256
FLORIDA
STATE
HORTICULTURAL
a 6-day ripening period beginning on the day of
incipient color development. The fruits were held
at 68 °F for the remaining 16 hours daily.
SOCIETY,
1964
The 100°F fruits had the highest acid content.
There was no effect of temperature on soluble
solids or dry weight.
A significant variety-temperature interaction
was found for firmness of the fruits.
Certain
lines were much firmer at 90° and 100 °F for 8
hours daily than some of the varieties and they
were as firm as fruits held only at 68°F.
The effect of temperature on color was simi
lar for all varieties.
at 80° and 90°F.
The best color was attained
Fruits held at 100°F for eight
hours daily were colored
as well as or better
than fruits held continuously at 68°F.
The acid content was
increased by holding
the fruits at 90 or 100°F daily but not at 80°F.
LITERATURE CITED
1. Duggar, B. M. 1913. Lycopersicin, the red pigment
of the tomato and the effect of conditions upon the develop
ment. Washington Univ. Studies 1: 22-45.
2.
Hall, C. B. 1964. The effect of short periods of high
temperature on the ripening of detached tomato fruits. Proc.
Amer. Soc. Hort. Sci. 84:501-506.
3.
MacGillivray, J. H. 1934. The variation in tempera
ture of tomatoes and their color development. Proc. Amer.
Soc. Hort. Sci. 32:529-530.
4. Rosa, J. L. 1926. Ripening and storage of tomatoes.
Proc. Amer. Soc. Hort. Sci. 23:1-10.
5.
Sayre, C. B., W. B. Robinson, and T. Wishnetsky.
1953. Effect of temperature on the color, lycopene, and caro
tene content of detached and of vine-ripened tomatoes. Proc.
Amer. Soc. Hort. Sci. 61:381-387.
EAR SIZE AND WEIGHT CHARACTERISTICS OF
FLORIDA SWEET CORN
ear size characteristic mentioned in the United
R. K. Showalter
Florida Agricultural Experiment Station
Gainesville
Ear characteristics of sweet corn at present
are
quite
different
from
the
one-inch
ears
of
wild corn which grew in Mexico in 5200 B. C.
(6). Breeders have sought long ears and a full
husk of dark green color with numerous flag
leaves (7). The number and length of husk flag
leaves are normally considered in variety evalua
tion.
Corn husks wrap around and extend above
and below ears to varying degrees. Tip fill, a cri
tical
factor
for
high
quality,
shank
and
flag
lengths are influenced by nutritional and spacing
factors during growth (13).
Sweet corn ear size is an important economic
factor although ears are retailed by count.
The
packed crate containing 4V2 to 6^ dozen ears
is the grower's unit of sale. Florida sweet corn
is graded and sold as U. S. Fancy or a percentage
of U. S. Fancy.
The larger, more mature ears
are graded U. S. Fancy and packed 4% to 5 dozen
ears per
crate.
The smaller less mature ears
that do not meet the minimum requirements of
U. S. Fancy, are specified as a percentage of
fancy (75 percent, 80 percent, etc.) and are
packed 5 to 6Y2 dozen ears per crate. The only
Florida Agricultural''Experiment Stations Journal Series
No. 1993.
States Standards for Green Corn (12) is length,
with a minimum of 6 inches required for U. S.
Fancy. Since this grade standard became effec
tive 10 years ago, Florida has increased its an
nual sweet corn production from 4.4 million to
8.8 million crates (1). Over a dozen varieties
have been grown in this period. Although each
variety has different ear characteristics, all pro
duce ears over 6 inches long.
In a recent study of consumer demand
(2)
the characteristics which appealed to consumers
were
freshness,
size.
On the New York City market, ears av
color,
size,
and
uniformity
of
eraging 7 inches in length brought a 7 percent
higher
price
than
6
inch
ears
(4).
Although
buyers have placed much emphasis on husk fea
tures, other segments of the trade are increasing
their demands for prepackaging with partial or
complete husk removal at the shipping point (3).
