Total polar compounds

Aliphatic hydrocarbons Aromatic compounds Total polar compounds... 

Virgin olive oil shows a remarkable resistance to oxidation and polymerisation during domestic deep-frying of potatoes or in other uses at frying temperatures. Compared to vegetable oils such as sunflower, cottonseed oil, com and soybean oil, olive oil shows a significantly lower rate of alteration as demonstrated by measurements of viscosity, total polar compounds and loss of... 

Quantitation of FA composition by gas-liquid chromatography of methyl esters is useful for the monitoring of unsaturated FA. Losses of PEFA follow the increase in total polar compounds. Near the rejection point (27% TPC), 10 to 15% losses of PEFA can be observed. 

Quantitation of total polar compounds (TPC) is the basis of legislation in many countries for the control of used frying fats. The method is gravimetric and based on the adsorption of polar compounds onto a silica gel column. Limits up to 27% have been set for TPC in countries where frying oils are regulated. There are approved methods (lUPAC, AOAC) for TPC determinations. TPC can also be determined with Sep-Pak cartridges. An alternative technique uses the latroscan thin-layer chromatography/flame ionization system (Sebedio et al., 1987). 

Oils Storage (weeks) Total polar compounds Ox TG monomers TG dimers TG polymers DG FA... 

Table 12.15. Effect of dimethylsiloxane (DMPS) on total polar compounds and a-tocopherol content in frying oils and food lipids ...

A comparison of the formation of total polar compounds (TPC) showed no significant differences in the rates of TPC formation between LLCO and HOCO... 

FIGURE 1.6 Total polar compounds (TPC) over frying time for canola oils. Oils with the same letter as subscript displayed no significant differences in rates of TPC formation at p < 0.05. (From Normand, L., Eskin, N.A.M. and Przybylski, R. 2001. J. Amer. Oil Ghent. Soc. 78 369-373. With permission.)... 

In another frying trial by Xu et al. (1999), three HOLL canola oils with different levels of linolenic acid and HOSO were compared with commercial PO. The oils were heated over a period of 80 h at 190°C by frying potato chips. Fatty acid analysis, iodine value, colour index, dielectric constant, free fatty acids and the total polar compounds were used for the assessment of the suitability of the oils. Additionally, a sensory evaluation was carried out... 

In a later paper, Xu et al. (2000) found slightly different results. PO was compared with HOLL canola oil as well as two blends of canola oil and PO (70 30 and 30 70, respectively), in two 80 h frying trials. In all oils, the amount of free fatty acids and total polar compounds increased significantly during the processing. HOLL canola... 

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