(727c) Optimizing Winterization Process of Nutritional Lipids By Rheological Studies

Triacyclglycerols (TAGs), saturated fatty acids and waxes present in nutritional crude oils crystallize at different temperatures and certain components impact the oil quality negatively by causing haziness or even sedimentation in the oil, and therefore needs to be removed during the winterization and cold filtration process. Nutritional crude oils containing DHA occasionally blinds chill filtration step during winterization due to the formation of a second morphology (needle-shaped) crystals causing slower throughput. Surprisingly, it was discovered that the formation of the needle-shaped crystals is detectable using a lab rheometer and viscosity kinetics, where the winterization process is mimicked in a scale down model. Needle crystal nucleation results in a second increase in viscosity after what appeared to be steady state was achieved, often 12 to 20+ hours into a holding cycle. Growth of needle crystals can be controlled based on the winterization process, holding times, cooling rate, final temperature, or a combination of various factors. In this study, differential scanning colorimetry (DSC) was used to study the thermal behavior of the DHA crude oil and rheological tests were run to measure viscosity values during winterization process to develop an optimized set of conditions to prevent formation of needle crystals. As an example, there was a secondary increase in viscosity, resulting in the oil with a 23% higher viscosity observed after 20 hours hold time at winterization temperature of 8 °C and morphology of the needle crystals were also confirmed via microscopy. Effect of lower shear rates on formation of different crystal morphologies were also studied. The effects of winterization parameters including hold times, cooling rate, final temperature, and shear rates were investigated and the optimized condition was defined for filtration process, leading to improved throughput, and enhanced finished nutritional oil characteristics, such as reduced turbidity and cloud point, for customers.