Heat-Induced Gelation of Chickpea and Faba Bean Flour Ingredients

Abstract

This study aimed to investigate the gelling behavior of faba bean (FB) and chickpea (CP) flour between 10 and 20% (w/w) concentration at pH 3.0, 5.0, and 7.0. Both sources formed at pH 3.0 and 5.0 self-standing gels with 12% (w/w) of flour, while 16% (w/w) of flour was required to obtain a gel at pH 7.0. During gelling between 40 and 70 °C, a sharp increase of the elastic modulus G' was observed in both flours, mainly due to water absorption and swelling of the starch, one of the major constituents in the ingredients. Increasing the temperature at 95 °C, G' increased due to the denaturation of globulins and therefore the exposure of their internal part, which allowed more hydrophobic interactions and the formation of the gel. After cooling, both FB and CP gels displayed a solid-like behavior (tan δ ranging between 0.11 and 0.18) with G' values at pH 3.0 and 5.0 significantly (p < 0.05) higher than those at pH 7.0, due to the lower electrostatic repulsions at pHs far from the isoelectric point. The rheological properties were supported by the water binding capacity values, confirming the better gels' strength described by rheological analysis. These results will enhance our understanding of the role of legume flours in formulating innovative and sustainable food products as alternatives to animal ones.

Keywords: chickpeas; faba bean; food structure; legumes; rheological properties; starch-protein interaction.

Figure 1

Differential scanning calorimetry thermogram of hydrated faba bean () and chickpeas () flours.

Figure 2

Sol-gel transition diagram of faba bean (FB) and chickpeas (CP) flours at 10, 12, 14, 16, 18, 20% (w/w) and pH 3.0, 5.0, and 7.0 Symbol indicates a gel-like structure and symbol indicates a liquid or aggregate-like structure.

Figure 3

Water holding capacity of faba beans (FB) () and chickpeas (CP) () gels at 10, 12, and 14% at pH 3.0 and 5.0, and 14, 16, and 18% at pH 7.0. Different lowercase (a, b, c) (FB) and uppercase (A, B, C) (CP) letters indicate significant (p < 0.05) differences among the same source and same pH. Differences between sources (FB and CP) within the same pH and concentration are indicated with *.

Figure 4

Temperature, frequency, and strain amplitude sweeps of faba bean (FB) and chickpea (CP) gels at pH 3.0, 5.0, 7.0 at the minimum gelling concentration (MGC). G′: black point symbols, G″: grey triangle symbols.

Figure 4

Temperature, frequency, and strain amplitude sweeps of faba bean (FB) and chickpea (CP) gels at pH 3.0, 5.0, 7.0 at the minimum gelling concentration (MGC). G′: black point symbols, G″: grey triangle symbols.