Shelf-Life of Pasteurized Fluid Milk as Affected by Age of Raw Milk

Abstract

Increasing raw milk storage time prior to pasteurization may affect product shelf life. Raw milk was stored at 4.5.degree. C for 0, 2, 4 and 6 days prior to pasteurizing. Milk samples from each pasteurized lot were analyzed after continuous storage at 4.5.degree. C for 0, 4, 8, 12, 16 and 20 days. Raw and pasteurized samples were analyzed for coliforms, psychotrophs and total bacteria counts. Flavor scores were also determined. No correlations were significant between raw or pasteurized samples and total bacteria or coliform counts. Flavor score and days held raw, shelf life of the resulting pasteurized product, and interaction of days held raw and shelf life of the pasteurized product were related. Psychrotrophic counts and age of the raw milk were correlated. From correlations of flavor scores with shelf life of the milk, a predictive equation was derived.