investigation was changes tlle - Plant PhysiologyThe,gas-collecting anid analyzing apparatus is set upas shown in figoure 1. By- means of the water-level bottle the air in the funnel

GAS CONTENT OF CRANBERRIES AND POSSIBLE RELATION-SHIP OF RESPIRATORY ACTIVITY TO KEEPING QUALITY1

Wmi . B. ESSELEN, JR. AND C. R. FELLERS

(WITuI ONE FIGURE)

Introduction

This investigation was carried on to determine the changes in tlle com-positioni of the internal atmosphere and in the catalase activity of cranber-ries as affected by variety and temperature while the fruit is in storage.

Only a few papers have been published on the composition of the internlalatmiiosphere of fruits. In much of the work that was carried on 11o attemptwas made to correlate the results obtained with the keeping quality of thefruit. In this investigation the relationship betweein the experimentallydetermined keepingy quality of cranberries and the conlposition of tlle inter-nal atmosphere is noted. No previous published report on tlle compositionof the internal atmosphere of the cranberry was found.

Equipment for collecting and analyzing gas

Since the methods used by previous workers were not suitable for thisparticular investigation it was necessary to devise a method for collectingthe gas contained in the voids of cranberries. The followino method forcollecting gas from small fruit is rapid and sufficienitly aceurate for thiswN-ork.

The gas-collecting apparatus consists of a glass funiniel inverted in a1-liter beaker, containing approximately 500 cc. of water, freslhly boiled, toexpel anly dissolved gases. The sample of cranberries, approximately 70 gm.,is placed in the beaker of water and the inverted funnel is placed over thefruit. A length of rubber tubing conniects the stemii of the fuiinnel with thegas-analysis apparatus.

For the actual analysis of the gas a modification of the orioinal Orsatapparatus w\as used. This apparatus consisted of a gas-measurinig buretteamid two bubbling absorption pipettes. The first pipette, used to absorbcarbonidioxide, contains a 12 M solution of sodium hydroxide, whlile theseconid pipette used to absorb oxygen, contains an alkaline pyrooallic acidsoltution.

The,gas-collecting anid analyzing apparatus is set up as shown in figoure 1.By- means of the water-level bottle the air in the funnel is removed, anid thefuinnel and tube connecting the funnel with the Orsat apparattus are filledwith "gas-free w-ater" from the beaker. The water in the beaker is lheated

1 Contribution no. 253, Massaehusetts Agrieulttiral Experiment Station, Aniherst,\a.assaelthsetts.

Copyright (c) 2020 American Society of Plant Biologists. All rights reserved.

PLANT PHYSIOLOGY

FIG. 1. Apparatus for collecting and analyzing gas.

until all of the gas is expelled from the voids and intercellular spaces of thecranberries. This gas collects in the upper part of the funnel. As soon asthe gas is collected it is drawn into the gas-measuring burette by means ofthe water-level bottle. The gas is allowed to stand until it has come to thetemperature of the apparatus, and then its volume is determined by holdingthe water-level bottle so that the water level is the same in the bottle as inthe burette. The sample of gas is passed into the carbon dioxide absorptionpipette, and then passed back into the measuring burette. The absorptionsare continued until a constant reading is obtained in the measuring burette.The volume is read and the difference from the original volume representsthe volume of carbon dioxide contained in the sample. After the volume ofcarbon dioxide is determined, the volume of oxygen is determined in asimilar manner by bubbling the gas into the oxygen absorption pipette. Theresidual gas after the absorption of carbon dioxide and oxygen is calculatedas nitrogen. The volume of each of the gases is expressed in terms ofpercentage of total volume of gas.

ExperimentationEFFECT OF FREEZING AND SUBMERGENCE ON THE COMPOSITION OF INTERNAL

ATMOSPHERE OF CRANBERRIES

In order to determine the effect of various environmental factors on thecomposition of the internal atmosphere of cranberries, several samples of

528


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fruit were collected from a natural cranberry bog, at Millis, Massachusetts.The cranberries were of the Howes variety. Summaries of the compositionof the internal gas and the carbon dioxide-oxygen ratio, as well as the en-vironmental conditions to which each sample was subjected, are presented intable I.

