Yeast Strains from Burukutu and Fura, as an Alternative for Commercial Baker’s Yeast
Abstract
Baker’s yeast has been employed in the manufacturing of bread for at least 6,000 years ago. They are responsible for dough leavening and without them sugar in the dough will not be reduced and the substrate will be left unleavened. They have been identified by Scientists as Saccharomyces cerevisiae and are easily obtainable from fermenting fruits and beverages of high carbohydrate content. This work was carried out to determine the possibility of isolating baker’s yeast from two local drinks, Burukutu and Fura. The drinks were prepared and allowed to ferment for 72hrs and cultured on Sabouraud Dextrose Agar (SDA) plates incorporated with chloramphenicol for 48hrs. Colonies that grow were counted and sub-cultured on Yeast Peptone Dextrose (YPD) Medium for 72hrs. Discrete colonies were sub-cultured, stored, identified and characterized. Their attributes as baker’s yeast such as ethanol and stress tolerance, flocculation, hydrogen sulphide production, temperature tolerance and fermentative ability were determined. Results showed that two isolates were selected and identified as ‘Isolated yeast from burukutu (IYB), Isolated yeast from fura (IYF)’. They showed similar microscopic appearance with reconstituted conventional commercial baker’s yeast (CCY) such as the presence of ellipsoidal to oval cells with multipolar buds and ascospores. The multipolar buds were highest in IYB and lowest in CCY. Yeast count ranges from 3.7X103 to 2.8X103 colony forming unit per millilitre (cfu/ml). All the isolates were able to tolerate different concentrations of ethanol and temperature regimes at varying intensities. None of the isolates produced hydrogen sulphide but show intense to moderate response to stress, flocculation and fermentative ability. Local beverages (Burukutu and Fura) are therefore recommended to be good sources of baker’s yeast which can compare favourably with the conventional commercial baker’s yeast.
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Introduction
Baker’s yeast had been and is still an inevitable component of raw materials used by bakers all over the world. They ferment, leaven or increase the volume of dough mixed for bread and other confectionary products through gas (CO2) incorporation. They do not only increase the volume of the dough through carbohydrate utilization and gas incorporation but also help in creating the desired flavour and texture in the dough (Fleury et al., 2002; Umeh et al., 2019; Sergei, 2020; Casas-Godoy et al., 2021). During fermentation process in the dough, large quantity of CO2 is produced. Baker’s yeast had been identified by researchers as Saccharomyces cerevisiae and is the most commonly used species of Saccharomyces in bread baking. It has been employed as baker’s yeast in manufacturing bread for at least 6,000 years ago (Kevin, 2005; Sergei, 2020; Casas-Godoy et al., 2021).
In Nigeria and some countries, Baker’s yeast is only obtained by importation from Europe or America due to the delicate means of preservation. They are mainly used as dried, preserved as powders and are delicate to handle. Researchers had deduced that Saccharomyces cerevisiae does not inhabit any other environment except nature. They can be isolated from vinery environment as wild or domesticated species (Martin et al., 1993; Mortimer, 2000; Umeh et al., 2019). Kurtzman and Fell (1998) reported that fruits, vegetables, drinks and agricultural products are among the important micro habitats for wild yeasts.
Conclusion
The two local drinks studied showed good sources of baker’s yeasts which competes and is found to be more potent than the conventional baker’s yeast. These isolated yeasts can be potentially employed in baking and confectionary industries to reduce the cost on importation of the conventional baker’s yeasts.