Changes of Unique Flavor Substances and Metabolic Pathway Brought by Lacticaseibacillus rhamnosus WH. FH-19 Fermented Milk during Fermentation and Storage Stage: HS-SPME-GC-MS and HPLC-MS-based Analysis

We evaluated the changes in volatile and nonvolatile flavor substances after fermented milk was fermented by Lacticaseibacillus rhamnosus WH. FH-19 using Headspace Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) and High-Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS). The results have shown that the addition of L. rhamnosus WH. FH-19 can increase the contents of acetoin and 2-nonanone which can give fermented milk cream and cheese flavor, and significantly enrich amino acid metabolism and carbon metabolism. The fermentation of L. rhamnosus WH. FH-19 increased the contents of L-glutamic acid, taurine, stachyose, erythritol, L-rhamnose, retinol, pantothenic acid and 19 oligopeptides in fermented milk, and endowed fermented milk with good flavor, quality and antioxidant capacity. The results presented that L. rhamnosus WH. FH-19 can increase the content of flavor substances, promote the metabolism of amino acids and carbohydrates in fermented milk, and produce more antioxidant metabolites, which had the potential as a starter of fermented milk.