Preservation of Cheese and Plain Yogurt by Low-dose Irradiation

J Food Prot. 1980 Feb;43(2):114-118. doi: 10.4315/0362-028X-43.2.114.

Abstract

Irradiation preservation of Turkish kashar cheese and plain yogurt was studied using very low doses of Co-60 radiation. No side effects were observed below 0.15 Mrad. The number of bacteria killed was directly related to total dose up to 0.02 Mrad, then the effectiveness of the dose decreased. Coating cheese samples with a sorbic acid solution helped in reducing the number of bacteria by about 10-12% in irradiated samples. The shelf-life of irradiated samples stored at refrigerator temperature was almost the same as that of ones coated with sorbic acid but stored at room temperature. Mold formation in irradiated samples took three to four times longer than in nonirradiated ones. With plain yogurt the effect of total dose seemed to be the same as in cheese. Irradiation increased the shelf-life of yogurt three- to four-fold. Preservation by irradiation combined with refrigeration increased the shelf-life about five-fold.