Linolenic acid content

One of the interesting effects of ozone is the 56% increase in the linolenic acid content of ASG from ozonated bean leaves ( ), This led us to explore the source of the additional linolenic acid, Ongun and Mudd ( ) had reported that SG and ASG normally formed at the expense of free sterols in non-ozonated plants. What happens in ozonated plants ... 

In cereals the role of unsaturated fatty acids in cold acclimation has been demonstrated using a chemical (BASF 13-338) that reduces the linolenic acid content in polar lipids (St John et al., 1979). 

Borage Borago officinalis (Boraginaceae) seed 28-35 linoleic (38), y-linolenic (23-26), oleic (16), palmitic (11) dietary supplement for y-linolenic acid content (see page 46)... 

Klein, V., Chajes, V., and Germain, E. 2000. Low alpha-linolenic acid content of adipose breast tissue is associated with an increased risk of breast cancer. Eur. J. Cancer 36, 335. 

Substituted pyridazinones induce a specific decrease in the linolenic acid content accompanied by an increase in the linoleic acid content of plant membranes. The most distinct effect among many 5-substituted pyridazinones (78MI7 83M15 86MI21 87MI17) was shown by 4-chloro-5-... 

For mminant fat to become directly responsive to dietary unsaturated fats, it is necessary to protect the lipids against saturation by rumen microorganisms. The alteration of the lipid content of mutton by the feeding of such protected oil supplements has been described (14). Also, it has been shown that a diet of extruded soybeans increased the linoleic acid and linolenic acid contents of steer adipose tissue (15). 

Canola Oil Canola oil is obtained from low erucic acid, low glucosinolate rapeseed. The unique polyunsaturated fatty acid and low saturated composition of canola oil differentiates it from other oils. It has a higher oleic acid (18 1) content (55%) and lower linoleic acid (18 2) content (26%) than most other vegetable oils, but it contains 8-12% of linolenic acid (18 3) (58). Canola oil is most widely used in Canada and is considered a nutritionally balanced oil because of its favorable ratio of near 2 1 for linoleic to linolenic acid content. Unlike most other edible oils, the major breakdown products of canola oil are the cis, trans- and tram, trans-2,4-heptadienals with an odor character generally described as oily, fatty, and putty. Stored canola oil shows a sharp increase in the content of its degradation products, which are well above their odor detection thresholds. The aroma is dominated by cis, tram-, tram, frani-2,4-heptadienals, hexanal, nonanal, and the cis, trans- and... 

That a larger percentage of its linolenic acid content is in the sn-2 position in the triacylglycerols than is the case with soybean oil this confers somewhat greater resistance on linolenic acid to oxidation. 

According to the composition indicated by the Codex Alimentarius (Codex-Stan 210-1999), the saturated fatty acid content of regular sunflower oil is lower than that in corn (maximum 22%), cottonseed (maximum 32%), peanut (maximum 28%), and soybean (maximum 20%) oils, and higher than the saturated content of safflower (maximum 12%) and rapeseed (maximum 12%) oils. The linolenic acid content (18 3) of regular sunflower oil is fairly low (always lower than 0.3%), giving the oil a good oxidative stability. 

High-oleic sunflower oil, with very low PUFA levels, may well suit the requirements of processors, but it does not support the work of nutritionists who recommend n-6/n-3 ratios within the range 5 to 10. In addition, HOSO does not represent an increased intake of family n-3 fatty acids as recommended by nutritionists, the linolenic acid content being very low for all types of sunflower oil. 

TABLE 1. Linoleic and Linolenic Acid Contents of Some Vegetable Oils (104). 

Fatty Acid Composition The fatty acid content of RBO is mainly palmitic, oleic, and linoleic acid (Table 24). The low linolenic acid content of RBO makes it stable to oxidation. Several studies reported variations in fatty acid composition of RBO (90, 95-96). Goffman et al. (90) studied the fatty acid composition of 204 rice varieties. Genotype and environment significantly affected stearic, oleic, linoleic, and linolenic acids but not palmitic acid content of the RBO. The ratio of saturated to unsaturated acid ratio (S/U) was correlated to the palmitic acid content of the oil. Japonica lines had low palmitic acid content and S/U ratio, whereas Indica lines were characterized by high palmitic acid content and high S/U ratio (90). 

Several studies have confirmed that the seed oil from the North American variety of cranberry contains significant levels of a-linolenic acid. In a U.S. patent, Heeg et al. (4) reported the a-linolenic acid content of cranberry seed oil to be between 30% and 35% of total fatty acids. In 2003, Parker et al. (5) found 22.3% a-linolenic acid in the cold-pressed cranberry seed oil, and in 2004, Parry et al. (3) determined the oil to contain 32.0% a-linolenic acid from two different lots of the seed oil. The ratios of n-6 to n-3 fatty acids in all were low from 1.2 1 to 2 1. Also, all of the studies documented similar ratios among the rest of the common fatty acids found in cranberry seed oil, including, in order of higher amount present linoleic, oleic, palmitic, stearic, and eicosadienoic (20 2) acids (Table 1). In addition to a-linolenic acid, cranberry seed oil is rich in natural antioxidants (8). These antioxidants may directly react with free radicals and prevent lipid oxidation in human low-density lipoprotein. 

Linolenic acid content must be low in order to provide maximum oxidative stability to the oil. This is why soybean and canola oil, which contain about 8% linolenic acid in the natural state, are hydrogenated to reduce their linolenic acid content to less than 2% determined by the capillary GC Method (2). Poor frying stability in sunflower oil comes primarily from the high level of hnoleic acid. Therefore, sunflower oil must also be hydrogenated to reduce its linoleic acid content to 35% or lower for industrial frying. Table 1 lists the analyses of the most commonly used industrial frying oils. 

Table 4 shows that hydrogenation of soybean oil to a linolenic acid content of less than 2% increased the AOM value from 15 hours to over 30 hours. Simlarly, the AOM value rose from 20 hours to over 75 hours for canola oil after hydrogenation. However, hydrogenation also produced significant levels of tran -fats in both oils (2). 

Reported activation energy values for the thermal i-rra i-isomerization of linoleic and linolenic acid are rather low (178 kJ/mole vs. 144—148 kJ/mole, respectively) (8). This is an indication that TFAs are relatively easily formed at elevated deodorization temperature. Different studies show that the relative isomerization rate can be expressed as follows Cig 3 (100) Cig 2 (10) Cig i (1) (11-13). Consequently, oils with a high linolenic acid content, such as soybean and rapeseed oils, are most sensitive to di-fra i-isomerization during deodorization. 

The genetically altered oils, 3% linolenic acid, and now 1% linolenic acid soybean oil, may become popular as zero trans-frying fats, as the size of the crop for these seeds advances. These oils would be zero trans- and no hydrogenation. As touted by the Better Bean Initiative, the 3% linolenic variety could become the mainstream variety, requiring no identity preservation. (Note If 3% linolenic acid soybean oil is lightly hydrogenated, less trans-would be produced because of the lower initial linolenic acid content). 

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