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University of California 
College of Agriculture 
Agricultural Experiment Station 
Berkeley, California 







, L. Mehren, L. L. Morris, and Wendell Calhoun 
August 1947 

Contribution from the 
Giannini Foundation of Agricultural Economics 
Mimeographed Report No, 89 

G. L. Mehren,^/ l. L, Morris and Vfendell Calhoun^/ 


1, Compared to the total, there is relatively little consumer packaging 
of fruits and vegetables under way. Vegetables are being packaged in larger 
volume than are fruits. However, only spinach, tomatoes, salad mixes and 
soup mixes are commonly packaged throughout the state, 

2, Most consumer packaging at present is being done by commercial packers 
and is largely for local (2 to 3 days) distribution. Except for one cooperative 
group of growers, very little packaging is being done by producer or retailer 

3, Developmental and research work with a view toward long-distance 
shipment of prepackaged fruits and vegetables is under way. This work is 
concentrated on vegetables. Development of shipping-point packaging for 
distant sale may have important effects upon the California fruit and vege- 
table industries, 

4, Most enterprises concerned — from producer to package manufacturer, 
seem to be proceeding with caution, A need for factual information is obvious. 

5* The proper role of the Experiment Station in this development is not 
clear. An all-inclusive project on consumer packaging of fruits and vegetables 
does not seem desirable. However, cooperation between various interests within 
the Experiment Station, the research groups of the United States Department of 
Agriculture and industry agencies should be fostered. The research agencies 
need to acquire experience themselves before they will be in a position to 
make major contributions. To this end, cooperation in making trial shipments, 
and in following "pilot-type" operations should be given serious consideration. 
Help in solving specific problems as they arise is probably more desirable 
than initiating a project designed to cover the entire subject. From the view- 
point of economics, data could be obtained to measure several aspects of con- 
sumer demand. It is considered too early to inquire into the probable effects 
of packaging upon market channels, handling methods, structure of competition 
or costs, despite the fact that consumer packaging will probably have important 
effects upon these matters. 

1/ This is a preliminary report based upon a short survey. The questions at 
issue were: What is the extent of current packaging operations in California? 
What problems must be solved before packaging expands? What are the probable 
lines of development of packaging? How can the research facilities of the 
Experiment Station and the United States Department of Agriculture best be used 
in this development? 

2/ Assistant Agricultural Economist in the Experiment Station# 

3/ Assistant Olericulturist in the Experiment Station, 

4/ Agricultural Economist, Bureau of Agricultural Economics, United States 
Department of Agriculture, 



Products Packaged 

Very little consumer packaging is under way in California in proportion to 
the total supply of fruits and vegetables grown in the state. Although most 
fruits and vegetables have been packed in consumer units at one time or another, 
the practice has become established in only a few cases. Vegetables are receiv- 
ing much more attention than are fruits. Practically all packaging has been for 
distribution within the state. 

Spinach is being packaged in greater volume than any other fresh commodity. 
It is estimated that over 50 per cent of the spinach in the Los Angeles area 
is marketed in transparent consumer packages and that the same percentage is 
approached in the Bay area. Established enterprises are located in the Los 
Angeles area, the Bay area, and in the San Benito, Salinas, and San Joaquin 
valleys • 

Salad and soup or stew mixes are being packaged primarily by the same 
agencies that package spinach. The salad mixture is composed largely of 
shredded cabbage. The soup mixture also contains a considerable quantity 
of cabbage together with other vegetables such as carrots, turnips, celery, 
onions, and parsley. 

Tomatoes are being packaged on a fairly wide scale during the season that 
the supply is coming from out-of-state areas.' This is being done as a sub- 
sidiary operation to the necessary ripening and repacking operations of re- 
ceivers at the destination markets. 

The consolidation of onions and potatoes into consumer units varying from 
10 to 25 pounds has been practiced for several years. This is done at shipping 
point, at the wholesale warehouse, and at the retail store. 

The popularity of packaged spinach can be attributed to several factors. 
The sorting and washing improves its appearance and reduoes the work of the 
housewife. A large amount of waste material is eliminated. Year-round pro* 
duction results in a fairly stable supply and makes possible the use of the 
packaging facilities throughout the year. There is a year-round demand for 
the product, although it slacks off during the summer months. This relatively 
constant supply and demand are associated with fixed-price policies in buying 
and selling. Most of these advantages probably could be realized for certain 
other vegetables such as carrots, cauliflower, celery and lettuce. 

Aside from these vegetables, several have been packaged on an experimental 
or trial basis with a view toward expansion into commercial scale. Celery has 
been packaged in both the Bay area and the Los Angeles area. Lettuce is being 
packaged on a fairly large scale in the Los Angeles area by a cooperative 
association of grower-shippers. Cauliflower and broccoli have been packaged to 
some extent. Brussel sprouts, carrots, asparagus, and potatoes which have been 
peeled and processed are under consideration but to date little or no packaging 
has been done. 

In some instances packaging has been discontinued. This is true of some 
retail stores that attempted to package at the place of sale. At least one 
shipper has discontinued the packaging of cauliflower and another has dis- 


continued radishes. Operations have been terminated for a variety of reasons t 
no price differentials over bulk sale; interference with other operations, 
such as mixed-car sales of broccoli; inadequate supply of the product year- 
round; need to pack too many units to make up a practicable package. 

Current operations indicate that these products which can be kept high in 
quality, for which some processing is possible or weight elimination is signi- 
ficant, and which have both year-round demand and production, offer greater 
opportunity for consumer packaging. 

Except for the spinach operations, there seems to be much caution among 
the packers with an apparent wish that others undertake the preliminary and 
experimental work, particularly for shipment to distant markets.. 

Types of Enterprises 

Consumer packaging has been undertaken by all segments of tho industry 
from grower to retailer. In fact, the question as to where and by whom the 
packing will be done is probably the biggest issue that the industry faces. 

