Long-term Storage and L-ascorbic Acid in Milk

September 22/Biotech Law Weekly -- "The goals of a recent study were to determine L-ascorbic acid concentrations in various milk products and to evaluate the effect of storage time on L-ascorbic acid in milk. Commercial plain milk samples were obtained from either a raw-food market or a supermarket, in Mae Hia, Mueang District, Chiang Mai Province, Thailand, during July, 2008," scientists writing in the Southeast Asian Journal of Tropical Medicine and Public Health report.

"The types of milk were separated based on fat percentages (non fat-0%, low fat-1.5%, full fat-3%) and their method of processing (pasteurization, UHT). All samples were collected, transported and measured for their L-ascorbic acid concentrations on the same day. The expiration date, type of milk, and source of milk were recorded. Pasteurized milk had higher L-ascorbic acid levels than UHT milk (p <0.05), but 110 differences of L-ascorbic acid levels were seen among the milk fat percentage groups. The L-ascorbic acid level was significantly positively related to time before the expiration date of the milk, indicating that increased storage time of milk is related to decreased L-ascorbic acid concentration in the milk," wrote N. Nalame and colleagues, Chiang Mai University.

The researchers concluded, "Longer milk storage times resulted in lower L-ascorbic acid levels and pasteurized milk has higher L-ascorbic acid level, than UHT milk."

Nalame and colleagues published their study in Southeast Asian Journal of Tropical Medicine and Public Health ("Loss of L-ascorbic Acid in Commercian Drinking Milk Caused by Milk Processing and Storage Times." Southeast Asian Journal of Tropical Medicine and Public Health, 2009;40(4):848-851).

Additional information can be obtained by contacting W. Suriyasathaporn, Chiang Mai University, Faculty Vet. Medical, Ruminant Clinic, Chiang Mai 50100, Thailand.

From the September 28, 2009, Prepared Foods E-dition