Mead production using immobilized cells of saccharomyces cerevisiae: Reuse of sodium alginate beads

This work studied the production of mead using second category honey and the immobilized cells of Saccharomyces cerevisiae in sodium alginate, with concentrations of 2% and 4%, and their reuse in five successive fermentations. The immobilized cells with 4% alginate beads were mechanically more stable and able to allow a greater number of reuses, making the process more economical. The fermentation’s consumption of sugars with free cells (control) and immobilized cells showed a similar profile, being completed close to 72 h, while the first use of immobilized cells finished at 96 h. The immobilized cells did not significantly influence some oenological parameters, such as the yield of the consumed sugars/ethanol, the alcohol content, the pH and the total acidity. There was a slight increase in the volatile acidity and a decrease in the production of SO2. The alginate concentrations did not significantly influence either the parameters used to monitor the fermentation process or the characteristics of the mead. Mead fermentations with immobilized cells showed the release of cells into the wort due to the disintegration of the beads, indicating that the matrix used for the yeast’s immobilization should be optimized, considering the mead production medium.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2019).info:eu-repo/semantics/publishedVersio

Aplicação de uma língua electrónica na classificação de méis monoflorais

Analisou-se o perfil polínico de 51 amostras de mel nacional. Os pólens mais frequentes no mel são originários das plantas dos géneros Lavandula, Cistus, Echium, Erica, Castanea, Thymus, Prunus, Cytisus, Carduus, Trifolium e Citrus. Considerando a classificação de mel monofloral de Lavandula (pólen predominante superior a 15%), de Erica e de Echium (pólen predominante superior a 45%) seleccionaram-se 38 méis monoflorais: 18, 9 e 11 destes méis foram classificados como méis monoflorais de Lavandula, Erica e Echium, respectivamente. Contudo há méis que podem ser classificados como mel monofloral de dois géneros de pólen (Lavandula-Echium, Erica-Lavandula, Echium-Lavandula). Os méis monoflorais foram analisados com um sistema de multi-sensores químicos não específicos de sensibilidade cruzada (Língua Electrónica) e os resultados foram tratados através da análise de componentes principais e análise discriminante. Verificou-se que é possível discriminar razoavelmente o mel monofloral de acordo com o género do pólen predominante

Effect of nitrogen supplementation on yeast fermentation performance and mead quality

Mead is a traditional drink, containing X-1 X% (v/v) of ethanol, which results from the alcoholic fermentation of diluted honey performed by yeasts. However, when it is produced in a homemade way mead producers find several problems, namely, the lack of uniformity in the final products low or premature fermentations arrest, and the production of "off-flavours" by the yeasts. These problems could be due to several factors, including lack of essential nutrients such as a deficiency in available nitrogen. Additionally , it has been reported that mead fermentation is a time-consuming process, often taking several months to complete. depending on the type of honey, yeast strain anti honey-must composition. Since mead production is a time-consuming process. to make its production viable it is necessary to reduce the fermentation time while producing an end product of quality. Thus. the aim of this study was to evaluate I he effect of nitrogen addition 10 honey-must on two active dry wine yeasts (ADWY) fermentation performance, as well as on the mead composition and volatile aroma compounds production

Effect of Saccharomyces cerevisiae cells immobilisation on mead production

Mead is a traditional alcoholic beverage obtained by the fermentation of diluted honey performed by yeasts. In this work the potential of application of immobilised yeast cells on single-layer Ca-alginate or double-layer alginateechitosan for mead production was assessed for the first time. The meads produced either with entrapped or free cells were evaluated in terms of quality and aroma profile. The immobilisation procedure had no adverse effect on cell viability, since minor differences were found in fermentation kinetics among the strains and immobilisation systems. The double-layer alginate-chitosan had no advantage compared with the single-layer Ca-alginate, as the number of free cells in the medium, resulting from cell leakage, was similar. Although meads obtained with entrapped yeast cells presented less ethanol and glycerol and more acetic acid, it exhibited larger amounts of volatile compounds. Immobilised cells produced meads with more compounds with fruity characteristics, such as ethyl octanoate and ethyl hexanoate; however the concentrations of undesirable compounds in such meads were also higher. The effect of immobilisation on the aroma profile was important, but the strain contribution was also of major importance. Thus, the sensory analysis of final product gives an important insight on the overall quality.The research presented in this paper was partially funded by the Fundacdo para a Ciencia e Tecnologia, (FCT) and by PTDC projects (contracts PTDC/AGR-ALI/68284/2006). A.P.P. is a recipient of a Ph.D. grant from the FCT (SFRH/BD/45820/2008)

