Water vapour sorption behaviour of original and defatted wheat gluten

Abstract

The water vapour sorption isotherms of original and defatted gluten samples, prepared from two wheat cultivars (Spring and Taurus) with good and poor baking performance, respectively, were investigated at 25 and 40ЊC. The GAB isotherm equation described the isotherms well up to a relative humidity of at least 84% at 25ЊC and up to 75% at 40ЊC. The GAB constants of Spring gluten indicated an increased number of adsorption sites and a decreased average interaction energy per binding site at increased defatting (petroleum ether, chloroform). This tendency was also observed for Taurus, however, here no significant differences were found between the solvents. When comparing both cultivars the isotherm analysis indicated less available active sites for water adsorption with a stronger interaction energy per site for Taurus gluten. This stronger interaction is in accord with the higher isosteric heat of adsorption (Clausius-Clapeyron analysis) found at low relative humidities. These findings are related to bread baking performance.

Water Sorption Isotherms and Crispness of Fried Yam Chips in the Temperature Range from 293K to 313K

“…With increasing amounts of adsorbed water, the specific adsorption enthalpy decreases and attains ultimately the level of condensation of pure water. [23] A similar trend was observed by [11,16,21,41] in their work. Figure 8 shows the results of sensory test of fried yam chips at various water activities and temperatures.…”

“…[11,21] The final moisture content at equilibration was determined by drying at 105°C for 8 h. [22] All moisture content was expressed as a percentage of nonfat dry weight because fat is known to exhibit no sorption of water below RH 90%. [23] The initial moisture content of the fried samples was found to be 2.6 ± 0.01% (wb). The equilibrium moisture content at each water activity is the mean value of three replications.…”

Drying characteristics and sorption isotherm of tomato slices

“…Similar effects of moisture on the binding energy of sorption were also reported for potato (Wang & Brennan, 1991), red peppers (Kim, Song, & Yam, 1991), wheat gluten (De Jong, van den Berg, & Kokelaar, 1996), mulberry (Maskan & Gö gü s, 1998) and agaragar (Iglesias & Bueno, 1999).…”

The derivation of the GAB adsorption equation from the BDDT adsorption theory

“…K , as a measure of the range of application of the GAB equation, will diminish as temperature increases. This decrease in the size of K as temperature increases has been recorded by de Jong et al. (1996) and Cepeda et al.…”