ACTIVITY AND STABILITY OF α‐ AND β‐AMYLASE AT TEMPERATURES FROM .4° TO ‐23°C

Abstract

ABSTRACTα‐ and β‐Amylase activity were determined at 4°, ‐13°, ‐18° and ‐23°C in model systems and in a sweet potato puree system for different periods of time. In the model systems, commercially purified swine pancreatic ol‐amylase and sweet potatoβ‐amylase at 0, 0.5, 1.0 and 1.5 μg/0.5 ml concentrations were used to react with 0.5 ml of a 2% soluble potato starch substrate for 112 days. In the sweet potato puree system, samples prepared from cured and noncured roots were frozen and stored for 56 days. As an index of amylase activity, accumulated maltose was determined after different periods of storage. Also, the stability of the enzymes as affected by low temperatures was determined in the sweet potato puree. In the model systems, α‐ and β‐amylase showed constant activity at 4°, ‐13°, ‐18° and ‐23°C for different periods of storage, up to 113 days. Amylase activity did increase with enzyme concentration. Both enzymes were active at ‐23°C. In the noncured sweet potato puree system, (α‐ and β‐amylase were active at 4°C for up to 28 days, but were essentially inactive at ‐13°, ‐18° and ‐23°C. In the cured sweet potato puree system, α‐ and β‐amylase were stable for up to 28 days at 4°C. Enzyme stability in samples from noncured roots was not affected for up to 14 days of storage at 4°C, but decreased considerably thereafter. α‐ and β‐Amylase stability in all sweet potato puree samples stored for 56 days at ‐13°, ‐18° and ‐23°C was not affected.