Infrared assisted hot air dryer for turmeric slices:Effect on drying rate and quality parameters

Artificial intelligence as a tool for predicting the quality attributes of garlic (Allium sativum L.) slices during continuous infrared-assisted hot air drying

Effective drying methods are a highly suitable solution for ensuring stable food supply chains, reducing postharvest agricultural losses, and preventing the spoilage of perishable fruits and vegetables. Moreover, machine learning techniques are innovative and dependable, especially in addressing food spoilage and optimizing drying processes. This study utilized a continuous infrared (IR) hot air dryer to dry garlic (Allium sativum L.) slices. The experiments were conducted at different levels of IR power, air velocities (V), and temperature (T). The relationships between the input process parameters (IR, T, and V) and response parameters, including effective moisture diffusivity (Deff), drying time, and physicochemical properties of the dried slices (rehydration ratio [RR], total color change, flavor strength, and allicin content in the garlic), were modeled using an artificial neural network (ANN). Our findings showed that the maximum Deff of 6.8 × 10-10 m2/s and minimum drying time of 225 min were achieved with an IR of 3000 W/m2, an air velocity of 0.7 m/s, and a temperature of 60°C. The total color change and RR values increased with IR and higher air temperature but declined with higher air velocity. Furthermore, the garlic's flavor strength and allicin content levels decreased as the IR and air temperature increased. The results demonstrated a significant influence of the independent parameters on the response parameters (p < 0.01). Interestingly, the ANN predictions closely matched the test data sets, providing valuable insights for understanding and controlling the factors affecting drying behaviors.

Segmented variable-frequency ultrasound synergistic hot-air drying of Rhubarb: Effect on drying characteristics and quality and thermal analysis

This study employed segmented variable-frequency ultrasound synergistic hot-air drying (SVFU-HAD) for Rhubarb slices, selected two sets of time nodes for frequency conversion (60 min, 120 min, and 90 min, 150 min), and two sequences of frequency conversion (high-frequency to low-frequency, and low-frequency to high-frequency). It aimed to investigate the effects of SVFU-HAD on the drying characteristics, quality, and heat transfer of Rhubarb slices. The findings indicated that segmented variable-frequency ultrasound has advantages in increasing drying rate and improving uniformity of cavitation effects compared to constant-frequency ultrasound. Analysis of physical properties revealed that the rehydration performance of dried products subjected to ultrasonic variable-frequency treatment (90 min, 150 min) according to the drying rate was better (RR > 3.3). The transition mode from high-frequency to low-frequency in variable-frequency ultrasonic treatment contributes to maintaining the overall color of Rhubarb. Analysis of chemical properties unveiled that Rhubarb treated with 40 kHz (0 min)-28 kHz (60 min)-25 kHz (120 min) segmented variable-frequency ultrasound contained overall higher levels of tannins, dianthrones and free anthraquinones content, which exceeded the average values by 3.24%, 26.65%, and 14.42%, respectively. In addition, thermal analysis results based on ANSYS Workbench software demonstrated that the drying uniformity of SVFU-HAD is superior to that of hot-air drying and constant-frequency ultrasound synergistic hot-air drying (CFU-HAD). Overall, the SVFU-HAD method employed in this study presents an innovative approach to ultrasound synergistic hot-air drying research with promising potential for enhancing the efficiency and quality characteristics of Rhubarb slices.

