Packaging
California
Table
Grapes
UNIVERSITY OF CALIFORNIA
DIVISION OF AGRICULTURE
AND NATURAL RESOURCES
PUBLICATION 1934
To order or obtain ANR publications and other products, visit the ANR
Communication Services online catalog at http://anrcatalog.ucanr.edu/ or
phone 1-800-994-8849. Direct inquiries to
University of California
Agriculture and Natural Resources
Communication Services
2801 Second Street
Davis, CA 95618
Telephone: 1-800-994-8849
Email: anrcatalog@ucanr.edu
© 1995 The Regents of the University of California
This work is licensed under the Creative Commons Attribution-NonCom-
mercial-NoDerivatives 4.0 International License. To view a copy of this
license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ or send a
letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.
Publication 1934
The University of California, Division of Agriculture and Natural Resources (UC
ANR) prohibits discrimination against or harassment of any person in any of its pro-
grams or activities on the basis of race, color, national origin, religion, sex, gender,
gender expression, gender identity, pregnancy (which includes pregnancy, child-
birth, and medical conditions related to pregnancy or childbirth), physical or men-
tal disability, medical condition (cancer-related or genetic characteristics), genetic
information (including family medical history), ancestry, marital status, age, sexual
orientation, citizenship, status as a protected veteran or service in the uniformed
services (as defined by the Uniformed Services Employment and Reemployment
Rights Act of 1994 [USERRA]), as well as state military and naval service.
UC ANR policy prohibits retaliation against any employee or person in any of its
programs or activities for bringing a complaint of discrimination or harassment. UC
ANR policy also prohibits retaliation against a person who assists someone with a
complaint of discrimination or harassment, or participates in any manner in an in-
vestigation or resolution of a complaint of discrimination or harassment. Retaliation
includes threats, intimidation, reprisals, and/or adverse actions related to any of its
programs or activities.
UC ANR is an Equal Opportunity/Affirmative Action Employer. All qualified appli-
cants will receive consideration for employment and/or participation in any of its
programs or activities without regard to race, color, religion, sex, national origin,
disability, age or protected veteran status.
University policy is intended to be consistent with the provisions of applicable State
and Federal laws.
Inquiries regarding the University’s equal employment opportunity policies may be
directed to: Affirmative Action Contact and Title IX Officer, University of California,
Agriculture and Natural Resources, 2801 Second Street, Davis, CA 95618, (530)
750-1397. Email: titleixdiscrimination@ucanr.edu. Website: http://ucanr.edu/sites/
anrstaff/Diversity/Affirmative_Action/.
To simplify information, trade names of products have been used. No endorsement
of named or illustrated products is intended, nor is criticism implied of similar
products that are not mentioned or illustrated.
WEB-10/18-CK/WS
WARNING ON THE USE
OF CHEMICALS
Pesticides are poisonous.
Always read and carefully
follow all precautions and
safety recommendations given
on the container label. Store
all chemicals in their original
labeled containers in a locked
cabinet or shed, away from foods
or feeds, and out of the reach of
children, unauthorized persons,
pets, and livestock.
Recommendations are based on
the best information currently
available, and treatments based
on them should not leave
residues exceeding the tolerance
established for any particular
chemical. Confine chemicals
to the area being treated.
THE GROWER IS LEGALLY
RESPONSIBLE for residues on
the grower’s crops as well as for
problems caused by drift from
the grower’s property to other
properties or crops.
Consult your county agricultural
commissioner for correct
methods of disposing of
leftover spray materials and
empty containers. Never burn
pesticide containers.
PHYTOTOXICITY: Certain
chemicals may cause plant
injury if used at the wrong
stage of plant development or
when temperatures are too high.
Injury may also result from
excessive amounts or the wrong
formulation or from mixing
incompatible materials. Inert
ingredients, such as wetters,
spreaders, emulsifiers, diluents,
and solvents, can cause plant
injury. Since formulations are
often changed by manufacturers,
it is possible that plant injury
may occur, even though no
injury was noted in previous
seasons.
http://anrcatalog.ucanr.edu/
mailto:anrcatalog@ucanr.edu
mailto:Permissions@ucanr.edu
http://ucanr.edu/sites/anrstaff/Diversity/Affirmative_Action/
http://ucanr.edu/sites/anrstaff/Diversity/Affirmative_Action/
Packaging California
Table Grapes
The authors are
Donald A. Luvisi, UC Cooperaive Extension , Kem County
Harry H. Shorey, Department of Entomology, UC Davis
James F. Thompson , Biological and Agricultural Engineering Department, UC
Davis
Tom Hinsch, USDA, Marketing Specialist, retired
David C. Slaughter, Biological and Agricultural Engineering Department, UC
Davis
This research has been supported by
the California Table Grape Commission,
the USDA-ARS,
and the University of California
The authors thank the many shippers for their patience and cooperation , which
made this research possible.
