Title: Grapefruit investigations
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Permanent Link: http://ufdc.ufl.edu/UF00072346/00001
 Material Information
Title: Grapefruit investigations
Series Title: Citrus Station mimeo series
Alternate Title: Blue Albedo in grapefruit
Burgundy grapefruit
Physical Description: 4, 3 leaves : ill. ; 28 cm.
Language: English
Creator: Deszyck E.J
Ting, S. V., 1918-
Oberbacher, M. F
Citrus Experiment Station (Lake Alfred, Fla.)
Florida Citrus Commission
Publisher: Florida Citrus Experiment Station :
Florida Citrus Commission
Place of Publication: Lake Alfred FL
Publication Date: 1960
 Subjects
Subject: Grapefruit -- Varieties -- Florida   ( lcsh )
Grapefruit -- Quality -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references.
General Note: Caption title.
General Note: "September 21, 1960."
Funding: Citrus Station mimeo report ;
 Record Information
Bibliographic ID: UF00072346
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 75266561

Full Text




Citrus Station Mimeo Series 61-2
September 21, 1960


Grapefruit Invest igations
I. Blue Albedo in Grapefruit
E. J. Deszyck and S. V. Ting


The consumer is not familiar with blue albedo in grapefruit. In the past,
he has sent such fruit to various agencies in Florida to find out the causes of
this discoloration and whether or not the fruit is edible. During the past
season, several processors of chilled grapefruit sections were disturbed by blue
albedo in grapefruit received at their plants. Sections from such fruit usually
contain blue streaks which place a question mark on the product. Their first
reaction was to divert this fruit to the juice plant. But since fruit for
sections is generally more expensive than that for juice, either the processor
or the grower would lose financially if this was done. The purpose of this
report is to familiarize the grower and the processor with blue albedo in citrus
fruit and to present some observations and results assembled during the past
years.

Until recently in California, blue albedo in grapefruit has been associated
with the stubborn disease caused by a virus (1). There such fruit is generally
acorn-shaped, small, hard and contains blue albedo. Mature navel oranges with
blue albedo tend to be sour and bitter at the blossom end (2). Recently
Carpenter and Hield (3) found that 2, 4, 5-T sprays on grapefruit trees resulted
in increased incidence of blue albedo in Marsh fruit affected with the stubborn
disease. Up to this time blue albedo had not been associated with any physio-
logical disturbance in citrus. In Florida, Lundberg (4) found that high amounts
of salt applied to the soil induced blue albedo in grapefruit. Also, blue
albedo has been found in Arizona, Texas and Florida.

In Florida blue albedo has been observed in Marsh, Duncan, Foster Pink,
Ruby Red, Burgundy, Thompson Pink and Triumph grapefruit, Valencia orange and
the Orlando tangelo. Blue albedo occurs in the late rather than in the early
stages of maturity of the fruit. It generally appears from March to June in
the regular bloom fruit, but may also occur in June bloom fruit. None has been
observed in immature fruit. Grapefruit grown on rough lemon or sour orange
rootstocks or on young or old trees may be affected. Although not very ex-
tensive, blue albedo may be more prevalent in some seasons than in others. For
example, in one grove during the 1959-60 season, the entire crop of 40,000 boxes
of seedy grapefruit contained blue albedo.

Several degrees of blue albedo have been observed. Sometimes the vascular
bundles and segment walls are colored, with little or no color in the albedo.
In another variation, besides the blue bundles, a narrow ring of blue color is
present in the albedo. This ring may be next to the section membrane or may be
located in the center of the albedo. In still another, the blue color may be
diffused throughout the entire albedo accompanied by color in the bundles. The
blue color may appear in traces in the albedo; however, in several cases it has
been observed +that the albedo was predominantly colored and that even the juice
sacs may sometime appear blue.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
991 9/21/60 EJD









Growers associate blue albedo with many factors, such as virus, excessive
rainfall, freeze, arsenic sprays and over-ripened fruit. However, most cases
occur on sites having a fluctuating water table and poor drainage resulting in
a damaged root system. For example, during the past season, the water table in
a low spot of an old Marsh grove rose from 8 feet to 1 1/2 feet from the surface.
Fruit with blue albedo was found on these trees but up the slope where the vari-
ation in the water table was less pronounced, trees had seven times more roots
than the affected trees and produced normal fruit. In another grove on flat,
shallow land, standing water was a serious problem. Here most of the grapefruit
and some Valencia oranges contained blue albedo. In another area of this grove
that was higher with no surface water problems, none of the fruit examined con-
tained blue color.

