New Nitrogen-Containing Raw Materials in Distillate Technology

Abstract

Grain bran is used mostly in animal farming and food industry. However, grain bran can also serve as an alternative source of nitrogenous substances in distillate technology. The present research objective was to study the complex of water-soluble nitrogenous compounds in grain bran and to identify the effect of the bran type and its granulometric characteristics on their composition and concentration. The research featured 30 industrial grain samples of wheat, rye, and triticale, as well as the corresponding bran samples. The total protein was determined by the Kjeldahl method, the size modulus – by sieving. In the bran aqueous phase, the protein content was measured using the Lowry method, the amine nitrogen content – by the copper method, and the free amino acid content – by the high-performance liquid chromatography. In bran, the content of total protein increased by 16–28%, the proportion of water-soluble forms of nitrogenous compounds increased by 6–29%, and the free amino acids increased by 1.4–2.3 times, if compared with the grain samples. The proportion of soluble proteins in the rye bran was 15–30% higher than in other types. The types of bran had a different content of individual amino acids. A high correlation was observed between the modulus of the bran size, the mass concentration of soluble proteins, and the free amino acids. The proportion of soluble proteins reached 44.1% as the size modulus decreased. The samples of rye bran demonstrated the maximal growth of this indicator. Bran, regardless of the type of raw material and particle size distribution, had a higher concentration of free amino acids in comparison with the original grain. The experiment revealed the following linear dependence: the proportion of free amino acids in bran increased by 46–54% as the size modulus decreased by 0.72–0.85. The article introduces linear dependence equations for each type of bran, as well as the percentage of free amino acids for the change in the size modulus per unit. Aqueous extracts of small-size rye grain bran proved to have good prospects for distillate technology. According to the evaluation of the nitrogen-containing complex of various grain bran types, small-size rye bran had more advantages in terms of soluble protein forms and free amino acids. Further research will feature the fermentation activity of yeast in distillate production to develop specific sensory properties.

Keywords

• bran
• nitrogen-containing complex
• particle size distribution
• free amino acids
• distillation