Short communication: Volatiles in microfluidized raw and heat-treated milk

摘要

As innovative processing equipment is introduced tomilk processing, it is essential to determine its effect onmilk aroma, a critical factor in consumer acceptanceof the final dairy product. Microfluidization is knownto cause severe high-pressure homogenization of milkfat and, although severe processing is known to releaseundesired aromas, no information is available on thelevels of the volatile compounds in milk immediatelyafter microfluidization. We hypothesized that microfluidizationwould alter levels of volatile compounds inmilk that may affect aroma. The concentration of 11selected volatile compounds in raw, thermized, pasteurized,and UHT 3.0% fat milk samples were comparedbefore and after microfluidization at 170 MPa and common2-stage homogenization at 15 MPa. Overall, thedifferent milk samples had similar trends in responseto homogenization, although UHT milk started withlower values of nonanoic acid, and acetone and higherlevels of hexanal and heptanol. In many cases, microfluidizationdid not significantly alter volatile levels comparedwith the starting milk. Heptanal was the onlycompound observed to increase in thermized and UHTmilk, whereas nonanoic acid and acetone decreased inraw, thermized, and pasteurized milks and octanoicacid decreased in thermized and UHT milks. The highestlevels of almost all of the volatiles were found in the2-stage homogenized milk. Overall, microfluidizationhad minimal effect on the volatile compound profiles ofmilk, although sensory evaluation is needed to confirmeffects on aroma and flavor.