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Blueberries Show
Antimicrobial Action
Antimicrobial effect of blueberry juice concentrate,
powder, and essence against Escherichia coli O157:H7 in liquid
medium
B. BERNIER and A. A. Bushway. Dept. of Food Science & Human Nutrition,
Univ. of Maine, 5735 Hitchner Hall, Orono, ME 04469-5735
Recent research has indicated that fruit products may inhibit the
growth of human pathogens, since antimicrobial compounds are naturally
present in fruit extracts. The objective of this study was to investigate
if blueberry juice concentrate, essence and powder could reduce
Escherichia coli O157:H7 ATCC 700599 in liquid medium. Blueberry
essence (1, 2.5, 5%, and 10% v/v), concentrate (1, 2.5, 5% and 10%, v/v),
or powder (0.5, 1, 2.5, 5% and 10%, w/v) was mixed into liquid medium
(Brain Heart Infusion Broth or sterile distilled water) and then
inoculated with 4-log cfu/mL of E. coli O157:H7. Uninoculated
controls were prepared for all treatments. The inoculated samples were
stored at 5 and 37 °C, and analyzed using the Spiral Biotech Plating
System at 1hour and 1, 3, 7, 10, 14, 21 and 28 days at 5°C; 1hour and 1, 3
and 5 day for treatments at 37 °C. Blueberry powder at 2.5% showed a 1-log
reduction at 24 h at and a 1.5-log reduction at 72 h at 37°C in BHI broth.
Blueberry juice concentrate at 5% showed the highest level of reduction,
3.5-log reduction at 72 h at 37 °C in BHI broth. Blueberry juice
concentrate at 5% showed only a 1.5-log reduction after 120 h at 5 °C in
BHI broth. Blueberry juice concentrate at 10% showed a 3-log reduction at
24 h in sterile water. Blueberry powder at 5 and 10% showed a 4.5-log
reduction at 24 h in sterile water. Blueberry essence has shown little
effect at 37 °C. This study indicates that blueberry concentrate and
powder may be effective in reducing E. coli O157:H7 in liquid
mediums.
Session 83D, Fruit & Vegetable Products: Processed fruit
8:30 AM - 12:00 PM, Thursday AM Room Hall N-1
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