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The textile industry produces harmful effluents that are discharged into the environment, damaging the aquatic and other ecosystems. A yeast-based solution for decolorization of textile industrial wastewater was produced and evaluated. Three yeast strains, Candida parapsilosis (HOMOGS20B), Yarrowia lipolytica (HOMOGST27AB) and Candida pseudoglaebosa (LIIIS36B), isolated from a textile wastewater treatment plant and previously selected for their dye decolorization capacity, were freeze-dried. Additionally, Yarrowia lipolytica (HOMOGST27AB) was also spray-dried. Skim milk powder and maltodextrin were used as cell protectors, and the freeze-dried products were stored at cold (4 °C) and room temperature for 210 days. The viability of the yeast cells and their decolorization capacity over time were assessed. Dried yeast cells maintained their viability, and decolorization capacity for at least 90 days of storage after spray- and freeze-drying with both cell-protecting agents. The dried yeast-based solution for decolorizing textile industrial wastewater combines stability, efficiency, and convenience of production for application in real industrial facilities.

The abundance of fish catches in Indonesia is excellent potential. Still, if the abundant results cannot be adequately managed and are just wasted, it will eventually lead to bad things. This problem was also found in Seraya village, Karangasem, Bali, where large fish yields and the fish processing process were still constrained by weather and environmental conditions causing the expected results to not be achieved. To overcome this, a photovoltaic (PV) system-based fish dryer was developed that can assist the fish drying process. Utilization of this system is also supported by good solar energy potential. The system can generate 402.78 Wh of electrical energy per day, covering 104.89% of the electrical energy demand of the fish dryer. The results of statistical tests using the Mann-Whitney test for fish weight and unpaired t-test for fish moisture content showed no significant results (p0.05). This value states that there is no difference in the results of drying fish with the PV system and the traditional method. From this, we can conclude that fish drying using a solar power system works similarly to conventional fish drying methods.

The leaf extracts of Gymnema sylvestre consist of secondary metabolites which are well known for antioxidant activity. This study aimed to measure the drying characteristics of G. sylvestre leaves under far-infrared radiation (FIR) and to optimize the specific energy consumption for drying and antioxidant activity of ethanol-water extract of dried leaves. Fresh leaves were harvested and exposed to combinations of four different temperatures (125, 150, 175 and 200 °C) and exposure times (5, 10, 15 and 20 min). Drying kinetics, energy consumption, color changes, total phenolic content (TPC) and antioxidant activities were quantified. Both temperature and drying time have significant (p < 0.05) effects on drying characteristics and antioxidant activity. The equilibrium moisture content was achieved at 200 °C and 18 min. The specific energy decreased and total color changes increased with temperature. Under lower temperatures (125 and 150 °C), TPC and antioxidant activity increased with exposure time, whereas higher exposure time (20 min) with high temperatures (175 and 200 °C) significantly decreased TPC and antioxidant activity. The highest TPC of 30.5 mg TAE/g leaf-fresh weight was achieved at 200 °C and 15 min. The optimal drying conditions achieved from the dissimilarity function method were 200 °C and 8.4 min.

Turmeric (Curcuma longa L.) is one of the spices commonly used globally due to its health-promoting properties. The rhizomes are however perishable due to their high water content. In this study, the effect of different pretreatments and drying methods, viz. hot air drying (HAD) at 60 ℃ and forced air solar drying (FASD), on the drying kinetics, water activity, color, ß-carotene, and vitamin C contents of turmeric rhizomes were investigated. Prior to the experiments, fresh turmeric rhizomes were sliced into 3 mm thickness and treated either by steam blanching or immersion in an ascorbic acid solution. The untreated samples served as a control. The results showed that blanching and ascorbic acid treatments decreased the drying time by 11% and 31% each under the HAD and 30% and 18% under FASD when compared with the control, respectively. The water activity of steam blanching, ascorbic acid, and control samples dried under HAD and FASD was below 0.60, which is sufficient to inhibit spoilage. Ascorbic acid pretreated samples dried under HAD, and FASD resulted in significantly (P 0.05) by the pretreatment, drying method, and their interaction. In conclusion, pretreating turmeric rhizomes with the ascorbic acid solution before HAD at 60°C will be ideal for preserving the color properties, vitamin C and β-carotene contents.

Comprehensive studies into the influence of various types of preliminary preparation of blueberry berries for drying have established the amount of wax coating, color, and the total duration of dehydration of raw materials. A comparison of 2 types of preliminary preparation was made: hygrothermal treatment and infrared radiation treatment directly during drying. It was established that after treatment with infrared radiation, 53 times more wax plaque came off the berries than after hygrothermal treatment. Microscopic studies of sections of the parenchymal part of berries recorded the state of the cell membranes and the color of the raw materials without prior processing, with pretreatment, and after drying. It was found that berries dried without pretreatment (mode parameters of heat carrier: t=70°C, v=2m/s, d=10g/kg dry air. Win=85%, ) have partially destroyed cell membranes but the color of the dried material is preserved to the maximum. It was observed that the berries after hygrothermal treatment have partially destroyed parts of the cell membrane, which makes it possible to more intensively release moisture from the material after drying, the maximum color of the product is also preserved. In berries, after treatment with infrared radiation of 100 W for 10 minutes, the cells remain convex with partial destruction of the shell of some cells but, after pretreatment, the intensity of color decreases. Studies into the kinetics of drying blueberry berries have confirmed that the use of infrared radiation with a capacity of 100 W for 10 minutes with simultaneous drying under the regime parameters of the heat carrier t=60°C, v=3m/s, d=10g/kg dry air. makes it possible to reduce wax coating on blueberry berries and to intensify thermal moisture exchange during drying of berries better than using hygrothermal treatment

Slices of fresh apple, banana and strawberry were frozen at -20 oC and freeze-dried using a shelf temperature of 40 oC. Theoretical expressions were proposed to predict vapor transfer kinetics during the primary and secondary drying stages. In the former, a model that predicts the sublimation rate as a function of time, considering the increasing dried layer thickness, was used, which improves greatly the sublimation time equation offered in several textbooks without adding much complexity. In the latter, an analytical solution of the unsteady state diffusion equation was applied. Permeabilities were determined for the primary drying model at an absolute pressure of about 30 Pa, though the relevant kinetic coefficient combines permeability and the mass of ice to sublime relative to the dry matter (sublimation kinetic coefficient). In the secondary drying stage, diffusion coefficients of vapor in the dried layer were in the order of 10−09 m2 s−1 for pressures of about 3-5 Pa. In both periods, agreement of predicted and experimental values was more than satisfactory. A minimum freeze-drying time of 12, 6.8 and 8.7 h, considering a final moisture content of 4% w/w, was calculated for apple, banana and strawberry, respectively. Normalized drying curves showed a faster sublimation rate for banana, intermediate for strawberry and slowest for apple. On the other hand, desorption curves showed a faster desorption rate for apple, intermediate for banana and slower for strawberry. In each period, the ordering of the relevant kinetic coefficients (sublimation and diffusion coefficients, respectively) represented the ordering of experimental curves., Centro de Investigación y Desarrollo en Criotecnología de Alimentos, Facultad de Ingeniería

This work investigates the equilibrium stage of the crack propagation of a fine-grained soil after several drying and wetting cycles (shrinkage and swelling hysteresis). This stage is found to be crucial in practical engineering since the soil continues to show its irreversible hydraulic settlement, which is a potential risk for some severe structural damages. The shrinkage area and the shrinkage crack area were determined by using the image processing method. For the cyclic experimental investigations, the shrinkage cracks were followed during six months of successive wetting and drying cycles for two samples (with two different initial water contents). These long-term tests were completed by some short term single drying path tests performed on samples prepared at different initial states. The results showed the existence of a unique equilibrium stage at the end of the wetting and drying cycles for the two studied samples. The equilibrated soil subsidence was separated into two parts: the reversible settlement of the equilibrium stage and the irreversible settlements cumulated during successive wetting and drying cycles. At the equilibrium stage, the reversible deformation was 5.9% and the irreversible deformation was 3.8%. A simplified theoretical approach was also used to predict the cracking equilibrium stage and its soil subsidence. The fitted parameters of the theoretical approach for each cycle were stabilized to confirm the existence of this equilibrium stage.

