Group Title: Bulletin University of Florida. Agricultural Experiment Station
Title: Some analytical studies of the Persian lime
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 Material Information
Title: Some analytical studies of the Persian lime
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 24 p. : ill. ; 23 cm.
Language: English
Creator: Lynch, S. J ( S. John )
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1942
Copyright Date: 1942
Subject: Lime -- Analysis   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliographical references (p. 24).
Statement of Responsibility: by S.J. Lynch.
General Note: Cover title.
 Record Information
Bibliographic ID: UF00026440
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - AEN5230
oclc - 18230194
alephbibnum - 000924603


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represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
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site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida

*7 '

Bulletin 368 February, 1942






Single copies free to Florida residents upon request to

John J. Tigert, M. A., LL. D., President H. P. Adair, Chairman, Jacksonville
of the University3 W. M. Palmer. Ocala
Wilmon Newell, D.Sc., Directors R. H. Gore, Fort Lauderdale
Harold Mowry, M. S. A., Asst. Dir., N. B. Jordan, Quincy
Research T. T. Scott, Live Oak
W. M. Fifield, M. S., Asst. Dir., Admn. J. T. Diamond, Secretary, Tallahassee
J. Francis Cooper, M. S. A., Editors
Clyde Beale, A.B.J., Assistant Editor' BRANCH STATIONS
Jefferson Thomas, Assistant Editors NORTH FLORIDA STATION, QUINCY
Ida Keeling Cresap, Librarian J. D. Warner, M.S. Agron. in Charge
Ruby Newhall, Administrative Managers R. R. Kinkaid, Ph.D., Asso. Plant Path.
K. H. Graham, Business Managert R. W. Wallace, B.S., Asso. Agron.
Rachel McQuarrie, Accountant Elliott Whitehurst, B.S.A., Assistant An.
Jesse Reeves, Asst. Agron., Tobacco
E. St AGRONOnMY W. H. Chapman M.S., Asst. Agron.
W. E. Stokes, M.S., Agronomist,
W. A. Leukel, Ph.D., Agronomists CITRUS STATION, LAKE ALFRED
Fred H. Hull, Ph.D., Agronomist A. F. Camp, Ph.D.. Horticulturist in Chg.
G. E. Ritchey, M.S., Associates Chas. K. Clark, Ph.D., Chemist
W. A. Carver, Ph. D., Associate V. C. Jamison, Ph.D., Soils Chemist
Roy E. Blaser, M.S., Associate B. R. Fudge, Ph.D., Associate Chemist
G. B. Killinger, Ph.D., Associate W. L. Thompson, B.S., Associate Ento.
John P. Camp, M.S., Assistant F. F. Cowart, Ph.D., Asso. Horticulturist
Fred A. Clark, B.S.A., Assistant W. W. Lawless, B.S., Asst. Horticulturist
ANIMAL INDUSTRY R. K. Voorhees, Ph.D., Asso. Plant Path.
A. L. Shealy, D.V.M., An. Industrialist',s T. W. Young, Ph.D., Asso. Hort., Coastal
R. B. Becker, Ph.D., Dairy Husbandman' EVERGLADES STA., BELLE GLADE
E. L. Fouts, Ph.D., Dairy Technologist' J. R. Neller, Ph.D., Biochemist in Chg.
D. A. Sanders, D.V.M., Veterinarian J. W. Wilson, Sc.D., Entomologist
M. W. Emmel, D.V.M., Veterinarians F. D. Stevens, B.S., Sugarcane Agron.
L. E. Swanson, D.V.M., Parasitologist Thomas Bregger, Ph.D., Sugarcane
N. R. Mehrhof, M.Agr., Poultry Husb.s Physiologist
W. M. Neal, Ph.D., Asso. in An. Nutrition G. R. Townsend, Ph.D., Plant Pathologist
T. R. Freeman, Ph.D., Asso. in Dairy Mfg. R. W. Kidder, M.S., Asst. An. Husb.
R. S. Glascock, Ph.D., Asso. An. Husb. W. T. Forsee, Ph.D., Asso. Chemist
D. J. Smith, B.S.A., Asst An. Husb.s B. S. Clayton, B.S.C.E., Drainage Eng.2
P. T. Dix Arnold, M.S.A., Asst. Dairy F. S. Andrews, Ph. D., Asso Truck Hort.'
Husbandmans Roy A. Bair, Ph.D., Asst. Agron.
L. L. Rusoff, Ph.D., Asst. in An. Nutr. Roy A Bair Asst Agron
L. E. Mull, M.S., Asst. in Dairy Tech. SUB-TROPICAL STA., HOMESTEAD
O. K. Moore, M.S., Asst. Poultry Husb. Geo. D. Ruehle, Ph.D., Plant Pathologist
C. V. Noble, Ph.D., Agr. Economists, S. J. Lynch., B.S.A., Asst. Horticulturist
Zach Savage, M.S.A., Associate E. M. Andersen, Ph.D., Asst. Hort.
A. H. Spurlock, M.S.A., Associate W. CENT. FLA. STA., BROOKSVILLE
Max E. Brunk, M.S., Assistant W. F. Ward, M.S., Asst. An. Husband-
ECONOMICS, HOME man in Charges
Ouida D. Abbott, Ph.D., Home Econ.'
Ruth Overstreet, R.N., Assistant RANGE CATTLE STA., ONA
R. B. French, Ph.D., Asso. Chemist W. G. Kirk, Ph. D., An. Husb. in Charge
ENTOMO Y E. M. Hodges, Ph.D., Asso. Agron.
J. R. Watson TOAMO Enmologist Gilbert A. Tucker, B.S.A. Asst. An. Husb.
A. N. Tissot, Ph.D., Associate FIELD STATIONS
H. E. Bratley, M.S.A., Assistant FIELD STATIONS
G. H. Blackmon, MS.A., Horticulturistx M. N. Walker, Ph.D., Plant Pathologist
A. L. Stahl, Ph.D., Associate in Charge
F. S. Jamison, Ph.D., Truck Hort.' K.W. Loucks, M.S., Asst. Plant Path.
R. J. Wilmot, M.S.A., Asst. Hort. Plant City
R. D. Dickey, M.S.A., Asst. Horticulturist A. N. Brooks, Ph.D., Plant Pathologist
3. Carlton Cain, B.S.A., Asst. Hort.4
Victor F. Nettles, M.S.A., Asst. Hort. Hastings
F. S. Lagasse, Ph.D., Asso. Horticulturist. A H. Eddins, Ph.D., Plant Pathologist
H. M. Sell, Ph.D., Asso. Horticulturist' E. N. McCubbin, Ph.D., Asso. Truck
W. B. Tisdale, Ph.D., Plant Pathologist., A. M. Phillips, B.S., Asst. Entomologist'
George F. Weber, Ph.D., Plant Path A hi. Entomologist
L. O. Gratz, Ph.D., Plant Pathologist Bradenton
Erdman West, M.S., Mycologist Jos. R. Beckenbach, Ph.D.. Truck Horti-
Lillian E. Arnold, M.S., Asst. Botanist culturist in Charge
SOILS David G. Kelbert, Asst. Plant Pathologist
R. V. Allison, Ph.D., Chemist,s Sanford
Gaylord M. Volk, M.S., Chemist R. W. Ruprecht, Ph.D., Chemist in
F. B. Smith, Ph.D., Microbiologists Charge, Celery Investigations
C. E. Bell, Ph.D., Associate Chemist W. B. Shippy, Ph.D., Asso. Plant Path.
J. Russell Henderson, M.S.A., Associate' Lakeland
L. H. Rogers, Ph.D., Asso. Biochemist E. S. Ellison, Meteorologists
H. W. Winsor, B.S.A., Assistant Chemist
Richard A. Carrigan, B.S.. Asst. Chemist 'Head of Department
Geo. D. Thornton, M.S., Asst. Chemist 2In cooperation with U. S.
"R. E. Caldwell, M.S.A., Soil Surveyor 'Cooperative. other divisions. U. of F.
Olaf C. Olson, B.S., Soil Surveyor 40n leave for military service.

