Response and sensitivity of lipid related molecular structure to wet and dry heating in Canola tissue

Abstract

Heat treatments are used to manipulate nutrient utilization, availability and functional properties. The objective of this study was to characterize any molecular level changes of the functional groups associated with lipid structure in canola (Brassica) seed, as affected during the wet and dry heat treatment processes using molecular spectroscopy. The parameters included lipid CH3 asymmetric (ca. 2970–2946cm−1), CH2 asymmetric (ca. 2945–2880cm−1), CH3 symmetric (ca. 2881–2864cm−1) and CH2 symmetric (ca. 2864–2770cm−1) functional groups, lipid carbonyl CO ester group (ca. 1774–1711cm−1), lipid unsaturation group (CH attached to C–C) (ca. 3007cm−1) as well as their ratios. Hierarchical cluster analysis (CLA) and principal components analysis (PCA) were conducted to identify molecular spectral differences. Raw canola seeds were used for the control or autoclaved at 120°C for 1h (HT-1: wet heating) or dry roasted at 120°C for 1h (HT-2: dry heating). Molecular spectral analysis of lipid functional group ratios were not significantly changed (P>0.05) in the CH2 asymmetric to CH3 asymmetric stretching band peak intensity ratios for canola seed. Both wet (HT-1) and dry heating method (HT-2) had no significant effect (P>0.05) on lipid carbonyl CO ester group and lipid unsaturation group (CH attached to CC). Multivariate molecular spectral analyses, CLA and PCA, were unable to make distinctions between the different treatment original spectra at the CH3 and CH2 asymmetric and symmetric region (ca. 2992–2770cm−1), unsaturated lipids band region (ca. 3025–2993cm−1) and lipid carbonyl CO ester band region (ca. 1774–1711cm−1). The results indicated that both dry and wet heating of given intense had no impact to the molecular spectrum in lipid related functional groups of canola seed, and was not strong enough to elicit heat-induced changes in lipid conformation.