HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Emmons, D. B. Search for Related Content PubMed Articles by Emmons, D. B.

Inactivation of Pepsin in Hard Water¹

Food Research Institute, Research Branch, Canada Department of Agriculture, Ottawa, Canada

ABSTRACT

Pepsin is inactivated quickly by high pH when diluted with hard water at ambient temperatures in the cheese plant, explaining occasional problems in coagulating milk. "Waters A and B from two cheese plants contained 260 and 186 ppm alkalinity as CaCO₃, 294 and 770 ppm total hardness as CaCO₃, and 317 and 227 ppm bicarbonate. After holding 1:40 dilutions of pepsin in Waters A and B for 10 minutes, milk-coagulating activity was reduced at 30 C by >90 and 80% and at 20 C by 25 and 15%. Dilution of mixtures of rennet and pepsin in the same waters resulted in higher pH and faster inactivation of pepsin. Rennet was relatively stable under these conditions. Alkalinity, or buffer capacity, of water was more important than total hardness in determining its pepsin-destroying potential. Temperature (<20 C.) and pH (<6.5) should be low to maintain activity of pepsin during dilution and adding to milk. Suggestions for obviating this potential problem are given.

¹ Contribution no. 143 from the Food Eesearch Institute.