Oils with Modified Fatty-Acid Content

3 Oils With Modified Fatty-Acid Content 

To exploit additional market opportunities or to improve oil characteristics, traditional plant breeding methods have been used to create oils with modified fatty acid profiles. 

---

A major issue for biomass as a raw material for industrial product manufacture is variability. Questions of standardisation and specifications will therefore need to be addressed as new biofuels, biomaterials and bioproducts are introduced onto the market. Another major challenge associated with the use of biomass is yield. One approach to improve/modify the properties and/or yield of biomass is to use selective breeding and genetic engineering to develop plant strains that produce greater amounts of desirable feedstocks, chemicals or even compounds that the plant does not naturally produce (Fernando et al., 2006). This essentially transfers part of the biorefining to the plant (see Chapter 2 for some example of oils with modified fatty acid content). 

Recently, novel dietary oils with modified fatty acid profiles have been manufactured to improve fatty acid intakes and reduce CVD risk. Our objective was to evaluate the efficacy of novel high-oleic rapeseed (canola) oil (HOCO), alone or blended with flaxseed oil (FXCO), on circulating lipids and inflammatory biomarkers v. a typical Western diet (WD). Using a randomized, controlled, crossover trial, thirty-six hypercholesterolaemic subjects consumed three isoenergetic diets for 28 d each containing approximately 36% energy from fat, of which 70% was provided by HOCO, FXCO or WD. Dietary fat content of SFA, MUFA, PUFA n-6 and n-3 was 6, 23, 5,... 

Justin Stege (Diversa Corporation) discussed the molecular evolution of enzymes for particular pathways, with a focus on the modification of oil composition. Oleochemical applications for such enzymes include applications as biocatalysts for fatty acid modifications. In a program to integrate production and processing, such enzymes can be used to modify the fatty acid content of vegetable oils in planta. Results show that expressing such new enzymes in oilseed crops has resulted in altered oil composition, and that the features may be used to better design plant-based oils for use as biofuels and as improved renewable feedstocks. 

As indicated previously in this chapter, regular soybean salad oil, if processed and stored properly, has very good oxidative stability as a salad oil. In some instances, however, extra oxidative stability may be needed. In those cases, soybean oil with a modified fatty acid profile may be appropriate, such as one with reduced linolenic acid. Several studies on soybean oil modified to reduce the linolenate content showed that this approach improved the flavor quality and oxidative stability of the soybean salad oils (Mounts et d., 1988 Liu ite, 1992a Mounts et al., 1994a Su et al., 2003). Decreasing the linolenic acid helps to inhibit oxidation and the development of painty flavors derived from the oxidation of linolenic acid. 

Crude soybean oil can be obtained from the bean by pressing but more normally by hexane extraction. Good-quality oil is light amber in colour with a free fatty acid content of 0.5%. Oil from damaged beans is darker, higher in free fatty acids and modified lipids and is more difficult to bleach. The residual meal is a major source of animal feed. 

In canola, the most important fatty acids are oleic acid (C18 l), a-linolenic acid (ALA, C18 3), erucic acid and the sum of the total saturated fatty acids. Canola is often referred as a double low rapeseed, low in total glucosinolate—<30 pmol/g oil-free solid dry basis, and low erucic acid—<2% (http //canolacouncil.org/canola the offlcial deflnition.aspx). To ensure that the seeds conform to the definition of canola, it is important to analyse the erucic acid content. Nowadays monthly monitoring of Canadian canola exports showed that erucic acid content is weU below the 2% mark, in fact, the erucic acid content average was below 0.15%. Canola oil has been modified in response to industry demand for an oil that allows deep-frying. It was necessary to develop an oil more stable to oxidation, to allow the high deep-frying temperatures. Low a-linolenic acid canola (LowLin) was developed. The new varieties could be grouped into low a-linolenic acid (below 5%) with an oleic acid content of around 65%, or into very low a-linolenic add (below 3%) with a content... 

Fats and oils are triesters of the trivalent alcohol glycerol and three (different) even-numbered aliphatic carboxylic acids, the fatty acids. Fats and oils differ in the length and the number of unsaturated bonds in the carbon chain. The shorter Cio-Ci4-fatty acids are obtained from coconut oil and palm kernel oil. These fatty acids are mostly saturated, and they are used in the manufacture of detergents. Cig-fatty acids are more widely used. Oleic acid, a Cig-fatty acid with an unsaturated bond on the ninth carbon atom, can be produced from many crops. Specific varieties or genetically modified plants, such as rape, have a content of over 90% oleic acid [4]. 

The earliest efforts to modify the composition of milk fat used an insoluble formaldehyde-crosslinked protein to encapsulate unsaturated vegetable oils. In numerous studies using this approach, linoleic acid was increased to as high as 35%, w/w, of the total milk fatty acids (reviewed by McDonald and Scott, 1977). Bitman et al. (1973) fed increasing amounts of safflower oil encapsulated in formaldehyde-treated casein. The content of milk fat increased linearly from 3.5 to 4.6% as supplemental protected oil was increased from 0 to 1320 g/day per cow. The concentration of linoleic acid increased to 33% of total milk fatty acids, with a compensating decrease in Ci6 o and a smaller decrease in Ci4 0. The concentration of milk fat decreased to lower than pretreatment levels when the supplement was removed, a common observation (Pan et al., 1972). A typical milk fatty acid profile from cows fed a protected sunflower/soybean (70/30) supplement is shown in Table 2.1. 

Another aspect of heating soybeans in particular is the impact on the phospholipase enzyme. The phospholipase enzyme is activated at approximately 55°C and remains activated up to approximately 100°C. In this temperature range, and with sufficient exposed surface area and time, the phospholipase enzyme modifies a portion of the phospatides in the oil fraction by splitting off the non-fatty acid moiety (16). The resultant calcium and magnesium salts of phosphatidic acids that are formed tend to be more oil-soluble than water-soluble, thereby converting phospatides from a hydratable form to a nonhydratable form (16). This has a resultant impact on the quantities of acid, caustic and silica needed to reduce the phosphorus content of the soybean oil in the downstream degumming and refining unit operations. 

---