Materials starchy

Butanoic acid, CH3CH2CH2COOH, colourless syrupy liquid with a strong odour of rancid butter b.p. (sTC. Occurs in butter as the glycerol ester. Prepared by oxidation of 1 -butanol or by the fermentation of sugary or starchy materials by B. subtilis etc. Oxidized... 

Starch-containing plants Another potential ethanol feedstock is starch. Starch molecules are made up of long chains of glucose molecules. Hence, starch-containing materials can also be fermented after the starch molecules have been broken down into simple glucose molecules. Examples of starchy materials commonly used around the world for ethanol production include cereal grains, potatoes, sweet potatoes and cassava. Typical cereal grains commonly used for ethanol production in the EET are rye and wheat. 

Many of the molecules that make up living organisms are polymers, including DNA, proteins, the cellulose of plants, and the complex carbohydrates of starchy foods. We leave a discussion of these important biological molecules to Chapter 13. For now, we focus on the human-made polymers, also known as synthetic polymers, that make up the class of materials commonly known as plastics. 

Procedures for isolation and measurement of lipids in foods include exhaustive Soxhlet extraction with hexane or petroleum ether (AOAC, 1995 see Basic Protocol 1), chloro-form/methanol (Hanson and Olley, 1963 Ambrose, 1969), chloroform/methanol/water (Folch et al., 1957 Bligh and Dyer, 1959 see Basic Protocol 2 and Alternate Protocol 2), acid digestion followed by extraction (see Basic Protocol 4), or, for starchy material, extraction with n-propanol-water (e.g., Vasanthan and Hoover, 1992 see Basic Protocol 3). Each method has its own advantages and disadvantages and successful measurement of lipid content is often dictated by the type of sample and extraction medium employed. Commercial extraction and preparation of edible oils are explained in the literature (Williams, 1997). 

About 600 species of Dioscorea (Dioscoreaceae) are known, and a number of these are cultivated for their large starchy tubers, commonly called yams, which are an important food crop in many parts of the world. Important edible species are Dioscorea alata and D. esculenta (S E Asia), D. rotundata and D. cayenensis (W Africa) and D. trifida (America). A number of species accumulate quite high levels of saponins in their tubers, which make them bitter and inedible, but these provide suitable sources of steroidal material for drug manufacture. 

Takeo, K.,Kuge, T. 1969. Complexes of starchy materials with organic compounds. Part III. X-Ray studies on amylose and cyclodextrin complexes. Agric. Biol. Chem. (Tokyo), 33, 1174-1180. 

Since the result of the starch reaction depends on the type of starch, the blue reaction is suitable for the characterization of different varieties of starchy materials,76,77,105,162,256-275 and a special coloristic scale has been developed for industrial purposes.276 A negative correlation was observed257 between the color density of the complex and the stickness of cooked starchy material. 

Isolation of Starch.—Starch is also used as a food in its pure form. To obtain this the plant part, e.g., potatoes, corn, etc., is macerated and then stirred up with a large amount of water. The watery mass is passed through seives to remove the fibrous material while the starch, in suspension, passes through. On allowing the starchy liquid to settle the starch is obtained as a sediment in quite pure condition. As the materials used contain relatively little else than starch and water there is not much foreign substance present. Starch so prepared is the common form in which it is sold under the names of corn starch, and laundry starch, the former used as a food and the latter as a laundry sizing material. 

FIGURE 2.7 SEM micrographs of starch granules in different starchy raw materials potato (a), wheat (b), and maize (c). (From Juszczak, L., unpublished. With permission.)... 

The shape and size of starch granules are specific for different starchy raw materials (Figure 2.7). 

Another potential feedstock for ethanol production is the lignocellulosic biomass . Lignocellulosic biomass is the most plentiful of all naturally occurring organic compounds. It includes such materials as wood, herbaceous crops, agricultural and forestry residues, waste paper and paper products, pulp and paper mill waste, and municipal sohd waste. Unlike starchy materials, lignocellulosic biomass is structurally complex. The conversion of this material into ethanol has been the subject of intense study over the last 20 years. 

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