High-Pressure Processing for the Control of Lipolysis, Volatile Compounds and Off-odours in Raw Milk Cheese

Abstract

Build-up of flavour compounds throughout ripening of raw milk cheeses may result in strong over-ripening notes during refrigerated storage. In order to control the formation of free fatty acids (FFAs) and volatile compounds, and the appearance of off-odours, raw milk cheeses were high-pressure-processed (HPP) 21 or 35 days after manufacture at 400 or 600 MPa. Ripening proceeded at 8 °C until day 60 and, afterwards, cheeses were held at 4 °C until day 240. The effect of HPP on the formation of FFAs and volatile compounds was dependent on pressure level and cheese age at the time of treatment. On day 60, acetic and propionic acids, branched-chain FFAs and short-chain FFAs showed the lowest (p < 0.05) concentrations in cheeses treated at 400 or 600 MPa on day 21, while medium- and long-chain FFAs were at similar levels in all cheeses. HPP influenced significantly (p < 0.05) 84 out of the 94 volatile compounds found in cheese. On day 60, the lowest (p < 0.05) concentrations of acids, alcohols and esters were recorded for cheeses treated at 400 or 600 MPa on day 21, and the lowest (p < 0.05) concentrations of ketones for cheeses treated at 400 MPa on days 21 or 35. On day 240, all HPP cheeses showed lower (p < 0.05) concentrations of aldehydes, esters and, particularly, sulphur compounds than control cheese, which exhibited putrid and rancid off-odours from day 120 onwards. Principal component analysis combining FFAs and volatile compounds discriminated 240-day control cheese from 120-day control cheese and both from the rest of cheeses.