Heat Induced Changes of Peda as Determined by Microstructure and Texture

Scanning Electron Microscopy (SEM) was used to study the relationship between submicroscopic structure and macroscopic properties occurred during processing of peda, a popular heat desiccated Indian dairy confection. Various components of milk undergo complex interaction amongst themselves due to prolonged heat treatment and with the added sugar molecules. An investigation was therefore carried out to study the sub-microstructure of peda to determine the internal structure and better understanding of the typical body & texture of this traditional Indian sweet delicacy. The microstructure of peda reveals that the extensive heat treatment causes formation of casein-whey protein complexes which ultimately fused with lactose and sugar. The coalesced protein agglomerated as thick bridges. Large aggregates of lactose crystals and more void space was found in market peda which might be due to un-uniform kneading during processing. The textural properties differed markedly in laboratory and market peda. High hardness, fracturability, gumminess and chewiness and low springiness and cohesiveness of market peda might be due to extensive heating and lack of compactness. It was evident from SEM that the compactness of the network in market peda was lower as compared to laboratory samples and presence of scale or layer type structure in market samples indicated overheating of the product.