Sorption isotherm characteristics of aonla flakes

Abstract

The equilibrium moisture content was determined for un-osmosed and osmosed (salt osmosed and sugar osmosed) aonla flakes using the static method at temperatures of 25, 40,50, 60 and 70°C over a range of relative humidities from 20 to 90%. The sorption capacity of aonla decreased with an increase in temperature at constant water activity. The sorption isotherms exhibited hysteresis, in which the equilibrium moisture content was higher at a particular equilibrium relative humidity for desorption curve than for adsorption. The hysteresis effect was more pertinent for un-osmosed and salt osmosed samples in comparison to sugar osmosed samples. Five models namely the modified Chung Pfost, modified Halsey, modified Henderson, modified Exponential and Guggenheim-Anderson-de Boer (GAB) were evaluated to determine the best fit for the experimental data. For both adsorption and desorption process of aonla fruit, the equilibrium moisture content of un-osmosed and osmosed aonla samples can be predicted well by GAB model as well as modified Exponential model. Moreover, the modified Exponential model was found to be the best for describing the sorption behaviour of un-osmosed and salt osmosed samples while, GAB model for sugar osmosed aonla samples.

Sorption behaviour of papayas as affected by compositional and structural alterations from osmotic pretreatment and drying

“…Al-Muhtaseb et al (2004) noticed that the hysteresis effect between desorption and adsorption isotherms depends on compositional and structural changes caused by processing methods. The observation was in agreement with an additional study by Alam and Singh (2011). They reported that the hysteresis effect was observed prominently for un-osmosed and salt-osmosed samples in comparison to sugar-osmosed samples.…”

Sorption isotherms and isosteric heats of sorption of Malaysian paddy

“…Moreover, Jain et al (2010) considered the Oswin as a superior model in describing the sorption characteristics of osmotically dehydrated papaya cubes. A number of studies have shown that GAB model has been successful in providing reasonable fit to sorption isotherms of several foods (Reddy and Chakraverty 2004;Erbas et al 2005;Togrul and Arslan 2006;Alam and Singh 2011;Rakshit et al 2011;Koua et al 2012). The results have shown that Smith model was in good agreement with the experimental sorption data of paddy throughout the whole water activity range.…”

HR-LC-ESI-Orbitrap-MS-Based Metabolic Profiling Coupled with Chemometrics for the Discrimination of Different Echinops spinosus Organs and Evaluation of Their Antioxidant Activity

“…Quantitative analysis was performed using the external standard method (ferrous sulfate, 0.1-2 mmol), correlating the absorbance (λ 450 nm) with the concentration, and the spectrophotometric readings were carried out on a Varian Cary 50 Scan spectrophotometer (Varian, Leini, Turin, Italy). The results are expressed as millimoles of Fe 2+ per g of dry extract [20].…”

“…Quantitative analysis was done using the external standard method, employing ferrous sulfate in the range of 0.1-2 mmol, correlating the absorbance at λ = 593 nm with the concentration. The results were expressed as millimoles of Fe 2+ per g of dry extract [20].…”