258 Chemical Tests and Analyses 



Chapter XXX. 



PRACTICAL METHODS OF SYSTEMATIC EXAMINATION 

 OF PRODUCT FOR MARKETABLE PROPERTIES 



The manufacturer should know at all times the quality and 

 keeping quality of his product. He should have a systematic check, 

 not only on his product stored in the factory, but also on the goods 

 in transit and on the market, in order to promptly detect goods that 

 show signs of deterioration. This will enable him to investigate the 

 cause of the defect, to prevent its recurrence and to avoid spoiled 

 goods from reaching the consumer. The following simple method 

 of systematic examination has been found effective in keeping a re- 

 liable check on each batch until the product is old enough to have 

 proved its immunity from the usual specific defects. 



Number of Samples Needed. — B'ive cans of every batch of 

 condensed milk or evaporated milk, bearing the corresponding batch 

 number, are reserved for this purpose. For convenience's sake these 

 sample cans are best stored on shelves about fifteen inches wide and 

 five inches apart. These dimensions are sufficient to conveniently 

 accommodate five 16-ounce cans of one and the same batch and 

 placed in a row, one behind the other. These shelves should be in- 

 stalled in a place, preferably the office, where the cans may be ex- 

 posed to similar changes and extremes of temperature, as is the case 

 in transit and in the retail store. The cans of sweetened condensed 

 milk should be placed on these shelves bottom-side up. The cans 

 of evaporated milk should be placed on the shelves right-side up. 



Frequency of Examination. — Every day one can of condensed 

 milk or other product, one, three, ten, thirty and sixty days old, re- 

 spectively, is opened and the contents are carefully examined for 

 thickness, smoothness, sugar sediment, curdiness, fat separation, 

 color, flavor, fermentation changes, etc. 



Technique of Examination. — Since the temperature of the 

 product influences its apparent thickness, it is desirable to examine 

 the condensed milk at a uniform temperature, preferably 60 or 70 

 degrees F. This is best accomplished by the use of a water-tight 

 tray of galvanized iron or tin, about twelve inches long, nine inches 

 wide and three and one-half inches deep, with an overflow about 



