Florida Citrus Processors Association 

1611 Harden Blvd../Lakeland, FL 33803 

Tel.(863)293-4171/ Fax. (863) 683-2849 

April 27, 2011 

Mr. Terry Bane, Branch Chief 

USDA, AMS,FV,PPB 

STOP 0247 

1400 Independence Ave SW 

Washington, DC 20250-0247 

 Subject: United States Standards for Grades of Grapefruit Juice 

Dear Mr. Bane: 

 The Florida Citrus Processors Association (“FCPA”), a leading representative of 

United States processors of grapefruit juice, hereby requests a revision to the United 

States Standards for Grades of Grapefruit Juice (48 FR 40875) and asks that the 

maximum “free and suspended pulp” (referred to in the industry as “sinking pulp”) grade 

parameters be eliminated from the USDA grade standards for all forms of grapefruit 

juice. Currently, the standards provide that Grapefruit Juice from Concentrate, Grapefruit 

Juice and Frozen Concentrated Grapefruit Juice have maximum free and suspended pulp 

as follows: Grade A- 10% by volume; Grade B 15% by volume. Concentrated Grapefruit 

Juice for manufacturing requirements are Grade A- 10% by volume and Grade B-12% by 

volume. 

I. The Reason for the Proposed Revision. 

The existing United States Standards for Grades of Grapefruit Juice, that relate to 

maximum values for free and suspended pulp, do not take into account modern extraction 

and finishing technologies, nor are they supported by evidence of correlation between 

these criteria and acceptable flavor. 

II. Technical Information Supports the Revision. 

The free and suspended pulp parameters have been a part of the USDA Grade Standards 

for Grapefruit Juice since the standards were first issued in 1941. In the evolution of the 

citrus industry, excessive sinking pulp was, early on, perceived as an indication of high 

pressures used in extraction and finishing of citrus juice and bitterness in juice where 

these high extraction pressures were applied. The current standards have been in effect 

since 1983. In the promulgation of the 1983 USDA Grade Standards, it was noted that 

sinking pulp levels could be correlated to bitter flavor (the bitter flavors in grapefruit 
juice are due to the naturally occurring flavanone glycoside, naringin and the liminoid, 

limonin). Although bitterness is an inherent contributor to what we know as “grapefruit 

flavor,” an excessive amount of bitterness can be objectionable to some consumers. 

Processing technologies used in the early 1940’s, while such technologies were in their 

infancy, were considerably different than the technologies in place today. 

We have learned that sinking pulp levels can be greatly influenced by modern processing 

techniques, which techniques eliminate the correlation between sinking pulps, and “hard” 

extraction and finishing results in excessive bitterness. 

Brown International Corporation and John Bean Technology Corp. (formerly FMC) are 

the two predominant suppliers of commercial citrus juice extraction and processing 

equipment in the United States. Equipment changes by these suppliers since the standard 

was first published supply some basis for the requested revision. 

Early FMC juice extractors used press type applications and did not use a pre-finishing 

strainer concept inside the extractor as is the case today. This change to FMC equipment, 

has since 1947, proved to be a significant advancement for citrus juice quality. Other 

quality improvements were also realized by incorporating new finishing technology 

which separates juice and juice solids.

Brown brand juice extractors are designed to extract juice, cell sacs, seeds, and some of 

the membranes from the peel by a combined pressing and wiping action. This gentle 

method leaves a sound extracted peel half, which is not crushed or mangled. Reamed 

juice from a Brown extractor has greater whole cell sac retention and very little bitter 

tasting oils and peel extracts. Reamed juice is free of all albedo (where the largest 

concentrations of naringin reside in the fruit) and flavedo. A significant advantage of the 

reaming method is that numerous undesirable components inherent in the peel are not 

liberated into the juice. Brown equipment currently also uses other finishing technology 

that was not available when the standards were originally adopted. 

