne sonication (0.245 W), thus avoiding the attenuation of ultrasonic energies by air. The modeling results revealed that contact ultrasound was more capable than airborne ultrasound to intensify the inner moisture diffusion and heat conduction, as well as surface exchange of heat and moisture with air. During air drying, contact ultrasound treatment eliminated the gradients of temperature and moisture inside blackberry easier than airborne ultrasound, leading to more homogenous distributions. Moreover, the total energy consumption under air drying with contact ultrasound assistance was 27.0% lower than that with airborne ultrasound assistance. Besides, blackberries dehydrated by contact ultrasound contained more anthocyanins and organic acids than those dried by airborne ultrasound, implying a higher quality. Overall, direct contact sonication can well benefit blackberry drying in both energy and quality aspects.

Effect of different drying methods on product quality, bioactive and toxic components of Ginkgo biloba L. seed.

BACKGROUND: Ginkgo biloba seeds are used as a functional food across Asia. However, the presence of toxic compounds has limited their application. In this study, freeze drying, infrared drying, hot-air drying and pulsed-vacuum drying were used to dry G. biloba seeds. A comprehensive analysis was performed on their product quality, antioxidant activities, bioactive and toxic components. RESULTS: Results showed that the drying methods had a significant influence on product quality with freeze drying being superior due to the minimal microstructural damage, followed by infrared drying and pulsed-vacuum drying. Infrared-dried product possessed the strongest antioxidant activities and higher bioactive compound content than hot-air-dried and pulsed-vacuum-dried product. Toxic compounds in fresh G. biloba seeds (ginkgotoxin, ginkgolic acid and cyanide) were reduced markedly by drying. Ginkgotoxin was reduced fourfold, and the contents of acrylamide, ginkgolic acid and cyanide in dried G. biloba seeds were reduced to the scope of safety. Amongst the four drying methods, infrared drying had the shortest drying time, and its product showed higher quality and bioactive compound content, and stronger antioxidant activities. CONCLUSIONS: These findings will offer salient information for selecting a drying method during the processing of ginkgo seeds. Infrared drying could be considered as a multiple-effect drying method in the processing of ginkgo seeds. © 2020 Society of Chemical Industry.

Effects of tri-frequency ultrasound-ethanol pretreatment combined with infrared convection drying on the quality properties and drying characteristics of scallion stalk.

BACKGROUND: Having short drying time and attractive product quality are important in fruit and vegetable dehydration processing. In this work, tri-frequency (20, 40 and 60 kHz) ultrasound-ethanol pretreatment, ultrasound-water pretreatment and ethanol pretreatment were employed before infrared convection drying (ICD) of scallion stalks, which was aimed at improving the drying process and quality of the end products. The mass transfer, drying characteristics (moisture ratio and drying rate and quality properties of scallion (rehydration, color, flavor, optical microscope image, moisture distribution and microbiological quality) were analyzed. RESULTS: All pretreatments have decreased the drying time by 33.34-83.34% compared to the control, while ultrasound-ethanol pretreatment provided the highest time reduction (83.34%). The reason is that the volatility of ethanol have replaced air in the tissue, which produced a better osmotic dehydration effect and the cavitation effect of ultrasound changed the cell function of the material, so that the food tissue was rapidly compressed and expanded, resulting in damage to the cell structure. Ultrasonic-ethanol pretreatment has greatly reduced the water loss and dry matter of fresh scallion, improved the rehydration effect of dried scallion, better retained the color and flavor of scallion and effectively reduced the microbiological quality of the scallion. CONCLUSION: The tri-frequency ultrasound-ethanol pretreatment has effectively improved the drying process and quality characteristics of the dried scallion. Therefore, this research has a great contribution to the drying technology, as evident in the remarkable reduction in drying time and the improvement in the quality of the end product. © 2020 Society of Chemical Industry.

Preservation of Aloe vera and soybean flour fortified Granny Smith apple through optimised quartz-halogen radiated vacuum drying: kinetics and quality evaluation.

BACKGROUND: Granny Smith (GS) apple has low protein content and poor antimicrobial properties; hence it has been blended with Aloe vera (AV; high ascorbic acid, antimicrobial and antioxidant properties) and soybean flour (SF; rich in phenols, flavonoids, ascorbic acid, total antioxidant and protein) in different proportions to obtain fortified GS, i.e. GSAVSF. Moreover, GS being a perishable fruit, its moisture content should be reduced to enhance shelf life. Accordingly, this GSAVSF was osmotically pre-dehydrated and finally dried through energy-efficient quartz-halogen radiation (QHR) assisted vacuum-drying (QHRVD) to produce dried GSAVSF i.e. (DGSAVSF) under optimized conditions. RESULTS: The optimally dehydrated DGSAVSF product resulted in minimum moisture (4.85% w/w) and maximum protein (6.24 g kg-1 ) content. The application of osmotic dehydration and QHRVD afforded acceptable colour of DGSAVSF compared to GSAVSF (ΔEI * = 10.07 ± 0.21). A parametric drying model was formulated that corroborated well with Fick's equation. QHRVD rendered high moisture diffusivity (1.49 × 10-8 m2 s-1 ) and low activation energy (27.64 kJ mol-1  K-1 ). Appreciable quality improvements with respect to fresh GS concerning ascorbic acid (176.05%), total phenolic (579.07%), total flavonoid (333.33%) contents and 2,2'-diphenyl-1-picrylhydrazyl radical scavenging activity (446.71%) could be achieved. The product demonstrated satisfactory shelf life (1 × 104 CFU g-1 : aerobic mesophilic; 1 × 104 CFU g-1 : mould and yeast) and high rehydration ratio (4.25 ± 0.1). CONCLUSION: The enrichment of GS with AV and SF along with optimal drying protocols could provide a quality fortified DGSAVSF through an energy-proficient sustainable process. The highly nutritious product with suitable colour, microbial stability and rehydration ratio also satisfied a 9-point hedonic scale, thus confirming consumer acceptability. © 2020 Society of Chemical Industry.

