Evaluation of functional food ingredients produced by sprouting and fermentation of different grains in terms of bioactive and neuroactive compounds

Sprouting takes place by keeping the grains at a certain temperature and relative humidity for a certain period after taking a certain amount of water into their structures. It is known that sugar and amino acid concentrations increase with the biochemical reactions occurring in the structure of grains during sprouting. Fermentation is also a metabolic biochemical process in which desired changes occur in the food environment via yeast and/or bacterial activity in order to increase flavor, protect food, and provide health benefits. The main purpose of this thesis is to understand the sprouting and various fermentation processes of grains and the change and/or formation of their bioactive and neuroactive components since the results of the combined sprouting and fermentation process are lacking in the literature. In this study, six types of grains, namely wheat, barley, rye, oat, einkorn and buckwheat, were used as materials. Commercial yeast and sourdough fermentation were applied to selected grains at different temperatures (10-40 °C) and times (1-36 hours) after each sprouting for an appropriate time (36-72 hours). Thus, 6 sets of samples were created: native, sprouted, commercial yeast fermented, sourdough fermented, sprouted and commercial yeast fermented, and sprouted and sourdough fermented. Total phenolic compounds analysis, free phenolic compounds analysis, antioxidant capacity analysis, amino acid analysis, amino acid derivatives analysis and melatonin analysis were applied to these sample groups. As a result of the analysis, no significant changes were observed in the phenolic acid concentration, antioxidant capacity, and melatonin concentration in general. It has been observed that the combination of sprouting and sourdough fermentation creates a synergistic effect for the generation of tyrosine derivatives. More tyramine, L-DOPA, and dopamine formation were observed during sourdough fermentation than yeast fermentation. It has made a significant difference especially in the formation of L-Dopa and dopamine. As a result of the combined sprouting and fermentation processes at 10 °C-36 hours, the L-DOPA concentration increased the most in einkorn, increasing 955 times and as a result of the combined sprouting and fermentation processes at 30 °C-36 hours, the dopamine concentration increased the most in einkorn, increasing 273 times. Tryptophan derivatives showed significant increases only in samples fermented with commercial yeast. The most increase is in kynurenic acid with the commercial yeast fermentation of wheat at 30 °C-3 hours with 28 times.