Considering the carbon-dioxide ratio as indicative of the rate of respi-ration, the cranberries which were left on the vines had a much higher rateof respiration than those which had been harvested about a month earlierand placed in storage. Since a high rate of respiration is detrimental tofruit, it would seem advisable not to leave the cranberries on the vines toolong after they are mature.

TABLE IICOMPOSITION OF INTERNAL ATMOSPHERE OF EARLY BLACKS STORED AT 30 C. (37.40 F.)

No. oFP CARBONDAYS IN DETEZ- OXYGEN CARBON INIROGENOXYGEN CONDITION OF FRUITSTORAGE MINA- OXGN DIOXIDE RATIGFNOXYE ODTO RI

TIONS R(CA/02)

0 10 12.73 6.12 81.04 0.48 Good7 ....... 4 19.49 2.75 77.85 0.14

14 4 16.75 3.20 80.04 0.1926 7 11.55 2.89 85.54 0.2532. 7 16.26 4.05 79.68 0.2446 2 18.33 2.26 79.40 0.1252 2 17.78 1.71 80.50 0.09 Fruit becoming soft

and decayed74 ... 1 15.81 1.86 82.33 0.12 Fruit approximately

50% decayed84 1 15.37 5.59 79.04 0.36 Fruit approximately

50% decayed

Of the cranberries which were raked early in September, the fruit whichwas left on the bog and submerged in water had a much higher rate of respi-ration a month after picking than those cranberries which had been instorage during this time.

Of the cranberries which were left on the vines, those which were sub-merged in water showed a higher rate of respiration than those which wereabove water and in the air. It is possible to correlate these results withthose obtained by FRANKLIN (1), and also by WAKABAYASHI (9), who foundthat submergence weakened cranberries and made them more susceptible todisease and breakdown. A correlation of results indicates that the weakenedcondition of cranberries which have been submerged in water is due to the



increased rate of respiration. In cranberries which have been frosted therate of respiration is materially reduced.

COMPOSITION OF INTERNAL ATMOSPHERE AS AFFECTED BY VARIETY,TEMPERATURE, AND PERIOD OF STORAGE

In order to determine the variations in the composition of the internalatmosphere of cranberries throughout a definite storage period, and at dif-ferent temperatures, two varieties of cranberries, Early Blacks and Howes,

TABLE IIICOMPOSITION OF INTERNAL ATMOSPHERE OF EARLY BLACKS STORED AT 240 C. (75.2' F.)

No. oF CARBONDAYsINDETFa- CARBON ~~~~~DIOXIDE-DAYSID- OXYGEN O ITRoGEN OXYGEN CONDITION OF FRUIT

STORAGE MINA- DIOXIDERTITIONS (R02/02)

0.. 10 12.73 6.12 81.04 0.48 Good7 7 12.53 7.89 79.13 0.62 C

14 7 9.21 12.16 78.62 1.32 Fruit becoming soft,rot setting in

21 7 6.66 12.89 80.44 1.93 Fruit soft andshriveled

28 75..3 .10 12.02 82.86 2.35 High percentage offruit decayed andsoft

35 7 10.13 10.47 79.39 1.03 Fruit very soft40 3 11.64 7.79 80.56 0.67 Fruit very soft and

shriveled46 3 9.49 11.28 79.23 1.13 Fruit very soft and

shriveled53 3 9.97 9.32 81.40 1.00 Fruit very soft61 ...! 2 10.33 7.80 81.87 0.7568 1 7.33 10.00 82.67 1.36 Fruit shriveled and

I ~~~~dried78 1 8.59 8.59 82.82 1.00 Fruit 100%0 soft,

shriveled, rotten,and dried

were stored in a cold storage room at 30 C. and in a warm room at 240 C.Samples of the fruit were taken at weekly intervals and the internal gaswas analyzed. In order to have representative samples, cranberries weretaken from various parts of the storage container and mixed together tomake a uniform sample. All of the cranberries used in this experimentalwork came from Wareham, Massachusetts.

