Fat crystal network structures have a strong influence on properties of fat-based barrier layers

Mixtures of low and high melting fats (fractions of palm fat, palm kernel fat, and milk fat) were characterized after solidification with respect to solid fat content (SFC), firmness, barrier properties against moisture transport, and fat crystal network structure (FCNS). The method of detrended fluctuation analysis (DFA) was applied to quantify FCNS which was visualized using confocal laser scanning microscopy (CLSM). A broad range of firmness of solidified fat mixtures could be observed for comparable SFC confirming the influence of FCNS. Smooth FCNS without dense crystals indicate firmer networks and vice versa. A correlation between the scaling exponent from DFA and firmness was found. Moisture barrier properties of the fat mixtures differed for similar SFC, too. In this case, FCNS with dense crystals and larger areas of interconnected liquid fat resulted in the best barrier effect. Smooth FCNS were found in fat blends possessing only low resistance against moisture transport. For SFC>35% at 20 degrees C, a linear correlation between scaling exponent and moisture barrier effect was detectable. Practical applications: These results can be used to optimize fat mixtures with respect to their performance and define the fat crystal network structures which are required to obtain either high mechanical firmness of the solidified mixture or an efficient prevention of moisture transfer.