BLT Stages

This project is about developing a method for determining the emulsion capacity of proteins in oil-in-water emulsions. The generated data are used in a bigger project of the internship. The internship is in a company that is known for margarines and oils, so it will be used to determine what protein will be selected in future processes.   

As of today, there is still no standard method developed by Vandemoortele for making and analysing emulsions and emulsifiers. A standard method means that every product (emulsifier) undergoes the same process under the same conditions. This standard method is used for evaluating the emulsion capacity of different proteins.

This method development means that first, a starting method is selected. This starting method for making an emulsion involves a mixing treatment with the Ultra Turrax of three minutes with 30 seconds at 10000 rpm and the rest of the time at 15000 rpm. Afterwards the emulsion is analyzed for heat stability, protein solubility and internal droplet size.

All parameters are tested so the method is optimized for showing the best difference in emulsion capacity between the proteins. After the optimalisation of making an emulsion, the method for analysing an emulsion is also optimized.

During the method development, every parameter is tested to analyse its influence on the emulsion capacity difference between proteins. The protein difference is increased by increasing the protein concentration and Turrax speed. The oil concentration, Turrax time and emulsion volume are not tested with different proteins. The refractive index and droplet form have no influence on the difference.

After testing all parameters, there is a standard method made. All parameters have an influence on the protein difference. Some are bigger than others. After more tests are made, this can be used as a standard method. These tests consist of more reproductive and distinctive tests because not every parameter is tested on different proteins.

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.