Gift of IAtUUig olno



EXTRACTORS FOR LABORATORY ANALYSES.._- -....-..-.....-- --.... --.. .. 4
Precision of the Extractors...-..__ ----.....--------..---..--.-.... 4
Efficiency of the Extractors...--- .....- -------------..-- .. --.... -.. 5
METHODS OF ANALYSES_.-_..--....-------.--..-......-------..-- 7
Juice, Acid and Soluble Solids ....---..--------------------...------ 8
'Ricing' of Juice Sacs .--...... ......------------------.... -----. 10
THEIR JUICE CONTENT.--------..- --.-------.... ---------....... ---------.--. 11
MATURITY STUDIES -.....-- ......---. ........-----------..------ ........-------------.. 12
Preliminary Fruit Maturity Tests During 1938 Season .--------.. ... --- ------ 13
Variation in Maturity of Fruit from Trees of Different Ages .._.--- -- 15
Fruit Maturity Investigations of 1939 and 1940 -------. ---..-.... ....... 15
Variation in Maturity of Fruit from Trees Grown on
Different Rootstocks ----.------------.. ... ---..... -------.. -- 16
TOP GRADE LIMES- _...-- ..-.--- -----............. .. -. 20
SUMMARY .--....----. ----..- ....------..- -....------------- 22
LITERATURE CITED .......----------......... .......------------------- --- --------........... ... ..----. 24
The planting of Persian lime trees in Florida has expanded
considerably in the past decade. A partial survey made in the
Redlands fruit growing area of Dade County in April 1938 by
Wolfe (9)2 of 1,200 acres of lime plantings indicates that 85 per-
cent of the plantings have been made since 1933. The survey
was completed later in that year, showing a total of 1,505 acres,
but the percentage of the total planted in any given year was
practically the same as reported in the incomplete survey by
During this period of rapid expansion, and particularly in
the last few years, a number of questions have arisen in connec-
tion with the Persian lime fruit and some of its characteristics.
These were answered from time to time by a series of analyses,
or a small experiment, as the particular subject warranted. The
larger plantings of four and five years ago are coming into heavier
production along with the increased production from the num-
erous topworked orange, tangerine and grapefruit trees in
the central part of the state." This should give a decided increase
each year for several years to come in the quantity of limes
picked for the market. The increase in production is causing an
increased demand for reliable information about the Persian
lime, and to meet this demand the results of a number of investi-
gations have been compiled into this bulletin.
lCitrus aurantifolia Swingle. Also known as the Tahiti lime.
"Italic figures in parentheses refer to "LITERATURE CITED" in the
back of this bulletin.
"It is estimated from fruit shipments that there is about the same
acreage of lime trees, including both young groves and topworks, in the
central portion of the state as in Dade County.

4 Florida Agricultural Experiment Station

Numerous types of extractors are available for the removal of
juice from acid fruits. Many of these types employ equipment of
such size, and require so large a quantity of fruit, that they
are impractical for the laboratory, home or drink counter. Many
require peeled fruit which makes them impractical for tests re-
quiring extensive samplings (6). For laboratory work, and
especially in a routine analysis in which it is desired to determ-
ine the percent juice of a lime or lemon, a reasonably fast, ac-
curate and economical method is desirable. Three types of
extractors, the hand reamer, power reamer and hand press (Fig.
1) are economical to operate, light in weight, handle fruit by in-
dividual halves, remove a very high percentage of the juice and
seem to remove very little of the rind oil.
The precision of a juice extractor can be considered as the
degree of uniformity of volumes of juice removed by the extrac-
tor from each of a series of similar fruit samples. The precision

Fig. 1.-Three types of juice extractors. Left to right, hand reamer,
hand press and power reamer.

Some Analytical Studies of the Persian Lime 5

of the three types of juice extractors was tested by observing the
variations from the mean of pairs of identical samples. An insig-
nificant difference in percent juice content by weight' between
the blossom half and the stem half of Persian lime fruits was
indicated in a series of preliminary analyses. The average juice
content of the blossom half of 120 Persian limes divided into 20
fruit samples was 51.4 .74,5 and of the stem half of the same
fruits 50.5 .83 percent. To obtain two fruit samples of 20 half
fruit each, the blossom halves of 10 fruits were added to the stem
halves of 10 other fruits as one sample and the stem halves of the
former 10 fruits were added to the blossom halves of the latter
10 fruits as the companion sample. All fruits were of approxi-
mately the same size and maturity from trees budded on rough
lemon rootstock.
Table 1 shows a comparison of the precision of the three
types of juice extractors. The error between paired samples is

"The term 'juice content' as hereafter used means percent juice
based on the total weight of fruit.
"The figures in the bulletin representing means are in some in-
stances followed by the sign and more figures. This value is the
probable error of the mean and gives the range within which the
chances are even that the true mean is found.
No. Halves Percent Juice by Weight
per Sample Sample A Sample B Error1
With Hand Reamer
20 43.3 44.3 2.28
20 46.3 46.6 0.65
20 38.9 40.6 4.28
20 40.3 39.5 2.01
20 40.9 41.1 0.49
Average error 1.94 0.46
With Hand Press
20 48.4 48.5 0.21
20 45.8 46.2 0.43
20 49.2 50.5 1.30
20 49.3 48.2 1.13
20 49.0 49.9 0.91
Average error 0.80 0.12
With Power Reamer
20 47.7 47.2 1.05
20 44.2 44.5 0.68
20 48.1 47.2 1.89
20 47.6 47.9 0.63
20 47.4 45.4 4.31
Average error 1.71 0.42
1The figure for error is arrived at by dividing the difference between
juice content of Samples A and B by the mean juice content of the two

6 Florida Agricultural Experiment Station

not excessive for any of the samplings except in one pair using
the hand reamer and one pair using the power reamer. The
hand press, in this series of samplings, showed significantly less
variation between paired samples than did either the hand reamer
or the power reamer. The latter two were of about the same
degree of precision.