Optimization of Processing Parameters for Continuous Microwave Drying of Crab Apple Slices via Response Surface Methodology

To improve product quality and obtain suitable processing parameters for crab apple slices (CASs) produced by continuous microwave drying (CMD), the effects of processing parameters, including slice thickness, microwave power, air velocity, and conveyor belt speed, on the evaluation indexes in terms of temperature, moisture content, color (L*, a*, b*), hardness, brittleness, and total phenolic content of CASs were investigated via the response surface method. The results indicated that microwave power has the greatest effect on the evaluation indexes applied to the CASs under CMD, followed by air velocity, slice thickness, and conveyor belt speed. To produce the desired product quality, the appropriate parameters for CMD of CASs were optimized as 1.25 mm slice thickness, 14,630 W microwave power, 0.50 m·s-1 air velocity, and 0.33 m·min-1 conveyor belt speed. Following that, the moisture content under CMD was found to be 13.53%, the desired color, hardness 0.79 g, brittleness 12.97 (number of peaks), and the total phenolic content 5.48 mg·g-1. This research provides a theoretical framework for optimizing the processing parameters of CASs using the response surface method.

Implementation of fuzzy logic control algorithm for temperature control in robusta rotary dryer coffee bean dryer

BACKGROUND

Indonesia is one of the coffee producers ranked third in the world in the supply of coffee beans. To maintain competitiveness international market, it is necessary to maintain and improve the quality of coffee beans.

OBJECTIVE

One crucial aspect of maintaining the quality of coffee beans is maintaining the moisture content of green coffee beans. One of the water content settings is using the drying method. While traditional drying methods often experience weather and long-time constraints.

RESULTS

This study designed an innovative coffee bean dryer based on fuzzy logic to overcome the problem. This system uses temperature control with Mamdani's fuzzy logic control interference algorithm, input and delta errors, and output percentage valve opening. This method achieved a moisture content following SNI standards of 12% and a 0.00015% / s drying rate for each coffee bean mass increased by 1kg. This method is also more efficient and stable in maintaining the temperature at a value of 50°C.

METHODS

The drying equipment also estimates the drying time by considering variations in the mass of coffee beans. This dryer can provide an effective solution to maintain optimal coffee bean quality.

CONCLUSION

The second semi-wash method of drying coffee beans using a fuzzy logic-based coffee bean drier has proven successful for drying coffee beans to a moisture content of 12% in a period of 90 min to 195.65 min with a drying capacity of 1 kilogram to 10kg at 50°C.•The coffee beans utilized in the studies are robusta coffee beans from plantations on Mount Kawi's slopes in East Java, Indonesia.•The trial sample was 1 kilogram of green coffee beans removed from the horn skin.•According to SNI standards, the drying performed is the second in the postharvest semi-wash procedure to achieve a moisture content of 12%.

Influences of emerging drying technologies on rice quality

Rice is an important staple food in the world. Drying is an important step in the post-harvest handling of rice and can influence rice qualities and thus play a key role in determining rice commercial and nutritional value. In rice processing, traditional drying methods may lead to longer drying times, greater energy consumption, and unintended quality losses. Thus, it is imperative to improve the physical, chemical, and milling properties of rice while preserving its nutritional value, flavor, and appearance as much as possible. Additionally, it is necessary to increase the efficiency with which heat energy is utilized during the thermal processing of freshly harvested paddy. Moreover, this review provides insights into the current application status of six different innovative drying technologies such as radio frequency (RF) drying, microwave (MW) drying, infrared (IR) drying, vacuum drying (VD), superheated steam (SHS) drying, fluidized bed (FB) drying along with their effect on the quality of rice such as color, flavor, crack ratio, microstructure and morphology, bioactive components and antioxidant activity as well asstarch content and glycemic index. Dielectric methods of drying due to volumetric heating results in enhanced drying rate, improved heating uniformity, reduced crack ratio, increased head rice yield and better maintain taste value of paddy grains. These novel emerging drying techniques increased the interactions between hydrated proteins and swollen starch granules, resulting in enhanced viscosity of rice flour and promoted starch gelatinization and enhanced antioxidant activity which is helpful to produce functional rice. Moreover, this review not only highlights the existing challenges posed by these innovative thermal technologies but also presents potential solutions. Additionally, the combination of these technologies to optimize operating conditions can further boost their effectiveness in enhancing the drying process. Nevertheless, future studies are essential to gain a deeper understanding of the mechanism of quality changes induced by emerging processing technologies. This knowledge will help expand the application of these techniques in the rice processing industry.

