Rapeseed plant selection

Rapeseed oil has been used for a number of years in food applications as a cheap alternative to olive oil. However, there are large amounts of etude acid and glucosinolates in conventional rapeseed oil, both substances being toxic to humans and animals. Canola oil derived from genetically selected rapeseed plants that are low in erucic acid content has been developed to overcome this problem. 

The vapor stream from the meal and oil distillation systems consists of solvent vapor, water vapor (from the stripping steam) and air that has entered the system entrained in the voids of the press cake. Some additional air unavoidably gains entry into the vacuum systems. The vapor stream from the final condenser consists of air saturated with solvent and water vapors. The solvent vapors are selectively scrubbed in a packed tower by a counterflow of special mineral oil. The mineral oil is recycled after being heated, stripped of solvent, and cooled. The hexane vapor remaining in the vent stream should be below the lower explosive limit (1.3% by volume). Nevertheless, overall rapeseed plant losses per tonne flow through the extractor are typically much higher than they are for soybeans. This problem should be researched and, if possible, overcome. 

Since the late 1960s to the present date, plant breeders have diligently selected rapeseed to minimize or eliminate the erucic acid from the oil and glucosinolates from the meal. Much of the recent expansion in the rapeseed industry in Canada and Europe is attributable to the dramatic improvements in the quality of oil and meal over the past 20 years. Another important factor is the wide adaptability of different types of rapeseed to different environments and their ability to thrive in harsh climates. In Canada and Europe most rapeseed is grown north of the 45° parallel. However, in China and India production is comparatively close to the equator, approximately 25°-40°N. This combination of improved quality and wide adaptability makes the crop very attractive to many developed and developing countries which are otherwise deficient in edible oil and in high protein meal. 

In the same year the Food and Drug Directorate modified the restrictions on the use of rapeseed oil pending a submission showing the safety of HEAR oil for human use. A review of the published information on the nutritional properties of rapeseed oil presented in 1956 led the Canadian Committee on Fats and Oil to conclude there was no evidence to indicate that limited use of HEAR oil constituted a human health hazard. However, the committee indicated the need for further information on the nutritional properties of HEAR oil. It was also decided that research should be initiated to determine if the erucic acid content of HEAR oil could be lowered by selective plant breeding. Erucic acid in HEAR oil was further implicated as a component of concern in 1957 by Carroll and Nobel who suggested that erucic acid affected the reproduction of rats. 

The commercial exploitation of sperm oil has led to the depletion of whale populations and is banned in some countries. Attention has, therefore, turned to the jojoba plant whose oil also consists of wax esters. Most fatty chemicals obtained from natural sources have chain lengths of Cig-Cig. The limited availability of compounds with 12-14 carbon atoms, which are important in surfactants, was one of the driving forces behind the development of petrochemical processes for the production of fatty alcohols. Higher alcohols, such as C20-C22 alcohols, can be produced from rapeseed oils rich in erucic acid and fish oils. Unsaturated fatty alcohols may be manufactured in the presence of selective catalysts. 

These hypotheses were examined by characterizing the selectivity of CPT and DAGAT in microsomal preparations from developing cotyledons of a series of oilseed plants towards different DAG species. Four different plants were used as model systems safflower (Carthamus tinctorius), a plant producing no unusual fatty acids rapeseed (Brassica napus), which stores erucic acid (22 1) in its TAG species Cuphea, a plant accumulating medium chain fatty acids (C8 - C12) in its seed triacylglycerols and castor bean (Ricinus communis) which stores up to 90% ricinoleic acid (18 1-OH) in its seed oils. 

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