Microbial and enzymatic changes in natural soursop puree during storage

Microbial and enzymatic comparisons were made on natural soursop puree stor ed at 15, 4 and -20 degrees C without pasteurisation and with pasteurisatio n at 79 degrees C for 69 s. Results showed that pasteurisation caused signi ficant decrease in microbial count in soursop puree from 6.4 x 10(3) to 8.5 x 10(1) cfu per g. Generally, storage at -20 degrees C exhibited greater s tability of samples as compared to those kept at 4 and 15 degrees C. In con trast to microbial reduction, pasteurisation caused significant increase in cloud from 0.318 to 0.529 and completely inactivated the pectinesterase en zyme. The puree packed into foils kept at 4 degrees C exhibited decreased c loud loss as compared to others packed in cans and bottles kept at 15 and - 20 degrees C. No pectinesterase enzyme regeneration was observed for pasteu rised puree in this study during 12 weeks of storage time. (C) 1999 Elsevie r Science Ltd. All rights reserved.