Unraveling the potential nutritional benefits of fermented date syrup waste: Untargeted metabolomics and carbohydrate metabolites of in vitro digested fraction

Valorization of fruit by-products is a crucial area of research for the development of innovative bio-based products. This study investigated the physicochemical properties and health-promoting benefits of date syrup waste, both fermented by Pichia cecembensis or Pichia kudriavzevii (FDSW), and unfermented (CDSW). Metabolomics profiles of these samples were identified post in vitro digestion. FDSW exhibited 42 volatile compounds, including 9 new ones, and contained (-)-epicatechin, tyrosol, and gallic acid. Bioaccessible fractions of FDSW demonstrated substantial α-amylase inhibition, with percentages of 40.7 % and 53.9 %, respectively. FDSW displayed superior cytotoxicity against Caco2 and MCF-7 cancer cell lines, with an average of ∼75 % and 56 %, respectively. Untargeted metabolomics analysis revealed an increase in secondary metabolites, totaling 27 metabolites. LC-QTOF analysis of bioaccessible carbohydrate metabolites in FDSW identified two phytochemical groups, alkaloids, and terpenoids. This study underscores the potential of FDSW for producing value-added bio-based products with desirable characteristics and health benefits.

In Vitro Characterization and Identification of Potential Probiotic Yeasts Isolated from Fermented Dairy and Non-Dairy Food Products

This study is about the isolation of yeast from fermented dairy and non-dairy products as well as the characterization of their survival in in vitro digestion conditions and tolerance to bile salts. Promising strains were selected to further investigate their probiotic properties, including cell surface properties (autoaggregation, hydrophobicity and coaggregation), physiological properties (adhesion to the HT-29 cell line and cholesterol lowering), antimicrobial activities, bile salt hydrolysis, exopolysaccharide (EPS) producing capability, heat resistance and resistance to six antibiotics. The selected yeast isolates demonstrated remarkable survivability in an acidic environment. The reduction caused by in vitro digestion conditions ranged from 0.7 to 2.1 Log₁₀. Bile salt tolerance increased with the extension in the incubation period, which ranged from 69.2% to 91.1% after 24 h. The ability of the 12 selected isolates to remove cholesterol varied from 41.6% to 96.5%, and all yeast strains exhibited a capability to hydrolyse screened bile salts. All the selected isolates exhibited heat resistance, hydrophobicity, strong coaggregation, autoaggregation after 24 h, robust antimicrobial activity and EPS production. The ability to adhere to the HT-29 cell line was within an average of 6.3 Log₁₀ CFU/mL after 2 h. Based on ITS/5.8S ribosomal DNA sequencing, 12 yeast isolates were identified as 1 strain for each Candidaalbicans and Saccharomyces cerevisiae and 10 strains for Pichia kudriavzevii.

Assessment of Yeasts as Potential Probiotics: A Review of Gastrointestinal Tract Conditions and Investigation Methods

Probiotics are microorganisms (including bacteria, yeasts and moulds) that confer various health benefits to the host, when consumed in sufficient amounts. Food products containing probiotics, called functional foods, have several health-promoting and therapeutic benefits. The significant role of yeasts in producing functional foods with promoted health benefits is well documented. Hence, there is considerable interest in isolating new yeasts as potential probiotics. Survival in the gastrointestinal tract (GIT), salt tolerance and adherence to epithelial cells are preconditions to classify such microorganisms as probiotics. Clear understanding of how yeasts can overcome GIT and salt stresses and the conditions that support yeasts to grow under such conditions is paramount for identifying, characterising and selecting probiotic yeast strains. This study elaborated the adaptations and mechanisms underlying the survival of probiotic yeasts under GIT and salt stresses. This study also discussed the capability of yeasts to adhere to epithelial cells (hydrophobicity and autoaggregation) and shed light on in vitro methods used to assess the probiotic characteristics of newly isolated yeasts.