Impact of skimming and microfiltration processes on equol concentration in milk

Abstract

Equol is a microbial metabolite of isoflavones that could be used as therapeutic agent against several diseases and cancers. Cow's milk could be a potential source of equol in the human diet, but more studies are needed on the changes in equol concentration during the technological processing of milk and dairy products. This first exploratory study sought to assess the impact of industrial skimming and microfiltration processes on equol concentration in conventional cow's milk. The milk samples used in this study came from bulk cow’s milk collected in Wallonia (Belgium), by a local dairy and processed in a local cheese factory. Six random sampling were conducted during spring and, for each of them, samples from raw, skimmed and microfiltered milk were analyzed. Equol was present in all samples at a concentration of between 3.2 and 10.3 µg.L-1. A Wilcoxon's signed rank test was then performed on the difference of data, having raw milk as reference, irrespective of the collection date. The results showed that the skimming process slightly increased the equol concentration in milk and therefore that equol had no or little affinity with the lipid milk fraction. The results also showed that, with the microfiltration process, a small proportion of equol was retained. Equol concentration has returned to the same level as that found in raw milk. This might be because of a chemical affinity either with bigger molecules that are physically retained or through direct interaction with the membrane. This scoping study paves the way for more extensive studies on the interaction between equol and other components of the milk.PhytoHealt