Vacuum Dehydration: An Excellent Method to Promote the Formation of Amadori Compounds (ACs, N-(1-Deoxy-d-fructos-1-yl)-amino Acid) in Aqueous Models and Tomato Sauce.

Amadori compounds (ACs; N-(1-deoxy-d-fructos-1-yl)-amino acid) are superior flavor precursors and potential functional ingredients in food processing. In this study, vacuum dehydration as an excellent and universal method for the formation of ACs in both simulation systems and food processing was revealed. In total, 12 amino acids referring to all six categories were selected to conduct simulated reactions with glucose in aqueous models. At 90 °C, yields of 11 ACs were significantly increased by vacuum dehydration, reaching 4-198 times compared to a heat sealing reaction in aqueous systems, and formation of 5-hydroxymethyl-2-furaldehyde (5-HMF) and browning were slower than that by a dry powder reaction. In particular, the yields of Fru-Arg, Fru-His, and Fru-Glu reached 87.03, 90.73, and 89.88 mol %, respectively. The order of promotion effect was acid ACs > basic ACs > unique ACs > polar neutral ACs > aliphatic ACs > aromatic ACs. The excellent effect was mainly attributed to the control of water activity (Aw) and pH, which enabled the models to reach the optimal reaction state quickly by adjusting the vacuum degree at mild temperatures. The method was also applied to AC enrichment in tomato sauce processing; the AC content could rise to 30.72 mg/g, which was more than 17 times than those in samples without vacuum dehydration and two commercial tomato sauces.

Freeze-drying in protective bags: Characterization of heat and mass transfer.

During lyophilisation of highly potent Active Pharmaceutical Ingredients (APIs) potential contamination of the freeze-drier is an important safety issue. Since the stoppers are in semistoppered position during the lyophilization process, API may contaminate the chamber and cross-contamination may occur as well. In this study two protective bags, which enclose each tray and their influence on heat and mass transfer during freeze-drying were investigated. Sublimation tests were performed using either purified water or solutions containing trehalose as well as hydroxypropyl-ß-cyclodextrin (HPbCD) as bulking agents. During sublimation tests with purified water both bags clearly influenced heat and mass transfer compared to unpacked reference vials. The bag, which was originally designed to be used for steam sterilization, had a massive impact on drying characteristics. The bag membrane becomes the rate limiting factor, generating a separate compartment within the bag. In this compartment vapor pressure is much higher compared to the chamber pressure during primary drying, leading to altered drying conditions. However, drying was still possible. The other bag, which was specifically designed for lyophilization, also had an impact on drying behavior which could be assigned to the foil between shelf and bottom of the vials. This was detectable as differences in Kv values. Membrane resistance, however, becomes negligible when 10% (w/w) trehalose or HPbCD solutions were dried using the later bag as containment. The data reported in this work demonstrate the relevance and value of sublimation tests to understand the lyophilization process, especially when new components are implemented. The data should be considered, when freeze-drying shall be performed using such bags.

Mechanism insights into the transformation of carbosulfan during apple drying processes.

The transformation of carbosulfan (CSN) in apples was investigated during oven-drying, microwave drying, and sun-drying. CSN transformed primarily into carbofuran (COA) during these drying processes. The conversion kinetics of CSN and COA was fitted by curve regression and mainly conformed to quadratic models (R2 = 0.70-0.97). Oven-drying promoted the transformation of CSN into COA. Microwave drying resulted in the highest scavenging capacity against CSN and COA (41%-100%). Moreover, a transformation mechanism was proposed on the basis of density functional theory (DFT) calculation. The COA originated from a series of chemical reactions involving hydroxyl substitution, cleavage, and oxidation; this result was further confirmed on the basis of molecular electrostatic potential (MEP) and molecular orbital theory. Furthermore, the toxicity and stability of CSN and COA were evaluated with the T.E.S.T. program. COA was less toxic than CSN to aquatic organisms but more toxic than CSN to rats. Therefore, COA production should be avoided during drying. Microwave drying was found to be the optimum choice for drying apples.