PLANT PRODUCTS
introduction:
Plants that are food come in a wide range of internal pH). This is because plant cells store acids in their central vacuole. Most plants have tough outer layer, its cuticle that can be dry and waxy as well as contain inhibitory secondary metabolites. Some plant products are near dry, others are watery. Great diversity.
Cereals (wheat, rice, corn, barley, sorghum) come from the grass family, Gramineae, and are the principle source of carbohydrate in human diet (Table 5.9 lists the more common cereal plants). The main microbes on cereals are xerophilic molds; e. Field fungi are the major microbes surviving on cereals, but upon storage are joined with molds having even lowered minimal aw for growth. Thus, the most important aspect in storage is controlling relative humidity. Cereals absorb water from the air (weight gain) thus allowing these molds to begin growing and spoiling the cereal grains. Molds cause discoloration, off odors, and some can produce toxins before the complete decay of the grains is apparent.
For high moisture grains, such as barley, these can be fermented by lactic acid bacteria to form silage, which is not for human consumption, but is a nutritious food for livestock. Lactic acid prevents further spoilage. Other methods add fatty acids or prop ionic acid to the grains to maintain them
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