Roasting Does More than Enhance Flavor in Peanuts

Dec 09, 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: Method keeps salmon fresh for a month without the use of chemicals

Related Stories

Boiled peanuts pack big antioxidant punch

Oct 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 ...

Salmonella: Tough to crack when it’s in peanuts

Feb 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

Mar 06, 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

Dec 03, 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

Video: The chemistry of grilling

Jun 29, 2015

If you're firing up the barbecue this week for an Independence Day cookout, you don't want to miss this week's Reactions video.

Researchers scientifically characterize Finnish sahti beer

Jun 23, 2015

A group of experts from VTT Technical Research Centre of Finland considered that it's high time to finally scientifically characterize sahti beer. The sweet and strong sahti with its exceptionally rich combination ...

Feds paying for sewer analysis of pot usage in Washington

Jun 23, 2015

The federal government is chipping in money for a three-year pilot study using sewage samples to determine levels of marijuana use in two Washington cities—research that could help answer some key questions ...

User comments : 1

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.