The efficiency or percentage of the total juice removed by
an extractor is important. It is also important to know the de-
gree of efficiency one type of extractor possesses in comparison
with another. This latter makes it possible to compare data in-
volving juice content with a truer perspective than when this
differential factor is not taken into consideration. Table 2 is a
comparison of juice removal from paired samples of Persian limes
as extracted by the hand press and power reamer, the hand
reamer and power reamer. The samples were prepared and
paired as in the above tests for precision. The efficiency of the
hand reamer and hand press are calculated on the basis of 100
percent as percentage of the efficiency of the power reamer. The
power reamer does not remove 100 percent of the juice, but, as it


No. Halves Percent Juice by Weight Efficiency
per Sample Power Reamer Hand Press of Hand Press
20 54.7 49.8 91.0
20 53.7 46.7 87.0
20 58.1 49.8 85.7
20 56.4 49.4 87.6
20 57.1 46.4 81.3
Average relative efficiency 86.5 1.04
Percent Juice by Weight Efficiency
Power Reamer Hand Reamer of Hand Reamer

20 50.9 43.7 85.9
20 51.1 41.9 82.0
20 52.2 43.4 83.1
20 51.8 44.4 85.7
20 51.4 39.8 77.4
Average relative efficiency 82.8 0.94
1Efficiency was arrived at by considering the percent juice re-
moved by the power reamer as 100 and expressing comparatively the
juice removed by the other extractors as relative percentages of this

Some Analytical Studies of the Persian Lime 7

removes a much greater percentage than the other extractors, in
this case it is used as a standard. The percentage efficiency of the
individual samples varies widely both for the hand press and for
the hand reamer. This can be accounted for only in part by the
error due to lack of precision of the extractors. The average
efficiency of the hand press is significantly higher than the rela-
tive average efficiency of the hand reamer. Neither the hand
reamer nor the hand press approaches the efficiency of the power
reamer in juice removal. The efficiency in juice removal, the
facility of operation and the speed with which samples can be
handled by the power reamer make it the best of the three types
tested for laboratory juice extraction.
The hand press, of a type shown in Fig. 1, would be desirable
for juice extraction in the grove or packinghouse. It does not
require electric current, is inexpensive, light to carry, easy to
operate under trying conditions and will remove relative percent-
ages of juice from each fruit. Because the hand press is not
highly efficient in juice removal, the relative efficiency of any
particular model should be established, using as a standard the
juice removal efficiency of the power reamer. This will make
possible a more accurate comparison between field and laboratory
Methods of analyses of the Association of Official Agricul-
tural Chemists (1) were used.
Juice Content.-The total weight of the sample was recorded
in grams. In most instances more than one fruit or a single por-
tion of a fruit were considered a sample, and in these instances
the aggregate was treated as an individual sample. The juice
was removed from the cut halves with the power reamer and
strained through a 15-mesh wire sieve. The volume of the
juice was recorded in milliliters. Specific gravity of the juice
was obtained by conversion (5) of degrees Brix of the juice with
correction for temperature. The juice content was calculated as
percentage by weight of the sample of fresh fruit.
Acid.-The acid was determined as the total free acid by
titration against tenth normal sodium hydroxide using phen-
olphthalein as an indicator. It is expressed in the tables as
anhydrous citric acid calculated as percentage by weight of the
extracted juice.

8 Florida Agricultural Experiment Station

Soluble Solids.-The soluble solids were taken on the ex-
tracted juice, from which broken juice sacs and air bubbles were
decanted after standing 15 minutes, with a hydrometer calibrated
in degrees Brix. It is expressed as degrees Brix corrected for

Persian limes when picked from the tree and allowed to
stand at ordinary room temperature have a tendency to lose their
bright luster and turgidity. After 10 to 15 days they tend to
take on a wrinkled appearance. To study the changes taking
place in the juice content, percent acid and percent soluble
solids of Persian limes during the first two weeks after being
picked from the trees, a series of analyses was conducted. The
fruit was picked from trees grafted on rough lemon rootstock.
The maturity as judged from the external appearance of the
fruit was uniform and all fruit were of about the same size.
Seven lots of 20 fruit each were weighed, placed in separate four-
quart baskets and stored at room temperature. The average
daily mean temperature at the Experiment Station during the
period from July 12 to July 24, 1938, was 78.50 F. Room temper-
ature during this period approximated the outdoor temperature.
The first lot of 20 fruit was analyzed on the day of picking.
The other six lots were weighed and analyzed, one lot after each
two-day interval. Determinations were made of the juice con-
tent, percent acid and percent soluble solids.
The data in Table 3 show that the loss in weight of the
stored samples increased directly with the length of the storage
period. The juice content, based on weight of the fruit at time of
sampling, exhibited an increase which became larger as the
fruit remained longer in storage. However, when the percent-
age of juice was based on the weight of the fruit on the day
picked there was no appreciable increase or decrease, as the
percent of juice remained fairly constant for all samples. There
was probably an increase in the percentage of available juice
removed by the reamer from the fruits as their time in storage
lengthened. This could be due to the removal of more unbrok-
en juice sacs by the reamer from fresh picked fruit than would
be removed from fruits after a storage period when the juice sac

Some Analytical Studies of the Persian Lime 9

walls are more easily ruptured. The unbroken juice sacs would
be caught on the sieve and although pressed by hand to remove
most of the juice some would be discarded, their juice content
being lost for the determination. The loss of weight of the fruit
during the storage period was apparently partly from the juice
sacs and partly from the peel and other fruit tissues.


Percent Juice
Based on
No. of Days from Percent Based on Weight at Percent Degrees
Fruit in Picking to Loss of Original Time of Acid Brix
Sample Sampling Weight Weight Sampling
20 0 56.0 56.0 9.4
20 2 2.03 54.0 55.1 5.45 9.1
20 4 4.20 55.3 57.7 5.44 9.2
20 6 5.71 53.4 56.4 5.44 9.4
20 8 7.51 55.3 59.7 5.57 9.5
20 10 10.29 54.3 60.6 5.48 9.9
20 13 12.36 55.5 62.9 5.60 9.6

The acid content remained constant during the storage per-
iod as did also the solids-to-acid ratio. Since the principal ingred-
ients of the juice, namely, acid, soluble solids and moisture, re-
mained constant, and ade made from the juice at each sampling
was of good flavor, it can be considered that there were no de-
leterious effects on the juice of the limes over this short storage

P ...: 1. 1 [T ..- 'It i ..". ', ., !