Impact of inoculum size on mead aroma compounds formation by wine strains of S. cerevisiae

Mead is a traditional drink, containing 8-18% (v/v) of ethanol, which results from the alcoholic fermentation of diluted honey performed by yeasts. It has been reported that mead fermentation is a time-consuming process, and an important objective of mead makers is to reduce the fermentation time without decreasing the quality of the end product. A significant time can be saved in the fermentation process by increasing the pitching rate, i.e., the amount of suspended yeast cells added to a batch fermenter. However, an increase in the inoculum size could also have deleterious side effects on the flavour profile of the final beverage. Therefore, the aim of this study was to investigate the impact of the inoculum size of two commercial winemaking strains of Saccharomyces cerevisiae (Lalvin QA23 and Lalvin ICV D47) on the mead volatile aromatic compound production. Honey must was prepared according to the recipe developed by our team, supplemented with potassium tartrate, pH adjusted to 3.7 with malic acid and the nitrogen concentration adjusted to 267 mg/L with diammonium phosphate. The appropriate amounts of inoculum were pitched into the honey-must to obtain five different pitching rates. Mead produced was analysed for major volatile compounds by GC-FID and for minor volatile compounds by GC-MS. A total of twenty-seven fermentative aroma compounds including alcohols, esters, volatile phenols, volatile fatty acids and carbonyl compounds were identified and quantified in meads. It was observed quantitative differences in aroma profiles, confirming the contribution of both yeast strain and inoculum size on the sensory characteristics of meads. Of the twenty-seven volatile compounds quantified, fourteen could contribute to mead aroma and flavour because their concentrations rose above their respective thresholds. In general, the formation of these compounds was particularly pronounced at low pitching rates. The esters ethyl hexanoate, ethyl octanoate and isoamyl acetate were the most powerful odorants detected in all meads. In addition to this quantitative analysis of the impact of strain selection and inoculum size on mead aroma, a complementary sensorial evaluation of the meads would yield further useful information for mead producers

Insight into the sensing mechanism of an impedance based electronic tongue for honey botanic origin discrimination

Animpedance based electronictongue was developed and used to discriminate honey of different botanic origin. The e-tongue presented here is based on the small-signal frequency response of the electrical double-layer established between the honey solution and an array of four different sensing units composed by gold, carbon, indium-tin-oxide, and doped silicon. The ability of the e-tongue to discriminate honey of different floral origins was demonstrated by distinguishing honey from Bupleurum and Lavandula pollen prevalence. The honey fingerprint obtained with the e-tongue was validated by parallel melissopalenogical analysis and physico-chemical methods. It is demonstrated that the e-tongue is very sensitive to changes on the honey electrical conductivity. Small differences in electrical conductivity are introduced by the presence of ionisable organic acids and mineral salts. Moreover, we propose that the sensitivity of the tongue to changes in electrical conductivity can be explored to probe other complex liquid substances.We gratefully acknowledge financial support from the Portuguese Foundation for Science and Technology (FCT), the Instituto de Telecomunicações (UID/Multi/04326/2013), the Centro para os recursos biologicos e alimentos mediterranicos (UID/BIA/04325/2013) and the Centro de Estudos Florestais (UID/AGR/00239/2013).info:eu-repo/semantics/publishedVersio