The senior author thanks Ann Senuta, Publications Coordinator, DNAR
Communications Services for guidance and counseling during the preparation
of this publication.
CONTENTS
Introduction ... . . .. .... ....... .. ... . . . ................. .. ... . . 2
Research .. ... .... .. .... ... .. ... .. ... ....... . ....... ... .. ... .4
Packing the Boxes ...... .... . ... ................ ... . . .. . 5
Box Material and Construction . ... ..................... .. . 5
Cultivar and Pack Volume .. ... .. ................ ... ... . .. 6
Cultivar ....... .. ... ... ....... . ....... ... ... ... 6
Growing region ........ . ............ . ...... . ... . 7
Package volume and soluble solids content . . ..... . ... 7
Depth of pack .. . .......... . ............... . .... 7
Overpacking ................................... 8
Box dimensions ............. ..... .............. 8
Inner packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Palletizing and Transporting Boxes to Cold Storage ........... 9
Forced-air Cooling ... ... ... ... ............... ... ....... 9
Initial Fumigation . .... .. .... .. .. . . .. ... ... ...... .... .. 11
Cold Storage ........ ... ... .. ................ ... ... .. . 12
Storage Room Fumigation .. .... ........ . ... . . . .... ... . . 13
Transportation ....... .. ... .... ............... . ...... .. 13
Reference s . .. .. ... ......... .. .... ... ......... ... ... .... ... . . 15
Cover and back cover photos by Don Luvisi
2 Introduction
The present practice of field-packing table grapes
directly into the boxes used to store, ship, and distribute
them has evolved from an earlier method of packing. In
early shipments table grapes, tree fruits, and other types
of fresh produce were packed naked or in sawdust in
containers that measured 35 by 42 inches, designed to
fit into refrigerated railroad cars.
In the 1950s, shippers began to experiment with band-
ing smaller, wooden table-grape boxes together on 35-
by 42- inch pallets that fit the same floor configuration
as the earlier containers. The standard wooden-box
dimension that evolved was 14 by 17 .5 inches, and it
came to be known as the "LA lug." These boxes were
stacked, six per layer, on 35- by 42-inch pallets. This
pallet size has persisted in the northern San Joaquin
Valley and the Coachella Valley where it has been used
to ship tree fruit and table grapes. However, in the
southern San Joaquin Valley, a larger pallet of 53 by 42
inches was adopted to accommodate LA lugs stacked in
layers of nine boxes each.
Initially, grape boxes were constructed entirely of wood
with wood-slat lids nailed in place. The inside depth of
LA lug boxes became standardized at 5.5 inches, based
on the availability and economics of using 5.5-inch-
wide lumber rather than on the optimal depth for best
grape quality during handling and shipment. Later, the
Technical Kraft Veneer (TKV) box was developed,
made from thin strips of wood sandwiched between lay-
ers of Kraft paper. Although the table-grape industry
still refers to all boxes with wood at each end as TKV
boxes, this designation is specific to the type of manu-
factured box mentioned above . In this publication we
will use the generic designation of "wood-end box" for
any box with ends made of solid wood or particle board.
In the 1950s corrugated fiberboard boxes were devel-
oped for packing and shipping horticultural crops.
Corrugated boxes gained favor for packing table grapes
when long-term storage is not required. The corrugated
box is relatively easy to recycle and is the least costly
box to purchase . During the 1970s boxes made of
expanded polystyrene were specifically produced for 3
packing, storing, and shipping table grapes. These boxes
were commonly called "Styrofoam," "EPS," or "foam"
boxes, and in this publication we will refer to them as
foam boxe s. In the last 20 years foam boxes have
improved, and they are now used for 12 to 15 percent of
the grape crop. The use of corrugated boxes has also
increased, especially for early-season fruit and fruit that
is not stored for long periods. Advantages and disadvan-
tages of wood-end , corrugated , and foam boxes are list-
ed in Table 1.