Another observation indicates the effect of excessive fertilization or salt
effect on shallow, light soils which may cause some degree of root damage. In a
Valencia grove 4 years old, some trees were located at the bottom of a slope.
These trees had thin canopies, small leaves and small crop. The rest of the
trees in the grove looked normal. The caretaker fertilized the trees four times
during the season, applying a total of two pounds of nitrogen per tree. The
owner, noting the poor condition of the trees at the bottom of the slope, applied
additional top dresser. When the fruit was picked in April, its albedo was
highly colored with even the adjacent flesh having a deep blue color, whereas
the normal trees on the slope produced fruit without color in the albedo.

Blue albedo was found one year in Valencia fruit grown in a potash experimental
grove conducted since 1939. In June, 1957, 5% of the oranges from the no
potash plots were found affected, yet no discoloration was found in the fruit
from trees receiving potash in amounts ranging up to four pounds per tree.

Since blue albedo is associated with maturity, it appears that arsenic
might have some effect. However, in a mature Marsh grove the incidence of blue
albedo in ripe fruit was inversely related to the concentration of the lead
arsenate in the spray (Table 1). Borax used in conjunction with arsenation re-
sulted in no significant increase in blue albedo (Table 1).


Table 1. Effect of lead arsenate and borax sprays on blue albedo in Marsh
grapefruit during 1957
Lead arsenate Blue albedo Also Blue albedo
lb./100 gal. fruit Borax fruit
% lb./100 gal. %

None 41.5 None 22.7
0.4 31.6 1 28.5
1.2 18.9
3.0 10.5
n.s.

Signific.--:t at 5%
n.s. Not significant
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred Florida.
991 a 9/21/60 EJD







-3-


Internal quality in Valencia oranges with blue albedo was affected markedly.
The acid was lowered considerably, but the solids content was less affected.
The acid approximated one-half that of the normal and the Brix was lowered by
one-sixth (Table 2). The ratio, reflecting the change in acid, was raised by
one-half of that in normal fruit.


Table 2. Internal quality of normal and affected Valencia oranges harvested
in April, 1957

Ratio
Blue Brix Acid-% Brix/Acid
albedo Average Range Average Range Average Range

With 9.9 8.5-12.2 .44 .34- .55 22.6 18.9-25.7
Without 11.9 9.7-13.6 .80 .58-1.11 15.3 11.2-19.2



Significant at 1%


What is the material responsible for the blue color in affected fruit?
Preliminary tests indicate that it is an anthocyanin or a similar pigment. Some
of its physical properties, such as its solubility, its turning pink in acids
and others, are similar to those of anthocyanins.

Under storage conditions the color in the fresh grapefruit did not fade
either during storage at 700 F. for four weeks or at 400 F. for 3 months.

The blue color gradually faded from chilled sections prepared from affected
grapefruit when packed in 420 Brix sirup and stored at 400F. After two weeks
the color was still noticeable, but completely disappeared after three weeks. In
sections heated (5) in cans, all traces of color disappeared after six days.

In summary, three degrees of blue albedo in grapefruit have been described.
Observations on the possible causes of blue albedo have also been presented.
Arsenic spray lowers the incidence of blue albedo significantly. Fruit quality
in Valencia oranges was affected markedly. The acid content in the affected
fruit was lowered by one-half and the solids content by one-sixth. Maturity
was advanced since ratio of soluble solids to acid was raised considerably.
Affected fresh fruit when stored at 400 F. and 700 F. did not lose its blue
color. In chilled grapefruit sections with blue albedo stored at 400F., the
color faded after three weeks, but canned sections cleared after six days.






Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
991 b 9/21/60 ED









Literature Cited


1. Fawcett, H. S., J. C. Perry, and J. C. Johnston. The stubborn disease of
citrus. Calif. Citrograph 29: No. 6, 146-147, April, 1944.

2. Fawcett, H. S. Stubborn disease of citrus, a virosis. Phytopath. 16:
675-677, 1946.

3. Carpenter, J. B. and H. Z. Hield. Accentuation of blue albedo in Marsh
grapefruit by sizing sprays with 2, 4, 5-T. Plant Disease Reporter 42:
63-64, 1958.

4. Lundberg, E. C. Sodium in citrus nutrition. Florida Citrus Experiment
Station, Progress Report, December 3, 1953.

5. Atkins, C. D. and A. H. Rouse. Effect of arsenic spray on the quality of
processed grapefruit sections--with special reference to pectin. Proc.
Fla. State Hort. Soc. 71: 220-223, 1958.





























Florida Citruz Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
991 c 9/21/60 EJD




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