FRUIT COOL STORAGE.

New Zealand Journal of Agriculture, Volume XXII, Issue 1, 20 January 1921, Page 25

FRUIT COOL STORAGE.

HANDLING EXPERIMENTS IN 1920 SEASON.

W. H. RICE,

Orchard Instructor, Hastings.

During the season of 1919 the Horticulture Division carried out in Hawke’s Bay comprehensive experiments in the picking, handling, and packing of apples and pears for cool storage, concerning which a report was published in the Journal for January, 1920. The experiments were continued last year, and the matter which follows should be read as supplementary to the previous report. The 1920 experiments were designed to specially test the following points : (1) The best stage of maturity at which to pick fruit for successful cool storage ; (2) • the value of wrapping against non-wrapping of fruits prior to storage ; (3) the effect of russeting on the value of fruit for storage ; (4) methods of handling: grading and packing in the —wrapped and unwrapped grading in the orchard, conveying the fruit in orchard cases to the store, and then packing before storage.

STAGE OF MATURITY AT WHICH TO PICK APPLES.

Eight varieties of apples and three varieties of pears were used for this test. As the cases were made with newly cut timber, it was found impracticable to check the loss of weight during storage. All dates apply to 1920.

(1.) Cox’s Orange Pippin. — Two pickings were made, on 23rd February and 2nd March. The fruit picked on each date was graded into two stages of maturity. The fruit was removed from store and examined on 14th June.

(«.) First picking : Had a well-defined . yellowish ground colour, with blush and stripe. On removal, from store this fruit was in excellent condition, but ripened rapidly and became soft-ripe in ten days. Duplicate cases in each instance showed that wrapped fruit was riper and brighter in appearance. (S.) First. picking : Just on change .to light yellow in base colour, with light blush. This fruit stored well and ripened up well, with defined yellow ; very attractive, though only about 10 per cent, of colour. Ripened more slowly than (a) after removal from store ; still in good marketable condition twenty-one days after removal. (c.) Second . picking : Yellow ; stripe and blush dull. Behaved in a similar manner to (a) under storage, but became dry and mealyfleshed seven days out of store.

Second picking : Greenish-dull, little or no colour ; firm when removed from store, and only attained low and unattractive colour except wrapped, which was brighter and riper. Shrinkage was rapid and pronounced when held ten days out of store. The indications are that base colour is the factor which should govern picking —more so than blush —to secure best results. Fruits should be picked when the green base colour is inclined to yellow ; if

allowed to remain on trees to colour up, although more attractive at picking-time, the storage period is shortened, and also the period of marketing.

(2.) Dunn’s (Monroe’s Favourite). Two pickings were made, on 25th February and sth March, and the fruit graded into two stages of maturity on each date. Removed from store sth July. (a.) First picking : Well-developed fruits as to size ; only very slight change of ground colour, with light blush. When removed from store, firm and greenish, unattractive, inclined to shrink, and became very spongy and wrinkled in skin fourteen days after withdrawal. Wrapped fruits no improvement. (&.) First picking: Though well up to size, no change of ground colour. When removed from store were limp and green; did not ripen, but shrivelled very rapidly. Wrapped fruits similar, except more brilliant green. (c.) Second picking : Well-defined yellowish ground colour, regardless of . blush. When removed from store very attractive, firm; ripened well and kept well out of store, conditioning gradually with •no shrinkage. Wrapped fruits brighter, cleaner, and more refined skin-texture.

((/.) Second picking : Green ground colour, with good blush (highcoloured fruits with basal colour undeveloped). When removed from store there was little or no development of ground colour, which remained green, and though in contrast with a good blush the sample was not nearly so attractive as the yellow and light blush fruits of (c). Wrapping in no way improved the condition or affected the skin wrinkle and shrivel, which was pronounced at fourteen days.

The indications are that, whenever picked, ground colour should be present if fruits are to ripen under or after storage in anything like good condition with attractive appearance. Yet if the ground colour is a very pronounced yellowish-white, there is a risk of dryness and mealiness of fruit under storage.

(3-) Jonathan. — Two pickings were made, on 4th and 12th March, each picking being divided into two grades of maturity. Removed from store 15th June.

{a) First picking: Well-defined yellowish ground colour, with good blush. Excellent order when checked ; firm, nice-conditioned fruit, very attractive, especially when wrapped, which added brilliancy to the skin. Remained in good marketable condition up to twentyone days.