Preserving nutrient content in red cabbage juice powder via foam-mat hybrid microwave drying: Application in fortified functional pancakes

Red cabbage, a highly nutritious cool-season cruciferous vegetable, is rich in anthocyanins; however, the instability of anthocyanins during processing and storage poses challenges. This study aimed to optimize the foam-mat drying process of red cabbage juice (RCJ) with a high anthocyanin content using a hybrid microwave hot air-drying system (MW-HAD) as a dehydration method compared to conventional techniques (HAD) using response surface methodology (RSM). Additionally, the produced red cabbage juice powder (RCJP) was used to enrich the pancake formulation. The developed model exhibited a high degree of reliability with optimal conditions and was determined for microwave power, temperature, foaming agent carboxymethylcellulose (CMC), and egg white protein (EWP) as 360 W, 60°C, 0.3%, and 1.2%, respectively. Moisture content (%) was decreased from 93.47 to 8.62 at optimum process conditions. In comparison to the control (60°C), foam mat drying with the MW-HAD hybrid system reduced the drying time (DT) by more than 90.9% due to the higher drying rate, while many physicochemical properties, especially total anthocyanin content (TAC), were better preserved. Utilization of RCJP in the production of anthocyanin-rich functional pancakes resulted in enhanced nutritional qualities compared to control pancakes with increased protein (35.07%), total phenolic (75.8%), dietary fiber (82.9%), and anthocyanin content (100%). In conclusion, MW-HAD demonstrates significant potential as a promising drying method to reduce the DT and preserve the physicochemical properties of RCJP. Furthermore, the application of the optimized RCJP in anthocyanin-rich functional pancakes highlights improved nutritional qualities, making a substantial contribution to the advancement of functional foods.

Heat source replacement strategy using catalytic infrared: A future for energy saving drying of fruits and vegetables

Drying is an important process for fruits and vegetables, which requires a lot of heat and the heat sources are mainly coal, electricity, natural gas, and solar energy. Most of the heat is usually wasted due to the long drying process and poor transfer efficiency. The use of coal also pollutes the environment. The national electricity curtailment policy regulates the drying industry. Therefore, the fruits and vegetables drying industry is facing new challenges due to its own development needs and external factors. Catalytic infrared drying (CIR) technology brings solutions to these problems. Compared with other drying technologies, CIR has a high drying efficiency and can effectively reduce the use of electric energy, avoid waste, and minimize pollution of water. However, improper processing conditions still cause quality deficits such as severe browning, and the drying is difficult due to weak infrared penetration. Although CIR has shortcomings, it is still expected to establish an energy-saving and efficient fruit and vegetable drying system.

Effects of thermal and salt water soaking pre-treatment on the physicochemical and nutritional properties of sundried tilapia fish (Oreocromis niloticus) products

The effects of saltwater soaking (10-30 %, w/v) and thermal (60°C-90 °C) pre-treatment on the physicochemical and nutritional quality of sundried tilapia fish (Oreocromis niloticus) products were assessed. The wet reduction was 14.47 % in the sample treated with a 30 % salt solution at 90 °C, whereas the wet reduction of 21.23 % was observed in the sample without treatment (control). Protein, lipid, and ash content were increased significantly (P < 0.05) with higher pre-treatment salt concentration and temperature, while the moisture content showed the opposite trend. The content of essential and non-essential amino acids in the treated samples ranged from 7149.97 mg/100 g to 8063.42 mg/100 g and 10530.66 mg/100 g to 11365.59 mg/100 g, respectively, whereas the values were 7018.55 mg/100 g and 10400.84 mg/100 g, respectively in the control. The fatty acids composition, particularly ω-3 polyunsaturated fatty acids, was higher in pretreated samples (6.14-7.08 %) compared to the control. Mineral content was found to improve with saltwater and thermal pre-treatment, and the levels of heavy metals, including Ni and Cu, were significantly lower in the sundried tilapia fish. The sample pretreated with 10 % salt solution and 75 °C showed the highest rehydration capacity of 66.63 %. These findings suggest that saltwater and thermal pre-treatment can effectively enhance the physicochemical and nutritional properties of sundried tilapia fish products.

