Identification of formulation effects on cake softness using a technique combining alveolar structure analysis with mechanical properties characterization

Cake softness is a sensory descriptor not clearly defined. It is difficult to instrumentally characterize softness. Generally it is limited to the analysis of the mechanical properties of the aerated crumb. Indeed, thickness of alveolar walls, size of alveoli and openness of the crumb structure are all structural criteria which may have an effect on mechanical properties and thus, plays a key role in textural properties of soft cakes. The aim of this study was to characterize cake softness by combining alveolar structure analysis with aerated crumb and cell walls mechanical properties analysis. First investigations were made on quantifying the impact of formulation (including ingredient storage) on cake alveolar structure by using an image processing technique based on the mathematical morphology method combined with data analysis by Principal Components Analysis (PCA). PCA simplified the interpretation of the image processing results by classifying crumb structures according to their granulometric curves. Product mapping was depending on two axes that could be related to crumb fineness and heterogeneity. It appeared that flour storage temperature and time and emulsifier quality play a major role on cake crumb fineness and heterogeneity. Further investigations on mechanical properties of both aerated cake crumb and alveoli walls were then carried out to better understand effects of formulation on mechanical properties of cake crumb. Emulsifiers were found to have an effect not only on alveolar structure (alveoli size and heterogeneity) but also on aerated crumb mechanical properties and on cell walls firmness. Therefore, it was possible to explain which mechanical properties are due to either aerated cake structure or cell walls firmness.