Abstract
This article describes the evaluation of the anthocyanins stability in yogurts with strawberry, sour cherry, and blueberry fruit preparation during 8-week storage period under refrigerated condition. The differences in anthocyanin degradation rate and color changes between stirred yogurts and fruit-on-the-bottom yogurts (fruit preparation was on-the-bottom of package) were compared. Anthocyanin content in fruit yogurts showed a significant decreased during the storage, especially for the first 2 weeks. There were differences in the rate of pigment degradation between yogurt obtained from a different species of fruit. The half-life of the pigments in stirred yogurt with the preparation of strawberry, sour cherry, and blueberry was found to be 5.5, 6.7, and 19.0 weeks, respectively. The addition of fruit preparation on the bottom of yogurt could be used to reduce the pigment degradation during storage. The half-life of anthocyanin in fruit-on-the-bottom yogurts was 39–63% higher than in the blending samples. A significant alteration in the pigment profile during storage of blueberry yoghurt was observed. The proportion of malvidin-glucosides and acylated anthocyanins increased with time of storage, with a concomitant decrease in proportion of petunidin, delphinidin and peonidin derivatives.
Highlights
Yogurt is one of the most popular fermented dairy products all over the world
Strawberry yogurts directly after the production presented a higher pH and lower acidity than sour cherries and blueberry yogurts, while all products contained similar amounts of lactic acid and this was due to the difference in the acidity of fruit preparation incorporated into yogurts
The mean of titratable acidity of all yogurts stored 8 weeks was significantly higher than that of the yogurts directly after the production. These results suggest that the production of organic acid is continuing at refrigeration temperatures, and this may affect the stability of color and sensory characteristics of yogurts
Summary
Yogurt is one of the most popular fermented dairy products all over the world. Recently, fermented milk products have been gaining more attention by consumers, both because of their nutritional benefits, and the presence of ingested live microorganisms. Color is an important factor of fruit yogurt quality, influencing consumer‘s acceptability of the product It is one of the first characteristics perceived by the senses and is used by consumers for the evaluation of the quality of food products (Giusti and Wrolstad 2003). The shelf life of yogurt products is only 6–8 weeks under refrigerated condition, depending on the production method and packaging material. If fruit preparations are heated and post-processing contamination is avoided, the shelf-life of the fruit-flavored yogurts can be extended to 8 weeks (MacBean 2009). In this short-time period, the shade of yogurt color may become lighter, unattractive for consumers. The food industry has used natural food colorings by the application of intensively pigmented materials to improve
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