Table 1.

The characteristics, nutritional value, and health benefits of fermented soy foods.

Product	Fermentation Processes	Microorganism Involved in Fermentation	Nutritional Value	Health Benefits	Ref.
Tempe	It is made in two steps: bacterial fermentation of cooked dehulled soybeans followed by solid-state fermentation by the mold	Rhizopus oligosporus, Rhizopus oryzae	High in protein Rich source of probiotics, phytonutrients, and isoflavones	Inhibition of free radicals production, antioxidant activity Cognitive improvement Modulation of gut microbiota in human toward a healthier profile	[162,163,164,165,166]
Natto (Itohiki)	Natto is produced using soaked and cooked soybeans fermented by bacteria for 24 h at 40 °C	Bacillus natto	Lower amount of sugar Increased proteins hydrolysis and digestibility High amount of fiber and vitamin K, free isoflavones, and levan	Prevention from blood clot formation by the production of nattokinase, and therefore prevention from cardiovascular diseases Antioxidant and antihypertensive activity Reduction in bone loss and promotion of bone formation in postmenopausal women Gut microbiota modulation	[165,167,168,169,170,171],
Douchi	Soaked and steamed soybeans are incubated with Aspergillus spp. for 3–4 days at 30 °C, then after washing and adding salt, water, and ginger spices, the mixture is incubated for 15 days at 37 °C	Aspergullus oryzae	High in protein, peptides, free and essential amino acids and organic acids	Antioxidative, antihypertensive, and antidiabetic activity	[172,173,174]
Hawaijar	Washed, soaked, and boiled (for 2–3 h) soybeans are loosely packed in the bamboo basket lined with leaves and kept for 2–3 days to be fermented	Bacillus subtilus, Bacillus licheniformis, Bacillus cereus, and a smaller number of Staphylococcus spp.	A rich source of protein, essential amino acids, and peptides High fiber content	Radical scavenging, antioxidant and antidiabetic activities	[175,176,177]
Miso	Miso is made by enzymatic degradation of cooked soybeans with molded rice, wheat, orbarley, and a small amount of water in the presence of 8–12% salt	Aspergullus oryzae, Pediococcus halophilus	Rich source of different vitamins, including vitamins B, K, E, folic acid and also minerals, amino acids	Protection against hypertension, stroke, and some types of cancer Antiobesity, antidiabetic immunomodulatory, and antioxidant activities Gut microbiota modulation	[165,169,178,179]