Technological comparison and system modelling of sewage sludge treatment are important in terms of sustainable development and climate change mitigation. Dewatering and drying are important processes for reducing volume for transportation and often a requirement for further sludge treatment. Inventory data on mass transfers and material and energy consumptions are therefore crucial in improving and understanding sludge management systems. Reviewing the scientific literature (2003–2021) revealed 55 and 21 datasets on dewatering and drying of sewage sludge, respectively. The scarcity of data did not allow for identifying detailed relationships between inputs and outputs for the technologies, but the reviewed data can serve as the first port of call when planning sludge management. The average total solid (TS) content obtained was statistically different for mechanical dewatering (MDW), deep dewatering, bio-drying (BDR) and thermal drying (TDR). Loss of volatile solids (VS) during dewatering is barely described, but a substantial VS loss was observed for TDR (8%) and BDR (27%). The use of chemical agents in MDW showed typical values of 5–15 g kg−1 TS. The use of energy is low for MDW (average of 0.12 and 0.26 kWh kg−1 TS for raw and digested sludges, respectively) but substantially higher for TDR (average of 3.8 kWh kg−1 TS). The justified inventory data for sludge dewatering and drying provide essential support to system modelling and technological comparison in future studies, but additional data from full-scale plants on energy consumption and the composition of removed water are strongly requested to improve the inventory.

The effect of drying temperature on drying characteristics of cooked and fermented palm nuts were determined. The samples were processed using two methods (cooking and fermentation). The rate of drying the samples was observed to increase with corresponding increase in temperature and drying time. It was duly observed that at 70C, Tenera sample (TS), Pisifera sample (PS) and Dura sample (DS) attained their constant drying rates at 720 mins, 600 mins, and 780 mins. At 80C TS, PS and DS drying rates falls to zero at 660mins, 600 mins and 720 mins, for 90C drying temperature, TS and PS had same constant drying rate at 540 mins, DS constant drying rate was found at 600mins. For 100C TS constant drying rates was observed at 480mins while PS and DS had same constant drying rate at 420mins respectively. The effective drying of the samples was observed to occur at falling rate across the varieties and processing methods. The lower temperature (70C) decreased the drying rates while the higher temperature increased the drying rates. The average drying time for cooked samples irrespective of sample varieties were 740 mins, 620 mins, 460 mins and 500 mins for temperature range of 70-100C respectively while for the fermented samples, the average drying time were 680 mins, 660 mins, 560 mins and 440 mins at temperature range of 70-100C respectively. The regression equations were found to give the best fit with highest coefficient of variation (R2) values. Mostly all the samples irrespective of processing methods exhibited quadratic regression equations. The cooked samples displayed better dry characteristics than fermented samples.

Drying is among the beneficial food preservation strategies and this method ensures food products last before they reach consumers. The most used drying method is direct drying under the sun. However, in this method, the negative effects of the external environment damage food products. Recently, solar drying systems have been the main subject of much research as they have been protecting food from the negative effects of the external environment. In this study, a solar drying system (SD), which have a drying chamber with different structure, was used for drying mushroom. At the same time, mushroom slices were dried under open sun (OSD) for observing the performance of drying system. Drying rate (DR) and moisture ratio (MR) values were determined from the experiments. In addition, the MR values obtained from the experiments were estimated by 6 different mathematical models and 6 different machine learning algorithms. According to the results of the experiments, the drying time of the mushroom slices using SD was approximately 12.4 hours less than the drying time under open sun. The best convergence in the results gathered from the mathematical models is Sripinyowanich and Noomhorn and Hii et al. models for SD and OSD, respectively. The best estimation for MR values was realized by the Multilayer Perception algorithm for both drying methods.

Energy use, together with consumption of raw materials, machine clothing, and wet end chemicals, are some of the most critical aspects in successful tissue making today. This work was aimed at developing a laboratory-scale method of estimating dewatering mechanisms, vacuum efficiency, and energy use of Through Air Drying (TAD) of tissue. When compared to pilot data, the results of the new laboratory method for investigating dewatering during TAD were in the same magnitude, around 24 to 26% dryness after vacuum dewatering, and 27 to 29% dryness after TAD molding. Sheet properties, such as caliper and surface profile, were evaluated and compared to commercial tissue sheets. The results indicate that it will be possible to precisely measure accurate dryness development and penetrated air volume for tissue sheet forming and TAD molding at a laboratory scale. This can contribute to the efforts of implementing a circular forest-based bioeconomy by increasing the fundamental understanding of dewatering of tissue paper materials, which is facilitated by improvements in energy use. The new method developed in this work will make it easier to assess ideas that are difficult to bring to pilot scale or full scale before learning more of the dewatering capabilities. The authors are convinced that improved knowledge of tissue dewatering mechanisms, forming, and material transport during and after TAD dewatering can increase the efficiency of the industrial manufacturing processes.

The effects of lactic acid concentration (LA) and spray drying conditions on stickiness of acidified skim milk powder (SMP), which impacts process efficiency and powder properties, were examined using a fully replicated 24-1 fractional factorial design. The wall deposition was significantly affected by LA, and yield was positively influenced by the drying temperature difference. Drying temperature difference significantly affected particle size, moisture content and water activity of acidified SMP. Particle size was also significantly influenced by nozzle airflow rate. Moisture content and water activity were significantly affected by LA, while glass transition temperature was only influenced by the outlet temperature.

