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

Enhancing drying characteristics and quality of fruits and vegetables using biochemical drying improvers: A comprehensive review

Traditional drying is a highly energy-intensive process, accounting for approximately 15% of total manufacturing cost, it often resulting in reduced product quality due to low drying efficiency. Biological and chemical agents, referred to as biochemical drying improvers, are employed as pretreatments to enhance both drying characteristics and quality attributes of fruits and vegetables. This article provides a thorough examination of various biochemical drying improvers (including enzymes, microorganisms, edible film coatings, ethanol, organic acids, hyperosmotic solutions, ethyl oleate alkaline solutions, sulfites, cold plasma, carbon dioxide, ozone, inorganic alkaline agents, and inorganic salts) and their effects on improving the drying processes of fruits and vegetables. Additionally, it introduces physical drying improvers (including ultrasonic, pulsed electric field, vacuum, and others) to enhance the effects of biochemical drying improvers. Pretreatment with biochemical agents not only significantly enhances drying characteristics but also preserves or enhances the color, texture, and bioactive compound content of the dried products. Meanwhile, physical drying improvers reduce moisture diffusion resistance through physical modifications of the food materials, thus complementing biochemical drying improvers. This integrated approach mitigates the energy consumption and quality degradation typically associated with traditional drying methods. Overall, this review examines the role of biochemical agents in enhancing the drying characteristics and quality of fruits and vegetables, offering a comprehensive strategy for energy conservation and quality improvement.

Effect of (multi pin) atmospheric cold plasma treatment on curcumin extraction and investigating phytochemicals, antioxidants, physical and morphological properties of turmeric (Curcuma longa L.) powder

This investigation was focused on the impact of cold plasma (CP) on the extraction of curcumin and bioactive compounds of turmeric powder (TP). TP was treated with CP at different applied voltages (10, 20, and 30 kV), with various exposure times (10, 20, and 30 min). The curcumin content was highest at 30 kV for 10 min with a yield of 46.49 mg/g of TP. Total phenols significantly (p < 0.05) enhanced from 163.91 to 360.78 mg GAE/g DW accompanied by a remarkable 16% increment in total flavonoids, paralleled by a 26% increment in antioxidants as of control. Nuclear magnetic resonance spectra justified the extraction of curcuminoids. Moreover, micrographs displayed cell lysis in the treated powder. CP has exhibited a positive effect on surface colour parameters and thermal properties of TP. Overall, CP technology can be tailored for better curcumin extraction and the enhancement of phytochemicals.

Effect of ultrasound combined with chemical pretreatment as an innovative non-thermal technology on the drying process, quality properties and texture of cherry subjected to radio frequency vacuum drying

To obtain high-quality cherry products, ultrasound (US) combined with five chemical pretreatment techniques were used on cherry prior to radio frequency vacuum drying (RFV), including carboxymethyl cellulose coating (CMC), cellulase (CE), ethanol (EA), isomaltooligosaccharide (IMO), and potassium carbonate + ethyl oleate (PC + AEEO). The effect of different pretreatments (US-CMC, US-CE, US-EA, US-IMO, US-(PC + AEEO)) on the drying characteristics, quality properties, texture, and sensory evaluation of cherries was evaluated. Results showed that the dehydration time and energy consumption were decreased by 4.17 - 20.83 % and 3.22 - 19.34 %, respectively, and the contents of individual sugars, soluble solid, total phenolics (TPC), natural active substances, total flavonoids (TFC), and antioxidant properties (DPPH, ABTS and FRAP) were significantly increased after US combined with five chemical treatments (P < 0.05). Moreover, the pretreatment played important role in improving texture properties and surface color retention in the dried cherries. According to the sensory evaluation analysis, the dehydrated cherries pretreated with US-CMC exhibited the highest overall acceptance, texture, crispness, color, and sweet taste showed lower off-odor, bitter taste and sour taste compared to control and other pretreatments. The findings indicate that US-CMC pretreatment is a promising technique for increasing physicochemical qualities and dehydration rate of samples, which provides a novel strategy to processing of dried cherry.

