In this study we investigated the effect of adding soy flour and soy meal flour in different ratios, as well as addition of transglutaminase on sensory properties, colour, texture, aroma, contents of spermine and spermidine, protein content, fat content, antioxidative potential and digestibility of protein and fat in sponge cake. Cakes with an addition of 30 % and 50 % of soy are sensorically and texturally acceptable, since they hardly differ from the control cake. Joint sensory grade of control is still the highest, although some panellists preferred the taste and aroma of soy cakes. We used cakes with 50 % soy flours for the digestion analysis, which we did by the INFOGEST 2.0 protocol. Digestibility of protein in soy cakes is comparable to control cake, the relative content of soluble protein in all samples after digestion was approximately between 70 % and 75 %. The relative percentage of released free fatty acids was much larger in the control cake, which consequently shows worse digestibility of fat in cakes prepared with soy flour. The use of rabbit gastric extract, containing pepsin and gastric lipase, improved the digestibility of fat by 18 % compared to pepsin. We showed that soy is relevant for improvement of nutritional value of cakes. The content of protein, antioxidants, biogenic amines spermine and spermidine was higher and the ratio of omega 3 to omega 6 fatty acids was increased. At the same time, the sensory and textural properties were not significantly worse.
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