Fig. 2.-Severe ricing, left, and slight ricing, center, compared with
no ricing, right. Persian lime fruits cut transversely and squeezed
lightly by hand.

10 Florida Agricultural Experiment Station

An undesirable feature exhibited by all immature and some
mature Persian lime fruits, when cut transversely and squeezed,
is "ricing" (Fig. 2). The juice sacs, especially those near the cut
surface, fail to break upon squeezing of the fruit, but, instead,
are forced outward to a position almost vertical to the cut sur-
face, giving the appearance of so many attached grains of rice.
Gaddum (3) and numerous workers quoted by him demonstrated
that there is a change in the pectic compounds during the growth
period found in the locular and juice sac walls making up the
pulp of oranges, lemons, grapefruit and kumquats. Gaddum (3)
further states, citing from Sucharipa (8), that "protopectins,
which are the water insoluble, acid hydrolyzable parent sub-
stances of the pectins, are present in the cell-walls of plants, pos-
sibly in combination with cellulose. Normal ripening processes
are accompanied by a gradual transition from the insoluble pro-
topectins to the soluble pectins with a consequent decrease in
cell-wall rigidity." The findings of these workers would indi-
cate that one of the possible causes of ricing was the rigidity and
toughness of the cell walls of the juice sacs, especially in im-
mature fruit.
Observations indicate that immature Persian limes inva-
riably show ricing, whereas fully mature fruit showing some yel-
low coloring in the peel exhibit this property to such a small de-
gree as to be negligible. However, fruits 125 to 160 days of age
(a large portion of the limes picked are in this age class) are
quite variable in the amount of ricing exhibited. The amount of
ricing at each sampling date was noted in the above described
storage test. A moderate amount of ricing was general for all
fruits on the day of picking, although there was considerable
difference between fruits. Two days after picking the skin of
the fruit had begun to soften somewhat and the degree of racing
was about half as great as that exhibited by the fresh fruit.
There seemed to be a gradual decrease in amount of ricing on
subsequent sampling dates until the tenth day after picking,
when ricing had practically disappeared. The skin of the fruit at
this time was quite soft and wrinkling was noticeable.
The loss of moisture by some of the tissues of the fruit,
probably including the cells making up the walls of the juice
sacs, would effect a general loss of turgidity in the fruit. During
the maturing and ripening processes of the fruit the protopectins

Some Analytical Studies of the Persian Lime 11

are gradually changed over to the pectins with a consequent de-
crease in wall rigidity. Ricing in the fruit would tend to diminish
under the influence of either or both of the above-mentioned
causes. Thus, to satisfy the market demands for limes with easily
extractable juice, fruit that is approaching maturity and has gone
through some curing process such as storage, might well be the

The specific gravity of whole lime fruits can be determined
easily without affecting their salability, either by volume dis-
placement of the fruit in some liquid or by weighing under water.
If the juice content of fruit could be correlated directly with the
specific gravity of the fruit, a very simple means of grading
limes into their respective ranges of juicensss would result.
Toward this end determinations were made on groups of fruit
in May and in November 1937 to establish either a negative or
positive correlation between juice content and specific gravity.
Wolfe (9), in reporting the group of determinations listed below,
stated that "except in rare cases of very dry or pithy fruit, no
correlation showed between juiciness and specific gravity."
The specific gravity of the individual fruit was determined
by weighing in air and under water. The fruit was then cut in
half and the juice extracted by the hand press. The fruits tested
were chosen at random from commercial pickings before the
fruit had been graded at the packinghouse.
Statistical analysis (6) of the data of Table 4 indicates that
there is no correlation between percent juice and specific gravity
of the whole fruit of the Persian lime. The average juice content
is higher for the fruit with a specific gravity above .990 than for
those with a lower specific gravity, but there are too many wide
variations from this average in each category to make this
method of grading lime fruits worthy of consideration.
It was noted, in a few instances, that extremely dry or pithy
fruit had an abnormally low specific gravity.
The variation of specific gravity among fruit with approxi-
mately the same juice content may be due in part to the hollow
core, and cores of varying diameter which are found among the
limes. The considerable difference in rind thickness found
among fruit, even from the same tree, undoubtedly plays a part
in the variation in specific gravity of the fruits.

12 Florida Agricultural Experiment Station

In the light of these observations and tests it does not seem
plausible to consider specific gravity of the whole fruit as a cri-
terion of juiciness.


Sampled 5/10/37 Sampled 11/15/37
Specific Percent Juice Specific Percent Juice
Gravity by Weight Gravity by Weight
.930 43.1 .971 49.8
.954 51.7 .973 51.4
.955 39.7 .975 42.1
.956 45.2 .977 45.7
.963 50.9 .979 48.8
.969 53.2 .980 53.0
.975 47.5 .982 40.1
.978 50.2 .982 49.0
.979 54.4 .984 56.7
.980 47.3 .984 30.5
.984 49.3 .988 54.3
.985 51.0 .989 51.3
.986 51.2 .989 57.6
.987 50.3 .990 49.6
.989 49.1 .991 51.4
.989 49.5 .993 54.3
.990 50.3 .993 48.5
.991 46.1 .994 54.1
.992 48.8 .995 49.0
.998 51.4 .995 55.8
1.000 49.0 .995 54.6
.995 48.4
.997 52.9
.998 55.1
.998 54.8
.999 74.9
.999 47.2
.999 48.6
1.000 55.2
1.002 57.0
1.003 50.2
1.003 52.9
1.008 54.4
1.009 50.5

A problem which confronts the grower and shipper of Persian
limes is determining at what stage in the maturity of the fruit it
possesses the optimum juice and acid content. As a step toward
answering this question, a limited analytical study was made of
Persian limes at progressive stages of maturity for three seasons.
During the 1938 season fruits of approximate known age
were tested from trees of different ages, all trees grafted on
rough lemon rootstock. An extremely heavy drop of tagged

Some Analytical Studies of the Persian Lime 13

fruit reduced considerably the number of fruit available for
sampling. The trees used in this test received no irrigation. As
there were several periods throughout the season when the trees
were suffering from drought, as indicated by leaf curl and slight
loss of turgor of the fruit, it is probable that the fruits did not
make their maximum growth. Furr and Taylor (2), working in
California, found that the final size of lemons was decreased
markedly in plots which were irrigated only when the leaves
began to roll, as compared to plots in which water was applied at
such short intervals that the trees showed little or no water
In the 1939 season the samples were taken from trees eight
years of age, grafted on five different rootstocks-willowleaf sour
orange, rough lemon, sour orange, bittersweet orange and Cleo-
patra. In the 1940 season samples were taken from trees nine
years of age, grafted on these five rootstocks and, in addition,
from nine-year-old trees grafted on grapefruit rootstock. These
trees were irrigated when evidence of drought was apparent but
a heavy drop of tagged fruit was again experienced in 1939 and
also in 1940.

