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CORNELL FRUIT HANDLING AND STORAGE NEWSLETTER

G. D. Blanpied, R. M. Smock, and F. W. Liu

Pomology Department, Cornell University, Ithaca, New York

July 1976

; Firmness of Mcintosh apples at harvest and when removed] from 32° air storage (November through January) and fromI CA storage (February through May).

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HARVEST NOV

iggFSDEC JAN FEB MAR APR

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32°

36°

32°

CO2C02

APPLES

"Soft" Mcintosh Problem

for CA Mcintosh

for CA Mcintosh

vs 38° for CA Macoun

treatment for Mcintosh

treatment for Delicious

Ethylene in CAIdared Softening and BreakdownTesting for OverripenessEmpire and Spartan as Mcintosh SubstitutesEarly harvest Release Dates in New YorkScald

CA EQUIPMENT

13.) Paint for Salt Blowers14.) Air trap for Water Scrubbers15.) Oxygen Burners and COn Scrubbers

NOTES

16.) CA school in 1976.

1.) The "Soft" Mcintosh Problem. In 5 of the past 7 seasons "soft" Mcintosh hasbeen a commercially significant storage problem in at least one of the majorNew York apple regions: 1969, 1970, 1971, 1973, and 1975. The incidencesof "soft" Mcintosh were alarmingly high in all 3 regions this past season.We noticed our Ithaca grown Mcintosh were softening very rapidly when removedfrom storage in December. We received the first rumblings from commercialstorages in January. They continued through June. Three other storages problems sometimes accompanied the "soft" breakdown: scald, even when DPA hadbeen used, decay, and X-injury, which we haven't seen since the mid-1950's.

In March, April, and May 1976 we collected more than 50 samples ofMcintosh from Lake Ontario, Champlain Valley, Hudson Valley, and 5 New Englandstates. Some of the samples were severely affected and others not at all affected by the "soft" problem. Tissue analyses of these samples revealed therewas no relationship between mineral composition (calcium, potash, boron, etc.)and breakdown. The incidence of breakdown was not associated with harvest

date, fruit size, or storage practice, except that holding the apples forlong periods after opening a CA room appeared to increase breakdown. In thesurvey we pinpointed a number of good and bad orchard blocks. We'll followup with leaf, fruit, and soil analyses in several of these blocks this season.

We carried out a number of experiments in an attempt to gain insight intomethods which might be used to control the disorder. The results of these experiments are summarized below.

Treatments which did influence the incidence of "soft" Mcintosh. (1.)Omission of Alar from the 1975 spray program decreased the dry, mealy texture of apples. The non-Alar trees in this experiment did receive Alar forseveral seasons prior to 1975. Alar did not influence breakdown in anotherexperiment noted in the next paragraph. (2.) DPA (1000 ppm) increased firmness 1 pound. (3.) Storage in poly box liners increased the incidence ofbreakdown.

Treatments which did not influence the incidence of "soft" Mcintosh.(1.) Partial and complete defoliation of limbs, ringing limbs, shading limbs,and summer pruning. (2.) Calcium chloride, calcium nitrate and ascorbicacid tree sprays. (3.) Omission of Alar from the orchard spray program.The non-Alar trees in this experiment had never received Alar. (4.) Calcium chloride and ascorbic acid dips before storage. (5.) Low pressurestorage for 2, 4, 6, and 8 weeks before CA. (6.) 13-15% C02 for 2, 4, 6,and 8 weeks before CA. (7.) Low, medium, and high relative humidity duringthe first 2, 4, 6, and 8 weeks of CA. (8.) 32° CA for the entire season.None of the above treatments appeared to influence the amount of "soft"breakdown.

We will continue to try to come up with some answers.

20 32° for CA Mcintosh. We tried in a number of seasons to combine Mcintoshwith Delicious to meet the requirements of small operators who want to storeall varieties in a single CA room. In the past we have observed that Delicious soften excessively at 38° and Mcintosh develop off flavors in 3% oxygen

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at 32°. This past season we used 4-5% oxygen at 32°. Mcintosh did not develop off flavors with this combination. In comparison with 37„ oxygen at 38°Mcintosh in 4-57» oxygen at 32° were the same firmness, had the same acid content and level of breakdown. However, nearly 50% of the 32° CA apples hadbrown core.

3.) 36° for CA Mcintosh. A number of operators in all 3 regions of New Yorkused 36° for CA Mcintosh this past season. We cannot recommend 36° becausewe do not have sufficient experimental data to know if it is really betterthan 38°. However, we have not heard of a single fruit storage problem associated with the use of the lower than Cornell recommended temperature whenit was used.under commercial conditions in New York, New England, Michigan,Ontario, and British Columbia.

