Making Food From Fruit Stones

Press, Volume CIV, Issue 30739, 1 May 1965, Page 5

Making Food From Fruit Stones

(■Contributed by the D.5.1.R.) TOURING recent research work at the D.S.I.R. Chemistry Division at Gracefield on the properties of almond and stonefruit kernel oils, the possibility of using apricot kernels from canning and jam manufacture for the production of useful products has become apparent.

This work has led to the suggestion that some such products could probably be economically produced in New Zealand, using materials that at present -are discarded as waste. One fortunate circumstance is the concentration of apricot growing and processing in one region. Almost all of New Zealand’s commercial apricot orchards are confined to Central Otago and because of this, processing of apricots is restricted mainly to Dunedin and Roxburgh. This means that all available stones could be readily collected in one central plant, with consequent low freight costs.

Apricots are closely related to almonds, and apricot kernels are very similar in composition to almond kernels. Apricot kernels can therefore be used to make products normally prepared from almonds, such as nut-meal and marzipan—which are high-priced products—as well as ingredi-

ents for biscuits, cakes and other bakery and confectionery products. An alternative use for apricot kernels is the production of oil. They contain a high percentage of oil that is almost identical in properties to almond oil, and which can be used in cosmetics and pharmaceuticals. It also makes an excellent table oil. High In Protein The “cake” left after the oil has been squeezed from it is high in protein, and can be made into a quality stock or poultry food that should find a ready market here. Another product, an almond-type flour, could also be produced for use in confectionary and cosemetics. In California, even the broken apricot shells are used for producing a highgrade charcoal that is briquetted and sold as barbecue fuel. Although this may not be warranted in New Zealand, the shells should make a useful steam-raising fuel in a processing factory. In this way, the entire kernel could be used beneficially. Almond Imports New Zealand imports approximately 20 tons of ground almonds every year, so that a local market should be available for all the apricot kernel meat that could be produced. The most profitable local use would be to produce nutmeal and marzipan substitute, but an alternative is

the production of oil. Approximately 35 per cent of oil can be extracted from apricot kernels. This oil is almost identical to almond oil and can therefore be used for the same purposes. The production of apricot kernel oil is relatively simple, but New Zealand’s use of almond oil is only about 10 cwt each year, so that the bulk of oil produced here would have to be exported. Apricot kernels have been processed for many years in both Europe and the United States for the production of oil, kernel-meal and marzipan. Kernels are an item of international trade and are exported to processors in Europe from many sources, including China, South Africa and Australia. Jam Residue In New Zealand kernels have not, in the past, been recovered during processing of fruit. The scale of local industry has not warranted it, but processing has now grown to the stage where the recovery and use of kernels should be feasible. In the 1962-63 season, approximately 1306 tons of apricots was canned or made into jam. Work carried out in the laboratory on the proportions of dry kernel to fruit showed that this varied from about 1 per cent to 1.5 per cent, according to the size of the fruit—the smaller apricots used in jam manufacture have the high ratio—and about

13 tons of kernels could, therefore, be recovered. These could, of course, be exported as such. Prices on the international market over the last few years have ranged from 230 s to 380 s a cwt which, for 13 tons, would represent £3OOO to £5OOO. Plant Available It seems preferable, however, that the kernels be processed locally, as the value of nut-meal and marzipan that could be made from them would be considerably greater than this. Simple machinery is available for the extraction of apricot kernels from their stones. The stones are crushed between heavy iron rollers, which are adjusted so that the kernels are not broken. The broken shells and whole kernels drop from the crusher into a tank of brine, in which the kernels float, and the pieces of shell kink. The kernels are then skimmed from the surface, washed, and mechanically cleaned to remove shrivelled kernels and extraneous matter. “Debittering” Amygdalin, the bitter ingredient in bitter almonds, is also present in apricot kernels, and they must therefor be “debittered” before use. Kernels are first blanched by soaking in warm water to soften and loosen the skins, following which they are mechanically peeled. The peeled kernels are again soak-

ed in water for an hour, after which they are chemically treated. Two basic products can then be made: Kernels with a strong “almond” flavour, and "sweet” kernels, from which the essential oil has been removed by steam distillation. This essential oil, bitter oil of apricot, is almost identical to Oil of bitter almonds, and can be used in the manufacture of almond essence for flavouring and in medicine. Marzipan The two types of debittered kernels thus produced are then ground, and can be mixed to give blends of nut meal with varying degrees of “almond” flavour or mixed with sugar to make marzipan. Apricot kernel oil can be produced quite simply by grinding the kernels, followed by a slow pressing process in a perforated cage press. The resultant product is a good quality oil that requires little treatment to produce a bland, light-coloured oil. The laboratory considers that production of apricot kernel oil could follow the manufacture of other apricot kernel products. It might then be possible to press other stone-fruit kernels, especially plums, to further the advantages of making food from waste.

If you want to be a collector you must first make yourself an expert on forgeries.— Sir Chester Beatty.