Qualitative, energy and environmental aspects of microwave drying of pre-treated apple slices

In the present research, response parameters such as specific energy consumption (SEC), thermal efficiency (TE), energy efficiency (EF), drying time (DT), greenhouse gas (GHG) emission (such as CO2 and NOx), and quality features (color variation and shrinkage) were modeled by response surface methodology (RSM) for apple slices dried in a microwave dryer under ultrasonication (30 ℃-10 min) and blanching (80 °C-2 min) pretreatments. Also, RSM was applied to optimize two independent parameters including microwave power and sample thickness in the levels 100, 200, and 300 W and 2, 4, and 6 mm, respectively. The results indicated the significant influence (P < 0.01) of the independent parameters on the response parameters. The vales of SEC, DT, GHG emission, shrinkage, and color difference were linearly decreased with the declining sample thickness and increasing microwave power, while the energy and thermal efficiencies were increased by a quadratic equation. The use of ultrasonication and blanching pretreatments decreased the SEC, GHG emissions, and DT; while improving the quality of the samples as compared to the non-treated slices. The optimization results showed the optimal drying times (31.55, 82.19, and 50.55 min), SEC (3.42, 10.07, and 4.37 MJ/kg), CO2 with natural gas (1539.75, 1518.75, and 4585 g), CO2 with gas oil (3662.53, 2099.25, 2721.25 g), NOx with natural gas (10.094, 9.956, and 12.906 g), and NOx with gas oil (12.934, 12.758, and 16.538 g) at a microwave power of 300 W and sample thickness of 2 mm with desirability of 0.921, 0.935, and 0.916 for control samples, ultrasonicated, and blanched, respectively.

Effect of Combined Infrared Hot Air Drying on Yam Slices: Drying Kinetics, Energy Consumption, Microstructure, and Nutrient Composition

Using hot air drying (HAD) and combined infrared hot air drying (IR-HAD) test devices, the drying kinetics, unit energy consumption, color difference values, rehydration rate, microstructure, and changes in polysaccharide and allantoin contents of yam slices were examined at various temperatures (50 °C, 55 °C, 60 °C, 65 °C, and 70 °C). The findings demonstrated that each of the aforementioned parameters was significantly impacted by the drying temperature. IR-HAD dries quicker and takes less time to dry than HAD. The Deff of IR-HAD is higher than that of HAD at the same temperature and increases with the increase in temperature. The activation energy required for IR-HAD (26.35 kJ/mol) is lower than that required for HAD (32.53 kJ/mol). HAD uses more energy per unit than IR-HAD by a factor of greater than 1.3. Yam slices treated with IR-HAD had higher microscopic porosity, better rehydration, lower color difference values, and higher polysaccharide and allantoin levels than HAD-treated yam slices. The IR-HAD at 60 °C had the greatest comprehensive rating after a thorough analysis of the dried yam slices using the coefficient of variation method. Three statistical indicators were used to evaluate six thin-layer drying models, and the Weibull model was most applicable to describe the variation of drying characteristics of yam slices.

