We investigated the effects of packaging
atmosphere and three levels of irradiation dose
(Repetitive High Energy Pulsed Power, -
RHEPP) on microbial populations, vitamin
retention, and display color attributes of ground
beef patties stored either chilled or frozen. Beef
knuckles and beef fat were coarsely ground,
sampled and analyzed to achieve 20% fat,
mixed, ground through a 1/8 in. plate, and
processed into 1/4-lb patties, which were
sealed either aerobically or nitrogen-flushed.
Patties were not irradiated or irradiated to 1.5
or 3.0 kGy, chilled, and displayed at 37 ± 4EF
for 6 days under 150 foot-candles of Deluxe
Warm White fluorescent lighting in an open-top
display case defrosted at 12 hour intervals.
Hunterlab Instrumental color was measured
daily. The experiment was replicated three
times. Aerobically packaged patties were
lighter, more yellow, more discolored, and less
red (all P<.05) than nitrogen-flushed patties
over the 6-day display. Nitrogen-flushing for
irradiated patties resulted in higher (P<.05)
retention of thiamin, but riboflavin was not
affected (P>.05). At $ 1.5 kGy, aerobic and
lactic acid bacteria were reduced (P<.05), and
no E. coli and coliforms survived. Nitrogenflushing
combined with irradiation resulted in
more stable, intensely red colored patties, which
retained more thiamin. The effect of irradiation
on various flavor notes was minimal and generally
diminished in nitrogen-flushed compared to
aerobic packages.
