Changes in isoflavones concentrations in cheese during processing and ripening

Abstract

The aim of the study was to determine possible changes in isoflavones concentration in cheese made from either control or isoflavone-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. After 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 isoflavones content. 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 (1284.7 mg/d) was higher than in C (2.9 mg/d, P < 0.001). Milk yield expressed in 4% FCM did not differ significantly between groups (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). After 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 isoflavones 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.

Multiresidue determination of estrogens in different dairy products by ultra-high-performance liquid chromatography triple quadrupole mass spectrometry

“…As indicated in the introduction section, the content of phytoestrogens in kefir samples has not been reported up to now since these compounds have not been previously analyzed in such matrices. Regarding cheese samples, the obtained results, in the range of 1.76-46.7 g/kg for daidzein, glycitein and enterolactone, are comparable to the content previously determined by Křížová et al [7] who reported values around 11.7-30.5 g/kg for daidzein, genistein and glycitein, and slightly lower that the data reported by Kuhnle et al [6] who found enterolactone in concentrations of 30-230 g/kg in different type of cheese products. As it was demonstrated by Křížová et al [7], these differences can be associated with the animal diet as well as the type of process applied to each product which can modify considerably the initial level of phytoestrogens present in the raw material used for its preparation.…”

“…As it was indicated in the introduction section, only a few studies have been published regarding the evaluation of estrogenic compounds in milk or milk derivatives [6,7,[17][18][19][26][27][28][29] except for kefir samples, which has not been previously analyzed. Concerning cheese samples, it should be indicated that it has only been previously analyzed to determine phyto-, natural and synthetic estrogens, but not mycoestrogens [6,7,17,18]. In this sense, Guoliang et al applied a simple solvent extraction procedure followed by HPLC-FD with a previous derivatization with ethyl-acridinesulfonyl chloride for the determination of E 1, E 2 and E 3 among other type of compounds.…”

“…With respect to phytoestrogens analysis, Kuhnle et al [6] applied a LLE using 2 mL of MeOH in sodium acetate to 100 mg of sample followed by a hydrolysis with ␤-glucuronidase/␣-glucosidase and a SPE in C 18 cartridges for the determination of twelve phytoestrogens by HPLC-QTrap-MS/MS, obtaining a LOQ for all analytes of 50 g/kg. Křížová et al [7] used the same hydrolysis reactant and ethyl acetate for the LLE of four phytoestrogens from cheese samples prior their analysis by HPLC-IT-MS/MS. In this case the LOQs were around 6-17 g/kg.…”

“…Most of them are naturally found in plants whereas others like the lignans enterolactone or enterodiol are obtained as products of animal metabolism. In both cases, and as a result of the vegetable composition of animal feed, they can appear in milk and, consequently, in dairy products [6,7].…”

“…However, and probably because of the complexity of dairy products, the analysis of these compounds in such products has not been so widely tackled as for other simpler matrices like, for example, water samples [15,16]. In fact, only some phyto-, natural and synthetic estrogens have been analyzed in a few occasions in cheese samples (cow cheese) [6,7,[17][18][19], while the analysis of the presence of these groups of compounds in kefir samples has not been reported in the bibliography. In these studies, different extraction techniques were applied including liquid-liquid extraction (LLE) [7,19], LLE combined with solid-phase extraction (SPE) [16,18] and the application of miniaturized techniques as hollowfiber liquid-phase microextraction (HF-LPME) [17].…”