FLORIDA
154
STATE
HORTICULTURAL
The presence of such substances might
be particularly significant in the case
slightly below
a
level
inability
of
could explain
selective
media
to
and
and V.
S. Troy.
1949.
The
test
in
the
examination
American
Food
of
frozen
Fruit Products Jour,
Manufacturer.
28
(11):
356-357.
2.
Standard
1946.
Methods
Standard
of
Water
Methods
of Water and Sewage.
the
detect
G.
concentrated orange juice.
incubation temperature above the opti
coliforms,
C.
presumptive
which coliforms themselves are affected.
mum for
Beisel,
Vaughn-Levine boric acid medium as a screening
at
These factors, in combination with an
1950
LITERATURE CITED
1.
of media containing inhibitors in con
centrations
SOCIETY,
for
the
Analysis.
Examination
Ninth Edition.
American
Public Health Association, New York.
3.
Wolford, E. R.
1950.
Bacteriological studies
on frozen orange juice stored at — 10°F.
these organisms in some instances.
Technology.
4
(6):
Food
241-245.
STORAGE CHANGES IN CITRUS MOLASSES
of
R. Hendrickson1 and
J. W. Kesterson2
amine Table 1 wherein the comparative
Citrus molasses, which has become a
familiar livestock feed in Florida has
ten
commercially
years.
Its
wide
for
less
acceptance
and. increasing popularity warrant more
complete understanding of its physical
and chemical properties.
Buyers of this
carbohydrate concentrate are interested
in
obtaining
further
information
re
garding the product, storage changes,
and
the
ramifications
of
microorgan
isms associated with it.
Citrus molasses is produced from the
rinds and pulp of citrus after the juice
has been expressed.
This waste resi
due is chopped, limed, and pressed to
yield
a
(percent
press
liquor of
soluble
weight)
which
72°-75°
Brix
solids
when
is
the
take
citrus molasses it might be well to ex
Introduction
than
changes
Before discussing storage changes in
Lake Alfred
produced
Certain
subject of this report to industry.
Citrus Experiment Station
been
cattlemen.
place during storage and they are the
10°-14°
common molasses obtained from sugar
refining
concentrated
is
presented.
analysis for
clarified
The
average
citrus
molasses
represents samples made from several
varieties of both grapefruit and orange.
Clarified molasses refers to a product
made from a clear press liquor.
It is
immediately noticeable that blackstrap
is generally concentrated to a higher
degree Brix, but has the disadvantage
of having more than a proportionately
higher
ash content.
Citrus molasses
producers tend now to use 72° Brix as a
minimum value with the average being
maintained at a higher level.
Sugar Losses and Instability
Brix
content
.final
analysis between this product and the
During Storage
by
to
In storage, citrus molasses has been
molasses.
found to slowly undergo both a physical
Since citrus molasses can be produced
and chemical transformation.
only during the processing season, the
mount importance are the changes in.
Of para
processor is required to store millions
sugar content which occur on storage.
of gallons to serve the year round needs
When ten samples of citrus molasses
collected from ten commercial proces
1 Assistant Chemist, Citrus Experiment Station, Lake
Alfred, Florida.
a Associate Chemist, Citrus Experiment Station, Lake
Alfred, Florida.
sors
lyzed
in January of 1948 were reana
by
the
Lane-Eynon
Volumetric
procedure they were found to have lost
11ENDR1CKSON
AND
KESTERSON: CITRUS MOLASSES
155
TABLE 1.
COMPARATIVE DATA ON CITRUS AND BLACKSTRAP MOLASSES.
Analysis
Commercial1
Clarified3
Louisiana*
Cuban8
Citrus Molasses
Citrus Molasses
Blackstrap
Blackstrap
Brix°
72.0
73.1
90.7
87.2
Sucrose %
19.6
26.1
30.1
37.3
Keducing Sugars
%
22.9
24.9
26.4
16.6
43.5
52.4
58.0
55.8
Carbonate Ash %
4.7
3.0
10.8
10.9
Nitrogen % X 6.25
4.1
3.6
1.6
2.1
PH
5.0
5.9
5.7
5.5
Total Sugars %
1 Average of 36 samples.
2 Average of 16 samples
• Fort (3).
(laboratory prepared).
