STABILIZATION OF PAPAIN FROM PAPAYA PEELS

Crude papain in papaya peels was stabilized before drying by the addit ion of various chemicals (ascorbic acid, sodium ascorbate, erythorbic acid, sodium erythorbate, sodium metabisulfite, sodium tetrathionate, 4-hexylresorcinol, t-butyl hydroquinone [TBHQ], rutin, alpha-tocophero l, trehalose, and sucrose). Chemicals were added to the ground papaya peels at 0, 0.12, 0.25, 0.5, 0.75, 1, 1.25, and 1.5% (w/w). Drying tem peratures were 40, 55 and 60 degrees C. Enzyme activity was measured b efore and after drying by the casein digestion method. Percentage of e nzyme activity retained (% EAR) was calculated by assigning a value of 100% EAR to fresh peels. Possible synergism between chemicals was als o studied for a 1:1 ratio chemical/chemical at 1% total concentration. The highest % EAR was obtained at 55 degrees C for all chemicals exce pt for sucrose and trehalose which showed their best effect at 40 degr ees C. TBHQ, rutin, cc-tocopherol and 4-hexylresorcinol showed a desta bilizing effect. Maximum protective effect occurred at 1% concentratio n. At this concentration sodium tetrathionate showed the best protecti ve effect (90% EAR) followed by sodium metabisulfite (85% EAR), while both sodium ascorbate and sodium erythorbate retained 75% of the origi nal activity. Ascorbic acid and erythorbic acid were 10% less effectiv e than their corresponding sodium salts, possibly due to lower pH. Tre halose showed only 57 % EAR while sucrose failed to produce any apprec iable effect. No synergistic effect was shown by any combination of ch emicals.