Low-pH-thermal treatments modulate lectin conformational structure and starch digestion in intact pulse cells.

White kidney bean (WKB) lectins are antinutritional proteins that may cause adverse physiological effects when beans are inadequately processed. In this study, WKB seeds were subjected to acidic soaking (pH 1-5) followed by hydrothermal treatments (60 °C and 100 °C) to obtain intact cotyledon cells. Processing-induced changes in lectin structure, hemagglutination activity, immunoreactivity, starch crystallinity, and in vitro starch digestibility were systematically evaluated. Strongly acidic (pH 1, 60 °C) and hydrothermal (100 °C) treatments markedly reduced lectin content (4.2 and 4.3 mg/g), hemagglutination activity (95.7 and 176.2 HU/mg), immunoreactivity (38% and 39%), α-helix content (15% and 17%), and lectin thermal stability (Tp = 93.4 °C and 87.1 °C), respectively. These treatments also decreased starch crystallinity (20.5% and 4.2%), gelatinization peak temperature (Tp = 62.5 °C and 47.3 °C), while increased the starch digestion rate (0.0501 and 0.0596 min-1) and extent (64.5% and 69.1%) compared with the mildly acidic treatment (pH 5, 60 °C). Pearson's correlation analysis demonstrated that lectin- and protein-related structural parameters exhibited the strongest negative associations with starch digestibility. Overall, pH-dependent processing altered lectin conformation and stability while enhancing starch bioaccessibility. These findings provide mechanistic insights into the development of safer whole legume-based foods with controlled starch digestibility and potentially glycemic response.