(6.) First picking : Greenish ground colour, with medium blush. When removed, very moderate condition, firm, greenish and dull, inclined to skin-wrinkle ten days after removal. Wrapping no appreciable improvement.

(c.) Second picking : Similar fruits to («), but eight days more advanced. When removed, equal in immediate condition to (a), except riper and more subject to bruise ; inclined to be mealy and dry after fourteen days,, particularly wrapped fruits.

(d.) Second picking : Similar fruits to (Z>), but eight days riper, and showing pronounced yellow tinge on ground. Conditioned up in good order, yellow and inclined to be mealy; ripened very rapidly on removal, being soft-ripe in fourteen days.

(e.) Various grades of maturity and russet : In all cases this fruit shrank under storage. Well-coloured fruits became soft and pliable, while greenish fruits were leathery. Comparisons indicate that well-coloured fruits should be picked only when ground colour is showing a defined yellowish tinge, otherwise the shrinkage of green parts is bad. Fully developed fruits with apparent change to yellow in base should not be allowed to hang on tree to attain blush if maximum keeping is desired, as such fruits are inclined to be soft and mushy after removal. Russeted fruits should be disposed of before shrinkage, and to facilitate this should be stored in separate cases.

(4.) Lord Wolseley. Two pickings were made, on 15th and 24th March, and each separated according to maturity. Removed from store 14th June.

(a.) First picking : Well-developed white to yellow ground colour, and left the spur freely. Removal showed these fruits to be well selected, firm, well conditioned, bright and attractive; conditioning gradually after storage, with no shrinkage up to twenty-one days. Wrapped fruits brighter and riper, but not to mealiness. (&.) First picking : Greenish colour, with only light suffusion of white to yellow. When removed firm, no colour-development," very dull compared to (a) ; no improvement wrapped. Inclined to skinwrinkle fourteen days out of store ; firm up to seven days. Five per cent, of bitter-pit noticed in this section only. (c.) Second picking : Similar to but seven days riper than (a) ; decided yellow. When removed equal to (a) in appearance ; considerably more liable to bruise, and conditioned rapidly within seven days. Mealy-overripe after fourteen days. (d.) Second picking : Green though full grown. When removed dull green, except wrapped fruits, which were bright green. Did not take on yellow ground colour prior to shrinkage ; leathery condition within fourteen days. The results indicate fruits should be picked with well-developed whitish colour to yellow tinge. When left on trees to advanced riper stage bruise more readily, do not allow such a reasonable marketingperiod, and inclined to be mealy. Fruits with undeveloped colour when picked shrink rapidly after storage, thus demonstrating that the varying maturities should be stored separately to get best results. More se 1 ection required than with most varieties to get all at correct stage.

(5.) Delicious. — Two pickings were made, on 16th and 23rd March, each being divided into two stages of maturity. Removed from store 3rd August.

(a.') First picking : Definite change of ground colour to yellow, with good bright blush ; picked readily. Removal showed these fruits in good condition, firm, crisp, and bright-coloured ; kept well after storage, remaining full-flavoured and in excellent marketing condition up to twenty-one days. (b.) First picking : Only light tinge of yellow in ground colour, with dull blush. When removed, firm, crisp, good condition, but not so attractive as more advanced when picked. Green had taken on a light yellow, but when conditioned was inclined to toughness. (c.) Second picking: Similar, yet seven days riper than (a). Decided yellow ground, with, full blush. Removed from store as (a),

but more advanced ripeness and decidedly more subject to bruise. Conditioned to overripeness within fourteen days from store. '■ (d.) Second picking Similar to (&) but seven days riper. Welladvanced yellow ground, but only light blush. Conditioned rapidly after storage ; inclined to be mealy, though bright yellow and crisp when removed. Brighter colour and advanced ripeness due to wrapping. Results indicate that the fruit should be picked when ground colour is well defined, regardless of blush. Fruits left to advanced maturity on tree do not store so well, are more subject to bruise, and do not allow same latitude of disposal. Uncoloured (blush) fruits should also be picked when ready, and may then be expected to mature gradually in good order, though not high-coloured.

(6.) Sturmer. — Two pickings were made, on 30th March and 7th April. Removed from store 23rd September. (a.) First picking: Well-defined light-yellow change of ground colour, with traces of leaf-green. When removed from store proved firm and crisp, and kept well, conditioning very gradually. . (J.) First picking : Good bright blush, but basal colour still green. When removed from store, still green and firm, but developed a flexible condition ; instead of ripening became limp and tough-fleshed in twentyone days.

