The Impact of Different Fermentations on the Antifungal Activity of Sourdough Bread

  • Author / Creator
    Bumanis, Zoe
  • Bread is considered a staple food in North America and Europe, but due to its neutral pH and high water activity it is vulnerable to spoilage by Penicillium spp., a problem that costs the commercial baking industry millions each year and contributes significantly to global food waste. Common methods of chemical preservation like calcium propionate (CalPro) and sorbic acid are falling out of favour with ingredient-conscious consumers, leaving a hole in the market for a bread with few or reduced preservatives. Sourdough, a mixture of water and flour fermented by lactobacilli and yeasts, is often used in bread production to improve flavour, texture, and to contribute to leavening. It has also displayed preservative effects against mould which increase the shelf life of the product.
    The antifungal impact of 12 strains of lactobacilli incorporated into 10% sourdough breads were compared to one another and revealed to result in equivalent shelf life when inoculated with the highly-resistant spoilage organism Penicillium roqueforti. However, altering the time and temperature combinations used in fermentation and proofing protocols resulted in an increase in shelf life which matched that of bread containing 0.3% calcium propionate, even in a 'worst-case' exposure scenario. It was also determined that a combination of 0.1% calcium propionate and sourdough was similarly effective in delaying fungal spoilage. The inclusion of buckwheat in the fermentations and the subsequent impact on shelf life was recorded for the first time, and the benefits of isomerized ɑ-acids sourced from hops were supported by the findings of this study, which identified both additives as effective ways to extend the mould-free shelf life of sourdough bread past what is possible using only wheat flour.
    This research posits that a three-pronged approach utilising the products of sourdough fermentation, antifungal adjuncts, and a clean processing area can not only reduce instances of fungal contamination but also lead to improved resistance and extended shelf life when contamination does occur in preservative-free or reduced-preservative bread, providing a benefit that cannot be achieved by any one of these factors alone.

  • Subjects / Keywords
  • Graduation date
    Spring 2024
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.