(See literature cited).
an average of 1.7 percent total sugars
able
per year of storage.
and since only the supernatant liquid
Similarly, 13 sam
insoluble
matter
during
storage
ples collected in April of 1948 from 11
was analyzed it is understandable that
producers were found to have lost an
the percent total sugars could increase
average of 3.2 percent total sugars per
even in the face of a slow deterioration
year of storage.
are
13
In contrast, however,
samples
of
clarified
citrus
of sugars during storage.
Table 2 sum
marizes these data showing maximum
molasses made in the laboratory from
and minimum values as well as a com
different varieties
parison of sugar losses noticed in black
of
both
grapefruit
and orange that showed an average in
strap during storage.
crease of 0.4 percent total sugars per
gating
the
year of storage.
found
that
These clarified citrus
molasses samples precipitated consider
highest
Owen (6) investi
deterioration
those
total
of
samples
sugar
blackstrap
having
values
the
were most
TABLE 2.
COMPARISON
CITRUS
OF
MOLASSES
Description of Sample
Commercial Citrus Molasses
January 1948
Commercial Citrus Molasses
April 1948
Clarified Citrus
SUGAR
Molasses
AS
No.
LOSSES
DURING
COMPARED
of
Type
WITH
of
STORAGE
OF
BLACKSTRAP.
Change in Total Sugars per
Samples
Value
10
Maximum
-3.4
Minimum
-0.6
Average
13
13
Year of
Storage
(Calculated
-1.7
Average
-3.2
Maximum
-7.7
Minimum
-1.3
Average
+0.41
Maximum
-1.3
Minimum
+ 1.41
Blackstrap2, Factory No. 1
1
-6.3
Blackstrap2, Factory No. 2
1
-11.9
Blackstrap,2 Factory No. 3
1
-11.3
1 Actually increased in percent total sugars (See text)
»Owen (6)
%)
FLORIDA
156
HORTICULTURAL SOCIETY,
1950
in
produced darkening and gas which was
Upon examining each of the 3
further accelerated by certain metallic
susceptible
storage.
STATE
to
actual
deterioration
groups of citrus molasses samples pre
ions. Hucker and Brooks (5) also demon
viously
strated that gas is produced by mixtures
mentioned,
it
was
noted
that
within each group this same correlation
of nitrogen compounds and glucose, a re
generally held true for citrus molasses.
action which is more commonly known
The clarified samples of citrus molasses,
as the Maillard reaction.
however,
deteriorate with the
chemicals were added in small quantities
for their high
did
not
When various
total
to citrus molasses under manometric ob
sugar content and is probably accounted
servation it was noticed that formalde
for by the removal during clarification
hyde,
of some colloidal unstable organic sub
gated
stances contributing to this deterioration.
changes on the acid side had little effect.
rapidity
expected
though impractical to
gas
formation,
use,
and
miti
that
pH
Although there has been a loss of total
While studying this spontaneous foam
sugars in each of the commercial citrus
ing it was noticed that certain commer
molasses
cial citrus molasses samples had shown
samples
corresponding
during
change
in
storage,
degree
the
Brix
sub-surface
gas
but a fraction of the percent of total
samples were disturbed they tended to
foam more readily much like a carbon
beverage.
storage.
When
the
sugars lost.
ated
of
during
first
The froth fermentation or spontaneous
months
formation
is so small as to be insignificant, being
Analysis
of
a
these
citrus
foaming of molasses has been the subject
molasses
of much inquiry, for even though it hap
excessively showed no significant differ
pens
infrequently,
it can
be
a
serious
economic loss.
This phenomena occurs
when
spontaneously
molasses
heats
to
sample from a tank foaming
ence from other samples on hand.
This
particular storage tank was finally con
trolled
by
aeration
which
may
have
such high temperature as to "boil" and
helped only by its agitation action on the
foam out of its storage tank leaving but
surface foam, and it follows also that the
a charred mass.
Usually the molasses
reaction may already have spent itself.
foams to some multiple volume that is
It
greater than the storage space available.
samples
All attempts to correlate this instability
made in the laboratory only two have
with
shown any sign of sub-surface gas for
some
other
chemical
or
physical
analysis have been futile to date.
Owen
(6) corroborates this and further states
regarding
blackstrap
terioration
"that
involving loss
actual
of
de
sugars is
appears
significant
of
clarified
that
of
citrus
twenty
molasses
mation and both of these samples had an
excessive precipitation of insolubles dur
ing
storage.
