Comparative Efficacy of Different Brands of Baker’s Yeast Used in Bread Production in Jos Metropolis, Nigeria

Consumption of bread and other baked aerated wheat flour products has spurred the needs to determine the leavening ability of different brands of baker’s yeast used in bread production. In this study we assessed the leaving ability of different brands of baker’s yeast in production of quality bread and the flour used in baking test was Dangote flour. Seven brands of different commercial baker’s yeast were collected from the 13 different brands sold in Jos market. These brands includes: Angel instant active dry yeast (ANGY), Saf-instant active dry yeast (SAFY), Food mont instant active dry yeast (FOMY), Pasha instant active dry yeast (PASY), STK- Royal active dry yeast (ROYA), Vahine active dry yeast (VAHY) and Fermipan active dry yeast (FEMY). The results of the viability tests for the different brands of active dry yeast indicated that six out of the seven brands were 100% viable while one had only one dead cell. Statistical analysis (one-sample-t- test) revealed that there was significant different among the different brands of yeasts used (p<0.05), however ANGY had the highest performance viability (p<0.002) and PASY had the least (p<0.039) as shown in Table 3 in appendix. The result of the pH variation as function of time at 260C shows steady decrease in pH values of all the different brands of yeast suspension. Using regression analysis, pH at 150 minutes contribute 96 percent to the leavening ability of different brands of baker’s yeast used in bread production and 30 minutes contribute the lowest 9.1 percent as shown in the Table 4 in the appendix. It was concluded that all the seven brands of baker’s yeast tested were suitable for use in bread production when compared with the standard.

Optimization of the cultivation conditions of indigenous wild yeasts and evaluation of their leavening capacity

Ethiopia has a high demand for baker’s yeast in the bread and beverage industries. Unfortunately, Ethiopia has no producing plant for baker’s yeast and instead relies on costly imports. The objective of this work was to identify the most productive and useful indigenous baker’s yeasts isolated from local fermented foods and drinks, honey and Molasses using leavening ability as the major metric. Six of the test isolates produced a maximum cell mass at 30°C, pH of 5.5 and 48 hours of incubation. Isolate AAUTf1 did not produce hydrogen sulfide, while isolates AAUTf5, AAUTj15 and AAUSh17 produced low levels of this chemical, and isolates AAUMl20 and AAUWt21 produced high levels of hydrogen sulfide, neglecting their utility in baking. The leavening performance of isolates AAUTf1 (Candida humilis) and AAUTf5 (Kazachstania bulderi) had the highest dough volume of 131 cm3and 128 cm3respectively in 120 min. Isolates AAUSh17 (Saccharomyces cerevisiae) and AAUTj15 (Saccharomyces cerevisiae) raised the dough volume of 127 cm3and 125 cm3respectively, at 60 min compared to commercial yeast (117 cm3in 90 min). The study also revealed that mixed cultures of indigenous yeasts had better leavening capacity than single cultures. The co-inoculated cultures of AAUTf1 + AAUTf5 + AAUTj15, AAUTf5 + AAUTj15, and AAUTf1 + AAUTj15 + AAUSh17 reached 143 cm3at 90 min, 141 cm3and 140 cm3both at 60 min, respectively. Thus, the indigenous isolates are candidates for optimizing utilization of yeast for fast promotion and utilization in the bakery industries.

Comparison of Leavening Ability of Kluyveromyces lactis in Different Bread Dough Formulations

The aim of this study was to evaluate the dough proofing activity of Kluyveromyces lactis (ATCC 8585) in different dough formulations and to compare it with the commercial active dry bakery yeast Saccharomyces cerevisiae. Leaving ability of yeasts was tested in lean and rich dough. For both cultures, lean and rich dough mixtures containing 0.3 g of yeast biomass (on dry weight basis) and wheat flour in 15 ml of water was prepared. Rich dough contained also either 2.0 g of sucrose, 2.0 g of lactose or 2.5 g of whey powder. Dough mixtures were incubated at 29°C and volume increase was recorded every 15 min. We determined that Kluyveromyces lactis had higher volume and leavening rates compared to commercial bakery yeast strain in lactose-rich or whey-rich dough. These results demonstrated the potential of Kluyveromyces lactis yeast strain as a suitable culture for whey fortified bread making.

Selection and Characterization of Potential Baker’s Yeast from Indigenous Resources of Nepal

The study aims to isolate the yeast strains that could be used effectively as baker’s yeast and compare them with the commercial baker’s yeast available in the market of Nepal. A total of 10 samples including locally available sources like fruits, Murcha, and a local tree “Dar” were collected from different localities of Bhaktapur, Kavre, and Syangja districts of Nepal, respectively. Following enrichment and fermentation of the samples, 26 yeast strains were isolated using selective medium Wallerstein Laboratory Nutrient Agar. From the differential tests which included morphological and microscopic observation and physiological and biochemical characterization such as nitrate reduction and lactose utilization tests, 8 strains were selected as possible Saccharomyces strain. The selected strains were further assessed for their efficient leavening ability by tests such as ethanol tolerance, osmotolerance, invertase test, and stress exclusion test. The three most potent strains ENG, MUR3B, and SUG1 isolated from grape, Murcha, and sugarcane, respectively, were used in the fermentation and baking of dough. These strains also carried a possibility of being used as industrial baker’s yeast.