Valentyuk N.O. Improvement of the technology of postharvest processing and storage of amaranth grain. – On the rights of the article.
Thesis for a Candidate Degree in Engineering (Doctor of Philosophy), specialty 05.18.02 “Technology of cereals, legumes, cereals and compound feeds, oilseeds and bast crops”. – Odessa National Academy of Food Technologies, Odessa, 2019. The thesis is focused on the improvement of the technology of post – harvest processing and storage of amaranth grain, which will guarantee its proper quality and safe long – term storage. The object of research has been the technology of postharvest processing and storage of amaranth grain, the subject of research was the amaranth grain of the Ultra and Kharkovsky varieties of 2006-2014 crops grown in Kherson region. Physical-mechanical properties of amaranth grain are investigated in the work and regularities of their change depending on grain moisture in the range 9.2...19.3 % are established. It has been shown that with increasing grain moisture the geometric dimensions of grain, the mass of 1000 grains increases, the porosity, the rate of natural sloping, and the coefficients of external friction at rest and motion. Nature (volume mass) decreases. On the basis of the study of the particle size distribution of freshly harvested amaranth grain, it has been established that a set of sieves with circular openings of the following sizes (mm) can be used to isolate its main contaminants in grain separators: Б1 – 1,0...1,1; Б2 – 1.0...1.1; В – 0.6...0.8; Г – 0.6...08; and oblong holes with dimensions (mm): Б1 – (0,8...1,0) × 20, Б2 – (0,5...0,7) × 20, Б1 – (0,4...0,6)×20. The results of studies of the aerodynamic properties of amaranth grain have made it possible to establish that the amaranth grain grain velocity is 3.28...3.51 m/s, and the coefficient of sail respectively 0.91...0.79 depending on the initial moisture content of the grain. The thermophysical characteristics of amaranth grain (specific heat, coefficients of thermal conductivity, thermal conductivity and thermal activity) are determined, depending on its humidity and temperature. The empirical equations were obtained, which allow to calculate thermophysical characteristics at grain moisture content of 9.4...19.6 % and temperature 5...25 °C. It is shown that it is possible to achieve the conditioning moisture content of grain within the permissible temperature of its heating without deteriorating the quality of dried amaranth in the following drying modes: for convective drying of amaranth for food purposes in mine grain dryers at a drying agent temperature of 50...60 °C, and for drying at a temperature of the drying agent is not higher than 50 °C; for IR drying at radiator power not exceeding 100 W; at MV drying under pulsed (oscillating) modes with duration of pulses of energy supply of 4 s and duration of pulses of purging with outside air 20...40 s. It is shown that the largest reduction of squalene occurs when using IR drying. However, this method can be used if it is not intended to produce oil, but flour, blown grains, etc. products. Sciencebased technology and optimal modes of different ways of drying amaranth grain allow you to obtain grain moisture and quality conditionally, as well as reduce energy costs for its post-harvest processing. The joint effect of temperature and humidity of amaranth grain on the intensity of its respiration was investigated, an empirical equation describing this dependence was obtained. The study of chemical indicators of quality of amaranth grain showed that when stored under relative humidity those of air φ = 75 % and temperatures of 25 °C the acidic number of fat (from 5.56 to 38.20 mg KOH) and acidity (from 2.45 to 7.15 deg. of acidity) in the alcohol hood change the most. Therefore, reducing the storage temperature of the seed to +4...+6 °C under conditions of relative humidity φ = 55...75 % guarantees the extension of the life. The results of microbiological studies have shown that the conservative effect of low temperatures, which significantly reduces the life of microorganisms occurs at temperatures of +5...15 °C and relative humidity φ = 55 %. It is shown that storage of amaranth grain at a temperature of 15 °C and relative humidity φ = 75 % contributes to the development of microorganisms. However, storage at the same relative humidity, but at a temperature of +5 °C, stops the reproduction of microorganisms. Advanced technological schemes of postharvest amaranth grain processing using convective and combined convective microwave drying methods are proposed. Recommendations for postharvest amaranth processing have been developed and costeffectiveness of implementation of work recommendations have been determined. Keywords: amaranth, postharvest grain treatment, amaranth drying, amaranth cleaning, amaranth storage.
