The effect of phenolic compounds contained in flour from green buckwheat, flaxseed, grape and dogwood seeds on the fermentation activity of yeast S. cerevisiae

Abstract

Background: Bakery products are one of the most widely consumed in the world, but they have very low nutritional value and a short shelf life. Unconventional flour can be used to address these issues. They contain vitamins, minerals, and polyphenols that can significantly increase the nutritional value of the final product. It is known that phenolic compounds have a beneficial effect on the human body, preventing various diseases, inactivating free radicals, and also suppressing the growth of pathogenic microorganisms that develop in bakery products. Despite these advantages, unconventional types of flour have a specific biochemical composition that can negatively affect the course of the technological process. One of the most important stages in the production of bakery products is fermentation. Earlier studies have shown that phenolic compounds can be adsorbed by yeast, but high concentrations significantly reduce the viability of yeast cells. Objective: To study the influence of phenolic and flavonoid compounds contained in flour from green buckwheat, flax, grape, and dogwood seeds on the fermentative activity of S. cerevisiae yeast. To achieve this goal, it was necessary to determine the total amount of phenolic and flavonoid substances contained in flour from grape and dogwood seeds, green buckwheat, and flax flour, and to study the effect of flour and individual phenolic compounds on the fermentative activity of yeast. The most common polyphenolic compounds in all three types of flour were selected for the study – rutin, gallic acid, and tannin. Methods: The fermentation activity of yeast was assessed by measuring carbon dioxide release during fermentation, with samples prepared using varying concentrations of flour from grape seeds, green buckwheat, and dogwood seeds. Ethanol extraction from raw materials was conducted using 60% ethyl alcohol, followed by spectrophotometric determination of phenolic composition and flavonoid content. Rutin, tannin, and gallic acid were defined using specific titration and spectrophotometric methods. Results: It was found that flour from grape seeds contains the highest amount of phenolic and flavonoid compounds compared to other types of flour, namely: 1352 milligrams of gallic acid/100 grams and 227 milligrams of rutin/100 grams respectively. The lowest amount was found in flour from green buckwheat – 350 milligrams of gallic acid/100 grams and 109 milligrams of rutin/100 grams respectively. The addition of the tested types of flour positively affects the fermentative activity of bread yeast, increasing the release of carbon dioxide by 1.5-2 times compared to the control sample. The highest amount of CO2 was released when using flour from grape seeds. Studies of the phenolic and flavonoid composition showed that grape seeds contain the highest amount of gallic acid and tannin compared to other types of flour. Individual phenolic compounds have a positive effect on the process of carbon dioxide release. The highest amount of CO2 was released when adding 120 mg of rutin per 1 gram of yeast, which is 2 times higher than the values relative to the control sample. It was noted that the introduction of this amount of rutin shortened the lag phase and increased the logarithmic phase. The fermentation process was most intense in the first 1.5-2 hours. Conclusion: A promising direction is the use of flour from green buckwheat, grape, flax seeds, and dogwood seeds for baking. Since the introduction of phenolic substances does not have a negative effect on the fermentative activity of yeast, these types of flour can be a source of phenolic compounds that can significantly extend the shelf life of products. In addition, additional consumption of phenolic compounds in the human diet has a positive effect on health. Keywords: dogwood seed flour, grape seed flour, green buckwheat flour, flaxseed flour, yeast fermentation activity, phenolic compounds