Oxidation food quality

CHOPRA M, MCLOONE u L, o neill m, WILLIAMS N and THURNHAM DI (1996) Fruit and vegetable supplementation - effect on ex vivo LDL oxidation in hiunans , in Kumpulainen, J T and Saonen, J T (eds), Natural Antioxidants and Food Quality in Atherosclerosis and Cancer Prevention, Cambridge, Royal Society of Chemistry, 150-55. 

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. 

Sometimes, in different systems, the oxygen presence is undesirable because of its reactivity and tendency to oxidize the contact materials that leads to corrosion of metallic materials or depreciation of food quality. Also oxygen could inhibit different chemical reactions or could interfere in different analysis (RES, polaroghaphy, etc.). 

Food-derived anticarcinogens, conjugated dienoic derivatives of linoleic acid, 262-270 Food quality health concerns, 5-6 maintenance by natural and synthetic compounds, 56-76 molecular s proaches to study, 1-6 related to antimicrobial peptides, 303-318 Foodbome pathogens, ionizing radiation, 296-298 Free radical(s) beef flavor peptides, 89-91 oxidation generating system, 88-89,91/ protein composition, 88-89,91/... 

B. M. Cordero, and M. Forina, Electronic Nose Based on Metal Oxide Semiconductor Sensors as a Fast Alternative for the Detection of Adulteration of Virgin Olive Oils, Anal. Chim. Acta 2002,459, 219 C. L. Honeyboume, Organic Vapor Sensors for Food Quality Assessment, J. Chem. Ed. 2000, 77, 338 E. Zubritsky, E-Noses Keep an Eye on the Future. Anal. Chem. 2000, 72. 

Beside BAs, low-molecular-weight alkylamines, commonly used as indicators of food quality, can also be present in fish muscle. Tri- and dimethylamine (TMA and DMA) are produced by bacterial reduction of the osmoregulatory substance trimethylamine oxide (TMAO) in fresh marine fish and by enzymatic reduction in frozen storage of gadoid fish (cod, cusk, hake, pollack), with concurrent formation of formaldehyde. 

Biosensors can also represent a good method to evaluate the antioxidant status through the measurement of biomarkers, i.e., biological molecules whose chemical structure has been modified as a result of an oxidative stress condition [118]. The usefulness of biosensors to evaluate the antioxidant status lies in their ability both to improve food quality and provide early indication of some disease, or its progression, in a noninvasive way to evaluate the effectiveness of the antioxidant therapy. 

It is claimed that commercially-available ultrasound equipment can measure the following quality parameters of dairy products levels of solids, solids non-fat (SNF), protein, water and fat solid fat content (SFC), colloidal stability, gelation point, adulteration with oil, particle size, particle size distribution, oil composition, protein denaturation and fat oxidation. This incomplete list represents an impressive contribution towards the solution of food quality measurement although the present authors are slightly skeptical regarding some of these claims. In this review only those applications will be addressed which are regarded as robust. 

Xiong, X.L. 2000. Protein oxidation and implication for muscle food quality. In Antioxidants in Muscle Food, 1st edn. (Decker, E.A., Faustman, C., and Lopez-Bote, C.J., eds.), pp. 85-111. John Wiley Sons, Inc. New York. 

A number of sensor arrays consisting of an assortment of commercial metal oxide gas sensors have been reported [45 7], For controlled tests, the sensors are mounted in an air-tight chamber fitted with gas inlets and outlets for controlled gas flow. Each sensor s heating element is controlled externally and resistance changes of the gas sensors are monitored by a computer data acquisition system. A significant effort in this area exists at the University of Warwick, Coventry, where for many years, sensor arrays, made from discrete Sn02 sensors or miniature integrated sensors, have been studied for ultimate application to food quality and food process control [47, 48]. 

During lipid oxidation, the primary oxidation products that are formed by the autoxidation of unsaturated lipids are hydroperoxides, which have little or no direct impact on the sensory properties of foods. However, hydroperoxides are degraded to produce additional radicals which further accelerates the oxidation process and produce secondary oxidation products such as aldehydes, ketones, acids and alcohols, of which some are volatiles with very low sensory thresholds and have potentially significant impact on the sensory properties namely odor and flavor [2, 3]. Sensory analysis of food samples are performed by a panel of semi to highly trained personnel under specific quarantined conditions. Any chemical method used to determine lipid oxidation in food must be closely correlated with a sensory panel because the human nose is the most appropriate detector to monitor the odorants resulting from oxidative and non-oxidative degradation processes. The results obtained from sensory analyses provide the closest approximation to the consumers approach. Sensory analyses of smell and taste has been developed in many studies of edible fats and oils and for fatty food quality estimation [1, 4, 5]. 

Selected metal anionic forms such as arsenic species are toxic compounds and their presence must be detected at very low levels. Similar to inorganic arsenic species, simultaneous determination of selenite and selenate, as well as Cr(III)/Cr(VI), provides important information about oxidation states and their influence on food quality and human health. 

More sophisticated statistical treatments of sensory data have been more commonly applied in studies of multiple factors of Upid oxidation on quality of foods, including Multivariate and Principal Component analyses. These procedures attempt to simplify complex relationships of several factors and sets of data into more understandable levels. Multivariate analysis is based on the fact that one measured property generally depends on more than one factor and the classical statistical univariate methods dealing with just one variable at a time are inadequate to analyse complex data. 

Each antioxidant evaluation should thus be carried out under various conditions of oxidation, using several methods to measure different products of oxidation related to real food quality. There cannot be a short cut approach to determining the activity of antioxidants. Various testing protocols should consider the following parameters and recommendations ... 

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