title: Effect of microwave heating on the quality characteristics of canola oil in presence of palm olein.
abstract: BACKGROUND
  Microwave heating is one of the most attractive cooking methods for food preparation, commonly employed in households and especially in restaurants for its high speed and convenience. The chemical constituents of oils that degrade during microwave heating do so at rates that vary with heating temperature and time in a similar manner to other type of processing methods. The rate of quality characteristics of the oil depends on the fatty acid composition and the minor components during heating. Addition of oxidative-stable palm olein (PO) to heat sensitive canola oil (CO), may affect the quality characteristics of CO during microwave heating. The aim of this study was to evaluate how heat treatments by microwave oven affect the quality of CO in presence of PO.
  
  
  METHODS
  The blend was prepared in the volume ratio of 40:60 (PO:CO, PC). Microwave heating test was performed for different periods (2, 4, 8, 12, 16 and 20 min) at medium power setting for the samples of CO and PC. The changes in quality characteristics of the samples during heating were determined by analytical and instrumental methods.
  
  
  RESULTS
  In this study, refractive index, free fatty acid content, peroxide value, p-anisidine value, TOTOX value, specific extinction, viscosity, polymer content, polar compounds and food oil sensor value of the oils all increased, whereas iodine value and C₁₈.₂ /C₁₆:₀ ratio decreased as microwave heating progressed. Based on the most oxidative stability criteria, PO addition led to a slower deterioration of CO at heating temperatures. The effect of microwave heating on the fatty acid composition of the samples was not remarkable. PO addition decelerated the formation of primary and secondary oxidation products in CO. However, effect of adding PO to CO on the formation of free fatty acids and polymers during microwave treatment was not significant (P < 0.05). No significant difference in food oil sensor value was detected between CO and PC throughout the heating periods.
  
  
  CONCLUSIONS
  Microwave heating caused formation of comparatively lower amounts of some degradative products in PC compared to CO indicating a lower extent of oxidative degradation of PC.
authors.affiliation: Department of Chemistry, Rajshahi University of Engineering and Technology, Bangladesh.
authors.forename: M Abbas
authors.initials: MA
authors.lastname: Ali
authors.affiliation: Department of Bioprocess Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia.
authors.forename: Zahrau Bamalli
authors.initials: ZB
authors.lastname: Nouruddeen
authors.affiliation: Department of Bioprocess Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia.
authors.forename: Ida Idayu
authors.initials: II
authors.lastname: Muhamad
authors.affiliation: Sime Darby Research Sdn. Bhd. Selangor, Malaysia.
authors.forename: Razam Abd
authors.initials: RA
authors.lastname: Latip
authors.affiliation: Sime Darby Research Sdn. Bhd. Selangor, Malaysia.
authors.forename: Noor Hidayu
authors.initials: NH
authors.lastname: Othman
mesh_terms: D003296:Cooking / Q000379:methods; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry*; D006358:Hot Temperature / Q000009:adverse effects*; D008872:Microwaves / Q000009:adverse effects*; D010084:Oxidation-Reduction; D000073878:Palm Oil; D010938:Plant Oils / Q000737:chemistry*; D000074262:Rapeseed Oil; D013997:Time Factors
chemical_list: D005229:Fatty Acids, Monounsaturated; D010938:Plant Oils; D000074262:Rapeseed Oil; D000073878:Palm Oil