Comparison of Code Date Reliability for Freshly Bottled Whole, Lowfat and Nonfat Fluid Milk

Abstract

Whole, lowfat, and nonfat fluid milk samples were collected from dairy plants on the day of bottling and each set of the three types of milk was processed from the same raw milk supply. Bacterial analyses for total aerobic count and for specific degradative types were made immediately after collection. Samples were also stored at 1.7, 5.6 and 10.0 C to test for flavor deterioration. Total count of aerobic bacteria and of specific degradative types did not differ significantly among the three types of milk. Organoleptic analysis was made periodically to determine milk quality (flavor score) and defect (flavor). At any of the storage temperatures the keeping quality (days required from bottling to reach a flavor score of < 36) was unrelated to the length of time between bottling and last day of sale (code date) assigned by the processor. At 5.6- and 10.0-C storage, more whole milk samples were criticized for more serious flavor defects (e.g. putrid) than for the less serious ones (e.g. lacking freshness) found in the lower fat milks. Keeping quality of all three types of milks at 1.7- and 5.6-C storage could be predicted from keeping quality determined at 10.0 C with equations previously developed for whole milk.