Roasting effects on fatty acid distribution of triacylglycerols and phospholipids in the kernels of pumpkin (Cucurbita spp) seeds

Abstract

In this study, changes in fatty acid distributions of pumpkin seeds (Cucurbita spp) in the course of the roasting process were investigated. Whole pumpkin seeds were exposed to microwaves for 6, 12, 20 or 30 min at a frequency of 2450 MHz. The kernels were separated from the seeds, and the lipid components and the fatty acid distributions of triacylglycerols (TAGs) and phospholipids (PLs) were analysed by a combination of thin layer chromatography and gas chromatography. Major lipid components were TAGs, free fatty acids (FFAs) and PLs, while steryl esters and diacylglycerols were also present in minor proportions. The greatest PL losses (p < 0.05) were observed in phosphatidyl ethanolamine, followed by phosphatidyl choline or phosphatidyl inositol. With a few exceptions, significant differences (p < 0.05) in fatty acid distributions occurred when the seeds were microwaved for 20 min or more. Nevertheless, the positional characteristics of fatty acid distributions in the TAGs were still retained after 20 min of roasting: unsaturated fatty acids were predominantly concentrated in the sn-2-position, and saturated fatty acids primarly occupied the sn-1-or sn-3-position. These results suggest that no significant changes in fatty acid distribution of TAGs and PLs would occur within 12 min of microwave roasting, thus ensuring that a good-quality product would be obtained.

Stereospecific Analysis of Triacylglycerols as a Useful Means To Evaluate Genuineness of Pumpkin Seed Oils: Lesson from Virgin Olive Oil Analyses

“…Another fact that should be taken into account is the way pumpkin seeds for S7 were pressed; they were cold pressed. From the data shown one could conclude the roasting process influences the triacylglycerol composition as previously stated ; however, Reference 8 report only very slight differences in linoleic acid composition before and after the roasting process (54.6 vs 54.0%).…”

Oxidation stability and compositional characteristics of oils from microwave roasted pumpkin seeds during thermal oxidation

“…Of course, each oil has a characteristic pattern of TAGs, and the properties of a particular oil are determined mainly by the abundance of different TAG molecular species. [16] The changes in stability, composition, and distribution of fatty acids in triacylglycerols of oil, which occur during conventional oven roasting [17][18][19] and microwave roasting [20,21] of pumpkin seeds (Cucurbita pepo L.), have been well investigated. However, there is very little or no information available on the influence of microwave roasting on oxidative stability and composition of pumpkin (Cucurbita maxima Duch.)…”