Growers and shippers have undertaken some packaging operations but for 
the most part their activities have been confined to collaboration in research 
and developmental activities.. Although considerable activity by growers and 
shippers is anticipated, at present a negligible amount of packaging is being 
done by individual firms. In some oases consumer packing operations have been 
discontinued by shippers. A cooperative made up of several large grower- 
shippers is engaged in developmental packaging on a commercial scale.l/ 

Commercial packers specializing in one or a few products account for most 
of the volume of vegetables now packaged. To illustrate the diversity of these 
operations, in one spinach-packing enterprise the consumer packing operation 
is a side line for a wholesale vegetable dealer and in another the packing is 
a side line for a spinach oannor. A large tomato importing enterprise has 
recently begun operations at Nogales, Arizona and comtemplates shipments into 
western cities.-' 

A few retail outlets are doing some packaging at the place of sale. How- 
over, this practice seems to be decreasing. The retail chain stores are doing 
some packaging at their wholesale level. This is true for repacked tomatoes 
and for potatoes. At least one chain store company is contemplating consumer 
packaging of various fruits and vegetables for their retail outlets. 

In addition to these enterprises there is considerable activity of a re- 
search or exploratory nature. The Western Growers Association has formed a 
research group and set up a private laboratory at Pasadena. This group is con- 
ducting holding tests and plans soon to undertake transit tests and pilot-plant 
operation. The manufacturers of packaging materials ore cooperating with this 

l/ Lettuce is being packaged as a commercial venture and the addition of 
several other linos is contemplated. 

2/ The Packer. April 5, 1947 

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and other agencies in making exploratory tests and trials. 

Methods of Procurement 

Some spinach packers contract their acreage in advance and exercise con- 
trol over harvesting operations* Others buy through regular -wholesale channels, 
sometimes using spinach from out-of-state aroas. The cooperative association 
mentioned above is supplied by its own members who have committed themselves 
insofar as possible to provide a stablo supply. VJlnter tomatoes that are pack- 
aged aro procured through the regular wholesale channels. It would appear 
that a stablo supply assured either by contract or by entering into production 
is probably necessary for the commercial packer. Those retailors who are doing 
somo packaging procure their commodities in the usual manner. 

Methods in Use 

Packaging methods, facilities, and techniques vary widely with the dif- 
ferent products and agencies. With a few notable exceptions, the operations 
aro on a rather primitive level. Some spinach operations are highly mochanizod 
with hand labor being used only for sorting, trimming, and placing in the bag. 
Tomato operations have a wide range in combinations of mechanization and hand 
labor. Tho packaging operations at retail stores have been almost entirely 
on a hand basis. The consequent high cost has discouraged packaging at tho 
rotail level. 

Three general typos of packages are used for consumer packaging. Bags of 
transparent cellulose film are used for spinach and salad and soup mixes. These 
bags aro usually closed by metal staples. Open top bags made of a transparent 
rubber hydrochloride film have been used on a commercial scalo for celery. 

A second method of packaging consists of placing tho vegctablo in a 
paper tray or "boat" and then ovcrwrapping tho unit with a transparent film. 
Maohinory such as has been used in tho baking industry is usod for this typo 
of packaging. 

A third type of packago consists of a cardboard box with a transparent 
film for a window. This packago is commonly used for tomatoes. 

In addition to the above, a method is under consideration wheroby the 
commodity is contact-wrapped and then tho wrapper film is sealed, 

Tho mechanical equipmont being used in packaging operations varios greatly. 
Estimatos of the investment nocossary for packing a given commodity would bo 
next to meaningless. 

Distribution Methods 

Methods of sale vary. However, where possible the product is packaged 
to orders already received. Due to the high perishability of the product, it is 
necossary to restrict tho pack to tho estimated daily requirement. The regular 
wholosale market outlets are being usod to a considerable extent as an outlet 
for packaged vegetables. In fact, somo packaging is being done on tho wholesale 

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markets in both the Los Angeles and Bay areas. 

Some demand promotion is being done by salesmen contacting the retail 
outlets* Apparently little or nothing has been done to promote demand :.xat the 
consumor level. 

The distribution of packaged vegetables has been limitod in extent and area 
as compared to the distribution given -wholesale packages. In genoral, distri- 
bution is limited to a truck radius. However, air shipment is being used to a 
limited extent. For example, spinach is regularly flown to several markets 
within a radius of one thousand miles. In so far as was determined, no company 
regularly ships carloads from California, Sinco at present refrigeration during 
transit and retailing is usually nonexistent, the only control of quality is 
speed of handling and recovery of unsold stock from the retailers. The limi- 
tation of sales to the retailer probably oporates to prevent gluts and unsold 
merchandise of poor quality. 

All operators apparently desire a stable price both in respect to buying 
and selling. Even those packers who are buying on a fluctuating wholesalo 
prico are attempting to maintain a fixed price to the retailer and apparently 
desiro the retailer to maintain a fixed prico to tho oonsumor. There has been 
at least one attempt to establish the wholesale soiling price by application 
of a mark-up formula based upon f,o,b, price of unpackagod produce, with a 
fixed margin for packaging. 

Very little time was spent with retailers. However, it is apparent that 
tho physical methods used to display and merchandise packaged produce vary as 
much as do the mothods used for unpackaged fruits and vegetables. A few stores 
have refrigerated display cases but they are the exception rather than tho rule. 
In general, tho packaged commodities are displayed alongside tho bulk produce 
at room temperature, 

A one day survey was made of 29 retail stores in Sacramento to determine 
tho extent to which packaged vegetables were being carried. The observations 
are tabulated in the following table. 

Retail Handling 


Displays of Packaged Spinach, Salad Mix and Tomatoes 
by 29 Retail Stores in Sacramento, April 10, 1947 

Sizo of 

Number of 
stores visitod 

Number of stores displaying packaged 

Spinach Salad mix Tomatoes 










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ah 1 J to 



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' With the exception of soup mix in one store, spinach, salad mix and 
tcmatoes were the only vegetables displayed in consumer packages. Only about 
one third to one half the stores were displaying these commodities on this date. 

