Oilseed By-Products Valorization Using Lactic Acid Fermentation: Nutritional and Technological Aspects of Applications in Wheat Bread

This study aimed to determine the effect of lactic acid fermentation with Lactiplantibacillus plantarum on the bioactive compound composition and fatty acid profile of black cumin, camelina, milk thistle, and evening primrose cakes, as well as to evaluate their application as ingredients in wheat bread production (9% of wheat flour substitution). Fermentation increased the content of flavonoids and phenolic acids in camelina cake by approximately 30%, while causing a 30% decrease in carotenoid content. In black cumin cake, an eightfold increase in 4-hydroxybenzoic acid content and a 10% reduction in thymoquinone were observed. For milk thistle, silymarin content decreased by approximately 10%. Fermentation increased the proportion of saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs), reducing polyunsaturated fatty acids (PUFAs) in all analyzed cakes. Breads containing 9% fermented cakes exhibited lower specific volume and greater hardness (22–80%), gumminess (17–64%), and chewiness (8–48%), compared to the breads with unfermented cakes. The contents of bioactive compounds in breads depended on the type of cake added. The bread with fermented camelina cake showed a 15% increase in flavonoid content and higher levels of selected phenolic acids compared to the bread with unfermented camelina. The breads containing camelina cake, both fermented and unfermented, also had the most favorable physical quality (texture and volume). The amount of ferulic acid in all samples of bread with the addition of fermented cakes was lower in comparison to the bread samples with unfermented cakes.