The fruit for these preliminary tests was taken from trees
of three different ages, four years, seven years, and 11 years,
grafted on rough lemon rootstocks. Fruits from trees of each age
were tested separately. The fruits selected for tagging (a white
paperboard tag was attached to the pedicel of each fruit) were 41
mm. in diameter, as the bloom and fruit of smaller size were too
scarce to allow tagging of sufficient fruits for analyses. In com-
parison of size with fruit from tagged blossoms, the 41 mm. fruit
were estimated to be approximately 75 days from blossoming.
The size of the fruit at tagging was determined with a wire ring.
Sampling began on an estimated 110 days from blossoming
and was continued at approximately two-week intervals there-
after until the fruits began to turn yellow. Ten fruits were taken
as a sample from both the seven-year-old and 11-year-old trees.
The 10-fruit sample from the four-year-old trees was selected in
part from each of three trees. The fruits were analyzed individ-
ually by the usual methods. The diameter of the fruit was taken
with calipers at the place of greatest transverse section.


Date Tree Age of Weight in Grams Diameter Percent Juice Percent Degrees
fruit Max. Min. Avg. Max. Min. Avg. Max. Min. Avg. Acid Brix
6/20/38 4-year old 110 days 80.4 55.2 66.9 51 46 48 54.2 45.3 50.2 5.63 10.2 Q
7/7/38 127 101.7 63.5 81.3 56 48 52 58.6 45.0 51.8 5.53 9.8 :
7/18/38 138 126.8 68.3 90.3 60 49 54 60.1 51.6 55.6 5.56 9.4
8/2/38 153 125.8 80.9 100.3 66 50 56 63.2 50.1 55.0 5.58 9.0
8/16/38* 167 143.7 98.8 115.8 63 55 59 61.4 38.9 54.2 5.92 9.5 .
6/20/38 7-year old 110 days 76.3 55.3 68.2 45 51 48 56.0 45.5 51.1 5.14 9.6
7/7/38 127 101.2 76.0 85.9 57 50 53 56.1 50.8 53.6 5.30 9.4
7/18/38 138 104.5 73.9 88.1 56 48 53 59.6 43.4 54.0 5.13 9.0
8/2/38 153 120.0 92.1 108.4 59 54 57 63.9 46.2 56.6 5.14 8.6
8/16/38** 167 125.4 100.3 112.0 61 55 58 67.4 55.3 62.5 5.09 8.5
6/20/38 11-year old 110 days 74.3 53.9 62.7 48 44 46 53.6 45.5 50.4 5.20 10.4 S.
7/7/38 127 88.1 63.0 78.1 53 47 51 54.0 45.5 50.2 4.99 10.0
7/18/38 138 97.6 77.6 88.2 56 50 52 57.8 49.4 54.2 5.01 9.2
8/2/38 153 121.2 80.2 95.2 61 52 55 62.6 53.2 55.9 4.94 9.1
8/16/38*** 167 105.5 98.3 101.9 54 54 54 60.0 56.0 58.0 5.07 8.3

* 5 fruit in sample
** 8 fruit in sample
***2 fruit in sample

Some Analytical Studies of the Persian Lime 15

The data of Table 5 show a consistent increase in the average
weight of the fruits from all trees as the age of the fruit in-
creased. The maximum and minimum columns indicate a wide
variation in weight and also diameter among fruits of the same
age. This difference in weight and diameter was evident
throughout the growth period. The average weight and the
average diameter of the fruit from the 11-year-old tree were
slightly but consistently less during the season than those of the
fruit from the four- and seven-year-old trees. This was probably
due to the large crop on the 11-year-old tree, as compared with the
moderate crops on the other trees. It has been observed that
trees with heavy crops tend to produce smaller fruit than trees
with moderate to light crops.
With few exceptions there was a gradual increase in juice
content during the growth period for the fruit from trees of all
ages. Also the juice content was quite similar for the fruit of
the trees of all ages.
The percent acid in the juice from fruit from each age group
remained constant throughout the period of sampling. As the
juice content increased the total amount of acid in the individual
fruit increased also. However, the fruit from the four-year-old
trees contained from 7 to 17 percent more acid per gram of juice
than fruit from the seven- and 11-year-old trees.
The soluble solids declined about 1 degree over the sampling
period in fruit for all of the trees. This value was very similar
for trees of all ages at any one sampling date.
Ade was made from the excess juice at time of sampling. The
juice from all trees at the 110-day sampling had a distinct, bitter
after-taste. At the 127-day sampling the fruit from the four- and
seven-year-old trees made palatable ade, but that from the 11-
year-old trees was slightly bitter. At the 138-day sampling the
ade made from the fruit from the trees of all ages was excellent.
Apparently the fruit reached maturity, as measured by palatabil-
ity, satisfactory juice and acid content, in from 125 to 140 days
from blossom opening.
The fruits for the investigations of 1939 and 1940 were of
known age at each sampling. Ten flower clusters were tagged at
the time of a heavy bloom on the test trees, which occurred in

16 Florida Agricultural Experiment Station

May 1939 and in February 1940. One week later, after the
petals had fallen and the first heavy drop of small fruit had
occurred, small fruits, comparable to the 10 tagged samples, were
tagged. This made it possible to know the age of the fruits at
sampling time to within one or two days of their true age. In
1939 200 small fruits scattered over five trees were tagged on
each rootstock. Twenty-four percent of the tagged fruit was re-
covered for sampling. In the 1940 season 1,000 small fruits were
tagged on the same groups of trees on each rootstock but only 6
percent was recovered for sampling.
Samples of 10 fruits from each rootstock were collected at
114 days of age in 1939 and 100 days of age in 1940, with subse-
quent samples following at about two-week intervals until the
fruit turned yellow or until no more fruit of known age was
Results of these two seasons' investigations are given in
Tables 6 and 7. The figures in Table 6 represent the average
value of 10 fruits which were weighed, measured and juice ex-
tracted as one sample during the 1939 season. The figures in
Table 7 for the 100- and 115-day age samplings were determined
the same way, but the values for the 128-, 142-, 156- and 170-day
old samplings represent the average of 10 fruits weighed, meas-
ured and juice extracted individually. The maximum and mini-
mum values under each category are given. The acid and Brix
values were determined upon the aggregate juice of each
sampling. The data in both tables have been arranged under
each rootstock according to the progressive age of the fruit for
ease of comparison. The weight, diameter and length of the
fruit on all rootstocks, with minor exceptions, increased as the
fruit increased in age. This increase was accelerated during the
first and last two weeks of the sampling period; namely, before
the fruit was 114 to 115 days old and after it reached an age of
154 to 156 days. The maximum and minimum values in Table
7 show the great variation in weight and size between fruit at any
one age. These wide variations were found in fruits on all the
rootstocks tested.
Fruits grown on rough lemon rootstock were of greater
weight and size than those grown on any of the other rootstocks.
This held true throughout the sampling period. Fruits grown on