None
of
these
samples
showed any sign of surface foaming and
accompanied by gas evolution, but it is
they have the further advantage of hav
also true that the latter cannot be taken
ing a less stable foam system.
as
of
the
of
foams, are high viscosity and finely di
an indication of the destruction
sugars."
gas
Manometric
evolution
molasses
from
samples
was
measurement
conditions
contributing
Among
to
stable
various
citrus
vided solids, both of which have been re
similarly
found
duced
by
clarification.
Hucker
and
not to correlate with loss of sugars. This
Brooks (5) have demonstrated that high
gas formation in citrus molasses can also
viscosities tend to increase the chances
be found in concentrated orange juices
of spontaneous foaming and that high
and was investigated by Curl
storage temperatures further aggravate
studied
synthetic
mixtures
(2) who
and
found
that mixtures of amino acids and sugars
this condition with
40°-45°C.
critical temperature range.
being a
HENDRICKSON
AND
157
KESTERSON: CITRUS MOLASSES
theory whereupon it is believed that the
Many explanations of froth fermenta
source of gas formation is the reaction
tion have been advanced over the years,
but most agreement has been found in
between amino acids and invert sugar.
two theories; one, the glucic acid theory
Hucker and Brooks (5) seemed to have
which is favored by Browne (1) and re
definitely
established
lates that the action of lime on invert
isms
be
sugar
cause.
produces
unstable
organic
sub
stances that further reacts with invert
sugar.
The
second
is
the
can
that
considered
microorgan
only
a
minor
Influence of pH During Storage
Although the initial pH of a citrus
Maillard
-WO
-1.20
0
O>
O
Jtak
0
loo
c
*w
3
Q
-.80
X
a
c
■-.60
a>
a*
c
a
-.40
014 Months Storage
• 20Months
o
Time
Storage Time
~.2Q
6
6,5
Original
Figure
1.
molasses
A
scatter
after
1U
diagram
months
molasses after 20 months.
5.5
Molasses
pH
comparing the change in pH of clarified citrus
storage
versus
the
change for
commercial citrus
FLORIDA
158
STATE
HORTICULTURAL SOCIETY,
press liquor is almost entirely controlled
1950
was noticeable that almost without ex
by the quantity of hydrated lime added
ception the percent of total sugars as
to the chopped citrus peel, there are cer
invert sugar had increased with there
tain other factors to be considered in
being a tendency for the samples having
arriving
at
the
final
molasses
sample
in
pH
of
a
storage.
citrus
Attempt
the lower pH to show the greater percent
change.
should be made to control the initial pH
In studying the clarification of citrus
of citrus molasses between the limits of
molasses it was found that in storage
6.0 to 6.5 with due thought given to the
clarified molasses precipitated consider
destructiveness and other inherent dis
able insoluble matter and that variations
advantages
in pH between 4 and 8 did not perceptibly
sugars.
of
excessive
alkalinity
on
Consideration must be given by
processors to the corrosive and destruc
decrease the quantity precipitating.
It
is also to be noted that pH could not in
tive influence of a too acid molasses on
any way be correlated with sugar losses,
storage equipment.
or
ized
that
It is generally real
grapefruit
peel
demands
greater quantity of lime than
however,
during
processing
prolonged heating it is
a
orange,
and
upon
to be further
spontaneous
It
has
undoubtedly
noted that both citrus press liquor and
molasses will decrease in pH.
storage tends
crease in pH averaged one unit for 14
samples that were processed to citrus
molasses
in
the
laboratory.
During
storage there is a further drop in pH of
citrus molasses samples.
The decrease
in pH appears to be dependent upon both
of
citrus
Physical Changes During Storage
recognized
This de
frothing
molasses.
that
citrus
to
been
previously
molasses
increase
in
upon
viscosity,
sometimes appearing to gel, but hitherto
an explanation has been lacking.
This
increase is strikingly seen in Figure 2
in which is plotted the viscosities of 18
samples of commercial citrus molasses
after over one year of storage against
the time of storage and the pH of the
their Brix, versus 11 samples of commer
sample at the time it was put in storage.
cial
Figure 1 is a scatter diagram of 11 sam
storage only one month.
ples of clarified citrus molasses stored
for 14 months and 17 samples of commer
cial citrus molasses that have been stored
for 20 months, wherein the change in
pH during storage is plotted against its
pH at the time it was put in storage. Be
low a pH of 4.5 the decrease in pH with
time is of smaller magnitude than would
be anticipated from this figure and would
appear to be approaching a point of little
change.