Most agricultural crops with high moisture content are difficult to preserve. The most common method of preservation is drying. Thus, drying operation where a combination of two or more modes is used, could speed-up drying process. However, the scalability of combined heated air and infrared drying (CHAID) for rural consumers have not been investigated. This study was conducted to examine the effect of drying conditions (temperature and infrared intensity) on the drying kinetics and total colour changes (∆E) of plantain slices using a CHAID dryer. Matured unripe plantain samples were sourced from a market, peeled, washed in running water and then sliced into 4 × 20 × 20 mm dimension. Initial moisture content (MCi) determined using oven drying method. 2.0 g of the sliced sample were weighed and dried in a combined heated air and infrared dryer (IR) operated at 800 W/m2 alone till the mass (bone dry mass) did not vary after repeated weighing. Also, samples ∆E was monitored using colorimeter within the drying period. The same procedure was repeated using heated air-drying mode (HAD) operated at 65 ± 2 °C; IR-800 W/m2 plus HAD at 65 ± 2 °C, and IR-1000 W/m2 plus HAD at 65 ± 2 °C. The moisture content (MC) and drying rate were computed from duplicate data using Microsoft Excel programme. The variation of % MC with drying time, drying rate against MC and ∆E versus drying time were made and ∆E compared using Tukey Honest Significant Difference. Results showed that the samples’ MCi by oven dried method was 55.84%wb whereas those dried using IR-800 W/m2 alone, HAD (65 ± 2 °C) alone, IR-800 W/m2 plus HAD (65 ± 2 °C) and IR-1000 W/m2 plus HAD (65 ± 2 °C) modes were 57.43, 52.13, 57.41 and 57.03% wb, respectively, and their corresponding critical or equilibrium moisture content were 5.62, 5.03, 12.45 and 5.95%wb, respectively. Similarly, a shortest drying time (30 mins) and minimal total colour changes (ΔE = 12.42) were found when IR (1000 W/m2) plus HAD (65 ± 2 °C) was used. It also observed that, plantain slices dried using HAD (65 ± 2 °C) mode showed statistically significant mean difference in ΔE when compared with other three drying modes within 10 to 30 minutes drying time. Since, IR (1000 W/m2) plus HAD (65 ± 2 °C) mode gave shortest drying time and minimal ΔE, it is recommended for use in drying plantain slices by restaurant, hotels operators and food processors. &nbsp

Encapsulation is one of the most widely utilized strategies for preventing oil oxidation. Chia oil is a source of oils that are high in omega-3s and was used as a core material in this study. Whey protein and gum arabic were used as wall materials, and the whey protein:gum arabic ratios were 1:0, 1:1, 1:2, 2:1, 1:3 and 3:1. Preparation of chia oil microcapsules was conducted by spray-drying or freeze-drying methods. All microcapsules were stored in an opaque and airtight laminate pouch for 3 and 6 months to determine the effect of time on the fatty acid composition, encapsulation efficiency and chemical properties. Encapsulation had a positive protective effect on oil quality. The two drying methods resulted in different powder characteristics: spray drying resulted in a spherical shape, whilst freeze drying led to flakes and a porous surface. Spray drying microcapsules resulted in greater encapsulation efficiency than freeze drying microcapsules. In addition, encapsulated powders stored for 6 months showed both acid and peroxide values below the Codex limit. These results indicate a possible encapsulation process to protect chia oil from oxidation.

Moringa oleifera Lam. is an incredible plant because of vital nutrients such as minerals, vitamins and phytochemicals. The present work is focused on studying the optimization and quality attributes retention in moringa flowers in a freeze dryer (FD). Because the conventional drying process takes more time and energy which will affect the product quality and safety. Response surface methodology (RSM) was employed to optimize the effect of drying temperature (- 65 to - 45°C), vacuum pressure (0.5 to 2.5 mmHg) and drying time (18 to 24 h.) on the vitamin C, total antioxidant activity(TAA) and hygroscopicity (HS) of moringa flower. The developed model response R2 values of vitamin C 0.96, total antioxidant activity 0.97 and hygroscopicity0.95. Based on response surface and desirability (0.74) functions, moringa flower was freeze sdried at - 63.75°C for18 hr under 0.55 vacuum pressure had an optimum level of vitamin C 285.84 mg/100g, TAA 453.20 mg/100g and HS 1.57 percent. Freeze dried moringa flower powder at -55°C had maximum drying characteristics with special reference to high powder recovery (98.75%) and excellent flowability.The first principal component, accounting for 52.15 per cent and two 23.02 per cent of the total variance resolved the different drying temperatures.

Most drying methods combine convective, conductive and radiation heat transfer processes. The share of each type of heat transfer may vary depending on the type and mode of drying, type of product, etc. In this study, the problem of determining the heat transfer mechanism of vacuum drying of solid-moist and liquid-viscous materials is solved. The objects of the study are Jerusalem artichoke tubers, camel and mare milk. The numerical values of the heat transfer components are found experimentally and their shares in the total heat flux are determined. During vacuum drying of Jerusalem artichoke at a medium pressure of 4kPa and a temperature of 55°C (with a layer height of 0.01 and 0.02 m), the convective component predominates (58.55 and 67.65%). The share of thermal conduction (18.96 and 29.39%) and radiation (13.39 and 12.05%) is much lower. The mechanism of thermal conduction begins to prevail with an increase in the height of the material layer (0.03 and 0.04 m). The convective component is also dominant for vacuum drying of milk: at medium pressures of 6÷10kPa and a temperature of 40°C, its value for mare milk reaches 78.21%, for camel milk – 73.33%. The second most important is the share of radiation (19.45 and 22.58%). Conductive heat transfer has the minimum indicators (5.66 and 6.17%). The large values of the share of thermal conduction during drying of Jerusalem artichoke compared to milk are explained by the fact that heat transfer occurs inside the tubers due to conduction, and inside milk – due to convection. Insignificant shares of radiation are explained by low and medium vacuum values in the chamber. In the studied range, heat and mass transfer occurs due to molecular diffusion and convection. The results obtained can be used to formulate criterion heat transfer equations, in engineering calculations, and optimization of the vacuum dryer operation.

Color of dried edible material is one of the most essential considerations for consumers when making product purchases. The similarity between the color of the dried product and the color of the fresh product increases their marketability. The primary objective of drying operations is to dry products with minimal energy consumption, to prevent the growth of microorganisms, preserve their flavor and nutritional value, to make the moisture content suitable for storage, and to ensure that the color change after drying closely resembles that of the fresh product. This study seeks to dry Oyster mushrooms (Pleurotus spp.) at different drying power levels (90 W, 180 W, 360 W, and 600 W) using the microwave drying method of thin slices and to determine the color changes of the dried mushrooms. As a result of the trials carried out in the laboratory, it was discovered that the increase in drying power caused the samples to dry faster. At the end of the drying period, the colors of the mushrooms became darker than the initial levels. The highest change in brightness was recorded during the drying process at a power of 90 W. In the investigation, it was determined that the drying time was longer and the color change of the dried product was greater when the power was 90 W. Based on this, it can be stated that the color changes of the product will exhibit less deformation if the desired humidity level is obtained quickly during the drying process using the thin slice microwave drying method. However, this should just be viewed as a suggestion for minimizing color change. Numerous criteria, including color change, drying duration, nutrient content, and shelf life, should be assessed concurrently while determining the drying process.

The feasibility of using a computer-vision (CV) system embedded in a hot-air dryer for non-destructive and real-time monitoring of the drying behaviour of organic apples was investigated in the present study. Apple cylinders were subjected to anti-browning treatments with different dipping solutions (water as control, trehalose (4% w/v) or trehalose + ascorbic acid (4% w/v and 1% w/v)) and dipping pressures (atmospheric, 101.3 kPa and sub-atmospheric pressure, 50 kPa) followed by drying at 60 °C to a final dry basis moisture content of 0.18 g g−1. The CV system was used as an in-line process analytical technology (PAT) tool to capture images reflecting the physico-chemical changes during product drying coupled with in-line mass changes and off-line reference analyses. The spatial and colour changes from the image analysis described well the complex and non-homogenous nature of apple drying. The results of spatial changes allowed successful development of accurate linear prediction models for moisture content as a function of area shrinkage (on scaled variables) with excellent prediction capability (|BIAS

