COLOURING CITRUS FRUITS

Sun (Auckland), Volume II, Issue 388, 23 June 1928, Page 27

COLOURING CITRUS FRUITS

INTERESTING TRIALS ARTIFICIAL METHODS USED Experiments that are likely to have an important influence on the sales of citrus fruits in Australia have recently been successfully conducted. With the steady development of the citrus industry experience has shown that the public demands well coloured fruits. A colour standard is also insisted on in regulations controlling the sale of fruit. Unfortunately much of the fruit that has been consigned to market in recent seasons has possessed a good deal of colour, but frequently it has lacked sugar content. This class of produce has had a detrimental effect on subsequent sales, for consumers, finding it sour and uninviting to the palate, have refrained from purchasing further supplies until long after oranges have attained the desired sweetness. This has naturally curtailed distribution. It is characteristic of Queensland-grown oranges that while the juices develop their sugars fairly early in the season the rind is slow in colouring, and often while the exterior is quite green the pulp is sweet and acceptable for dessert purposes. Thus the desire to obtain well-coloured fruit has operated against the ready sale of the more fully developed produce. This season it is likely that larger quantities of Queensland fruit than usual will be placed on the Melbourne markets for the reason that the Citrus Growers’ Association in that State has affiliated with the Victorian Central Citrus Association. Mr. W. S. Fong, of the firm of Tim Young and Co., of the Western Market, realising that the green appearance of this fruit may be prejudicial to its sale, decided to experiment with the ethylene gas treatment, a process which is largely used in California to “even” the colour of a pack. As a trial a small chamber was fitted so that the gas from the cylinders could be admitted in varying quantities, and provision was made for raising the temperature to the requisite heat. A gauge regulates the supply of ethylene gas, which is admitted to the chamber in the proportion of a foot of gas to each 1,000 cubic feet capacity. The fruit which is stored in the ordinary packages is placed in the compartment, to which the gas is admitted, and is retained there for a period of approximately 84 hours, during which a steady temperature of 70 degrees Fahr. is maintained. For the purposes of the experiment between 40 and 50 cases of Queensland oranges, which were so green in appearance as to render them unsaleable, were placed in the chamber, with several cases of similar fruit from New South Wales, and a number of cases of lemons. When these were removed very little trace of green was noticeable, that colour being chiefly in evidence on some lemons, which were not sufficiently advanced in growth at the time of storage. All the oranges were evenly coloured and attractive in appearance, while the majority of the lemons were of a natural brightness that suggested that they had been ripened in ordinary conditions. Apart from the value of the experiment as it affects the Queensland-grown early oranges, the results are of considerable importance, for in times of scarcity it will enable fully coloured lemons to be made available almost immediately.