i::: :;.i; :::: CORNELL FRUIT HANDLING AND STORAGE NEWSLETTER G. D. Blanpied, R. M. Smock, and F. W. Liu

Transcription

1 1 ;ti:!::: i::: m :;.i; :::: CORNELL FRUIT HANDLING AND STORAGE NEWSLETTER Hi mm ati : G. D. Blanpied, R. M. Smock, and F. W. Liu Pomology Department, Cornell University, Ithaca, New York July i 14 SO.J 12 R CO CO H rd CO HARVEST ; Firmness of Mcintosh apples at harvest and when removed ] from 32 air storage (November through January) and from I CA storage (February through May). NOV iggfs DEC JAN FEB MAR APR +f - MAY

2 APPLES The CO2 "Soft" Mcintosh Problem for CA Mcintosh for CA Mcintosh vs 38 for CA Macoun treatment for Mcintosh C02 treatment for Delicious Ethylene in CA Idared Softening and Breakdown Testing for Overripeness Empire and Spartan as Mcintosh Substitutes Early harvest Release Dates in New York Scald CA EQUIPMENT 13.) Paint for Salt Blowers 14.) Air trap for Water Scrubbers 15.) Oxygen Burners and COn Scrubbers NOTES 16.) CA school in 1976.

3 1.) The "Soft" Mcintosh Problem. In 5 of the past 7 seasons "soft" Mcintosh has been a commercially significant storage problem in at least one of the major New York apple regions: 1969, 1970, 1971, 1973, and The incidences of "soft" Mcintosh were alarmingly high in all 3 regions this past season. We noticed our Ithaca grown Mcintosh were softening very rapidly when removed from storage in December. We received the first rumblings from commercial storages in January. They continued through June. Three other storages prob lems sometimes accompanied the "soft" breakdown: scald, even when DPA had been 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 of Mcintosh from Lake Ontario, Champlain Valley, Hudson Valley, and 5 New England states. Some of the samples were severely affected and others not at all af fected by the "soft" problem. Tissue analyses of these samples revealed there was 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 for long periods after opening a CA room appeared to increase breakdown. In the survey we pinpointed a number of good and bad orchard blocks. We'll follow up 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 into methods which might be used to control the disorder. The results of these ex periments 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 tex ture of apples. The non-alar trees in this experiment did receive Alar for several seasons prior to Alar did not influence breakdown in another experiment noted in the next paragraph. (2.) DPA (1000 ppm) increased firm ness 1 pound. (3.) Storage in poly box liners increased the incidence of breakdown. 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 ascorbic acid tree sprays. (3.) Omission of Alar from the orchard spray program. The non-alar trees in this experiment had never received Alar. (4.) Cal cium chloride and ascorbic acid dips before storage. (5.) Low pressure storage 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 during the 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 for CA Mcintosh. We tried in a number of seasons to combine Mcintosh with Delicious to meet the requirements of small operators who want to store all varieties in a single CA room. In the past we have observed that Deli cious soften excessively at 38 and Mcintosh develop off flavors in 3% oxygen

4 -2- at 32. This past season we used 4-5% oxygen at 32. Mcintosh did not de velop 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 con tent and level of breakdown. However, nearly 50% of the 32 CA apples had brown core. 3.) 36 for CA Mcintosh. A number of operators in all 3 regions of New York used 36 for CA Mcintosh this past season. We cannot recommend 36 because we do not have sufficient experimental data to know if it is really better than 38. However, we have not heard of a single fruit storage problem as sociated with the use of the lower than Cornell recommended temperature when it 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 rooms for 2 seasons. The results are shown below. Firmness, taste panel ratings, and breakdown of CA Macoun Temp, in CA room * ** (firmness - lbs) 32< 38' (taste panel rating) preferred preferred (breakdown - %) 32' 38' * averages for 2 harvest dates ** averages for 3 harvest dates 32 resulted in firmer fruit, which were preferred by the taste panel, and which had more breakdown in one season and less breakdown in the second season. It seems that CA for Macoun may be risky.

5 -3-5.) COg Treatment for Mcintosh. We cooperated with Frank McNicholas, Warren Smith, and Dr. Bramlage (Mass.)* Dewey (Mich.), Lougheed (Ont.), and Porritt (B.C.) to study the effect of high CO2 treatment on Mcintosh apples from 32 orchards in North American Mcintosh Country. (This was one of the largest ad-hoc experiments on record.) The results were clear cut for the season. When CO2 treatment resulted in firmer apples after CA, the extent of CO2 injury was usually too high to be commercially acceptable. We will abandon further study of CO2 treatment of New York Mcintosh. 6.) CQ9 Treatment for Delicious. High CO2 treatment for Delicious looked more promising. Firmness and taste panel ratings were significantly increased by high CO2 treatment. We did not encounter any CO2 injury in apples from 4 widely scattered orchards. Delicious which were treated with CO2 at har vest, then stored in air at 32 for 90 days, and then placed into CA for an additional 90 days were significantly softer and had lower taste panel ratings than comparable apples which were held in CA 180 days without pre vious 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 about 500 ppm. We stored Mcintosh, Cortland, Delicious, Golden Delicious, and Idared in experimental CA chambers with 0, 10 and 500 ppm ethylene. Mcintosh picked before the beginning of the climacteric rise in respiration (very early) responded to the zero ethylene treatment. They were higher in firm ness, acidity, and had higher taste panel scores. In all other cases, how ever, there were no differences in condition of apples stored with or with out ethylene. 8.) Idared Softening and Breakdown. It has been demonstrated that the severity of breakdown in this variety can be predicted by holding the apples at room temperature after harvest for 4-6 weeks. The amount that developed in 32 F air storage by May 1 was comparable to that which developed at 70 after har vest. Idared gives the impression of being a "hard" apple and it is. Yet the pressure test at harvest time may only be 15 pounds. It softens down to a plateau or flat area of about 9 pounds. The apple feels firm at this pres sure test but it is mealy to the taste. See figure 1 for the effect of tem perature on softening of Idared. Breakdown of Idared is not a type of low temperature breakdown as it is in Jonathan. They break down sooner at 70 F than at 38 and sooner at 38 than at 32. CA storage delays breakdown. Changing the relative humidity around Idared did not change the amount of breakdown. For the first time in our trials calcium decreased the amount of break down. Tree sprays of calcium nitrate plus a penetrant reduced the amount of breakdown but they also reduced the color. This latter effect was very im-

