Comparing different methods for evaluating gassing power and fermentation activity of baker's yeast

Providing a quick way to predict the activity of yeast in the baking industry in terms of performance and quality is vital. In this paper, seven instant dry yeast samples of domestic and foreign manufacturers were assessed and compared by four methods for fermentative activity of Saccharomyces cerevisiae: Henry -Simon pressure meter, Gasography, microbial tests and baking test results showed a similar trend for yeast activity and demonstrated further power of Iranian yeast. In gasography and pressure tests, Fariman and French samples produced maximum and minimum gas volumes, respectively. The same trend was seen in microbial test (number of colony forming units) and baking test (loaf volume and height) for these two yeasts. Razavi yeast did not show significant differences with Fariman. Dezmayeh, Golmaye, Kelarmaye, Turkish and France yeasts showed significant differences compared with Razavi and Fariman (P<0.05). All tests showed a close correlation with the baking test. Using the pressure meter as the best method to assess the gassing power of bakery yeast was proposed. This quick and simple test can be a suitable alternative to long cooking methods to observe the capability of CO2 production in bakers’ yeasts.