Changes in isoflavones concentrations in cheese during processing and ripening

KŘIŽOVA, L. , VESELÝ, A. , TŘINACTÝ, J., SCHULZOVA, V. , HURAJOVA, A. , HAJSLOVA, J., KVASNICKOVA, E. , HAVLIKOVA, S. : Changes in isofl avones concentrations in cheese during processing and ripening. Acta univ. agric. et silvic. Mendel. Brun. , 2011, LIX, No. 1, pp. 153–162 The aim of the study was to determine possible changes in isofl avones concentration in cheese made from either control or isofl avone-enriched milk during manufacturing and ripening. The experiment was carried out on four high-yielding lactating Holstein cows that were divided into two groups with similar mean milk yield. The control group of cows was fed a diet based on extruded rapeseed cake (C) while the experimental group of animals was 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 the 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. A er pasteurisation (65 °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 °C. During technological processing samples were taken to determine isofl avones content. Data concerning the nutrients intake, milk yield and concentration of isofl avones were analysed by means of multifactor analysis of variance using the GLM procedure of the Statgraphics 7.0 package. Average daily isofl avones intake in S (1284.7 mg/d) was higher than in C (2.9 mg/d, P 0.05). Concentration of daidzein, genistein and glycitein in pasteurised full fat milk was similar in both groups. Milk from S group had higher concentration of equol (26.7 μg/L) in comparison to C group (4.0 μg/L). A er processing cheese in C contained 32.1 μg/kg daidzein and 5.6 μg/kg of equol while cheese in S contained 17.5 μg/kg of daidzein and 24.3 μg/kg of equol. During a 90-day ripening percentage decrease in isofl avones concentration was lower in S than in C. Concentration of daidzein was reduced by 47% in C and 37% in S. Concentration of genistein decreased by 51% in C and 31% in S, concentration of glycitein by 46% in C and 29% in S and concentration of equol by 50% in C and 38% in S. soybean, equol, milk, dairy products Soybean-derived isofl avones daidzein and genistein have attracted a lot of attention due to their diverse pharmacological and antioxidant properties including anticarcinogenic (e.g. Messina and Barnes, 1991; Hirano et al., 1994), antimutagenic (Hartman and Shankel, 1990), and antioxidant (Jha et al., 1985) activities, as well as antiproliferative eff ects against tumor cells (Hirano et al., 1989), reducing risk of heart disease (Wong et al., 1998) and menopausal symptoms (Chiechi, 1999) and improving bone health (Anderson and Garner, 1997). However, it has been proposed that clinical eff ectiveness of soy protein in cardiovascular, bone, and menopausal health is infl uenced by the ability of human to biotransform daidzein to equol (Setchell et al., 2002). Recent studies found that equol is in vitro more bio-active 154 L. Křižova, A. Veselý, J. Třinactý, V. Schulzova, A. Hurajova, J. Hajslova, E. Kvasnickova, S. Havlikova than its precursor daidzein, it has a higher oestrogenicity (e. g. Muthyala et al., 2004; Kostelac et al., 2003; Setchell et al., 2002; Morito et al., 2001), is a more potent antioxidant (e. g. Arora et al., 1998; Rimbach et al., 2003; Turner et al., 2004) and possesses antiandrogenic properties (Lund et al., 2004). Furthermore, equol has a higher eff ective free fraction circulating in human serum (Nagel et al., 1999) and a slower plasma clearance (Setchell et al., 2002) compared to daidzein. Equol is exclusively formed during digestion by the intestinal microbiota (e. g. Atkinson et al., 2004; Bowey et al., 2003). Nevertheless studies (e.g. Lampe et al., 1998; Rowland et al., 2000) have shown that there are substantial inter-individual variations in the bacterial metabolism of isofl avones in the gut resulting in a low proportion of adult population (30–50%), so called equol producers, that is able to convert daidzein into equol (Atkinson et al., 2005). However, oral administration of equol seems to be an alternative strategy for obtaining the health-promoting benefi ts of this substance in non-equol producers as documented by Setchell et al. (2002) who has reported that an oral dose of 25 mg of equol was rapidly absorbed with maximum plasma concentration observed a er 4–6 h. Also Walsh et al. (2003) and Walsh and Faila (2009) demonstrated stability of equol during simulated gastric and small intestinal digestion and its rapid bioaccessibility. Recent studies suggest (Mustonen et al., 2009; Steinshamn et al., 2008; Kuhnle et al., 2008) that bovine milk and some dairy products can be considered as a potential die tary source of equol for non-equol producing human. Although concentrations of isofl avones in bovine milk and dairy products have been reported e.g. in latter mentioned studies, little is known about changes in isofl avones content during technological processing of milk and dairy products. Only eff ect of heat treatment of milk on isofl avones concentration has been reported previously (King et al., 1998; Uzzan and Labuza, 2004). The aim of the study was to determine possible changes in isofl avones concentration in cheese during manufacturing and ripening. MATERIAL AND METHODS