Effects of extraction pH of chia protein isolates on functional properties

Abstract

The aim of this work was to study the effect of the extraction pH on the functional properties of chia protein isolates (CPI). Samples were named as CPI10 or CPI12, according to their extraction pH, 10 or 12, respectively. Functional properties were significantly modified by the extraction pH. Color properties revealed that CPI12 presented a lower L* (47.8 ± 0.9 for CPI10 and 30 ± 1 for CPI12). Besides, a higher b* value was obtained for CPI12 (7.0 ± 0.3 for CPI12 and 5.6 ± 0.7 for CPI10), as a result of a higher ash content. CPI12 showed a higher WAC probably due to a higher exposure of polar amino acids (4.4 ± 0.1 g/g and 6.0 ± 0.2 g/g), whereas CPI10 showed a higher ability to bind oil (7.1 ± 0.2 g/g and 6.1 ± 0.2 g/g for CPI10 and CPI12, respectively). CPI10 proved more appropriate as an emulsion stabilizer than CPI12, which could be due to its higher surface hydrophobicity, protein solubility and negative net charge. The d4,3 (μm) was 29.5 ± 0.4 and 20.4 ± 0.3 in emulsions stabilized with CPI12 and CPI10, respectively. Although both isolates underwent heat gelation, they exhibited a weak gel behavior. Overall, CPI10 may be more suitable for the food industry as a meat replacer or extender.