Microbiology Research Journal International

Background: The baking industry is a significant contributor to the global food sector, with the global bread and bakery market projected to reach USD 573.2 billion by 2028, driven by increasing population and changing consumer preferences. However, the industry faces challenges in sustainability, particularly in reducing food waste, with approximately one-third of food produced globally being wasted, highlighting the need for innovative solutions like sourcing alternative yeast strains from spoiled fruits.

Aim: This study aims to source alternative baker’s yeasts from deteriorated fruits.

Study Design: The study employs statistical analysis of the data interpretation.

Methodology: Deteriorated fruits (cucumber, watermelon, banana, pawpaw, orange, and pineapple) were collected from local fruit vendors in Rumuokoro market, located in the Obio/Akpor Local Government Area of Rivers State, Nigeria. These fruits were selected due to their common occurrence in markets and their high likelihood of spoilage, which may harbour diverse yeast populations. The collection process will involve visiting multiple vendors to ensure a variety of samples. Each fruit was properly labelled and transported to Laboratory within 24 hours after purchase and was subjected to microbiological procedures, which included standard plate counts, biochemical, morphological and microscopic identification of the isolates.

Results: Yeast counts varied significantly among the fruit samples, with pineapple recording the highest yeast population (7.64 ± 0.14 log₁₀ CFU/g) and banana the lowest (5.00 ± 0.00 log₁₀ CFU/g) (p = 0.00015). A total of thirty-six (36) isolates belonging to the following genera Pichia, Candida, Debaromycces, Meyerozyma and Saccharomyces. The isolates were screened for sugar fermentation, pathogenicity and tolerance tests, resulting in selecting seventeen (17) isolates. After the subjection of the seventeen (17) yeast isolates to leavening activity, dough rising capacity (DRC) and baking trials, the number of yeast isolates was reduced to two (2) genera, Pichia and Saccharomyces. The data obtained were analysed statistically using SPSS version 24. Results indicated that Pichia and Saccharomyces species exhibited leavening activity and dough rising capacity comparable to the control (commercial yeast), suggestive of evolution of carbon (iv) oxide significant for enhanced bread quality.

Conclusion: This study identified wild yeast isolates from agro-waste fruits, particularly Pichia kudriavzevii and Saccharomyces cerevisiae, with fermentative efficiency comparable to commercial baker’s yeast. These strains offer a sustainable, cost-effective alternative for bread production, reducing reliance on imported yeast while maintaining quality. Further optimisation could enhance their industrial application. Future research should focus on molecular characterisation, fermentation optimisation, large-scale trials, expanded applications, sensory evaluation, and industry collaboration to fully harness these yeast isolates potential.