Freight and refrigeration charges are less than
one-half as much for trimmed prepackaged cauli
flower
as
they
were
for
cauliflower
in
their
jacket leaves (10).
In preparing corn for home
use, it is reported
(8)
that 35 percent of the
total ear weight in the husk is removed as husk
and trimmings. Research last year showed that
shelf life of sweet corn could be extended by
trimming the shank (9).
The purpose of this paper is to present infor
mation on physical characteristics of sweet corn
SHOWALTER: SWEET CORN
TABLE
1.
257
Ear Length and Filling of Cote of Nine Varieties of
Commercially Packed Sweet Corn in Everglades Area in
May and June,
1961.
Husked Ear Length
Variety
Filled Ear Length
Ave.
Range
Ave.
Range
In.
In.
%
%
106
7.7
6.5 - 9.5
95
69 -
100
Florigold 107
7.7
6.8 -
8.8
89
69
-
100
R-8
8.4
6.0 - 9.5
90
67 -
100
Iobelle
8.1
6.5
- 9.0
95
73 - 100
Wintergarden
8.4
6.5
- 9.2
92
75 -
Gold Cup
7.6
6.5
- 8.5
89
71 - 100
Silver Queen
8.3
7.8 -
8.8
97
94 -
100
Silverliner
8.1
7.5
- 9.5
91
75
-
100
Hybrid 31
8o9
7.5
- 9.8
95
86 -
100
Florigold
TABLE
2.
Ear Length Distribution
in Different Months
Sampling
Ears
Period
No.
for
100
Iobelle Sweet Corn Harvested
in Everglades Area.
Husked Ear
6
Length - Inches
7
8
9
Percent of Total Ears
Early April,
63
380
7
71
22
Early April,
64
538
12
72
16
177
2
64
34
405
3
25
68
4
60
2
22
74
2
Early May,
Late May,
63
63
Early June,
61
FLOHIDA
STATE
HORTICULTURAL
SOCIETY,
1964
ears as they are packed for shipment. Crates of
grade if the grower was packing more than one
commercially packed sweet corn were opened and
grade.
the ears were measured, weighed, and counted.
to 8.9 inches among varieties, and the range of
The average ear length varied from 7.6
ear lengths varied
Length Characteristics
Measurements
of ear lengths
almost 4
inches.
Although
some ears in each lot measured were 100 percent
filled with kernels, other ears had as low as 67
and filling of
percent fill.
To determine seasonal effects on ear
cobs were obtained for nine varieties of sweet
length, 10 lots of the highest grade Iobelle ears
corn in the Everglades area during late May and
were measured during April and May, 1963 and
early June, 1961. To obtain a representative sam
1964.
ple of each variety, six crates were selected at
periods and presented in Table 2 with the June,
random over a one-half day period when loads
1961 data. The distribution of ear length among
of corn were delivered to the precooler.
The ear
These data were grouped into four time
1560 ears showed a gradual increase in 8 and 9
lengths of the six yellow and three white varie
inch ears and a decrease in 6 and 7 inch ears
ties in Table 1 were obtained from the highest
from early April to early June.
TABLE 3.—Variations in Ear Weight of Iobelle Sweet Corn Within
Crates, Among Crates, Grades, Growers, and Harvest Dates.
Crate
Grade
Ear Weight - Pounds
Ears per
No.
Crate
Ave.
Range
No.
Grower No.
Fancy
Percentage
Percentage
1963
1
59
.69
.4 -
.9
56
.64
.4 -
.8
3
55
.70
.5 -
.9
1
79
.48
.3 -
.7
2
71
.50
.4 -
.7
2,
May 1,
1963
1
58
.69
.4 -
.9
2
57
.69
.5 -
.9
.9
3
59
.69
.4 -
4
57
.65
.4 -
.9
5
60
.62
.4 -
.9
1
65
.56
.4 -
.8
2
63
.53
• 3 -
.8
3
71
.51
.3 -
.8
Grower No.
Fancy
April 5,
2
Grower No.
