B4-FV18-B manent magnet Oil drain valves which can be orde Bevel-helical gear boxes B4

Flender/Flender Gear Units/Bevel-helical gear boxes B4

yer because of its low melting temperature. However, it sometimesdoes not produce good seal with starchy or greasy food products. The choice of sealantlayer for these food products is either EVA or Surlyn. 5 BARRIER PROPERTIES OF PACKAGING MATERIALS Many materials can be selected for packaging fruit and vegetable products. When choosing the appropriate packaging material, the following factors should be considered: gas barrierproperties, moisture barrier properties, antifog properties, machinability, mechanicalstrength, sealability, and performance versus cost Among the most important characteristics are their barrier properties to both oxygen and moisture vapor, which vary greatly from material to material. High barrier materials usually are high barriers to both moisture and oxygen, .., glass, tinplate, and aluminumfoil. However, the barrier properties to both oxygen and moisture may be different and mayalso vary as function of the relative humidity and temperature of the storage conditions. Agood example is EVOH, hygroscopic lm that is an excellent oxygen barrier at low relativehumidities. However, at higher relative humidities it absorbs moisture, which has plasti-cizing effect and reduces the barrier characteristics to oxygen. Some lms have mixed barrier properties, .., low oxygen barrier characteristics and high moisture vapor barriers. good example is LDPE; for this reason this lm is selected for packaging fresh meatand produce and for frozen stored products to prevent freezer burn. 6 PACKAGING OF FRUITS AND VEGETABLES The shelf life of packaged fruits and vegetables is controlled by the properties of the product (including water activity, pH, susceptibility to enzymic or microbiological deterio-ration, mechanism of spoilage, and requirement for or sensitivity to oxygen, light, carbondioxide, and moisture) and the properties of the package. Moisture loss or uptake is one of the most important factors that control the shelf 5 Smith et al. life of fruits an