Beany odor

Volatile aldehydes, including 1-hexanal, may be primarily responsible for the beany odor of soybean (10, 13, 14). They are present even in defatted soybean flour. Recently, Chiba et al. (15) have deodorized soybean flour by treatment with aldehyde dehydrogenase from bovine liver. Deodorization was a result of converting aldehydes to acids, e.g., 1-hexanal to caproic acid. They postulated that both free and bound aldehydes can act as substrates for this dehydrogenase. Consequently, enzymatic treatment resulted in a product without beany odor. 

Pentyl furan, which has been was identified in com oil is a volatile compound obtained from the oxidation of the com oil. The flavor threshold of this compound in oil, at room temperature, is 1 ppm. At concentrations of 1-10 ppm, it imparts, the oil a characteristic beany odor (Krishnamurthy et al., 1967 Steenson et al., 2002)... 

The oil after heating shall be bland and free from beany, rancid, painty, musty, soapy, fishy, metallic, and other undesirable or foreign flavors and odors when tested by the method prescribed in footnote m within 7 days after packaging each lot. 

It has a powerful and penetrating smokey-tarry odor, in extreme dilution sweet, woody-herbaceous, slightly animal (Arctander, 1967). It has a green, beany, metallic flavor (Chemisis, 1997). 

Partial proteolysis of soybean proteins with endopeptidases has been used to remove flavor compounds and related fatty materials from soybean curd and defatted soybean flour (21). Certain soybean protein concentrates possess an undesirable beany and oxidized flavor. Treatment of soybean curd and defatted soybean flour with endopeptidases such as aspergillopeptidase A released off-flavor compounds such as 1-hexanal and 1-hexanol which could be removed from the hydrolysate by solvent extraction. The enzymically digested products had less odor, taste, and color than the starting material and were more stable to oxidative deterioration. 

The U.S. Department of Agriculture (USDA) quality standards for soybean oil state that soybean oil shall be clear and brilliant when held at 70-85°F and shall be free from sediment, such as metal, wood, dirt, glass, paint, insects, insect parts, or any other foreign material (Anonymous, 2005). In addition, the oil shall have a bland odor and flavor and shall be free of beany, rancid, painty, musty, metallic, fishy, putrid, or any orher undesirable odor and/or flavor and have a light viscosity and no heavy oily mouthfeel. Table 15.4 lists the analytical requirements for a RBD and... 

Properties Colorless to yel. liq. fruity green earthy beany vegetable metallic odor m.w. 138.21 sp.gr. 0.886 dens. 7.372 Ib/gal b.p. 64-66 C (23 mm Hg) flash pt. 45.55 C ref. index 1.447 (20 C) Toxicology LD50 (oral, mouse) 1200 mg/kg may be harmful by inh., ing., skin absorp. may cause irritation TSCA listed Precaution Combustible incompat. with strong oxidizing agents... 

Ethanol has also been utilized for oil extraction. Oil solubility in ethanol varies with temperature and water content. Soybean oil is completely miscible with absolute ethanol above 70 °C (Johnson and Lusas, 1983). As ethanol concentration decreases and water content increases, oil solubility is significantly reduced in the mixture. The higher cost and latent heat of vaporization are the major disadvantages of ethanol as a solvent for oilseed extraction. Recent developments in bioethanol production may reduce the cost of ethanol, making it a viable alternative to hexane. Solvent mixtures can also be used to extract oil. Hexane/alcohol azeotropes have been used for extraction of residual lipids from hexane-extracted meals to improve flavor and odor, specifically from soybean and peanuts. Grassy and beany flavors in oilseeds are associated with the presence of phosphatides, which can be easily extracted with hexane/alcohol mixtures. Similarly, hexane/alcohol azeotropes, specifically hexane/methanol, are very effective in extracting aflatoxin from meal. 

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