Effects of NaCl, ionic strength and pH on the foaming and gelation of pigeon pea (Cajanus cajan) protein concentrates

Studies were carried out on the effects of pH, ionic strength, sample concentration and added salt (NaCl) concentration on two hydrodynamic properties — gelation capacity and foaming properties of pigeon pea protein concentrates. Results indicate that the protein concentrate has a good gelation capacity with a least gelation concentration of 6% (w/v). Using the least concentration endpoint (LCE) as an index of gelating ability, the gelation capacity of the flour improved in the presence of moderate NaCl concentration and low ionic strength. Acidic and neutral pH also enhanced gelation while alkaline pH decreased it. The foaming capacity of the flour could be improved in a medium of low ionic strength and by increasing the concentration of protein sample as well as by a moderate concentration (0.25% w/v) of NaCl. Better foaming capacity was observed in the acidic region than in the alkaline region. Foams were also observed to be more stable as concentration of NaCl, concentration of protein concentrate and ionic strength increased.