Supplemental materials of article (Comparison between the flavor profiles of milk pasteurized by alternating-current high electric field and ultra-high-temperature)

Heat treatment of milk is an indispensable process for ensuring microbiological safety and extending milk’s shelf life. UHT-processed milk results in the development of undesirable cooked flavors. There is an increasing trend toward approaches using multivariate analysis based on the concept that flavor is a composite of volatile compounds. This study evaluated whether alternating-current high electric field (AC-HEF) pasteurization improves the flavor quality of milk compared to conventional ultra-high-temperature (UHT) treatment. Raw milk from a single batch was processed using AC-HEF (115 °C, 20 s) or UHT (135 °C, 2–3 s) treatment. Volatile compounds were profiled using solid-phase microextraction gas chromatography–mass spectrometry with a targeted aroma database (~500 compounds) and gas chromatography–sulfur chemiluminescence detection (GC-SCD) for sulfur-containing volatiles. Sensory evaluation involved a 120-member consumer panel and a trained panel, and differential addition tests were performed for key aroma compounds identified by multivariate analysis. Consumers rated AC-HEF milk higher for its pleasant aroma and aftertaste. Multivariate analysis indicated that hexanal and butyl acetate were characteristic of AC-HEF milk, whereas 1-octen-3-one was more abundant in UHT milk. Spike-in tests showed that the addition of hexanal to UHT milk improved the perception, whereas 1-octen-3-one addition to AC-HEF milk produced undesirable results. GC-SCD confirmed significantly higher levels of carbon disulfide in UHT milk. These results suggest that AC-HEF processing enhances favorable flavor attributes by suppressing off-flavor formation while maintaining the levels of aromatic volatiles. Thus, AC-HEF represents a promising alternative to UHT for producing shelf-stable milk with an improved flavor profile.