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that company. Several other lots of seedlings from crosses made at East Ware-
ham are set out in permanent locations on the State Bog where they will be al-
lowed to grow until final assessment of their worth for propagation can be made.

Oxygen Content of Winter Flooding Water in Relation to Injury to Cranberry
Vines. (H. F. Bergman.) Studies of the effects on cranberry vines of a lack of
oxygen in the water during the winter flooding period were continued, in an
attempt to correlate various types of injury with known low contents of dis-
solved oxygen over approximately known periods and to obtain additional data
as to the conditions under which injury occurs. Three cylindrical sheet-iron tanks,
about 5 feet in diameter, were placed on the State Bog, one each on sections
panted with vines of Early Black, Howes, and McFarlin varieties. The bog
was flooded on December 5, 1940, and froze over within a few days and remained
frozen continuously until about the middle of March. Covers to exclude light
and thereby prevent the liberation of oxygen by photosynthesis were placed on
the tanks on January 18, 1941.

The importance of photosynthesis in maintaining the dissolved-oxygen con-
tent of the water on a winter-flooded bog covered with ice is shown by the course
of this oxygen content outside and inside the tanks during the winter. The
amount of dissolved oxygen in the water outside the tanks on Howes, Early
Black, and McFarlin vines increased from 5.3, 6.4, and 6.8 cc. per liter, respec-
tively, on January 15 to 7.2, 7.9, and 8.3 cc. per liter, respectively, on January
24 as a result of photosynthesis in the cranberry vines. A heavy snowfall on
January 24 prevented photosynthesis by excluding light, while the consumption
of oxygen by respiration of the cranberry vines and of organisms which decom-
pose organic matter continued. As a result the dissolved oxygen in the water
outside the tanks decreased to less than 2 cc. per liter, although probably for not
more than 5 or 6 days. A heavy rain on February 7 removed most of the snow
and the remainder froze into the ice. Thereafter, the dissolved oxygen in the
water outside the tanks on Early Black and McFarlin vines increased rapidly,
and by February 12 it had come up nearly to the same content as on January 24.
The oxygen content of the water outside the tank on Howes vines remained near
2 cc. per liter until February 20 when it also began to increase.

The dissolved oxygen in the water inside the tanks on January 15 varied from
4 to 5 cc. per liter. Because of the exclusion of light by the covers, little or no
photosynthesis could take place and the oxygen content of the water decreased
steadily. By January 24 and from then until February 27 there was no dis-
solved oxygen in the water inside the tank enclosing vines of the Howes variety,
and not more than 0.4 cc. per liter from February 27 until March 20. In tanks
enclosing the other two varieties of vines there was less than 1 cc. of oxygen per
liter of water for about a month from February 1 to March 1 except in the tank
on Early Black vines where the oxygen content of the water increased to slightly
more than 2 cc. per liter for a few days around February 12. On February 28
nine inches more water was pumped onto the bog which brought the oxygen
content of the water up to more than 2 cc. per liter. Thereafter, e.xcept for a few
days about March 13, there was never less than this amount of oxygen in the
water. Soon after March 20 the ice went off the bog and the dissolved-oxygen
content again increased.

The water was taken off the bog on April 1, 1941, and the tanks were then
removed. Counts were made during the summer and autumn to ascertain the
average number of flowers and fruits per upright, the percentage of buas killed,
and the percentage of flowers that set fruit on vines of each of the three varieties
both inside and outside the tanks where the dissolved oxygen content of the water



42 MASS. EXPERIMENT STATION BULLETIN 388

during the winter flooding period was known. The yield of berries of each variety
inside the tanks and on measured areas outside was determined.

The effect of an insufficient supply or of complete deprivation of oxygen over
a period of a month or more during the winter flooding period is shown clearly
by the reduction in yield of berries from vines inside the tanks in comparison with
vines outside. Furthermore, the yield outside but near the tanks was very much
less than that from vines on slightly higher ground and therefore less deeply
flooded. The yields, in barrels per acre, were as follows: Early Black, inside
tank 28, outside near tank 34, on slightly higher ground 75; Howes, in the cor-
responding locations, 50, 72, and 110; and McFarlin, inside tank 39, outside on
higher ground 81.

