Roasting Does More than Enhance Flavor in Peanuts

December 9, 2009 By Rosalie Marion Bliss
Roasting Does More than Enhance Flavor in Peanuts
Dark roasting peanuts, peanut flour and peanut skins enhances their antioxidant levels, according to new ARS studies. Photo courtesy of Howard F. Schwartz, Colorado State University

( -- Agricultural Research Service (ARS) scientists have shown that increasing roast color intensity steadily ramps up the antioxidant capacities of peanuts, peanut flour and peanut skins.

The study was conducted by food technologist Jack P. Davis and his colleagues in the ARS Market Quality and Handling Research Unit in Raleigh, N.C. ARS is the principal intramural scientific research agency in the U.S. Department of Agriculture (USDA).

The researchers characterized changes in antioxidant levels of roasted peanuts and the corresponding blanched skins across an industrially relevant range of roast treatments. For the study, peanuts were incrementally roasted at 362 degrees Fahrenheit from zero to 77 minutes. The water- and oil-soluble antioxidant activity levels of the roasted peanut product samples were then determined.

Dark-roasting consistently increased water- and oil-soluble antioxidant capacities for both commercially available peanut flours and blanched peanuts. Peanut skins, currently considered a waste product of industrial peanut processing, had remarkably high antioxidant capacities across all roast conditions.

These antioxidant increases upon roasting were attributed to greater concentrations of phenolic compounds and/or "browning" reaction products. The latter result from thousands of complex in which proteins and sugars interact, ultimately resulting in brown pigmentation. These reactions, collectively termed Maillard browning, are also thought to contribute in part to the characteristic flavor of roasted peanuts.

The researchers also measured vitamin E in the roasted peanuts. Vitamin E degradation was most rapid in oil from lightly roasted peanuts; however, oil from darker roasted peanuts had better vitamin E retention than that of lightly roasted or even raw peanuts. This preservation of vitamin E could be due to the increased concentration of oil-soluble Maillard reaction products, which seem to protect vitamin E from oxidation.

While darker roasted peanuts are inappropriate for some applications due to sensory considerations, these materials are utilized to prepare, for example, darker roasted peanut flours and flavor extracts. The study expands the fundamental knowledge of roasting as it relates to the antioxidant capacity of peanuts and peanut ingredients, according to the authors. Davis reported the findings in Food Chemistry.

Provided by USDA Agricultural Research Service

Explore further: Boiled peanuts pack big antioxidant punch

Related Stories

Boiled peanuts pack big antioxidant punch

October 26, 2007

Boiled peanuts, a regional treat from the southern United States, may be as healthy as they are delicious. In the Oct. 31 issue of ACS' Journal of Agricultural and Food Chemistry, Alabama scientists report that boiling these ...

Salmonella: Tough to crack when it’s in peanuts

February 11, 2009

( -- For the second time in two years, a nationwide outbreak of salmonellosis has been tied to peanut products. This time, over 570 people have been sickened and over 1700 products have been taken off supermarket ...

Torrefacto-roasted coffee has higher antioxidant properties

March 6, 2008

Torrefacto-roasted coffee has higher antioxidant properties than natural roast, according to the dissertation defended by a biologist of the University of Navarra, Isabel López Galilea. She has emphasized in her study that ...

Peanut allergies overstated, study finds

May 16, 2007

Despite hundreds of families being told their children have peanut allergies every year, many of the children may be able to eat peanuts safely, a study by researchers at the University of New South Wales (UNSW) and Sydney ...

Peanut Allergies Showing Up At Much Earlier Ages

December 3, 2007

Children are being exposed to peanuts and exhibiting signs of life-threatening peanut allergies at much earlier ages, according to a new study from researchers at Duke University Medical Center, who caution parents and care-givers ...

Recommended for you

Efficient catalyst developed for producing pronucleotides

April 28, 2017

(—A team of researchers with Merck & Co., Inc. has developed an efficient catalyst for producing pronucleotides, paving the way perhaps to a new class of drugs for combatting viruses and cancer. In their paper ...

Tick protein helps antibiotics combat MRSA super bug

April 27, 2017

A protein derived from ticks enhances the effectiveness of antibiotic treatment for methicillin-resistant Staphylococcus aureus, or MRSA, according to a Yale-led study. The strategy of using the protein in combination with ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Dec 09, 2009
That's good to know. Now- is there similar increase in the same types of compounds in coffee beans related to degree of roasting?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.