Effect of cooking and germination on antioxidant activity, total polyphenols and flavonoids, fiber content, and digestibility of lentils (Lens culinaris L.)

Abstract

The aim of this work was to evaluate the effect of cooking and germination on antioxidant activity, total polyphenols and flavonoids, fiber content, and digestibility of lentils (Lens culinaris L.). Seven commercialized samples of lentils (brown, red, dark green, French green, Beluga, dehulled and split red, and dehulled yellow) obtained from the Czech market were analyzed. Lentils were assessed for basic chemical analyses (dry matter and ash content), total phenolic and flavonoid contents (Folin-Ciocalteu and AlCl3·6H2O spectrophotometric methods, respectively), antioxidant analysis (DPPH assay), crude and neutral-detergent fiber contents and in vitro digestibility. Germination caused an increase in total phenolic and flavonoid contents, antioxidant activity, and digestibility and, contrariwise, a decrease in both crude and neutral-detergent fiber contents. Cooking resulted in the rising of digestibility and the reduction of total phenolic and flavonoid contents, antioxidant activity, and both crude and neutral-detergent fiber contents. Practical applications Lentils, among other legumes, exert valuable nutritional composition (including high amounts of protein, fiber, and bioactive compounds with antioxidant activity, such as polyphenols). However, lower digestibility together with some antinutritional factors results in very low consumption of lentils in western diet. Lentils need to be processed prior to consumption. The most widely used processing methods represent thermal processing (cooking) and germination. These processing techniques can influence nutritional quality of lentils since antinutritional factors are reduced. It is crucial to monitor the changes occurring during the culinary processes and to ensure that these processes implicate positive affection of nutritive value of lentils. According to our results, both processing techniques resulted in enhanced digestibility of lentils. Furthermore, germination proved to be more efficient in the antioxidant activity improvement caused mainly by the increased amounts of polyphenols and flavonoids.