44
certain additives are being used to compensate for its absence such as xanthan gum,
guar gum, corn starch and eggs. These non-gluten components added in bread basically mimic the gluten network and thus help in improving the nutritional quality of
bread (Mariotti et al. 2009).
4.4.1.1 Baker’s Yeast
Commercially, baker’s yeast is sold as a preparation of dried cells of one or more
strains of fungus Saccharomyces cerevisiae (Ali et al. 2012). Yeast is used as a leavening agent in bread responsible for raising the bread. It is responsible for the fermentation of sugars present in wheat flour resulting in the production of carbon
dioxide and ethanol as main products. The intensity of fermentation depends upon
the form of yeast and the type of sugar present in dough (Hutkins 2006). In the process of bread making, the strains of Saccharomyces cerevisiae are subjected to several environmental and nutritional stresses such as high sucrose concentration, air
drying and freeze-thawing (Attfield 1997). Sweet dough used for bread baking
might contain 30% sucrose which can cause osmotic stress to the yeast, thereby
damaging the cellular mechanism of yeast (Verstrepen et al. 2004). In order to minimize osmotic stress, yeast cells need to be first acclimatized to such higher sucrose
concentration to carry out the fermentation (Tanaka et al. 2006).
There are several alternatives to baker’s yeast as investigated by Jenson in 1998.
One such yeast is Kazachstania exigua, previously known as Saccharomyces exigua,
and the other which can be used is its anamorph Candida holmii. By the virtue of
being highly osmotolerant and resistant to freezing, Torulaspora delbrueckii and its
anamorph Candida colliculosa can also be used in dough fermentation (Gori et al.
2010). During dough fermentation, when the conditions become too inhibitory,
most probably too acidic for S. cerevisiae, the microbial succession is often carried
out using Candida krusei and its teleomorph Issatchenkia orientalis (Gori
et al. 2010).
4.4.1.2 Baking Technology
Baking industry has evolved tremendously over the past 150 years. Earlier this art
of baking was limited to small villages, but it paved its way to large-scale production in high technological industries. Several methods have evolved keeping in view
the increasing demand of high-quality bread in the market (Decock and Cappelle
2005). Bakery goods are different from other products in which they are raised to
produce goods of low density. In bakery goods, yeast is used as a leavening agent.
Bakery goods are raised due to the production of carbon dioxide by fermentation of
sugars. There are basically three methods by which bakery goods are produced
(Mondal and Datta 2007). Straight dough method is the first method which is used
in which mixing of all the ingredients is carried out in a single step. The ingredients
of the dough might differ according to the availability of equipment and choice of
R. Kumari et al.
certain additives are being used to compensate for its absence such as xanthan gum,
guar gum, corn starch and eggs. These non-gluten components added in bread basically mimic the gluten network and thus help in improving the nutritional quality of
bread (Mariotti et al. 2009).
4.4.1.1 Baker’s Yeast
Commercially, baker’s yeast is sold as a preparation of dried cells of one or more
strains of fungus Saccharomyces cerevisiae (Ali et al. 2012). Yeast is used as a leavening agent in bread responsible for raising the bread. It is responsible for the fermentation of sugars present in wheat flour resulting in the production of carbon
dioxide and ethanol as main products. The intensity of fermentation depends upon
the form of yeast and the type of sugar present in dough (Hutkins 2006). In the process of bread making, the strains of Saccharomyces cerevisiae are subjected to several environmental and nutritional stresses such as high sucrose concentration, air
drying and freeze-thawing (Attfield 1997). Sweet dough used for bread baking
might contain 30% sucrose which can cause osmotic stress to the yeast, thereby
damaging the cellular mechanism of yeast (Verstrepen et al. 2004). In order to minimize osmotic stress, yeast cells need to be first acclimatized to such higher sucrose
concentration to carry out the fermentation (Tanaka et al. 2006).
There are several alternatives to baker’s yeast as investigated by Jenson in 1998.
One such yeast is Kazachstania exigua, previously known as Saccharomyces exigua,
and the other which can be used is its anamorph Candida holmii. By the virtue of
being highly osmotolerant and resistant to freezing, Torulaspora delbrueckii and its
anamorph Candida colliculosa can also be used in dough fermentation (Gori et al.
2010). During dough fermentation, when the conditions become too inhibitory,
most probably too acidic for S. cerevisiae, the microbial succession is often carried
out using Candida krusei and its teleomorph Issatchenkia orientalis (Gori
et al. 2010).
4.4.1.2 Baking Technology
Baking industry has evolved tremendously over the past 150 years. Earlier this art
of baking was limited to small villages, but it paved its way to large-scale production in high technological industries. Several methods have evolved keeping in view
the increasing demand of high-quality bread in the market (Decock and Cappelle
2005). Bakery goods are different from other products in which they are raised to
produce goods of low density. In bakery goods, yeast is used as a leavening agent.
Bakery goods are raised due to the production of carbon dioxide by fermentation of
sugars. There are basically three methods by which bakery goods are produced
(Mondal and Datta 2007). Straight dough method is the first method which is used
in which mixing of all the ingredients is carried out in a single step. The ingredients
of the dough might differ according to the availability of equipment and choice of
R. Kumari et al.