(c.) Second picking : Similar fruits but seven days riper than (a). Meanwhile had developed a pronounced yellow ground. When removed from store, bright, firm, crisp, and rather dry. Very attractive appearance, but bruised readily, this showing up very distinctly, and rapidly decayed. Limited marketing-period, as most fruits proved mealy, in fourteen days. (d.) Second picking: Spray-russeted fruits in various grades of maturity and blush. When removed from store it was found that shrivelling had taken place in all fruits. The worst specimens were those of low maturity, then those of reasonable maturity with confluent russet, and to a much lesser extent, but still sufficient to affect the condition of the fruit, those specimens on which russet was scattered over the surface.

The results indicate that change of ground colour should be present when picked, and that all fruits should be packed separately, according to maturity. 5 per cent, of confluent russet is more damaging to the ultimate condition of the fruit than 10 per cent, scattered.

(7.) McMahon’s White. — These fruits were graded, packed, and cooled-stored on 20th April from fruits picked on 14th April, and held in the fruit-shed at Arataki Horticultural Station. Removed from store on 7th September.

(a.) Well-developed yellow ground colour, with mixed blush. When removed from store, firm but dry and mealy. Examination from time to time in store showed that this fruit was in the best-quality marketing condition in the early part of August. (&.) Light change of ground colour with mixed blush and traces of leaf-green showing. When removed from store this fruit was in excellent condition, and remained so for twenty-one days. Fruits allowed to remain in store attained their maximum fair marketing condition by mid-November. (c.) Mixed maturity with spray russet, and all grades of blush. When removed from store all fruits had shrivelled according to the degree

of russet. Shrinkage was more pronounced where russet was confluent ; with specimens well matured it was only such parts that shrivelled ; scattered russet up to 10 per cent, caused no material defect. This variety should fill a place between Delicious and Sturmer, and thus prolong the season for consumers who have a preference for apples of the Delicious flavour.

(8.) Dougherty. —Two pickings were made, on 19th and 25th May, and graded for maturity. Removed from store 26th November. ~ •

(a.) First picking : Well-coloured fruits, with leaf-green replaced by light yellow. When removed from store proved in excellent condition and in no way deteriorated in fourteen days. (&.) First and second picking : Well-coloured fruits, with leaf-green unchanged. When removed from store were firm, crisp, and juicy, but did not ripen well, becoming rather dry and pliable in fourteen days. (c.) Second picking : Well-coloured fruits, with advanced yellow in contrast. When removed from store were firm, crisp, dry, and below full flavour of the variety. Remained firm but dry and mealy, with rapid decay where injured by handling or in transit.

(th) Spray-russeted fruits of various grades of maturity. When removed from store shrivel was only apparent in fruits of low maturity. When compared to (&) this would suggest that russet was the cause of more shrinkage than undermaturity, except in the case of very pronounced undermaturity. In the course of fourteen days the ill effects due to russet became very apparent—shrivelling in the instances of heavy and confluent russet, and skin-wrinkle of fruits with moderate scattered russet.

This variety, like others, gave the best results when picked with a distinct change from leaf-green to yellow of the ground colour. The results would also suggest that much of the mealy condition so common in this variety when stored is due to it being allowed to hang on the trees regardless of advancing maturity.

Pears.

(i.) Bcurve Diet. Two pickings were made, on 9th and 15th March, and divided into two grades of maturity. Removed from store 9th June. (a.) First picking : Very slight change of ground colour, but picked readily. Proved on removal from store to be bright, well-coloured, firm, crisp fruit. Wrapped fruits brighter but not riper ;■ no inclination to shrivel or mush.

(&.) First picking : No change of ground colour, but left spur readily. When removed were bright and greenish, otherwise equal to (#.). Musty odour in all wrapped fruits, which affected flavour. (c.) Second picking : Picked readily. About equal to (a) ; more advanced not possible, as all fruits left to yellow fall to the ground. When removed from store were nice bright, well-coloured fruits, firm, crisp, and equal to (a). Musty when wrapped.

Second picking : Inside fruits not so mature and harder to pick. When removed were greenish and hard, shrinking to leathery condition instead of ripening. Results indicate that fruits should be picked when easy to sever from tree. Greenish fruits should be avoided for storage. Wrapping gives brighter colour and somewhat retards ripening, but gives musty odour, which was not noticeable with other varieties tested.

