Value-Added
Use for Peanut Skins
Key Facts
• Peanut skins
are a processing waste product.
• Peanut skins are rich in plant
compounds called polyphenols.
• ARS scientists made a food ingredient
from peanut skins.
• The ingredient increased polyphenol
levels in milk chocolate without affecting flavor.
An
ARS-developed peanut skin extract can increase
milk chocolate's polyphenol level without
affecting flavor. (Peggy Greb, D3715-1)
Dark chocolate is touted for its higher levels of plant-based cocoa
bean than milk chocolate, but that does not mean chocolate lovers enjoy
milk chocolate any less. Love of milk chocolate is mostly about the
yummy taste from added fats, sugars, and creams versus dark chocolate's
higher levels of defatted cocoa powder known as cacao.
Now, ARS researchers in Raleigh, North Carolina, have reported that
consumers can enjoy the taste of milk chocolate that contains similar
levels of plant compounds known as "polyphenols" as found in dark
chocolate.
For the new study, ARS researchers increased the levels of phenolic
compound in milk chocolate to levels equivalent to those of dark
chocolate without negatively affecting the flavor. They achieved the
boost by adding an ingredient extracted from something usually
considered as waste-peanut skins.
Plants protect themselves against stressors by forming chemical
compounds that include polyphenols. Both cocoa and peanut skins are
rich in polyphenols—although it is unknown at this time if polyphenols
from peanut skins and cocoa are equally bioaccessible (meaning in
ability to release from food) or equally bioavailable (meaning for use
by a consumer).
Peanut processing removes thousands of tons of peanut skins each year,
which are generally considered little more than a waste-management
problem. The ARS scientists developed a process to turn peanut-skin
extract into a powder that can be used as a food ingredient. Food
technologist Lisa Dean, with the ARS Market Quality and Handling
Research Unit in Raleigh, North Carolina, headed the study. Co-authors
include Brianna Hess and Claire Klevorn, both with North Carolina State
University in Raleigh. The team extracted peanut-skin polyphenolics and
treated them for use as an ingredient in a variety of foods, including
chocolate.
When added to milk chocolate, the peanut-skin powder increased the
levels of polyphenols in milk chocolate to those of dark chocolate
without making it bitter. This is important because evidence indicates
phenolics may impart a bitter taste, and theoretically, plants with
relatively high levels of phenolics can potentially taste the most
bitter. "We used food-grade maltodextrin, which is a sugar compound, to
create the powder, which decreases the bitter taste of the food
ingredient," says Dean. Volunteers who sampled a milk chocolate
optimally enriched with the peanut-skin powder and a "regular" milk
chocolate did not have a preference.
"While we have studied bioactivity of the extract in cell-culture and
test-tube studies, more research is required to gauge whether there is
a measureable benefit from consuming foods enriched with this extract,"
says Dean. "Allergenic effects of the extracts would have to be
thoroughly evaluated before inclusion in any foods, and labeling would
have to emphasize the addition of peanut products."
The study appeared in the November 2016 issue of The Journal of Food
Science. — By Rosalie Marion Bliss, formerly with the ARS Office of
Communications.
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