engleski

Enrichment of the Traditional Bakery Products with the Soybean Proteins

In Mediterranean dietary pyramid bread is one of the basic foodstuffs. In Mediterranean countries besides the wheat breads consumers prefer mixed corn bread due to its sweet taste. This is opposite to the Western Europe countries where sour rye breads are preferred. Mixed corn bread contains at least 20 % (w/w) of the corn flour. It is well known that cereal proteins are deficient in lysine, threonine and tryptophan which are the essential amino acids. On the other hand, proteins of food legumes and soybeans are relatively rich source of those amino acids. Soy protein usage for enrichment of bakery products considerably contributes to enhance nutritive properties as well as their freshness and shelf life. For that reason, mixed corn bread was prepared with addition of texturated defatted soy proteins (TDSP) and extruded mixture of corn flour and defatted soy flour (EMCSF). The corn flour (ECF) and mixtures of different mass ratios of corn and defatted soy flour were extruded: 87.5:12.5 (M1) ; 75:25 (M2) ; and 62.5:37.5 (M3), respectively. Influence of extrusion conditions such as extrusion temperature, screw speed and moisture content on the amino acid availability and protein digestibility, were investigated. Mixed corn breads were made from 60 % (w/w) of wheat flour and 40 % (w/w) of EMCSF or 35 % of ECF + 5 % TDSP ; 30 % of ECF + 10 % TDSP ; and 25 % of ECF + 15 % TDSP. In all raw materials and final products crude protein content, amino acid composition and proteins digestibility in vitro were determined. Availability of the essential amino acids in extruded flours is increased with regards to raw corn and soybean flours. Mixed corn breads with added soybean products had higher protein content and higher amino acid score for all three limiting amino acids proportionally to soy protein content. Amino acid score was the highest in mixed bread with addition of 40 % of M3 but the sensory characteristics were lower evaluated (mark 3.7). Lysine score in that bread was raised by 45 % in comparison to non-enriched bread, and other limiting amino acids scores were near 1. Protein digestibility and amino acid score were much lower (for 30 %) in the bread crust than in the crumb.

Backery products; soj protein

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