第六章各类农产品贮藏技术课件.pptx

第六章 各类农产品贮藏技术;Section 1 Grain Storage;;1、Grain harvesting, threshing and cleaning;Physiological maturity;;Harvesting methods Manual harvesting Mechanized harvesting DIRECT METHODS Defoliation and Desiccation Leaving it in the field longer predisposes it to weathering. Sometimes, inclement weather threatens the quality of the harvest, thereby compelling the producer to make adjustments in the harvesting schedule. Such adjustments include “inducing” early harvest maturity by applying a defoliant or desiccant. ;;INDIRECT METHODS Generally, crops are harvested when the conditions of the economic product are such that the product can be stored for a reasonable period of time without deterioration. However, if the product has a facility for drying, the crop may be harvested sooner than normal harvest maturity then dried to storable moisture content at a later date.;(ii) Threshing methods;Combined harvesting and threshing methods ;(iii)Cleaning;2、Drying methods ;Natural methods of drying make use of exposure of the wet grain to the sun and wind. Artificial dryers employ the application of heat from combustion of fossil fuels and biomass resources, directly or indirectly, and in both natural and forced convection systems. Mechanical dryers, long used in developed countries, are finding increased application as farming and grain handling systems develop.;Natural and solar drying ;;Mechanical dryers ;Re-circulating Batch Dryers;;;3、The biodeterioration of grain and the risk of mycotoxins;;;Fungi may infect grain in the field, the major species being Alternaria链格孢属 , Cladosporium枝孢属 , Helminthosporium 长蠕孢属 , and Fusarium镰孢属 . Their role in quality deterioration in storage is minimal. Storage fungi of importance are Aspergillus曲霉, Penicillium青霉, and to a lesser extent Sporendonema丝内霉.;moulds;moulds;moulds;moulds;moulds;moulds;moulds;In certain grains, such as wheat that is cultivated principally for flour, the characteristic elastic properties caused by the protein glu