Fatty Acids and Volatile Flavor Components of Adipose Tissue from Local Tibetan Sheep in Qinghai with Dietary Supplementation of Palm Kernel Meal (PKM)

Abstract

Substituting traditional protein feed with palm kernel meal (PKM) in the diet of Tibetan sheep can be a cost-effective feeding strategy. To determine the impact of PKM on flavor development in different adipose tissues of Tibetan sheep, subjects were fed with 15% and 18% of PKM, while the control group received no PKM. The fatty acids and volatile compounds in the samples were then analyzed by GC-MS and HS-GC-IMS. Adding PKM to the diet significantly increased the C12:0, C14:0, C16:0 and C18:1N9 content in adipose tissues compared with the control, and most of these were associated with flavor formation (p < 0.05). The flavor compounds in the adipose tissues predominantly consisted of alcohols, ketones, acids and aldehydes. In particular, including PKM in the diet increased the proportion of ketones but decreased the proportion of alcohols, acids and aldehydes in subcutaneous and tail fat. Specifically, the proportion of acetone, acetoin monomer, 2,3-butanedione, 2-butanone monomer, 2-methyl-2-propanol, 2-methyl-2-propanol and methyl acetate increased significantly in the subcutaneous and tail fat (p < 0.05), while that of ethanol, 1-propanol monomer, butanol monomer, acetic acid monomer and acetic acid monomer decreased. Intermuscular fat exhibited variable results, mainly because the addition of PKM resulted in higher proportions of alcohols, including ethanol, 1-propanol and butanol monomer, especially at 15% PKM. In summary, the addition of PKM improved the flavor of Tibetan sheep fat and increased the amount of favorable volatile flavor compounds. This study can serve as reference for understanding the effects of dietary PKM on the adipose tissue flavor profile of Tibetan sheep.