Rehydration modeling and characterization of dehydrated sweet corn

The increasing demand of rehydrated foods is due to its better storage stability at ambient conditions and not requiring refrigeration. Prior to drying at 55, 60, 65, and 70°C in a hot air tray dryer, hot water blanching (HB), steam blanching (SB), and microwave blanching (MB) were employed as pretreatments. Rehydration of dried pretreated sweet corn kernel was performed in boiling water. The pretreatments and drying temperatures were independent factors that affected the dependent factors such as rehydration ratio, total sugar, ascorbic acid, geometric mean diameter, color, sensory evaluation, water absorption, mass, and geometric mean diameter. Peleg, Weibull, and newly proposed models were considered to describe the change in moisture content during rehydration. The proposed model performed better than other models and indicated the rise in equilibrium moisture content of rehydrated sweet corn with an increase in dehydration temperature of sweet corn due to higher R 2 (0.994), and lower chi-square (0.005) and RMSE (0.064). The rehydrated sweet corn obtained from samples processed with microwave blanching and dehydration at 70°C showed higher retention of total sugar, ascorbic acid, geometric mean diameter, and color.

Microwave assisted fluidized bed drying of bitter gourd: Modelling and optimization of process conditions based on bioactive components

Bitter gourds were dried under varied drying conditions in a microwave assisted fluidized bed dryer, and the process was optimized using response surface methodology. Microwave power, temperature and air velocity were used as process variables for drying and the process parameters were varied between 360 and 720 W, 40-60 °C and 10-14 m/s, respectively. The responses determined for deciding the optimal criteria were vitamin C, total phenolics, IC₅₀, total chlorophyll content, vitamin A content, rehydration ratio, hardness and total color change of the dried bitter gourd. Statistical analyses were done by using response surface methodology, which showed that independent variables affected the responses to a varied extent. The optimum drying conditions of 550.89 W microwave power, 55.87 °C temperature, and 13.52 m/s air velocity were established for microwave assisted fluidized bed drying to obtain highest desirability for the dried bitter gourd. At optimum conditions, validation experiment was done to ensure the suitability of models. Temperature and drying time plays an important role in the deterioration of bioactive components. Faster and shorter heating led to the greater retention of bioactive components. Taking the aforesaid results into consideration, our study recommended MAFBD as a promising technique with minimum changes in quality attributes of bitter gourd.

Individual and interactive effect of ultrasound pre-treatment on drying kinetics and biochemical qualities of food: A critical review

One of the earliest and most prevalent processing methods to increase the shelf-life of foods is drying. In recent years, there has been an increased demand to improve product quality while lowering processing times, expenses, and energy usage in the drying process. Pre-treatments are therefore effectively used before drying to enhance heat and mass transfer, increase drying efficiency, and lessen degradation of final product quality. When food is dried, changes are expected in its taste, color, texture, and physical, chemical, and microbial properties. This has led to the need for research and development into the creation of new and effective pre-treatment technologies including high-pressure processing, pulsed electric field, ultraviolet irradiation, and ultrasound. Sound waves that have a frequency >20 kHz, which is above the upper limit of the audible frequency range, are referred to as "ultrasound". Ultrasonication (US) is a non-thermal technology, that has mechanical, cavitational, and sponge effects on food materials. Ultrasound pre-treatment enhances the drying characteristics by producing microchannels in the food tissue, facilitating internal moisture diffusion in the finished product, and lowering the barrier to water migration. The goal of ultrasound pre-treatment is to save processing time, conserve energy, and enhance the quality, safety, and shelf-life of food products. This study presents a comprehensive overview of the fundamentals of ultrasound, its mechanism, and how the individual effects of ultrasonic pre-treatment and the interactive effects of ultrasound-assisted technologies affect the drying kinetics, bioactive components, color, textural, and sensory qualities of food. The difficulties that can arise when using ultrasound technology as a drying pretreatment approach, such as inadequate management of heat, the employment of ultrasound at a limited frequency, and the generation of free radicals, have also been explained.

