Food processing oxidation

Rich sources of vitamin A include dairy products such as milk cheese, butter, and ice cream. Eggs as well as internal organs such as the Hver, kidney, and heart also represent good sources. In addition, fish such as herring, sardines, and tuna, and in particular the Hver oil from certain marine organisms, are excellent sources. Because the vitamin A in these food products is derived from dietary carotenoids, vitamin A content can vary considerably. Variation of vitamin A content in food can also result from food processing and in particular, oxidation processes (8). 

The chief source of such energy is the combustion of carbon compounds to C02. You know that man exhales more carbon dioxide than he inhales in the air he breathes. This extra carbon dioxide is one of the products of the oxidation processes by which food is oxidized and energy is liberated. 

Antioxidants are not important only to the health conscious food manufacturers also rely on these chemicals to maintain the shelf life of their products. Synthetic antioxidants such as butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate and tert-butyl hydroquinone were widely used in food processing to control oxidation and maintain food quality. However, as these synthetic antioxidants are suspected to be carcinogenic they now have restricted use in food (Madahavi and Salunkhe, 1995). Therefore, natural antioxidant sources, especially of plant origin, are of great interest to the food industry. 

Table 16.2 Examples of recent developments in use of plant materials or extract of plant material for protection of processed food against oxidation... 

Evans, P.H., Campbell, A.K., Yano, E. and Morgan, L.G. (1989a). Environmental cancer, phagocytic oxidant stress and nutritional interactions. In Nutritional Impact of Food Processing (eds. J.C. Somogyi and H.R. Muller) pp. 313-326. Karger, Basel. 

Flavor is one of the major characteristics that restricts the use of legume flours and proteins in foods. Processing of soybeans, peas and other legumes often results in a wide variety of volatile compounds that contribute flavor notes, such as grassy, beany and rancid flavors. Many of the objectionable flavors come from oxidative deterioration of the unsaturated lipids. The lipoxygenase-catalyzed conversion of unsaturated fatty acids to hydroperoxides, followed by their degradation to volatile and non-volatile compounds, has been identified as one of the important sources of flavor and aroma components of fruits and vegetables. An enzyme-active system, such as raw pea flour, may have most of the necessary enzymes to produce short chain carbonyl compounds. 

Energy is extracted from food via oxidation, resulting in the end products carbon dioxide and ivater. This process occurs in the four stages shown in Figure I-ll-l. 

The final stage in the extraction of energy from food is oxidative phosphorylation, in which the energy of NADH and FADHj is released via the electron transport chain (ETC) and used by an ATP synthase to produce ATP. This process requires O. ... 

In the food processing industry flour doughs are baked. This involves many processes such as (I) rising of dough by evolution of CO2 by yeast-catalyzed oxidation of sugar to vapor in pockets or by decomposition of baking powder,... 

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