(2.) Winter —Two pickings were made, on 18th and 26th March,, and each graded to two stages of maturity. Removed from store 21st June.

(«.) First picking : Well-defined yellowish colour ; picked readily. Removed from store in splendid condition, firm, bright, well coloured, and conditioning gradually after removal. Wrapping delayed ripening but added lustre to the skin.

(b.) First picking : Greenish ground, yet picked readily. When removed fruits were firm, crisp, and not so well coloured as (<z), and took longer to condition ; were not full-flavoured, and greener fruits shrunk at the stem end.

(c.) Second picking: Similar fruits eight days riper than (a). Distinct yellow. At removal equal to («) ; ripened much more rapidly after, and. fruits bruised more readily. (d.) Second picking : Greenish to yellow ; picked readily. , Stored in splendid order ; firm, bright, crisp, and well coloured ; same fruit as (&) eight days riper. Has well demonstrated the value of leaving to more maturity on tree. Results indicate uniformity of storage if ground colour is used as a guide. Greener fruits should be allowed to remain to change base colour. Wrapping delayed ripening.

(3-) Winter Nelis. —-Two pickings were made, on 9th and 16th April, with each graded into two grades of maturity. Removed from store 6th August.

(0.) First picking: Changing to yellow, well defined but not advanced. When removed from store were well coloured, firm, crisp, and full-flavoured. Conditioning evenly and slowly with good market-ing-period ; nice condition up to twenty-one days. (&.) First picking : Greenish,, slight tinge of yellow only. When removed from store, greenish and soft; very unattractive, limp and soft after seven days. (c.) Second picking: Well-defined yellow ground; picked very readily. Seven days riper than (a). On removal from store were ripe and juicy, being ready to use immediately; bruised badly, indicating ripening on tree and shortening of storage period advisable ; should be stored separately and marketed earlier. (at) Second picking: Greenish; hard to sever from tree. On removal from store were greenish, soft, and pliable ; did not mature after storage, but shrunk to a limp condition in fourteen days. The results indicate that several pickings (selections) are necessary to catch this variety in good order. Fruits must be graded into separate cases according to maturity, prior to storage, if the various classes are to be marketed in proper season.

Summary.

The experiment just detailed indicates that there is a certain stage of maturity which allows the best results to be obtained, that stage being indicated by a distinct change of ground colour towards light yellow from leaf-green. Fruits picked which had no change of ground or basal colour proved not only to shrink under storage, but were unsuitable fruits to condition after removal, being inclined to shrink dry and leathery rather than ripen. On the other hand, fruits which were of an advanced yellowish ground colour proved mealy when stored

for the average period of the variety, and mush-ripe very soon after. The lesson to be learned is that fruit should be picked when there is a distinct change of ground colour, regardless of the high colour or blush.

With the fruits graded according to standard colour requirements when packed it was noticeable that there was no further development in intensity of high colour, but the development of ground colour provided a contrast which improved the appearance of the fruit.

With the yellow or green varieties close observation shows that the leaf-green passes through a whitish shade before turning yellow. The stage when this whitish-yellow is the dominant ground colour proved the best for picking such varieties.

Evidence goes to show that leaving fruit on the trees to attain a high colour, or blush after the change of ground colour results in speedy ripening under storage, with a consequent shorter storage period and fruit which lacks that desirable crisp and juicy quality. Such fruit is practically ripe when removed from the trees, and ready for immediate sale in the case of early and mid - season varieties. If in the case of later keeping varieties this condition of ripeness is unavoidable, such advanced fruits should be stored in separate cases to permit withdrawal from the store while still in good condition.

Beurre Diel pear presents a somewhat difficult proposition regarding the best stage at which to pick. Fruits leave the spur readily, and many fall before there is any colour to- indicate approaching maturity.

Pip-colour development gave such a wide variation throughout the test that it appears to be of little assistance in selecting the stage at which to pick for storage.

WRAPPING FRUIT PRIOR TO STORAGE.

There, were six classes of wrapped fruit, comparable with fruit similar in all respects but not wrapped : (i) Fruits with greenish ground colour packed in orchard ; (2) fruits with greenish ground colour packed in store ; (3) fruit with leaf-green changed to yellow packed in orchard ; (4) fruit with leaf-green changed to yellow packed in store ; (5) fruits with well-advanced ground colour packed in orchard ; (6) fruits with well-advanced ground colour packed in store. Results were noted as follows :-

Apples.

