Nutritional value of protein in wheat-rye bread manufactured with addition of flour from low-Alkaloid cultivars of lupin

Abstract

Introduction. The aim of this study was to assess the nutritional value of protein in wheat-rye bread manufactured with an addition of flour from low-Alkaloid cultivars of lupin. Material and methods. Flours from yellow lupin cultivars: Juno, Polo, Legat and Markiz, were used in wheat-rye bread baking. The following were determined in breads: protein content, in vitro protein digestibility, amino acid composition, effective protein content (EP), chemical score (CS), essential amino acid index (EAAI), true digestibility of protein (TD), protein digestibility corrected amino acid score (PDCAAS) and protein efficiency ratio (PER). Results and discussion. The addition of lupin flour resulted in an increase in the total protein and digestible protein in breads. The greatest increase in the EP, CS, PDCAAS and EAAI was observed when the bread was enriched with flour from Polo cultivar. No significant changes were noted in PER. Protein in the products with lupin flour contained more leucine, lysine, asparagine and arginine, than the cotrol sample. A tendency has been recently observed to enrich cereal products, mainly those made from wheat and wheat-rye mixes, with flours obtained from other plants, such as lupin, green peas, beans, hemp and buckwheat. These flours are highly valued because of their functional properties, which include solubility, emulsifying capabilities, foaming and gelling properties, and water retaining capability. Lupin flour and protein isolates from lupin seeds does not affect the taste of a final product. An addition of lupin flour to wheat bread improves considerably the quality and amount of protein and dietary fibre in a final product. The high values of indices PDCAAS and PER make it possible to compare lupin proteins and proteins of leguminous plants to animal proteins. Conclusions. Protein of low-Alkaloid cultivars of lupin can be a valuable component which increases the nutritional value of bread protein and therefore it should be recommended for use in baking.