Peanut nutty flavor

A process has been developed (139) whereby up to 80% of the oil can be removed from whole, raw peanuts without the use of solvent. In this process, the blanched peanuts are brought to a proper moisture content, pressed mechanically, and then reshaped or reconstituted by dipping in hot water subsequently they can be roasted and salted, or used in confections or other formulations. Defatted peanuts may also be ground into meal and added to cookies, cakes, and many other products, where they impart a distinctly nutty flavor and cmnchy texture. On the other hand, the resulting high grade oil is refined and employed in cooking and industrial products. This process can also be used for pecans, walnuts, almonds, Brazil nuts, cashews, and other nuts (140-142). 

Defatted peanuts are high in protein, low in moisture, contain only 20% of the naturally occurring fat, and have better stability than whole peanuts. Monosodium glutamate (MSG) has been used as a flavor enhancer for defatted nuts, but the result has not been entirely satisfactory as the addition of MSG produces a meaty rather than nutty flavor. This meaty flavor is more compatible with salted butter and nuts than with candy. 

A typical specification for finished rice bran oil is shown in Table 13. These are similar to that for other oils. Rice bran oil has a characteristic nutty, earthly flavor not unhke peanut oil. 

Peak 24 was identified as 2-ethyl-6-methyl pyrazine. This was a typical pyrazine which had been identified in peanuts. Organoleptically this compound represented roasted, nutty, earthy notes. The positive correlation of +0.98129 (C.D.) showed that sensory preference increased with concentration. These plots indicated that a decrease in carbonyls with a subsequent increase in pyrazines were important to good quality peanut flavor. This supported the work of Mason et al (13, and Johnson 2, 6). 

The roasting process subjects peanuts to internal temperatures of 130 -150 C during which the typical roast peanut flavor is produced. The most important constituents of peanuts responsible for flavor formation are the amino acids, sugars, protein and lipids. There are close to 300 flavor compounds identified in roasted peanuts. Pyrazines contribute roasted nutty aroma and aldehydes are responsible for harsh green aroma. Recent development in the research include application of an absorption polymer Tenax GC to collect volatiles, quantitation of flavor components and computer aided correlation of instrmental and sensory data. 

Pyrazines are the noajor compound classes in peanuts, formed through the thermally induced MaiUard reaction (with the exception of methoxy pyrazines) (61). Two pyrazines that represent peanut flavor character are 2,5-dimethylpyrazine (nutty) and 2-methoxy-5-methylpyrazine (roasted nutty) (Table 5). 

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