There has been much discussion concerning the desirability of various 
films as packaging materials. However, there are practically no experimental 
data available concerning the benefits or harm to be expected from enclosing 
any given vegetable in films of various permeabilities under various conditions 
of temperature, humidity, and storage time.!/ 

In packaging at shipping point for local distribution, any one of several 
films can be utilized for packaging most vegetables. Perhaps some may have 
advantages over others, but most of the available films can at least be tole- 
rated for the short periods necessary for local marketing. In short, the pro- 
blems connected with local packaging seem to be mainly of a physical and 
economic nature. However, there are some vegetables that are so perishable 
that it would appear doubtful that consumer packaging could result in the 
delivery of a high quality product under the present methods of wholesale 
and retail handling even though the marketing period bo limited to a short 
one. Sweet corn, shelled peas, and shelled limas would fall in this class. 
It is very doubtful that the consumer package as such contributes to the 
storage life of any of tho vegetables now packaged. However, initial selec- 
tion of high grade produce, careful grading, rapid handling, and removal of 
deteriorated produce from the stores are all practices which tend to enhance 
the quality of packaged vegetables. The additional handling involved in 
washing, sorting, and packaging vegetables undoubtedly contributes to a more 
rapid rate of deterioration. The preparation of a salad or soup mixture 
undoubtedly increases the perishability of the components. 

The packaging of vegetables in wholesale units f orbreakddwn- and 'repacking 
at or near the point of sale is another possible development. Under such con- 
ditions, rapid and desirable handling after packaging will be necessary — 
especially if the transit period is a long one. The commodity, after transit, 
will have exhausted part of its storage life and initial quality and hence 
will be more perishable than a commodity pre-packed at point of production for 
local distribution. 

A third possible development, and one that is of primary interest to <-Cali> 
fornia producers, is the pre-packing at shipping point for sale at distant (in 
time) markets. Such a procedure poses many physical and physiological ques- 
tions and probably will be established only after considerable experience with 
local packaging and after much experimental and developmental work* Due to tho 
additional time involved, methods of precooling and refrigeration assume a 
major role. Continuous refrigeration will be needed for many vegetables. The 
characteristics of the packaging material and the master container used will 
probably be more critical under these conditions than for local packaging. 

1/ The relationship between packaging and -waste is discussed in the Packer of 

March 29, 1947. The Packer article "'Normal' Food Waste — Is It Irreducible?" 
is a condensation of an article by C. W. Hauck and W. L. Lonox of Ohio State 

Physiological and Technological Aspects 


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Although the first consideration will be to determine what materials can be 
used, there is a possibility that some packages may actually contribute to "the 
total storage life of soine vegetables. 

Considerable experimental and developmental type of work is under ■my on 
consumer packaging of vegetables. Much of the commercial packaging under way 
also is experimental, or, at least developmental in nature. 

As mentioned above, the Western Growers Association has established a 
research group which is working cooperatively with the staff of the California 
Institute of Technology and with industrial interests concerned. The work of 
this group is broad in scope covering a study of storage life under various 
temperature and humidity conditions, effect of gas concentration, methods of 
decay control, and techniques of washing, drying and packaging. Only holding 
tests are being conducted at present, but pilot-plant packaging and transit 
tests are planned. This group is progressing on the assumption that the 
practice can be made economically sound. Emphasis is being placed on the 
technical aspects of packaging operations. This group should ultimately be 
able to provide both practical and basic information. 

Lack of information on the characteristics of various packaging materials 
is one of the limiting factors to the prepackaging of fruits or vegetables for 
long-distance shipment. It will be necessary to conduct many storage tests 
in which vegetables and fruits are packaged taA held under controlled tempera- 
ture conditions. Observations should include weight loss, storago life, and 
in some oases, chemical changes. The research group of the Western Growers 
Association is doing controlled work of this nature. It appears that the 
Experiment Station could assist materially in developing information of this 

Along this line, information is needed concerning the value and limitations 
of holding fruits and vegetables in atmospheres of various COg and Og concen- 
trations. Research of this nature is under way or contemplated by commercial 
interests. The work of the Experiment Station, especially in the vegetable 
field, could well be expanded in this regard. 

Many technical problems of an engineering nature confront the industry. 
Progress in this field is another factor limiting the long-distance shipment 
of consumer-packaged vegetables. Work of this nature is receiving the attention 
of many allied interests and the work on vegetables is concentrated in the 
Western Growers' Assocation Research Group. The only obvious or request© d 
role of the Experiment Station was assistance in conducting trial shipments. 
This work will undoubtedly be in cooperation with the Bureau of Plant Industry. 

Economic Aspects 

Despite the small scale of current consumer-packaging operations in 
California, there are already clearly-apparent pressures which will almost 
inevitably lead to its expansion. Packaging offers profit opportunities to 
retailers, distributors, and to concerns presently engaged in canning, freezing 
or dehydrating. It should permit retailers to introduce into their produce 
departments the self-service methods now widely used in handling other food- 
stuffs. Demand for some packaged products will probably be high enough to 
cover additional costs of packaging, especially those products for which the 


need of home preparation is diminished. Uniformity of quality should be easier 
to maintain and the damage, waste, and contamination from handling py purchasers 
should be lessoned. Shipping-point distributors should be able to eliminate 
much -waste weight and off -quality produce before transit. Large-scale operation 
should make possible the use of mechanical techniques for packaging not readily 
adaptable by retailers or by wholesale receivers in terminal markets. With 
centralized packaging at shipping point, distributors should be able more 
effectively to control grade, size, sanitation and volume of shipment. Pro- 
duct differentiation, advertising and market oontrol should bo facilitated. 
Packaging of vegetables as a by-product to freezing, canning, and dehydration 
operations is already being investigated as a means of decreasing overhead 
costs per unit of output. 

If this expansion of shipping-point packaging occurs, it is almost certain 
that major changes in methods of marketing will also occur. Some functions will 
be shifted, new functions may be introduced and others eliminated. The intro- 
duction of packaging machinery will change the kind and volume of labor needed 
in produce marketing. Shifts in market channels similar to those associated 
with the introduction of packaging in other lines of foodstuffs can be expected 
to occur in produce marketing. Transportation will be speeded rnd refrigeration 
facilities expanded. 

