Effect of nitrogen gas flushing treatments on total antioxidant capacity and ascorbic acid content in raw bovine milk during cold storage

Abstract

Continuous nitrogen gas (N-2) flushing extends the shelf life of raw milk (RM) during cold storage. The effect of N-2 treatment on the total antioxidant capacity (TAC) and ascorbic acid (AA) content of RM was determined during cold storage. TAC of RM or deproteinized RM was determined by ABTS and DPPH methods, while L(+)-AA content of RM was determined chromatographically on days 0, 4 and 7 during storage at 6 +/- 1 degrees C. With the ABTS method, the TAC of RM decreased from 472.33 +/- 16.70 to 369.47 +/- 62.06 mu M TEAC while it reduced from 13.30 +/- 0.84 to 8.20 +/- 0.66 mu M TEAC with DPPH method during cold storage. TAC of RM determined with ABTS method decreased after 4 day-storage; however, they remained statistically similar for N-2-treated samples during 7 day-storage. The AA content of RM ranged from 14.06 to 10.76 mg/L during storage but N-2-treatment did not influence AA content significantly. Deproteinization reduced TAC values of milk samples significantly, and the reduction with the ABTS method was about 47.50 % for control samples cold-stored for four days, while it was 11.67 % for N-2-treated deproteinized RM. In conclusion, N-2-flushing through the headspace of milk containing vessels showed a significant protective effect on the antioxidant components of RM during cold storage.