Incorporation of ascorbic acid in chitosan-based coating combined with plasma-activated water: A technology for quality preservation of red grapes after simulated transportation

Red grapes possess multiple bioactivities but are highly susceptible to spoilage due to the lack of efficient preservation techniques. Plasma-activated water (PAW) treatment and the incorporation of antioxidants in bio-based coatings are promising methods for preserving produce. In this study, we tested a novel combination by incorporating ascorbic acid (AA) into a chitosan-based edible coating (CH) and combining it with plasma-activated water (PAW) treatment (CA-PAW) before simulating transport vibrations to extend the shelf-life of red grapes. The results from storage at 4 °C for 20 d indicated that the CA-PAW treatment reduced microbial counts by 2.62 log10 CFU/g for bacteria, 1.72 log10 CFU/g for yeasts and molds, and 1.1 log10 CFU/g for coliforms, in comparison to the control group treated with sterile deionized water. Total phenols and total flavonoid content were the highest observed, at 111.2 mg GAE/100 g and 262.67 mg RE/100 g, respectively. This treatment also inhibited water migration and erosion, and reduced damage to cell structure. Microstructural observations revealed that the CH coating on the surface of red grapes diminished the degradation of bioactive components. In conclusion, the CA-PAW treatment effectively inhibited the adverse physiological changes caused by vibration and mechanical damage to red grapes, maintained their nutritional and sensory qualities, and extended the shelf life by at least 8 d.

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).

Effect of Biopolymer Dip-Coating Pretreatments as a Non-Thermal Green Technology on Physicochemical Characteristics, Drying, and Rehydration Kinetics of Santa Maria Pears

This research was conducted to determine the influences of biopolymer dip-coating pretreatments as a non-thermal green technology on the drying behavior, retention of bioactive compounds, and quality properties of pears. The fresh pears were washed, peeled, and diced into cubes of 5 × 5 mm with a 2 mm thickness and were dipped into 0.3% (w/v) solutions of sodium alginate (SA), pectin (PC), xanthan gum (XG), Arabic gum (AG), and gelatin (GE) before hot air drying (70 °C, 2.0 m/s). The weight loss of samples during drying was recorded online, and the moisture ratio (MR) and drying rate were plotted against drying time. Biopolymers significantly decreased the drying time (maximum 33.33% by SA) compared with uncoated samples except for XG. Moisture diffusion coefficients were determined according to Fick's second law of diffusion by plotting LnMR against drying time, and a linear regression analysis was applied to the data for the determination of moisture diffusion coefficients which ranged from 2.332 to 3.256 × 10^-9 m²/s. The molecular transport of momentum, heat, and mass were determined from Newton's law of viscosity, Fourier's law, and Fick's law, respectively. The results indicated that the friction drag force, convective heat, and mass transfer coefficients were 6.104 × 10^-6 N, 76.55 W/m²·K, and 0.0636 m/s, respectively. Mathematical modeling showed the suitability of the Midilli and Kucuk and the Peleg models for the prediction of drying and rehydration processes, respectively. Thermal conductivity, specific heat, and density of coated samples ranged from 0.559-0.579 (W/m·K), 3735-3859 (J/kg·K), and 850.90-883.26 (Kg/m³), respectively. The porosity was reduced due to the penetration of biopolymers into the cellular matrix of samples. The highest total polyphenol content and antioxidant activity belonged to the AG samples. The biopolymers covering the surface of samples produced a protection layer against the loss of bioactive compounds. Biopolymers can be successfully used as a non-thermal green process for improving the drying and quality characteristics of pears at the industrial level.

Factors affecting energy efficiency of microwave drying of foods: an updated understanding

Microwave drying (MWD) is an efficient dielectric drying method in food, with advantages such as volumetric heating, fast drying, safety, and good product quality. As a key indicator of a dryer's market value, energy efficiency is of concern to sellers and dryer manufacturers. This paper systematically reviewed the quantification methods and influencing factors of energy efficiency of microwave drying in food application from different perspectives. Mechanisms and possible improvements of these factors are highlighted. Future trends in improving the energy efficiency of MWD are proposed. Energy consumption of MWD depends on a variety of factors such as equipment structure, drying conditions (microwave power, frequency, temperature, and air velocity), material properties, and combined/hybrid drying technologies. The drying system can be effectively improved if these parameters are adjusted appropriately and taking the processing cost into consideration. Although a good product can be obtained by pretreatment or combined/hybrid drying method, it may consume more energy. Future research should develop artificial intelligence, renewable energy, and computational fluid dynamics technology to pave the way for large-scale application of MWD and reduce energy consumption.