Effect of ultrasonic pretreatment on drying kinetics and physio‐mechanical characteristics of peach slices

Enhanced Bioactive Coffee Cherry: Infusion of Submerged-Fermented Green Coffee Beans via Vacuum Impregnation

Submerged fermentation offers a controlled environment for coffee processing, ensuring a consistent temperature and aerobic-anaerobic conditions, making it a superior alternative to solid-state fermentation. This study aimed to optimize submerged fermentation conditions for green coffee beans to maximize total phenolic content (TPC) and antioxidant activity, such as ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), DPPH (2,2-Diphenyl-1-picrylhydrazyl), and FRAP (the ferric reducing antioxidant power). Additionally, pH, yeast, and lactic acid bacteria counts were monitored. Fermentation was conducted with selective microbial starters, a varying temperature (25-35 °C), incubation time (3-9 days), and coffee weight (5-10 g) using a Box-Behnken design. To enhance bioactive compound infusion, fresh coffee cherries underwent ultrasonic treatment, increasing their porosity and water-holding capacity. Vacuum impregnation was then used to infuse fermented green coffee bean extract into the cherries. The lowest pH coincided with peak yeast growth, while the coffee weight significantly influenced all responses. The incubation time affected most parameters except DPPH activity, and the temperature impacted only ABTS and DPPH activities. Optimal conditions (35 °C; 7.21 days; 10 g) yielded a TPC of 480.25 µmol GAE/100 g with ABTS, DPPH, and FRAP activities of 725.71, 164.15 and 443.60 µmol TE/g, respectively. Ultrasound-treated coffee cherries exhibited increased porosity and absorption capacity, facilitating enhanced bioactive compound infusion during 3 h of vacuum impregnation. In conclusion, submerged fermentation effectively improves bioactive compound production, while ultrasound treatment and vacuum impregnation present promising methods for developing high-value dehydrated coffee cherry products.

A novel hybrid MCDM framework combining TOPSIS, PROMETHEE II, and VIKOR for peach drying method selection

The selection of optimal drying technologies for peach processing presents a complex decision-making challenge due to multiple conflicting criteria. This study introduces a novel hybrid multi-criteria decision-making (MCDM) framework combining TOPSIS, VIKOR, and PROMETHEE II methods to evaluate eight drying technologies. The evaluation was conducted across twelve criteria, encompassing product quality, operational efficiency, economic factors, and environmental impact. Data were collected from five industry experts through structured matrices. The results demonstrate that vacuum drying emerged as the optimal technology, maintaining the top position in 75 % of sensitivity scenarios. Freeze drying and heat pump drying consistently ranked among the top three alternatives across all methods. The correlation analysis revealed strong agreement between VIKOR and PROMETHEE II rankings (0.857), while TOPSIS provided complementary insights. Sensitivity analysis identified energy consumption, investment cost, and nutritional retention as the most critical factors influencing technology selection. The findings indicate that advanced drying technologies significantly outperform traditional methods in terms of overall performance. This research provides a comprehensive framework for evidence-based decision-making in food processing technology selection and establishes quantitative benchmarks for future technology evaluations in the fruit drying industry.

Developing Effective Radio Frequency Vacuum Drying Processes for Moutan Cortex: Effect on Moisture Migration, Drying Kinetics, Physicochemical Quality, and Microstructure

This study aims to maximize the post-harvest quality of Moutan Cortex and reduce energy consumption. Radio frequency vacuum (RFV) technology was used to dehydrate Moutan Cortex in this study to investigate the effects of different drying temperatures, plate spacing, and vacuum degree on the drying kinetics, physicochemical quality, and microstructure of Moutan Cortex. The results showed that RFV drying shortened the dehydration time of the Moutan Cortex by 10.71-28.57% and increased the drying rate by 15.79-54.39% compared to hot-air drying. The best color (∆E = 6.08 ± 0.28, BI = 26.97 ± 0.98) and relatively high retention of polysaccharides, total phenolics, total flavonoids, antioxidant properties, paeonol, gallic acid, paeoniflorin, and benzoylpaeoniflorin contents were observed in the dried products of Moutan Cortex at a drying temperature of 50 °C, spacing of 90 mm, and vacuum of 0.025 MPa. Analyzing the microstructure, it was found that RFV drying could effectively inhibit the shrinkage and collapse of the cellular structure, and a regular and loose honeycomb pore structure appeared inside the samples, which contributed to the rapid migration of the internal moisture. This study can provide a theoretical reference basis for the selection and application of industrialized processing methods of high-quality Moutan Cortex.

Drying kinetic, thermodynamic and quality analyses of infrared drying of truffle slices

Kinetic and thermodynamic parameters are the most important part for making a suitable tool for drying agricultural products. Moreover, calculation of the energy required for the drying of product, the properties of the rehydration ratio, the food appearance changes, and the evaluation of the microstructure of food are crucial. Since the thermodynamic properties of truffle slices have not yet been reported, this study aims to establish a mathematical model to describe drying process of agriculture product, evaluate the effective moisture diffusion coefficient (Deff), determining the activation energy (Ea) to elucidate the thermodynamic characteristics, measure color characteristics, and rehydration ratio (RR) during the drying process of truffle slices. Truffle slices were dried in an infrared (IR) dryer at four temperatures of 50-80°C and two thicknesses of 0.5 and 1 cm. The best model to describe the drying process of truffle slices was Midilli et al.'s model. The value of Deff, SEC, and RR were in the range of 3.06 × 10-8 to 2.48 × 10-7 m2/s, 79.68-191.271 kWh/kg, and 5.99-7.49, respectively. The Deff of truffle slices increased with the above-mentioned parameters of the samples. The Ea obtained was 26.62-27.43 kJ/mol. The results indicated that enthalpy and entropy decreased with increasing drying temperature, while Gibbs free energy improved. The enthalpy, entropy, and Gibbs free energy values changed between 24.48-25.28 kJ/mol, -130.47 to -122.63 J/mol °K, and 63.97-70.17 kJ/mol, respectively. In addition, the results of color attributes decreased with increasing temperature, while chroma oppositely increased.

