XII. METHODS FOR THE ANALYSIS OF FRUITS AND FRUIT 



PRODUCTS. 



1. Preparation of Sample. Provisional, 

 (a) JUICES, JELLIES, AND SIRUPS. 



Prepare the fresh juices by pressing the well-pulped fruit in a jelly bag 

 and filtering through muslin. In the case of fresh-fruit juices and fresh fruits 

 the determination of total and volatile acids and sugars should be made at once, 

 as fermentation takes place in a very short time. Portions for sucrose and 

 reducing sugar may be weighed and an excess of lead subacetate added. They 

 can then be kept for several days, if desired, without fermentation. All sam- 

 ples must be transferred without delay to glass-stoppered bottles and kept in 

 a cool place. 



In the case of jellies, thoroughly mix to insure uniformity in sampling. 

 Weigh GO grams into a 300 cc flask, dissolve by frequent shaking, make up to 

 the mark with water, and use aliquots for the various determinations. If the 

 jellies contain starch or other insoluble material, thoroughly mix them before 

 taking the aliquots. 



(b) FRESH FRUITS. 



Pulp the whole well-cleaned fruit in a large mortar or by means of a food 

 chopper and mix thoroughly. In the case of stone fruits, remove the pits and 

 termine their proportion in a weighed sample. 



(c) JAMS, MARMALADES, PRESERVES, AND CANNED FRUITS. 



Thoroughly pulp the entire contents of the jar or can, as directed under fresh 

 fruits ; with stone fruits remove the pits and if desired determine their propor- 

 tion in a weighed sample. In the examination of canned fruits it is often 

 sufficient to merely examine the sirups in which the fruits are preserved. 

 In such cases the liquor may be separated and treated as is prescribed for 

 juices. The relative weights of liquor and fruit may be of value in detecting 

 the presence of an excessive amount of water. 



2. Alcohol. Provisional. 



Determine alcohol in 50 grams of the original material according to the 

 method given under "XIII. Wine," page 83. 



3. Total Solids. Provisional, 

 (a) IN JUICES, JELLIES, AND SIRUPS. 



(1) BY DIRECT DETERMINATION. 



Measure 25 cc of a 20 per cent solution (see 1. (a)) of jelly, or weigh ii.~i 

 grams of juice into a large flat-bottomed dish which contains about 4 or 5 



" If a pipette is used it must be graduated so as to deliver a definite volume of a 20 

 per cent sugar solution after draining a definite time. 



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