Project description:Okra (Abelmoschus esculentus) was dried to a moisture level of 0.1 g water/g dry matter using a microwave-assisted hot air dryer. Response surface methodology was used to optimize the drying conditions based on specific energy consumption and quality of dried okra. The drying experiments were performed using a central composite rotatable design for three variables: air temperature (40-70 °C), air velocity (1-2 m/s) and microwave power level (0.5-2.5 W/g). The quality of dried okra was determined in terms of color change, rehydration ratio and hardness of texture. A second-order polynomial model was well fitted to all responses and high R(2) values (>0.8) were observed in all cases. The color change of dried okra was found higher at high microwave power and air temperatures. Rehydration properties were better for okra samples dried at higher microwave power levels. Specific energy consumption decreased with increase in microwave power due to decrease in drying time. The drying conditions of 1.51 m/s air velocity, 52.09 °C air temperature and 2.41 W/g microwave power were found optimum for product quality and minimum energy consumption for microwave-convective drying of okra.
Project description:In order to improve the drying quality of winter jujube slices and find the best drying process parameters, RF + HA (radio frequency combined hot air) drying technology was used in this study to study the effects of plate spacing, RF application time, and RF interval time on the quality of winter jujube slices. Vitamin C (VC) content, red and green value (a*), and drying rate (DR) were used as quality indexes, and the changing trend of texture properties was analyzed. According to the conclusion of the single-factor experiment, the orthogonal experiment is carried out, and the parameters of each factor in the orthogonal experiment are optimized by the comprehensive balance method and matrix analysis method. The results showed as follows: (1) Plate spacing, RF application, and interval time all significantly affected the drying properties in the single-factor test (p < 0.05). The VC content of winter jujube slices increased and then decreased with the increase in the three factors. (2) In the orthogonal test, the order of influence of each factor on the quality of the winter jujube tablet is plate spacing > RF interval time > RF application time. The optimum RF heat treatment parameters are plate spacing of 100 mm, RF application time of 3 min, and RF interval time of 2 min. Under these conditions, the VC content of the winter jujube slices was 258.35 mg/100 g, a* was -9.47 and the DR was 0.64 g/min. (3) RF + HA has more advantages in shortening drying time and maintaining shape, reducing hardness by 12.6 ~ 18.7% and crispiness by 13.8 ~ 20.4%, the microstructure of jujube slices shows a regular honeycomb shape. The research results provide a new drying combination mechanism and process optimization scheme for improving the drying technology of winter jujube slices in industrial production.
Project description:Refractance window drying technology can be used to produce high quality dried fruit products due to its excellent retention of heat sensitive nutrients, organoleptic properties and bioactive compounds. This study optimised conditions for drying of pineapple slices and puree using RWDT. i-optimal design in Design Expert software was used to generate temperature-thickness combinations in form of runs. The independent factors considered included drying temperature (70-90 °C) and thickness (2-3 mm), and the responses included drying time and vitamin C concentration. The optimum solutions generated for RW drying temperature and pulp thickness were 86.2 °C and 2.9 mm for puree and 78.9 °C and 2 mm for slices. The drying times for puree and slices were 58 and 96 min, respectively with corresponding vitamin C content of 64.88 and 46.83 mg/100 g. Drying kinetics of puree and slices were determined at optimal conditions. Drying was found to follow Modified Midilli et al. Model. Pineapple powder obtained using optimal RWD conditions had low water activity (0.41), high solubility (74.64%) and dehydration ratio (4.12). Pineapple reconstituted drinks were developed and evaluated for consumer preference. Acceptability was highest at 15% inclusion of pineapple powder.Supplementary informationThe online version contains supplementary material available at 10.1007/s13197-021-05302-2.
Project description:Apple slices of the Elise variety were previously osmo-dehydrated in erythritol, xylitol, and sucrose for 2 h. In some parts of the experiment, 30 min of ultrasound pre-treatment (US) were applied. Afterwards, fruit samples were dried by convective (CD), microwave-vacuum (VM), and a combined method (CD/VM, mix two of them). The main aim of the research was to characterize an impact of osmotic dehydration, sonication pre-treatment, and drying method on the physicochemical properties of the dried apples. The use of sugar alcohols (xylitol, erythritol) in the production of dried apples did not badly affect the taste of the obtained dried products; it enabled a noticeable cooling/refreshing effect felt in the mouth when consuming a snack, and enabled the production of dried snacks with lower calorific value. Polyol residues in the product were at a level that was safe for consumers. The most popular convective drying was long lasting, whereas the VM drying method allowed for the shortest drying time, amounting to 76 min; moreover, additional application of ultrasounds reduced this time to 36 min. The combined drying method allowed the total duration of the process to be reduced 2-4.5 times. Ultrasound applied during osmotic dehydration did not significantly affect attributes of the descriptive sensory analysis for the obtained dried apples. The best hygroscopic properties, ensuring the storage stability of the dried product, showed dried apples previously osmo-dehydrated in erythritol and sucrose solutions.
Project description:The heat-based spray drying process generating the highest level of advanced glycation end-products (AGEs) in the infant formula processing was set as a control point from which the levels of AGE markers, N-carboxymethyllysine, 5-hydroxymethylfurfural, and fluorescence intensity, can be mitigated. We optimized the parameters, including inlet temperature, feeding rate, and aspirator rate during spray drying, and alternatively optimized food additives, including pyridoxine hydrochloride, dl-α-tocopheryl acetate, and l-carnitine. Using response surface methodology, the optimal condition based on our experimental condition for the inlet temperature, pump rate, and aspirator rate were 148.7 °C, 342.4 mL/h and 28.6 m3/h, respectively, and the optimal conditions of pyridoxine hydrochloride, dl-α-tocopheryl acetate and l-carnitine were 0.99 mg/100 g dry mass (DM), 8 mg/100 g DM and 20.4 mg/100 g DM, respectively. These results suggest that AGEs can be mitigated by controlling the parameters and optimizing the addition of food additives during the spray-drying process.