(1) and (2). Wrapping was no improvement on unwrapped in anyway.

(3.) Wrapped fruit had a brighter general appearance, and, though slightly riper, still retained firmness of texture. Though there was some improvement due to wrapping, there was not sufficient to warrant the extra expense for local storage, except with fruits of a special character, such as show fruits.

(4.) Similar to (3), with the added advantage which wrapping gave by confining the spread of decay to specimens injured at picking-time and in transit to the store.

(5.) Wrapping was a disadvantage in so far that it further hastened ripening.

(6.) Similar to (5), except that spread of decay was restricted.

Pears.

(i) and (2). Wrapping caused a still more shrivelled and leathery condition, particularly from the stem end. (3.) Wrapping gave a brighter skin and somewhat retarded ripening., (4.) As (3), with spread of decay confined to injured specimens. (5.) Wrapping was an advantage by delaying ripening, but not sufficient to recommend commercial usage for local market, except perhaps with Winter Cole well advanced when picked. (6.) As (5), with decay localized by wrapping. These remarks do not apply to Beurre Di el, as wrapped fruits of this variety in every instance developed a pronounced musty-wine odour, the flavour also being tainted musty.

SPRAY-RUSSETED FRUIT.

Spray-russeted fruits of each maturity were selected and packed separately. Various degrees of russeting were noted, as also was the confluent or scattered nature of the skin-injury. The effect of russet on the storage period was very marked. In all grades of maturity there was a decided shrivelling of the fruit, general with' fruits inclined to undermaturity, and confined to the russeted portion in the case of more advanced fruits.

Fruits which were good in every way but for russet exceeding 5 per cent, if confluent and 15 per cent, if scattered shrivelled badly at the russeted portion, while the clear-skin section of the same specimen would be quite firm when subjected to the normal storage period of the variety. As russeted fruits remain firm a very limited time only when coolstored, they are best stored in separate cases, so that they may be removed while still of some value.

It was very clear that russeted and clear-skinned fruits of the same variety have two distinct storage periods if each are to be marketed to the best advantage.

HANDLING TEST : PACKING IN ORCHARD VERSUS PACKING IN STORE

The handling tests consisted of testing the methods (1) and (2) specified below—namely, packing the cases in a compact manner prior to cartage, which gave such good results in the previous experiment —against (3), the usual local practice of carting fruit to the store loosely emptied into cases. The fruits were picked carefully in the usual way into a picking-bag and emptied on to a portable grading-table with canvas bottom, the table being placed in the shade. The fruit was then graded for quality and maturity and treated as under :

(1.) Wrapped and packed into case on the diagonal or pocket-pack system, with wood-wool top and bottom, and the lid nailed down in the usual manner.

(2.) Same as (1) but not wrapped. (3.) Graded from table, handled carefully into cases, and lightly shaken down to settle the fruit, the whole being then conveyed to the central packing-shed and cool store in the same conveyance. The section (3) was then divided, and some wrapped and the others packed plain, as (1) and (2) had been treated in the orchard.

All cases were then placed in the precooler on the same day, and from there passed .to the cool chamber without unnecessary delay. Notes taken on the various comparisons show that (i) and (2) gave excellent results, and were a great improvement on (3), which resulted in a bruised and in many instances skin-punctured condition of the fruit before the further handling required in packing at the' store. The results amply demonstrated that serious damage is done to fruit when the cases are' irregularly filled at the orchard and shaken down in transit to the store, and that such damage may be eliminated almost entirely by packing the fruit in an orderly manner in the case before carting. The ultimate condition of the fruit well repays the extra trouble, not only where it has to be repacked at the store for a special purpose, such as export, but also for local market. Further, it is in a condition for prompt storage, which is a very important factor in the treatment of fruit intended for cool storage, as shown by the report on last season's experiments. The results of this experiment. again demonstrated the important bearing that proper selection, handling, and transit to the store has on the ultimate successful cool storage of fruit. Unless these points are carefully attended to, even an efficient cool chamber cannot give the best results.

I wish to record my appreciation of the valuable assistance and co-operation rendered by the managers of Messrs. Apsey, White, and Co. (Limited), and the Hawke's Bay Fruitgrowers (Limited), which very materially assisted the experiments.