In most staple-food lines in which the processors have packaged and 
branded the product, they have also extended their influence over the marketing 
process backward toward original production and forward toward final con- 
sumption. The first signs of this same development are appearing in the 
packaging of -fruits and vegetables. Packagers control seed, planting, har- 
vesting and price by contract with growers. Continuous efforts are made' to 
eliminate fluctuations in the buying prices of their products or in the selling 
prices of the packaged product or both. Processors appear to be willing to 
collaborate in periods of short supply or other difficulties. Some of them 
attempt to dampen daily prioe fluctuations and to regulate quality within 
narrow tolerances. Processors apparently want both the retail trade and con- 
sumers to become accustomed to uniform quality and price, both of which are 
to be associated with the brand. Removal of deteriorated products from retail 
stores by processors is intended both to control quality and to support price- 
maintenance programs. They recognize that deterioration in quality or appear- 
ance of a packaged and branded product may seriously depress demand for it, 
from which recovery may be very slow. Thus, as in foodstuffs for which pack- 
aging and branding have been introduced at the processing level, price, quality 
and volume control have quickly been introduced. With the low output thus far 
attained, packagers have not yet considered the applicability of fair-trade 
laws setting price floors or permitting resale price-maintenance contracts. 
No extensive advertising has been undertaken, although at least one California 
packer is considering the desirability of directing his advertising henceforth 
to consumers rather than to wholesalers. 

Extension of packaging may also have repercussions upon the functions 
now performed by wholesalers and retailers as well as upon the degree to 
which they can influence the marketing process. In other lines, the packagers 
of foodstuffs have gone directly to the consumers by means of advertising. 
As a result, the functions of the wholesalers and retailers have been con- 
stricted and their influence upon the producer has been lessened. Retailers 
no longer greatly affect the demand for many packaged products, and some 
independent wholesalers have been reduced almost to the status of branch 


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houses or -warehouses. For example, grocers have little choice in respect to 
carrying many branded products like cigarettes and virtually no leeway in 
pricing them. Packaging in consumer units at shipping-point, if associated 
with the expected extension of stable-price policies, will also constrict the 
price-making or price-registering function which is presently so important 
a phase of the wholesale produce market. Retail distribution will also be 
affected if shipping-point packaging of fruits and vegetables expands. The 
development of the refrigerated, self-service paokage store will probably 
be hastened. While additional costs in handling and refrigeration will be 
incurred by the retailer, savings in labor and spoilage costs should at least 
partly compensate for the increase. If the packager is able successfully 
to differentiate his product and to carry his advertising directly to con- 
sumers, he will effectively command consumer demand. The larger is the scale 
of the packaging operations, the greater will be the influence of the pack- 
ager and the greater will be the changes in functions, methods of handling 
and channels of trade. 

Equally important changes in the structure of competition may occur, 

At present, many shippers of fresh fruits and vegetables can do little to 
affect market price. About the only factor related to profit which they 
can control in the short run is the amount marketed. However, if processing 
develops on a large scale, the volume of purchases by individual packers 
may become sufficient either directly or indirectly to affect selling prices 
in the field. There is already some evidence that the competitive status 
of the various agencies involved in produce marketing may shift if large 
scale packaging develops. 

There is probability that some of these changes will occur within the 
next several years. Changes in marketing structure may be similar to those 
which have oocurred in other lines of packaged foods. The effects of these 
changes upon the marketing mechanism will spread to growers, handlers and ocn- 
sumers. When they occur they will offer highly interesting and important 
fields of research. However, until they do actually occur, and until the 
technology of packaging shakes down into reasonably stable molds, they offer 
little if any research opportunity. At present there is a line of precedent 
in other products, and the first bare indications that the same line of de- 
velopment may be reproduced in packaged fruits and vegetables. But there 
are a large number of directions along which packaging may be developed. It 
is far too early to investigate these changes in market structure. 

Two other lines of inquiry suggest themselves in the economic aspects 
of packaging — costs and demand. It would bo useful to determine the additions 
to total costs attributable to packaging of fruits and vegetables at various 
levels of the marketing process, by various techniques and at various scales 
of output. This could probably be done for the few enterprises continuously 
operating now. However, techniques of packaging are yet unsettled. Shipping 
point packaging and packaging at terminal markets distant from points of pro- 
duction are in the very earliest stages of development. There are a few small 
scale, experimental or pilot-type operations in which Experiment Station 

1/ Structure of competition is defined in terms of the degree of product 
differentiation; the degree to which the volume of any single seller can affect 

market price and the degree to which freedom of entry into the industry pre- 

' *i ' • 2 E 


personnel might collaborate. But until some stability is introduced into 
methods of packaging and shipping, cost comparisons would be almost without 
meaning. This stability must await the solution of several technological 
probloms and the development of new marketing facilities. 

There does appear to be an opportunity for research into the demand for 
packaged products. A series of questions can be posed and for most of them 
it should be possible even at this early stage to find answers. What factors 
affect the price of packaged fruits and vegetables at retail? How are such 
factors interrelated? What is the effect of condition of product upon level 
of demand? How does the degree of preparation for uso affect the differential 
between packaged and bulk products? How does the display of the products 
affect the differential between the two types? How effective is branding in 
obtaining a price differential? Are there any significant seasonal variations 
in the level of demand for packaged products? 

It might be possible to collaborate with one or more of the agencies 
currently packaging products for retail sale within the state. If it were 
also possible to establish connections with several grocers retailing the 
product, controlled experiments could provide data to answer these questions. 
It probably would be neoessary to effectuate an agreement by which to adjust 
display, quality and price within reasonable limits, and to obtain data on 
the relationship of packaged and bulk demands. Similar studies could be 
worked out as other phases of packaging become sufficiently settled to justify 
research. No over-all project encompassing all probloms involved in the con- 
sumer packaging of fruit and vegetables is desirable at present. 


The physiological characteristics of the vegetable may largely deter- 
mine the success of prepackaging in relatively tight containers. Although 
it will bo necessary to make tests under commercial conditions, there is some 
esperimental information available that may be of valuo in predicting and ox- 
plaining results. Following are notes on spinach, head lettuce, tomatoes, 
celery, salad and soup mixes, carrots, asparagus, cauliflower and broccoli. 
Although this material is incomplete in many respects, it may serve to point 
out the many physiological factors that are involved. 

