Volatile compounds for biotechnological applications produced during competitive interactions between yeasts and fungi.

Fungi, yeasts and bacteria produce volatile compounds during their metabolism. In this study, the volatile compounds produced by yeast strains (Saccharomyces cerevisiae and Rhodotorula mucilaginosa) and fungal strains (Aspergillus carbonarius and Aspergillus ochraceus) during competitive interactions were investigated by solid-phase microextraction coupled with gas chromatography-mass spectrometry. Fifty-six volatile compounds were identified representing alcohols, aldehydes, esters, ketones, aromatic compounds, acids, furans, phenols, and nitrogen compounds, being the largest amount in the class of esters and alcohols. Eight compounds were identified only in interactive culture conditions such as 2-amino-1-propanol, isopropylamine, dimethylamine, pentyl propanoate, ethyl-2-aminopropanoate, acetone, oxalic acid, and ß-elemene and five of these were produced in cocultures including A. carbonarius. These will be developed for future biotechnological applications such as in the pharmaceutical and biological industry to produce drugs. Antimicrobial and antifungal activities; Solvent and herbicide; flavoring ingredient; solvent, plastic synthesis, nail polish remover and thinner, pesticide and herbicide; important in the complexation of minerals in the soil; and plant-environment interactions, defending predators, pathogens, and competitors.

Impact of lead (Pb2+) on the growth and biological activity of Serratia marcescens selected for wastewater treatment and identification of its zntR gene-a metal efflux regulator.

Microorganisms isolated from contaminated areas play an important role in bioremediation processes. They promote heavy metal removal from the environment by adsorbing ions onto the cell wall surface, accumulating them inside the cells, or reducing, complexing, or precipitating these substances in the environment. Microorganism-based bioremediation processes can be highly efficient, low-cost and have low environmental impact. Thus, the present study aimed to select Pb2+-resistant bacteria and evaluate the growth rate, biological activity, and the presence of genes associated with metal resistance. Serratia marcescens CCMA 1010, that was previously isolated from coffee processing wastewater, was selected since was able to growth in Pb2+ concentrations of up to 4.0 mM. The growth rate and generation time did not differ from those of the control (without Pb2+), although biological activity decreased in the first hour of exposure to these ions and stabilized after this period. The presence of the zntR, zntA and pbrA genes was analysed, and only zntR was detected. The zntR gene encodes a protein responsible for regulating the production of ZntA, a transmembrane protein that facilitates Pb2+ extrusion out of the cell. S. marcescens CCMA 1010 demonstrated a potential for use as bioindicator that has potential to be used in bioremediation processes due to its resistance to high concentrations of Pb2+, ability to grow until 24 h of exposure, and possession of a gene that indicates the existence of mechanisms associated with resistance to lead (Pb2+).

Self-induced anaerobiosis coffee fermentation: Impact on microbial communities, chemical composition and sensory quality of coffee.

Microbial communities associated with coffee fermentation have been widely investigated. However, few reports about self-induced anaerobiosis fermentation (SIAF) on microbial diversity and the chemical and sensory profile of coffees grown under different environmental conditions have been studied. This study evaluated the microbial, chemical, and sensorial profile of the natural and pulped coffee fermented with and without induced anaerobiosis. The microbial diversity was determined by plating and next-generation sequencing, the chemical profile through 1H NMR and chemometrics analysis, and sensory analysis was conducted by Temporal Dominance of Sensations (TDS). Three hundred and eighty microorganisms were isolated; 149 mesophilic bacteria, 147 lactic acid bacteria, and 84 yeasts. Hanseniaspora uvarum, Lactiplantibacillus plantarum, Leuconostoc mesenteroides, and Weissella cibaria were identified in Monte Carmelo, Três Pontas, Carmo de Minas, and Lajinha in Minas Gerais, Brazil. New generation sequencing (NGS) analysis identified a high yeast species diversity (74). Some metabolites such as chlorogenic acid, sucrose, lactic acid, and trigonelline were identified in fermented coffees with the joint analysis of NMR and the loadings of PC1. Monte Carmelo coffees processed by the pulped method stood out sensorially showed a higher dominance rate for woody, herbaceous and fruity attributes. The SIAF positively impacts microbial behavior, resulting in coffees with a more intensified fruity attribute.

The use of mesophilic and lactic acid bacteria strains as starter cultures for improvement of coffee beans wet fermentation.

The use of starter cultures during food fermentation aims to standardize the process and to obtain a higher quality product. The objectives were to study mesophilic bacteria (MB) and lactic acid bacteria (LAB) isolated from wet coffee processing and evaluate their performance in a pulped coffee medium. Eighty-six bacteria isolates (59 MB and 27 LAB) were assessed for pectinolytic activity, metabolite production, and pH value decrease in coffee-based culture (CPM). Seven bacteria strains (3 MB and 4 LAB) were selected and used as starter cultures in the wet fermentation of pulped coffee. The MB and LAB populations varied from 4.48 to 8.43 log CFU g-1 for MB and 3.54 to 8.72 log CFU g-1 for LAB during fermentation. Organic acid concentration (ranged from 0.01 to 0.53 for succinic acid; 0.71 to 8.14 for lactic acid and 0.06 to 0.29 for acetic acid), and volatile compounds (44 compounds were detected in green beans and 98 in roasted beans) were evaluated during fermentation. The most abundant compounds found in roasted beans belong to furans [15], ketones and esters [14], pyridines [13], and pyrazines [12]). Leuconostoc mesenteroides CCMA 1105 and Lactobacillus plantarum CCMA 1065 presented volatile compounds important for coffee aroma. Isovaleric acid; 2,3-butanediol; phenethyl alcohol; ß-linalool; ethyl linoleate; and ethyl 2-hydroxypropanoate could improve cupping qualities.