Caracterização do espumante de mel com diferentes agentes de colagem

O espumante de mel resulta da fermentação secundária do hidromel, envolvendo a adição de levedura, sacarose, nutrientes e agentes de colagem. O objetivo deste estudo foi avaliar o efeito de diferentes agentes de colagem na composição volátil do espumante de mel (Pascoal et al., 2019). Na clarificação do espumante utilizou-se dois tipos de agentes de colagem: 1) mistura de bentonite + gelatina + albumina de ovo (CFA); 2) taninos. Foi efetuada a determinação do perfil de compostos voláteis no espumante e no hidromel que serviu de base à sua produção. A determinação dos compostos voláteis foi efetuada que por cromatografia gasosa com deteção por ionização por chama (GC-FID) e por cromatografia gasosa com espectrometria de massa (GC-MS). Foram identificados 73,2% dos compostos, sendo que: 19,1% eram álcoois; 5,5% compostos carboxílicos; 1,2% ésteres etílicos. Dos 36 compostos voláteis identificados, diferiram significativamente (p <0,05) do controlo 15 no hidromel clarificado com CFA e 10 na bebida clarificada com taninos. Os restantes 17 compostos não apresentaram diferenças significativas no espumante clarificado com CFA ou taninos. O Espumante clarificado com CFA apresentou maior valor de atividade de odor. Os resultados do perfil volátil sugerem que o espumante deve ser produzido usando diferentes concentrações de CFA.A. Pascoal agradece à FCT: SFRH/BPD/91380/2012; Agradecimentos aos seguintes projetos estratégicos da FCT: CEF - UID/AGR/00239/2019; CIMO - UID/AGR/00690/2019; CEB - UID/BIO/04469/2019.info:eu-repo/semantics/publishedVersio

Enose lab made with vacuum sampling: quantitative applications

A lab-made electronic nose (Enose) with vacuum sampling and a sensor array, comprising nine metal oxide semiconductor Figaro gas sensors, was tested for the quantitative analysis of vapor–liquid equilibrium, described by Henry’s law, of aqueous solutions of organic compounds: three alcohols (i.e., methanol, ethanol, and propanol) or three chemical compounds with different functional groups (i.e., acetaldehyde, ethanol, and ethyl acetate). These solutions followed a fractional factorial design to guarantee orthogonal concentrations. Acceptable predictive ridge regression models were obtained for training, with RSEs lower than 7.9, R2 values greater than 0.95, slopes varying between 0.84 and 1.00, and intercept values close to the theoretical value of zero. Similar results were obtained for the test data set: RSEs lower than 8.0, R2 values greater than 0.96, slopes varying between 0.72 and 1.10, and some intercepts equal to the theoretical value of zero. In addition, the total mass of the organic compounds of each aqueous solution could be predicted, pointing out that the sensors measured mainly the global contents of the vapor phases. The satisfactory quantitative results allowed to conclude that the Enose could be a useful tool for the analysis of volatiles from aqueous solutions containing organic compounds for which Henry’s law is applicable.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FED-ER under Programme PT2020 for financial support by national funds FCT/MCTES to CIMO (UID/AGR/00690/2019) and SusTEC (LA/P/0007/2020)info:eu-repo/semantics/publishedVersio

O gênero Ornithocephalus Hook. (Orchidaceae: Oncidiinae) nos estados do Paraná e Santa Catarina

O gênero Ornithocephalus Hook. (Orchidaceae: Oncidiinae) nos estados do Paraná e Santa Catarina </htm

Composite Outcomes in Observational Studies of Ulcerative Colitis: a Systematic Review and Meta‐Analysis

Background: Ulcerative colitis (UC) has been the focus of numerous observational studies over the years and a common strategy employed in their design is the use of composite and aggregate outcomes. Objective: This systematic review and meta-analysis aims to identify composite and aggregate outcomes of observational studies in UC and to evaluate how the number and type of variables included and the length of follow-up affect the frequency of patients that achieve these outcomes. Methods: A systematic literature search was carried out using MEDLINE [via PubMed], Scopus, and Web of Science online databases. Observational studies that included UC patients and reported composite or aggregate outcomes were identified. A set of variables considered to be representative of progressive or disabling UC was defined, the proportion of patients attaining the outcomes was determined and a random-effects meta-analysis was performed by dividing the identified studies into subgroups according to different criteria of interest. Results: A total of 10,264 records were identified in the systematic search, of which 33 were retained for qualitative analysis and 20 were included in the meta-analysis. The mean frequency for composite outcomes was 0.363 [95% confidence interval (CI) 0.323-0.403]. The frequency of composite outcome for the subgroup of studies that included the variable "Biologics" was significantly higher than for those in which this variable was not reported [0.410; 95% CI 0.364-0.457 versus 0.298; 95% CI 0.232-0.364; p = 0.006]. Composite outcomes were also more frequent as the follow-up duration increased. Conclusion: The frequency of composite outcomes in observational studies of UC is dependent on the specific identity of the variables being reported. Moreover, longer follow-up periods are associated with higher frequencies of composite outcomes. The evidence provided here is useful for the design of future observational studies of UC that aim to maximize the frequency of patients that achieve composite outcomes.info:eu-repo/semantics/publishedVersio