In the following, "storage life" means the time required for the freshly 
harvested vegetable to reach an unusable condition. It is an approximate rule 
that the storage life of many vegetables is doubled or tripled by lowering tho 
temperature about 18 degrees Fahrenheit within usual temperature limits. 

It is an established experimental fact that a reduction in oxygen-content 
of tho atmosphere can result in either benefit or harm to the vegetable de- 
pending upon the concentration and time involved. In like fashion, tho carbon 
dioxide concentration may be either beneficial or harmful. When a vegetable 
is enclosed in a transparent consumer package, there is a definite tendency 
for tho oxygen to be reduced and the carbon dioxide incroased within the pack- 
age. It will be necossary to evaluate this effect under commercial conditions. 

.ifcoi) %o Jo: 


, Spinach 

Storage Life .— Two to throe days at 70 degrees Fahrenheit? five to six 
days at 50 degreos Fahrenheit; ten to twenty days at 32 degrees Fahrenheit, 

Causes of Deterioration . — Water loss; yellowing; decay. 

Storage ^Requirements , — High relative humidity and 32 degrees Fahrenheit 
optimum; package- ice desirable for bulk spinach; refrigeration required for 
any marketing period exceeding two days. 

Effect of Low Oxygen .-- It has been reported (8 that spinach held 
in 0.8 per cent Og for three days at 68 degrees Fahrenheit was superior in 
appearance and taste to that held in normal air. Low Og concentration has 
resulted in lower respiration (8) and better retention of ascorbic acid (10), 
Changes in Og concentration between 5 and 21 per cent seem to have little 
effect on 02 consumption or COg production. 

Effect of High Carbon Dioxide ,— Very little work is published on this. 
One set of tests (2) indicates that spinach is more tolerant of high COg 
than certain other vegetables; a concentration averaging about 50 per cent 
(80-30) for a two day period at 65 degrees to 40 degrees Fahrenheit did no 
harm to spinach. Another investigator (14) observed injury when spinach was 
held for four days in a concentration of 20 per cent COg at 39 degrees Fahren- 
heit, 50 degrees Fahrenheit, and 59 degrees Fahrenheit. It has been reported 
(10) that COg will hasten asoorbic aoid loss at 75 degrees Fahrenheit but has 
little or no effect at 50 degrees Fahrenheit, 

Magnitude of Respiration ,— The respiration rate of spinach is high com- 
pared with most other vegetables. The respiration rate decreases with storage. 
Following are approximations based on data reported by Platenius (7): 


Mgr. COg 
per Kg,-Hr. 

B,t,u, per 

ton per day 

Pounds of ice 
per ton per day 















Preparation for Packaging ,— Spinach is washed; sorted for foreign ma- 
ter iaT7~d^a^~Telive^7~^tcTT~^oots and coarse stems are removed; and excess 
water removed before packaging. Precooling would undoubtedly be of value. 

Elimination of Weight ,— The amount of unusable material removed when 
spinach is pre-packed varies considerably. Estimates by pre-packers fall 
in the range of 30 to 60 per cent, Rasmussen and Platenius (12) have esti- 
mated that 10 ounces of packaged spinach is equivalent to 24 ounces of bulk 

1/ Numbers in parenthesis refer to reference citation at end. 


IQ Oft 




Effect of Packaging .-- There are practically no data available on the 
effect of consumer packages on storage life or nutrient content of spinach. 
The opinion has been expressed that "store life" is lengthened by packaging. 
Others (12) hold that pre-packing spinach renders it more perishable. Both 
results probably occur under different commercial conditions. The package 
retards water loss on the store shelf and may possibly have some benefit by 
creating a favorable atmosphere. The extra handling and bruising probably 
contribute to the deterioration of the spinach. The net result of packaging 
spinach is probably a somewhat lengthened storage life under most conditions. 

Platenius (9) has reported that none of the films commonly used are 
sufficiently permeable to oxygen to permit of normal respiration by spinach 
in a sealed bag. 

Conclusions .— » The scale of spinach packaging indicates that it is already 
a well established product. Partial preparation for home use is undoubtedly 
the major factor in its popularity. Methods of handling for marketing periods 
of more than two or three days are yet to be worked out. Improvements in local 
distribution methods would seem desirable since the packaged spinach observed 
in retail stores often leaves much to be desired. 

Holding tests to determine the possibilities and limitations of various 
films under different temperatures and for various periods are needed. Appear- 
ance, taste, and nutrient content should be considered. The present method 
of closing the bag by staples may be superior to a tight seal. If a tight 
seal is used, vent holes should be provided unless such are shown to be un- 
necessary. Methods of packaging are sufficiently settled to make cost of 
packaging studies possible. Sufficient data could be collected to measure 
various aspects of consumer demand. 

The physiological characteristics of Swiss chard and other greens are 
closely similar to those of spinach. 

Head Lettuce 

Storage Life .— Three to four days at 70 degrees Fahrenheit; six to 
ton days at 50 degrees Fahrenheit; fifteen to twenty-five days at 32 degrees 

Causes of Deterioration .-- Wilting, discoloration, decay. 

Storage Requirements . — High humidity and 32 degrees Fahrenheit desirable. 
Refrigeration essential for all marketing periods exceeding two days. 

Effect of Low Oxygen .— Very little experimental work published. Nelson 
(6) has reported that' redheart and sunken lesions on outer leaves wore caused 
by a deficiency of 0g # 

Effect of High Carbon Dioxide .— It has been reported (2) that a high 
COg content maintained for two days was not harmful to head lettuce of the 
Ioeberg variety. However, Thornton (14) has reported that a COg content as 
low as 13 per cent has produced injury on hoad lettuce when held for one week 
at 32 degrees or 39 degrees Fahrenheit. The lettuce became soft, lost crisp- 

.* a - 

)ld7B "f> 


ness and soon rotted when exposed to this concentration of COg, 

Magnitude of Respiration ,— The respiration rate of lettuce is more or 
less intermediate when compared with other common vegetables. Following are 
some approximations based on data of Platenius (7): 


Mgr. COg 
per Kg.-Hr. 

