Roles of different packaging materials on the quality and shelf life of yogurt

The main functions of food packaging are providing an essential protection from the environment and from chemical and physical challenges. This study evaluated the effect of different packaging material on the chemical, microbiological and sensory characteristics of yogurt during 14 days of storage. To investigate the potential impact of packaging on yogurt quality, five different types of packaging material used including Glass(A), Aluminum(B), non-identified plastic (C), Polypropylene plastic (PP) (D) and mud(E). The tested materials selected based on the highly uses for local yogurt packaging in Kurdistan region. Analyses of samples were carried out at 1st, 7th and 14th days of storage with in the same yogurt process and storage condition. For chemical tests (pH, titratable acidity and dry matter percentage) determined. In all cases, pH values significantly decreased over storage time (ranged from 4.6 to 4.2), whereas titratable acidity (ranged from 0.40% to 1.11%) and dry matter content gradually increased (ranged from 82.30% to 98%). To investigate the microbiological quality of yogurt samples, total viable count was obtained by inoculating the sample on nutrient agar (NA) and potato Dextrose Agar (PDA). During storage the number of isolates obtained varies from one yogurt sample to the other. After 14th days of storage Sample B has the highest bacteria and fungi count at 106 dilutions. For sensory evaluation a total of 12 members (six male and six female) participated and performed sensory analysis during 14 days storage. The result indicated that the yogurt samples did not show any significant difference among sensory properties in the 1st session. The scores of yogurt sample in aluminum container were slightly higher than others in most of the sensory properties in day 14th of storage.