Gelation potential of oat protein isolate: Influence of extraction method, gelling conditions, and enzymatic modification

The poor technological functionality of oat protein presents a challenge in food applications. This study investigated the effect of extraction method, gelling conditions (pH and NaCl concentration), and enzymatic modification on heat-induced gelation of oat protein isolate (OPI). Fairly strong gels (G′ = 5000 Pa, tan δ = 0.26) were formed from OPI, but gelation was highly sensitive to pH and NaCl concentration. Extraction at pH ∼10 negatively affected the gelation properties compared to extraction at pH 8. Partial hydrolysis with alcalase, bromelain, or papain increased the solubility of OPI but was detrimental to gelation, leading to liquid expulsion from the gel. After enzymatic deamidation with protein glutaminase, up to 87 % solubility of OPI at pH 7 was achieved, and it formed soft, elastic, and slightly translucent gels (G′ = 1100 Pa, tan δ = 0.21). The extraction process and modifications of oat proteins have a great impact on their techno-functionality and need optimization for food applications. • Oat protein solubility was increased by mild hydrolysis and enzymatic deamidation. • Protein extraction at pH 8 resulted in improved gelation compared to pH 10. • NaCl had a pH-dependent effect on gelation of oat protein. • Enzymatic deamidation resulted in soft, homogeneous, and translucent gels.