Although the dissolved-oxygen content of the water on the less deeply flooded
areas during the winter was not determined, it has been found repeatedly that
the oxygen content of water is less in deep places than in shallow, even a few
inches making a significant difference,- particularly when there is ice over the bog.
It is probable, therefore, that the oxygen content of the water in the less deeply
flooded "high" places did not fall below 2 cc. per liter for more than one or two
days during the winter, if at all. This indicates that if the dissolved-oxygen
content of the water is less than 2 cc. per liter for even a few days the j'ield is
greatly reduced. A longer period of oxygen deprivation caused a further reduc-
tion in yield, but even within a variety the reduction was not proportional to the
length of time during nvhich the oxygen deficiency existed. Prolonged oxygen
deficienci' affected vines of different varieties differently. There was no oxygen
in the water inside the tank on Howes vines for nearly two months; yet these
vines yielded better than Early Black vines inside a tank in which the ox^'gen
in the water was less than 1 cc. per liter for not more than a month and approached
exhaustion for about two weeks only. This probably is because the Early Black
vines had been badly injured by a lack of oxygen in the water during the flooding
period of the Winter of 1939-40 and therefore were more susceptible to injury.

The first effect of an oxygen deficiency during the winter flooding period is to
reduce the number of flowers that set fruit. Injury of this kind apparently may
occur if there is less than 2 cc. of dissolved oxygen per liter in the water for as
short a time as 3 or 4 days. In all three varieties the percentage cf flowers setting
fruit was lowest on vines inside the tanks, where the oxygen deficiency was great-
est, and was lower on vines in slightly deeper water than on those most shallowly
flooded, although in some cases the difference was small.

A greater deficiency of oxygen or a deficiency over a longer time causes the
death of flower buds and then of the uprights on which the flowers are borne.
The percentage of dead buds on vines of all three varieties in the areas outside
but near the tanks was considerably greater than it was on vines on slightly
higher ground. In the Early Black and Howes varieties the percentage of dead
buds on vines inside the tanks was slightly less than on those outside, whereas
it should have been greater. One reason for this discrepancy may be that more
of the flower buds on vines inside the tanks than on those outside were killed at
such an early stage of development that they were not detected when the counts
were made. This is indicated by the lower average number of flowers per upright
for these varieties on vines inside than on those outside the tanks. Another
reason is that in making the counts only flowering uprights were taken; no atten-
tion was paid to sterile ones, a considerable proportion of which probably were
flowering uprights on which the buds had been killed at a very early stage of
development. For the same reasons the values for the percentage of flowers
setting fruit on vines of the Early Black and Howes varieties inside the tanks
are higher than they would otherwise have been.

The average size of berries from vines inside the tanks was smaller than that of



ANNUAL REPORT, 1941 43

berries from vines just outside the tanlcs or from vines on slightly higher ground.
Berries of the Early Black variety showed the greatest difference. Those from
vines inside the tank averaged 158 to the cup (J^ pt.); from vines just outside,
118 (average of 93 counts); and from vines on slightly higher ground, 110 (20
counts). The average number of berries per cup for the other two varieties was as
follows: Howes, inside tank 115, outside near tank 105, outside on slightly higher
ground 100; McFarlins, inside tank 94, outside near tank 94, on slightly higher
ground 84. Many berries failed to grow to a size large enough to be picked. The
proportion of these berries was greater from vines inside the tanks or from vines
outside near the tanks than from vines on higher ground.

The reduction in the size of picked fruits and the failure of berries to grow
to a size large enough to be picked probably is due to an inadequate food supply
during the summer because of injury to the leaves of the preceding season which
reduced their capacity to synthesize carbohydrates. Vines of all three varieties
inside the tanks lost more of their old leaves than did vines outside. This was
true especially of Early Black which lost nearly all the old leaves from vines
inside the tank. Even when old leaves remained on the vines, many of them were
injured and probably their effectiveness in the formation of carbohydrates was
greatly reduced.

The following conclusions are drawn: Injury to cranberry vines occurs when
the dissolved-oxygen content of the water falls below 2 cc. per liter. This happens
apparently only when the ice on a winter-flooded bog is covered with snow,
which excludes light and thereby prevents photosynthesis and the resultant
liberation of oxygen which ordinarily keeps the oxygen content of the water
high enough to prevent injury. The injurious effect on cranberry vines of a lack
of oxygen for several days to a few weeks is shown ultimately in the reduction
of the crop. Reduced yields are the direct result of (1) reduction in the number of
flowers setting fruit, (2) death of flower buds and flowering uprights, and (3) re-
duction in the size of fruits, both those harvested and those too small to pick.



