FREZZA D., MOCCIA S., FILLIPINI DE DELFINO S., CHIESA A.
Abstract
Fresh-cut lettuce in increasingly being used in salad bars
and fast food restaurants partly because of value added to the product during
its preparation and also due to the delivery in a ready to eat condition. The
primary factors of this added value are low temperature and modified atmosphere
packaging. They are used to maintain freshness, extend shelf life, ensure safety
and promote sale. This study was conducted to evaluate the effect of active
and passive modified atmosphere with different temperatures to keep the quality
of fresh-cut butterhead lettuce (Lactuca sativa L.). Butterhead lettuce was
harvested at the commercial maturity stage. External leaves were removed and
the inner leaves selected, washed and packaged in multilayered polyolefin bags
(PD 961-EZ) with passive and active (5% O2: 5 % CO2) modified atmosphere. Bags
were stored for 7 days at 1s C, 7 s C and air temperature. Samples were taken
for analysis at 0, 1, 4 and 7 days. The organoleptic evaluations included determination
of visual quality and colour changes (a* value and hue angle). The O2, CO2 and
ethylene concentrations in the packages were measured. Visual quality was not
affected significantly in either modified atmosphere for every storage temperature.
Colour changes of fresh-cut lettuce and ethylene concentration were similar
in both modified atmosphere. Active and passive modified atmosphere at 1s C
were the best treatments in terms of fresh-cut butterhead lettuce keeping.
Keywords:
oxygen, carbon dioxide, ethylene, temperature, overall visual
quality