Fancy
1,
3, May 2,
1963
1
55
• 80
.5 -
1.2
2
57
.78
.5 -
1.0
3
56
.79
.5 -
1.0
4
55
.76
.4 -
1.0
5
57
• 82
.5 -
1.1
SHOWALTER: SWEET CORN
grams with an increase in length of about 1 inch.
Weight Characteristics
Ears 7.0 - 7.25 in. long increased 85 grams as
Weight differences are used to separate vege
tables
such
as
tomatoes,
potatoes
melons into size classifications.
and
the diameter increased % inch.
water
Florida growers
increased V2 inch.
Each of the 294 ears was also weighed after
determine the suitability of ears for the fancy or
of
fancy
grades.
Many
ears
husking.
were
To
illustrate
The husk averaged 30 percent of the
total ear weight, and the amount of husk was
weighed from lots of sweet corn sorted into one
or two grade classifications.
very similar for all sizes.
the
variations which were found, three lots of Iobelle
Diameter Characteristics
corn from three growers in the Everglades area
were selected
(Table 3).
Ears over 7.75
inches long increased 150 grams as the diameter
use no weight or dimension sizing equipment to
percentage
259
For the fancy grade
Although ear diameter is not a common mea
packed by growers No. 1 and 2, ears within in
sure of size for fresh market corn or a factor in
dividual crates had a 0.5 lb.
the grade standards, it has been used by pro
(0.4 to 0.9) range.
Percentage of fancy ears from the same growers
cessors for separating ears of different maturi
also had
ties.
a 0.5
lb.
(0.3
to
0.8)
range.
When
The diameters of ears in the husk were
measured by passing ears through rings gradu
grower No. 3 harvested corn of the same variety
one day later than grower No. 2, he packed only
ated in
one grade consisting of much heavier ears with
294 ears of Iobelle harvested in early April (Ta
a weight range of 0.7 lb.
(0.5
to
1.2)
inch increments.
Diameters of the
ble 4) ranged from 1% to 2% inches.
within
of
crates.
%
646
ears
of
Iobelle harvested
Diameters
in late
May
(Everglades area) ranged from 1% to 2% inches.
On April 10, 1964, 294 ears of Iobelle sweet
corn were weighed, measured, and divided into
Diameters of 580 ears of Gold Cup
5 diameter and 4 length groups (Table 4). Ears
area in June) ranged from 1% to 2% inches. A
2 inches in diameter increased an average of 40
range of 1% to 2Y2 in. was found among 400 ears
TABLE
4.
Distribution of Ear Weights
Also Weight Losses
Ear
Ear Diameter
Length
Husked
in Diameter
from Husking.
1-7/8
2-0/8
1
Total Ear Weight
Inches
and Length Groups.
in Husk -
2-1/8
(Zellwood
Inches
2-2/8
2-3/8
in Husk - Grams
Under
7.0
201
224
252
7.0
-
7.25
215
236
270
300
7.5
-
7.75
223
250
290
328
361
232
624
307
330
382
Over
7.75
Weight Loss
All Lengths
30
29
from Husking - Percent
31
■^■Data from 294 ears Iobelle variety on 4-10-64.
32
32
FLORIDA
260
STATE
HORTICULTURAL
of Silver Queen (Zellwood area in June). The
average ear diameter for both the Gold Cup and
Silver Queen varieties was 2% inches.
The distribution of ear diameters for Florigold 106 (Table 5) showed that 61 percent of the
ears in one lot were under 2% inches in April,
and only 13 percent of a second lot were in this
size group
in
May.
Among the
Florigold
106
ears sorted into diameter groups, there was a
marked increase in ear weight as ear diameter
increased.
There was a slight increase in ear
length with increased diameter.
Husking and Trimming Characteristics
Ears of corn are pulled from the stalk by
breaking the shank with the hand.
Since much
SOCIETY,
averaged 10.5 inches, and the shanks averaged
3 inches
(Table 6).
readily
of
shank
observed
and
without
ear
length
removing
are
the
(862 ears)
33 percent of the ear length.