DEPARTMENT OF DAIRY INDUSTRY

J. H. Frandsen in Charge

Studies on Chocolate-Flavored Milk. (W. S. Mueller.) The study of choc-
olate-flavored milk, with especial emphasis on its nutritive value, continues to
be a major project in this department. For a long time it had been assumed
that the well-known nutritive properties of plain milk were also present in choc-
olate-flavored milk. In 1937 it was discovered that milk containing 2.5 percent
or more of cocoa was not equal in nutritive value to plain milk, when fed to white
rats. Since then experiments have been in progress to learn more about the
various constituents of cocoa and their possible effects upon the nutritive value
of the milk. In addition to the nutritional studies, investigations on improving
the method for processing chocolate milk are in progress.

1. The Effect of Cocoa Upon Digestibility of Milk Proteins. (L. D. Lipman
and W. S. Mueller.) The addition of cocoa to whole milk powder in quantity
equivalent to approximately 3.6 percent by weight on a fluid milk basis reduced
the digestibility of the milk protein 7.8 percent. The kind of cocoa, Dutch or
American-process, and the inclusion of 7.1 percent of cocoa fat in the ration,
did not significantly affect the percentage reduction. Proteins of the Dutch and
American-process cocoa were found to be 38.1 and 44.5 percent digestible, re-
spectively. The results of this study were published in the Journal of Dairy
Science 24, May 1941.



44 MASS. EXPERIMENT STATION BULLETIN 388

2. The Significance of Tannic Substances and Theobromine in Chocolate Milk.
(W. S. Mueller.) The relative toxicity of pure theobromine, pure tannic acid,
and two cocoa powders varying in content of tannic .substances was determined by
feeding these substances in a basal diet to white rats. Theobromine was non-
toxic to albino rats when the ration contained 0.27 percent of this alkaloid, and
tannic acid was toxic when the ration contained 2 percent of this substance.
These amounts of tannic acid and theobromine in the diets were equal to those
in a chocolate milk made with 3.6 percent cocoa powder which contained 12.15
percent tannic substances and 1.7 percent theobromine. A cocoa powder con-
taining 12.15 percent of tannic substances was more toxic than a cocoa powder
containing only 2.67 percent of tannic substances, but was less toxic than pure
crystalline tannic acid. A concentrated extract of cocoa was non-toxic to rats
when fed at the rate of 8 percent of the ration. The hemoglobin levels of the
blood of rats fed theobromine, crystaline tannic acid, and cocoa powder contain-
ing varying amounts of tannic substances did not vary from the normal enough
to be of any significance. Results from this study indicate that the toxicity from,
cocoa can be greatly reduced by selecting a cocoa or chocolate which is low in
tannic substances, or preferably by using an extract of cocoa as the flavoring ma-
terial when feasible.

3. The Availability of the Iron of Cocoa and of Additional Iron when Asso-
ciated with Cocoa. (F. Kinder, H. S. Mitchell, and W. S. Mueller.) This study is
reported by the Department of Home Economics Nutrition.

4. Effect of Adding Cocoa to Cow's Milk on the Utilization of Calcium and
Phosphorus. (M. R. Cooney and VV. S. Mueller.) This study is reported by the.
Department of Home Economics Nutrition.

5. The Bacteriology of Chocolate Milk, Chocolate Syrup, and Cocoa Powders
(R. W. Swanson, J. E. Fuller, and W. S. MueUer.) This study is reported by the
Department of Bacteriology.

6. Effect of Cocoa on the Vitamin C Content of Milk. (W. S. Mueller.) Vita-
min C is present in fresh raw milk to the extent of 12 to 20 mg. per quart. If
this could all be retained, milk would be a significant source of vitamin C, since
the higher figure is about half the daily requirements of an adult. Therefore, the
handling of milk from the time it is drawn until it is consumed, in a manner
which will conserve the vitamin C, is an important problem today.