4.) 32° vs 38° for CA Macoun. Macoun was stored in 32° and in 38° CA roomsfor 2 seasons. The results are shown below.

Firmness, taste panel ratings, and breakdown of CA Macoun

1974-75* 1975-76**

Temp, inCA room

32<

38'

32°

38°

32'

38'

(firmness - lbs)

11.1

9.4

9.8

9.0

(taste panel rating)

preferred preferred

(breakdown - %)

38 47

80 15

* averages for 2 harvest dates** averages for 3 harvest dates

32° resulted in firmer fruit, which were preferred by the taste panel, andwhich had more breakdown in one season and less breakdown in the second season.It seems that CA for Macoun may be risky.

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5.) COg Treatment for Mcintosh. We cooperated with Frank McNicholas, WarrenSmith, and Dr. Bramlage (Mass.)* Dewey (Mich.), Lougheed (Ont.), and Porritt(B.C.) to study the effect of high CO2 treatment on Mcintosh apples from 32orchards in North American Mcintosh Country. (This was one of the largestad-hoc experiments on record.) The results were clear cut for the 1975-76season. When CO2 treatment resulted in firmer apples after CA, the extentof CO2 injury was usually too high to be commercially acceptable. We willabandon further study of CO2 treatment of New York Mcintosh.

6.) CQ9 Treatment for Delicious. High CO2 treatment for Delicious looked morepromising. Firmness and taste panel ratings were significantly increasedby high CO2 treatment. We did not encounter any CO2 injury in apples from4 widely scattered orchards. Delicious which were treated with CO2 at harvest, then stored in air at 32° for 90 days, and then placed into CA foran additional 90 days were significantly softer and had lower taste panelratings than comparable apples which were held in CA 180 days without previous CO2 treatment. Double use of CA rooms is a questionable practice,even with CO2 treated apples.

7.) Ethylene in CA Storage. Ethylene in commercial CA storages is usually about500 ppm. We stored Mcintosh, Cortland, Delicious, Golden Delicious, andIdared in experimental CA chambers with 0, 10 and 500 ppm ethylene. Mcintoshpicked before the beginning of the climacteric rise in respiration (veryearly) responded to the zero ethylene treatment. They were higher in firmness, acidity, and had higher taste panel scores. In all other cases, however, there were no differences in condition of apples stored with or without ethylene.

8.) Idared Softening and Breakdown. It has been demonstrated that the severityof breakdown in this variety can be predicted by holding the apples at roomtemperature after harvest for 4-6 weeks. The amount that developed in 32°Fair storage by May 1 was comparable to that which developed at 70° after harvest.

Idared gives the impression of being a "hard" apple and it is. Yet thepressure test at harvest time may only be 15 pounds. It softens down to aplateau or flat area of about 9 pounds. The apple feels firm at this pressure test but it is mealy to the taste. See figure 1 for the effect of temperature on softening of Idared.

Breakdown of Idared is not a type of low temperature breakdown as itis in Jonathan. They break down sooner at 70°F than at 38° and sooner at38° than at 32°. CA storage delays breakdown. Changing the relative humidityaround Idared did not change the amount of breakdown.

For the first time in our trials calcium decreased the amount of breakdown. Tree sprays of calcium nitrate plus a penetrant reduced the amount ofbreakdown but they also reduced the color. This latter effect was very im-

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portant. A dip of calcium chloride reduced the amount of breakdown. Theuntreated had 62% breakdown and the treated had only 8%. The problem stillseems to be one mainly of large fruit from younger trees. Such fruit shouldbe sold early.

9.) Testing for Overripeness. We studied the relationship between pressure testreadings and a taste panel's opinion of whether or not various lots of appleswere overripe. In each of 3 seasons we used 3 harvest dates for each of thefollowing: Mcintosh, Delicious, Golden Delicious, Idared, Rome. The resultsof this study precluded the possibility of writing minimum pressure testvalues into the apple grading regulations. Many of the lots scored as overripe by the panel were firmer than lots of the same variety which were notscored as overripe. Unfortunately, we still must rely on taste, appearance,and experience to determine if a lot of apples is overripe and thereforeout of grade.

