Impact of soaking and cooking on in-vitro digestibility of chickpea proteins

Cooking pulses involves simultaneous heat and water transfer, which modifies seed components and affects starch and protein digestibility. This study evaluated the impact of soaking and cooking on the in-vitro protein digestibility (IVPD) of chickpeas. Grains were soaked at 30 °C for 0, 45, 90, or 360 min to assess water transfer effects, or cooked in water at 85 °C for 300 min, at 100 °C for 180 min, or at 100 °C for 90 min followed by 113 °C for 40 min to isolate heat transfer effects at comparable final water contents. Cooked samples reached the same final water content as hydrated grains but exhibited different degrees of starch gelatinization and vicilin and legumin denaturation. Water transfer alone did not alter IVPD (≈84 %), whereas cooking increased protein digestibility by 3–4 %. This improvement was associated with an 87 % reduction in trypsin inhibitor activity and unfolding. Increasing cooking temperature further enhanced protein denaturation but did not improve IVPD, suggesting aggregation. PDCAAS values remained high and unchanged, indicating preserved protein quality. Because the cultivar studied exhibited low initial trypsin inhibitor activity, larger digestibility improvements may be expected for cultivars with higher inhibitor levels.