| Abstract [eng] |
Bread bakery products are currently produced using rapid technologies, where the long fermentation process with lactic acid bacteria is completely changed by chemical additives. In this technology, grain components, such as proteins, are not degraded during the production process resulting in less digestible food components that can cause various allergic reactions. In this project, the possibilities of using proteolytic enzymes of bacterial origin and ultrasound for efficient reduction of gluten protein in cereal products were investigated. For the treatment of whole grain wheat flour, fermentation with different lactic acid bacteria was used evaluating the changes in the acidity of the medium and lactic acid bacteria proteolytic activity and formation of soluble proteins in the fermentation medium. An ultrasound of 37 kHz frequency (intensity 100%, power 70 W) was used for the activation of lactic acid bacteria enzyme system and raw material treatment. The effect of ultrasound treatment on lactic acid bacteria proteolytic activity and the effect of complex ultrasound treatment and lactic acid bacteria fermentation on wheat gluten fraction protein changes and the influence of applied measures on the parameters of dough texture were evaluated. During the experiment, microorganisms with highest proteolytic activity in whole grain wheat flour medium as well as optimal fermentation conditions were selected. It was found that Lactobacillus brevis LUHS140 had the highest proteolytic activity (0.011 AV/ml) in tested medium after 24 h of fermentation. Also, Lactobacillus brevis LUHS140 proteolytic activity increased two times after 30 min of ultrasound treatment. Evaluating the effect of lactic acid bacteria proteolysis and ultrasound on changes in gluten protein fractions provided the findings showing that by fermenting pure gluten with Lactobacillus brevis LUHS140 it is possible to decrease the amount of gliadins 2,3 times in comparison to an unprocessed gluten. Additional ultrasound treatment reduced the gliadins 6,3 times. Combined application of ultrasound and lactic acid bacteria fermentation allowed to reduce the amount of gliadins 3,8 times. Combined application of ultrasound, lactic acid bacteria fermentation and Saccharomyces cerevisiae yeast reduced the amount of gliadins by further 50 % (till 0,16 mg/g). The qualitative analysis of gliadins confirmed that ultrasound and lactic acid bacteria proteolytic enzymes affected the full hydrolysis of the gliadin fraction of pure gluten. In all cases, glutenins were not affected as much by the applied measures as gliadins. Applied biotechnological measures and application of ultrasound lowered the texture parameters of the dough, which proves a high degree of hydrolysis of prolamins. This technology may be applied to produce fermented products without gluten or with a smaller gluten amount. |