In preparing sweet corn for consumer pack
aging or retail display varying amounts of husk
are removed.
When ears of 5 varieties harvested
in May and June were weighed before and after
complete husking, 34 to 44 percent of the total
ear weight consisted of husk (Table 7). Iobelle
harvested in April had 30 percent husk (Table
4). When only shanks and flag leaves were
trimmed from four lots of ears, the weight loss
averaged 12 to 19 percent of the weight before
trimming.
Discussion
husk.
of corn were measured in 1963 and
shanks ranged
from 2 to 7 inches long and consisted of 26 to
not
When the length of the husked ears of six lots
Among the four lots sam
pled in the Zellwood area, the
of the shank is covered by the outer husk, the
proportions
1964
The
data
on
ear
characteristics
obtained
during the spring seasons of three years show
general lack
of uniformity
in
ear
size within
1964, the shank lengths were also measured. For
crates, among crates, among growers, and with
two
in lots having the same grade designation. Ears
grading above U. S. Fancy are being shipped
varieties
harvested
in
the
Everglades
in
April, the combined length of ears and shanks
TABLE
5.
Ear Diameter,
Weight and Length Characteristics of Two
Lots of Florigold
106 Sweet Corn.
Ear Diameter
Ear
Characteristics
2-1/8
Over
2-1/8
120 Ears
Distribution, %
in Husk - Inches
Under
2-2/8
(60 per crate)
2-2/8
5-8-63
13
39
31
17
Ear Weight,
gnu
261
301
330
385
Ear
In.
7.5
8.0
8.0
8.2
Length,
244 Ears
Distribution, %
(61 per crate)
4-9-64
61
31
8
0
Ear Weight,
gm.
238
278
318
0
Ear Length,
In.
7.5
7.8
8.0
0
SHOWALTER: SWEET CORN
by some growers, and others are combining wide
ranges of ear sizes.
Florida sweet corn is graded
and packed in the field by unskilled labor, and
difficulty is
being
encountered
in
meeting the
261
and a maximum shank length of 3 inches com
pared to the 6 inch ear and 6 inch shank require
ments of the U. S. Fancy grade.
demands for more uniform ear characteristics.
The wirebound crates used for sweet corn
were designed for ears with no protruding tips
Packaging firms believe the U.S.D.A. grades fall
and shanks
short of serving their needs for uniform fruits
and vegetables (5). Chain store buyers state that
grade inspection is meaningless because grade
standards are so broad.
The present 5 dozen ear pack of U. S. Fancy
Florida sweet corn does not provide a good index
of the husked ear characteristics.
Differences in
ear diameter and husk characteristics affect the
amount of space required and the weight of a
5 dozen package.
(11). Packing ears trimmed to fit
inside the crate would improve the appearance of
the pack. Close trimming also offers opportunities
to extend shelf life and reduce shipping weight.
Although the data obtained in this study are in
sufficient for formulating new sizing or grading
procedures, there is an indication that certain
changes in preparing sweet corn for shipment,
such as mechanical trimming and sizing would
be beneficial to the industry.
The range of variation within
a grade is reduced primarily by increasing the
number of grades.
indicate clipped ears.
The Florida Department
of Agriculture in its
Seal of Quality program
has recently defined a higher corn grade which
will require a minimum ear length of 7 inches
TABLE 6.
LITERATURE CITED
Florida growers use only the
U. S. Fancy grade because other U. S. grades
Ear
1.
Florida Agricultural Statistics—Vegetable Summary—
1963 issue. Fla. Dept. of Agr. 1963.
2. Folz, W.
E. and A. C. Manchester.
Chainstore
Merchandizing and Procurement Practices. U. S. Dept. Agr.
Marketing Research Report 417. 1960.
3.
Ginn, J. L.
Progress and Trends in Prepackaging
Florida Fruits and Vegetables. Proc. Fla. State Hort. Soc.
75: 287-289.
1962.
and Shank Length of Four Varieties of Commercially
Packed Sweet Corn.
