The effect of supercritical fluid extraction on the shelf life and structure of pecans.

摘要

Pecans (Carya illinoensis) are very rich in oil, ranging from 55% to 70%, with a high degree of unsaturated fatty acids. The oil content of the pecans was reduced to approximately 22 to 28% using a supercritical fluid extraction method. A semi trained panel was used to evaluate the texture and flavor of both the non extracted and pecans extracted at 40°C and 80°C. The pecans were stored at retail conditions for a year to observe the changes in the quality of the pecans. The pecans also were stored in three different oxygen levels (2, 10, 21%) to study the effect on the quality. The structure of the pecans was studied using a transmission electron microscope (TEM) and a scanning electron microscope (SEM).; The panel of semi trained members evaluated the pecans (both extracted and non extracted) and concluded there was no significant difference in the acceptability between the samples. The storage study showed that the hexanal content, which is a byproduct of rancidity, was lower for the extracted pecans than the control pecans during storage. Sensory evaluations showed that the rancidity flavor was lower during storage for extracted pecans, indicating that the shelf life is increased when the oil content is decreased. The oxygen level did not have much effect on the flavor of the pecans stored at 2, 10 and 21% levels. The SEM of pecans that were extracted showed blisters on the surface while the non extracted kernels had a smooth surface. The TEM of the extracted pecans showed that the cells were broken while the non extracted pecans had intact cells. By lowering the oil content of the pecans the shelf life is prolonged.