Quality of fermented dairy products beyond best before date

Detta är en Master-uppsats från SLU/Department of Molecular Sciences

Sammanfattning: Date labelling is one factor influencing food waste in consumer households and evaluation of optimum shelf life is a tool food industry can use to contribute to di-minished food waste. This explorative pilot study aimed to investigate how quality of sour milk and yogurt changed beyond best before date. Sour milk and yogurt were stored in 8°C and 15°C for a total of 34 and 56 days, respectively. Instrumen-tal measurements of pH, water holding capacity (WHC) and rheological behaviour were performed along with microbiological and sensory analysis. Lowest pH was observed at best before date and WHC was stable through storage. The solid-like properties of sour milk were temperature dependent and decreased during storage. The solid-like properties of yogurt increased during storage. Viability of Strepto-coccus spp. was more apparent in yogurt while other species of lactic acid bacteria were dominant in sour milk. Storage temperature appeared to be more influential on microbiological viability in yogurt. Yogurt maintained its microbiological quality beyond best before date but the observed fungal growth in sour milk, beginning at best before date, needs to be further investigated. The sensory evaluation showed that both products were associated with creaminess at best before date and associ-ated with the attribute thin thereafter. Sour milk was associated with musty after best before date, which might relate to fungal growth. Further research is required to determine if the observed changes in sensory attributes have a significant influ-ence on consumer acceptability.

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