Variety and
Date
Ear & Shank
Ears
Length
Shank Length
Ave.
Range
Percent
Shank
%
No.
In.
6-5-63
48
10.9
3
2-6
30
6-11-63
48
11.1
4
3-6
33
In.
In.
Gold Cup
Silver Queen1
6-19-63
108
11.1
3
2-4
26
6-10-64
120
12O2
4
2-7
32
244
10.5
3
1-5
27
294
10.5
3
1-5
28
Florigold 1062
4-9-64
Iobelle2
4-10-64
^Produced in Zellwood area.
Produced in Everglades areae
262
FLORIDA
TABLE
7•
STATE
Ear Weight Loss
HORTICULTURAL
1964
from Husking and Trimming.
Percent
Average Ear Weight
Ears
Variety
SOCIETY,
Loss
Grams
No.
Husked
In Husk
233
344
228
34
300
318
196
38
R-8
360
261
164
37
Wintergarden
360
352
196
44
Silver
360
321
203
37
Iobelle
Florigold
106
Queen
Trimmed
In Husk
Gold Cup
48
329
282
14
Gold Cup
48
352
308
12
Silver Queen
108
382
335
12
Silver Queen
120
402
327
19
husk removed,
shank and
flag
leaves removed.
4.
Hartman, John.
Quality and Related Factors In
fluencing the Price of Sweet Corn in the New York City
Market. Proc. 1958 Sweet Corn Quality Conference, Cornell
Univ., Dept. Vegetable Crops, Publ. 66: 12-15. 1958.
5.
Hunte, R. B.
Grades and the Packager.
Produce
Marketing 7: 48-56.
Oct., 1964.
6.
Mangelsdorf, P. C, R. S. MacNeish, and W. C.
Galinat. Domestication of Corn. Science 143: 538-545. Feb.
7, 1964.
7.
Pearson, Oscar.
What Can the Plant Breeder Do
in Developing Sweet Corn Varieties and Quality?
Proc.
1959 Sweet Corn Quality Conference. Cornell Univ., Dept.
Vegetable Crops, Publ. 72: 27-35.
1959.
8.
Pecot, R. K. and B. K. Watt. Food Yields Summarized
by Different Stages of Preparation. U. S. Dept. Agr. Hand
book 102. 1956.
9.
Showalter, R. K. Shank and Husk Trimming Effects
on Sweet Corn Storage Life.
Proc. Fla. State Hort. Soc.
76: 308-312. 1963.
10.
Stokes,
D.
R.
How
Good
Packaging
Benefits
the
Consumer. Speech at Annual Meeting, National Association
of Marketing Officials. Denver, Col., October 15, 1963.
11.
Sweet Corn Brings Premium Prices in All-Bound
Crates. Package Research Laboratory Bui. 344. April, 1953.
12.
U. S. Standards for Green Corn. 19 F. R. 2221, U. S.
Dept. Agr., May 18, 1954.
13.
Warren, J. A. Stands, Yield, and Quality in Ulster
County Sweet Corn. Proc. 1959. Sweet Corn Quality Con
ference, Cornell Univ., Dept. Vegetable Crops, Publ. 72:
2-13. 1959.
STUDIES OF SOUTHERN PEA LIPOXIDASE
F. W. Knapp
Florida Agricultural Experiment Station
Gainesville
Introduction
Lipoxidase catalyzes the oxidation of cis-cis
1, 4-pentadienoic fatty acids, such as linoleic, to
Florida Agricultural Experiment Stations Journal Series
No. 1996.
hydroperoxides. Because the latter have two con
jugated double bonds, their concentration can be
estimated by the amount of absorbance at 234
ni/A. (5).
Lipoxidase in varying amounts has been re
ported in a number of legumes (2)
(3)
(4) and
in sweet corn (7).
Reiser and Fraps (7) showed
a
degree
relatively high
of
lipoxidase
(designated as "carotene oxidase")
activity
in the seeds
of several varieties of the southern pea, Vigna
sinensis.
The work reported here was designed