Evaluation of γ- aminobutyric acid, phytate and antioxidant activity of tempeh-like fermented oats (Avena sativa L.) prepared with different filamentous fungi

Abstract

Tempeh is a popular traditional fermented food in Asia. Many tempeh-like foods are made from cereal grains. However, the information of γ-aminobutyric acid (GABA) accumulation in those tempeh-like cereal grains during fermentation is lacking. Meanwhile, little information is available on the anti-nutrient contents and antioxidant activity of tempeh-like fermented oats. The aim of the present work was to study the changes of GABA, phytate, natural antioxidants and antioxidant activity of tempeh-like fermented oats. As fermentation time progressed, the GABA, total phenolics content (TPC) and flavonoids increased rapidly. The Aspergillus oryzae-fermented oats had the highest GABA, whereas Rhizopus oryzae-fermented oats had the highest TPC. Phytate, an anti-nutrient component, was dramatically reduced in the fermented oats, especially those by A. oryzae (reduced by about 63 %). The antioxidant activities of fermented oats were also significantly enhanced after 72 h fermentation (p < 0.05). This study demonstrated that oats fermented by generally recognized as safe (GRAS) fungi can be recommended as tempeh-like functional foods with higher GABA, more natural antioxidants and lower phytate compared with native oats.

Myo-inositol phosphates profile of buckwheat and quinoa seeds: Effects of hydrothermal processing and solid-state fermentation with Rhizopus oligosporus

“…Solid-state fermentation of legume seeds and cereal grains with Rhizopus oligosporus (tempe process) and Aspergillus oryzae (koji process) is commonly applied, especially in Asia, to improve the nutritional characteristics of foods [15][16][17][18] . As proven by our earlier research, tempe-type products of advantageous bioactive, nutritional and sensory properties may also be successfully obtained from quinoa seeds and fair buckwheat groats [19,20] .…”

Antioxidant activity of raw, cooked and Rhizopus oligosporus fermented beans of Canavalia of coastal sand dunes of Southwest India

“…Rhizopus oligosporus is commonly employed to produce fermented oriental foods as it is Generally Regarded As Safe (GRAS). Besides enhancement of nutritional quality, solid-state fermented foods showed enhanced antioxidant properties (Sheih et al 2000;Starzyńska-Janiszewska et al 2008;Cai et al 2012). There is no literature on impact of fungal fermentation on the nutritional and bioactive compounds of Canavalia of coastal sand dunes.…”

Harnessing Microbes for Sustainable Development: Food Fermentation as a Tool for Improving the Nutritional Quality of Alternative Protein Sources

“…In addition, tempeh-type oat fermentation with filamentous fungi (Aspergillus oryzae var. effuses 3.2825, A. oryzae 3.5232 or Rhizopus oryzae 3.2751), for example, reduces phytic acid content within 72 h, which may enhance nutrient availability and protein solubility [120]. Furthermore, oat bran fermentation with baker's yeast for 2−6 h at 30 • C has been found to reduce the phytic acid content, with 6-h incubation being the most effective [121].…”