Lentils (Lens culinaris Medik) as a Source of Phenolic Compounds - their Content, Changes during Processing, Antioxidant and Biological Activities

While often recognized as a good plant protein source and a rich source of essential nutrients including folate, iron, manganese and phosphorus, lentils (Lens culinaris L.) also contain healthful bioactive compounds. They possess a number of phenolic compounds including phenolic acids, flavonoids such as flavan- 3-ols, flavonols and anthocyanins, proanthocyanidins, as well as saponins and phytic acid. This review provides a summary of the types and levels of phenolic compounds found in the cotyledon of lentils as well as their seed coats. The values define broad ranges due to varied cultivars, horticultural practices, climatic conditions during lentil development, and the different phenolic extraction approaches employed. The prepared lentil extracts were found to possess marked antioxidant activity, as assessed by in vitro assays, with the results clearly indicating that the endogenous phenolic compounds dictated this activity. Processing of raw lentils in the forms of cooking, germination and fermentation was determined to affect the phenolics’ contents: phenolic content of some lentils decreased while those of others increased, most likely due to the release of bound phenolics from the plant wall matrix. Finally, a summary of some of the positive biological activities observed for lentil extracts from cell culture and animal studies is given.