Effect of pH, sodium chloride and sucrose on heat‐inactivation and reactivation of peroxidases in certain foods

Abstract

The kinetics of heat inactivation and reactivation of peroxidase were examined in extracts of carrots, spinach and apricots. The enzyme from carrots was the most heatstable and showed the highest reactivation during storage whereas the peroxidase from apricots was the most heat-sensitive and showed no reactivation during storage. Higher rates of reactivation were generally observed for samples stored at -5'C compared to those stored at 4 and 18°C. The optimal pH for reactivation of peroxidase from spinach and apricots was pH 8.0. The presence of sodium chloride resulted in higher rates of reactivation during storage whereas sucrose had no significant effect.

Peroxidase Isoforms of Corn Kernels and Corn on the Cob: Preparation and Characteristics

“…An 8-fold increase in POD activity was found following the freezing of kohlrabi (32). When blanched carrots were stored at -5 °C the regenerated soluble POD levels were 150% of the original POD activity and approximately 100% when stored at 4 or 18 °C (27). Intracellular control of POD by phenolics or other organic compounds has been suggested (33).…”

“…Calcium has been shown to affect POD thermal stability (26). Soluble POD was activated 3-fold by the addition of 0.4 to 0.6 mol/L NaCl to carrot and spinach extracts (27). Neither soluble nor membrane-bound corn POD was activated by high concentrations of NaCl and thus, it was preferable to divalent salts for the solubilisation of membrane-bound POD.…”

Peroxidase and polyphenol oxidase thermal inactivation by microwaves in green coconut water simulated solutions

“…The sugars that were added to the solution contributed to decrease POD activity. Gibriel, El-Sahrigi, Kandil, and El-Mansy (1978) showed that the presence of sucrose in the reaction mixture inhibited POD activity in apricot. Chang, Park, and Lund (1988) showed by differential scanning calorimetry that in the presence of 10% sucrose POD thermal stability was reduced.…”

Evaluation of blanching requirements of green French bean (Phaseolus vulgaris L.) pods on basis of thermal resistance of its peroxidase

“…This period, also known as come-up time, therefore does not exert full lethality. Percentage of lethality equivalent to that of instant heating period is taken as its effectiveness [4]. It is used to determine corrected F. Nath [6] found the average come-up time for the TIT tubes to be 2.34 min of which 46.2 % was effective.…”

“…But their use alters the pH and concentration of various ions in the blanching media and the pods. This changes the thermal resistance of PO and thereby blanching requirements [4]. Therefore, thermal resistance of PO was determined in French bean extracts of different pH and blanching requirement of the pods were established.…”