Project description:Ginger is one of the most popular spices and medical herbs with its unique pungent flavour and taste. Although there has been much research into the drying methods of ginger, the effect of drying parameters in hot air convective drying on ginger quality needs to be explored in depth. This study investigated the differences in drying behaviour and quality characteristics of ginger with the variables of temperature, thickness, and loading density. The moisture states and diffusion pattern in the different stages during the drying process were analysed using low-field NMR techniques. The results of quality evaluation showed that the temperature greatly influenced the colour and gingerol content of dried ginger, and the thickness of a ginger slice greatly influenced the rehydration rate. Optimal drying conditions were determined by considering a combination of specific energy consumptions with quality retention based on the response surface methodology: a temperature of 66.41 °C, thickness of 2 mm, and loading density of 5 kg/m2. HS-GC-IMS combined with multivariate chemometrics was used to achieve the characterisation of flavour profiles and fingerprinting of dried ginger. The principal component analysis and correlation analysis revealed that the alterations in ginger quality were intimately related to moisture diffusion during drying.
Project description:Polyphenols in carobs have recently attracted great attention due to their wide range of biological and health promoting effects. A comprehensive study was conducted to find an optimum method for the extraction, purification and characterization of these valuable bioactive substances. Under this framework, the ultrasound-assisted extraction (UAE) of polyphenols from carob pulp was optimized by the maximization of the yield in total phenolics using response surface methodology. In particular, the effects of solid-solvent ratio, solvent concentration, extraction time, sonication amplitude, and sonication mode were investigated and optimized using a complete experimental design. In comparison to conventional extraction techniques, UAE offered a higher yield of antioxidants and a shorter processing time. Solid-phase extraction was evaluated as a clean-up strategy prior to the electrophoretic analysis of extracts. The results from the analysis of real samples revealed the predominance of gallic acid and highlighted the great influence of the ripening stage on carobs composition.
Project description:The main goal of this study was to investigate the effect of extraction conditions on the enzymatic properties of thermoacidic amylase enzyme derived from dragon peel. The studied extraction variables were the buffer-to-sample (B/S) ratio (1:2 to 1:6, w/w), temperature (-18°C to 25°), mixing time (60 to 180 seconds), and the pH of the buffer (2.0 to 8.0). The results indicate that the enzyme extraction conditions exhibited the least significant (P < 0.05) effect on temperature stability. Conversely, the extraction conditions had the most significant (P < 0.05) effect on the specific activity and pH stability. The results also reveal that the main effect of the B/S ratio, followed by its interaction with the pH of the buffer, was significant (P < 0.05) among most of the response variables studied. The optimum extraction condition caused the amylase to achieve high enzyme activity (648.4 U), specific activity (14.2 U/mg), temperature stability (88.4%), pH stability (85.2%), surfactant agent stability (87.2%), and storage stability (90.3%).
Project description:Phlorizin is a plant-derived molecule with relevant anti-diabetic activity, making this compound a potential functional component in nutraceutical formulations for the management of glycemia. It is noteworthy that promising sources for the extraction of phlorizin include apple tree leaves, a by-product of apple fruit production. The main aim of this study was to optimize the extraction process of phlorizin from Annurca apple tree leaves (AALs) using response surface methodology (RSM), and to determine the potential nutraceutical application of the obtained extract. The results of the RSM analysis indicate a maximum phlorizin yield of 126.89 ± 7.579 (mg/g DW) obtained under the following optimized conditions: MeOH/H2O, 80:20 + 1% HCOOH as the extraction solvent; 37.7 °C as the extraction temperature; and 170 min as the time of extraction. The HPLC-DAD-HESI-MS/MS analysis performed on the extract obtained under such conditions, named optimized Annurca apple leaves extract (OAALE), led to the identification of twenty-three phenolic molecules, with fifteen of them quantified. To explore the nutraceutical potential of OAALE, the in vitro antioxidant activity was evaluated by DPPH, ABTS, and FRAP assays, resulting in 21.17 ± 2.30, 38.85 ± 0.69, and 34.14 ± 3.8 μmol Trolox equivalent/g of extract, respectively. Moreover, the IC50 of 0.330 mg/mL obtained from the advanced glycation end-product inhibition assay, further supported the antidiabetic potential of OAALE.
Project description:This study focused on persimmons and applied variable-temperature pressure-differential puffing drying to produce persimmon chips. The effects of puffing pressure, holding time, drying temperature, and duration on moisture content, crispness, and sensory scores were examined. The optimal parameters determined via response surface methodology were a pressure differential of 0.46 MPa, holding time of 10 min, drying temperature of 94 °C, and drying time of 92 min, achieving a moisture content of 3.63%, crispness of 362.83 g, and sensory score of 90.8. Microstructural and porosity analysis showed that this method predominantly produced chips with large pores and enhanced pore volume (0.2949 cm3/g), porosity (30.16%), and average pore diameter (194.0 nm). Compared to microwave drying, vacuum microwave drying, and vacuum frying, the pore volume of persimmon chips processed using pressure-differential puffing drying increased by 57.7% to 237.8%, the porosity improved by 57.2% to 237.8%, and the average pore diameter grew by 82.2% to 660.8%. Notably, the differences were most pronounced when compared to vacuum frying, with increases of 237.8%, 237.8%, and 660.8%, respectively. These results indicate that pressure-differential puffing drying is superior in creating loose structures and achieving high-quality persimmon chips, making it the preferred processing method.