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Influence of ozone treatment on sensory quality, aroma active compounds, phytosterols and phytosterol oxidation products in stored rapeseed and flaxseed oils
Water content, critical micelle concentration of phospholipids and formation of association colloids as factors influencing autoxidation of rapeseed oil
AbstractBACKGROUNDThe exact mechanism of lipid autoxidation in vegetable oils, taking into account physical aspects of this phenomenon, including the role of association colloids, is still not fully understood. The purpose of this study was to consider changes in moisture content and DOPC phospholipid (1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine) critical micelle concentration (CMC) in rapeseed oil during autoxidation as well as to find the relationship between these parameters and the accumulation of primary and secondary lipid oxidation products.RESULTSThe experiments were performed at initial oil humidity 220 ppm and 700 ppm, with DOPC below and above CMC. The increase in water concentration was favored by the presence of phospholipids above CMC and, at the same time, high initial water level, which favored oxidation processes and the creation of amphiphilic autoxidation products. At relatively high water level and low amphiphilic DOPC concentration, the growth of water content does not affect the concentration of oxidation products.CONCLUSIONAmphiphilic substances play a significant role in increasing the water content of oil. Autoxidation products may reduce CMC of DOPC, but water is able to compensate for the CMC‐reducing effect of oxidation products. The presence of association colloids and initial water content play a crucial role in the oxidation process of rapeseed oil. The increase in water concentration does not cause a sufficiently large increase in the number of micelles or sufficiently significant changes in their structure to effect an increase in the level of oxidation products. The formation of micelles requires an appropriate content of both water and amphiphilic substances derived from seeds (phospholipids). © 2021 Society of Chemical Industry.
Changes in Oil Quality and Peroxidase Activity during Germination of Rape Seeds and Mustard Seeds
Vegetable oils are selected by consumers based on the presence of multiple bioactive substances, including polyunsaturated fatty acids, sterols, and tocopherols. Another important factor in oils is their quality. This research involved analyzing the oils quality and quantity of bioactive substances obtained from rape seeds and white mustard seeds that underwent germination. The quality of the oils was compared by determining the acid and peroxide values. Germination lowered the peroxide value by 86.3% and 71.4% for rapeseed oil and mustard oil, respectively. This was due to the germination step of the seed use oxygen, which was the substrate for lipid peroxidation. The activity of peroxidase increased by 95% for rapeseed oil and 94% for mustard oil during germination. An increase in the amount of polyunsaturated fatty acids in mustard oil also was noted during germination.