Effect of pH on the thermal gelation of carob protein isolate

BENGOECHEA, C.; MOLINA ORTIZ, S.E.; GUERRERO, A.; PUPPO, M.C.

JOURNAL OF FOOD SCIENCE AND TECHNOLOGY-MYSORE

ASSOC FOOD SCIENT TECHN INDIA

Año: 2017 vol. 54 p. 153 - 163

0022-1155

Carob seed is a source of a protein called caroubin that may be obtained as a by-product of the locust bean gum industry, being traditionally used as sweetener. The specific aim of this work was to study the capability of a carob protein isolate (CPI) to produce self-supporting gels when subjected to a thermal treatment. CPI aqueous dispersions (10, 20 and 30 wt.% protein basis) at three different pH values (2, 6 and 10) were subjected to a heating/cooling process (95ºC-30 min/4ºC-24 h) leading to the formation of self-supporting gels. Those gels were characterized as means of their dynamic rheological properties; water holding capacity (WHC); textural properties; extractability in different media; scanning electron microscopy (SEM); and SDS-PAGE profiles of the soluble proteins. From results, it was found that self-supporting CPI gels were only obtained at concentrations higher than 20 wt.%, being favoured at extreme pH values, especially at alkaline pH. At pH 10, gels with higher dynamic elastic and hardness properties and appropriate WHC were formed due to the promotion of disulphide bonds formation. Thus, if higher rheological properties and hardness are pursued for thermally treated CPI gels, alkaline pH conditions that favour hydrophobic interactions and disulphide bonding should be selected.