6 14' 13- *»t.( v #», '»t. "»#,o. IDARED SOFTENING s 12- en 11* 7<f ft V N 32" ".. V V '** v Ul Z 2 oc E 9- * ^ -«* *,.,«. '*.,..,*.,»»<V trnma,»». "». '.'»,. *.. 8 < T 2 3 T 5 MONTHS Figure 1. Softening of Idared apples held at various temperatures,

7 -4- portant. A dip of calcium chloride reduced the amount of breakdown. The untreated had 62% breakdown and the treated had only 8%. seems to be one mainly of large fruit from younger trees. be sold early. The problem still Such fruit should 9.) Testing for Overripeness. We studied the relationship between pressure test readings and a taste panel's opinion of whether or not various lots of apples were overripe. In each of 3 seasons we used 3 harvest dates for each of the following: Mcintosh, Delicious, Golden Delicious, Idared, Rome. The results of this study precluded the possibility of writing minimum pressure test values into the apple grading regulations. Many of the lots scored as over ripe by the panel were firmer than lots of the same variety which were not scored as overripe. Unfortunately, we still must rely on taste, appearance, and experience to determine if a lot of apples is overripe and therefore out of grade. 10.) Empire and Spartan as Mcintosh Substitutes. Our tests of Empire and Spartan as Mcintosh substitutes are extremely limited but the preliminary results are of sufficient interest to recount here. Mcintosh, Spartan, and Empire apples were harvested on September 18, 25, and October 2 from trees at the Geneva experiment station. On each harvest date the fruits of the 3 varieties had almost equal red color. In November 50 uniform Mcintosh, Empire, and Spartan apples were selected from the first harvest date. Fifty customers at our retail outlet were presented with one apple of each variety. The varieties 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 pro cedure was repeated for apples from the second and third harvest dates. The whole procedure was again repeated in January and in March (CA). The results are summarized below. We lumped together the data for the 3 har vest 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 January March Only 10 to 147o of the customers preferred Mcintosh. Spartan scored highest in November and Empire scored highest in March. This preliminary study indicated Spartan and Empire picked during the normal Mcintosh har vest season were preferred to Mcintosh picked on the same dates.

8 -5-11.) Early Harvest Release Dates in New York. We conducted a statewide study of optimum harvest dates for storage Mcintosh during 9 seasons in the 1960's The information from this study has been used each subsequent season to fore cast optimum harvest dates for Mcintosh in the Hudson Valley, Champlain Valley, and in the Lake Ontario fruit regions. The forecasts are based on the date of bloom and the temperatures which prevail during the first 30 days after bloom. In 1975 we completed a six year study of methods for setting earliest acceptable harvest dates for Delicious. We found the ability of Delicious to ripen with acceptable eating quality was related to the firmness and soluble solids at harvest. The knowledge gained from these 2 large studies will be used in Albany by the industry represented apple maturity committee, which will set the early harvest release dates for the most important fresh market apple varieties in each of the 3 New York apple regions. 12.) Scald. Several years ago a glossy advertisement appeared which stated that one brand of ethoxyquin was better than all other brands. It was also claimed that their material was better than diphenylamine in scald control. Two years' work at Cornell have not indicated that this was true with varieties like Greening, Cortland and Baldwin which are very scald susceptible. It would seem 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 in cluded with this newsletter. 13.) Paint for Salt Blowers. From time to time we have reported on various paints which held up well under the severe conditions encountered when salt is used in 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 you are unable to hold the room at ,, oxygen, examine the water discharging from the room to be certain it is not carrying bubbles of atmosphere from your CA room into the machine room. If your return line is carrying atmos phere from the CA room, you may be certain air is leaking into the CA room to replace those bubbles. In last year's Newsletter there was a drawing of a trap commonly used to prevent gravity returns from carrying atmosphere out of CA rooms. Last winter George Burrell found a gravity return was siphoning bubbles of atmosphere out of one of his CA rooms. When the water flow was valved down to eliminate the siphoning action, the CO2 went up in the CA room. He solved the problem with a scheme similar to the one shown below.

9 -6- CA atmosphere returned _ to CA room 20 gallon pail Gravity return from blower (water + CA atmosphere) VVPZm Scrubber tank (Pump, water aerator, and CO2 absorber are not shown in diagram.) 15.) Oxygen Burners and CO2 Scrubbers. We have received a number of requests for sources 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 ( ); Sulzer Bros., Inc., 19 Rector Street, NYC, NY ( ). Single pass (open flame) oxygen burners can be purchased from Anderson Tool and Machine Co., Rockford, MI ( ). 16.) CA School in We will hold a 1-day school for new CA operators on August 30. We will discuss operation of the CA room in the AM and have a gas analysis lab in the FM. Tell us or your county agent if you want to attend. We will tell you the location for the school when we know who will be there.