Phytosterols are bioactive compounds, one of their most studied and outstanding properties being their cholesterol-lowering activity. This explains the growing interest in the phytosterol contents of foods as either intrinsic or added components. The different steps (extraction, saponification, clean up, chromatographic determination) of plant sterol determination are reviewed, and emphasis is placed on the methods used to assay different phytosterols in food.

No abstract

No abstract

The minimal refining method described in the present study made it possible to neutralize crude canola oil with Ca(OH) 2 , MgO, and Na 2 SiO 3 as alternatives to NaOH. After citric acid degumming, about 98 % of the phosphorous content was removed from crude oil. The free fatty acid content after minimal neutralization with Ca(OH) 2 decreased from 0.50 to 0.03 %. Other quality parameters, such as peroxide value, anisidine value, and chlorophyll content, after traditional and minimal neutralization were within industrial acceptable levels. The use of Trisyl silica and Magnesol R60 made it feasible to remove the hot-water washing step and decreased the amount of residual soap to \10 mg/kg oil. There were no significant changes in chemical characteristics of canola oil after using wet and dry bleaching methods. During traditional neutralization, the total tocopherol loss was 19.6 %, while minimal refining with Ca(OH) 2 , MgO, and Na 2 SiO 3 resulted in 7.0, 2.6, and 0.9 % reductions in total tocopherols. Traditional refining removed 23.6 % of total free sterols, while after minimal refining free sterols content did not change. Both traditional and minimal refining resulted in almost complete removal of polyphenols from canola oil. Total phytosterols and tocopherols in two cold-pressed canola oils were 774 and 836 mg/100 g, and 366 and 354 mg/kg, respectively. The minimal refining method described in the present study was a new practical approach to remove undesirable components from crude canola oil meeting commercial refining standards while preserving more healthy minor components.

In this study the quality characteristics and content of healthy minor components of four crude canola oils as an effect of different oil extraction method (solvent extraction, hot pressing, and cold pressing) were studied. Cold-pressed canola oils had lower concentrations of FFA, PV, p-AV and chlorophylls than solvent-extracted, and hot-pressed canola oils. Oils obtained via the different extraction methods had different fatty acid profiles as well as dissimilar amounts of tocopherols, phytosterols, and polyphenols. The amount of total tocopherols in solvent-extracted canola oil was 493 mg/kg compared to 388 mg/kg for hot-pressed canola oil. The tocopherol content for two other cold-pressed and one other RBD canola oil was 366, 354, and 327 mg/kg, respectively. Solvent-extracted canola oil exhibited the highest free phytosterol content (178 mg/100 g), while RBD canola oil only had 129 mg/100 g of free phytosterols. While cold-pressed canola oil had the lowest amount of polyphenols, traditional refining resulted in almost complete removal of polyphenols from canola oil.