This work has investigated the effect of drying temperature on the crystallite size and lattice strain of NiCoAl-LDH using the Williamson–Hall (W–H) method and tracked the impact of the changes thereof on the electrochemical properties. During the experiments, the drying time was kept unchanged, while the temperature was varied from 70 °C, 80 °C to 90 °C. From the X-ray diffractometer (XRD), Fourier-transform infrared spectroscopy (FTIR), Cyclic voltammetry (CV), and Electrochemical impedance spectroscopy (EIS) results, it was found that the drying temperature had greatly influenced the crystalline structure, the interlamellar domain as well as the electrochemical properties of NiCoAl-LDH. An increment in the crystallite sizes was observed from 4.971 to 12.334 nm as the drying temperature increased from 70 to 80 °C and dropped to 7.681 nm when it reached 90 °C. Similarly, an increase in the specific capacitance was recorded from 1158.26 to 4180.16 Fg−1 at 10 mVs −1 as the drying temperature went up from 70 to 80 °C and dropped to 3775.77 Fg −1 at 10 mVs −1 when the drying temperature increased to 90 °C. Moreover, the sample dried at 80 °C exhibited low internal resistance compared to its counterpart. The best electrochemical performance of the sample dried at 80 °C could be attributed to the larger size of its crystallite. This leads to the conclusion that the electrochemical performance of NiCoAl-LDH could be crystallite size-dependent. Finally, it was proved that the drying temperature (80 °C-12 h) is the best for the drying stage of NiCoAl-LDH.

The drying process is one of the oldest methods used to obtain food products that could be stored for a long time. However, drying is an energy-intensive process. Additionally, convective drying, due to the high temperature used during the process, results in loss in bioactive substances as well as nutritional value. Thus, in this research, apple slices were dried in a combined hot air–infrared air dryer with four different drying strategies and drying kinetics, internal and external mass transfer (Crank and Dincer models), and then the energy parameters were investigated. The first, second, third, and fourth strategies, respectively, include one-stage drying with a hot air (HA) or infrared energy source (IR), one stage but with two sources of hot air and infrared (HA–IR), and then there are two stages of first hot air and then infrared drying (HA+IR) and vice versa (IR+HA). According to the results, the highest effective moisture diffusion coefficient of the two Crank and Dincer models was equal to 1.49 × 10−9 and 1.55 × 10−8 m2/s, obtained in the HA70–IR750, and the lowest effective moisture diffusion coefficient was equal to 1.8 × 10−10 and 2.54 × 10−9 m2/s, obtained in IR250+HA40. The maximum (10.25%) and minimum (3.61%) energy efficiency were in the IR750 and HA55–IR250 methods, respectively. Moreover, the highest drying efficiency (12.71%) and the lowest drying efficiency (4.19%) were obtained in HA70+IR500 and HA40–IR250, respectively. The value of specific energy consumption was 15.42–51.03 (kWh/kg), the diffusion activation energy was 18.43–35.43 (kJ/mol), and the value of the specific moisture extraction rate (SMER) was in the range of 0.019–0.054 (kWh/kg). Compared to the other strategies, the second strategy (HA–IR) was better in terms of drying time and mass transfer, and the third strategy (HA+IR) was more efficient in terms of energy efficiency and drying efficiency. The infrared drying in the first strategy was better than that in the other methods in the other strategies in terms of retention of bioactive compounds.

A drying temperature precision control system was studied to provide technical support for developing and further proving the superiority of the variable-temperature drying process. In this study, an improved neural network (INN) proportional–integral–derivative (PID) controller (INN-PID) was designed. The dynamic performance of the PID, neural network PID (NN-PID) and INN-PID controllers was simulated with unit step signals as an input in MATLAB software. A drying temperature precision control system was set up in an air impingement dryer, and the drying temperature control experiment was carried out to verify the performance of the three controllers. Linear variable-temperature (LVT) and constant-temperature drying experiments of cantaloupe slices were carried out based on the system. Moreover, the experimental results were evaluated comprehensively with the brightness (L value), colour difference (ΔE), vitamin C content, chewiness, drying time and energy consumption (EC) as evaluation indexes. The simulation results show that the INN-PID controller outperforms the other two controllers in terms of control accuracy and regulation time. In the drying temperature control experiment at 50 °C–55 °C, the peak time of the INN-PID controller is 237.37 s, the regulation time is 134.91 s and the maximum overshoot is 4.74%. The INN-PID controller can quickly and effectively regulate the temperature of the inner chamber of the air impingement dryer. Compared with constant-temperature drying, LVT is a more effective drying mode as it ensures the quality of the material and reduces the drying time and EC. The drying temperature precision control system based on the INN-PID controller meets the temperature control requirements of the variable-temperature drying process. This system provides practical and effective technical support for the variable-temperature drying process and lays the foundation for further research. The LVT drying experiments of cantaloupe slices also show that variable-temperature drying is a better process than constant-temperature drying and is worthy of further study to be applied in production.

The quality of traditional sunlight-dried orange black tea can be affected by weather variations, leading to its quality instability. This study investigated the feasibility of replacing sunlight drying with a new hot-air drying method in orange black tea production. The hot-air-dried orange black tea showed better sensory quality than the traditional outdoor-sunlight-dried tea, with a harmonious fruity aroma and sweet–mellow taste. The content of polyphenols and other quality components in the peel and tea leaves was significantly higher after hot-air drying than after sunlight drying. GC-MS analysis showed that the total number of volatile components of hot-air-dried tea (3103.46 μg/g) was higher than that of sunlight-dried tea (3019.19 μg/g). Compared with sunlight-dried orange black tea, the hot-air-dried orange black tea showed higher total antioxidant capacity, with an increase of 21.5% (FRAP), 7.5% (DPPH), and 17.4% (ABTS), as well as an increase of 38.1% and 36.3% in the inhibitory capacity on α-glucosidase and α-amylase activities. Further analysis of the effects of different drying temperatures (40, 45, 50, and 60 °C) on the quality of orange black tea showed that the tea quality gradually decreased with the increase in drying temperature, with the most obvious decrease in the quality of orange black tea at the drying temperature of 60 °C. Low-temperature (40 °C) dried tea had better aroma coordination, higher fruit flavor, greater sweet–mellow taste, and higher retention of functional active substances in orange peel and black tea. In summary, compared with traditional sunlight drying, the hot-air drying method could reduce the drying time from 90 h to 20 h and improve the sensory quality and functional activity of orange black tea, suggesting it can replace the traditional sunlight drying process. This work is significant for improving the quality of orange black tea in practical production.

The drying of human whole blood pools has been studied experimentally to improve the understanding of drops and pools of human whole blood. Here blood is assimilated to a complex fluid made of several bio-colloids. The blood pools were created inside a glove box under controlled conditions. We performed experiments at temperatures of 21 °C, 29 °C, and 37 °C, and relative humidity ranging from 20 % to 70 %. The air inside the glove box was still, and the evaporation process was mainly purely diffusive. A human blood diffusion coefficient of (1.08 ± 0.02) × 10 −9 m 2 /s was obtained. This value is in agreement with literature values for polymers and colloidal films. Moreover, we elaborated an updated model using Page's model to describe the drying kinetics of human blood pools. The effect of the surface area of pools was considered using a diffusive characteristics time. These findings are of interest for biomedical and forensic applications.

