Matrix Effect on Fat Crystallization in Laminated Bakery Products
The impact of a croissant matrix on fat crystallization was determined by analyzing the polymorphism using powder x-ray diffraction (XRD), solid fat content (SFC) by pulsed nuclear magnetic resonance (p-NMR) and melting behaviour by differential scanning calorimetry (DSC). Roll-in shortenings of varying composition were used to prepare croissants. XRD revealed polymorphic conversion (from β' to the β form) occurs when fat is baked within the matrix, and the extent of conversion depends on the fat’s composition. In addition, the fat contained within a croissant will have a significantly lower SFC and a greater temperature is required for complete melting. The same fats were then baked in the presence of isolated croissant components (wheat starch, gelatinized wheat starch, gluten and a formed gluten network) and the cooled samples were analyzed using the same methods. Overall, the results suggested that changes in crystallization behaviour are caused by an interaction between fat and gelatinized wheat starch.