NEW ZEALAND APPLES

Otago Daily Times, Issue 22066, 23 September 1933, Page 15

NEW ZEALAND APPLES

STORAGE IN ABNORMAL ' " ' ATMOSPHERES ■RECENT RESEARCH. (From Our Own Correspondent.) LONDON, August 5. A section of the report of. Food Investigation Board (H.M. Stationery Office, ss) is devoted to experiments with New Zealand apples. Information has been sought at the Cambridge Low Temperature Station as to the ■ best temperatures at which to hold New Zealand apples in storage after overseas transport, and inquiries have also been made as to whether the employment of gas storage for such fruit would be an advantage. Two cases of each ,of the following varieties were received from the New Zealand Fruit Board 15 days after unloading, the interval having been spent in cold storage: Delicious, Rome Beauty, Dougherty, Ballarat, Rokcwood, Granny Smith, Statesman, Stunner, and Tasma. Two artificial atmospheres, says the report, obtained by restricted ventilation, and. containing respectively 5 per cent, carbon dioxide + 10 per cent, oxygen and 10 per cent, carbon dioxide -f 11 per cent, oxygen were used, in each case botlr at one degree C. (3 4 degrees Fahr.) and at three degrees C. (37.5 degrees Fahr.). Comparable samples of fruit were also stored in air at one degree, three degrees, and 15 degrees C. (59 degrees Fahr.). The fruit in air at 15 degrees C. (59 degrees Fahr) showed 15 per cent, wastage after three weeks, 40 per cent, after live weeks, and 100 per cent, after two months. This wastage was mainly duo to fungal rotting. There was little obvious difference after two months as regards the fruit, between one degree and three degrees C., or between either of the two atmospheres tested and air. On an average about 10 per cent, wastage occurred, and the general conditions of the fruit was surprisingly good. The wastage was mainly breakdown and not fungal rotting. From a commercial point of view no special significance should be attached to the actual amount of wastage, because the samples were small and had received much extra handling.

Wrapping Granny Smith, apples in oiled wrappers prevented scald and superficial blemish. After two months wrapped fruit was practically free from superficial blemish, while unwrapped fruit, though still green, was so badly blemished as to be worthless. CARBON DIOXIDE.

The most striking outcome of this experiment is that two months’ exposure to 10 per cent, carbon dioxide at 34 degrees Fahr. had no injurious effect whatever on any of the nine varieties tested. Experiments with English apples indicated that some damage with 10 per cent, carbon dioxide at temperatures as low as 34 degrees Fahr. was to be expected. But it must be borne in mind that, whereas the English apples were gas stored immediately, or soon after gathering, the New Zealand apples were well advanced in their storage life (two to three months in cold storage during transport and afterwards) before they were transferred to gas storage. These results stress the need for more knowledge about the relation in apples between age and tolerance of abnormal atmospheres. It seems possible that the apple is far more sensitive to injury at its climacteric stage, which usually occurs soon after gathering. The history of the last Australian season showed that injury on board ship from abnormal atmospheres is still a by no means completely solved problem. The absence of arty apparent benefit from gas-storage within the duration of the experiment is not altogether surprising in view of the fact that the fruit, when received, had already passed through half its storage life. Differences would probably have shown themselves if the fruit could have been stored longer and the wastage developing after removal from gas-storage at intervals accurately followed. Further experiments are advisable to test atmospheres containing low amounts of both oxygen and carbon dioxide, as, for example, 5 per cent, oxygen plus 5 per cent carbon dioxide. Such mixtures cannot, of course, _ be obtained by simple restricted ventilation, but a method has now been worked out for obtaining them. STORAGE BELOW FREEZING' POINT.

Three weeks after their arrival at the laboratory, during which time they had been stored in. their cases at sdeg. O(4 Id eg. F.) all the varieties were in excellent condition. Samples of Delicious, Rome Beauty, Dougherty, Ballarat and Rokcwood were then stored at Odcg., Idcg., 2deg., 3deg., and sdeg. (i.e., 32deg. ; 30.2 deg.,. 28.4 deg., 20.0 deg., and 23deg. F.). The samples were examined after 18, and again after 70 days, and in each case the behaviour of the fruit during several weeks after removal from the freezing temperatures was noted. There was a striking contrast between the effects of sdeg. C. (23deg. F.) on the one hand, and of 3deg. C. (26.0 deg. F.) and higher temperatures on the other. At sdeg. C. all the fruit of .each variety-' was badly damaged by even a short exposure, and collapsed completely on thawing. At 3deg. C. and higher tcinpcralures there was,little visible sign of freezing, and. the fruit did not collapse after removal to higher temperatures. At 3cieg. C. a few specimens of each variety showed, when cut open immediately after removal from the low temperature, a slight mottling or streaking with injected areas. In the case of tile Ballarat,variety this featiue was observed also at 2deg. C. A few specimens also, of Rome Beauty and Ballarat at 3deg. C. showed’ the hue wrinkling of the skin -which indicates the presence of ice. A thorough examination of the internal condition of the fruit was made immediately after the final removal (after 70 days) from freezing temperatures, and again 5 days later. None of the fruit fiom 3cleg. C. and higher temperatures showed, on "either occasion, any of the effects usually associated with injury by freezing. The wastage was entirely of the type described as low-temperature internal breakdown.