If chocolate milk is substituted for plain milk, it is important to know what
effect the cocoa has upon the retention of vitamin C. Preliminary studies on the
relative retention of vitamin C in plain milk and chocolate milk have been made,
using the 2, 6-dichloro-phenol-indophenol in both visual and electrometric titra-
tions. Results of these studies indicate that the addition of cocoa to milk hastens
the destruction of vitamin C. When both milks were stored, under identical
conditions, the plain milk lost 22 percent of the original vitamin C, while the
loss for chocolate milk was 77 percent. This difference in loss of vitamin C is
typical of the results obtained. Studies are also being made to determine which
method is most suitable for measuring the vitamin C content of chocolate milk.

7. Effect of Cocoa on the Coagulation of Milk. (W. S. Mueller.) It has been
reported by a foreign investigator that cacao bean contains an enzyme with
rennet effect. Dry, it withstands heating to 248°-284° F. and may, therefore,
be found in cocoa powder. The optimum temperature of the enzyme is 149° F.
and the optimum pH is below 6.3. By heating a suspension of cocoa powder in
water (176° F.), the enzyme will be destroyed.

Since the knowledge of this enzyme may be of practical interest to the con-
sumer as well as to the manufacturer of cocoa, a study was undertaken to deter-



ANNUAL REPORT, 1941 45

mine whether cocoa powders commonly sold in this country contain such an
enzyme. In preliminary studies 25 samples of cocoa powder have been investi-
gated. When one percent of cocoa powder, by weight, was added to good quality
milk (.16 percent acidity), only one cocoa powder coagulated the milk shortly
after heating at 149° F. for 30 minutes. Further investigation will be made,
using milk of higher acidity and of a low protein stability, and also adding a larger
amount of cocoa to the milk.

8. The Effect of Various Methods of Pasteurization on Chocolate Milk. (W. S.
Mueller and A. M. Shipley.) Further experiments in pasteurizing chocolate-
flavored milk by the Electropure process substantiate in a general way the results
of last year. However, in the latest trials, the Electropure method was more
efficient in the reduction of the bacteria count of highly viscous chocolate milks.

Cooperative Study with the American Dairy Science Association Committee
on Methods for Determining the Curd Tension of Milk. (W. S. Mueller.) The
final report of the committee on methods of determining the curd tension of milk
was published in the Journal of Dairy Science, 24, September 1941.

Improving the Flavor and Keeping Properties of Milk and Some of its Products.

(VV. S. Mueller and M. J. Mack.) A major flavor defect of orange or lemon ice
and sherbet is the development of terpene odors and flavors, as a result of the
oxidation of the oil in the flavoring material. It seems logical that this flavor
defect could be prevented or minimized by the addition of an antioxidant.
Therefore, the antioxygenic effect of oat flour and of a concentrated extract of
oat flour was studied by adding 0.5 and 0.1 percent of these substances, respec-
tively, to lemon and orange ices. Fresh orange and lemon juice were used as the
flavoring materials. The control samples developed a harsh flavor after four
days, while the samples containing the antioxidants had a typical orange and
lemon flavor for several weeks. In the concentrations used, the concentrated
extract of oat flour was slightl)- more effective than the powdered oat flour. A
protective action was also noted when a sugar which had been treated with the
oat flour concentrate was added to the orange and lemon ices.

Cocoa flour was found to be an effective antioxidant when added directlj' to
milk. Also cocoa flour and oat flour possessed antioxygenic properties when
used for treating paper milk-container stock.

Factors which may affect the solubility of the antioxidant oat flour in ice
cream mix and milk are being investigated. The effect of temperature of the milk
at the time the oat flour is added has been studied. No significant differences
were noted for temperatures ranging from 50° to 160° F.

The Use of Corn Syrup Solids in Ice Cream and Ices. (M. J. Mack and J. H.
Nair.) The use of dried corn s\Tup as a sweetener in frozen dairy products was
discussed in a previous publication. (Corn Syrup Solids Improve Frozen Dairy
Products. Lynn R. Glazier and Merrill J. Mack. Food Industries, June 1941,
p. 68.) The replacement of 20 to 25 percent of the sucrose ordinarily used in
ice cream by corn syrup solids was found to affect but slightly the sweetness of
the product and to improve somewhat the body and texture and melting charac-
teristics of the ice cream. Consumer acceptance of ice cream containing sucrose
and corn syrup solids seemed to be slightly greater than of that containing sucrose
as the only sweetening agent. During the first part of the study it became evident
that factors other than the sugar content of ice cream may affect the apparent
sweetness of the product. Therefore, the project is being continued to study
some of these factors.

