Amylolytic activity in stored potato tubers. 1. Estimation usingp-nitrophenyloligosaccharides

A β-Amylase in Potato Tubers Is Induced by Storage at Low Temperature

“…Our finding that /3-amylase is induced by cold treatment of the stored tubers is in agreement with data presented by Cottrell et al (1993) and Cochrane et al (1991b). These earlier studies relied on the specificity of PNPG5 as substrate for jS-amylolytic activity.…”

“…Most previous reports of /3-amylase in potato tubers have been based on indirect evidence (Davies and Ross, 1987;Cochrane et al, 1991aCochrane et al, , 1991bCottrell et al, 1993;Viks0-Nielsen et al, 1997). Only Fan (1975) demonstrated directly that tubers contain a /3-amylase.…”

“…Morre11 and ap Rees (1986) concluded that the degradation of starch in cold-stored potato tubers was phosphorolytic because they detected no amylase activities in the tubers. However, several other authors (Sowokinos et al, 1985;Davies and Ross, 1987;Cochrane et al, 1991b;Cottrell et al, 1993) have detected substantial activities. This discrepancy may be due to the use of different assay procedures.…”

“…Low storage temperature has been reported to result in increased activity of both a-amylase and p-amylase (Cochrane et al, 1991b;Cottrell et al, 1993), as well as phosphorylase (Claassen et al, 1993). On the other hand, Kennedy andNielsen et ai.…”

“…A range of starch-degrading enzyme activities have been reported in potato tubers, including a-amylase, isoamylase, p-amylase, a-glucosidase, and phosphorylase (Gerbrandy et al, 1975;Kennedy and Isherwood, 1975;Fan, 1975;Killilea and Clancy, 1978;Schneider et al, 1981;Cochrane et a]., 1991aCochrane et a]., , 1991bCottrell et a]., 1993). However, it is not clear whether the degradation is primarily amylolytic or phosphorolytic.…”