Erica R. Baümler

Emulsions of sunflower wax in pectin aqueous solutions: Physical characterization and stability

The knowledge of the stability and physical properties of film-forming solutions is necessary for optimizing the process design of films. In order to evaluate their applicability for the production of edible films, the rheological and microstructural properties, particle size and physicochemical stability of aqueous emulsions of low methoxyl pectin and sunflower waxes from normal and high-oleic hybrids were assessed. Emulsions were prepared with different pectin concentrations (1, 2 and 3% w/w) and wax proportions (0.1, 0.2 and 0.3 g/g pectin). The rheological behavior was best described by the power law model. The values of the behavior index (n) were close to 1, exhibiting a behavior close to Newtonian fluids. The addition of waxes caused an increase in viscosity and shear stress. The particle size of the emulsions made with waxes from high-oleic sunflower was smaller than those from the normal hybrid. In most cases, size distributions with greater height and less amplitude were obtained, mainly when the pectin content was higher. Confocal images allowed to observe the presence of waxes and their dispersion in the pectin matrix. Destabilization phenomena such as sedimentation, coalescence and creaming were observed at long test times independent of the wax origin. These results evidence the potential use of these emulsions for the manufacture of edible films.

Effect of Different Treatments in Dehulling Ability of Safflower Seeds (Carthamus tinctorius L.)

In the oil industry, partial dehulling of seeds before the oil extraction constitutes a relevant stage of process and this could affect both the quality of the products and the industrial capacity. The decrease of moisture content in seed of oil crops can improve the ability of seed dehulling considerably thus to benefit the process of oil extraction. The dehulling process for safflower seeds is not often utilized due to its low efficiency and difficulties. The objective of this work was to determine the optimum moisture content for the dehulling of the safflower seed considering the fine production during seed dehulling. Another aim was to explore the effect of thermal pre-treatments on the seed dehulling ability. Dehulling ability was defined as the ratio (%) between the proportion of hull mechanically extracted and the real proportion of seed hull. A decrease in the moisture content of seeds increases not only their ability for dehulling but also the amount of fines originated. The optimum moisture for the process (maximum dehulling, minimum fines originated) carried out in one and two stages was the same (3,5%), getting the dehulling of about 37% for the process carried out in one stage and of 79% for the process in two stages. The dehulling ability of safflower seeds was affected, in great measure, for superior temperatures to the reference (21oC), presenting an irregular behavior. The same one implies that for temperature lees of about 100 °C, the dehulling ability is smaller that for reference temperature, increasing quickly for higher temperature. Cooling the safflower seeds previously at -5°C allowed increasing the dehulling ability respect to the obtained at the reference temperature, operating with one or two stages. The obtained results suggest that establishing strategies of handling of the seeds, in the stages of dehulling and extraction of oil, will optimize the process on the whole.