Tannins in Foods: Nutritional Implications and Processing Effects of Hydrothermal Techniques on Underutilized Hard-to-Cook Legume Seeds－A Review

Abstract

Tannins, water-soluble phenolic compounds, have been reported to have the ability to form complexes with nutritionally important nutrients such as protein and mineral elements thereby making them unavailable for absorption and utilization. Toxicity of tannin has been demonstrated in experimental animals although no deleterious effect of ingestion of legume tannin on human physiology has been reported. This report highlights the processing effects of soaking and hydrothermal techniques on some underutilised hard-to-cook legume crops and the importance of tannin in legume nutrition. Soaking and hydrothermal processing reduce the tannin content of processed legume seeds and hence improve the availability of protein and mineral elements. In view of the recent findings of the health benefits, classification of tannin which is traditionally regarded as an antinutrient should be reconsidered. Provision of these information will enhance knowledge of legume nutrition and economic utility. Increasing consumption of underutilized nutritionally important legume seeds, it is hoped, will alleviate the problem of protein energy malnutrition in many developing nations.

Role of Condensed Tannins in the Antioxidant Activity of Seeds of Cola nitida (Vent.) Schott & Endl. (Malvaceae)

“…Certain nanoparticles of chemical antioxidants could cross the placental barrier and cause teratogenic effects [20]. However, condensed tannins have the disadvantage of binding to proteins, carbohydrates and mineral elements, thus reducing nutritional value of certain nutrients [21].…”

Comparative Analyses of Impact of Varying Germination Periods on Malt Quality and Wort Characteristics of Sorghum Bicolor (L) Moench and Sorghum Vulgare Varieties

“…However, it is unclear why a further tannin decrease was observed in wort, perhaps the mashing pH, temperature and enzymic activities may be contributory (Ojo, 2022).…”

Effect of Addition Fermented Cabbage Extract on Antioxidant Activity and Antinutritional Compounds of Foxtail Millet Flour

“…Tannins are polyphenolic compounds with unique characteristics. Tannins have higher antioxidant properties than vitamins E and C but are also anti-nutritional because they can reduce the digestibility of carbohydrates and proteins (Ojo, 2022). Tannin levels in FMF without fermentation reached 2.71 mg/g (Figure 3), lower than the report of Shejawale et al (2016) which ranged from 3.24 to 4.13 mg/g.…”