Kvalitet fermentisanog mlečnog napitka pakovanog u različitim uslovima / Quality of fermented milk beverage packed under different conditions

Functional milk-based beverage was obtained by applying 10% v/v of kombucha’s inoculum cultivated on a black tea sweetened with sucrose for the fermentation of milk with ;0,9% milk fat content. The beverage was packed in a different packaging materials: polyethylen (PE) and polyamidpolyethylen (PA/PE) bags and polyprophylen (PP) cups closed with aluminium (Al) foil lids under atmospheric conditions (ATM) and in modified atmosphere (MAP: CO2 - 40% and N2 - 60%). Products were stroraged for 15 days at 4°C. The composition and changes in the headspace atmosphere, after production and during the storage, were analysed. The influence of packaging material properties and packaging conditions on the biochemical transformations of the milk components influenced by kombucha starter were analysed as well. On the bases of the obtained results of characterisation of packaging materials (physico-mechanical, structural and barrier properties) it can be concluded that PA/PE and PP materials are justified to be used in modified atmosphere conditions for the analysed beverage. The product after production contained approximatelly 34,45% lactose lower than milk. The content of lactose decreased during storage and the fermentation process of lactose was the most intense in atmospheric conditions in PA/PE packaging material which is consistent with a decrease of the pH value at the end of storage. The highest content of L-lactic acid in comparision with the value after production had PP ATM samples (0,896g/100g which is increase of 22,7%). The content of D-galactose was 0,548 g/100g in a beverage and after 15 days it increased in all samples and the highest value was found in PP ATM - 0,641 g/100g. The content of ethanol generally decreased, except in case of PP ATM samples where it stayed at the same level as after production. The results of determination of a content of B-vitamins complex (B1, B2 and B6) showed that vitamin B2 was of the highest value in the beverage after production. The content of analysed vitamins decreased during storage as a function of applied packaging materials, packaging conditions and time. Considering identified and quantified changes of the analysed parameters of kombucha fermented milk beverage quality, it can be concluded that 15 days of storage is acceptable from the usage of choosen packaging materials and packaging conditions point of view. There is no signifficant differences in quality of kombucha fermented milk beverages packed in atmospheric and modified atmosphere conditions.