CHANGES IN QUALITY OF AMARANTH GRAIN IN THE COURSE OF POSTHARVEST HANDLING AND STORAGE

Abstract

One of the solutions to the problem of people’s health deterioration is the wide use of plant products. The most valuable of them are vegetable oils, including amaranth oil. The latter contains a complex of vitamins, macroelements and trace elements, unsaturated fatty acids and essential amino acids, and the unique natural bioactive substance squalene, which performs a number of key functions in the human body. However, postharvest treatment of amaranth grain, in particular, drying and subsequent storage under different conditions, can significantly impair its valuable natural properties. The research presents the findings on how the chemical composition and microbiological characteristics of amaranth grain change in the course of its drying and storage under different conditions, which can ensure its high quality during storage. It has been studied how drying amaranth to the moisture content 9% at 50°С and 60°С effects on the total amount of saponified substances and on the content of squalene, linolenic, linoleic, oleic, palmitic, and stearic acids (determined by gas–liquid chromatography). It has been found that after amaranth grain is dried, it loses 10% of saponified substances and 14% of squalene, as compared with freshly harvested grain, while the content of free fatty acids in the unsaponified fraction does not change. It has been determined how storing amaranth throughout a year at +5°С, +15°С, and +25°С, at the relative humidity 55% and 75%, changes such basic grain quality parameters as the content of protein, starch, fibre, fat, and ash, the acid value, and the acidity of fat. The biggest were the changes after a year’s storage at 25°С and the relative atmospheric humidity 75%: protein decreased by 13.5%, starch by 8.7%, fat by 29.0%. There was almost no change in the contents of fibre and ash. Besides, these storage conditions resulted in a significant deterioration of the fat quality: its acid value increased by 6.9 times, and the alcohol extract acidity by 2.9 times. When amaranth was stored at +5°С and the relative humidity was 55%, the decrease in the content of the main components was appreciably smaller: 8.1% for protein, 2.9% for starch, and 4.2% for fat. Under the same conditions, the activity of microorganisms is significantly lower. All this allows recommending these storage conditions for industrial use.