AUTHOR=Perpetuini Giorgia , Rossetti Alessio Pio , Rapagnetta Arianna , Tofalo Rosanna 

TITLE=Unlocking the potential of Kluyveromyces marxianus in the definition of aroma composition of cheeses

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1464953

DOI=10.3389/fmicb.2024.1464953

ISSN=1664-302X

ABSTRACT=<sec id="sec1"><title>Introduction</title><p>The cheese microbiota is very complex and is made up of technologically-relevant, spoilage, opportunistic and pathogenic microorganisms. Among them lactic acid bacteria and yeasts are the main ones. One of the most interesting dairy yeasts is <italic>Kluyveromyces marxianus</italic> because of its technological properties including the ability to produce aroma compounds.</p></sec><sec id="sec2"><title>Methods</title><p>This study investigated the contribution of <italic>Kluyveromyces marxianus</italic> to the gross composition and aroma profile of cow cheeses. Experimental cheeses were prepared by inoculating a co-culture of <italic>K. marxianus</italic> FM09 and a commercial strain of <italic>Lacticaseibacillus casei</italic> and compared with cheeses obtained with only <italic>L. casei</italic>. The gross composition was determined by a FoodScan™ 2 Dairy Analyser, and free amino acids were evaluated at 507 nm after reaction with Cd-ninhydrin. The volatile organic compounds were extracted by head-space solid phase micro-extraction and analyzed by gas chromatography–mass spectrometry coupled with odor activity values. qRT-PCR was applied to determine the expression of genes involved in esters synthesis and degradation.</p></sec><sec id="sec3"><title>Results</title><p>The inoculation of <italic>K. marxianus</italic> induced an increase of pH and a reduction of protein content of cheeses, in agreement with the stronger proteolysis detected in these cheeses. <italic>K. marxianus</italic> influenced the content of aroma compounds both quantitatively and qualitatively. In particular, an increase of higher alcohols, esters and organic acids was observed. Moreover, 12 compounds were detected only in cheeses obtained with the co-culture. These differences were in agreement with the odor activity values (OAV). In fact, only 11 compounds showed OAV &gt; 1 in cheeses obtained with the commercial strain, and 24 in those obtained with the co-culture. The qPCR analysis revealed an over expression of <italic>ATF</italic>1, <italic>EAT</italic>1, and <italic>IAH</italic>1 genes.</p></sec><sec id="sec4"><title>Conclusion</title><p><italic>Kluyveromyces marxianus</italic> could act as an important auxiliary starter for cheese production through the development and diversification of compounds related to flavor in short-aged cow cheeses.</p></sec>