Production of coffee (Coffea arabica) inoculated with yeasts: impact on quality.

BACKGROUND: The aim of this study was to evaluate the performance of yeasts Saccharomyces cerevisiae CCMA 0200 and Torulaspora delbrueckii CCMA 0684 in Mundo Novo and Catuaí varieties processed by the wet method and the impact on sensory quality and compounds profile. The microbiota was evaluated by surface plating, and the compounds were evaluated by high-performance liquid chromatography and gas chromatography-mass spectrometry. Sensorial analysis was performed using the cupping test (Specialty Coffee Association). RESULTS: T. delbrueckii CCMA 0684 was better adapted to the process and remained for up to 72 h of drying. Eighteen volatile compounds were detected in green coffee and 75 in roasted coffee. 2-Furanmethanol propanoate and 2-ethyl-3,5-dimethylpyrazine were identified only in the inoculated treatments, and these are important contributors to the coffee aroma. All treatments received scores greater than 80 in the sensory analysis. CONCLUSION: T. delbrueckii CCMA 0684 presented better results in relation to the sensorial analysis and is preferable for the varieties and processing method studied. The use of starter cultures is a viable method with which to obtain high-quality coffees with a distinct flavor and thus add to value to the product. © 2019 Society of Chemical Industry.

Impact of different fermentation times on the microbiological, chemical, and sensorial profile of coffees processed by self-induced anaerobiosis fermentation.

Variation in fermentation time may be an essential alternative to provide coffee beverages with different and unique sensory profiles. This work investigated the microbiological, chemical, and sensory changes in coffees submitted to different fermentation durations (0, 24, 48, 72, and 96 h). Self-induced anaerobiosis fermentation (SIAF) was used, and two treatments were performed: spontaneous fermentation and inoculation with S. cerevisiae CCMA0543. Microbiological analyses were performed, and the permanence of the inoculum was monitored. Chromatography (sugars, organic acids, and volatile compounds) was analyzed, and sensory analysis (temporal dominance of sensations - TDS) was performed. A total of 228 isolates were identified during spontaneous fermentation. The dominant bacteria and yeasts were Leuconostoc mesenteroides, Lactiplantibacillus plantarum, Staphylococcus warneri, Bacillus sp., Torulaspora delbrueckii, Hanseniaspora uvarum, and Meyerozyma caribbica. High concentrations of citric (18.67 mg.g- 1) and succinic (5.04 mg.g- 1) acids were detected at 96 h in SIAF fermentation. One hundred twenty-one volatile compounds were detected, but 22 were detected only in inoculated coffees. In spontaneous fermentation, 48 h of fermentation showed woody notes, while 72 h showed chestnuts. However, in the inoculated coffee, 72 h of fermentation showed high fruity dominance, and 96 h of fermentation was the only one with herbaceous notes. In addition, yeast inoculation increased the intensity of caramel notes in the first 48 h and increased the fruity flavor after 72 h of fermentation. Therefore, the type of fermentation (with or without inoculation) and the chosen fermentation time will depend on the sensorial profile the producer intends to obtain.

Behavior of yeast inoculated during semi-dry coffee fermentation and the effect on chemical and sensorial properties of the final beverage.

Pulped Mundo Novo and Ouro Amarelo coffee beans were inoculated with Saccharomyces cerevisiae (CCMA 0200 and CCMA 0543) during semi-dry coffee fermentation and compared with a non-inoculated control. Samples were collected throughout the fermentation process (12days) to evaluate the persistence of the inoculum by Real-Time quantitative PCR (qPCR). Also, the chemical composition of the beans was determined by HPLC and GC-MS and the roasted beans were sensorial evaluated using the cupping test. S. cerevisiae CCMA 0543 had an average population of 5.6logcell/g (Ouro Amarelo cultivar) and 5.5logcell/g (Mundo Novo cultivar). Citric, malic, succinic and acetic acid were found in all samples, along with sucrose, fructose, and glucose. There were 104 volatile compounds detected: 49 and 55 in green and roasted coffee, respectively. All coffee samples scored over 80 points in the cupping test, indicating they were specialty-grade. Inoculation with the CCMA 0543 strain performed better than the CCMA 0200 strain. This is the first time that qPCR has been used to assess the persistence of the inoculated strains populations during coffee processing. Strain CCMA 0543 was the most suitable as an inoculant due to its enhanced persistence during the process and number of volatile compounds produced.