220 THE PRESERVATION OF MEAT, ETC. 



tenaciously retains the dust and accompanying germs that are 

 blown on to it. Thus, M. T. SCHNIRBR (I.) discovered virulent 

 tubercle bacilli on the surface of grapes sold in the Vienna 

 market. 



A word must be added with regard to the gelatinisation of 

 fruit-juice. As is well known, the cells of many fruits are rich 

 in pectin, which, when the cells are crushed, passes into the juice 

 and causes it to coagulate. This phenomenon was explained by 

 Fremy, in 1840, to be due to the action of an enzyme, viz., pectase, 

 whereby the pectin is converted into pectic acid. This opinion 

 was modified by the researches of G. BERTRAND and A. MALLEVRE 

 (I.), in so far that they showed that the enzyme can accomplish 

 the transformation referred to only when in presence of soluble 

 salts of the alkaline earths (e.g. lime), with which the pectic 

 acid enters into combination, and forms insoluble pectates. The 

 presence of this gelatinising compound is indispensable for the 

 preparation of pure fruit jellies; and the latter must not be too 

 strongly boiled, or their setting properties will be diminished or 

 completely destroyed. In the preparation of fruit juices, such 

 as raspberry juice, it is necessary, on the other hand, to get rid of 

 these pectin substances, because they detract from the utility of 

 the juice, which should remain liquid. This end is attained by 

 leaving the fresh juice to itself for a time, fermentation soon 

 ensuing, by which the pectin or pectate is decomposed. The juice 

 is then strained and boiled down after the addition of sugar. A 

 few references to the literature of the subject will be useful to 

 the food-stuff chemist, who is not infrequently asked for advice 

 concerning the best means of turning fruit to account. Full 

 particulars on the treatment of fruit in general, as also of drying 

 and preserving it, will be found in the handbooks of FR. LUCAS 

 (I.), KARL BACH (L), and H. TIJIM (I.). A brief introduction to 

 the preparation and treatment of fruit wines has been arranged by 

 M. BARTH (I), and a pamphlet written by W. TENSI (I.) deals 

 chiefly with currant-wine (as the finest of all fruit wines), as 

 well as with gooseberry wine, &c. 



The preservation of wine-must is practised on a large scale, 

 particularly in Sicily. To render the juice highly suitable for 

 transport, it is (after a preliminary filtration) concentrated in 

 vacuo at 40 C. to about one-fourth of its original volume. In 

 this manner a thick, syrupy mass is obtained, the composition 

 of which can be deduced from the following analytical figures 

 furnished by TH. OMEIS : 



Water 35.1 per cent. 



Dextrose + levulose .... 62.2 ,, 



Acid 1.2 ,, 



Ash 0.7 ,, 



Albumin, gum, &c 0.8 ,, 



