Changes in milk composition of raw, frozen, pasteurized, and freeze-dried jenny milk from a farm-scale dairy.

Jenny milk is prone to deteriorate and is intolerant of freezing and heating. This study compared proximate components, metabolomes, trace elements, and fatty acids (FAs) in raw (RM), frozen (DM), pasteurized (PM), and freeze-dried (FM) jenny milk from milking to final products. Proximate components in RM were lower than the others. Compared with RM, differential metabolites in DM, PM, and FM were associated with protein, amino acid, nucleotide, and carbon metabolism, whereas differences among DM, PM, and FM were related to unsaturated lipid metabolism. Trace element concentrations varied during processing, but toxic elements remained within safety limits in all samples. DM had lower levels of MUFA, n-6 PUFA, and n-9 UFA than FM and PM, while total FA content did not differ among milk types. Therefore, the time between milking and freezing should be shortened and processing technology should be modified to improve the fidelity of jenny milk.