Abstract
Apparatus for testing strength is reviewed, attention being drawn to the different physical principles involved. The American definition of pectin jelly grade has been adapted to conform with English jam‐manufacturing practice, and the effect of different conditions of gel preparation is described. Rate of cooling and Ph are more important factors than type or quantity of buffer, and temperature of ageing and soluble‐solids content both exert considerable influence above Ph 3.0. Points are listed for consideration when formulating a laboratory procedure for jelly sideration when formulating a laboratory procedure for jelly grading. Methods of determining the rate of set are briefly described.

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