Prediction of Apple Slices Drying Kinetic during Infrared-Assisted-Hot Air Drying by Deep Neural Networks

The effects of temperature, air velocity, and infrared radiation distances on the drying characteristics and quality of apple slices were investigated using infrared-assisted-hot air drying (IRAHAD). Drying temperature and air velocity had remarkable effects on the drying kinetics, color, total phenol content, total flavonoid content, and vitamin C content (VCC) of apple slices. Infrared radiation distance demonstrated similar results, other than for VCC and color. The shortest drying time was obtained at 70 °C, air velocity of 3 m/s and infrared radiation distance of 10 cm. A deep neural network (DNN) was developed, based on 4526 groups of apple slice drying data, and was applied to predict changes in moisture ratio (MR) and dry basis moisture content (DBMC) of apple slices during drying. DNN predicted that the coefficient of determination (R2) was 0.9975 and 1.0000, and the mean absolute error (MAE) was 0.001100 and 0.000127, for MR and DBMC, respectively. Furthermore, DNN obtained the highest R2 and lowest MAE values when compared with multilayer perceptron (MLP) and support vector regression (SVR). Therefore, DNN can provide new ideas for the rapid detection of apple moisture and guide apple processing in order to improve quality and intelligent control in the drying process.

Novel sequential and simultaneous infrared-accelerated drying technologies for the food industry: Principles, applications and challenges

Infrared drying (IRD) is considered an innovative drying solution for the food industry with advantages of energy-saving potentials, reduced drying time and production cost-effectiveness. However, IRD also suffers from drawbacks such as weak penetrative ability, and product overheating and burning. Therefore, over the years, significant progress has been made to overcome these shortcomings by developing infrared-accelerated drying (IRAD) technology based on the combination of IRD with other drying technologies. Although several reviews have been published on IRD, no review focusing on IRAD is yet available. The current review presents up-to-date knowledge and findings on the applications of IRAD technologies for enhancing the quality and safety of food. The fundamental principles and characteristics of IRAD, energy-saving potentials, simulation and optimization approaches for enhancing efficiency, and developments in various acceleration approaches by combining with other drying techniques for achieving better end-products are discussed, and challenges and future work for developing the novel accelerated drying technology are also presented. Due to the synergistic effects of sequential or simultaneous combined drying methods, the total drying time and energy required are drastically lowered with most IRAD technologies, and consequently there are significant improvements in the sensory, nutritional, and safety attributes of dried food products with better appearance and quality. The development of multi-wavelength IRAD systems based on infrared absorption bands, and the incorporation of novel sensing techniques for real-time monitoring during drying will further enhance process efficiency and food quality and safety.

Mathematical Description of Changes of Dried Apple Characteristics during Their Rehydration

The mathematical description of changes of dried apples characteristics (mass gain, volume increase, dry matter loss, rehydration indices, and colour) during their rehydration was performed. The effect of conditions of both processes on model parameters were also considered. Apple slices (3 and 10 mm) and cubes (10 mm) were dried in natural convection (drying air velocity 0.01 m/s), forced convection (0.5 and 2 m/s), and fluidisation (6 m/s). Drying air temperatures (Td) were equal to 50, 60, and 70 °C. The rehydration process was carried out in distilled water at the temperatures (Tr) of 20, 45, 70, and 95 °C. Mass gain, volume increase, and dry matter loss were modelled using the following empirical models: Peleg, Pilosof–Boquet–Batholomai, Singh and Kulshrestha, Lewis (Newton), Henderson–Pabis, Page, and modified Page. Colour changes were described through applying the first-order model. Artificial neural networks (feedforward multilayer perceptron) were applied to make the rehydration indices and colour variations (ΔE) dependent on characteristic dimension, Td, drying air velocity, and Tr. The Page and the modified Page models can be considered to be the most appropriate in order to characterise the mass gain (RMSE = 0.0143–0.0619) and the volume increase (RMSE = 0.0142–0.1130), whereas the Peleg, Pilosof–Bouquet–Batholomai, and Singh and Kulshrestha models were found to be the most appropriate to characterise dry matter loss (RMSE = 0.0116–0.0454). The ANNs described rehydration indices and ΔE satisfactorily (RMSE = 0.0567–0.0802). Both considered process conditions influenced (although in different degree) the changes of the considered dried apple characteristics during their rehydration.