The dried ammonium polyvanadate (APV) can be used to produce high-purity Vanadium pentoxide (V₂O₅) by calcination. Therefore, drying is a necessary process. The advantages of microwave drying are uniform heating, selective heating, high heating efficiency and the operation process is clean and hygienic. This study uses a microwave to dry APV and discusses the effect of the initial mass, microwave power, initial moisture content on the drying efficiency of APV. The results display that the average drying rate is positively correlated with the microwave output power. When the initial mass is 35 g, the average rate is shown as 0.000263%/s. As the initial moisture content and power of APV increases to 25% and 560W, the average drying rate increases to 0.00036231%/s and 0.003125%/s, respectively. At the same time, through the analysis of APV drying kinetics and the fitting of experimental data, it is found that the APV microwave drying process can be precisely described by the Modified Page model. The microwave heating process saves energy and time, directly penetrates the product, and has certain advantages in green metallurgy.

Porous particles composed of 2,2,6,6-tetramethylpiperidinyl-1-oxyl-oxidized cellulose nanofiber (TOCN) as building block, i.e., porous TOCN particles, are attracting attention due to their environmental friendliness, superior properties, such as easy handling, large surface area, and high adsorption capacity. However, the instability of TOCNs in aqueous environments limits their applications. An effective solution to improve water resistance of TOCN particles is to reduce the hydrophilicity of TOCNs by forming chemical bonds with a cross-linker. In this study, Carbodilite, a common, easy-to-use, commercially available cross-linker with carbodiimide groups, was used to investigate a chemical cross-linking strategy for porous TOCN particles prepared by spray drying. The water resistance of cross-linked TOCN particles was evaluated through morphological observation by SEM images. The presence of polycarbodiimide significantly increased water resistance of cross-linked TOCN particles up to 24 h. This study demonstrates the trade-off between water resistance and adsorption efficiency according to cross-linker concentrations. These data are useful for interface science of TOCNs in liquids, assisting in controlling specific properties of porous TOCN particles for particular applications in adsorption and separation.

The main goal of the investigation was to measure and estimate the thermal stability of pinosylvin, pinosylvin monomethyl ether, robinetin, and dihydrorobinetin, i.e., characteristic compounds of wood of Scots pine and black locust, respectively. The pure compounds were analyzed with chromatography before and after they were steam-sterilized and oven-dried. Detailed thermogravimetric analysis was followed to check the thermal decomposition of the stilbenes and flavonoids of wood. The tested phenolic compounds were susceptible to thermal degradation. After the steam-sterilization and oven drying, the amount of investigated phenolic extractives decreased by more than a half. The thermogravimetric analysis showed that stilbenes decompose differently than flavonoids, which can be attributed to the different chemical structures. Twenty minutes of steam sterilization followed by 24 h of oven drying decreased the amount of phenolic compounds in the vials; however, after the applied thermal treatments, the stilbenes and robinetins stayed available in such quantities that they can still provide sufficient bioactivity. Nasl. z nasl. zaslona. Opis vira z dne 28. 9. 2022. Bibliografija: str. 9-12. Abstract.

Colloidosomes as Pickering emulsion microcapsules are expected to serve various applications, including encapsulation of drugs and loading of functional materials. Normally, when using colloidosomes for drug encapsulation, the latex particles as shell materials need to be mixed with drugs before the assembly process. However, this procedure may cause aggregation of latex particles, thereby resulting in disordered assembled shells or a low loading efficiency. Herein, we propose a three-fluid nozzle spray drying process to efficiently assemble latex particles of P(styrene (St)

Protecting metal surfaces with organic coatings is one of the most common ways of corrosion protection. The main goal of coating is to insulate the base of the material from the corrosive environment in order to provide long lasting protection. The aim of this research is to show how different coating applications in combination with different drying methods affect the coating surface topography. Two different two-component primers were also observed, one containing zinc in its chemical composition and the other one not, to see if zinc had any effect on the surface topography. The surface topography of coatings is examined by the atomic force microscope. At the nano level, the surface condition is quantitatively described by areal topography parameters, also known as 3D roughness parameters. An accelerated laboratory test in the salt spray chamber was performed to compare topography parameters and evaluate which coating system had the slightest differences in observed parameters before and after exposure to a corrosive environment. All the results were statistically processed and presented.

One of the major challenges of the food industry is to develop more sustainable processing technologies. To address this change, it is necessary to have more information about available innovative technologies and their effect on different food matrices and processes to ensure efficiency in food chain management. The aim of this research was to increase the understanding of the physical modifications induced by the combination of pulsed electric field (PEF) pre-treatment and further drying in carrot and potato tissues by modelling the sorption isotherms and the textural properties. High coefficient of determination up to 0.980 for GAB and 0.977 for BET were obtained confirming the good ability of both models to describe the sorption isotherm of foodstuff. Either BET and GAB classified carrot in a III type shape and potato in II type shape for sorption isotherm. Mechanical properties for carrot and potato considering all PEF treatment and aw levels were reported and fitted by modified Fermi distribution. High coefficient of determination up to 0.995 confirm the ability of Fermi model to describe mechanical properties in relation to water activity (aw).

The influence of various drying characteristics in the experiment was explored in this study. The drying time and moisture content were used to evaluate the experimental outcomes. The drying of bitter gourd slices using a halogen dryer was done at varied thicknesses (3, 5, and 7 mm) and temperatures (60 °C, 65 °C and 70 °C). The results revealed that the drying time and equilibrium moisture content are considerably affected by the material drying thickness and drying temperature. Furthermore, the Generalized Regression Neural Network (GRNN) model is employed in this study to train and predict the moisture content of bitter gourd as an output parameter. The temperature, bitter gourd thickness, and drying time were considered as input parameters for the GRNN model. Three statistic measures as the R-square, the Root mean square error (RMSE) and the Mean relative percent error (P) were used to validate the accuracy of the trained GRNN model. In training with nine experimental condition datasets, the average score values of R-square, RMSE and P were obtained at 0.995197, 1.498966 and 0.091617, respectively. The test of trained GRNN has been conducted with good agreement between experimental data points and predicted points. The result revealed that GRNN was effective in predicting the moisture content of bitter gourd in a halogen dryer.

Drying chicken manure with exhaust air from a chicken house is a new manure management method developed in recent years. The majority of the heat for this drying method comes from the waste heat of ventilation in a poultry house or ambient air, so the drying process is carried out at a low temperature. When met with continuous rain or when the wet curtain in the chicken house is turned on, the relative humidity of the exhaust air from the chicken house will rise to high levels, and the drying process will be under the condition of high relative humidity. In order to explore the low-temperature drying characteristics of chicken manure in a humid environment, drying experiments were carried out in an experimental cross-flow drying system. The experiment mainly studied the effect of process parameters such as drying temperature, air velocity, and manure layer thickness on the low-temperature drying characteristics of chicken manure in a humid environment. The results showed that the low-temperature drying process of chicken manure in a humid environment only had a falling rate period, with no accelerated or constant rate period. Additionally, five common thin-layer drying models (Lewis model, Page model, Henderson and Pabis model, Wang and Singh model, and Exponential model) were applied to simulate the performance of the manure drying process. The exponential model was considered to be more suitable for describing the low temperature drying process in a humid environment, and the effective diffusivity changed between 6.37 × 10−7 and 2.17 × 10−6 m2/h.

