Food Biophysics of Protein Gels: A Challenge of Nano and Macroscopic Proportions

Abstract

Aggregation and gelation of proteins are key reactions used to generate food texture. Heat-induced gelation of globular proteins produces two general types of gels designated as fine-stranded and particulate. Fine-stranded gels are formed from denatured proteins that aggregate into curved, flexible strands (pH > pI) or rigid, linear fibrils (pH pI breakdown into large, inhomogeneous particles that have irregular shapes and do not form a cohesive mass or stick to the teeth during chewing. In contrast, particulate gels are formed from proteins with a lower degree of unfolding that aggregate into large particles. Particulate gels break down rapidly into a homogeneous distribution of small particles forming a cohesive mass that adheres to teeth during chewing. This review discusses the mechanisms related to the formation and breakdown of fine-stranded and particulate gels. Although there has been extensive research on gel formation, understanding gel breakdown based on mechanical (rheological and fracture properties) and sensory testing is limited. Further research is required to understand how the nanostructure of a gel network translates into the complex fracture pattern seen when evaluating the macroscopic property of food texture.