Changes in isoflavones concentrations in cheese during processing and ripening
2011
Krizova, L.,Vyzkumny Ustav pro Chov Skotu, Pohorelice (Czech Republic). Oddeleni Vyzivy Zvirat a Kvality Zivocisnych Produktu | Vesely, A.,Agrovyzkum, Pohorelice (Czech Republic). Oddeleni Vyzivy Zvirat a Kvality Zivocisnych Produktu | Trinacty, J.,Agrovyzkum, Pohorelice (Czech Republic). Oddeleni Vyzivy Zvirat a Kvality Zivocisnych Produktu | Schulzova, V.,Vysoka Skola Chemicko-technologicka, Prague (Czech Republic). Ustav Chemie a Analyzy Potravin | Hurajova, A.,Vysoka Skola Chemicko-technologicka, Prague (Czech Republic). Ustav Chemie a Analyzy Potravin | Hajslova, J.,Vysoka Skola Chemicko-technologicka, Prague (Czech Republic). Ustav Chemie a Analyzy Potravin | Kvasnickova, E.,MILCOM, Tabor (Czech Republic) | Havlikova, S.,Vyzkumny Ustav Mlekarensky, Prague (Czech Republic)
The aim of the study was to determine possible changes in isoflavones concentrations in cheeses made from either control or isoflavone-enriched milk during manufacturing and ripening. The experiment was carried out on four high-yielding Holstein cows that were divided into two groups with similar mean milk yield. Control cows were fed a diet based on extruded rapeseed cake (C) while experimental animals were fed a diet based on extruded full-fat soya (S). The experiment was carried out in the form of a cross-over design and was divided into 2 periods of 14 days (a 10-d preliminary period and a 4-d experimental period). Cows were fed individually twice daily ad libitum a diet based on maize silage, lucerne hay and supplemental mixture. In each period, 20 kg of morning milk was collected from each group for cheese processing. After pasteurisation (65 deg C, 30 min.) a total of 5 kg of milk from each sample in each period was weighed out to make cheese with a low-heated curd. Cheeses were salted in 20% solution of NaCl for 3.5 h and allowed to ripen for 90 days at 15 deg C. Data concerning the nutrients intake, milk yield and concentration of isoflavones were analysed by means of multifactor analysis of variance using the GLM procedure of the Statgraphics 7.0 package. Average daily isoflavones intake in S (1,284.7 mg/d) was higher than in C (2.9 mg/d, P less than 0.001). Milk yield expressed in 4% FCM did not differ significantly between groups. Concentration of daidzein, genistein and glycitein in pasteurised full fat milk was similar in both groups. S milk had higher concentration of equol (26.7 microg/L) than C milk (4.0 microg/L). C cheese contained 32.1 microg/kg of daidzein and 5.6 microg/kg of equol while S cheese contained 17.5 microg/kg of daidzein and 24.3 microg/kg of equol. During a 90-day ripening percentage decrease in isoflavones concentration was lower in S than in C. Daidzein concentration was reduced by 47% in C and by 37% in S. Genistein concentration decreased by 51% in C and by 31% in S, glycitein concentration by 46% in C and by 29% in S, and equol concentration by 50% in C and by 38% in S.
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