Abstract
An investigation was made for clarifying the qualitative characteristics and the usage for actual cooking of the commercial gelatins by comparing with the alkaline processed gelatin extracted in the low temperature (60°C) as the control. The results can be summarized as follows.
The qualities of gelatin can not be judged from the appearance of xerogel, but by the transparency and color of sol. The commercial gelatins have been classified into the alkaline processed gelatin and the acid processed gelatin, and the production of alkaline processed gelatin was larger than the acid ones. On swelling gelatins it is desirable to add more than twice weight of water as much as gelatin and to keep more than 15 min. Even if the indications say that the gelatin is able to dissolve in hot or tepid water, it is advisable to swell with water as the normal gelatin. In the case of the commercial gelatin sol containing sugar, the temperature range between the starting point of increasing the viscosity and the gelation point was wide. This was due to the wide distribution of the molecular weight. In the case of alkaline processed gelatin, the higher molecular weight gelatin had the higher rupture stress. However the molecular weight of acid processed gelatin was much lower than alkaline processed one even though having the same rupture stress. The results for the measured rupture characteristics were confirmed by the sensory test.