Some Analytical Studies of the Persian Lime 17


9/29/39 a128 70.1 49 55.6 9.9 5.60
10/12/39 140 78.0 50 60.0 9.9 5.62
10/26/39 154 89.2 55 62.3 9.9 5.81
11/6/39 165 116.3 59 63.0 9.4 5.68
o CM bi- o

9/15/39 Rough lemon 114 72.5 49 49.4 9.2 5.59
9/29/39 128 87.1 52 59.5 8.8 5.47
10/12/39 140 96.1 54 60.4 9.0 5.41
10/26/39 154 120.7 59 59.6 8.6 5.57
9/15/39 Sour orange 114 76.0 50 56.1 10.0 5.86
9/29/39 128 83.7 51 58.4 9.9 5.56
10/12/39 140 85.5 52 63.2 10.1 5.54
10/26/39 154 98.0 55 63.3 9.2 5.54
9/15/39 Bittersweet 114 69.4 48 53.2 9.7 5.43
9/29/39 128 79.1 51 57.9 10.0 5.38
10/12/39 140 94.8 52 61.4 9.9 5.40
10/26/39 154 109.1 57 63.8 9.5 5.41
11/6/39 165 121.8 59 63.5 9.4 5.59
9/15/39 Cleopatra 114 64.6 47 53.1 9.6 5.22
9/29/39 128 74.3 49 60.0 9.5 5.34

10/12/39 140 87.0 51 60.5 9.4 5.59

grapefruit, Cleopatra, bittersweet, sour orange and willowleaf
sour orange stock were similar in weight and size at any particu-
lar age, except in 1939, when those grown on bittersweet were
slightly heavier and larger than fruits from the other four. Fruits
of the same age group were larger and heavier on all rootstocks
in the 1939 tests than in 1940. The difference in fruit size was
due, to a considerable extent, to difference in size of crop. There
was a heavy crop on the trees while the 1940 test fruits were
maturing but only a light crop on the trees while the 1939 test
fruits were maturing. The period from 128 days to 156 days in
the life of the fruit showed the least acceleration in change of
fruit size or weight. It is fruit of this age group that is picked
for shipment. Older fruit, although it increases somewhat in size
and weight, suffers the loss of some of the bright green color,
often turning a greenish yellow to yellow. Stylar-end break-
down is quite prevalent in these lighter colored fruits.

18 Florida Agricultural Experiment Station

The juice content in the fruit increased with maturity. It
was very similar for the fruit from the different rootstocks, with
a few exceptions, at any of the sampling periods. The increase in
juice content was most rapid up to the 128-day age, and was very
gradual from the 128-day to 154-day age. After the 154- to 156-
day period, the juice content, with minor exceptions, became
either stationary or decreased slightly. At the sampling periods
in the 1940 season when the fruits were analyzed individually, a
substantial difference in juice content was found between those
containing the maximum and those containing the minimum per-
centages in a sample'. There was, however, no correlation be-
tween these differences and the age of the fruit or the rootstock
on which grown.
There was generally a higher percentage of juice in the fruits
sampled in 1939 than in those sampled in 1940. This may have
been due in part to the smaller number of fruits on the tree dur-
ing the 1939 season in the heavy summer crop on the
tree while the 1940 samples were taken. Also during the growth
and maturity of the fruits sampled in 1939 rainfall was plentiful,
52.57 inches of rain being recorded for the five months prior to
maturity, whereas in 1940 only 25.60 inches of rain was recorded
during the same comparable period.
The percent acid was not influenced either by the rootstock
or by the age of the fruit as represented in the samples. It is of
interest to note that the percent acid was higher in general dur-
ing 1939, a wet season, than during 1940. The soluble solids in
the juice were not influenced by the rootstock on which the fruit
was grown. The age of the fruit, however, seemed to have a
slight influence. The soluble solids declined about 2 degrees
from the time the fruit was 100 days old until it was 170 days old.
Approximately half of this decrease, as observed during the 1940
season, occurred between the ages of 110 days and 115 days. The
fruits within the 128- to 156-day age group contained, with a few
exceptions, a uniform soluble solids content. The soluble solids
during the 1939 season were slightly lower than during the 1940
These analytical studies with limes indicated that there was
no differential influence upon their juice content, percent acid

"Where the wide differences appeared, they were due in almost every
case to either a single fruit being excessively high or low in juice content,
or to two fruits, one moderately high and one moderately low in juice

