Preservation of quality in bread presents two problems. Most commonly encountered problem is staling which starts within 24 hours of making the product and the other aspect is vulnerability to spoilage as it has high moisture content suitable for bacterial and fungal infection. Now comes the third dimension of bread quality as is being brought out by bakery scientists which highlights the susceptibility of bread to flavor damage because of oxidative chemical reactions taking place in the crumb as well as the crust. It is suggested that incorporation of some of the common antioxidants in bread formulations can arrest such deterioration for a few days.
"The researchers reported that oxidative changes occur in both crumb and crust during extended storage. The oxidative changes in the whole wheat bread were found to be relatively minor, however were significant enough to cause changes to flavour and odour, with attributes characterising the stored bread reported as 'aged', 'dusty', 'rancid', 'sickly sweet', and 'bitter'. The content of lipid hydroperoxides – a primary oxidation product – was found to be significantly higher in stored bread crumb compared to bread crust, and reached a maximum peak after 2-3 weeks of storage. Subsequently, the researchers found a decrease in lipid hydroperoxides after 4 and 5 weeks of storage, which they said indicates that the formation of secondary oxidation products was larger than the production of primary oxidation products. "Bread can be regarded as a product with a relatively high oxidative stability. Despite the high stability the present study clearly showed that oxidative changes occurred in both crumb and crust of whole wheat bread as a consequence of extended storage at room temperature," wrote Jensen and co-workers. "A decrease in the anti-oxidative capacity as a consequence of storage reflects a progress in the oxidative reactions depleting antioxidants … [The] quality of bread with extended shelf life may accordingly be improved by minimising oxidation" they added".
It is some what intriguing as to why this aspect of flavor deterioration had not come to the surface in spite of more than 100 years of research on bread making and the quality of the product. Probably such flavor changes may be hardly perceptible during the first 2-3 days within which bread is normally consumed. It is difficult to imagine that consumers will keep bread for days together as it is more vulnerable to staling, roping and molding. While staling can be reversed to some extent by heating to 60C or retarded by increased gluten level in the formulation or use of mono and diglycerides, bacterial and mold infection can be dangerous. Using preservatives to extend the life of bread is not considered practical because of significant changes in its sensory quality during storage.
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