There are several more recent processing technologies that have been introduced that 

probably have even more influence in making maximum levels for sinking pulp 

questionable as a factor in determining grapefruit juice quality. The post 

extractor/finisher technologies of centrifugation and homogenization can reduce sinking 

pulp levels dramatically. These technologies can be used for pulp removal (primarily to 

reduce viscosity) to prevent gelation of grapefruit juice concentrate in storage, to allow 

evaporators to produce more highly concentrated juice, to improve flow rates when 

pumping concentrates, and to improve product flow in juice dispensers in convenience 

stores, restaurants, etc. Centrifuges are also used for removing defects in juice. 

 

Centrifuge efficiency in citrus plants is simply calculation of the difference in percent 

pulp between the feed and product streams divided by the percent pulp in the feed stream. 

At normal feed rates, the process tries to achieve 20-50% pulp reduction. If the process 

requires greater than 50% reduction, slower feed rates and loss of capacity will result. It 

2 
should be noted that since centrifuge applications result in juice yield loss, careful control 

and optimization is important.

In other words, juice that leaves the finisher at 16% sinking pulp could be easily reduced 

via centrifugation to achieve 8% sinking pulp in the final pulp testing during grading. The 

16% sinking pulp juice, in this instance, could be high in naringin content, but not 

necessarily so, depending on fruit maturity. Centrifugation can thus render any 

correlation between harsh extraction and sinking pulp levels invalid. 

When centrifugation is used, pulp levels can be reduced leaving the naringin/ limonin 

levels unchanged in the juice. 

 Another way to reduce viscosity is to homogenize or break up particulate matter in the 

juice. This process results in “finer” particles of pulp, which when “spun down” in the 

laboratory centrifuge during the pulp test, will result in more compaction of the pulp and 

yield a lower percent by volume of sinking pulp as a result and without affecting 

naringin/limonin content. 

Also, some processors now use debittering technology to reduce naringin/limonin levels 

for consumer acceptance. This technology leaves pulp levels unchanged while decreasing 

bitterness. This technology utilizes absorption resins to selectively remove limonin and 

naringin. 

Limonin levels as high as 40 ppm can be debittered to as low as the generally accepted 

taste threshold of 7 ppm, depending primarily on the amount of resin used.

In addition to processing enhancements, methods of storage of grapefruit solids have also 

changed through the years providing opportunities to produce products with more 

consistent quality. 

Data collected by John Bean Technologies Corp. of Lakeland, FL (“JBT”) demonstrates 

over several seasons that there is no statistical correlation between the grapefruit flavor 

components associated with bitter and off flavor i.e. naringin and limonin-- and free and 

suspended pulp levels. See charts in Exhibit 1. 

III. The public benefits to be gained by the proposed revision.

Recent Consumer panel tests run by the University of Florida show no significant 

difference in consumer preference or acceptability between lower sinking pulp values and 

values that exceed grade parameters. See Exhibit 2. Deleting the maximum sinking pulp 

values from the grade standards will allow processors to process the entire grapefruit crop 

(more mature grapefruit tend to be sweeter but when juiced, they can also cause product 

to exceed the maximum free and suspended pulp values) without resorting to expensive 

technologies that drive up the cost of juice for consumers with no concomitant benefit. If 

the parameter is removed from the standard, other grade requirements will remain in 

place that assure quality color, flavor and defects with related consumer preferences. 

3 
Members of the trade that value sinking pulp parameters will be free to continue 

specifying sinking pulp parameters in juice purchase contracts. 

The only other quality consideration worth noting may be the change in “mouth feel” 

(viscosity) due to the potential of higher pulp levels if the parameter is removed. Mouth 

feel is consumer preference influenced. Some consumers could even consider a “lower” 

sinking pulp juice to be “thin” or “watery. Although grapefruit isn’t known for being a 

“thick” product, there are many loyal consumers of fruit juice nectars, which typically 

have much higher viscosity than grapefruit juice. 

Another strong indication that increased sinking pulp volume in grapefruit would be 

accepted by consumers is the fact that USDA eliminated sinking pulp as a grade 

parameter from orange juice standards without any apparent backlash from consumers. 

IV. The revised standards would be practical and objectively enforceable. 

Deleting the sinking pulp requirement will not impact the ability of the USDA to grade 

product on the basis the remaining grade criteria. 

