FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY

Authors

MAŁGORZATA WRONIAK, AGNIESZKA RĘKAS, ILONA PIEKARNIAK

Title

Effect of packaging type and storage conditions on selected quality properties of cold-pressed rapeseed oil

Abstract

The objective of the research study was to determine the effect of packaging material and storage conditions on some selected quality properties of cold-pressed rapeseed oil. The scope of the research study comprised the pressing of oils from rapeseed seeds of ‘Monolit’ cultivar with the use of a Farmet screw press, the oil refining using natural sedimentation and decantation, and the quality analysis of freshly coldpressed oils and of cold-pressed oils stored under various conditions and in different packages (made of brown glass and PET) over a period of 12 months. Under the oil analysis the following was determined: degree of hydrolysis, primary and secondary oxidation degree of lipids, oxidation stability using a Rancimat test at a temperature of 120 °C, and consumer acceptance level; also, a sensory assessment of the pressed oils was performed with the use of a profiling method. It was confirmed that the storage conditions significantly affected the rate of oxidative changes in cold-pressed oils. The access to oxygen and the storing of rapeseed oil at 20°C over a period of 12 months caused the level of peroxides (PV) and aldehydes (AnV) to strongly increase (respectively, from 2.9 to 28 ÷ 30 meq O2/kg and from 0.6 to 1.2 ÷ 1.4) and the length of induction period to decrease (from 3.6 to 2.5 h), the rancid sensory attribute of oil to appear already between the 2nd and 3rd month of oil utilization (at PV ranging between 9 and 11 meq O2/kg and at AnV ranging between 0.8 and 0.9). The oil stored at a temperature of 20° C in unopened bottles oxidized slower than the oil in the bottles with the periodic exposure to oxygen, and the slowest oxidative changes were reported in the oil stored under the refrigeration conditions. It was found that the unopened brown packages (both of glass and PET) guaranteed that the good chemical properties of oil (PV ranging between 5 and 8 meq O2/kg and AnV ranging between 0.7 and 0.8), length of induction period, and sensory properties of oil were comparatively well maintained until the end of the one-year storage period. As regards the oils in brown packaging and stored with and without the exposure to light, no differences in quality thereof were reported.

Keywords

cold-pressing, rapeseed oil, packaging, storage, quality

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