Soy-Based Tempeh as a Functional Food: Evidence for Human Health and Future Perspective

Tempeh is an Indonesian traditional food made from fermented soybeans, which offers wide culinary use in East Asian countries. Similar to all fermented foods, its preparation offers the purpose of food preservation. However, preclinical studies have highlighted that microbial action leads to a modification in the nutritional composition of the food's matrix. Although there is a wide availability of data on the beneficial effect of soy, tempeh remains relatively unexplored, perhaps due to its limited diffusion in the world, which limits its research availability. However, available data suggest that tempeh may confer beneficial health effects due to the high bioavailability of nutrients and phytochemicals, showing ameliorative action on oxidative stress, glycaemic control, and blood lipid levels. Furthermore, the high biological value of tempeh means it can be used to optimize protein and caloric intake in athletes, vegetarians, and children. Moreover, the microbial fermentation used in the production of tempeh, in addition to improving the bioavailability of minerals, proteins, fibre, vitamins, and isoflavones, produces biopeptides whose biological effect is currently of great interest. Tempeh can be employed in traditional preparations as well as second-generation foods, such as plant-based meat substitutes, to provide functional and nutritional properties and a higher eco-friendly option compared to animal foods. This review aims to provide an overview of tempeh's properties, regarding human data and future research perspectives.