VI. There is broad industry support for the proposed revision.

FCPA contacted known processors of grapefruit juice in North America. Virtually all of 

the major grapefruit juice processors in the United States (Florida, Arizona, Texas and 

California) support the proposed revision and no processor contacted indicated opposition 

to removal of the free and suspended pulp parameter. The parameter at issue is not a part 

of the Codex Standard for fruit juices and nectars (including grapefruit juice), thus repeal 

would not contradict this international standard. 

VII. Conclusion.

For the reasons above, we request that the existing 1983 United States Standards for 

Grapefruit Juice eliminate maximum values for free and suspended pulp. 

FCPA looks forward to cooperating with the USDA and industry going forward on this 

matter. If you have any questions, please do not hesitate to contact us. 

Sincerely, 

Kristen C. Gunter 

Executive Director, FCPA 

cc. Peter Hahn, President, FCPA 

 FCPA Board 

4 
John Bean Technologies Corp. Data Over Six Seasons. 

The following data represents six Florida Grapefruit juice seasons. JBT routinely collects 

fruit throughout each season to process on their pilot lab extraction and finishing 

equipment. Among the data collected, included are results for sinking pulp, naringin, and 

limonin. The graphs illustrate sinking pulp vs. naringin and sinking pulp vs. limonin for 

each of the six seasons. 

The testing protocol was as follows: The fruit tested was obtained from a homogenous 

bin of fruit, all from the same grove lot and picked at the same time. The fruit was 

randomized at the JBT pilot plant, meaning each fruit was hand placed into each sample 

and the samples are prepared simultaneously. This eliminated any possible differences 

from fruit at the top or bottom of the bins etc. Each sample was identical in its sorting 

and selection process to the other. The finisher was set for a constant 160 quick fiber for 

these tests and is monitored on each test. A correction was made if any slight difference 

in the finisher results was detected (in other words, finishing protocol is kept constant 

between all samples). The samples were pasteurized after finishing.

The four most common extractor setups are used on each sample (representing what JBT 

describes as “minimum”, “standard”, and “maximum” setups relative to “hardness” of 

squeeze). 

Data collected from all extractor setups are included on the following graphs since each 

processor could be using any or all of the setups listed above at any given time during the 

season. 

Testing Methodologies: 

Free and suspended (sinking) pulp – per USDA Citrus Handbook 6.16.1 – 6.16.3 

Naringin - Rouseff, R.L. 1988. Liquid chromatographic determination of naringin as a 

detector of grapefruit juice in orange juice J. Assoc. Off. Anal. Chem. 71:798 − 802. 

Limonin - Shaw, P.E. and Wilson, C.W. 1984. A rapid method for determination of 

limonin in citrus juices by high performance liquid chromatography. J. Food Sci. 49:1216 

− 1218. 

Exhibit 1
0

100

200

300

400

500

600

700

0 2 4 6 8 10 12 14

Naringin (ppm)

% Sinking Pulp

04/05

0

5

10

15

20

25

30

0 2 4 6 8 10 12 14

Limonin (ppm)

% Sinking Pulp

Significance F"is NOT >0.05, thus there IS a statistically significant association between X and Y(95%)

Exhibit 1
0

100

200

300

400

500

600

700

0 2 4 6 8 10 12 14

Naringin (ppm)

% Sinking Pulp

05/06

0

5

10

15

20

25

30

0 2 4 6 8 10 12 14

Limonin (ppm)

% Sinking Pulp

05/06

Exhibit 1
0

100

200

300

400

500

600

700

0 2 4 6 8 10 12 14

Naringin (ppm)

% Sinking Pulp

06/07

0

5

10

15

20

25

30

0 2 4 6 8 10 12 1

Limonin (ppm)

% Sinking Pulp

4

06/07

Exhibit 1
0

100

200

300

400

500

600

700

0 2 4 6 8 10 12 14

Naringin (ppm)

% Sinking Pulp

07/08

0

5

10

15

20

25

30

0 2 4 6 8 10 12 1

Limonin (ppm)

