Effect of Various Dairy Packaging Materials on the Headspace Analysis of Ultrapasteurized Milk

¹ North Carolina State University, Raleigh 27695

Milk from three different dairies (each a separate trial: 1, 2, and 3) was standardized to 2% fat and processed at 140.6, 129.4, 118.3, and 107.2°C (temperatures 1, 2, 3, and 4, respectively) for 2 s and packaged into six different packaging boards [standard (A) milk boards with standard seam, juice boards with standard (B) and J- bottom (D) seams, barrier boards with standard (C) and J-bottom (E) seams, and foil (F) boards with J-bottom seam] resulting in 24 different treatments. A Shimadzu 15A series chromatograph equipped with a Porapak-P column was used to measure the headspace of the milk stored at 6.7°C for 1, 2, 3, 5, 10, and 15 wk of storage.

Gas chromatographic headspace analysis for sulfur compounds showed that hydrogen sulfide, methanethiol, and dimethyl sulfide were detected in milk processed at 140.6, 129.4, 118.3, and 107.2°C. In addition, dimethyl disulfide was detected in milk processed at 140.6 and 129.4°C, and dimethyl trisulfide was detected at 140.6°C. Milk processed at 140.6°C contained the most sulfur compounds. Samples C1, E1, and F1 retained the most hydrogen sulfide and methanethiol at 6 d of storage. Methanethiol appeared to be heat-induced. At wk 6, a slightly hammy or cardboardy flavor was detected for milk packaged in boards with standard seams (A, B, and C), and a slightly cooked flavor was detected for milk packaged in barrier and foil boards with J-bottom (E and F) seams. The hammy or cardboardy flavor intensified with storage time, and all of the cooked flavor dissipated at wk 10.

Key Words: ultrapasteurized milk • packaging materials • headspace analysis

Submitted on July 6, 1999
Accepted on August 29, 2000