Food processing quality loss

Carbohydrates and proteins are typical hydrophilic components of concentrated food systems. These components tend to form amorphous, noncrystalline structures at low water contents (White et al. 1966 Slade et al. 1991 Roos 1995). Well-known food processes resulting in glass formation by amorphous or partially amorphous food components include baking, extrusion, dehydration and freezing (Roos 1995). In these processes, removal of water as part of the manufacturing process results in the formation of a noncrystalline, amorphous state, which is extremely sensitive to water and may show various time-dependent changes causing loss of quality and reduced shelf life. 

Generally food processing causes irreversible denaturation followed by reactions of the thermally denatured proteins with other components that may lead to loss in food quality. However, in foods denaturation may have beneficial or detrimental effects. The main effects comprise changes in pi, hydration, solubility, viscosity of solutions, biological activity, and reactivity of a.a. residues. 

It is frequently u.sed as an additive to foods where it enhances the nutritious qualities. It may be added to restore loss of vitamin due to the food processing or to increase the natural amount of the vitamin present. In either ca.se the term nutrification has been used to describe its addition. Thus, L-ascorbic acid is added to fruit juice to fortify that which is naturally pre.sent or it may be added to artificial fruit drinks to improve taste and the nutritiousness of the drink. 

Lipid oxidation is an important topic in food science and technology since the reaction of polyunsaturated fatty acids with oxygen leads to rancidity and quality loss. The same process is important in human health, since the polyunsaturated fatty acids from lipids present in blood plasma (low density lipoproteins, LDL) are oxidised by oxygen in a free radical mediated reaction, promoting the development of atherosclerosis. LDL enters the arterial wall from the plasma and is oxidised locally within the wall by oxidising agents derived from the cells present in atherosclerotic... 

Control points (CPs) are the points in the process where loss of control is not likely to result in unacceptable health or safety risk, but correction is required. The difference between CCPs and CPs requires careful review by quality assurance (QA) and food safety experts experienced in working in HACCP programs (MFSC/NFPA, 1992). 

The PAC approach is quite different from the traditional way of food process control, where samples are taken at different point of the process and then transported to the central laboratory, stored, and analyzed with sophisticated instrumentation. In comparison, PAC analyzers are located in or right next to process and are considered physically and operationally part of the process. Besides the location of the instrumentation, time frame is another characteristic that distinguish PAC from the traditional analytical philosophy. In fact, a centralized laboratory usually can take hours or day before returning the results while PAC data are immediately available for process control and optimization. This in turn lowers the quality cost of production, that is, the loss suffered when a batch of product... 

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