% Sinking Pulp

4

07/08

Exhibit 1
0

100

200

300

400

500

600

700

0 2 4 6 8 10 12 14

Naringin (ppm)

% Sinking Pulp

08/09

0

5

10

15

20

25

30

0 2 4 6 8 10 12 1

Limonin (ppm)

% Sinking Pulp

4

08/09

Exhibit 1
0

100

200

300

400

500

600

700

0 2 4 6 8 10 12 14

Naringin (ppm)

% Sinking Pulp

09/10

0

5

10

15

20

25

30

0 2 4 6 8 10 12 1

Limonin (ppm)

% Sinking Pulp

4

09/10

Exhibit 1
The following two graphs contain data from the 09/10 season. The results come from a 

major Florida citrus processor. These samples were taken as pasteurized single strength 

grapefruit juice and represent a myriad of different extractor and finisher setups. 

0

100

200

300

400

500

600

700

0 5 10 15 20

Naringin (ppm)

% Sinking Pulp

09/10

4

5

6

7

8

9

10

11

12

13

0 5 10 15 20

Limonin (ppm)

% Sinking Pulp

LIMONIN

09/10

Exhibit 1
As you can see from the graphs above, from six years worth of data, there is no 

significant association (95%) between naringin vs. sinking pulp and limonin vs. sinking 

pulp except for the Limonin 04/05 graph. That relationship shows that as sinking pulps 

increased, limonin decreased. 

The results from the JBT pilot lab come from juice that was extracted and finished only. 

If centrifuges, homogenizers, and debittering units had been used, it would make a direct 

comparison of sinking pulp to naringin/limonin levels in processed juice even more 

unpredictable. 

This data appears to support the premise that influences of the post 1941 processing 

technologies make sinking pulp quantity an unreliable indicator of juice quality. 

Exhibit 1
The Foundation for The Gator Nation

An Equal Opportunity Institution

Institute of Food and Agricultural Sciences PO Box 110370

Food Science and Human Nutrition Department Gainesville, FL 32611‐0370

352‐392‐1991

352‐392‐9467 Fax

CSims@ufl.edu

Consumer Acceptability of Grapefruit Juice With 2 “Free and Suspended Pulp” Levels 

Dr. Charles Sims, Eric Dreyer, Tom Young 

Participants 

Dr. Charles Sims is a professor in the Food Science and Human Nutrition Department at the 

University of Florida, Gainesville, Florida. Dr. Sims performed the sensory testing in the sensory 

laboratory at the University of Florida. 

Eric Dreyer has a MS in food science and is an assistant to Dr. Sims. Eric was present during the 

processing of the grapefruit juice and brought the juice back to Gainesville. 

Tom Young is with Florida’s Natural Growers, a Division of Citrus World Inc. and coordinated the 

juice processing with John Bean Technologies Corporation (“JBT”) in Lakeland, Florida. 

Purpose of Evaluation: USDA Grade Standards for Grapefruit Juice define “free and Suspended 

Pulp” as “particles of membrane, core, peel and similar particles that settle upon centrifuging a 

sample unit from which the floating fruit cells and floating pulp have been removed.” The USDA 

Grade standards for grapefruit juice prescribe maximum levels for free and suspended pulp ranging 

from 10% to 15%. The purpose of the test was to test consumer acceptability of juice with a free and 

suspended pulp value that exceeded the grade parameter. 

Grapefruit Juice Processing 

Mature and wholesome grapefruit was obtained by JBT personnel and transported to the JBT, 

Lakeland, FL pilot plant on January 13, 2011 and processed into grapefruit juice on January 14, 2011. 

Before processing, the fruit was sized below 3 7/8” and was randomly divided by hand into 4 large 

tubs. The fruit was then extracted, finished, and pasteurized using the JBT pilot plant equipment. 

The extractor was set to a 4 1⁄4” commercial grapefruit setting. The juice was finished in a small JBT 

pilot scale finisher (model 35). A special pan was installed on the finisher to collect 2 different 

concentrations of free and suspended pulp. Approximately 1/3 of the juice came from the discharge 

end where the most pressure is applied to the juice/pulp. Approximately 2/3 of the juice came from 

the intake end where the least amount of pressure is applied. 

