Preparation and Properties of Papain Precipitated from Fresh Latex of Papaya Fruits (Carica papaya)

Abstract

Papain was precipitated from cysteine hydrochloride extract of fresh latex of papaya fruits planted in AlexandriaGovernorate, Egypt. Three precipitants; namely, ethyl alcohol, acetone and sodium chloride resulted in proteolyticactivity recovery 84.8 (of three fractions), 85.2 and 76.7 %, respectively. Acetone was found to be the most promisingrapid and simple conditions for preparing acetone dry powder of partially purified crude papain. Papain propertiesindicated that the maximum activity was attained at pH 7.5–8.0, and temperature of 75 -85°C. The activity was notaffected by Na+ or Ca++ ions. Various degrees of inhibition were exerted by Ni+,+, Co++, Pb ++,and Hg++., while Cu++,caused complete inhibition .On the other hand, the proteolytic activity increased to various levels, in the presenceof Sn++, cyanide, thioglycolic acid, and cysteine hydrochloride. The catalytic activation (49%) of Sn++ was found todepend to some extent on the concentration. A mixed stored papain-oryzae protease preparation ,was found to retain71, 63, and 54 % of its proteolytic activity upon storage at 25°C for 1, 2 ,and 3 months ,respectively. The retainedactivity was more pronounced, being 92, 80,and 69 %, respectively upon storage at –5°C for the aformentioned durations,accordingly, storage at –5°C for up to 2 months, was recommended. The storage stability of papain powder andsolutions were studied. A papain-oryzae protease preparation was formulated for further use in meat tenderization.