Unlocking the potential of cysteine–xylose Maillard reaction intermediates as natural flavor precursors: a comprehensive study on flavor regulation, storage stability, and antioxidant activity

Abstract

2-Threityl-thiazolidine-4-carboxylic acid (TTCA) and Amadori rearrangement products (ARPs), intermediates of a cysteine–xylose (Cys–Xyl) Maillard reaction system, have been proven to form desirable flavors during thermal processing. The results showed that both TTCA and ARPs revealed excellent environmental stability at low temperatures (≤25 °C), neutral pH (7), and low water activity (0.113). Under storage conditions of 40 °C, pH 9, and 0.843 water activity, the loss rates of TTCA and ARPs reached 7.06% and 12.17%, 11.19% and 21.25% and 35.77% and 60.61%, respectively. Further research found that TTCA and ARP have increased Fe²⁺ chelating ability, ferric ion reducing capacity, and free radical scavenging ability within a concentration range of 0.5 to 3.0 mg mL⁻¹. Additionally, different heat treatment conditions as well as the addition of different exogenous amino acids could regulate the flavor formation profile and characteristics of TTCA, making it suitable for different real food systems and broadening its processing adaptability. In particular, when the pH was increased from 5.5 to 8, the meaty flavor of the system gradually lightened, while flavor characteristics such as popcorn flavor, burnt flavor, and nutty flavor gradually strengthened. This research explored the potential of MRIs, natural flavor precursors, to serve as supplements and partial alternatives to synthetic additives. These findings provide a theoretical basis for developing more sustainable food systems and may help reduce the environmental footprint of food processing.