Analysis of quality deterioration of buckwheat hele noodles during freezing storage: oxidation of lipids and proteins

This study systematically investigated the quality changes of buckwheat hele noodles (BHN) during frozen storage at −18 °C for 80 days. Pronounced lipid–protein co-oxidation was observed, characterized by a 71.9% rise in malondialdehyde (MDA) and a 133.2% rise in carbonyl content. Sulfhydryl content showed a continuous decline, while the levels of key unsaturated fatty acids progressively decreased. The activities of lipoxygenase (LOX) and catalase (CAT) gradually diminished, thereby inhibiting enzymatic oxidation but promoting non-enzymatic oxidation. Microscopic analysis revealed a disrupted gluten network with enlarged pores, and the proportion of β-sheet structures in protein secondary structures increased significantly, suggesting enhanced protein aggregation and cross-linking. Flavor analysis indicated that the levels of aldehydes and ketones peaked at 40 days, with 2-nonenal and 1-octen-3-ol identified as the key off-flavor compounds. Correlation analysis confirmed that protein and lipid oxidation were the primary driver of quality deterioration in BHN during frozen storage.