Combining lipase enzymatic techniques and antioxidants on the flavor of structured lipids (SLs) prepared from goat butter and coconut oil

Enzymatic transesterification can improve the quality of goat butter, however, the high temperature may lead to oil oxidation and produce a bad taste. In this study, goat butter (GB) and coconut oil (CO) were combined to synthesise structural lipids (SLs) by enzymatic transesterification, and antioxidants were added to inhibit oxidation to improve the oils' flavor. The Lipozyme TLIM and tert-butylhydroquinone (TBHQ) were screened for SLs synthesis. The contents of SLs were 56.24% under the optimal conditions of 8 h reaction time, 5°C reaction temperature, 8% enzyme dosage, and 3:1 (w/w) substrate ratio, and the addition of antioxidants had no significant effect on the contents of SLs. It was demonstrated that short-chain fatty acids in the SLs were significantly reduced by 59.2%, and the medium-chain fatty acids were increased by 54.9% compared to GB. One hundred volatile compounds were identified in the lipid samples and classified as (1) long-chain alkane aromatic components and aromatic components, which remarkably decreased by 58.9%, and (2) alcohols, aldehydes, and ketones, which increased by 12.9%, through using solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) and electronic nose. The relative aroma activity value (ROAV) of 9 key volatile aroma components was higher than 1 in the SLs, which greatly contributed to the reduction of goaty flavor and increasing cream flavor. The results suggested that the goaty flavor of GB could be significantly reduced by decreasing the short-chain fatty acids contents in SLs through enzymatic transesterification with CO, while the addition of antioxidants efficiently inhibited excessive lipids oxidation and increased the content of long-chain aldehydes, ketones, and lactones, thus enhancing the cream flavor, which had great potential to be utilized as natural food flavor additives.