A Proposal of a New Method on the Quantitative Test for Gas of Baking Powders

Abstract

In order to establish a rapid and accurate method for the quantitative test for gas of baking powders, this research was undertaken. Three methods were subjected to comparison; i. e. contemporary official method of Japan (volumetric method) in which the gas produced in hot water was measured directly, an improved volumetric method proposed by the authors and absorption-titration method used in the alkali manufacture.
In the improved volumetric method a trial manufacture prepared after the performance of several improvements on Chittick's apparatus shown in the Official Methods of Analysis of AOAC was used. The volume of gas produced at 75°C under the addition of hydrochloric acid was expressed at the normal state.
The principle of the absorption-titration method is as follows: The method consists of boiling sample with acid in an evolution flask, expelling the evolved carbon dioxide completely into the absorption apparatus containing solution of sodium hydroxide and barium chloride and, after shaking the apparatus vigorously, back titration of the residual hydroxide was carried out with standard acid solution under the atmosphere free from carbon dioxide., AGK-type apparatus was used.
Satisfactory results were obtained on sodium bicarbonate standard by use of the modified volumetric method and absorption-titration method, the recoveries of carbon dioxide being around 100% and coefficients of variation being within 3%. Contrary to this, it was impossible to produce gas from sodium bicarbonate by the contemporary official method. The addition of alum, calcium phosphate or tartaric acid allowed the production of gas, the gas volume measured, however, varied from one to another.
From the comparative experiments of single-type baking powders (three commercial products were used) it was confirmed that no significant differences were observed between the values obtained by both improved volumetric method and absorption-titration method, the reproducibilities being satisfactory. The contemporary official method was apt to give too low gas volumes.
The adoption of the modified volumetric method seems to be advantageous since the time necessary for measurement of one sample (including blank test) is only 15 minutes, a quarter compared with the absorption-titration method. In Japan the gas evolved from 2g of baking powder must not be less than 70ml.