February, 1910.] 



115 



Edible Products 



In the preparation of Cacao the author 

 distinguishes between two distinct pro- 

 cesses, on the one hand the fermentation 

 of the pulp— the sweet slimy substance in 

 which the beans lie embedded in the 

 fruit— and on the other the changes 

 which go on in the bean itself, and 

 really have nothing to do with ferment- 

 ation or are only indirectly related to 

 this process. 



The purpose of fermentation is mainly 

 to kill the beans without destroying the 

 enzyme. The proof of this is that the 

 most important changes which appear 

 after fermentation, in the form of the 

 brown colouration of the nibs and the 

 reduction of the bitter taste, are also 

 produced without fermentation if the 

 beans are killed under conditions which 

 do not destroy the action of the enzyme, 

 e.g-, by alcohol, by freezing or by 

 grinding the beans to a pulp. 



The production of a brown colour and 

 the reduction of the bitter principle in 

 Cacao are genuinely related processes. 

 The bitter taste depends upon the 

 presence of tannins, and the brown 

 colour has its origin in the oxidation of 

 these tannins. It is easy to prove that 

 an Oxydase plays a part in the ferment- 

 ation of pacao. If the Cacao beans are 

 heated in water to 75° C. and then 

 ground the appearance of the brown 

 colour and the loss of bitterness alike 

 fail, whereas after heating for an hour 

 to 70° C. the change of colour still takes 

 place. The brown colour can still be 

 produced in beans heated to 75° C. if a 

 small quantity of watery extract of 

 fresh Cacao beans is added. For com- 

 parison one may treat another portion 

 of beans with a similar extract which 

 has been previously heated to 80-100° and 

 the change of colour fails to appear. A 

 similar brown colour is produced in a 

 pure solution of tannins by unheated 

 Cacao-bean-extract, the discolouration 

 commencing at the surface. 



On the basis of these observations the 

 following recommendations are made 

 with regard to the practical treatment 

 of Cacao. 



(1.0 In drying the temperature should 

 not be allowed to rise above 60-70°. 



(2.) ( When fermentation is completed 

 the Cacao beans should be passed 

 through a 5-10 per cent, solution of 

 potash before drying. In this way a 

 removal of acid from the Cacao is 

 brought about which then encourages a 

 further action of the enzyme and conse- 

 quently a sweetening of the product. 

 Cacao prepared in this way is also 

 markedly more soluble and capable of 

 suspension. 



PRICKLY PEAR : A PEST OR A 

 FODDER PLANT ? 



By A, J. Ewart, D.SC, PH.D., f.l.s„ 

 Government Botanist and Professor of 

 Botany in the Melbourne University- 



(From the Journal of the Department 

 of Agriculture of Victoria, Vol. VII., 



Part 9, September, 1909.) 

 As a variety of statements are cur- 

 rent in regard to the value of prickly 

 pear, some of which are highly mis- 

 leading, it may, perhaps, be as well to 

 give a short condensed account of the 

 facts definitely known in regard to this 

 plant, and to its nearest allies. 



Firstly, to dispose of one popular 

 myth, namely, that Luther Burbank 

 was the first to develop a spineless form 

 of cactus. The term " prickly pear" 

 includes various species of Opuntia, 

 some of which have been spineless or 

 nearly so for ages, while even the most 

 thorny forms occasionally develop 

 nearly spineless shoots, which when 

 separately propagated may retain the 

 same peculiarity. In a condition of 

 nature, however, these thornless sports 

 either revert to the thorny condition 

 or tend to be eaten out by stock, 

 the thorniest individuals surviving. 

 Under suitable conditions, however, 

 or when protected in some other way, 

 thornless forms may survive, and a few 

 species in certain genera of Cacti, never 

 appear to have developed thorns. 

 Both at the Sydney and Melbourne 

 Botanical Gardens, thornless varieties 

 of the common Opuntia have long been 

 known, so that at the present day it 

 is impossible for any single person to 

 claim the sole credit of developing a 

 spineless Cactus (Opuntia). 



A much more important misstatement 

 is prevalent as to the value of the 

 Cactus as fodder, some having even 

 gone so far as to advise farmers to culti- 

 vate this noxious pest, to provide fodder 

 for stock. Spiny Cacti can only be used 

 as fodder after special treatment to 

 destroy the spines and spinules or to 

 render them soft and harmless. It has 

 been stated that farmers, in the dry 

 southern districts of the United States, 

 burn off the spines with the aid of a 

 torch and so render the plant available 

 as fodder for stock. This may be of 

 some use in times of drought, where 

 farmers have not provided themselves 

 with stored fodder, but except where 

 abundant supplies of cheap labour are 

 available, it would be a very expensive 

 way of permanently feeding stock. 

 Cacti are exceedingly watery, very poor 