Influence of ultrasound pretreatment on drying characteristics of cocoyam (Xanthosoma sagittifolium) slices during convective hot air drying

BACKGROUND

Convective hot air drying of cocoyam is risk-free and inexpensive to a significant level. However, hot air drying causes negative changes to the color, texture, flavor and nutritional content of cocoyam as a result of the prolonged drying. Recently, the innovative technology of ultrasound pretreatment has been applied in food processing to reduce the processing time, conserve energy and preserve the quality of the food product. Thus, there is need to investigate the effect of ultrasound pretreatment with distilled water (UDW) and ultrasound with osmotic dehydration (UOD) for different ultrasonic times (10-30 min) on the drying kinetics of cocoyam slices during convective hot air drying. Ultrasound pretreatment was applied at a frequency of 20 kHz and an output power of 600 W for UDW and UOD. The ultrasound-pretreated samples were further dried in a convective hot-air drying oven at 70 °C.

RESULTS

UDW and UOD samples, respectively, had a 25% and 46% reduction in drying time compared to untreated samples. The UOD samples had the lowest activation energy (10.697 × 10 3 kJ), as well as the highest moisture diffusivity (3.782  × 10-10  m2  s-1 ) and mass transfer coefficient (2.006  × 10-8  m s-1 ), among the untreated and UDW samples. Wang and Singh, Page and Peleg models were found to be the most fitted models with respect to the drying characteristics of cocoyam for untreated, UDW and UOD samples, respectively.

CONCLUSION

Ultrasound pretreatment technology is a potential non-thermal process that can be incorporated as a pretreatment method in the convective drying of cocoyam to reduce processing time, conserve energy and enhance cocoyam product shelf life. © 2023 Society of Chemical Industry.

Effects of gum-based coatings combined with ultrasonic pretreatment before drying on quality of sour cherries

Application of pretreatment methods such as ultrasound and edible coatings is used to reduce processing time and/or preserve food product quality in drying technology. The aim of this research was to measure the impacts of gum-based coatings (guar, sodium alginate, and basil seed gums) in combination with sonication before drying on total phenolic content (TPC), antioxidant capacity (AC), effective water diffusivity (Deff), total color difference (ΔE), surface shrinkage (SS), and rehydration ratio (RR) of sour cherries. Ultrasonic pretreatment (40 kHz, 150 W, at 25 °C, for 12 min) increased the TPC, AC, Deff, and RR, and decreased the drying time, ΔE, and SS values of sour cherries. Edible coating increased the TPC, AC, drying time, and RR, and decreased the Deff, ΔE, and SS values of sonicated sour cherries. The TPC for untreated, uncoated-sonicated, guar gum-coated, sodium alginate-coated, and basil seed gum-coated sour cherries were 2965.9, 3398.1, 3480.8, 3511.0, and 3898.3 Âµg gallic acid equivalent/g dry, respectively. The highest value of AC (71.2±3.7 %) was observed on coated sour cherries by basil seed gum. The experimental data for drying curves were fitted to several widely used models, and the Midilli model using the experimental constants that best represent the drying rate of sour cherries. The edible coatings significantly reduced the color changes and shrinkage of dried sour cherries, with the lowest ΔE and SS values in the basil seed gum-coated samples (p < 0.05).

Mass transfer kinetics (soluble solids gain and water loss) of ultrasound-assisted osmotic dehydration of apple slices

Ultrasound (sonication) treatment can be used directly for dehydration or pre-treatment before the osmotic dehydration (OD) procedure of fruit or vegetable particles. The combination of this technique with the OD technique can further improve the dehydration process efficiencies by increasing the mass transfer rates and enhancing final product quality. In this study, apple slices were osmotically dehydrated in different hypertonic sucrose solutions and assisted with or without ultrasound. Sucrose concentrations (in three levels of 30, 40, and 50° Brix), sonication power (in three levels of 0, 75, and 150 W), and treatment time (in six time intervals: 10, 20, 30, 40, 50, and 60 min) were the factors investigated concerning weight reduction, soluble solids gain, water loss and rehydration. Also, mass transfer kinetics were modelled according to Page, Newton, Midilli, Logarithmic, Verma, and Two terms equations. Increased sucrose solution concentration resulted in higher weight reduction, soluble solids gain and water loss. Also, increased sonication power levels resulted in higher weight reduction, soluble solids gain and water loss. The average rehydration ratio of apple slices decreased from 237.7 to 177.5%, by increasing osmotic solution concentration from 30 to 50%. The Page equation showed the best fitting for water loss data. The effective moisture diffusivity (D_eff) of apple slices during OD calculated using Fick’s second law applied to a slab geometry was found to be in the range of 1.48 × 10^–10 and 4.62 × 10^–10 m²s⁻¹ for water loss.