B,t,u, per 

ton per day 

Pounds of ice 
per ton per day 















Preparation for Packaging ,-- Washed, trimmed, and excess water .removed, 
Precooling desirable 

Elimination in Weight ,— Maximum of about 10 per cent. 

Effect of Packaging ,-" Tests conducted in Florida (13) showed that a 
pliofilm wrapper aided in the retention of weight, color, texture, and palat- 
ability of lettuce held at 37 degrees Fahrenheit or 70 degroos Fahrenhoit,' 
The thinnest wrapper gave the best results and folded bags were superior to 
sealed bags. Cellophane is being used as a heat-sealed overwrap for lettuce 
for local distribution. No deleterious results have been reported. 

Conclusions .— If a sealed package is used for long markoting periods, 
some venting may be required. Apparently a heat-soalcd cellophane wrapper 
can be used for local distribution. 

The fact that head lettuce is in fairly constant supply and demand should 
contribute to its adaptability to consumer packaging. However, there appears 
to be little gained by way of preparation for the table. The effect of packag- 
ing upon table quality remains to be demonstrated. Sufficient volume has been 
reached to make consumer-demand studies possible 


Storage Life, — Mature greent five to ten days at 75 dogrees Fahrenheit; 
ton to twenty days at 65 degrees Fahrenheit; twenty to thirty days at 55 degrees 
Fahrenheit (minimum temperature). Pinks: three to four days it 75 degrees 
Fahrenheit; four to eight days at 65 degrees Fahrenheit; eight to fifteen 
days at 55 degrees Fahrenheit, 

Causes of Deterioration ,— Normal ripening, softening, shrivelling, decay. 

Storage Requirements . — Subject to "chilling injury". Should not be 
exposed to temperature below 50 dogrees Fahrenheit for prolonged periods 
(over five to eight days). Will not ripen above about 77 degrees Fahrenheit, 
Limits of storage 50 degrees to 75 degrees Fahrenheit. Limits of ripening 



— • voldU^Ti esj.S-'grs'i laoooi^. 

^unix.'!«>3M ■•••♦v .'V ;t iOv,'- nx nd-Cui^/nrf i^. 

~ .I... ,. . . . ..,«, i. i -I.,,. ■ 

I -reft ,6*tPV 0f * 4 * iao 

13 «->«^ 25 1 


55 degrees to 75 degrees Fahrenheit, 

Effect of Low Oxygon.—* Can prevent ripening of mature green and cause 
phys iological breakdown. 

Effect of High Carbon Dioxide . — High CO2 concentrations for a period 
of two days have been reported to rotard ripening slightly (2). Thornton 
(14) reports that the tomato is very susceptible to carbon dioxide injury. 
A concentration of 10 per cent maintained for four days at 32 degrees, 39 
degrees, 50 degrees or 59 degrees Fahrenheit proved harmful. Complete break- 
down of the tomato was reported. 

Magnitude of Respiration .— » Compared with other vegetables, tomatoes have 
a relatively low respiration rate. Following are some approximations based 
on data of Platenius (7): 


Mgr. CO2 
per Kg.-Hr. 

B.t.u. per 

ton per day 

Pounds of ice 
per ton per day 















Preparation for Packaging .—- Washing and possibly waxing. 

Elimination of Weight .— NdPP Possible. An increase might occur. 

Effect of Packaging . — Tests with pliofilm in Florida (13) gave only 
beneficial results from wrapping tomatoes. Ripening was retarded somewhat. 
There have been some tests using ordinary paper wrappers. The rosults aro 
conflicting but it seems logical to conclude that ordinary paper wrappers 
have no practical effect on ripening. However, under commercial conditions, 
improper ripening has been observed in -consumer packages that were sealed. 
On the other hand, accelerated ripening has been reportod (3) following wrap- 
ping—this was attributed to tho trapping of a volatile material. 

Conclusions . — It is doubtful that the present method of putting tomatoes 
in a cardboard box with a cellophane window has any practical effect on their 
physiology. However, a couple of holes in the sides of the box for ventilation 
would do no harm and might be of value. If a sealed overwrap is used, some 
ventilation should be provided unless tests show that this is not needed. 

Tomatoes must be at least breaking in color before packaging in cartons 
containing 3 or 4 fruits since a given lot of mature green fruits ripftn very 
unevenly. Wrapping individual fruits in a transparent film may have practical 
possibilities for mature green tomatoes, 


Tests are needed to determine the effect of trapping volatiles such as 

i. ) 


■ v. . 
'Ot ■ 

* ■ - 


ethylene that are given off by tomatoes during ripening. 
Data could be obtained for cost or demand studies. 


Storage Life .— Five to ten days at 70 degrees Fahrenheit; fifteen to 
twenty-five days at 50 degrees Fahrenheit; and sixty to ninety days at 32 
degrees Fahrenheit. 

Causes o f Deterioration .— Water loss, browning of cut surfaces, decay. 

Storage F c quirements . — High humidity and 32 degrees Fahrenheit. Re- 
frigeration required for marketing periods exceeding four or five days. 

Effect of Low Oxygen .— No data available. 

Effect of High Carbon Dioxide .— Thornton (14) has reported that 25 per 
cent C02 produced injury at 50 degrees Fahrenheit but not at 32 degrees or 
39 degrees Fahrenheit. A concentration of 50 per cent produced injury at 32 
degrees ana at 39 degrees Fahrenheit. 

Exposure for three days to an atmosphere in which the COg averaged 50 
per cent resulted in slight injury (2). Even 20 per cent gave very slight 
browning of tho vascular tissue. 

Magnitu de of Res pira t ion . — Celery is intermediate to low in respiration 
rate. The foilbufitlg is based on data of Pontzer included in United States 
Department of Agriculture Circular 278. 


Mgr . C02 

per Kg-."Er* 

B.t.u. per 

ton per day 

Pounds of ice 
per ton per day 


















Prepara tion for Packa ging, — Washing, trimming, removal of exocss water. 
Pre-cooling would be desirable during warm weather. 

