Bioaccessibility of Polyphenols from Wheat (Triticum aestivum), Sorghum (Sorghum bicolor), Green Gram (Vigna radiata), and Chickpea (Cicer arietinum) as Influenced by Domestic Food Processing.

Cereals (wheat and sorghum) and legumes (green gram and chickpea) commonly consumed in Asia and Africa
were evaluated for polyphenolic content. Bioaccessibility of polyphenols from these grains as influenced by domestic processing
was also estimated. Total polyphenol content of wheat and sorghum was 1.20 and 1.12 mg/g respectively, which was increased
by 49% and 20% respectively, on roasting. In contrast, a significant reduction of the same was observed in both the cereals after
pressure-cooking, open-pan boiling, and microwave heating. Total flavonoids, which was 0.89 mg/g in native sorghum, reduced
drastically after processing. Tannin content of both the cereals significantly increased on sprouting as well as roasting. Total
polyphenol content reduced by 31% on sprouting but increased to 24% on roasting in green gram. Pressure-cooking (53%),
open-pan boiling (64%), and microwave heating (>2-fold increase) significantly increased total polyphenol content in chickpea,
while drastic reduction was observed in the total flavonoid content. Bioaccessible total polyphenols from these grains were in the
following order: green gram > chickpea > wheat > sorghum. Domestic processing of these grains had minimal/no effect on the
bioaccessible total flavonoid content. Not all the phenolic compounds present in them were bioaccessible. Concentration of
bioaccessible phenolic compounds increased especially on sprouting and roasting of these grains, except chickpea, where
sprouting significantly reduced the same (476 to 264 μg/g). Microwave heating significantly enhanced the concentration of
bioaccessible polyphenols especially from chickpea. Thus, sprouting and roasting provided more bioaccessible polyphenols from
the cereals and legumes studied.