29B-6 |
Antioxidant and anti-microbial activity of polyphenols derived from phytic acid |
A. S. MOLENGRAFT1, J. W. Frost2, E. T. Ryser1, and G. M. Strasburg1. (1) Dept. of Food Science & Human Nutrition, Michigan State Univ., 336 G. Malcolm Trout FSHN Bldg., East Lansing, MI 48824-1224, (2) Dept. of Chemistry, Michigan State Univ., 528-A Chemistry Bldg., East Lansing, MI 48824-1322
There is rising interest in
use of environmentally friendly methods as alternatives to petroleum-based
production of food ingredients. Phytic acid obtained from steeping liquors of
grain processing was used as starting material for a simple two- or three-step
synthesis of two polyphenolic compounds, 1,2,3,4,-tetrahydroxybenzene (THB) and
2,3,4,5,-tetrahydroxybenzoic acid (THBA), respectively. These compounds bear
striking structural similarity to other polyphenolic compounds that are
effective inhibitors of lipid oxidation and of microbial growth.
The objectives of this study
were to evaluate the antioxidant and anti-microbial activities of THB and THBA.
Antioxidant activity of THB
and THBA was compared with structurally related compounds using three assays:
1) Peroxide value determination using the Schaal oven test with lard,
containing 0.01% or 0.005% antioxidant, as the lipid substrate; 2)
Thiobarbituric acid reactive substances (TBARS) in cooked ground beef
containing 0.01% antioxidant; and 3) Spectrofluorometric analysis of Fe2+-induced
autoxidation of liposomes.
Anti-microbial activity was defined by the minimum concentration of
compound needed to inhibit bacterial growth in culture media inoculated with 109
cfu of pathogen.
In the Schaal oven test, the
order of antioxidant activity was THB > THBA > gallic acid > alpha
tocopherol > protocatechuic acid.
Similarly, in the meat system, THB and THBA had the strongest
activities. In the liposome assay, gallic acid showed the strongest activity
followed by tert-butylhydroquinone > butylated hydroxytoluene > propyl gallate > protocatechuic acid
> THBA > THB ≈ alpha-tocopherol.
THB demonstrated strong anti-microbial activity. Growth of Escherichia
coli O157:H7 was inhibited at a THB concentration of 600 µg·mL-1;
Listeria monocytogenes and Salmonella Typhimurium were
inhibited at 800 µg·mL-1 THB. THBA showed no anti-microbial
activity.
Our results suggest that, depending on their
toxicity profiles, these derivatives of a low-value by-product of grain
processing could be highly effective, inexpensive compounds for enhancement of
food safety and quality.
Session 29B, Food Chemistry: Lipids, antioxidants and emulsifiers
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