Consequences of heating under alkaline pH alone or in the presence of maltodextrin on solubility, emulsifying and foaming properties of faba bean protein

Faba bean (Vicia faba L.) has attracted interest as a source of plant proteins due to the high protein content, easy cultivation, and the excellent nitrogen-fixing capacity. However, application of faba bean protein is still negligible in food products primarily due to its low solubility and functionality. In the current study, impact of heating under alkaline pH (11.0) alone or in the presence of maltodextrin on physicochemical characteristics, solubility, emulsifying activity, and foaming properties of faba bean protein isolate powder (FBP) from a pilot processing was investigated. Heating at alkaline pH irreversibly disrupted the original large micron-sized aggregates in untreated FBP, along with formation of the smaller aggregates with higher surface hydrophobicity. In the presence of maltodextrin, a FBP-maltodextrin conjugate with high degree of glycation was formed by the heating at alkaline pH. The heating under alkaline pH either in the presence and absence of maltodextrin significantly improved the protein solubility from 43, 14, and 35% at pH 3.0, 6.0, and 7.0, respectively to more than 90%. Compared to the untreated FBP, the FBP-maltodextrin sample heated at pH 11.0 could produce emulsions that were stable against flocculation and phase separation for 15 days storage at pH 6–7 or in the presence of salt. Moreover, foaming capacity and stability of the FBP and FBP-maltodextrin samples heated at pH 11.0 was greatly improved. This study suggested that heating under alkaline pH has a great potential to improve the functional properties of FBP to enable its wide applications in food area.