Vol 109, No 6 (2020)

The generation of medically pure oxygen is an urgent problem of today. The observation of the operation of air separation plants over a long period of time made it possible to define that in Russia in hot regions in summer the produced capacity of air separation plants (ASP) decreased as well as the quality of the product. To improve the high pressure ASP operation the authors offer to implement an energy saving system on the basis of the lithium bromide refrigerating machine providing atmospheric air cooling before supplying into a compressor. Whereupon, a special role is given to the definition of the concentration of oxygen generated.

The article gives the results of a study of the influence of an oxygen reduced concentration and a carbon dioxide increased concentration at cold storage of apples of autumn variety on the activity of terminal oxydases, involved in the regulation of physiological and biochemical processes at the final stages of oxidation of respiration substrates. The aim of the research is to study the change of the activity of terminal oxidases depending on the cold storage duration in the gaseous atmosphere with reduced oxygen concentration and increased carbon dioxide concentration formed by a biological method using gas selective track membranes. The test subjects were the apples of autumn varieties Grushovka Yudicheva, Kordonovka and Pepin Shafranny, grown according to the generally accepted technology in the garden of collection trees of the Pavlovskaya experimental station of the N.I. Vavilov VNIIR. To form a gaseous atmosphere during the storage of autumn variety apples a new composite membrane was used, it consisted of a substrate based on the polyethylene terephthalate (PET) track membranes (TM) and a selective layer based on the organosilicon block copolymer (pore diameter 0,2 µm, selectivity 5,0). This membrane was developed in laboratories of the A.F. Ioffe PhysicalTechnical Institute and S.V. Lebedev NIISK. It was shown that during storage the change of the terminal oxidase activity depended on the apple variety, storage duration, gas composition and enzyme type. The kinetic dependences of changes in the activity of phenol oxidase, peroxidase, and catalyse enzymes on the storage duration of autumn apple varieties Grushovka Yudicheva, Kordonovka and Pepin Shafranny in the normal atmosphere (NA) and controlled atmosphere (CA) were revealed. The regression equations characterizing these dependences were obtained. The velocity constants of inactivation reactions of the enzymes studied during storage of autumn varieties in NA and CA were determined. It was established that the activity of the enzymes of phenol oxidase, peroxidase, and catalyse decreased when storing apples in CA with reduced oxygen concentration (up to 5,2±0,1%) and with increased carbon dioxide concentration (up to 3,6±0,1%) decreased. The velocity constants of enzyme inactivation reactions decreased 1,15-1,77 times depending on the variety and enzyme type. It was shown that when the apples adapted to the positive low temperature and the modified gas composition, then the terminal oxidases performed the regulatory function.