Through the early 1960s most fruit was loaded by hand
into railroad cars. But in the mid-1960s shippers began
using trucks for long-distance transport and started
loading produce on pallets using forklifts. A loaded pal-
let could hold 70 to 90 boxes ( depending on box type)
held together by steel or plastic straps.
Pallet loading made for efficient handling of produce
from the field to the market , but it introduced a new
range of problem s in terms of matching box size to pal-
let size. The range of box sizes had already expanded
well beyond the standard LA lug dimensions as new
box materials were developed. When shippers began to
use pallets for loading, box sizes had to conform to vari-
ous pallet sizes. In the early 1970s there were 18 sizes
of containers; by 1993 there were more than 90 box-
and-pallet combinations in use.
Little research has been conducted on table grape pack-
aging since the mid 1970s, when pioneering work by R.
Hinsch and R. E. Rij (1970); F. G. Mitchell, R. Guillou ,
and R. A. Par sons (1972); Nelson (1985); and F. G.
Mitchell, D. A. Luvisi, and G. Mayer (1985) focused on
factors that cause damage to the grapes after harvest.
From these early studies the following conclusions were
drawn .
Most shatter (the breaking of individual berries
from their stems on the bunch) occurs when table
grapes are packed into the box.
When various weights of Thompson Seedless
grapes were packed into a standard 1,210-cubic-
inch LA lug, packing 23 pounds of grapes resulted
in more shatter than packing fewer pounds of
grapes .
4 • In the late 1960s, the use of newly developed foam Research
boxes reduced bruising and shatter of packed
Thompson Seedless grapes that occurred in corru-
gated and wood-end boxes.
Shatter tends to increase as cold-storage time for
Thompson Seedless grapes increases.
In 1993 the California Table Grape Industry initiated an
extensive research project to evaluate containers for
table grapes. The project initially evaluated most of the
different box sizes, pallets, and materials available to
the industry for the following reasons.
• Packers have had to stock a large inventory of
matrials to satisfy the wishes of different receivers
because of the varied number of box and pallet
sizes.
Despite the wide range of box designs, types of
inner packaging materials, and methods for cooling
and fumigating packed table grapes, there has not
been a systematic study of table grape packaging
since the 1970s.
Although the wood-end box is the primary packing
container used, there are indications that corrugated
and foam boxes may be used more often in the
future.
• The industry standard (the wood-end box, 14 by
17.5 inches) can be severely overpacked when
filled with 23 pounds of fruit.
The produce industry has been moving toward
using a standard grocery -industry pallet measuring
48 by 40 inches, but these dimensions will not
accommodate the standard wood-end box of 14 by
17 .5 inches.
Increasing environmental concerns (and regulation
in some markets) have emphasized the use of pack-
ing materials that can be easily recycled.
The research objective was to determine how table
grapes can be moved from the field to the consumer in
the best possible condition. The research was conducted
during the 1993 and 1994 seasons. The 1993 effort was
directed toward evaluation of individual boxes. Over
4,000 boxes were packed with table grapes in more than
1,000 experimental combinations of the following vari-
ables.
Cultivar-Thompson Seedless, Perlette, Flame
Seedless, Ruby Seedless,and Redglobe (the only
seeded cultivar)
Growing regions-the Coachella Valley and the
San Joaquin Valley
Box construction materials-wood-end,
corrugated, and foam
Box dimensions (outside width and length)-
a) 14 by 17 .5 inches (the LA lug), which fits on
pallets that are 35 by 42 or 53 by 42 inches
b) 13.3 by 16 inches (sometimes called the
"MUM box"), which fits a 48 by 40-inch pallet
c) 12 by 20 inches (sometimes called the "shoe
box"), which fits on a 48 by 40-inch pallet
d) 16 by 20 inches (sometimes called the "met-
ric box"), which fits on a 48 by 40-inch pallet
Box depths-Depths in 1/2-inch increments for
weights between 18 and 25 pounds of packed fruit
Inner packaging-plain-packed and poly-bagged
Level or pack volume-quantity of fruit packed in
the box was calculated to bring the height of fruit in
each box to level-full, versus 10% overpacked
(above level-full) and 10% underpacked (below
level-full).
