Changes in pumpkin seed oil during heating

Abstract

Purified pumpkin seed oil was heated either continuously or intermittently for 10 hours at 180±5°C, and occurring changes were evaluated. Free fatty acids (FFA), peroxide value (PV), colour, polar compounds and viscosity increased, while iodine value and unsaturation decreased. Intermittent heating had the more pronounced effect on these changes. Fatty acid profile determination showed non-significant changes in palmitic (C16:0), arachidic (C20:0) and oleic (018:1) acids during heating. Statistically significant decreases were observed in linoleic (C18:2) acid content. These decreases also caused significant increases in stearic (C18:0) acid content. Of the tocopherols, only α-tocopherol was detected, which was reduced during purification and bleaching to 33%. The 10-hour continuous and intermittent heating caused an additional 14 and 23 % loss respectively. High correlations were obtained between FFA and polar compounds, PV and polar compounds, viscosity and polar compounds, IV and unsaturation, and linoleic acid and polar compounds.

Keywords

• continuous heating
• intermittent heating
• physicochemical properties (changes)
• pumpkin seed oil