Recovering waste from industrial food processes and developing new healthy foods as plant protein sources has been a major focus of scientific research and industrial innovation in food. Thus, the consumption of plant-based beverages from soy, oat, or almond has been promoted. In the case of almonds, the resulting solid bagasse has an interesting nutritional profile and its transformation into a powdered product could be a valuable option for the food industry. The main objective of this work was to determine the effect of hot air drying at 60 and 70 °C and freeze-drying on the physicochemical, water interaction, emulsifying and antioxidant properties of powdered almond bagasse. Furthermore, hot air-drying curves have been modelled and isotherms at 20 °C have been performed. The proximate composition of the powder revealed a protein content of 15% and a fat content of 25%, which makes it a remarkably different powder from those obtained from other vegetable residues such as fruits and vegetables. This composition was decisive in the effect of the drying method and drying temperature, and no significant differences were observed on the physico-chemical or antioxidant properties regardless of the drying method used. However, freeze-drying resulted in a powder with a more homogeneous particle size distribution and better oil-interaction properties, especially with higher emulsifying activity and stability.

Mannans are polysaccharides whose physicochemical and biological properties render them commercialization in several products. Since these properties are strongly dependent on production conditions, the present study aims to assess the impact of different drying technologies – freeze (FDM) and spray drying (SDM) – on the structural, physicochemical, and biological properties of mannans from Saccharomyces cerevisiae. Structural analysis was assessed by FT-IR, PXRD and SEM, whereas physicochemical properties were evaluated based on sugars, protein, ash and water contents, solubility, and molecular weight distribution. Thermal behaviour was analysed by DSC, and antioxidant activity by DPPH and ABTS assays. The parameters which revealed major differences, in terms of structural and physicochemical properties regarded morphology (SEM), physical appearance (colour), moisture (3.6 ± 0.1 % and 11.9 ± 0.6% for FDM and SDM, respectively) and solubility (1 mg/mL for FDM and 25 mg/mL for SDM). Nevertheless, these differences were not translated into the antioxidant capacity.

Fresh banana peels can be converted into bioproducts, biofuels and bioenergy. However, the high moisture content of the peel causes its deterioration and limits efficiencies of thermochemical processes for biofuels and bioenergy production. Hence, the microwave drying characteristics of banana peel was investigated. Banana peel slices were dried in a microwave oven at 200-1000 W and the effective moisture diffusivity, activation energy as well as drying energy requirement were determined. Thin layer drying mathematical and artificial neural network models were fitted to the drying data to describe the drying kinetics. The drying rate and effective moisture diffusivity increased while the energy required for drying decreased with increasing microwave power. The drying occurred mainly in the falling rate period. The effective moisture diffusivities were 1.26 x 10-9 – 1.83 x 10-8 m2 s-1 at 200 – 1000 W. The activation energy was 129 Wg-1 while the total and specific energies required for the microwave drying were 0.17 - 0.37 kWh and 48.2 – 107.5 kWh/kg water removed, respectively. The Weibull mathematical model and an artificial neural network model, which had a single-hidden layer network with 3 neurons in the hidden-layer, well described the microwave drying kinetics of the banana peel biomass.

Fresh banana peels can be converted into bioproducts, biofuels and bioenergy. However, the high moisture content of the peel causes its deterioration and limits efficiencies of thermochemical processes for biofuels and bioenergy production. Hence, the microwave drying characteristics of banana peel was investigated. Banana peel slices were dried in a microwave oven at 200-1000 W and the effective moisture diffusivity, activation energy as well as drying energy requirement were determined. Thin layer drying mathematical and artificial neural network models were fitted to the drying data to describe the drying kinetics. The drying rate and effective moisture diffusivity increased while the energy required for drying decreased with increasing microwave power. The drying occurred mainly in the falling rate period. The effective moisture diffusivities were 1.26 x 10-9 – 1.83 x 10-8 m2 s-1 at 200 – 1000 W. The activation energy was 129 Wg-1 while the total and specific energies required for the microwave drying were 0.17 - 0.37 kWh and 48.2 – 107.5 kWh/kg water removed, respectively. The Weibull mathematical model and an artificial neural network model, which had a single-hidden layer network with 3 neurons in the hidden-layer, well described the microwave drying kinetics of the banana peel biomass.

Kaolin clay is one of the essential components of utility and technical ceramic products. Drying is one of the stages of its production and is crucial for the quality of the obtained products. Due to the low energy efficiency of the dryers, it is also one of the most energy-intensive operations performed not only in the production of ceramics but in the industry as a whole. For this reason, modern drying techniques are sought. They are required to be energy efficient, sustainable and produce high-quality products. An example is the so-called hybrid drying, which combines several drying techniques (energy sources) into one process. The aim of this work was to determine the impact of microwave and infrared radiation on the kinetics and energy consumption of convective drying of kaolin clay and the quality of the products. The interaction of convective, microwave and infrared drying was investigated. Drying times, energy consumption and visual quality were compared for the tested processes. The fastest process was convection–microwave drying, where a reduction in drying time of 70% and energy consumption of 50% was observed. Unfortunately, intensive drying had a negative impact on the quality of the products (numerous cracks on the side surface). The best drying methods are those that use all energy sources simultaneously and periodically. Hybrid processes that use all energy sources in a periodic manner had the greatest efficiency. The drying time in these programs was shortened in relation solely to the convection process by 45 to 50% while reducing energy consumption by 3–18%. The product had the best quality.

The aim of this study was to evaluate the effect of spray-drying parameters on the physicochemical properties of encapsulated sea buckthorn berry oil. Different carriers (gum arabic, β-cyclodextrin, and their mixture (1:1, w/w)), inlet air temperatures (120, 150, and 180 °C), and carrier-to-oil ratios (2, 3, and 4, w/w) were evaluated. The obtained powders were characterized in terms of the product yield (36.79–64.60%), encapsulation efficiency (73.08–93.18%), moisture content (0.23–3.70%), hygroscopicity (1.5–7.06 g/100 g), solubility (19.55–74.70%), bulk density (0.25–0.44 g/L), total carotenoid content (mg/100 g dm), and antioxidant capacity (871.83–1454.39 μmol TE/100 g dm). All physicochemical properties were significantly affected by the carrier-to-oil ratio and inlet air temperature. Higher carrier-to-oil ratios increased the product yield, encapsulation efficiency, solubility, and bulk density and decreased the powder hygroscopicity. Elevating the drying temperatures during spray drying also increased the product yield, encapsulation efficiency, and solubility, while it decreased the powder moisture content, total carotenoid content, and antioxidant capacity. Based on the physicochemical properties, the use of β-cyclodextrin as a carrier, a drying temperature of 120 °C, and a carrier-to-oil ratio of 4 were selected as optimal conditions for the production of sea buckthorn berry oil powder. The obtained powder is a valuable material for a wide range of applications in the food and nutraceutical industries.

In this paper, the effects of different ultrasonic pretreatment processes on the far-infrared drying characteristics, quality indexes, and microstructure of licorice are evaluated. The results showed that ultrasonic pretreatment, combined with far-infrared drying, significantly reduced the drying time and moisture content of licorice compared with those of the control group. The highest total flavonoid content was obtained at an ultrasound power of 80 W. The total phenolic content (0.686 mg gallic acid equivalent/g) was higher than that in the control group, the increase was 19.4%, and its content was the highest at the sonication frequency of 20 kHz. The antioxidant capacity tended to increase and then decrease with the increase in sonication time, sonication power, and sonication frequency, and was the highest at 30 min of sonication. The soluble sugar content (31.490 mg glucose equivalent/g) was the highest at 30 kHz and 30 min. Observation of the microstructure revealed that the surface structure of the ultrasonic pretreated licorice slices changed significantly, forming more micropore channels, which facilitated the mass heat transfer during the drying process. In conclusion, ultrasonic pretreatment can significantly improve the quality of licorice tablets and significantly reduce the time required for subsequent drying. The combination of pretreatment parameters of 60 W ultrasonic power and 40 kHz ultrasonic frequency for 30 min was found to be an optimal combination of pretreatment parameters; therefore, this study may provide a technical reference for the industrialization of licorice drying.