The poor structural integrity of some table-grape The 1994 effort was directed toward evaluating how the
boxes has led to breakage and fruit loss during most promising boxes, identified during the 1993
long-term cold storage and transportation. research, would protect the quality of grapes as they
• Cost effectiveness and competitiveness of packag- were moved through normal marketing channels in pal-
ing types and materials must be balanced with the letized units. Fruit was packed, palletized, and evaluat-
economic needs of the industry. ed as it went through the normal cycle of initial fumiga-
tion, precooling, storage, storage-room fumigation,
shipping by truck, and receiving at a distant terminal
market.
Packing the Boxes
The method used for packing table grapes is generally
the same among most growers. Grape clusters are
placed either directly into the box (plain pack) or into
bags (bagged) by hand. In each packing system clusters
are transferred twice-first from the vine into a field
box by the picker, then from the field box into a ship-
ping box by the packer.
The picker selects clusters for quality and maturity,
removing undersized, decayed, immature, and other
damaged berries before placing clusters in the field box.
Field boxes are sometimes moved to a central location
for packing (shed pack), but the majority of California
table grapes are packed in the field. The packer works
either on the ground or beside a wheeled stand that
accommodates the field box of clean fruit carried to the
packer by the picker. The stand can be equipped with a
scale and additional boxes for packing. As each box is
packed, clusters are selected or trimmed to fill the box
to its correct volume and final weight.
In these studies, high quality was defined as lack of
damage to the fruit caused by shatter, splitting, and
bruising. Most shatter occurs during packing of the
grapes, probably due to the sideways pressure from the
packers' hands, the sides of the box, and cluster-to-clus-
ter contact. Most splitting and bruising results from
compression when too many grapes are placed in a box
so that the fruit mounds above an imaginary line
between the tops of the opposing box ends. When a box
lid is forced into place over mounded fruit, splitting and
bruising result, mainly on berries that are touching the
lid or the bottom of the box.
A box is "plain packed" when fruit is placed cluster to
cluster in the box until the appropriate net weight is
obtained. Net weight of the standard plain-packed,
wood-end box in 1970 was 26 pounds; through 1995
that weight is 23 pounds in the San Joaquin Valley and
22 pounds in the Coachella Valley. However, it has been
recognized for some time that even these reduced
weights often result in overfilled boxes with lids that
must be forced into place, causing considerable bruising
and splitting of the berries.
Box Material and Construction
Choice of box material is often influenced by factors
other than maintaining the quality of the packed fruit
(Table 1). The preferences of the receiver and environ-
mental (recycling) considerations are more important in
some markets than in others, and these factors may dic-
tate the type of box to be used. In addition, cost consid-
erations can be very important; corrugated boxes are
usually lower in price than wood-end or foam boxes.
The humidity of the storage room and the length of stor-
age time will also affect the selection of box material.
Wood-end and foam boxes maintain their structural
integrity in high-humidity storage better than corrugated
boxes. Waxing corrugated boxes can improve their
strength, but it reduces their recycling potential, and is
rarely used. Foam boxes are preferred by some
exporters, since more product can be shipped due to
their light weight.
Box materials can have a noticeable effect on fruit qual-
ity immediately after harvest, both early in the harvest
season when the sugar content of the fruit is lower, and
later when the fruit is at full maturity. Thompson
Seedless grapes that were packed into foam boxes in
Delano, Calif., during the summer of 1993 had about 30
percent less shatter than those packed into corrugated or
wood-end boxes (Table 2). No consistent differences in
the amount of shatter were detected among grapes
packed in corrugated or wood-end boxes. However,
after six weeks of cold storage, shatter in the foam
boxes increased to a level that was equal to shatter in all
types of boxes .
Non-stored Thompson Seedless grapes packed in foam
boxes displayed less splitting and bruising than those
packed in corrugated or wood-end boxes (Table 2).
Foam box lids are less flexible than wood or corrugated
lids, and this discourages overpacking of foam boxes. A
bulging lid is often considered acceptable on a wood-
end or corrugated box but not on a foam box. Another
practice that leads to increased shatter and bruising is
overfilling a box to provide a bonus product for the
buyer.
The typical wood-end table-grape box has all four cor-
ners of each end panel "clipped ." The clipped-comer
5
6
'Mature harvest 'stored fruit" was harvested on the same date and from
the same field as mature harvest fruit but was held in cold storage for 6
weeks before evaluation.
design was developed to facilitate the circulation of air
during cooling and st
