RMIT University, Australia
Title: Molecular understanding of the interactions between milk protein, phenolic compounds and lipid oxidation products in liquid oat systems
Jasmeet Kaur is a current PhD student at the RMIT University, Melbourne, Australia, under the supervision of Professor Stefan Kasapis. Her research is focused studying the effect of ultra-high temperature processing, storage condition and interactions of the micro constituents of oats with the co-soolutes such as milk protein, sucrose and oil in a model beverage system.
To increase the antioxidant consumption in human diet, the food industry aims to develop thermally processed products, including beverages containing a high content of oat. Nevertheless, the nutritional value and sensory appeal of liquid-like products with oat might be affected when subjected to ultra-high temperature (UHT) treatment followed by prolonged storage at ambient conditions. For instance, ferulic acid, which is found attached to arabinoxylans, might undergo thermal decarboxylation leading to the formation of 4-vinyl guaiacol (PVG), a compound of very low sensory threshold value responsible for the development of phenolic off-flavour. In addition, heat treatment promotes lipid oxidation processes leading to rancidity via the production of volatiles including hexanal and pentyl furan. In order to evaluate nutritional availability and organoleptic acceptability, we have prepared model systems of liquid breakfast by incorporating oat grain to formulations in the presence of milk protein, sucrose and canola oil. Molecular interactions amongst these ingredients were examined following UHT processing during a twelve-week shelf life. Experimental protocol included application of analytical technology like HPLC (phenolic acids and avenanthramides), 2-D GC for free fatty acids, GC-MS for the evaluation of volatile lipid oxidation compounds, FTIR with fluorescence spectroscopy, surface tension and dynamic light scateering ( mastersizer and zetasizer) for patterning the complexation of micronutrients amongst chemical compounds. It was found that the nature of interactions (physical or chemical) between protein and phenolics, and protein with free fatty acids or volatiles is affected considerably by sample composition, thermal treatment and storage conditions having an unexpected impact on the quality and health aspects of these product concepts.