Effect of konjac glucomannan on gelling and digestive properties of myofibrillar protein in Litopenaeus vannamei based on molecular docking

Konjac glucomannan (KGM) is commonly used as a texture enhancer due to its distinctive gelling properties. This study aimed to investigate the changes in gelling and digestive properties of myofibrillar protein (MP) in Litopenaeus vannamei when modified with varying KGM (1/40, 1/20, and 1/10 of the MP weight, respectively). The physicochemical properties of KGM-modified MP including secondary and tertiary structures, emulsibility, particle size, and protein aggregation were significantly affected. In contrast, the KGM treatment group (1/20 of MP weight, MK20) exhibited the highest storage modulus, loss modulus, and thermal stability of MP. This resulted in an improvement in the water holding capacity, the stability of the three-dimensional space network, and the strength of the heat-induced MP gels. In addition, the digestion behavior of MP gel could be regulated by modifying MP with KGM. When compared to control sample, the digestion rate and hydrolysis degree of MK20 increased by 16.63% and 1.32 times, respectively. However, it should be noted that excessive KGM could result in the formation of a viscous hydrogel that permeates with MP, causing a loose degradation structure and reducing sensitivity to digestive enzymes. The molecular docking results indicated that KGM interacted with MP through hydrogen bonding, primarily relying on its hydroxyl group. This interaction disrupted the α-spiral structure of MP and promoted the expansion of its structure, and ultimately affected the physicochemical properties of MP and its heat-induced gel.