Efeitos da umidade e do sistema de armazenamento na qualidade industrial de grãos de aveia

Abstract

This work aimed at testing the efficiency of the stationary drying with slightly heated air and the influence of the moisture on the hermetic and conventional systems during a storage period of twelve months with the objective of indicating quality maintenance parameters for white oat kernels (Avena sativa L). Grains of the cultivar UPF 18 produced at the Agricultural Center of Palma UFPel, Capão do Leão, RS, agricultural cropping season of 2001 were used and evaluated according to the moisture, centesimal composition, fat acidity, fatty acids, viscosity, color, falling number, residual activity of peroxidase and lipase enzymes, germination, vigor, fungi contamination, mycotoxin occurrence, and the CO2 concentration in the intergranular atmosphere of the hermetic storage. The work was divided into two studies. In Study 1 it was evaluated the conservability parameters in the storage hermetic system for twelve months of grains with a moisture percentage of 9, 12, 15, 18 21% respectively. In Study 2 the conventional and hermetic storage systems were compared in oat grains with moisture of 8, 11 e 14%. It was concluded that: a) the hermetic storage of oat grains with moisture between 9 and 21% does not favor the production of aflatoxins (B1, B2, G1e G2), ocratoxin A and not even zearalenona, at least during the period of twelve months, independently of the moisture degree; b) the amount of CO2 in the intergranular atmosphere in the hermetic storage has linear behavior and is directly proportional to the moisture and storage time. c) the field fungi decrease the incidence during the hermetic storage time, independently of the moisture of the grains; d) the moisture degree of the grains has influence on the fungi incidence during the hermetic storage, with predominance of the Aspergillus e Penicillium type, at a moisture level of 18%, and of the Fusarium at 21%; e) the increase of the storage time and moisture of the grains in values which are higher than 12% intensifies the reduction of nonsaturated fatty acids, with action predominance on the linoleic and linolenic; f) the stationary drying, with slightly heated air is an efficient method in the oat grain conservation; g) the hermetic and conventional systems are efficient for the conservation of oat grains with moisture of up to 14% ; h) in the conventional storage system with periods of up to 12 months there is a conservative equivalence in grains stored with 8 and 11% of moisture; i) in oat grains conventional storage system for a period superior to six months the moisture must be below 14%; j) in hermetic system there is a conservative equivalence of oat grains stored for up to 12 months with moisture of 8, 11 e 14%