To make puff pastry, it is important that the margarine has the right functionality. This means that the margarine is preferably not too hard or too soft, maintains its plasticity and results in the desired height and shape of the baked pastry. The functionality of a bakery margarine is assessed by manual kneading and is scored on different parameters such as initial hardness, plasticity and hardness after kneading. However, this method is rather subjective and requires regular calibration. Therefore, the aim of this thesis is to develop a way to measure and hopefully predict the functionality of a margarine in puff pastry using standardized instrumental measurements.
Commercially available bakery margarines were characterized by different analytical tools and laminated in a puff pastry dough. Using a multiple extrusion cell, connected to the TA.XTplus Texture Analyser, the worksoftening of the margarine was measured. This method and especially the data processing was not yet optimal and still needed further research. To analyze and measure the layered structure of the unbaked puff pastry using the microscope, a quantitative method needed to be developed.
In addition, the initial hardness was measured with the TA.XTplus Texture Analyser using the cone measuring probe. The solid fat content and the composition of fatty acids were also measured using pulse nuclear magnetic resonance and gas chromatography with a flame ionization detector, respectively. These analyses provided extra information that could help to make connections between the properties of the margarine and the results of the kneading and baking trials.
The method and data processing of the worksoftening measurements have been optimized. The relative standard deviations have gone down and the parameters that define the worksoftening are shown to correlate with the puff height. A quantitative method to measure the fat and dough layers of the unbaked puff pastry has been established and is shown to be repeatable. The most important information lies in the standard deviations of the fat layers. These standard deviations seem to correlate with the parameters of the worksoftening and the puff height. Other correlations between the results have been found, but it is necessary to measure a wider range of different margarines to further analyze these connections.
Nowadays Vandemoortele customers desire functional products with lower saturated fats. The functionality of fat based food products are mainly determined by the crystallization of fats. However, up to now an industrial method that offers the potential to study crystallization of fats under shear conditions is still lacking. To this end a study was conducted to evaluate the characteristics and crystallization properties of different palm based fats, commonly used in plastic margarins in puff pastry products. Particularly the interesterification of palm fractions and the influence of external factors on the crystallization behaviour were studied.
First a physicochemical characterization of the different fats was determined by nuclear magnetic resonance, gas chromatography and liquid chromatography. In this way, the chemical composition in relation to its crystallization properties can be compared.
The crystallization behaviour of fats was studied by differential scanning calorimetry (DSC) and rheology. DSC measures exo- and endothermic differences in fats, which represents the polymorphic changes in their crystallization behaviour. Using DSC, the isothermal crystallization kinetics of the different palm fats were studied at twenty degrees. Using oscillatory rheology, information of both primary crystallization and microstructural crystal network development can be obtained. The aim of applying a rheology method was to understand the influence of processing parameters on the network formation of crystallized fats.
Data provided by this research shows that interesterification causes a rearrangement of fatty acids in triglycerides. Moreover, the interesterification effect is fat-dependent and varies on the basic composition which fats consist of. Rheology and DSC have both advantages and limitations, which makes them complementary to assess the crystallization development. In the future, it will be important to determine the qualities of fat blends in order to improve the processing parameters of plastic margarines.
Prins Albertlaan 79