Intensification of the synthesis of flavour compounds in yogurt by milk enrichment with their precursors
2006
Baranowska, M. (University of Warmia and Mazury, Olsztyn (Poland). Dept. of Dairy Science and Quality Management), E-mail: [email protected]
The aim of the present study was to test the possibility of enhancing the synthesis of flavour compounds with a traditional yogurt culture and a culture containing microflora composed of: S. thermophilus : L. delbrueckii ssp. bulgaricus : Bifidobacterium (TBB yogurt) and Str. thermophilus : L. acidophilus : Bifidobacterium (TAB yogurt). Milk was enriched with lactose (10 g/L), glucose (0.7 g/L), sodium proteinate (25 g/L), sodium citrate (3 g/L), a mixture of citric acid (1 g/L) and sodium citrate (3 g/L), and threonine (1 and 3 g/L). The following determinations were made in fresh yogurts (ripened for 24 h) and yogurts stored for 7 and 14 days: active acidity, lactic acid - according to Lunder, acetaldehyde, diacetyl, acetoin, ethanol, and volatile free fatty acids by gas chromatography. All products were evaluated organoleptically. It was found that from among the substances whose effects on the synthesis of flavour compounds were studied in this experiment particular attention should be paid to threonine. The addition of this amino acid significantly affected the rate of acetaldehyde formation (an increase by 10.24-22.56 mg/L) in all kinds of yogurt. The modification of milk composition had a profound influence on the levels (increase or decrease) of all flavour compounds in yogurt samples, as well as on their sensoric attractiveness
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