Prior to storage the quantity of total
sugars
found
as
reducing
sugars
in
citrus molasses is definitely related to the
pH of the processed molasses.
As was
lines
citrus
show
molasses
a
that had
been
in
The regression
considerable
increase
in
viscosity with time. Four other molasses
samples whose Brix were between 68°
and 73° had solidified and are not shown
in this diagram.
The wide variation of
viscosities for samples of similar Brix
is largely due to the quantity of sus
pended
insolubles
viscosities
of
present.
many
When
clarified
the
molasses
samples were plotted in similar fashion
against
those
of
nonclarified
citrus
molasses by Hendrickson (4), the regres
sion line for clarified molasses showed its
viscosity to be seven times smaller and
showed less viscosity variation between
similarly found in the analysis of Va
samples.
lencia orange juice by Roy (7), the lower
and Brix upon the viscosity of an excel
The influence of temperature
the pH the greater the ratio of reducing
lent sample of commercial citrus molasses
to nonreducing sugars.
prior to storage can be seen in Figure 3.
In
storage it
HENDRICKSON AND
KESTERSON: CITRUS MOLASSES
O After over I
Year
• After approx, I
7i
72
Degree
73
74
159
Month
75
78
Brix
Figure 2. A scatter diagram, comparing the viscosity at 30°C. of citrus molasses
samples stored for over one year versus samples that had been in storage ap
proximately one month,
FLORIDA
160
STATE
HORTICULTURAL
SOCIETY,
1950
%^-te
60
72
68
64
800
000
vs..
O
400
vs'
.At 75.0* -Brw
At
Viscosity
:
:'. ;"
30.0° CenHgrade
200
o
O
80
60h
*o
40
c
o
20
>*
^™»
o
u
€0
10
>
8
20
,
:
Figure 3.
molasses.
30
Tdmperafurt
40
^C V
50
60
70
..-.••/. I\\
Influence of concentration and temperature upon the viscosity of citrus
HENDRICKSON AND KESTERSON: CITRUS MOLASSES
Since the insoluble matter is mostly
Conclusions
responsible for the wide variations in
viscosity, it is well to examine the source
161
In
retrospect,
citrus
molasses
was
concentrating
found to lose an average of 2-3 percent
total sugars per year of storage while
citrus press liquor to citrus molasses it
clarified citrus molasses showed little if
has been noted as having anywhere from
any loss.
0.2-0.5 percent by weight insoluble mat
degree Brix of these samples, being but
of
insolubles.
ter
Prior
depending
to
upon
how
it
has
screened and the degree of liming.
been
a
Dur
molasses
There was little change in
fraction
of
the
samples
sugar
loss.
having
the
Those
highest
ing the process of evaporation another
total sugars appeared most susceptible to
one to three percent, on a citrus molasses
loss of sugars in storage although other
basis, of calcium organic salts are esti
unknown
mated to precipitate.
equally
siderable
quantity
In storage a con
of
insoluble
matter
has been noted to precipitate which is
especially noticeable
molasses samples.
in
clarified
citrus
A greater quantity
of insolubles was found to precipitate
factors
would
important.
The
appear
to
be
spontaneous
foaming of citrus molasses was investi
gated, but could not be correlated with
any chemical or physical analyses. Clari
fied citrus molasses, however, showed a
perceptible improvement in stability.
from clarified grapefruit molasses than
The pH of citrus molasses was noted
from the clarified orange samples, with
to decrease with time and was greatest
one sample of grapefruit molasses pre
for those samples having the higher pH.
cipitating
5.6
percent
insolubles
by
Below a pH of 4.5 the samples appeared
weight, two-thirds of which was soluble
to approach a point of little change. The
in alcohol.
ratio of reducing to nonreducing sugars
It is not strange then for the
amount of insolubles to build up to a
rather high percentage.
For example,
one commercial molasses sample that had
solidified was observed to have 9.6 per
cent insolubles.
Examining more closely the volumin
ous quantity of insolubles precipitating
from grapefruit molasses samples it was
noted
that
the
majority
of
insolubles
were crystalline and appeared as clusters
of needles growing from common cen
ters.