4 Weight of Fruit Diameter Length
S(grams) Percent Juice (mm.) (mm.)
Date Rootstock r. o

5/20/40 Willowleaf sour orange 10 100 26.7 --_ 21.7 --- -- 25. ---- 32 _- .... 5.50 12.7
6/4/40 Willowleaf sour orange 10 115 39.1 _-- ---_ 32.0 -- --- 40- 46 -- .... 6.06 10.0
6/17/40 Willowleaf sour orange 10 128 48.5 62.0 37.0 43.0 50.0 37.8 43 47 39 48 54 43 6.09 10.2
7/1/40 Willowleaf sour orange 10 142 51.0 58.0 39.0 45.1 50.0 38.5 44 47 41 49 52 43 5.52 9.9
7/15/40 Willowleaf sour orange 10 156 59.0 78.0 38.0 46.3 50.7 38.2 46 50. 39 51 57 41 5.67 10.2
7/29/40 Willowleaf sour orange 10 170 74.0 123.0 46.0 47.0 53.8 40.7 50 57 44 54 70 44 5.94 10.1
5/20/40 Rough lemon 9 100 39.2 --..-- .. 26.7 -- --- 27 ... 33 5.81 11.9
6/4/40 Rough lemon 10 115 59.8 -- -- 39.0 .--- -. 47 .- -. 51 6.26 10.0
6/17/40 Rough lemon 10 128 64.6 106.0 39.0 41.8 47.2 26.8 47 56 39 52 63 44 5.71 10.0
7/1/40 Rough lemon 10 142 73.0 107.0 51.0 47.8 54.9 43.4 49 57 43 55 62 47 5.58 10.0 -
7/15/40 Rough lemon 10 156 79.0 113.0 57.0 49.6 52.5 46.8 51 59 46 55 62 49 5.79 9.7
7/29/40 Rough lemon 5 170 109.0 127.0 94.0 51.5 53.0 49.7 58 62 55 62 67 57 5.80 9.4
5/20/40 Sour orange 10 100 19.3 ---- .... 16.4 --. --.. 20 --- 27 5.58 13.0
6/4/40 Sour orange 10 115 47.8 -----.. 34.7 _-- -- 43 ----- 49 6.35 11.2
6/17/40 Sour orange 10 128 55.1 70.0 43.0 44.1 46.3 38.6 45 48 43 51 58 44 6.27 11.1
7/1/40 Sour orange 10 142 61.0 88.0 35.0 44.3 48.2 34.3 46 52 39 53 64 42 6.04 10.7
7/15/40 Sour orange 10 156 65.0 82.0 53.0 47.0 50.8 43.1 47 54 42 52 58 48 6.01 10.4
7/29/40 Sour orange 10 170 79.0 97.0 54.0 49.4 54.0 45.5 51 57 44 57 61 55 6.30 10.3
5/20/40 Bittersweet 10 100 26.1 ...- ... 18.1 ----21 ----- 31 5.60 11.7
6/4/40 Bittersweet 10 115 45.4 -_- ---. 34.8 .... -- 42 48 __- 6.09 10.6
6/17/40 Bittersweet 10 128 49.8 61.0 39.0 42.7 47.2 34.1 43 45 39 50 54 48 6.30 10.5
7/1/40 Bittersweet 10 142 60.0 82.0 44.0 43.7 49.4 38.4 46 50 42 51 59 45 5.81 10.1
7/15/40 Bittersweet 10 156 63.0 81.0 53.0 47.7 51.4 43.8 47 52 44 53 60 49 5.94 10.2 '
7/29/40 Bittersweet 8 170 58.0 70.0 52.0 46.3 50.5 37.0 46 50 44 52 56 48 5.71 9.9
5/20/40 Grapefruit 10 100 25.0 .... .... 23.1 ....- .... 21--- ... 32 6.32 12.5
6/4/40 Grapefruit 10 115 50.1 ---- ... 37.3 -- ---.. 43 .... 51 6.48 10.3
6/17/40 Grapefruit 10 128 50.0 69.0 34.0 43.6 48.9 28.9 44 47 39 50 59 44 6.42 10.1
7/1/40 Grapefruit 10 142 65.0 75.0 48.0 45.5 52.0 39.2 47 50 42 54 56 48 6.27 10.1
7/15/40 Grapefruit 1.0 156 58.0 78.0 42.0 45.7 51.3 35.8 46 50 41 50 59 45 6.14 10.5
7/29/40 Grapefruit 8 170 65.0 88.0 51.0 45.6 54.5 45.2 48 54 43 54 59 47 6.03 10.2
5/20/40 Cleopatra 10 100 28.1 ..... 22.6 ...--- 22 --- 32 7.66 14.1
6/4/40 Cleopatra 10 115 52.1 .... _. 34.2 --- .--. 44 ... 51 _ 6.82 11.9
6/17/40 Cleopatra 10 128 59.3 65.0 48.0 42.6 47.4 36.9 46 49 41 54 57 52 6.55 11.1 '
7/1/40 Cleopatra 10 142 67.0 83.0 47.0 44.5 51.3 42.1 47 52 40 55 60 51 6.14 10.6
7/15/40 Cleopatra 10 156 65.0 83.0 50.0 46.7 52.1 33.3 47 52 43 54 59 49 6.03 10.6
7/29/40 Cleopatra 9 170. 77.0 109.0 43.0 45.6 50.9 37.4 50 56 41 57 65 42 5.78 10.2

20 Florida Agricultural Experiment Station

and percent soluble solids by the rootstocks on which they were
grown. However, limes grown on rough lemon rootstock were of
greater weight and size than those grown on any of the other
rootstocks tested. In the light of these observations the selection
of desirable rootstocks for limes should be judged on the produc-
tion of small to medium-sized fruit, heavy bearing habits, resist-
ance to disease and drought, congeniality of the graft union,
adaptability to the soil, and type of tree growth resulting.

The investigation of seasonal variation in juice and acid con-
tent of Persian limes was carried out during the 1938 season (4).
The object of the analyses was to determine the quality, in re-
gard to juice and acid content, of the top grade limes shipped
from the Redland district. The tolerance for defects allowed for
top grade limes were not uniform for the four packinghouses
from which the samples were obtained. However, the top grade
from each of the packinghouses was similar enough in quality to
be considered a single grade for the purposes of this series of
Samples were taken every two weeks, on Monday and Tues-
day,, since these were the heavier picking and shipping days. A
sample consisted of 20 first grade fruits from a packinghouse.
The fruit chosen was of average size for that particular picking.
As many groves were represented by each sample as there were
different lots of fruit in the packinghouse. Since all of the houses
were not shipping every time samples were taken, the total num-
ber of fruits analyzed each time varied from 40 to 80.
The fruits were weighed and the juice was extracted and
measured individually, as previously described. Specific gravity
and percent acid were determined from the aggregate juice of
the fruits from each packinghouse.
The 1938 shipping season for Persian limes from the Red-
land area extended from June through December. During this
period 16 samples were taken at two-week intervals. The weight,
juice content, and percent acid of the fruit from each of the four
packinghouses were quite similar and the data of all four are
combined, for brevity of presentation, into Table 8. The data
under the headings "Average weight of fruit" and "Average per-
cent juice" represent an average of the individual fruits sampled

Some Analytical Studies of the Persian Lime 21

on that day. The data under "Average percent acid" represent
an average of the acid content of the samples taken on that day.
The weight and diameter of the fruit increased as the season
progressed, larger and heavier fruit being picked during Novem-
ber and December. Probably the heavier crops on the trees
during the summer months tended to keep down the size. Also
the tendency of the grower to lighten the heavy crop on the tree
by picking the limes before they had reached a maximum size
accounted for the smaller average size being marketed during the
summer. Both the minimum and maximum weight fruits in a
sample were smaller during the summer months than during the
fall and winter months.
The data show that the average juice content for the season
was consistently 50 percent or better except for one picking in
June and one in December, at which times the juice content fell
a fraction of a percent below 50. There were two periods during
the season when the juice content was highest. The first was
during August and early September, when the average juice
content ranged from 57 to 59 percent, and the other from the
middle of October to the middle of December, with an average
juice content of from 55 to 58 percent. It is of interest to note
here that during the month preceding each of these peaks the
rainfall was excessive. During July there was almost 10 inches
and from September 15 to October 15 there was a little over seven
inches of rainfall. The minimum juice content of an individual
fruit dropped as low as 29.4 percent in one instance, but the mini-
mum average for the season was 40.3 percent. Thus, if even the
driest limes were selected they still contained only about 15 per-
centage points less juice than the average fruit shipped. The maxi-
mum juice content remained about 65 percent with a few minor
exceptions. In all cases the fruits containing the minimum and
those containing the maximum juice content were but a small
portion of any sample.
The average juice content for the entire season was 54.6
percent, the lowest sampling being 49.4 percent and the highest
59.0 percent.
The acid content of the juice averaged 5.65 percent by
weight for the season, with individual samplings varying very
little from this figure.
The quality of the limes in juice content and percent acid
was very satisfactory for the fruit from all packinghouses. The
smaller size of the fruit during the summer months was a de-

