Edible Plant Oils Research Articles

Reasons for the High Proportion of Pheophytin in Edible Plant Oils

To reduce the pheopytin (Phy) level in oils, it is necessary to understand the reasons of the high proportion of Phy in refined edible oils. In this investigation, the compositional changes in chlorophyll (Chl) and Phy during extraction and some refining processes were evaluted by photofluorometric analysis.The composition of Chl pigments in crude oils was examined when Canola seed oil was extracted with 6 kinds of organic solvents. The proportion of Phy was found to be the highest (97%) in oil extracted with n-hexane, but 38% in hexane-ethanol (3 : 1) extracts, and 13 % in chloroform-methanol (2 : 1) extracts. Especially, when the residue following extraction with n-hexane was further extracted with chloroform-methanol (2 : 1), the proportion was only 3%. From these results, it is concluded that the use of n-hexane as a solvent reduces the extraction of Chl from oil seeds.Next, Canola seed oil was extracted with n-hexane for different extraction times and at different temperatures. Moreover, the changes in Chl during acid treatment of the crude oil were investigated in a model system. A portion of the Chl was converted into Phy during heat or acid treatments. However, in our previous study, a relatively constant compositional ratio between Chl pigments was observed in rapeseed oils throughout the process of mass production. The conversion of Chl to Phy during heat or acid treatment in model experiments may thus be assumed insignificant in practical refining for mass production.

Simultaneous Fluorometric Estimation of Chlorophylls and Pheophytins in Refined Edible Fats and Oils

It has been believed that chlorophylls are not remained in refined edible fats and oils, because their contents are below the limit of detection by spectrophotometric analysis. In this experiments, photo fluorometric quantification was investigated to evaluate simultaneously the content of chlorophylls and pheophytins in refined edible oils.Chlorophylls a and b, and pheophytins a and b were prepared respectively from acetone extracts of spinach and/or followed by the treatment of oxalic acid. Sixteen mililiters of actone solution of each component (concentration ca. 0.15mgl) was added into 3.64g of blank oil, which was prepared through the removal of photosensitizer in edible plant oils by using a activated carbon-Celite column. By the measurement of fluorescence intensity in four measurement systems (Ex 425-Em 663, Ex 454-Em 646, Ex 404-Em 670 and Ex 434-Em 655nm) by spectrophotofluorometer, the following calculation formulas were introduced;Chl a=(10.8F663425+0.307F646454-3.30F670404-4.91F655434)×10-3mg/kg oilChl b=(0.566F663425+5.09F646454-0.199F670404-0.950F655434)×10-3Phy a=(-8.09F663425-0.214F646454+11.7F670404+2.74F655434)×10-3Phy b=(-4.81F663425-1.71F646454+1.23F670404+7.92F655434)×10-3In the case of practical evaluation of refined edible oils, the fluorescence intensity of blank oil was subtracted from that of sample solution, dissolving 3.64g oil in 16ml of spectrum grade acetone. Thus, the indentity and concentration of four components may be accurately and rapidly determined within the concentration range from 0.05 to 1mg/kg oil as the total chlorophylls.As the results of fluorometric quantification on several refined edible oils, it was confirmed that “chlorophylls” was presented at 0.06 to 0.3ppm as the sum of four components, in which pheophytin a showed the highest content above 60%.

The role of essential fatty acids and prostaglandins.

The FAO/WHO Rome Report recommended an increase in the consumption of fat in countries where malnutrition is endemic; for maintenance, 3% of the dietary energy as essential fatty acids (EFA) may be adequate; in pregnancy and lactation an additional 1.5 to 2.4% energy as EFA is needed. For population at high risk for atherosclerosis and coronary heart disease (CHD) the recommendations were to decrease saturated fat in particular and increase EFA intake in the diet, reduce sugar, alcohol and cholesterol. These recommendations were similar to those of the Royal College of Physicians but the report went further by saying that EFA loss through industrial hydrogenation should be minimized and associated nutrients such as vitamin E and carotene should be restored if lost in processing. In terms of production, they asked for an increase in edible plant oils in developing countries and requested that intensive animal feeding and breeding should be corrected to avoid the excess accumulation of saturated fats. In addition, the Rome Report requested meaningful labelling of amounts and quality of fat in foods containing added fats. The basic aims of the Report were to state the position of lipid nutrition. The issue of the nutrient correction in terms of CHD cannot properly be discussed without taking into account the essential components which are needed for the integrity and development of the vascular system.