Crude papain in papaya peels was stabilized before drying by the addition of various chemicals (ascorbic acid, sodium ascorbate, erythorbic acid, sodium erythorbate, sodium metabisulfite, sodium tetrathionate, 4-hexylresorcinol, t-butyl hydroquinone [TBHQ], rutin, α-tocopherol, 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 temperatures were 40, 55 and 60 °C. Enzyme activity was measured before and after drying by the casein digestion method. Percentage of enzyme activity retained (% EAR) was calculated by assigning a value of 100% EAR to fresh peels. Possible synergism between chemicals was also studied for a 1:1 ratio chemical/chemical at 1% total concentration. The highest % EAR was obtained at 55 °C for all chemicals except for sucrose and trehalose which showed their best effect at 40 °C. TBHQ rutin, α-tocopherol and 4-hexylresorcinol showed a destabilizing effect. Maximum protective effect occurred at 1% concentration. At this concentration sodium tetrathionate showed the best protective effect (90% EAR) followed by sodium metabisulfite (85% EAR), while both sodium ascorbate and sodium erythorbate retained 75% of the original activity. Ascorbic acid and erythorbic acid were 10% less effective than their corresponding sodium salts, possibly due to lower pH. Trehalose showed only 57 % EAR while sucrose failed to produce any appreciable effect. No synergistic effect was shown by any combination of chemicals.
Effect of ascorbic acid on reduced glutathione level in arsenic-loaded isolated liver tissues of rat
