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United States Department of Agriculture

Agricultural Research Service

Chemistry
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Beneficial Uses of Peanut By-products


Peanuts.
The most attractive heart-healthy, anti-aging, and anti-cancer compound in peanut kernels is resveratrol, which is also found in red grapes and red wine.

Foods containing resveratrol

What do they have in common?

Resveratrol content in commercial peanuts and peanut products was investigated for the first time on a large scale. Resveratrol content in roasted peanuts was 0.02 - 0.08 µg/g and in peanut butter 0.15- 0.50 µg/g. Boiled peanuts showed the highest concentrations from 1.80 to 7.87, which are comparable with resveratrol concentrations in red wines.

Peanut Skins. Peanut skins are an extremely low value by-product of peanut-blanching operations. Based on current world in-shell peanut production of peanuts, world production of peanut skins can be estimated at about 1 million tons annually. Research performed at the NPRL to find new uses for peanut skins demonstrated that up to 35% of edible oil in the skins can be recovered. After removal of the oil the skins were useful for making brandy, liquor, and tea. Skin oil extraction followed by tannin extraction also produced a protein-enriched product that could find applications in mixed feeds for cattle consumption at higher concentrations relative to existing practice. A simple technique was also offered to use the skins in finishing decorative panels.

The use of peanut skins is summarized in the following chart.

Chart depicting the various uses of peanut skins

 

For more information contact Victor Sobolev.

 


Low Cost Aflatoxin Analysis


Can we reduce the high safety/analytical cost without compromising reliability, and accuracy?

Yes, by developing practical methods for mycotoxin analyses in peanuts and other commodities for the industry and research institutions.

New methods are in great demand due to high cost and complexity of the existing methods. Development and implementation of simple inexpensive methods allow for significant savings for industry and research institutions.

  Consumables required for clean-up procedure

 Commercially available aflatoxin analysis kit

Shown are the consumables required for the cleanup of aflatoxins in agricultural commodities. The cost of the consumables does not exceed $1/analysis, which is a substantial saving compared with commercial cleanup devices that cost $8-12/analysis. Shown is a commercial product designed at the NPRL for aflatoxin analysis.

Several methods for determination of other mycotoxins, as well as peanut phytoalexins, were also developed at the NPRL.

For more information contact Victor Sobolev.

 


Natural Peanut Resistence to Pests


Do we know everything that we should know about peanut physiology?

No, particularly not enough is known about peanut natural defensive mechanisms against pests.

Phytoalexins. Peanuts can naturally fight diseases by producing antibiotic compounds (stilbene phytoalexins). However, the exact mechanism of peanut resistance to fungal invasion is not understood. A greater understanding of peanut resistance to pests can lead to new beneficial agricultural practices. Manipulation of host plant resistance is an efficient, economical and environment-friendly approach used to manage many pests and diseases of agricultural crops. In addition, stilbene phytoalexins may be considered potential chemical markers in breeding programs for disease-resistant peanuts.

Peanut kernel infected by fungus showing phytoalexin production

A dissected peanut kernel infected by a soil fungus (Aspergillus niger). Yellow-colored  phytoalexin is locally produced by the kernel tissues (arrow). The phytoalexin (termed SB-1, the structure is shown) was first discovered at the NPRL.

 Photomicrograph of peanut root tip
Photomicrograph of peanut root tip showing the yellow mucilage layer. Seven new hydrophobic prenylated stilbenoids, including mucilagin A, were isolated from the mucilage for the first time; their structures were elucidated. These compounds were restricted to mucilage, which suggests their special role in regulating root-soil pathogen interactions.

Interrelationship of stilbene phytoalexin production and resistance of several peanut genotypes to major peanut diseases, including TSWV was also demonstrated for the first time.

 Interrelationship of phytoalexin production and peanut resistance to major diseases

Ability of peanut genotype to synthesize stilbene phytoalexins

Table showing interrelationship of phytoalexin production and peanut resistance to major diseases.

Susceptability of peanut genotypes to major diseases including: TSWV*, WM*, and LLS*.

 * TSWV, tomato spotted wilt virus; WM, White Mold; LLS, Late Leafspot

 

Flavonoids and spermidines. Sound seed yield depends heavily on high peanut resistance to pests and uncompromised plant fertility. Peanut flowers have been considered resistant to pests. Compounds that may be responsible for such resistance have not been investigated.


The study revealed the production of flavonoid and spermidine conjugates in the peanut flower at high levels. All major metabolites have been detected in the flowers for the first time. One of the metabolites, acetyldicoumaroylspermidine (structure is shown below), has not been previously reported in plants. Both flavonoid and spermidine conjugates may play a protective role against pests as it has been shown for similar compounds in other plants. The new spermidine conjugate may be involved in regulating the plant reproduction process.

Peanut flower

Chemical structure of a new spermidine derivative.

Shown are the  peanut flower and the structure of a new spermidine derivative. 1 – standard; 2 – one of two symmetrical wings (one of the wings is removed for a better observation of the keel); 3 – keel (2 fused petals that enclose pistil and stamens); 4 – hypanthium.

Spermidine compounds, similar to the one above, have been reported to appreciably inhibit HIV-1 protease that is essential for the life-cycle of HIV. One of the compounds also demonstrated high activity against Helicobacter pylori, a major etiological agent in gastroduodenal disorders. Study of biological activity of the new peanut spermidine derivative is anticipated.

 

For more information contact Victor Sobolev.

 


Last Modified: 1/22/2009