Preliminary results indicate that the apparent sweetness of ice cream may be
affected by such factors as the source of butterfat, the ratio of fat to serum solids,



46 MASS. EXPERIMENT STATION BULLETIN 388

the mineral salts present, and the melting characteristics of the product. Other
factors are also involved, such as the serving temperature, the type of flavoring
used, and the ratio of solids to sugar in the ice cream.

A Study of New Stabilizing Materials for Ice Cream. (M. J. Mack and A. M.
Shipley.) Several new stabilizers have recently been developed and already are
used to some extent in ice cream. The stabilizer employed affects a number of
properties, such as the viscosity, titratable acidity, and whipping ability' of the
mix, and the flavor, body and texture, and melting properties of the ice cream.
The object of this investigation is to compare the effectiveness of the new stabiliz-
ers with those already known to be desirable in ice cream.

Among six stabilizers thus far observed, two were as effective as gelatin or sodium
alginate in producing mix viscosity and firmness of body in ice cream. They
allowed satisfactory whipping of the mix and permitted normal melting of the
product. The chief difficulty thus far encountered is that some of the newer
stabilizers are somewhat lacking in solubility. The work will continue with a
study of the effects of each active material employed, with the object of finding a
combination of stabilizing materials more satisfactory than those now available.

The Appearance of Melted Ice Cream. (M. J. Mack.) The melting charac-
teristics of ice cream have recently received more consideration, as is evidenced
by the fact that the new score card approved for ice cream by the American
Dairy Science Association allots 5 points to this item. Severe defects in melting
appearance usually are due to loss of stability of the casein in the ice cream, while
minor defects ma)' be due to other causes.

Slight increases in the acidity of mixes cause ice cream to appear curdy or
"whey off" when melting, if normal homogenization pressures are maintained.
Standardization of the acidity by the addition of som.e suitable alkaline material
does not injure the melting appearance in ice cream of average composition
unless the original acidity is greater than approximately 0.24 percent. The
melting characteristics are affected to a lesser degree by such factors as the com-
ponents used, the percentage composition, the methods of freezing, and so on.

A Comparison of the Electric and Vat Methods of Pasteurization. (L. D.

Lipman, J. H. Frandsen, and H. G. Lindquist.) Split batches of raw milk were
pasteurized in an electric pasteurizer at 162° for 16 seconds, and in a spray vat
at 143° for 30 minutes. The following conclusions may be drawn.

1. The reduction in vitamin C content of milk was less rapid in the electric-
pasteurized milk than in raw or vat-pasteurized milks.

2. The electric method gave better, that is less, phosphatase units than the
vat method.

3. Vat-pasteurization decreased the cream volume, while the electric method
gave the same cream line as that of the raw milk. However, the difference between
the two methods of pasteurization was so small that no definite conclusions
should be drawn as to which of the two methods results in the smaller decrease
in cream volume.

4. There was no significant difference in the efficiency of bacterial reduction
between the vat and electric methods of pasteurization. With som.e milks the
electric method seemed to show the higher percentage kill, whereas with other
milks the vat method seemed to show the higher percentage kill. A probable
explanation for this is that the types of bacteria or bacterial flora present in the
milk will affect the percentage killed by pasteurization. For example, evidence
seems to show that thermophilic bacteria are killed by the high-temperature-
short-time pasteurization but survive and may grow at vat-pasteurization tem-
peratures. The reverse seems to be true with the thermoduric types of bacteria.



ANNUAL REPORT, 1941 , 47

5. Electric-pasteurized milk became oxidized less rapidly, less frequently,
and to a lesser degree than did vat-pasteurized milk. A cooked flavor was found
more often and more pronounced in vat-pasteurized milk than in electric-pas-
teurized milk.

6. Generally it can be said that electric pasteurization (high temperature-
short time) of milk will tend to prevent development of oxidized and cooked
flavors, and such milk will have a higher flavor score than vat-pasteurized milk
at the end of 48 hours.

A Study of the Efficiency of the McCormick-Deering Cream Separator (Stand-
ardizer.) (A. M. Shipley and J. H. Frandsen.) In 1938 a report was given of a
study of the suitability and practicability of the DeLaval Multipurpose Sep-
arator. In some further work on this project, tests have been made on the McCor-
mick-Deering Cream Separator. The following results were obtained:

Before After

Sediment 9.8 9.8



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