Identification\nof Lactose-Derived α‑Dicarbonyl\nCompounds in Dairy Products and Elucidation of Their Formation Mechanism

α-Dicarbonyl compounds (α-DCs) generated\nfrom carbohydrates\nplay a key role in food quality and safety as precursors. Lactose\ncontributes to α-DCs generation in dairy products; however,\nα-DCs with intact lactose carbons have not been investigated so far. This study aimed to\nidentify lactose-derived α-DCs, clarify the mechanism of its\nformation using model incubations, and investigate the distribution\nand contents of α-DCs in dairy products. From the heated lactose\nand lysine solution, four new α-DCs derivatives were isolated\nby column chromatography and preparative HPLC and identified as lactosone,\n1-deoxylactosone (1-DL) and its epimer, and 1,5-dideoxylactoson-4-ene\n(1,5-DDLE) by MS and NMR analyses. 1-DL, 1-DL epimer, and 1,5-DDLE\nwere specifically formed from Amadori compounds of lactose and could\nbe indicators of lactose-associated Maillard reaction. These α-DCs\nwere abundantly contained in thermally processed dairy products, especially\ninfant formulas and whey protein, and affected by ingredients and\nmanufacturing process.