Nutritional characterization of wild legumes (Lathyrus and Vicia genera)

Abstract

In several regions of the world, legumes play an important role in human and animal nutrition as they are a cheap source of protein and other nutrients. In recent years have been shown that the consumption of proteins, certain lipids, polyphenols, or bioactive peptides contained in legumes have a beneficial effect on health. In addition, since the ?green revolution,? a large amount of the world?s phytodiversity has been lost because local crops have been substituted by other genetically uniform crops, which have higher yields. However, the diversification of cultivars is necessary to adapt cultivars to soil and water conditions, or to limit phytosanitary risks. Hence, knowledge of local plants could provide useful data for the possible development of future crops. Vicia and Lathyrus are major genera of the tribe Fabeae and have wild species in Southern Spain. A total of 46 different wild species have been studied. To our knowledge, this is the first time that a deep nutritional characterization of wild populations of Lathyrus and Vicia species has been made. In this work the fatty acid composition of the seed oil, the polyphenol concentration and the antioxidant activity of the polyphenols extracted from the seeds, the amino acid composition and nutritional quality of seed proteins have been studied in 15 Lathyrus species and in 28 Vicia species (31 taxa). The main seed oil fatty acids ranged from C14:0 to C20:0. All studied species showed higher amounts of total unsaturated fatty acids than saturated ones. Among unsaturated fatty acids, the most abundant were linoleic, oleic and linolenic acids. Among studied species, the ɷ6/ɷ3 ratio was variable, ranging from 1.7 in V. articulata to 17.3 in V. faba, there being nine species in which the ɷ6/ɷ3 ratio was below 5. Polyphenolic contents ranged from 1.9 mg/g meal in V. narbonensis to 29.2 mg/g meal in L. sphaericus. The highest specific polyphenols antioxidant activity (referred to as catechin equivalents in the extracts) was observed in the extracts from Lathyrus annuus, Vicia parviflora and Vicia tenuifolia. On the contrary, the highest total antioxidant activity (referred as to extract volume) was observed in L. aphaca y V. sativa. Results show that studied Lathyrus and Vicia species are rich in phenolic compounds with higher antioxidant activity than phenolics of widely consumed legumes such as soy, chickpea or lupin. Protein contents in studied species ranged from 17.7% in Lathyrus sativus to 32% in V. pyrenaica. Among essential amino acids the most abundant were Leu, Lys, Phe, Thr and Val. Also, all species contained Lys above FAO recommendations. On the contrary, all species were limiting in Trp ranging from 0.5% to 1.0% content and were also limiting in sulphur containing amino acids, Met and Cys. In vitro protein digestibility (IVPD) in studied legumes ranged from 76.0% in L. pratensis to 86.5% in L. annuus. Nutritional parameters, such as protein efficiency ratio, corresponded to high quality proteins. Protein digestibility corrected amino acid score was similar to the observed in other commercial legumes such as lentil or peanut. In conclusion, results confirm the interest of studying wild populations of Lathyrus and Vicia species as source of seeds with good nutritional characteristics and contribute to revalorize the cultivation of these legumes.