Anti-caking agents in powdered products may hasten
degradation of vitamin C instead of doing what they are supposed to do: protect
the nutrient from moisture.
Lisa Mauer, a Purdue University professor of food science;
Lynne Taylor, a professor of industrial and physical pharmacy; and graduate
student Rebecca Lipasek study deliquescence, a reaction in which humidity
causes a crystalline solid to dissolve. They wanted to understand how anti-caking agents protect substances such as vitamin C from
In Mauer’s laboratory, different anti-caking agents were
blended with powdered sodium ascorbate, a common form of vitamin C, and were
exposed to different relative humidities. Normally, sodium ascorbate deliquesces,
or dissolves, at 86% relative humidity and is stable below that level. Some
anti-caking agents, however, caused the degradation to begin at lower humidity
“The additives that the food industry puts in to make
these powders more stable didn’t help the vitamin C, and in some cases actually
made things worse,” Lipasek says.
Once vitamin C changes chemically, it no longer holds its
The findings suggest that foods made with powdered vitamin
C may lose the vitamin’s nutrients at a lower humidity than once thought. The
team’s findings were published in the Journal
of Food Science.
A variety of anti-caking agents were studied.
“Some of the agents act like little raincoats,
covering the particles and protecting them from moisture. Others will absorb
the water themselves, keeping it away from the vitamin C particles,” Mauer
says. “I really thought some of those anti-caking agents would help, but
The problem, according to the research, is the chemical
properties of the anti-caking agents themselves.
The water-repellent agents, which
act like raincoats, are mobile, Lipasek says. When they move around, they clump
together and leave some of the vitamin C uncovered. When that happens, moisture
is able to reach and degrade the exposed vitamin C.
The moisture-absorbing agents, which absorb the water at a
lower humidity than vitamin C, may be absorbing so much moisture that they
become saturated. When that occurs, Mauer says, the pH level around the vitamin
C can change, or water can move and interact with the vitamin C. Both of these
scenarios could lead to further reactions that lower the humidity at which
vitamin C deliquesces and changes from solid to liquid. Once the vitamin C
dissolves, it is unstable.
Next, Mauer and Lipasek plan to test more complex blends
that contain more ingredients along with vitamin C. They also plan to determine
how much water is necessary to destabilize vitamin C and how temperature
affects the destabilization of vitamin C with anti-caking agents.
Filed Under: Drug Discovery