Eli mination of Weight . — Would depend on trimming practiced. Probably 
about 20 per cent (5). 

Ef fect of Packa ging,— Tests with pliofilm conducted in Florida (13) in- 
dicated" that an over-all wrap or a stretch wrap resulted in a marked retention 
of market and table quality. Partial wrappers of parchment paper have been 
used for several years. Work (16) reports that full coverage with a parchment 
paper wrap resulted in retention of table quality. Waxed paper wraps were also 
of definite value. 


. ■ . 

■ V 


Conclusions .— The close trimming of celery leaves should contribute 
to its storage life. Continuous refrigeration would bo dosirablc, but pre- 
packaging for local distribution would have advantages under present methods 
of display, A tight seal should be avoided for long marketing poriods until 
moro is known of the possibilities and limitations of various films. 

Salad and Soup Mixes 

Storage Life .— One to two days at 70 degrees Fahrenheit; two to four 
days at 50 degrees Fahrenheit; and six to twelve days at 32 degrees Fahren- 

Causos of Deterioration *— Weight loss, development of slime and decay, 
discoloration, possibly loss of nutritive value. 

Storage Requirements .— High humidity and 32 degrees Fahrenheit, Re- 
frigeration required for periods exceeding two days. 

Effect of Low Oxygen .— No data; probably desirable down to at least 
5 per cent. 

Effect of High Carbon Dioxide .— No data; probably desirable up to 15 
to 20 per cent. 

Magnitude of Respiration .— No data; probably intermediate compared 
with other vegetables. 

Preparation for Packaging. — Washing, trimming, slicing or dicing, removal 
of excoss water. 

Elimination of Weight .— Probably 20 to 30 per cent of the weight of 
the bulk vegetables comprising the mixture. 

Effect of Pa ckaging .— The not result of the complete procedure is to 
make the components much more perishable. However, the final product could 
be handled only in packaged form. 

Conclusions.— Work is needed to detormino the storage life and loss 
of nutritive value of those mixtures under various conditions. 

Carrots — Topped 

Storage Life .— Five to fifteon days at 70 degrees Fahrenheit; twenty 
to forty days at 50 degrees Fahrenheit; and sixty to ninety days at 32 degrees 

Causos of Deterioration .— Water loss, decay, sprouting, rooting. 

Storage Requirements .— High Humidity and 32 degrees Fahrenheit optimum. 

Effect of Low Oxygen .— An O2 concentration of 2.3 per cent at 68 de- 
grees Fahrenheit, resulted in sorious injury to carrots (8); but 4,8 per cent 
at the same tcmporature gave no injury. 


Effect of High Carbon Dioxide .—* Thornton (14) found carrot roots very 
tolerant of high C02» Others {!) (2) have reported a beneficial effect from 
high C02. 

Magnitude of Respiration ."- Carrot roots have a relatively low respira- 
tion rate compared to many other vegetables. The following are approximations 
based on data of Platenius (7)s 


Mgr. CO2 
per Kg.-Hr. 

B.t.u. per 

ton per day 

Pounds of ice 
por ton per day 












i 6 



Preparation for Packaging .— Removal of tops, washing, possibly waxing. 

Elimination of Weight .— Approximately 20 per oent when compared with 
bunched carrots. 

Effect of Packaging .— Pliofilm bags and wrappers have been reported to be 
beneficial in retarding loss of quality of both topped and bunched carrots (13). 

Conclusions .— A beneficial rather than harmful effect could be expected 
from packaging topped carrots in the materials commonly used. The packaging 
of carrots should present fewer problems than most vegetables. However, aside 
from retention of quality, few advantages could be visualized. 


Storage Life .— Two to three days at 70 degrees Fahrenheit; five to eight 
days at 5C ( degrees Fahrenheit; and fifteen to twenty Tive days at 32 degrees 

Causes of Deterioration. — Fiber development, loss of sugar, water loss, 
opening of tips. 

Storage Requirements . — High humidity and 32 degrees Fahrenheit desirable, 
refrigeration essential for any marketing period exceeding two days; refriger- 
ation desirable for all marketing periods. 

Effect o f L ow Oxygen .— According to one investigator (8) a lowered 0 2 
content of thb~air is beneficial down to about 3 per cent- at 68 degrees Fahren- 
heit, below this point injury occurs. The limit is lower (about 1 per; cent) 
at 50 degrees Fahrenheit. Low 0 2 injury is characterized by longitudinal 
depression in the upper region of the stalk. Heavy wax coatings can also 
cause this injury. It has been shown (10) that low 0 2 contributes to the 
retention of ascorbic acid by asparagus at temperatures of 50 degrees Fahren- 
heit and 68 degrees to 73 degrees Fahrenheit, 


71 f 


18 . 

Effect of High Carbon Dioxide * — It has been reported (2) that a C0 2 . 
content of 25 to 30 per cent \ms beneficial at a temperature of 60 degrees to 
70 degrees Fahrenheit if the holding period was limited to one day. If the 
time was prolonged to two days, then the result was sometimes harmful. Con- 
centrations of 40 per cent for one day were harmful. Platenius and others 
report that a concentration of 28 per cent was not harmful when prolonged for 
a three-day period at 32 degrees, 39 degrees, 50 degrees, or 59 degrees Fahren- 
heit. Others reported that 50 per cent was harmful at all temperatures. 
Injury consisted of the development of water-soaked areas or a browning of the 
outer bud scales. Both Platenius (10) and Thornton (15) state that adding f| 
to the storage atmosphere at room temperature results in an increased rate 
of ascorbic acid loss. However, Platenius states that at 50 degrees Fahr- 
enheit, added C0 2 results in better retention of ascorbic acid. 

Magnitude of Respiration . — Asparagus has one of the highest rates of 
respiration of all vegetables. The rate decreases during storage. Following 
are some approximations based on data of Platenius (7). Asparagus trimmed 
for prepacking would have a higher respiration rate than indicated here. 


Mgr. C0 2 
per Kg.-Er. 

B. t. u. per 

ton per day 

Pounds of i 
per ton per 



Fahrenhe it 













Preparation for Packaging .— Washing, trimming, and removal of excess 
water would be necessary. Immediate cooling to near 32 degrees Fahrenheit 
would be desirable. 

