Increase in consumption of fresh cut produce over the past decade has resulted in
a rise in incidents of food borne outbreaks due to pathogens. Conventional techniques of
sanitizing washes may not be effective since the organic matter released from the fresh
produce use up the free chlorine thus reducing the sanitizing potential of wash water just
when it is needed most and a heat treatment step to kill pathogens cannot be applied if
the purpose is to consume fresh produce. Electron beam (e-beam) irradiation was used to
treat cut cantaloupe, cut roma tomatoes, baby spinach, romaine lettuce which were
surface inoculated with a cocktail of Salmonella and E. coli O157:H7. Results showed
that irradiation reduced Salmonella and E. coli O157:H7 significantly with increasing
doses at 0.2, 0.4, 0.6, 0.8, and 1.0 kGy. The D10-value for Salmonella on irradiated cut
cantaloupe, cut roma tomatoes, baby spinach, and romaine lettuce was found to be 0.71
kGy, 0.64 kGy, 0.19 kGy, and 0.23 kGy respectively. The D10-value for E. coli O157:H7
on the produce listed above was found to be 0.73 kGy, 0.54 kGy, 0.18 kGy, and 0.20
kGy respectively.
Low dose e-beam irradiation was found to be an excellent tool for ensuring the
reduction of spoilage organisms and extending shelf life in cut cantaloupe, cut roma
tomatoes, baby spinach, romaine lettuce, strawberries, and green onion. The produce
were tested for 12 days of storage for aerobic plate count, yeast and mold, lactic bacteria,
color, texture, and respiration rate as a function of irradiation doses 0, 1, 3, and 5 kGy.
Aerobic plate counts, yeast counts, and lactic acid bacteria were reduced appreciably at
all doses tested on all commodities. Molds did not grow on any samples including
control for cut cantaloupe, cut tomatoes, and green onion but for the other commodities,
mold was reduced at the same rate as yeasts and vegetative bacteria. Lactic acid bacteria
were reduced at all doses while the reduction was highest with 5 kGy in all commodities.
When irradiated with 5 kGy, during storage, strawberries, spinach, and green onion
displayed wet, soggy and mushy appearance, romaine lettuce leaves were wilted, had a
translucent midrib and brown pigmentation. E-beam irradiation increased respiration rate
for all samples on day 0 compared to non-irradiated control irrespective of the
commodity type and the effect was dose dependent. Firmness reduced appreciably for
cut roma tomatoes, baby spinach, strawberries, romaine lettuce, and green onion with
increasing doses. Cut cantaloupe was low in firmness but the effect was not dose
dependent.
Irradiation at low doses is a promising tool to reduce pathogens and enhance
keeping quality of cut cantaloupe, cut tomatoes, baby spinach, romaine lettuce,
strawberries, and green onion. Irradiation is to be implemented as part of an overall
HACCP plan and is not meant to replace existing control measures.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2011-05-9178 |
| Date | 2011 May 1900 |
| Creators | Adavi, Megha Sarthak |
| Contributors | Castillo, Alejandro |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | thesis, text |
| Format | application/pdf |
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