22 Florida Agricultural Experiment Station

Weight of Fruit
No. of (Grams) Percent Juice Percent Acid
Date Fruit
Min. Max. Avg. Min. Max. Avg. Avg.
6/14/38 40 59.2 92.5 73.6 42.0 54.9 49.6 5.83
6/28/38 60 53.3 119.6 74.8 37.0 60.4 50.5 5.40
7/12/38 60 54.4 120.0 75.9 47.9 62.0 54.0 5.55
7/25/38 60 61.6 118.9 93.2 40.0 66.0 54.4 5.37
8/9/38 60 65.2 117.9 84.2 42.7 65.5 57.8 5.59
8/23/38 60 59.2 119.3 85.3 33.9 84.8 57.1 5.57
9/2/38 60 69.9 127.4 96.5 46.7 67.7 59.0 5.93
9/20/38 40 53.4 116.2 85.3 29.4 64.8 53.1 5.51
10/4/38 60 63.5 135.1 93.6 37.9 65.3 50.3 5.83
10/18/38 38 60.5 139.1 93.2 46.9 65.5 57.3 5.59
11/1/38 60 59.9 153.4 102.3 38.7 67.8 57.4 5.52
11/15/38 60 74.5 130.0 104.3 38.3 63.2 55.3 5.55
11/29/38 40 70.0 155.2 105.0 45.4 67.3 58.0 5.45
12/13/38 40 77.5 179.0 118.5 45.9 73.5 57.0 5.62
12/28/38 40 66.1 145.4 96.2 38.5 60.6 49.4 6.13
1/10/39 80 61.6 158.0 100.0 33.9 63.7 52.8 5.93
Average 63.1 132.9 92.6 40.3 65.8 54.6 5.65

sirable feature, since the larger sizes command a lower price
during the peak months of the season. The months of heaviest
pickings are from June through September. During the fall,
winter and early spring months, when only small quantities of
fruit are harvested, fruit size has very little effect upon prices.
As there was no correlation between fruit size and juice content,
and as the percent acid remained consistent for the season, a
plausible harvesting program would be one wherein fruit of
smaller size but satisfactory juice content and flavor would be
picked during the summer months; during the months of light
production and less discrimination against large size, the fruit
can be allowed to remain longer on the trees, attain a larger size
and thus increase the yield.
Persian lime fruits from trees grown on five rootstocks were
analyzed over three seasons for variations in juice content, per-
cent acid and percent soluble solids as affected by storage and
maturity, and the relation of juice content to specific gravity of
the fruit as well as seasonal variation of juice and acid content
of top grade limes were studied.
Three types of juice extractors, a power reamer, hand ream-
er and hand press, were tested for efficiency and precision in
juice removal from lime fruits and for adaptability to laboratory

Some Analytical Studies of the Persian Lime 23

The power reamer, due to its efficiency in juice removal,
facility of operation, and speed with which samples can be
handled, was the best type of laboratory juice extractor. The
hand press, of the type tested, was adaptable to juice extraction
in the grove or packinghouse. The hand reamer proved impracti-
cal for either laboratory or field analyses.
Loss in weight by the fruit during a short storage period at
room temperature was apparently partly from juice sacs and
partly from the peel and other fruit tissues. The actual juice con-
tent as removed by the power reamer remained constant. The
degree of ricing of the juice sacs was materially reduced by a
short storage or curing period.
No correlation was found between specific gravity of the
whole lime fruit and its percent juice content by weight.
Fruit analyzed from trees of different ages (4 years, 7 years,
and 11 years), all on rough lemon rootstock, showed wide varia-
tion in weight and size for the same age fruit throughout the
growth period. Juice content increased gradually during the
growth period and was quite similar for the fruit from trees of
different ages. Percent acid in the juice remained constant dur-
ing the growth period, but fruit from the younger trees showed
a greater percentage of acid. Soluble solids of the juice declined
slightly and similarly during the sampling period in fruit from
the trees of the three different ages. The fruit reached maturity,
as measured by palatability and satisfactory juice and acid con-
tents, in from 125 to 140 days from blossoming.
Fruit analyzed from trees grafted on different rootstocks
(rough lemon, grapefruit, Cleopatra, bittersweet, sour orange and
willowleaf sour orange) during the growth period of the fruit
indicated: that fruits grown on rough lemon rootstock were of
greatest weight and size throughout the growth period sampled,
while fruits grown on the other rootstocks were generally of
similar weight and size at any particular age sampled; that there
is a general difference in fruit weight and size in different years;
that the juice content of the fruit increased with maturity and
was similar for the fruit from the different rootstocks at each
sampling period; that after the 154- to 156-day age period, the
juice content became either stationary or decreased slightly; that
the percent acid content of the juice was not influenced either
by the rootstock or by the age of the fruit as represented in the
samples; that soluble solids content of the juice was not in-
fluenced by the rootstocks tested.

24 Florida Agricultural Experiment Station

SVery satisfactory juice and acid content was observed in top
grade limes from four packinghouses throughout the 1938 season.

Grateful acknowledgment is made to the lime growers and packers
of the Redland district for their generous cooperation in furnishing fruit
for many of the analyses. The writer acknowledges also his indebted-
ness to Dr. H. S. Wolfe, iwho initiated some of these studies and for his
helpful advice in conducting some of the analyses, to Dr. G. D. Ruehle
and Mr. W. M. Fifield for helpful criticism, and to Mr. J. T. Hall, Jr., and
Mr. H. I. Mossbarger, Jr, for performing much of the analytical work in
the laboratory.

1. Association of Official Agricultural Chemists. Official and tentative
methods of analyses. 4th ed. 1935.
2. Furr, J. R., and C. A. Taylor. Growth of lemon fruits in relation to
moisture content of the soil. U. S. D. A. Tech. Bul. 640: 1-71. 1939.
3. Gaddum, L. W. The pectic constituents of citrus fruits. Fla. Agr.
Exp. Sta Bul. 268: 1-23. 1934.
4. Lynch, S. J. Seasonal variation in juice and acid content of Persian
limes. Proc. Fla. State Hort. Soc., pages 81-83. 1939.
5. Olsen, J. C. Van Nostrand's chemical annual. D. Van Nostrand
6. Snedecor, G. W. Statistical methods. Collegiate Press, Inc. 1938.
7. Stahl, A. L. Composition of miscellaneous tropical and subtropical
Florida fruits. Fla. Agr. Exp. Sta. Bul. 283: 1-20, 1935.
8. Sucharipa, R. Protopectin and some other constituents of lemon
peel. Jour. Amer. Chem. Soc. 46: 145-156. 1924.
9. Wolfe, H. S.: Fla. Agr. Exp. Sta. Ann. Rept., page 184. 1938.

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