10.) Empire and Spartan as Mcintosh Substitutes. Our tests of Empire and Spartanas Mcintosh substitutes are extremely limited but the preliminary resultsare of sufficient interest to recount here. Mcintosh, Spartan, and Empireapples were harvested on September 18, 25, and October 2 from trees at theGeneva experiment station. On each harvest date the fruits of the 3 varietieshad almost equal red color. In November 50 uniform Mcintosh, Empire, andSpartan apples were selected from the first harvest date. Fifty customersat our retail outlet were presented with one apple of each variety. Thevarieties were not identified. They were asked to look at the 3 fruits,and taste them, and express a preference for one of the three. This procedure was repeated for apples from the second and third harvest dates.The whole procedure was again repeated in January and in March (CA). Theresults are summarized below. We lumped together the data for the 3 harvest dates because there were no real differences due to harvest date.

Customers' preference for Mcintosh, Spartan, or Empire(averages for 3 harvest dates.)

Month of

survey Mcintosh Spartan Empire

(7o of customers preferring each variety)

November 14 58 28

January 12 42 46

March 10 34 56

Only 10 to 147o of the customers preferred Mcintosh. Spartan scoredhighest in November and Empire scored highest in March. This preliminarystudy indicated Spartan and Empire picked during the normal Mcintosh harvest season were preferred to Mcintosh picked on the same dates.

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11.) Early Harvest Release Dates in New York. We conducted a statewide study ofoptimum harvest dates for storage Mcintosh during 9 seasons in the 1960'sThe information from this study has been used each subsequent season to forecast optimum harvest dates for Mcintosh in the Hudson Valley, Champlain Valley,and in the Lake Ontario fruit regions. The forecasts are based on the dateof bloom and the temperatures which prevail during the first 30 days afterbloom.

In 1975 we completed a six year study of methods for setting earliestacceptable harvest dates for Delicious. We found the ability of Deliciousto ripen with acceptable eating quality was related to the firmness andsoluble solids at harvest.

The knowledge gained from these 2 large studies will be used in Albanyby the industry represented apple maturity committee, which will set the earlyharvest release dates for the most important fresh market apple varieties ineach of the 3 New York apple regions.

12.) Scald. Several years ago a glossy advertisement appeared which stated thatone brand of ethoxyquin was better than all other brands. It was also claimedthat their material was better than diphenylamine in scald control. Two years'work at Cornell have not indicated that this was true with varieties likeGreening, Cortland and Baldwin which are very scald susceptible. It wouldseem that DPA is still the superior material for varieties (except for Goldens)in a bad scald year. See our new set of scald recommendations, which is included with this newsletter.

13.) Paint for Salt Blowers. From time to time we have reported on various paintswhich held up well under the severe conditions encountered when salt is usedin the water scrubber. Here is another good recipe: 2 coats of Rustoleum#769 - Damp Proof Red Primer, then a finish coat of Rustoleum #470 -Aluminum.

14.) Air Trap for Water Scrubber. If your CA room has a water scrubber and youare unable to hold the room at 2.5-3.07,, oxygen, examine the water dischargingfrom the room to be certain it is not carrying bubbles of atmosphere fromyour CA room into the machine room. If your return line is carrying atmosphere from the CA room, you may be certain air is leaking into the CA roomto replace those bubbles. In last year's Newsletter there was a drawing ofa trap commonly used to prevent gravity returns from carrying atmosphere outof CA rooms. Last winter George Burrell found a gravity return was siphoningbubbles of atmosphere out of one of his CA rooms. When the water flow wasvalved down to eliminate the siphoning action, the CO2 went up in the CAroom. He solved the problem with a scheme similar to the one shown below.

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CA atmosphere returnedto CA room

_ Gravity return fromblower (water + CAatmosphere)

20 gallon pail

Scrubber tank

(Pump, water aerator, and CO2 absorber arenot shown in diagram.)

15.) Oxygen Burners and CO2 Scrubbers. We have received a number of requests forsources of commercially made oxygen burners and CO2 scrubbers. For your files,here are a few.

Recirculation (catalytic) oxygen burners and also carbon CO2 scrubbers:Daub Engineering Co., P. 0. Box 2080, Falls Church, VA 22042 (703-534-5978);Sulzer Bros., Inc., 19 Rector Street, NYC, NY 10006 (212-425-4560). Singlepass (open flame) oxygen burners can be purchased from Anderson Tool andMachine Co., Rockford, MI 49341 (616-874-7844).

16.) CA School in 1976. We will hold a 1-day school for new CA operators on August30. We will discuss operation of the CA room in the AM and have a gas analysislab in the FM. Tell us or your county agent if you want to attend. We willtell you the location for the school when we know who will be there.