Thermal Stability of Dehydrated α-Amylase in Trehalose Matrices in Relation to its Phase Transitions

Loss of solubility of α-lactalbumin and β-lactoglobulin during the spray drying of whey proteins

“…A change in conditions, such as temperature, unfolds the three-dimensional structure which allows cross-linking interactions to be made between protein molecules such as, protein-protein hydrophobic, electrostatic, hydrogen-bonding and disulfide-sulfhydryl interactions. These interactions result in aggregation, coagulation and finally precipitation (Creighton, 1992;Pelegrine & Gasparetto, 2005;Terebiznik, Buera, & Pilosof, 1997). In the case of a-lactalbumin an increase (above 9.0) or decrease (below 4.0) in pH value results in the dissociation of Ca 2+ ions from the molecule which destabilises the molecular configuration and thus also leads to denaturation (Boye, Alli, & Ismail, 1997).…”

Thermostability and Browning Development of Fungal α-amylase Freeze-dried in Carbohydrate and PVP Matrices

“…The fall in remaining α-amylase activity above the Tg in sugar matrices at 20% RH for trehalose and raffinose; above 11% RH for lactose; and at all the assayed conditions for sucrose, may be related to the crystallization of sugars (9). Since samples were stored in open vials within the sealed desiccators, the water content of the remaining amorphous sugar fraction did not change when sugars formed either anhydrous or hydrous crystals.…”

“…The scan rates were 5 °C/min and the transition onset was taken as the Tg value. Addition of the enzyme to the matrices had a negligible effect on the Tg of the matrix, as determined previously (9).…”

Effect of water activity on the thermal stability of Thermomyces lanuginosus xylanases for process time–temperature integration

“…When the proposed TTIs are adjusted to low levels of water activity a decrease on the rate of enzyme inactivation, corresponding to higher D-values, was observed. The heat stability of enzymes markedly increases at low water activity conditions as mobility of the protein molecules is reduced, which inhibits conformational changes related to activity loss (Terebiznik et al, 1997). Conformational mobility is necessary for partial unfolding, the first step of enzyme thermal inactivation (Lapanje, 1978;Tanford, 1968).…”