A comparative study on the potential of epiphytic yeasts isolated from tropical fruits to produce flavoring compounds

Abstract

In recent years, there has been an increasing interest in identifying and characterizing the yeast flora associated with diverse types of habitat because of the many potential desirable technological properties of these microorganisms, especially in food applications. In this study, a total of 101 yeast strains were isolated from the skins of tropical fruits collected in several locations in the South West Indian Ocean. Sequence analysis of the D1/D2 domains of the large subunit (LSU) ribosomal RNA gene identified 26 different species. Among them, two species isolated from the skins of Cape gooseberry and cocoa beans appeared to represent putative new yeast species, as their LSU D1/D2 sequence was only 97.1% and 97.4% identical to that of the yeasts Rhodotorula mucilaginosa and Candida pararugosa, respectively. A total of 52 Volatile Organic Compounds (VOCs) were detected by Head Space Solid Phase Micro Extraction coupled to Gas Chromatography and Mass Spectroscopy (HS-SPME-GC/MS) from the 26 yeast species cultivated on a glucose rich medium. Among these VOCs, 6 uncommon compounds were identified, namely ethyl but-2-enoate, ethyl 2-methylbut-2-enoate (ethyl tiglate), ethyl 3-methylbut-2-enoate, 2-methylpropyl 2-methylbut-2-enoate, butyl 2-methylbut-2-enoate and 3-methylbutyl 2-methylbut-2-enoate, making them possible yeast species-specific markers. In addition, statistical methods such as Principal Component Analysis allowed to associate each yeast species with a specific flavor profile. Among them, Saprochaete suaveolens (syn: Geotrichum fragrans) turned to be the best producer of flavor compounds, with a total of 32 out of the 52 identified VOCs in its flavor profile.

Effectiveness of convective drying to conserve indigenous yeasts with high volatile profile isolated from algerian fermented raw bovine milk (Rayeb)

“…These volatiles are mostly responsible for the flowery and fruity aroma. Grondin et al (2015) also described this yeast for production of alcohol and esters compounds. During fermentation, intracellular enzyme catalyzed reactions responsible of the formation of esters (Verstrepen et al, 2003).…”

“…Yeasts isolated from fermented milk are with high potential desirable technological properties especially in food applications (Grondin et al, 2015). According to the earlier studies showing high performance of S. suaveolens and W. anomalus to produce flavors (Grondin et al, 2015;de Dliveira et al, 2013), they were chosen for conservation by freeze-drying, spray-drying and convective air drying respectively.…”

“…According to the earlier studies showing high performance of S. suaveolens and W. anomalus to produce flavors (Grondin et al, 2015;de Dliveira et al, 2013), they were chosen for conservation by freeze-drying, spray-drying and convective air drying respectively. Freeze-drying and spray-drying are used to conserve potential microorganisms with industrial uses (Miyamoto-Shinohara et al, 2006;Abadias et al, 2005;Cerrutti et al, 2000).…”

Pichia cactophila and Kluyveromyces lactis are Highly Efficient Microbial Cell Factories of Natural Amino Acid-Derived Aroma Compounds

“…The leading role within this area has been usually assigned to food-habitat-related Saccharomyces cerevisiae , a species having pivotal role in foodstuff production, contributing importantly to organoleptic properties of the foods [ 3 ]. However, along with the growing amount of knowledge accumulated on this subject, it became obvious that the other yeast species play an equally important role in development of unique aromas of the food commodities [ 2 , 4 ]. The definition of the so-called “non-conventional” yeast (NCY) species, differs between individual reports on this subject [ 5 , 6 ], but most agree to assign this term to non- S. cerevisiae strains.…”

“…The definition of the so-called “non-conventional” yeast (NCY) species, differs between individual reports on this subject [ 5 , 6 ], but most agree to assign this term to non- S. cerevisiae strains. This growing awareness of the pivotal role of NCYs in development of unique and desired aroma profiles of foods and beverages has inspired endeavors aiming at isolation and screening of the yeasts for their aroma-producing potential [ 4 , 7 , 8 , 9 ]. The food-related environments are the preferred source of microbial isolates, as they usually ensure isolation of safe microbiota.…”