Food degradation processes

Packaging can influence the need for additives to varying degrees, sometimes dramatically as with the vacuum packaging of fresh chilled beef which confers an additive-free storage life of over 6 weeks and makes international trade in this product possible. 

1 Microbiological spoilage. Foods that have been previously steril- 

Smith (ed.), Technology of Reduced-Additive Foods Chapman Hall 1993 

The Maillard reaction (non-enzymic browning) is prevented by the addition of sulphur dioxide, either as the gas or as sulphite. Packaging that reduces the loss of SO2 due to oxidation or permeation (Davis et al., 1973) can decrease the need for this additive. 

Senescence is triggered naturally by the hormone ethylene, which is produced as a result of injury or when the produce starts to ripen. Removal of ethylene as it is produced can therefore retard senescence. 

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Heavy metals and to some extent their derivatives are among the indestructible pollutants that are neither subject to bacterial attack nor other breakdown or degradation processes and are thus permanent additions to the environment.12 14 Accordingly, their concentrations most often exceed the permissible levels normally found in the environment soil, water ways, and sediments, ending up in the food chains. Following these events, heavy metals and/or their derivatives accumulate in the plant and animal life where they profoundly disrupt biological processes, causing various... 

In the field of bioremediation, oxidoreductases are considered to be excellent biocatalysts for environmentally friendly processes. Laccases and peroxidases are widely used to treat effluents from pulp/cotton mills, food/fruit processing plants and breweries [1, 2, 37]. Laccases, peroxidases and other oxygenases are also being studied for their abihty to degrade hazardous coal substances, especially the sulfur-containing components, and in the treatment of industrial waste and contaminated soil and water in the transformation of xenobiotics, polycycHc aromatic hydrocarbons and other pollutants (biodetoxification and biodecontamination)... 

Household and municipal solid waste compost also contains Cd that had its origins in agricultural soil. Composts consist of food wastes that have been microbially degraded. The food wastes contain trace amounts of Cd, most of which originated from the soil (Adriano, 2001). The degradation process results in compost with a much higher Cd concentration than the food wastes that went into it. Just like the farmyard manure, repeated applications of compost onto fields that were not the source of all of the Cd in the compost will result in localized increases in soil Cd concentration. However, the agricultural soils affected by compost application are in the minority, since compost is applied mainly to soils around urban areas. 

His next appointment was as Senior Scientific Officer to the Institute of Food Research, Norwich, UK and Portland, Oregon, USA, with dual responsibility for an R D programme investigating degradation processes in landfill. The objective of this assignment was to enhance landfill gas and energy production. 

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]. 

As amply discussed in Chapter 2 [Secs. Ill, IV], proteins from different sources can be modified to produce a wide variety of PBS. Some of the techniques used in protein modification have been indicated in Chapter 5 [Secs. II-VII], with reference to PBS produced via a degradation process such as proteolysis and deamidation, in addition to the cases of the surfactants produced by covalent attachment of nonprotein moieties. Enzymatic modification of proteins with specific reference to food application has been discussed in Chapter 1, Section II.B. Briefly, it was hypothesized that by reacting a hydrophilic protein as the substrate with highly hydrophobic amino acid ester as the nucleophile, a product with amphiphilic properties would result from the localized regions of hydrophobicity [76]. To obtain adequately hydrophilic proteins as substrates, succinylation could be used to modify the proteins prior... 

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