Lavandula angustifolia Mill. is a part of the Lamiaceae family, which includes aromatic plants used in perfumery, manufactory, food, ornamental, and medicinal sectors. Both fresh and dried lavender flowers can be exploited in different ways; however, post-harvest treatments such as drying processes can help maintain the flowers’ properties for a longer period. This study analyzed fresh (F) and dried lavender flower ultrasound-assisted extracts, comparing two different drying methods, i.e., heat-pump drying (HP) and hot-air drying (HA), to assess potential differences in their effect on the phytochemical composition (total phenolic content, total anthocyanin content, and phenolic profile) and antioxidant activity (FRAP, DPPH, and ABTS assays) of flowers, focusing on three lavender selections from north-western Alps (i.e., Susa, Stura, and Tanaro). Results showed that HP-dried flowers are to be preferred over HA-dried flowers, as they contain +66.73% of phenolics and +62.2% of anthocyanins, and they have higher antioxidant activity (from 60.32% to 284.3% more according to the assay). HP-dried flowers, particularly those from the Tanaro selection, showed also higher values in the relative antioxidant capacity index (RACI) and the global antioxidant score (GAS), ranking together with the fresh flowers. Nine bioactive compounds out of thirteen were detected by means of HPLC, seven in F (caffeic acid, hyperoside, quercetin, ellagic acid, catechin, epicatechin, and dehydroascorbic acid), four in HA (ferulic acid, hyperoside, quercitrin, and epicatechin), and two in HP (caffeic acid and hyperoside). The higher temperatures used in HA probably promoted oxidative and biochemical reactions that led to the presence and increase in these compounds. However, many other phenolic compounds may contribute to the antioxidant power of lavender extracts. Overall, HP resulted in an effective and sustainable method for drying lavender flowers and may have interesting applications to obtain final products richer in bioactive compounds and antioxidant activity to be used in the functional food industry.

Mangosteen pericarps (MP) often end up as agricultural waste despite being rich in powerful natural antioxidants such as anthocyanins and xanthones. This study compared the effect of different drying processes and times on phenolic compounds and antioxidant activities of MP. Fresh MP were subjected to 36 and 48 h of freeze-drying (−44 ± 1 °C) and oven-drying (45 ± 1 °C), and 30 and 40 h of sun-drying (31 ± 3 °C). The samples were analyzed for anthocyanins composition, total phenolic content (TPC), total flavonoid content (TFC), antioxidant activities, and color characteristics. Analysis of liquid chromatography-mass spectrometry (LC-MS) with electrospray ionization identified two anthocyanins in MP: cyanidin-3-O-sophoroside and cyanidin-3-O-glucoside. Overall, the drying process, time, and their interactions significantly (p < 0.05) influenced the phenolic compounds, antioxidant activities, and color in MP extracts. Both freeze-drying after 36 h (FD36) and 48 h (FD48) possessed significantly (p < 0.05) higher total anthocyanins (2.1–2.2 mg/g) than other samples. However, FD36 was associated with significantly (p < 0.05) higher TPC (~94.05 mg GAE/g), TFC (~621.00 mg CE/g), and reducing power (~1154.50 μmol TE/g) compared to FD48. Moreover, FD36 is more efficient for industrial applications due to less time and energy consumption. Subsequently, obtained dried MP extracts could be further utilized as an alternative to synthetic food colorants.

Background: Apple cider vinegar (ACV) contains many health benefits due to its antioxidant and acetic acid content. However, the adverse effects of directly consuming the vinegar should be eliminated to make it possible to regulate its intake as a dietary supplement. The objective of the study is to optimize the spray drying operating conditions to produce ACV powder with health benefits. A central composite design (CCD) of response surface methodology (RSM) was used to optimize the spray drying process of ACV. The influences of inlet temperature (130°C–170°C), gum Arabic concentration (5%–15% w/w), and feed flow rate (1–2 kg/h) on some product and process aspects were investigated. Spray-dried powders were evaluated for their moisture content, process yield, acetic acid content, solubility, and antioxidant content.Results: The relationships between the model factors and final powder properties were established with ANOVA and multiple regression analysis. The model factors affected the investigated powder properties at different significance levels, where carrier concentration was the main influencing factor. Gum Arabic contributed to the retention of volatile and heat-sensitive compounds providing health benefits. All powders showed high solubility (>94%) and high antioxidant recovery, and most treatments achieved a drying yield of higher than 50%.Conclusion: Optimization of spray drying process was achieved with application of RSM and relationships between model factors and powder properties were established. This study highlighted the feasibility of the development of ACV-based functional powder as a dietary supplement.

In this study, coriander leaves were subjected to three different drying techniques; direct sun, shade, and using an indirect solar dryer. In the developed dryer, hot air obtained from a black-body solar collector was pushed by a blower powered by a solar panel, and sent to the drying chamber with multiple trays for thin-layer drying. Experiments were conducted for summer and winter seasons, and temperature and relative humidity variations in the drying chamber were measured using a data acquisition system. Indirect solar dryer performance was evaluated and compared with sun drying and shade drying for drying kinetics, moisture diffusivity, and product quality. The drying rate curves show a linear falling rate throughout the drying process. The drying kinetic models are well-fitted with the Midilli and Kucuk thin-layer drying model. The effective moisture diffusivity of the dried coriander shows a decreasing trend, sun drying (2.63 × 10−10 m2/s and 1.05 × 10−10 m2/s) followed by solar dryer (1.31 × 10−10 m2/s and 6.57 × 10−10 m2/s), and shade drying (6.57 × 10−11 m2/s and 3.94 × 10−11 m2/s) for winter and summer seasons, respectively. Green color changes from −7.22 to −0.056, −7.22 to 3.15, and −7.22 to −0.35 in indirect solar, direct sun, and shade drying, respectively. The hue angle and Chroma are reduced by 12% and 32% in indirect solar drying, respectively. The total phenol content (TPC) value increases with drying, with summer showing the highest values (365 to 852 mg caffeic acid/100 g dry weight) while the antioxidant capacity reaches 3.41 and 3.53 in winter and summer, respectively from 0.22 μmol Trolox/g dry matter of fresh leaves.

Large amounts of waste result from licorice mold rot; moreover, prompt drying directly influences product quality and value. This study compared various glycyrrhiza drying methods (Hot air drying (HAD), infrared combined hot air drying (IR-HAD), vacuum freeze drying (VFD), microwave vacuum drying (MVD), and vacuum pulsation drying (VPD)) that are used in the processing of traditional Chinese medicine. To investigate the effects of various drying methods on the drying characteristics and internal quality of licorice slices, their color, browning, total phenol, total flavonoid, and active components (liquiritin and glycyrrhizic acid) were chosen as qualitative and quantitative evaluation indices. Our results revealed that VFD had the longest drying time, but it could effectively maintain the contents of total phenol, total flavonoid, and liquiritin and glycyrrhizic acid. The results also showed that VFD samples had the best color and the lowest degree of browning, followed by HAD, IR-HAD, and VPD. We think that VFD is the best approach to ensure that licorice is dry.

