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Mechanical properties of bread crust by puncture test and the effect of sprayed enzymes

Abstract:

Texture analysis is widely used for assessing objectively the characteristics of food products. Different texture analysis of foods has been performed through compression, penetration, acoustic and profile analysis. In cereal based foods, namely crusty bread, the fracture behaviour of the crust is the main perceived characteristic associated to bread freshness, but it is rapidly loss after baking. The objective of this study was to evaluate the test conditions (speed and probe), their incidence on the mechanical parameters (puncturing force, spatial frequency of structural ruptures, specific force of structural ruptures, and crispness work of the bread crust) and their relationship with the crust microstructure. The validity of the test performance for analysing bread crust was examined in different enzyme treated bread crust. For that purpose, enzyme solutions (glucose oxidase, amyloglucosidase, protease) were applied onto the surface of partially baked breads before final baking. Low speed puncture test gave information about the cellular structure of the crust whereas high punch cross section was associated to compression behaviour. Enzymatic treatment of the crust affected significantly (p<0.05) the mechanical fracture properties, indicating a significant modification at microstructural level. Microstructure analysis confirmed that enzyme treatment modifies the crust structure.