The process yielded two juices with different pulp levels: 1) the discharge end juice tested at 18% 

free and suspended pulp (“high pulp”); and 2) the intake end juice tested at 12% free and suspended 

pulp (“low pulp”). The two juice samples were pasteurized at 90C for 10 seconds, cooled to ca. room 

temperature, and filled into 1/2 gallon PET bottles. The two grapefruit juice samples (labeled as “low 

pulp” and “high pulp”) were transported (on ice) from JBT, Lakeland, FL to the Food Science and 

Human Nutrition Department at the University of Florida in Gainesville, FL. There was a total of 2 

gallons of each juice sample. The juice was kept refrigerated at 2C until evaluated on January 18, 

2011. 

Exhibit 2
Sensory Testing 

For the sensory evaluation, panelists were recruited from the University of Florida campus. Potential 

panelists were screened to verify that they were grapefruit juice consumers. They were asked to 

identify which of the following juices they consumed: orange, apple, grape, and grapefruit. If they 

did not say grapefruit, they were not allowed to participate. A total of 86 panelists (41 male, 45 

female, 82% between 18-29 years old) participated in the evaluation. 

Panelists evaluated the juices in individual booths in the Sensory Lab in the Food Science and Human 

Nutrition Department. Approximately 40 mL of each juice were presented to the panelists in plastic 

cups coded with 3-digit random numbers. Juices were kept cold (on ice) and served cold. The juices 

were thoroughly shaken and mixed before pouring into the serving cups, which were immediately 

served to the panelists. The two orders of presentation were presented approximately an equal 

number of times. Panelist were first asked to identify which of the 2 samples they preferred (paired 

preference test), then they were asked to rate the overall acceptability of the samples on the 

traditional 9-point hedonic scale (1=dislike extremely, 5=neither like nor dislike, 9=like extremely). 

They were encouraged to give comments on why they preferred one sample over the other. 

The overall acceptability data were subjected to an analysis of variance to determine if there were any 

significant differences (alpha level of 0.05) between the two juices. For the paired preference test, a 

standard table of critical number of correct responses for a two-sided directional difference test was 

consulted to find the minimum number of correct responses needed for a significant difference at 

alpha 0.05. 

Results 

The data are presented in the attached table. 50 panelists preferred the low pulp juice and 36 

preferred the high pulp juice. The minimum number of correct responses needed for a significant 

difference at alpha 0.05 was 53, so there was not a significant difference in preference. The low pulp 

juice had an overall acceptability rating of 5.87 and the high pulp juice 5.64. The analysis of variance 

indicated that there was not a significant difference in acceptability at alpha 0.05. 

Conclusion 

There was not a significant difference in consumer preference or acceptability between grapefruit 

juices with 18% and 12% free and suspended pulp. 

 

Investigator and Cooperator Contact Information: 

Dr. Charles Sims: 359 Food Science and Human Nutrition Building/P.O. BOX 110370/Newell Drive, 

University of Florida, Gainesville, FL 32611-0370/Email: 

casims@mail.ifas.ufl.edu

Tom Young: Florida's Natural Growers/A Division of Citrus World, Inc./20205 US Highway 27 

North, Lake Wales, Florida 33853/ tom.young@citrusworld.com

Donn Sabato: John Bean Technologies Corp. 400 Fairway Ave. Lakeland FL 33803/Tel. 863-683-

5411/ Donn.sabato@jbtc.com

Exhibit 2
Grapefruit Juice Sensory Results, January 18, 2011 

Acceptability 

Treatment # Preferring Rating

Low Pulp 50 5.87 

High Pulp 36 5.64 

NS NS 

86 panelists (41 male, 45 female, 82% between 18-29 years old, 

screened to say they drink grapefruit juice) 

Minimum number of panelists preferring to be significant = 53, 

alpha level of 0.05, 2-sided test 

Acceptability ratings range from 1-9, with 1=dislike extremely, 

5=neither like nor dislike, 9=like extremely, no significant 

differences 

according to analysis of variance, alpha=0.05 

Exhibit 2