Effect of light transmittance and oxygen permeability of various packaging materials on keeping quality of low fat pasteurized milk: chemical and sensorial aspects

Chemical and sensory changes in low fat (15 g kg−1) pasteurized milk stored under fluorescent light at 4°C in 500 mL bottles made of (a) multilayer pigmented [HDPE (high-density polyethylene)+20 g kg−1 TiO2/HDPE+40 g kg−1 carbon black/HDPE+20 g kg−1 TiO2], (b) monolayer pigmented [HDPE+20 g kg−1 TiO2], (c) clear PET (polyethylene terephthalate) and (d) pigmented [PET+20 g kg−1 TiO2] were monitored for a period of 7 days. Milk packaged in coated paperboard cartons and stored under the same experimental conditions served as the “control” sample. Data were obtained for lipid oxidation, vitamin A and riboflavin content, microbial growth and sensory attributes (odour and taste). Results showed good protection of milk packaged in all packaging materials with regard to microbiological and chemical parameters assessed over the 7-day test period. Vitamin A losses recorded were 11% for multilayer and monolayer pigmented HDPE and pigmented PET bottles vs. 16% for the paperboard cartons and 31% for the clear PET bottles after 7 days of storage. Respective losses for riboflavin were 28% for the multilayer pigmented HDPE bottle and the paperboard carton, 30% for the monolayer pigmented HDPE bottle, 33% for the pigmented PET bottle and 40% for the clear PET bottle. Based on sensory analysis the shelf life of low fat (15 g kg−1) pasteurized milk is approximately 5 days. The best overall protection for the product was provided by the multilayer followed by the monolayer TiO2-pigmented HDPE bottle. Such packaging materials are recently emerging in the fresh milk packaging market.