Title : Bioconversion of off-flavor compounds in pea protein isolates using selected microorganisms
Abstract:
The global demand for plant-based food is increasing due to their health benefits and reduced environmental impact compared to animal-based products. Driven by this trend, pulse-derived protein ingredients have become particularly attractive for developing meat and cheese analogues, owing to their high protein content and technological properties. However, pulse protein isolates often present a significant sensory drawback. Undesirable Volatile Organic Compounds (VOCs), mostly belonging to the aldehyde, alcohol, and furan families, such as hexanal, 1-octen-3-ol, and 2-pentyl-furan, act as key off-flavors. These are commonly described as “beany,” “green,” or “earthy” and severely impact the consumer acceptance.
This study investigates a short-duration, minimal-processing approach to mitigate these offflavors via single-strain bioconversion, without the addition of exogenous sugars or salts. Aqueous solutions containing 12% (w/w) pea protein isolate (PPI) were prepared, sterilized, and individually inoculated with lyophilized cultures of six bacterial and four yeast strains. Samples were analyzed for pH, microbiological profile, volatile compounds (via DHS-GCMS), and sensory characteristics.
Most strains significantly reduced hexanal, pentanal, and other off-flavor volatiles within just 6 hours of bioconversion. While the yeasts Kluyveromyces lactis and Saccharomyces cerevisiae generated a diverse array of esters associated with fruity and floral notes, Brevibacterium linens demonstrated high efficiency strictly in degrading off-flavors. Furthermore, sensory analysis revealed that Geotrichum candidum produced highly neutral samples, whereas lactic acid bacteria (LAB), such as Streptococcus thermophilus and Lactococcus lactis, were strongly associated with desirable lactic attributes.
Finally, a Multifactorial Analysis (MFA) correlating GC-MS and sensory data revealed a positive correlation between the yeast strains, ester production, and the 'fruity' sensory attribute. A similar relationship was observed among LAB, 2,3-butanedione (diacetyl) production, and the 'lactic' attribute. Consequently, even though key contributors to the beany flavor, such as 2pentyl-furan and 3,5-octadien-2-one, remained detectable, the bioconversion successfully yielded distinct, pleasant sensory profiles. This demonstrates the efficacy of the applied treatment and highlights the potential to tailor the aromatic profile of PPIs to suit specific endproduct applications. Future work will focus on process optimization and scale-up using these promising candidate strains.
