Unveiling the aroma profile of anhydrous milk fat: Insights into key odorants during biocatalysis by aroma extract dilution analysis, aroma recombination, and omission experiment

Determination and verification of the key aroma compounds of anhydrous milk fat (AMF) were conducted during biocatalysis at different times using commercial immobilized Lipozyme RMC from Rhizomucor miehei and Lipozyme TL-IM from Thermomyces lanuginosus. The analysis techniques employed included headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) coupled with olfactory port, aroma extract dilution analysis (AEDA), odor activity values (OAV), aroma recombination model, and omission experiments. A total of 17 main odorants were identified and quantified in AMF, and characterized by flavor dilution factors ranging from 4 to 128. Among them, butanoic acid, methyl octanoate, hexanoic acid, methyl butanoate, and methyl decanoate revealed the highest flavor dilution. These aroma-active compounds were confirmed as important odorants based on their OAVs ≥ 1. Furthermore, the omission and recombination model sensory experiments successfully identified 12 key odorants including butanoic acid, methyl octanoate, hexanoic acid, octanoic acid, methyl hexanoate, and methyl butanoate in AMF catalyzed with Lipozyme RMC. Overall, this research provides valuable insights into the enzymatic modification of AMF and its impact on flavor modulation in dairy products.