The results of the weekly analyses of the samples of cranberries aregiven in tables II, III, IV, and V. Results are calculated as percentage by

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PLANT PHYSIOLOGY

volume of oxygen, carbon dioxide, and nitrogen, and the carbon dioxide-oxygen ratio is given.

Discussion of resultsThe temperature of storage has a marked effect on the keeping quality

of cranberries. The Early Blacks stored at 240 C. broke down and decayedin approximately twenty days, while those stored at 3° C. remained in good

TABLE IVCOMPOSITION OF INTERNAL ATMOSPHERE OF HOWES STORED AT 30 C. (37.40 F.)

.NO. OF |CARONNo.or ~~~~~~~~~DIOXIDE-DAYS IN DETER- OXYGEN CARBON NITROGEN OXYGEN CONDITION OF FRUITSTORAGE MINA- DIOXIDE

TIONS RATIO-__________ ____ ___ (C202/O ) _ _ _ _ _ _ _ _

0.o 11 14.59 8.32 77.08 0.57 Good7 4 13.94 8.80 77.25 0.63

14 1 15.66 7.83 76.51 0.4924 3 12.42 7.98 79.71 0.6427 4 15.92 6.53 77.64 0.4137 6 13.65 9.32 77.02 0.6844 a 13.49 8.80 77.70 0.6550 3 15.57 7.24 77.18 0.4658 3 13.47 5.28 81.22 0.3976 ..... 2 10.40 6.82 82.77 0.6581 3 15.95 5.75 78.29 0.36 Fruit slightly soft87 .. 3 15.30 6.08 78.61 0.39 " " "

109 ... 2 14.94 6.63 78.42 0.44 Fruit slightly soft,otherwise in goodcondition

116 ... 1 13.43 5.97 80.60 0.44 Fruit slightly soft,otherwise in goodcondition

151 2 14.19 5.92 79.88 0.41 Fruit slightly soft,otherwise in goodcondition

159 5 15.55 5.86 78.57 0.37 Fruit slightly soft,otherwise in goodcondition

168 3 15.45 5.27 79.25 0.34 Fruit in fairly goodcondition

197 .. 3 15.49 4.79 79.71 0.31 Fruit 50 to 70%soft and unmar-ketable

condition for over three months. At a temperature of 240 C. the Howesalso broke down in approximately twenty days; and at this warm tempera-ture their keeping quality was no better than that of the Early Blacks.However, at a temperature of 30 C. the Howes remained in good conditionfor seven months.

Throughout all of the tests the internal atmosphere of the Howes hada much higher carbon dioxide content and a correspondingly lower oxygen

5-32



content than did the Early Blacks. Hence, the carbon dioxide-oxygen ratioof the Howes was considerably greater than that of the Early Blacks. Theseresults indicate that the keeping quality of cranberries may vary with thecarbon dioxide content and the carbon dioxide-oxygen ratio.

The nitrogen plus inert gas content of the internal gas of the cranberriesis similar to that of the atmosphere, about 79 per cent., except when thefruit is respiring at a very rapid rate. When the respiration rate is high

TABLE VCOMPOSITION OF INTERNAL ATMOSPHERE OF HOWES STORED AT 240 C. (75.20 F.)

No. or CARBONDAYS IN DETER- OXYGEN CARBON DINIIOGNOXYGEN ICONDIION OF FRUITSTORAGE MINA- DIOXIDE RATIO

TIONS R(aO/O2)