Effects of infrared heating as an emerging thermal technology on physicochemical properties of foods

Infrared (IR) radiation is part of an electromagnetic spectrum between the ultraviolet and microwave regions. IR radiation impacts the surface of the food, generating heat that can be used as an efficient drying technique. Apart from drying, IR heating is an emerging food processing technology with applications in baking, roasting, microbial inactivation, insect control, extraction for antioxidant recovery, peeling, and blanching. Physicochemical properties such as texture, color, hardness, total phenols, and antioxidants capability of foods are essential quality attributes that affect the food quality. In this regard, the main objective of this review study was to highlight and discuss the effects of IR heating on food quality to expand its food applications and commercial adoption. The fundamental mechanisms, type of emitters, and IR processing parameters are discussed in this review to explore their impacts on food quality. Infrared heating has been shown that the appropriate operating conditions (distance, exposure time, IR power, and temperature) with high heat transfer, thus leading to a shorter drying time. Besides, IR heating used in food processing to improve food-surface color and flavor, it also enhances hardness, firmness, shrinkage, crispiness, and viscosity. Meanwhile, antioxidant activity is enhanced, and some nutrients are retained.

Application of Artificial Neural Networks, Support Vector, Adaptive Neuro-Fuzzy Inference Systems for the Moisture Ratio of Parboiled Hulls

Drying as an effective method for preservation of crop products is affected by various conditions and to obtain optimum drying conditions it is needed to be evaluated using modeling techniques. In this study, an adaptive neuro-fuzzy inference system (ANFIS), artificial neural network (ANN), and support vector regression (SVR) was used for modeling the infrared-hot air (IR-HA) drying kinetics of parboiled hull. The ANFIS, ANN, and SVR were fed with 3 inputs of drying time (0–80 min), drying temperature (40, 50, and 60 °C), and two levels of IR power (0.32 and 0.49 W/cm2) for the prediction of moisture ratio (MR). After applying different models, several performance prediction indices, i.e., correlation coefficient (R2), mean square error index (MSE), and mean absolute error (MAE) were examined to select the best prediction and evaluation model. The results disclosed that higher inlet air temperature and IR power reduced the drying time. MSE values for the ANN, ANFIS tests, and SVR training were 0.0059, 0.0036, and 0.0004, respectively. These results indicate the high-performance capacity of machine learning methods and artificial intelligence to predict the MR in the drying process. According to the results obtained from the comparison of the three models, the SVR method showed better performance than the ANN and ANFIS methods due to its higher R2 and lower MSE.

Effects of carboxymethyl cellulose/pectin coating combined with ultrasound pretreatment before drying on quality of turmeric (Curcuma longa L.)

Turmeric is an herb with multiple bioactive substances and health benefits. Drying is one of the most important steps of its processing and sales. In order to obtain high-quality turmeric products, we used five different pretreatment methods to treat turmeric prior to pulse-spouted microwave vacuum drying (PSMVD), including carboxymethyl cellulose coating (CMC), pectin coating (P), ultrasound (US) and their combination (CMCUS or PUS). The effect of different pretreatments on the drying kinetics, quality attributes and microstructure of turmeric were evaluated. Results showed that the US pretreatment had the shortest drying time (60 min), while coating treatment did not significantly affect drying rate. Dried turmeric with coating pretreatment had lower rehydration ratio and water adsorption capacity compared with individual ultrasound treatment. Carboxymethyl cellulose coating protected bioactive substances better than pectin coating. Moreover, CMCUS pretreatment showed significantly lower total color change, higher curcumin content, total phenols and flavonoid content as well as antioxidant capacity in all dried samples. Microstructure observation showed that the polysaccharide coating covering the surface of turmeric might reduce the degradation of bioactive compounds. Therefore, the CMCUS pretreatment before PSMVD of turmeric was recommended due to the efficiency and quality protections.