Coffee and coffee by-products contain several chemical compounds of great relevance, such as chlorogenic acid (CGA), trigonelline, and caffeine. Furthermore, yeasts have been the target of studies for their use as probiotics because of their interesting biochemical characteristics. The combined administration of probiotic microorganisms with components that provide health benefits mediated by alginate encapsulation is an alternative that ensures the stability of cells and chemical compounds. In this context, the aim of this work was to co-encapsulate the probiotic yeast Kluyveromyces lactis B10 and extracts of green coffee beans, coffee silverskin, and PVA (black, green or immature, and sour coffee beans). The bioactive composition, antioxidant and antimicrobial activities of the extracts, microcapsule morphological characteristics and encapsulation efficiency, ability of the encapsulation to protect the yeast cells subjected to gastrointestinal conditions, and antioxidant activity of the microcapsules were evaluated. All the evaluated extracts showed antioxidant activity, of which PVA showed 75.7% and 77.0%, green coffee bean showed 66.4% and 45.7%, and coffee silverskin showed 67.7% and 37.4% inhibition of DPPH and ABTS^•+ radicals, respectively, and antimicrobial activity against the pathogenic bacteria E. coli, Salmonella, and S. aureus, with high activity for the PVA extract. The microcapsules presented diameters of between 1451.46 and 1581.12 μm. The encapsulation efficiencies referring to the yeast retention in the microcapsules were 98.05%, 96.51%, and 96.32% for green coffee bean, coffee silverskin, and PVA, respectively. Scanning electron microscopy (SEM) showed that the microcapsules of the three extracts presented small deformations and irregularities on the surface. The K. lactis cells encapsulated in all treatments with the extracts showed viability higher than 8.59 log CFU/mL, as recommended for probiotic food products. The addition of green coffee bean, coffee silverskin, and PVA extracts did not reduce the encapsulation efficiency of the alginate microcapsules, enabling a safe interaction between the extracts and the K. lactis cells.

Canastra cheese, an artisanal cheese produced in Serra da Canastra—Brazil, has great cultural importance. Furthermore, this cheese has nutritional and sensory attributes that make it of great economic importance. Its microbiota is composed of different bacteria and yeasts. Some yeasts already isolated by our research group have been characterized as potential probiotics. Probiotic microorganisms have garnered scientific interest, as improvements in the physical, chemical and sensory characteristics of food products have been reported when these microorganisms are used. In this context, the objective of this work was to evaluate Kluyveromyces lactis and Torulaspora delbrueckii, which were previously isolated from Canastra cheese, as autochthonous starter cultures. Canastra cheese was produced under three different conditions: (1) cheese with “Pingo” (natural starter), (2) cheese with “Pingo” + yeast mixed culture, and (3) cheese with only mixed yeast culture. The results showed that the mixed yeast inoculum significantly influenced the lactic acid bacteria population. Yeast populations remained at around 106 CFU/g after 45 days of maturation. Furthermore, cheeses containing the yeast mixed with inoculum had an initial lactose content reduced by 92.80% compared to cheese produced with “Pingo” (87.70%). The antioxidant activity, evaluated using the ABTS method, showed that cheeses containing the mixed yeast culture had higher percentages of antioxidant activity at 45 days of maturation. The texture profile of the cheeses changed over time. In general, the cheese containing the yeast mixed culture and “Pingo” and the cheese containing “Pingo” had the lowest hardness at 30 days of maturation (5245 and 5404 N, respectively). Among the volatile compounds, 3-methylbutyl octanoate, phenethyl butyrate, phenethyl propionate, isobutyl butanoate and pentyl propionate were found only in cheeses produced with yeast mixed culture. The obtained results demonstrated that the use of autochthones probiotic cultures could improve the cheese characteristics without negatively impacting the traditional physicochemical attributes of Canasta cheese.

Microbial polysaccharides are of great biotechnological and commercial interest and have wide application in the food, cosmetic and medicine industries. Exopolysaccharide (EPS) production by the yeast Cryptococcus laurentii SD7, isolated from fresh water molluscs, was studied using agro-industrial byproducts as substrates in the submerged fermentation. The Central Composite Design (CCD) 23 was used to study the influence of pH, different concentrations on sugarcane molasses and corn steep liquor (CSL), for 48 hours. According to the results, the highest EPS production occurred at the initial pH 5 and at 8.4% concentration of sugarcane molasses, which were statistically significant variable at 10% (p < 0.1). The concentration of CSL had no influence in the studied range, thus, it can be used lowest concentration (0.3%). The time course of EPS production showed that while cell growth peaked within 48 hours, the highest EPS production (6.61 g L-1) occurred at 168 hours, with a productivity of about 0.04 g L-1 h-1. The pH of the medium remained approximately constant throughout the fermentation process. The yeast C. laurentii SD7 showed great potential for EPS production at a low cost and with sustainable substrates.

Microbial polysaccharides are of great biotechnological and industrial importance due to their functional properties and wide range of applications in the food, cosmetic and pharmaceutical industries. For the microbial synthesis of polysaccharides, f by-products or agro-industrial residues has been widely used as alternative substrates to reduce production costs. In this study, we evaluated several sources of carbon (sucrose, lactose, glucose, glycerol and sugarcane molasses at 5%) and nitrogen (organic and inorganic at 1%) as substrates for the biosynthesis of exopolysaccharides (EPS) by Cryptococcus laurentii SD7. The best substrates were sugarcane molasses and the combination of (NH4)2SO4 and NaNO3 salts. To study the effect of combining these substrates and optimize EPS production, the Central Composite Design (CCD) 23 methodology was used, resulting in 17 trials, where the concentration of sugarcane molasses varied from 1% to 9% and nitrogen sources varied from 0.2% to 0.8%. The factorial design showed that NaNO3 did not affect EPS production, but sugarcane molasses and (NH4)2SO4 were effective at concentrations of 9% and 0.2%, respectively, reaching EPS production of 11.0 g L-1. The results were very promising, showing that C. laurentii SD7 has high potential for EPS production on low-cost substrates.