This investigation was concerned with the reduction of
waste in raw vegetables and fruits between the times of harvest
and consumption. Reduction of spoilage in produce was attempted
by means of chemical and. physical agents as well as a combination
of both.
The first phase of the work consisted of an evaluation
of a number of chemical compounds with respect to their effectiveness
in reducing post-harvest spoilage. The second part
dealt with an evaluation of several transparent films applied
to raw produce as wrappers and their effect on the keeping
quality of the plant material until consumed. Finally combinations
of surface disinfection and overwrapping were evaluated
for effectiveness against raw produce spoilage.
1. Disinfection
Approximately 26 compounds were tested as aqueous
dips using 3 concentrations of each on 7 major vegetables and
2 fruits. The following types of compounds were studied.
1. Quaternary ammonium compounds (chlorides,
bromides and pyridinium derivatives)
2. Chlorine liberators (organic and inorganic)
3. Phenols (simple and poly-phenols)
4. Quinones and hydroquinones
5. Salts of fatty acids
6. SO₂ liberators
7. Benzoates
The chemical treatments were evaluated for each produce
by comparison with untreated controls using duplicate tests
with triplicate samples for each chemical and concentration.
Promising treatments were found for all but one produce (strawberries).
The treatments showing promise for each of Pascal celery
and Emperor grapes were further tested on a larger scale
uaing commercial size units of produce as test samples and long
term cold storage. Three chemical treatments for each product
were judged satisfactory enough to warrant further testing by
means of field trials. The chemicals found most promising for
celery were Onyxide, Cetab and Decco while Roccal, Dowicide C
and Phygon were selected for grapes.
A field test of the three above mentioned treatments
for Pascal celery was completed. One thousand bunches per
chemical were tested under commercial conditions of dipping
and storing. An equal number of untreated bunches was also
tested. Half-lots of each treatment were evaluated on each
bunch for 11 subjective characteristics and standard mold
and bacterial counts of each crate of celery were made after
8 and 14 weeks of storage.
On the basis of a statistical analysis of the results,
0.1% Decco of pH=5 can be recommended for the reduction of
general rot development in cold storage Pascal celery. Onyxide
and Cetab significantly reduce the development of mold but
commercial application cannot be recommended because the
amount of visible stalk injury was significantly increased
over that shown by corresponding untreated or Decco treated
celery.
2. Prepackaging
The following films were compared for their merit
in prolonging the salable life of raw produce. Pliofilm 75FF,
Pliofilm 75N2, Pliofilm 75P6A, Cellophane 300LSAT, Cellophane
300MSAT-86, Lumarith P-912, Dupont Acetate 100CA48, Polythene
and Kodapak II-130.
Wrapping techniques were also evaluated using the followng
variations; Complete seals, tent-flap closures, single
hole punctures, multiple punctures and windo bags.
The following products were studied: celery, tomatoes,
carrots, lettuce, cauliflower, chopped salad mix, spinach,
strawberries, raspberries, blackberries, and boysenberries.
Harvested produce was packaged both before and after
the removal of field heat. Behavior of the pre-packaged products
in both 33°F storage and subsequent 8O°F storage was
studied. Cold storage was extended as long as 120 days while
subsequent holding at room temperature varied widely from
produce to produce. Observations were made at regular intervals
for each product. Several hundred uniform samples were
evaluated for most products using duplicates of each treatment
for every observation period. Evaluation of most samples included
weightloss, C0₂ (and sometimes O₂) of the container atmosphere, mold and decay development, flavor, color, odor, wilting and shriveling.
The following conclusions were drawn:
All films and wrapping methods affect produce quality.
For each produce, treatments could be singled out which were
superior to unwrapped controls. However any particular film
and type of seal found to be superior for one produce was
often not acceptable for another fruit or vegetable. Among
the factors found to be critical for the proper choice of
treatment were type of produce, produce temperature when
packed, length of storage, and temperature of storage.
A. Cold Storage
For most products, the partially sealed, low
permeability MSAT containers and the completely
sealed Polythene wraps scored highst for overall
product quality. These treatments prevented the
accumulation of undesirable CO₂ while at the same
time protecting the produce against weightloss and
consequent wilting. For some produce, especially
berries, wilting was not apparent even in high permeability
films such as acetates.
B. Warm Storage
For produce with high respiration rates
(spinach, and berries) only acetate films were acceptable
as wraps.
The partially sealed low permeability films
maintained good quality in warm storage but the
high humidity within the package was conducive to
micro-organism activity. Thus, in many cases
samples disinfected prior to packaging in those
films improved the warm storage quality.
Disinfection also improved the quality of
tomatoes and chopped salad mix in acetate wraps.
Of the high permeability films, no significant difference
was found among the Dupont acetate, Lumarith and
Kodapak II.
The type of seal also did not affect the characteristics
of these wraps. The low permeability films differed
principally in the amount of CO₂, retained by the container
during storage. The Pliofilms retained the highest C0₂,
levels followed by LSAT and then MSAT Cellophane.
The sealed polyethylene, the single puncture and
tent flap MSAT wraps exhibited similarity, especially with
respect to C0₂ accumulation.
The multiple puncture low permeability wraps showed
characteristics between acetates and the last mentioned group.
Correlation between CO₂ accumulation and off-flavor
formation could be determined for most products. Higher CO₂
levels were tolerated at short storage intervals without off-
flavor formation by most products but the rate of change in
CO₂ tolerance varied from produce to produce. Correlation
between % weightioss and degree of wilting could also be expressed
as a function of the pre-packaging treatments used.
Storage infection was eliminated by all films independent
of the type of seal used.
It should be emphasized that only a study of the resuits
and relationships discussed under each product can
serve as a basis for future work and commercial application
of the methods presented in this work. / Graduation date: 1950
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26884 |
| Date | 25 July 1949 |
| Creators | App, Jean, Lorant, George John |
| Contributors | Worthington, Oliver J. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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