The Nutritional Value of Non-Traditional Gluten-Free Flakes and Their Antioxidant Activity

Abstract

Nowadays, there is a growing interest for foods with a lower sugar content and rich in fiber and biologically active substances. The main purpose of this study was to prepare flakes from non-traditional pigmented cereals (Oryza sativa, Chenopodium quinoa, and Eragrostis tef) and to analyze their fibre, sugar, and in vitro digestibility values. Regarding phenolic antioxidants (soluble, soluble conjugated, and insoluble bound fractions), their content and antioxidant activity were measured using spectrophotometry and high performance liquid chromatography (HPLC) methods. Hydrothermally treated grains resulted in flakes with higher total dietary fibre contents (11.1–24.4%), quinoa and teff flakes were rich in maltose (up to 42.0 mg/g). Non-traditional flakes had lower in vitro digestibility, but conversely, they exhibited the highest phenolic contents corresponding with the highest antioxidant activity values (up to 2.33 mg Gallic acid equivalent/g of total phenolic content and 1.59 mg Trolox equivalent/g for 2,2-diphenyl-1-picrylhydrazyl (DPPH) in case of brown teff). Among free phenolics, the main contributors to an antioxidant activity were p-coumaric, o-coumaric, and gallic acids (r > 0.8186); among the soluble conjugated fractions, they were epigallocatechin, epicatechin, caffeic, and vanillic acids (r > 0.5935); while caffeic, protocatechuic, and ferulic acids (r > 0.5751) were the main contributors among the insoluble bound phenolics.

Effect of cellulase on antioxidant activity and flavor of Rosa roxburghii Tratt

“…From 4 % to 57 % of the phenolic compounds found in fruits and vegetables are strongly linked to dietary fiber through either covalent bonds, hydrophobic bonds, or hydrogen interactions ( Huang et al, 2022 ). Šťastná et al have reported that caffeic acid, protocatechuic acid, gallic acid, ferulic acid, epigallocatechin and quercetin were the major contributors to the antioxidant activity of the insoluble bound fractions ( Šťastná, Mrázková, Sumczynski, Cındık, & Yalçın, 2019 ). Dansi Huang et al also found that RRT pomace is rich in gallic acid, ferulic acid, ellagic acid, quercetin, and other phenolic substances ( Huang et al, 2022 ).…”

Influence of Storage Conditions on Stability of Phenolic Compounds and Antioxidant Activity Values in Nutraceutical Mixtures with Edible Flowers as New Dietary Supplements

“…Similarly, Netzel et al [ 8 ] have confirmed the linear relationship between ACW values and total phenolic content in fruit samples and herbs. Due to the variable composition of the nutraceutical mixtures, it may be assumed that fruits and edible flowers contribute significantly to the antioxidant activity expressed as ACW values followed by flakes with colored coating layers [ 8 , 15 ].…”

“…Non-traditional pigmented flakes contain high amounts of phenolic acids and flavonoids, including gallic, vanillic, sinapic, p- coumaric, cinnamic and ellagic acids, rutin, epigallocatechin, and catechin. Most of them have been evaluated as the main contributors to the antioxidant activity in free, soluble bound, or insoluble bound phenolic fractions [ 15 ]. In addition, there are naturally occurring color substances in pigmented grains belonging to the anthocyanins, such as cyanidin-3-glucoside, delphinidin-3-glucoside, cyanidin-3-rutinoside, and their anthocyanidins.…”

Profiling of bioactive compounds and antioxidant activity of aquatic weedIpomoea aquatica

“…Furthermore, some other important polyphenols were also present in the extracts. These bioactive mixes are acknowledged for their oxide reduction properties (Diep et al, 2020;Khan et al, 2020;Št'astná et al, 2019), which might assume a momentous role in the mopping up of ROS and resultant antioxidant activity. The phenolic hydroxyl groups of polyphenol compounds act as hydrogen donors to directly react with radicals and reduce the activities of…”

“…Furthermore, some other important polyphenols were also present in the extracts. These bioactive mixes are acknowledged for their oxide reduction properties (Diep et al., 2020; Khan et al., 2020; Št'astná et al., 2019), which might assume a momentous role in the mopping up of ROS and resultant antioxidant activity. The phenolic hydroxyl groups of polyphenol compounds act as hydrogen donors to directly react with radicals and reduce the activities of •O 2 −, H 2 O 2 , •OH, ROO•, 1 O 2 and other active radicals; polyphenol compounds lessen the formation of free radicals by inhibiting the enzyme activities required to produce free radicals; polyphenol compounds chelate metal ions that prompt free radical production, thus reducing the generation of free radicals; polyphenol compounds inhibit oxidation reactions by increasing the activity of antioxidant enzymes or the expression of antioxidant proteins; and polyphenol compounds generate synergistic antioxidant effects with other substances (Lv et al., 2021; Santos‐Sánchez et al., 2019).…”