0 11 14.59 8.32 77.08 0.57 Good6 .. 9 7.21 13.66 79.21 1.89 Slightly soft

13 10 6.24 16.95 76.80 2.71 Fruit becoming soft21 10 5.39 17.62 76.98 3.27 Fruit quite soft, rot

setting in, un-marketable condi-tion

28 7 5.14 18.49 76.21 3.59 Softness and rot in-creasing

37 7 4.64 17.24 78.11 3.71 Large percentage offruit very soft

44 - 7 5.28 17.90 76.81 3.38 Most of fruit verysoft

50 .. 6 5.61 17.07 77.31 3.04 Most of fruit verysoft

58 .. 6 5.53 16.17 78.27 2.92 Fruit very soft66 .. 3 7.53 12.93 79.53 1.71 Fruit very soft73 .. 2 6.14 11.25 82.85 1.83 Fruiit badly shriveled80 1 5.73 11.46 82.81 2.00 Fruitindecayedcon-

dition

the increased carbon dioxide content apparently replaces some of the nitro-gen. But in general it may be said that the precentage of nitrogen in theinternal atmosphere of cranberries is quite stable. When the cranberrieshave stopped respiring, or the cells are dead, the composition of the internalatmosphere approximates that of the outside atmosphere, i.e., 79 per cent.nitrogen and 21 per cent. oxygen.

When stored at a warm temperature, the Howes showed a very rapidincrease in the carbon dioxide content and a correspondingly rapid decreaseafter the peak was reached. Under similar conditions the carbon dioxide

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PLANT PHYSIOLOGY

content of the Early Blacks showed a more gradual increase and decreaseand the peak was lower than in the Howes variety. MAGNESS (5), KIDD andWEST (4), and HARLEY and FISHER (2) obtained similar results from theirstudies on the internal atmosphere of apples.

In the cranberry there is a definite amount of respirable material whichmust be used up during respiration, before internal breakdown sets in. Ifthe fruit is stored at a high temperature this material is used up morerapidly, as is shown by the carbon dioxide-oxygen ratios. In a similarmanner it is shown that when cranberries are stored at low temperaturesthis respirable material is used up very gradually with the result that thelife of the cranberry is greatly prolonged.

It is interesting to note that the Early Blacks stored at 24° C. showed asecondary peak in the carbon dioxide content and in the carbon dioxide-oxygen ratio. This secondary peak occurred after the fruit was very softand decomposed. The odor of the cranberries made it quite evident thatfermentation was taking place within the fruit. In all probability thisincrease in the carbon dioxide content of the internal gas was due to theaction of microorganisms on the decomposed fruit.

The data obtained from these tests indicate that by a study of the carbondioxide-oxygen ratios, based on the composition of the internal atmosphereof cranberries, it is possible to determine the length of time that cranberriesmay be kept in cold storage before internal breakdown sets in, and the fruitis in an unmarketable condition. This information may be obtained byrunning a test on cranberries stored at a high temperature for approxi-mately ten days in the fall, when the fruit is first placed in storage. Bycomparing the carbon dioxide-oxygen ratios it is possible to forescast aheadapproximately how long cranberries may be kept in storage. Such a fore-cast of the keeping quality of craniberries should be of value to canneriesand people using cold storage. The writers propose also to check thismethod against the "spore load" and incubation tests for keeping qualityas described by STEVENS (8). The present studies supplement the reportson respiration in cranberries during storage by MORSE (6) and on the spoil-age of cranberries after harvest by SHEAR, STEVENS, WILCOX, and RUDOLPH(7). In general, these results are in agreement with the findings of theseinvestigators.

CATALASE ACTIVITY OF CRANBERRIES STORED AT 30 C. AND 240 C.

In conjunction with the study of the changes in the composition of theinternal atmosphere of cranberries during storage the catalase activity ofthe cranberries was determined at weekly intervals. Two methods wereused in the determination of catalase activity. The first method used wasthe potassium permanganate titration method, by which the hydrogen per-

534



oxide niot decomposed by the catalase is determinied by titrating with potas-sium permanganate. The aniount of potassium permanganate solution usedvaried iniversely with the catalase activity. This method was discontinuedbecause the tanniins and pigments present in the fruit also reduce the per-mangyanate solutioni, ancd because the results obtained are not a true indica-tion of the actual catalase activity.