Elimination of Weight .— It is estimated that 25 to 50 per cent of the 
weight of asparagus could be eliminated for prepacking. 

Effect of Packaging .— Cellophane bags inverted over regular bunches of 
asparagus were used on a trial basis in a shipment of California asparagus to 
New York City in 1934 (11 ). Two grades of cellophane were used; both lots 
showed condensation of moisture and some increase in mold and were not received 
favorably by the trade. These results are of limited application to the pre- 
semt^prbblemsrdf consumer, pabtaging,': but -TnayV/be '-indicative}, fit woulduappeRr 
that the packaging of asparagus could be either beneficial or harmful. Injury 
from low 0 2 would seem very likely unless' precautions were takan to avoid this. 

Platenius (9) has reported that none of the films used for packaging are 
sufficiently permeable to 0 2 to permit normal respiration by asparagus if the 
package is sealed. 

Conclusion.— The prepackaging of asparagus would appear to offer possi- 



bilities. However, injury due to low CU and high COg might occur. Closure 
of hags by stapling is probably desirable. If the bags are closed tightly, 
vent holes should be provided until found unnecessary. Immediate cooling 
followed by continuous refrigeration to the consumer would be desirable. Ex- 
perimental tests are needed and should include appearance, taste, and nutri- 
tive content. 

Cauliflower and Broccoli 

Storage Life. — Two to four days at 70 degrees Fahrenheit; eight to twelve 
days at 50 degrees Fahrenheit; and thirty to sixty days at 32 degrees Fahren- 

Causes of Deterioration . — Water loss, decay, yellowing of broccoli, 
browning of cauliflower. 

Storage Requirements . — High humidity and 32 degrees Fahrenheit optimum. 

Effect of Low Oxygen .— Somewhat beneficial in retarding loss of ascorbic 
acid in broccoli (10). A lowered 0 2 content of the air probably advantageous 
down to about 5 per cent. 

Effect of High Carbon Dioxide . — A short exposure (two days) to con- 
centrations of 30 to 50 per cent have shown no harmful effect on broccoli or 
cauliflower (2). Thornton (14) has shown that cauliflower will tolerate 25 
per cent C0 ? for one week at 32 degrees, 39 degrees, and 50 degrees Fahren- 
heit but 5Q r i>er cent was- harmful. 

Magnitude of Respiration .— No data are available for cauliflower. The 
respiration rate of broccoli is very high ~ see asparagus rates for an approx- 

Preparation for Packaging .— Trimming, possibly washing, segmentation 
of cauliflower. 

Elimination of Weight .-- Very little in case of broccoli; up to 50 or 
60 per cent in case of cauliflower. 

Effect of Packaging . — Pliofilm wraps and bags have been reported to be 
of benefit (13). Tests in retail stores in Ohio (4) indicate that packaging 
extends the "shelf life". 

Conclusions.— For long marketing periods the containers should not be 
sealed unless tests show that this is feasible. Long-distance shipment of 
these vegetables should be preceded by careful tests. Packaging of these 
commodities for local distribution can probsbly be practiced safely on the 
basis of what is now known. 

">s o 1 d 




1. Brooks, Charles, etal. 1932: Effect of solid and gaseous carbon dioxide 

upon transit diseases of certain fruits and vegetables. U. S. D. A. 
Tech. Bui. 318. 

2. Brooks, Charles, Bratley, C. 0., and McColloch, L. P. 1936: Transit 

and storage diseases of fruits and vegetables as affected by initial 
carbon dioxide treatments. U. S. D. A. Tech. Bui. 519. 

3. Caruso, Joseph D», and Harvey, R. B. 1935: Wrapping tomatoes. Food 

Industries 7:375, 376, 416. August 1935. 

4. Hauok, Charles W, 1946: Shelf life of fresh fruits and vegetables can 

be lengthened.' Ohio Bimonthly Bui. 31: 100-103. 

5. Hauck, C. W. and Lenox, W. L. 1947: Tare weights and wastes in marketing 

fresh fruits and vegetables. Farm and Home Research (Ohio Bimonthly 
Bui.) 32: 71-76. 

6. Nelson, Ray. 1926: Storage and transportational diseases of vegetables 

due to suboxidation. Mich. A. E. S. Bui. 81. 

7. Platenius, Hans. If 42: Effect of temperature on the respiration rate 

and the respiratory quotient of some vegetables. Plant Physiol. 17 : 

8. Platenius, Hans. 1943: Effect of oxygen concentration of the respiration 

of some vegetables. Plant Physiol. 18: 671-684. 

9. Platenius, Hans. 1946: Films for produce — their physical character- 

istics and requirements. Modern Packaging October, 1946. 

10. Platenius, Hans, and Jones, Josephine Brown. 1944: Effect of modified 
atmosphere storage on ascorbic acid content of some vegetables. Food 
Research. 9: 378-385. 

11« Pentzer, W. T«, etal. 1936: Precooling and shipping California aspara- 
gus. Calif. A. E. S. Bui. 600. 

12* Rasmussen, M. P., and Platenius, Hans. 1946: A preliminary survey of 
the pre-packaging of vegetables and fruits in New York State and the 
New England States. N. Y. State College of Agr. A. E. Mimeo. 557, 

13. Stahl, A. L. , and Vaughn, P. J. 1942: Pliofilm in the preservation 

of Florida fruits and vegetables. Fla. A. E. S. Bui. 369. 

14. Thornton, Norwood C. 1931: The effect of carbon dioxide on fruits and 

vegetables in storage. Contrib. Boyce Thompson Inst., 3: 219-244. 

15. Thornton, Norwood C. 1937: Carbon dioxide storage. X . The effect 

of carbon dioxide on the ascorbic acid content, respiration, and ph. 
of asparagus tissue. Contrib. Boyce Thompson Inst., 9: 137-148. 

16. Work, Paul. 1935: Loss of weight from celery during marketing as in- 

fluenced by wrapping, trimming, temperature and humidity. Proc. 
Amer. So. Hort. Sci. 33: 569-578. 

1 -4 I