The effects of drying temperature and air velocity on the drying characteristics, color, bioactive compounds, rehydration ratio, and microstructure of Ophiopogonis Radix during hot air impingement drying (HAID) were explored in the current study. The experimental results showed that the drying temperature and air velocity had a significant impact on the drying characteristics and quality attributes of dried products except for the rehydration ratio. The drying time decreased from 720 to 240 min with the increase of drying temperature from 50 to 70 °C. Increasing the air velocity from 6 to 12 m/s enhanced the drying process of Ophiopogonis Radix, while the extension of air velocity to 15 m/s lowered the drying rate. The samples that were dried at a lower drying temperature obtained lower color difference. Properly increasing the drying temperature or air velocity could increase the total polysaccharide and flavonoid contents of dried products. Additionally, a back-propagation neural network (BPNN) model was developed to predict the moisture ratio of Ophiopogonis Radix during the drying process. The optimal BPNN with 3-11-1 topology were obtained to predict the moisture ratio of Ophiopogonis Radix during HAID and performed with an acceptable performance.

Drying is one of the methods used for preserving fruits and vegetables. However, due to the lengthy process and elevated temperature of convective drying, other pretreatment and drying methods are studied to shorten the drying time and obtain high-quality products. This study aimed to examine the effect of ultrasonic (US) pretreatment and microwave–hot air drying (MW–HA) on the drying time, specific energy (SEC), qualitative properties (e.g., color, shrinkage, and rehydration ratio), and bioactive compound properties (e.g., antioxidant activity, phenolic, and flavonoid contents) of hawthorn fruit. Experiments were performed using ultrasound pretreatment and a microwave dryer (microwave power: 180, 360, and 540 W) at air temperatures of 40, 55, and 70 °C. Drying of hawthorn lasts from 35 min for the ultrasound-treated sample (dried at 540 W and 70 °C) to 180 min (dried at 180 W and 40 °C without US treatment). The lowest amount of SEC (24.11 MJ/kg) was obtained using the US–MW–HA air drying method (dried at 540 W and 70 °C). The lowest values in total color change (13.37) and shrinkage (22.47%) were recorded for the sample dried with a MW power of 360 W and air temperature at 55 °C with US pretreatment prior to drying. Generally, the use of US and MW–HA air drying reduces the antioxidant activity (AC), total phenolic content (TPC), and total flavonoid content (TFC) during processing compared to fresh samples. The highest values for AA (28.01%), TPC (69.44 mg GAE/g d.m.), and TFC (64.38 mg QE/g) obtained at 360 W and 55 °C with US pretreatment for hawthorn fruit dried.

This work aimed to establish an integrated approach to investigate the total phenolic content and antioxidant activities of dried skim camel and cow milk and their fractions. The milk fractions were obtained by acid or enzymatic coagulation followed by spray drying (inlet temperature/outlet temperature: 125 ± 2 °C/90 ± 2 °C) or freeze drying (−50 °C, 0.05 mbar) coupled or not to gamma irradiation (at 5, 11, 22 kGy). The results showed that the total phenolic content (measured in gallic acid equivalent, GAE) varied depending on the drying technique. The freeze-drying process corresponded to the highest values of total phenolic compounds, with 247.23 ± 2.08 mg GAE/100 g powder for the β-casein fraction of camel milk (βC CaM) and 621.13 ± 4.16 mg GAE/100 g powder for the β-casein fraction of cow milk (βC CoM). Compared to spray-dried fractions, freeze-dried fractions showed generally higher ferric reducing antioxidant power for both camel milk and cow milk. The highest values of free radical scavenging activity were seen in the spray-dried β-casein fractions of camel milk (βC CaM) and cow milk (βC CoM) and in the freeze-dried acid whey of cow and camel milk (AW CaM and AW CaM). Freeze-dried acid whey (AW CaM and AW CoM) appeared to be less sensitive to gamma irradiation at 5 and 11 kGy.

In order to improve the shortcomings of uneven heating of traditional microwave drying and to maximally maintain food quality after harvest, a rotary microwave vacuum drying equipment was fabricated and used for drying experiments on Angelica sinensis to explore the effects of drying temperature, slice thickness, and vacuum degree on drying characteristics, physicochemical quality, and microstructure of dried Angelica sinensis products. The results showed that microwave vacuum drying can significantly shorten the drying time and improved the drying efficiency. Six different mathematical models were investigated and the Midilli model was the best-fitted model for all samples (R2 = 0.99903, Pearson’s r = 0.99952), and drying methods had various effects on different indexes and were confirmed by Pearson’s correlation analysis and principal component analysis. The optimal process parameters for microwave vacuum drying of Angelica sinensis were determined by entropy weight-coefficient of variation method as 45 °C, 4 mm, −0.70 kPa. Under this condition, well preserved of ferulic acid, senkyunolide I, senkyunolide H, ligustilide, total phenols and antioxidant activity, bright color (L* = 77.97 ± 1.89, ΔE = 6.77 ± 2.01), complete internal organizational structure and more regular cell arrangement were obtained in the samples. This study will provide a theoretical reference for the excavation of the potential value and the development of industrial processing of Angelica sinensis.

Mulberry fruits (MF) contain many biologically active compounds beneficial for human health. In particular, in the literature, there are no studies on the kinetics of the freeze-drying of MF and the effect of the process temperature on the properties of dried fruits. The objective of this study was to ascertain how freeze-drying (FD) and air-drying temperature affected the kinetics of dehydration and chosen physicochemical parameters of MF. Both temperature and dehydration methods significantly influenced the drying rate and properties of MF. The Midilli model was the best fitted to the experimental data of the course of drying curves and with the lowest values of mean-square error. The highest lightness and yellowness were noted for freeze-dried fruit, whereas air-dried MF were characterized by the highest redness. An increase in drying temperature significantly changed the color of fruits and led to the degradation of L-ascorbic acid content. The highest content of L-ascorbic acid was found in fresh fruits (214 ± 4 mg/100 g dry mass (DM)) and freeze-dried fruits at 30 °C (182 ± 3 mg/100 g DM). Both FD and AD drying significantly reduced the content of this compound. The lowest reduction in L-ascorbic acid was observed for freeze-dried fruits. Fruits freeze-dried at 30 °C showed the highest content of total phenolics and antioxidant capacity.

The present study aimed to investigate the effect of different microwave pre-drying times under hot-air-drying processes on the quality properties and sensory evaluation of Sipunculus nudus (S. nudus). The colour, proximate analysis, amino acid content, fat oxidation, and volatile components of dried S. nudus were determined. Microwave pre-drying could significantly (p < 0.05) increase the drying rate and shorten the drying time. The results of colour, proximate analysis, and amino acid content indicated that microwave pre-drying could improve the quality of the product, resulting in dried S. nudus with less of a loss in nutrients. The samples that underwent microwave pre-drying had a high degree of fatty acid oxidation and low monounsaturated fatty acid content, which facilitated the formation of volatile components. Additionally, the MAD-2 and MAD-3 groups had high relative contents of aldehydes and hydrocarbons, and the FD group had the highest relative content of esters found in the samples. The relative content of ketones and alcohols did not differ significantly between the different drying groups. The finding of this study has important potential for enhancing the quality and aroma of dry S. nudus products with microwave pre-drying during the drying process.