The second metliod for catalase determination was very satisfactory.The principle of the method is the volumetric liberation of oxygen fromhydrogen peroxide as described by HAWK and BERGEIM (3). While cran-berries show a moderate catalase activity, there was no correlation betweencatalase and respiratory activity at 30 C. but there was a direct correlationat 240 C. In general, a hig,h catalase activity is associated with poor keep-ing quality. There is a sharp iiierease in activity a short time before cran-berries begin to show' struLctural breakdown in cold storaoe. The volume ofoxygen liberated from hydrogen in Howes or Early Black varieties storedat 3° C. varies from 2 to 4 cc., while at 240 C. this value is somewhat higher.The data were not sufficiently impressive to warrant further experimentalwork thoug,h four different lots of cranberries were examined at weeklyintervals for several months.

Summary1. Submergence cauises an increased rate of respiration in cranberries

and an increase in the carbon dioxide conitenit of the interinal atmosphere.It is probable that the increased rate of respiration weakens the cranberryand makes it more susceptible to fungus disease, as has been observed byFRANKLIN (1) anid also by WAKABAYASHI (9).

2. Frosting reduces the rate of respiration in craniberries.3. There is aii iiicrease in the respiration of craiiberries if they are left

on the vines after the usual picking time or maturity.4. The temperature of storaoe has a marked affect on the keeping quality

of cranberries. Cranberries stored at 24° C. (75.2° F.) became soft andpartially decayed withiii tweiity days.

5. The carbon dioxide conteiit anid the carbon dioxide-oxygen ratio varydirectly with the keepiiig quality of the craniberries.

6. The nitrogeii content of the internal atmosphere of cranberries isrelatively constanit and approximates that of the atmosphere. The carbondioxide and oxygen conitents of the internal gas vary wN-ith the rate ofrespiration.

7. Cranberries contain a definiite amouniit of respirable material whichmust be used up before cranberries show physical breakdowni in storage.Wheni there is a high rate of respiration these expenidable energy reservesare used up more rapidly and the life of the cranberry in storage is cor-respondingly decreased.

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8. By means of the carbon dioxide-oxygen ratio it is possible to forecastwith fairly good accuracy several months in advance the keeping qualitiesof cranberries in cold storage.

9. There is no significant correlation between catalase activity andrespiratory activity of cranberries in storage.

10. The potassium permanganate titration method for the determinationof catalase activity in cranberries is inaccurate because of interfering sub-stances which are present in the cranberry.

MASSACHUSETTS AGRICULTURAL EXPERIMENT STATIONAmHERST, MASSACHUSEWS

LITERATURE CITED

1. FRANKLIN, H. J. Report of the Cranberry Station for 1919 and 1920.Massachusetts Agr. Exp. Sta. Bull. 206. 1921.

2. HARLEY, C. P. and FISHER, D. F. A study of the internal atmosphere ofapples in relation to soft scald. Proc. Amer. Soc. Hort. Sci. 27:271-275. 1930.

3. HAWK, P. E., and BERGEIM, 0. Practical physiological chemistry. 10thed. 1931.

4. KIDD, F., and WEST, C. Brown heart. A functional disease of applesand pears. Great Britain Dept. Sci. & Ind. Res. Food Invest. Bd.Special Rpt. no. 12. 1923.

5. MAGNESS, J. R. Chemical and physiological studies on fruit storage.Proc. Amer. Soc. Hort. Sci. 18: 169-172. 1921.

6. MORSE, F. W., and JONES, C. P. Studies of cranberries during storage.Massachusetts Agr. Exp. Sta. Bull. 198. 1920.

7. SHEAR, C. L., STEVENS, N. E., WILCOX, R. B., and RUDOLPH, B. A. Spoil-age of cranberries after harvest. U. S. Dept. Agr. Bull. 714. 1918.

8. STEVENS, N. E. A method of testing the keeping quality of certain smallfruits. Phytopath. 19: 593-596. 1929.

9. WAKABAYASHI, S. The injurious effect of submergence on the cranberryplant. New Jersey Agr. Exp. Sta. Bull. 420. 1925.

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Documents

investigation was changes tlle - Plant PhysiologyThe,gas-collecting anid analyzing apparatus is set upas shown in figoure 1. By- means of the water-level bottle the air in the funnel