Edible Products. 



214 



[March, 1912. 



ing the crop ready to harvest in July or 

 in the beginning of August, when one or 

 two frosts have touched the plants, the 

 manufacture should be at once begun 

 and carried on until the end of October. 

 If the work is protracted into the spring 

 months, the bulbs begin to shoot, and 

 the yield of starch is consequently les- 

 sened in quantity and deficient in 

 quality. 



Harvesting. 



When the bulbs have come to maturity 

 — that is, in from eight to nine months 

 after planting— and when the plants 

 have, as stated above, had a touch of 

 frost, then is the time to commence the 

 harvest. Mr. D. Lahey, in a paper entitled 

 "When to harvest Arrowroot," said :— 



"A good test for ascertaining when 

 arrowroot is ready for digging is the 

 following :— Observe the outer leaf of 

 the bulb. A triangular slit will be 

 noticed pointing downwards. If the slit 

 appears white, the bulb is still immat- 

 ure, but as soon as it turns purple the 

 crop may be harvested. Arrowroot may 

 be left to stand over for two seasons, as 

 in the case of sugar-cane." 



The latter statement is important, for 

 it has happened in some cases that, when 

 the crop was larger than the available 

 mill power was capable of dealing with, 

 the groweis turned their cattle into the 

 field. Had the crop been held over, it 

 might have been possible to get it in 

 during the next season, and thus avoid 

 a great deal of extra labour. 



When harvesting, the stalks are first 

 cut down with a hoe, cane knife, or reap- 

 ing hook. The stool is then dug up with 

 a strong mattock or a stout-eyed No. 3 

 grubbing hoe. A spade or fork is quite 

 useless for the work, as the stool has a 

 strong hold of the ground, in addition 

 to which the bulbs of Canna edulis 

 cling firmly together by the masses of 

 the rootlets proceeding from each bulb. 

 When free from the soil, the bulbs must 

 be separated, and all earth adhering to 

 them knocked off. As soon as dug, they 

 must be carted to the mill ; therefore, it 

 is well not to take up more than can be 

 operated on each day. Every day's ex- 

 posure to the weather or to the hot sun 

 has an injurious effect upon the colour 

 of the manufactured starch. 



The average return of a good crop is 

 about 30 cwt. of starch, or five to six 

 times the quantity in tons of bulbs. 

 Brom 12 to 20 tons per acre have been 

 dug from a field in which the plants 

 were set at distances of 5 ft. between the 

 plants in rows 6 ft. apart. It goes with- 

 out saying that the yield will vary ac- 

 cording to soil* locality, season, good or 



bad cultivation, and proper washing, 

 grinding, and drying appliances ; but, 

 as a general rule, the yield of starch may 

 be set down at from 15 cwt. to 30 cwt. per 

 acre, although under most exceptional 

 circumstances, it is recorded that as much 

 as 4 tons of finished arrowroot per acre 

 have been obtained. I cannot, however, 

 vouch for this statment. 



Machinery and Manufacture. 



The machinery employed in the manu- 

 facture of arrowroot in the very early 

 days of agriculture in Queensland was 

 as primitive as that used by the ancient 

 Britons for pounding grain or by the 

 Australian natives for crushing the 

 seeds of nardoo. The first growers made 

 use of a grater made by punching holes 

 with a nail in a piece of kerosene tin. 

 Gradually improvement crept in, until 

 a hand machine was constructed by the 

 writer which much accelerated the 

 work, but was still only a makeshift. 



Since that time modern machinery has 

 been introduced capable of turning out 

 from 10 cwt. to 30 cwt. of commercial 

 arrowroot per day. Such a plant may 

 be thus described : — 



Motive power, a 6 to 10 h.p. engine, 

 root washers, carriers, grinding mills, 

 cylinders, elevators, rotary sieves, 

 shaker sieves (two), chute patent 

 circuitous trough (for which Mr. Lahey 

 holds a patent), agitators and sieves, 

 centrifugals for draining, tables, and 

 calico for draining. 



The whole of the work, after the 

 tubers have been raised to the highest 

 point of the building, is effected by 

 by gravitation. The tubers (or roots as 

 they are erroneously called), as they 

 come from the field, are tipped from the 

 drays on to the carrier, whence they are 

 automatically carried to the tuber- 

 washing trough. Running through the 

 centre of this is a spindle with diagonal- 

 ly inserted pegs of sufficient length to 

 clear the bottom and sides of the trough 

 by about 1 in. Here the bulbs are 

 thoroughly cleaned of all dirt, stones, 

 &c, and they are then passed on to the 

 grater, which is a large, wooden 

 cylinder covered with perforated iron 

 burred, on to which the bulbs drop from 

 a hopper. A stream of water pours 

 upon this continuously from above, and 

 the pulp and starch held in suspension 

 pass on to a shaking sieve. From this the 

 farina and water pass to a second sieve, 

 the pulp being ejected on the other side 

 of the first sieve. On leaving this sieve, 

 which is perforated with very fineholes, 

 the water and farina are shot into a 

 large trough, where the latter soon 

 settles at the bottom, 



