Kinetic modelling of drying and conversion/degradation of isoflavones during infrared drying of soybean (original) (raw)
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Spray drying of the soybean extract: Effects on chemical properties and antioxidant activity
Lwt - Food Science and Technology, 2008
Recent findings that many human chronic diseases are associated with oxidative stresses have instigated the search for dietary antioxidants. Isoflavones, a special phenolic group found in soybean, have been found to act as antioxidant in some model systems. The aim of this work was the evaluation the effects of spray drying on the chemical and biological properties of soybean extract. The total polyphenol contents in the concentrated soybean extract (CSE) and spray dried soybean extract (SDSE) were determined by Folin-Ciocalteau method and HPLC was utilized for the quantification of the genistein, active compound used as a chemical marker. The evaluation of antioxidant activity of CSE and SDSE was assessed by the hydrogen-donor ability to 2,2-diphenyl-1-picrylhydrazyl radical (DPPH d ). The results indicated that the inlet gas temperature showed significant effect on the total polyphenol, protein and genistein contents of the dried extracts. The SDSE obtained this work showed high antioxidant activity, opening perspectives for its use as food additive and/or ingredient.
Food Chemistry, 2011
The aim of the present research was to determine an optimal acid hydrolysis condition using drying oven and microwave assisted methods to estimate isoflavone contents by RP-HPLC in soybean. All isoflavone glucosides were completely converted to their aglycones at 120 min for drying oven and 50 min for microwave. Optimal extraction time of the highest isoflavone aglycone content after acid hydrolysis was achieved in 3 h. These results indicated that the optimised hydrolysis and extraction conditions of isoflavones in soybean were: soybean (1 g) hydrolysed by 10 ml of 1 N HCl at 100°C for 50 min using microwave assisted acid hydrolysis method, and then 15 ml of EtOH was added to the mixture which leaved alone for 3 h at room temperature for complete extraction. Thus, microwave is an easy, consumed less time, and reliable acid hydrolysis method to estimate soybean isoflavones in comparison with drying oven method.
Agronomy
Over the last few decades, many researchers have investigated in detail the characteristics of bioactive compounds such as polyphenols, vitamins, flavonoids, and glycosides, and volatile compounds in fruits, vegetables and medicinal and aromatic plants that possess beneficial properties, as well as consumer acceptance and preference. The main aim of this article is to provide an updated overview of recent research endeavors related to the effects of the drying process on the major bioactive/effective compounds in agricultural products. Particular emphasis was placed on details related to the changes occurring in vitamin C, polyphenols, flavonoids, glycosides and volatile compounds, as well as the antioxidant activity. An analysis of the degradation mechanisms of these compounds showed that vitamin C, phenols, flavonoids and glycosides react with oxygen during the convective drying process under high drying temperatures, and the reaction rate results in degradation in such bioactive ...
Food Chemistry, 2008
The kinetics of the isoflavone transformations (diadzin, diadzein, genistin and genistein) and moisture content in soaked soybeans were studied in the temperature range 30-85°C. The evolution of the moisture was described by Peleg's model, and a modified first order kinetic equation was used to predict the transformation profiles of different isoflavones in the soaked soybeans. The dependency, on temperature, of the kinetic parameter was modelled by the Arrhenius equation and empirical equations. The measured b-glucosidase activity at different temperatures justifies the experimental profiles of isoflavone conversion.
2008
The equilibrium moisture content of soybean grains under combined near-infrared radiation and hot-air fluidized-bed drying was determined. The equilibrium moisture content for soybean grains was measured by using the static method in the controlling ranges of temperatures and relative humidity between 40 to 60 o C and 11 to 81%, respectively. The experimental equilibrium moisture content and relative humidity data were used for determining the desorption isotherms of soybean grains. Afterward, the desorption isotherms data were compared with five equations, namely, modified Henderson, modified Oswin, modified Halsey and modified Chung-Pfost. Apparently, modified Helsay's equation was found to satisfactorily describe for the estimation of the equilibrium moisture content of soybean grain, providing the highest R 2 (0.972780) and the lowest SSE (0.01612).
Journal of Food Process Engineering, 2014
The kinetics of the hot-air drying of soybeans was modeled in order to evaluate the influence of temperature and velocity on the kinetic parameters. A convective dryer with air temperature from 30 to 195C and air flows of 0.75, 1.35, 2.0 and 2.5 m/s was used. Three different mathematical models were applied to simulate the drying process (two empirical equations, exponential and Page's, and Fick's diffusion model) and the diffusivity coefficient increased from 2.5 × 10 −11 to 6.69 × 10 −10 m 2 /s for a range of air temperature between 30 and 195C. Both temperature and velocity influenced drying rate. The differential evolution optimization method was used toward parameter estimation. The goodness of fit of the proposed models, evaluated using linear regression coefficient (R 2 ), chi-squared parameter (χ 2 ) and root mean square error, indicated a satisfactory validation, mainly regarding to the exponential and Page's models.
Drying Technology, 2022
Drying is one of the foremost and important steps during the processing of agricultural crops, medicinal plants and herbs to preserve their properties. The present review provides a detailed overview regarding the effect of drying techniques on the physio-chemical properties (microstructure, color, aroma composition) and bioactive compounds (phenolic compounds, carotenoids, essential oils, etc.) of plant materials. Factors affecting different drying processes and their optimization strategies have also been discussed. Furthermore, current trends in the development of drying techniques for plant materials in terms of the retention of their bioactive compounds are critically analyzed. Based on the published research articles, oven drying, and microwave drying are the preferable techniques for most plant parts; while for drying the plant extract, freeze/spray drying methods have gained higher interest. Finally, recommendations are made considering the better use of drying techniques for both plant materials and retention of their bioactive compounds.
Original article: Thermal dynamic properties of isoflavones during dry heating
International Journal of Food Science & Technology, 2010
Thermal stabilities of major soya isoflavones at different dry-heating temperatures were determined in this study. The conversion of glucoside isoflavones to aglycone isoflavones was monitored as well. The thermal degradation of the isoflavones: glucoside form daidzin, glycitin, and genistin and aglycone form daidzein, glycitein, and genistein followed first-order reaction kinetics at heating temperatures 100, 150, and 200°C. The degradation rate constants of the six isoflavones were not significantly different at 100°C. However, the constants increased with increasing heating temperature. The half-life for the glucoside and aglycone isoflavones was from 144 to 169 min and 139 to 176 min at 100°C, respectively. They decreased rapidly to 15.7-54.7 and 36.0-90.7 min when temperature increased to 150°C. When heated at 200°C, they further decreased to 5.8-6.0 and 15.7-21.2 min, respectively. The order of thermal stability from lowest to highest was glycitin < genistin < daidzin < glycitein < genistein < daidzein at temperature below 150°C. However, their thermal stabilities were not different at 200°C. The conjugated glucosides were cleaved from the isoflavones to produce their corresponding aglycones when heated at 150°C or higher. The production of glycitein increased constantly and was the highest among the three aglycone isoflavones.