Other plant by-products

When cottonseed flours and some other plant-protein products are used in food applications, there is a serious discoloration problem. Plant phenolic constituents are the major contributors to this problem. When cottonseed flours are used in food products, a yellow coloration is caused by cottonseed flavonoids. 

Color in food products ranks second in importance to taste in relation to consumer acceptability of a product. Discoloration problems caused by plant-protein products must be solved if these products are to be accepted. Isolation and identification of the pigments producing color is an important step in solving this problem and the methods developed in the studies presented in this chapter with cottonseed flours are applicable to color problems caused by other plant-protein products. 

Air quality is important from both a health and a safety perspective. In the USA, the National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration set limits of exposure to over 2000 different chemicals or classes of respiratory irritants [11, 12], Many of the compounds that are monitored indoors are of similar interest to outdoor assessment, such as in the atmosphere and stratosphere. VOCs emitted from industrial operations are continuously monitored as required by US and local Environmental Protection Agencies. Power plants and waste incinerators are required to follow emission guidelines for harmful combustion gases, including CO and NO, as well as other combustion by-products, including polycyclic aromatic hydrocarbons, phenols, and hy-... 

In addition to promoting the production of rubber (latex) by ethephon, which is already being practised (14), increasing the iso-prene content of other plants by different active substances should also be mentioned (15), as well as the trials for enhancing the quality of vegetable oils by treatment with pyridazinones (16). 

Xylose is not a by-product of furfural but its precursor. On account of this, its production is governed by the very kinetics of furfural formation, but with the aim of avoiding the latter as best as possible. However, the technically most important difference between xylose production and furfural production is the fact that furfural, because of its low-boiling azeotrope with water, is readily recovered as a vapor, whereas xylose, being nonvolatile, ends up dissolved in the liquid reaction medium, together with many other unwanted by-products, from where a recovery in a sufficiently pure form is not as easy as in the case of separating a product from a vapor mixture. Consequently, xylose plants are far more complicated, and therefore more costly, than furfural plants. 

Oxygen molecules are the other major by-product of the light-independent stage of photosynthesis. Plants provide the oxygen needed for animal respiration on Earth (see chapter 5). 

All enzymes are proteins. They are isolated from microbial fermentations and animal and plant by-products. The one feature of enzymes that places them above all other forms of catalysts is their remarkable specificity to a desired product. Enzymes are essentially large molecules whose molecular weights range from 10,000 to several million and whose cross-sectional dimensions extend up to about 10 nm. To develop catalytic action, however, many enzymes require the cooperation of low molecular weight nonprotein substances known as coenzymes or cofactors. The protein moiety in such cases is specifically referred to as apoenzyme. There are essentially six classes of common enzymes, as listed in the first part of Table 20.1. 

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