Development of a low-salt soy sauce with enhanced flavor and functionality with soy residue and Tenebrio molitor larvae powder

Abstract

We developed a low-salt soy sauce from soy residue and T. molitor larvae powder. The salinity of low-salt soy sauce replaced by okara (LSO), T. molitor larvae powder (LST), or both okara and T. molitor larvae powder (LSOT) ranged between 9.87 and 12.47% with a pH of 5.4-6.3. LSO exhibited lower acidity (0.58) than LST (1.27) and LSOT (1.34). LSOT showed the highest protease activity, total nitrogen, and amino nitrogen content among the soy sauces. Glutamic acid was 10 times higher in LST and LSOT than in LSO. LST and LSOT had twice higher antioxidant capacities, whereas LSO had twice higher ACE inhibitory activity than low-salt or regular high-salt soy sauces. T. molitor larvae powder supplementation in soy sauce fermentation led to a significant increase in overall quality. Moreover, the synergistic effect of the mixture of okara and T. molitor larvae powder improved the functionality of low-salt soy sauce. Practical applications Soy sauce produced from fermented soybeans is widely used as a seasoning because of its unique flavor. However, it is classified as a high-salt seasoning. Okara is a soy product-derived waste material that is rich in dietary fibers, and Tenebrio molitor has become an alternative protein source with a low impact on the environment. Fermentation is a promising technique to approach consumers and gain acceptance of insect ingredients in food products, as well as to improve functionality. Using okara and T. molitor larvae powder for soy sauce production results in a savory low-salt product, which is expected to lower the risk of vascular disease and has high antioxidant capacities.