Browsing by Author "Caldeira, Ilda"
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- Aplicações de FTIRATR para controlo de qualidade de aguardentesPublication . Anjos, Ofélia; Santos, António J.A.; Estevinho, Leticia M.; Caldeira, IldaNeste trabalho pretendese demonstrar a eficácia da aplicação da técnica de espectroscopia de infravermelho com transformadas de Fourier com reflectância total atenuada (FTIRATR) para determinação rápida do teor alcoólico e do teor de vários compostos voláteis, designadamente metanol, acetaldeído e álcoois superiores em aguardentes vínicas e bagaceiras, com e sem envelhecimento. A medição dos parâmetros referidos por FTIRATR demonstrou ajustarse bem para a quantificação destes compostos, tendo sido encontrados valores de desvio residual de previsão (RPD) a variar entre 12,8 para o teor de metanol (em g/hL P.A.) e 4,1 para o teor de 2+3metil1butanol (em g/hL P.A.). Os valores do coeficiente de determinação (R2) variaram entre 99,4 % e 94,1 % respetivamente para os compostos anteriormente referidos. Neste trabalho são ainda comparados os tempos de resposta e custos de análise comparativamente à técnica de FTIRATR e métodos padrão. Os resultados mostram que é possível aplicar esta técnica como análise rápida para a determinação do teor alcoólico, do metanol, acetaldeído e álcoois superiores em aguardentes vínicas e bagaceira, com e sem envelhecimento e para alguns parâmetros os modelos apresentam robustez suficiente para serem utilizados nos laboratórios de controlo destes produtos.
- Distillation process characterization for honey spirit productionPublication . Santos, Regina; Caldeira, Ilda; Pereira, Ana Paula; Estevinho, Leticia M.; Anjos, OféliaHoney presents a higher amount of carbohydrates (60-82%) [1] mainly fructose and glucose and other minor compounds (proteins, enzymes free amino acids, essential minerals, vitamins and polyphenols). Given their higher amount of sugar, yeast could be convert them into alcohol through the process of fermentation. The more usual alcoholic beverage produced from the honey is mead, however, some spirits are also produced, but no scientific research is known in order to characterize this beverage. The aim of this work is to characterize the distillation process of honey spirit resulting from distillation of mead obtained from different honey raw material: Lavandula honey; Castanea honey and a mixture of waxes and honey resulting from the bee-keeper uncaps process. In the distillation process different fraction were collected during the time. The alcohol strength was determined by distillation and electronic densimetry. The volatile compounds of the samples (acetaldehyde; ethyl acetate; methanol; 1–propanol; 2-methyl-1-propanol; 1–butanol and isoamyl alcohols) were analysed by gas chromatography-flame ionization detection (GC-FID) [2]. The honey spirit does not present methanol in the majority of the analysed fractions or it is present in a very low quantity (<0.062 g/L) what is an advantage of this beverage in comparison with other distillates. The raw-material used in the production of the beverage as well as the distillation time has a significant effect in the composition of the fractions collected during the distillation process (Table 1). The different volatile profile suggests a different quality given the botanical origin of honey used as raw material. The production of honey spirit from waxes and honey resulting from the uncap process has a good quality.
- FT-RAMAN methodology for the monitoring of honeys' spirit distillation processPublication . Anjos, Ofélia; Santos, Regina; Estevinho, Leticia M.; Caldeira, IldaHoney spirit is an alcoholic beverage produced by fermentation followed by distillation of the honey must, which has distinct organoleptic characteristics derived mostly from the raw material used. In order to accurately monitor the quality of the product throughout the distillation process (head, heart and tail stages), FT-RAMAN spectroscopy was applied. Dark honey, light honey and honey obtained following waxes' wash was used to produce honey spirit. The pH, alcoholic strength, methanol content, acetaldehyde content, ethyl acetate content and higher alcohols content were evaluated during the distillation process. The FT-RAMAN technique was used to obtain spectral information for all fractions collected during beverage production. The results suggest that the honey spirit had good quality concerning the volatile composition and methanol was not detected in any sample. FT-RAMAN is promising for the online monitoring of the distillation process in order to improve the final quality of this beverage.
- FTIR-ATR spectroscopy applied to quality control of grape-derived spiritsPublication . Anjos, Ofélia; Santos, António J.A.; Estevinho, Leticia M.; Caldeira, IldaThe Fourier transform infrared (FTIR) spectroscopic method with attenuated total reflectance (ATR) was used for predicting the alcoholic strength, the methanol, acetaldehyde and fusel alcohols content of grape-derived spirits. FTIR-ATR spectrum in the mid-IR region (4000-400 cm -1 ) was used for the quantitative estimation by applying partial least square (PLS) regression models and the results were correlated with those obtained from reference methods. In the developed method, a cross-validation with 50% of the samples was used for PLS analysis along with a validation test set with 50% of the remaining samples. Good correlation models with a great accuracy were obtained for methanol (r 2 = 99.4; RPD = 12.8), alcoholic strength (r 2 = 97.2; RPD = 6.0), acetaldehyde (r 2 = 98.2; RPD = 7.5) and fusel alcohols (r 2 from 97.4 to 94.1; RPD from 6.2 to 4.1). These results corroborate the hypothesis that FTIR-ATR is a useful technique for the quality control of grape-derived spirits, whose practical application may improve the efficiency and quickness of the current laboratory analysis.
- Raw material influence in mead productionPublication . Santos, Regina; Pereira, Ana Paula; Estevinho, Leticia M.; Caldeira, Ilda; Anjos, OféliaHoney can be fermented to produce different types of mead given their sugar concentration [1]. Mead is a beverage produced by the alcoholic fermentation of diluted honey. This beverage present an alcoholic strength ranging between 8 – 18 % volumes [2]. The aim of this work is characterize the quality of honey mead with different kinds of raw-material: Lavandula honey; Castanea honey and a mixture of waxes and Castanea honey resulting from the beekeeper uncaps process. To produce the honey must the different raw materials was diluted with natural spring-water (37 g of honey/100 mL of water) and mixed to homogeneity. The honey must was inoculated with a commercial wine yeast Saccharomyces cerevisiae QA 23 at a concentration of 0,3 g/hL and incubated at 25 0C. Throughout the fermentation process biomass concentrations and reducing sugar of the must were regularly measured. At the end of fermentations the meads were treated with bentonite (100 g/hL). In the meads produced, °Brix, pH, total acidity and assailable nitrogen concentration were evaluated. It was observed that the yeast grow is more efficient in the Castanea honey than in the other samples. Given the results showed in Table 1 it is possible conclude that the meads produced with different raw material are similar and the differences could be attribute to the differences of honey, with different chemical composition. According to the obtained results it can be concluded that it is possible produce mead also with a mixture of waxes and honey resulting from the bee-keeper uncaps process with an important economical benefice.