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.

In this study, the changes in nutritional composition, phenolic compounds and antioxidant activity in free and bound fractions of shortcrust cookies were investigated. By incorporating ingredients such as kamut, matcha tea, dried mango and jasmine flowers, the contents of crude and neutral-detergent fibre reached up to 2.0 and 5.0%, respectively. Similar increments were observed in phenolic compound contents and 2,2-diphenyl-1-picrylhydrazyl scavenging activity values. Concerning cookies supplemented with matcha tea, the total phenolic compound content raised from 1.0 to 4.8 mg gallic acid equivalent/g and the antioxidant activity value increased from 0.5 to 5.7 mg trolox equivalent/g on a dry weight basis. For determining the antioxidant activity values in water-soluble and insoluble phenolic fractions of the cookies, a photochemiluminiscence assay was separately applied, and they were found up to 0.8 mg ascorbic acid equivalent/g and 3.2 mg trolox equivalent/g, respectively. The main phenolic compounds in all supplemented cookies were neochlorogenic, gallic and vanillic acids.