Polyphenols in whole rice grain: Genetic diversity and health benefits

The impact of cooking method on the phenolic composition, total antioxidant activity and starch digestibility of rice (Oryza sativa L.)

“…To the best of our knowledge, the presence of isovanillic acid in rice grains have not been reported before. Moreover, protocatechuic acid, the most abundant free phenolic acid found in pigmented rice (red and black varieties) (Shao & Bao, ), was not detected in the present study of polished rice samples using the HPLC‐DAD, but it can be quantified in whole grain brown rice (8.7 mg/kg DW). With the exception of both these acids, the other phenolic compounds constituted a medium portion (2.0–9.8%) of the phenolic profile of analyzed rice samples.…”

“…The levels of p ‐hydroxybenzoic and syringic acids, dominant components of phenolic profile of the jasmine and basmati rice grains, are higher than that reported in other studies of nonpigmented (white) varieties (Shao, Xu, Sun, Bao, & Beta, ; Tian et al, ; Vichapong et al, ; Zaupa et al, ; Zhou et al, ). The obtained results showed that vanillic acid contributing up to 12.6% of total phenolics was also found at higher concentrations compared to previous literature reports on white (0.3–8.5 mg/kg DW) and colored rice grains (0.4–15.0 mg/kg DW) (Shao & Bao, ; Tian et al, ; Vichapong et al, ; Zhou et al, ).…”

“…For that reason, ferulic acid was the most predominant compound in the rice grain samples evaluated. In several previous studies, ferulic acid was also found to be the most abundant phenolic acid determined in all varieties of rice with the concentration ranging from 3.4 to 84.0 and from 12.4 to 362.0 mg/kg DW in non‐pigmented and pigmented rice grains, respectively (Shao & Bao, ; Tian, Nakamura, & Kayahara, ; Zaupa et al, ; Zhou et al, ).…”

“…Meanwhile, the study of Italian white rice variety showed a significantly higher total content of both phenolic acids (∼5–10‐fold), including free and bound forms (Zaupa et al, ). These comparative data on ferulic and p ‐coumaric acids, which serve as main substrates to form the basic skeleton of all flavonoid derivatives in rice grain (Shao & Bao, ), indicated that their contents in white and brown rice, not surprisingly, depend strongly on the variety, geographical origin, type of processing as well as extraction method used. The levels of p ‐hydroxybenzoic and syringic acids, dominant components of phenolic profile of the jasmine and basmati rice grains, are higher than that reported in other studies of nonpigmented (white) varieties (Shao, Xu, Sun, Bao, & Beta, ; Tian et al, ; Vichapong et al, ; Zaupa et al, ; Zhou et al, ).…”

“…Phenolic compounds display many beneficial effects on human health. Scientific and epidemiological studies of bioactive properties of whole grain rice and dietary rice bran showed that their phytochemicals exhibit antioxidant, anti‐infladigesmmatory (Shao & Bao, ), antihypertensive (Massaretto, Madureira Alves, Mussi de Mira, Karaoglanovic Carmona, & Lanfer Marquez, ) and chemopreventive effects against several types of cancer, such as colon, breast, lung and liver cancer (Dipti et al, ; Henderson et al, ; Mannan, Sarker, Kabir, Rahman, & Alam, ). Moreover, the polyphenols distributed in bran layer of rice may reduce the risk of some chronic diseases including cardiovascular disorders, type II diabetes and obesity, as well as play an important role in the inhibition of cholesterol oxidation (Dipti et al, ; Shao & Bao, ).…”