In Figure 4
is
shown
a photo
micrograph of these crystals which were
subsequently identified as naringin. The
Figure U-
very bulkiness of these crystalline needle
gin in citrus molasses. (Magnified 50 X)
A microphotograph of narin
formations, as well as the quantity of it,
the
was found dependent in part upon pH
and there was a tendency for samples
cause of increasing viscosities in storage.
having the lower pH to show the greater
By
increase in percent inversion.
and the percent of calcium organic salts
precipitating
heating
in
storage
the
citrus
points
to
molasses
the
naringin crystals will, by virtue of their
During storage, there was an increase
increased solubility, go back into solution
in viscosity which was felt to be caused
and remain as a supersaturated solution
by
for some time.
tating.
Upon closer examination some
of
insolubles
Hesperidin has not been
isolated from orange molasses to date.
the
the
quantity
of
insolubles precipi
were
found
to
be
162
FLORIDA
naringin
which
STATE
crystallized
in
HORTICULTURAL
SOCIETY,
needle
A.
2.
have
Upon
considerable
heating,
the
calcium
naringin
content.
is
redis-
solved and remains in solution for a con
siderable length of time.
The viscosity
ease in handling the product.
LITERATURE CITED
1.
Browne, C. A.
The spontaneous decomposition
Ind. Eng. Chem. 21:
Gas
and
formation
Fort,
C.
A.
Variable
blackstrap molasses.
4.
1948.
of
Sugar, November, 1946.
Hendrickson, R.
Florida citrus molasses.
Fla.
1950.
Hucker, G. J. and R. F. Brooks.
Gas produc
tion
Research
in
storage
481-92.
6.
concentrated
mineral composition
Agr. Exp. Sta. Bui. 469: 5-14.
5.
in
analagous synthetic mixtures.
Food Research 13: 381-6.
3.
of the molasses sample meanwhile will
have been greatly reduced, allowing more
L.
orange juices
fashion while another portion was found
to
Curl,
1950
molasses.
Food
7:
1942.
Owen,
W.
syrups
and
L.
The
molasses
microbiology
275
pp.
of
1949.
sugars,
Burgess
Publishing Co.
7.
Roy, W. R.
Effect of potassium deficiency and
of potassium derived from different sources on
the composition of the juice of Valencia oranges.
/. Agr. Res. 70: 143-169.
1945.
of sugarcane molasses.
600-06.
1929.
AN INDEX OF PASTEURIZATION OF CITRUS JUICES
RY A RAPID METHOD OF TESTING FOR RESIDUAL
ENZYME ACTIVITY1
Theo. J. Kew and M. K. Veldhuis
also destroys cloud stability in the canned
U. S. Citrus Products Station2
product and if it is not inactivated dur
Winter Haven
In the course of some investigations on
the effect of different temperatures and
rates of heating used in the pasteuriza
tion of citrus juices, it became evident
that there was need for a simple test for
determining the presence of the pectinesterase enzyme. An investigation was
started and a test was developed that is
more rapid than those now available. It
has been found useful in the experimental
work and should be of value in deter
mining the adequacy of pasteurization in
commercial packs.
The test is simple,
rapid, gives positive results, and is suit
able for routine use in control labora
tories of canning plants.
The test is based on the activity of the
pectinesterase enzyme which hydrolyzes
ing pasteurization, the juice in the upper
portion of the can will be clarified and a
sludge will settle to the bottom or a curd
may
form.
tested,
the
Of
the
enzyme
pectinesterase
systems
re
quires the highest temperature for inactivation.
Canned juice should be as
stable as possible and to this end it is con
sidered desirable that all enzyme systems
be inactivated.
enzyme
Excessive heating is also
to be avoided to decrease the danger of
scorching and the development of unde
sirable flavor changes.
In general, the
organisms which will grow actively in
citrus juices are destroyed at tempera
tures below those required for enzyme
inactivation.
One of the procedures investigated was
that
suggested
by
Jansen
(1).
This
method was to centrifuge the cloud from
methyl ester groups to give acid groups
the juice as much as possible;
which increase the acidity.
this cloud material with quarter molar
This enzyme
extract
sodium chloride, maintaining the pH at
1 Report of a study made under the Research and
Marketing Act of 1946.
2 One of the laboratories of the Bureau of Agricul
tural and Industrial Chemistry, Agricultural Research
Administration, U. S. Department of Agriculture.
7.5
and
after
filtration,
assaying
this
solution for pectinesterase by the pro
cedure
described
by
Lineweaver
and
Ballou (2) and MacDonnell, Jansen and