The Powers of Peanut Flours
By Rosalie Marion
January 25, 2007
New Agricultural Research Service
(ARS) findings about the thickening
capacity of various forms of peanut flour will help scientists improve food
Peanut flour is a dry powder formed after the partial extraction of oil from
the roasted peanut seed. It is used to add flavor and protein to processed
baked goods, nutrition bars and snacks, as well as to marinades, sauces and
dressings. Worldwide, peanut flours have been limited to use by industrial food
processors as a major food ingredient.
The study was conducted by food technologist
P. Davis and colleagues in the ARS
Quality and Handling Research Unit, Raleigh, N.C. ARS is the
U.S. Department of Agriculture's chief
scientific research agency.
To gauge how effectively different commercial peanut flours thicken during
heat processing, Davis used different types of rheological tests. Rheological
measurements involve testing the flow behavior and form changes of a material
and have been shown to relate to the human perception of texture.
Generally, peanut flours are offered at fat levels of 12 or 28 percent, and
either as light, medium or dark roasts. Davis found that regardless of roast
color, lower-fat peanut flours thicken more effectively than higher-fat ones.
While peanuts are about 25 percent protein, peanut flour is about 50 percent
protein. That's because the process of mechanically removing fatty oil from
roasted peanuts enriches the levels of the remaining peanut components. The
resulting flour is naturally low in fat, high in protein and relatively low in
Ounce-per-ounce, low-fat, light-roasted peanut flours were found to promote
more viscosityor to thicken more effectivelythan other peanut
flours when dispersed in water and heated under controlled conditions.
Davis and ARS research leader
Sanders will report the findings in an upcoming issue of The Journal
of Texture Studies. That data and those from future studies will help
food processors choose the best heat treatments, based on a particular peanut
flour's thickening properties.