Soybeans antioxidant properties

The food technologist may be especially interested in the fate of the carotenoids in the seed oil. Like red palm oil, the resulting carotenoid-pigmented canola oil may be more stable due to the antioxidant properties of carotenoids and may be more attractive to consumers. Alternatively, for food security concerns, transgenic soybean or canola oils and seed meals that are genetically modified for more efficient bio-diesel production may be bio-safety marked with lipid-soluble carotenoids and water-soluble anthocyanins, respectively. Potatoes are excellent potential sources of dietary carotenoids, and over-expression of CrtB in tubers led to the accumulation of P-carotene. Potatoes normally have low levels of leaf-type carotenoids, like canola cotyledons. 

Chen, H., Muramoto, K., Yamauchi, F., Fujimoto, K., and Nokihara, K. (1998). Antioxidative properties of histidine-containing peptides designed from peptide fragments found in the digests of a soybean protein. ]. Agric. Food Chem. 46,49-53. 

The value of antioxidant protection by way of natural food sources has been pointed out in the literature with considerable frequency. Among the components of soy flour known to have some antioxidant properties are isoflavones and phospholipids. Amino acids and peptides in soybean flour also possess some antioxidant activity. There also may be some antioxidant impact from aromatic amines and sulfhydryl compounds. 

Shimada, K., Fujikawa, K., Yahara, K., and Nakamura, T. 1992. Antioxidative properties of xanthan on the autoxidation of soybean oil in cyclodextrin emulsion. J. Agric. Food Chem. 40 945-948. 

The quality changes, such as lipid oxidation and reduction of tocopherols and phytosteols during neutralization, are considerable compared with the other processing steps as shown by Wang and Johnson (174), and also as presented in Table 12. The further phospholipid removal (below 2 ppm phosphorus) also reduces the oxidative stability of soybean oil (175) due to the antioxidant property of these phospholipids. 

Lecithins as antioxidants. The literature is replete with references to the antioxidant properties of lecithins. For example, Pokomy (102) claimed that the addition of soybean phospholipids reduced the rate of autoxidation of sunflower oil and prolonged the induction period. Hudson and Ghavani (103) published data showing that the addition of 0.3% dipalmitoyl phosphatidylethanolamine (DPE) to refined soybean oil increased the induction time during Rancimat analysis from 8.8 hours to 19.3 hours. Hildebrand et al. (104), and Jung et al. (105), also published data demonstrating the antioxidant properties of various phospholipids and commercial lecithins. 

The formulator needs to know the properties of each antioxidant. For example, most of the antioxidants are easily distilled by heat or steam. Propyl gallate will form strong purple complexes with iron. The preservative effects of antioxidants also can be enhanced by addition of metal chelating agents like citric acid. Furthermore, many crude feedstuffs of plant origin, including soybean meal, crude soybean oil, and lecithin, contain a variety of natural quinone-type compounds with beneficial antioxidant properties that do not require labeling. 

Morgan, J.F. Klucas, R.V. Grayer, R.J. Abian, J. Becana, M. Complexes of iron with phenolic compounds from soybean nodules and other legume tissues prooxidant and antioxidant properties. Free Radical Biol. Med. 1997, 22, 861-870. 

Fleury, Y., Welti, D.H., Philippossian, G., and Magnolato, D. 1992. Soybean (malonyl) isoflavones characterization and antioxidant properties. ACS Symp. Ser. 507 98-113. 

Lee, K.G. and Shibamoto, T., Antioxidant properties of aroma compounds isolated from soybeans and mung beans, J. Agric. Food Chem., 48, 4290, 2000. 

Tocopherols exhibit antioxidant properties and contribute significantly to the oxidative stability of oils (Sherwin, 1976). Typical tocopherol concentrations for crude soybean oils, representing 14 lines of soybeans exhibiting conventional FA compositions grown in the Midwest, are reported in Table 7.3 (Dolde et al., 1999). Others have reported ratios of approximately 1 13 5 for a-, y-, and 5-tocopherols in soybean oils (Jung et al., 1989 Evans et al., 2002). In general, tocotrienols were not detected in soybeans (Ko et al., 2003). 

Significant amounts of sterols are lost during oil heating at frying temperatures (Ghavami Morton, 1984). However, the antioxidant properties of A7-avenasterol, a minor sterol in soybean oil, were reported at frying temperatures (Sims et ah, 1972 Yan White, 1990). 

Fermentation of soybean has also yielded peptides with antioxidant properties in two soy-fermented products, natto and tempeh (Wang et al., 2008). Also, natto fermented by B. subtilis has been shown to exhibit radical scavenging activity and inhibitory effect on the oxidation of rat plasma LDL in vitro (Iwai, Nakaya, Kawasaki, Matsue, 2002). A low-molecular-weight viscous substance (molecular weight < 100 kilo Daltons) had... 

Pyo, Y.H., Lee, T.C., and Lee, Y.C. 2006. Effect of Lactic Acid Fermentation on Enrichment of Antioxidant Properties and Bioactive Isoflavones in Soybean. Journal of Food Science, 70(3), S215-S220. 

Peptides with antioxidant properties are effective against enzymatic and non-enzymatic oxidation of lipids, as free radical scavengers and in metal ion chelations. An example is a soybean pentapeptide with the sequence Leu-Leu-Pro-His-His. 

To expand commercialization of soybean-oil-based lubricants, one of three factors must occur to eliminate cost as a deterrent (i) the increased cost of the product must provide increased performance (ii) the cost of competing petroleum products must increase significantly or (iii) the use of the biobased product must provide the best way to meet required local, state, or federal regulations. Of these three factors, the first, improving the properties of soybean oil, is the most desirable scenario. Improve the low-temperature properties of soybean oil by blending with diluents, such as poly-alphaolefins, diisodecyl adipate, and oleates (Asadauskas Erhan, 1999 Erhan et al., 2006) improve oxidative stability by adding commercially available antioxidants (Becker Knorr, 1996 Erhan et al., 2006 Sharma et al., 2007b). 

In 1985, ANPA came out with the first-generation soybean-oil-based lithographic news ink, comprised of alkali-refined soybean oil, hydrocarbon resin, carbon black pigment, and an antioxidant (Moynihan, 1985a). This black ink had similar printing properties to mineral-oil-based inks, but cost 30—50% more. The color inks were formulated in a similar way, had good print quality, but cost about 5—10% more than the petroleum-based commercial inks. Thus, industry continued to search for 100% vegetable-oil-based inks to replace petroleum-based inks. 

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