Effects of Germination on the Nutritional Properties, Phenolic Profiles, and Antioxidant Activities of Buckwheat

Abstract

Germination is considered to be an effective process for improving the nutritional quality and functionality of cereals. In this study, changes of nutritional ingredients, antinutritional components, chemical composition, and antioxidant activities of buckwheat seeds over 72 h of germination were investigated, and the reasons for these changes are discussed. With the prolonged germination time, the contents of crude protein, reducing sugar, total phenolics, total flavonoids, and condensed tannins increased significantly, while the levels of crude fat, phytic acid, and the activity of trypsin inhibitor decreased. Phenolic compounds, such as rutin, vitexin, isovitexin, orientin, isoorientin, chlorogenic acid, trans-3-hydroxycinnamic acid, and p-hydroxybenzoic acid increased significantly during the germination process, which may be due to the activation of phenylalanine ammonialyase. The improvement of flavonoids led to significant enhancement of the antioxidant activities of germinated buckwheat. Germinated buckwheat had better nutritional value and antioxidant activities than ungerminated buckwheat, and it represented an excellent natural source of flavonoids and phenolic compounds, especially rutin and C-glycosylflavones. Therefore, germinated buckwheat could be used as a promising functional food for health promotion.

Fermentation and germination improve nutritional value of cereals and legumes through activation of endogenous enzymes

“…Phytochemicals are important plant secondary metabolic products produced in phenylpropanoid biosynthesis and shikimate pathways during the growth of plants (Zhang, Xu, Gao, Huang, & Yang, 2015). During growth, L‐phenylalanine, under the effect of phenylalanine ammonia lyase (PAL) catalyzation, changes into cinnamic acid.…”

“…These can later be converted into tannins, flavonoids, lignins, and other compounds. Advances in research have revealed importance of these phytonutrients to human health by virtue of their antioxidant properties (Zhang et al., 2015), cholesterol‐lowering effect (Golzarand, Mirmiran, Bahadoran, Alamdari, & Azizi, 2014; Gunness & Gidley, 2010), and reduction in the production of pro‐inflammatory cytokines and immunosuppressive cells (Lesinski et al., 2015). Due to the complexity of studying phytochemicals, few studies have focused on studying the effects of traditional processing techniques due to limited capacity in most laboratory studying these traditional methods.…”

“…Germination and malting facilitate the enzymatic breakdown of carbohydrates into simple sugars through activation of endogenous enzymes such as α‐amylase thereby improving digestibility (Oghbaei & Prakash, 2016) as a result of degradation of starch to provide energy for the seed development (Zhang et al., 2015). Germinating white sorghum for 24 and 36 hr resulted into a decrease in carbohydrates and increase in simple sugars (Obizoba & Atii, 1991).…”

“…The content of the reducing sugars in cereals and legumes was not significantly affected during the first 12 hr of germination. However, after 12 hr the content of reducing sugars increased 20 times suggesting increased enzymatic hydrolysis of starch (Zhang et al., 2015). This happens due to the action of α‐amylase which is activated during germination leading to hydrolysis of carbohydrates, change of taste, and digestibility of the carbohydrates (Zhang et al., 2015).…”

“…However, after 12 hr the content of reducing sugars increased 20 times suggesting increased enzymatic hydrolysis of starch (Zhang et al., 2015). This happens due to the action of α‐amylase which is activated during germination leading to hydrolysis of carbohydrates, change of taste, and digestibility of the carbohydrates (Zhang et al., 2015). Mbithi‐Mwikya, Camp, Yiru, and Huyghebaert (2000) noted a similar trend in germinated seeds.…”