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Influence of fining agents on the sensorial characteristics and volatile composition of mead

Publication . Pascoal, Ananias; Oliveira, João Manuel; Pereira, A.P.; Féas, Xésus; Anjos, Ofélia; Estevinho, Leticia M.

Copyright © 2017 The Institute of Brewing & Distilling Mead, one of the oldest fermented drinks, is derived from the fermentation of diluted honey by yeasts. In the context of wine production, several procedures are applied to stabilize the beverage and to improve its organoleptic properties. This study aims to evaluate the impact of adding fining agents on the production of mead. In general, the best results were obtained for the samples containing just one fining agent instead of two combined. However, the best performance was obtained for the combined fining agents (bentonite + gelatine + egg albumin). Tannins decreased significantly the content of volatile compounds. On the other hand, silica appears to be the best fining agent, resulting in the lowest loss of volatile compounds. Thirty-six volatile compounds were determined by gas chromatograph–flame ionization detector and gas chromatography–mass spectrometry, including alcohols (42.5%), carbonyl compounds (40.4%), acetates (14.4%) and esters (1.8%). Eleven volatile compounds had odour activity values > 1, representing those with a major impact on the aroma of mead. Significant differences (p < 0.05) were found in 10 volatile compounds independently to the type of treatment used and no differences (p > 0.05) were observed for remaining compounds. Copyright © 2017 The Institute of Brewing & Distilling.

2017Journal article

Open access

Impact of fining agents on the volatile composition of sparkling mead

Publication . Pascoal, Ananias; Anjos, Ofélia; Feás, Xesús; Oliveira, José M.; Estevinho, Leticia M.

Sparkling mead is obtained by secondary fermentation of the mead involving the addition of starter yeast culture, sucrose, nutrients and fining agents. The aim of this study was to evaluate the effect of different fining agents (tannins vs combined fining agents) on the volatile composition of sparkling mead. Sparkling mead was produced from a base mead using a commercial yeast strain (Saccharomyces bayanus) and the volatile compounds were determined by gas chromatography–flame ionisation detection and gas chromatography–mass spectrometry. Thirty six volatile compounds were quantified and the major groups were alcohols (73.2%), acetates (19.1%), carbonyl compounds (5.5%) and ethyl esters (1.2%), represented by 3-methyl-1-butanol, ethyl acetate, acetaldehyde and monoethyl succinate, respectively. The remaining compounds were present at <1%. Eleven volatile compounds exhibited odour activity values >1, with ethyl octanoate and ethyl hexanoate contributing to the aroma of sparkling mead, with fruity, strawberry and sweet notes. The combined fining agents caused a marked decrease in the concentration of volatile compounds compared with tannins. In general, 3-ethoxy-1-propanol, ethyl lactate, ethyl octanoate, diethyl succinate, diethyl malate, monoethyl succinate, 2-methylpropanoic acid, hexanoic acid, octanoic acid, acetaldehyde, acetoin, furfural, benzaldehyde, 5-hydroxymethylfurfural, trans-furan linalool oxide, cis-furan linalool oxide and 4-oxo-isophorone decreased in concentration. Conversely, 1-propanol and 2-methylpropanoic acid (tannins) and ethyl butyrate (combined fining agents) increased in concentration. The remaining volatile compounds were not affected. Significant differences (p < 0.05) were found for 19 volatile compounds independently of the type of fining agents used.

2019Journal article

Open access

Review: Novel sources and functions of microbial lipases and their role in the infection mechanisms

Publication . Pascoal, Ananias; Estevinho, Leticia M.; Martins, Ivone; Choupina, Altino

Lipases belong to the family of serine hydrolases, which in turn include various esterase enzymes (E.C.3.1.1.1). They are involved in the cleavage of triacylglycerols to free fatty acids and glycerol in many important biological processes, as for instance routine metabolism of dietary triglycerides to cell signalling and inflammation. Lipases constitute a ubiquitous group of enzymes able to catalyse a number of different reactions, many of them of industrial interest. Particularly, microbial lipases exhibit a wide range of industrial applications, namely in pharmaceutical, food and detergents industry. The aim of this review is to summarize the recent achievements illustrating the importance and the versatility of microbial lipases, including their involvement in infection mechanisms.

2018Journal article

Open access

Biological activities of commercial bee pollens: antimicrobial, antimutagenic, antioxidant and anti-inflammatory

Publication . Pascoal, Ananias; Rodrigues, Sandra; Teixeira, Alfredo; Feás, Xesús; Estevinho, Leticia M.

Bee pollen is considered, since memorable times, a good source of nourishing substances and energy. The present study aimed to evaluate the biological activities of eight commercial bee pollens purchased from the market. The origin of sample A was not specified in the labeling; samples B, C, D and G were from Portugal and the remaining were from Spain. The sample E presented the highest value of phenolics (32.15 ± 2.12 mg/g) and the H the lowest (18.55 ± 095 mg/g). Sample C had the highest value of flavonoids (10.14 ± 1.57 mg/g) and sample H the lowest (3.92 ± 0.68 mg/g). All the samples exhibited antimicrobial activity, being Staphylococcus aureus the most sensitive and Candida glabrata the most resistant of the microorganisms studied. All the samples exhibited antimutagenic activity, even though some samples were more effective in decreasing the number of gene conversion colonies and mutant colonies. Regarding the antioxidant activity, assessed using two methods, the more effective was sample B. The anti-inflammatory activity, assessed using the hyaluronidase enzyme, was highest in samples B and D. Pearson’s correlation coefficients between polyphenols, flavonoids, antioxidant activity and antimicrobial activity were computed. It was also performed a discriminant analysis.

2014Journal article

Restricted access

Botanical origin, physicochemical characterization, and antioxidant activity of bee pollen samples from the northeast of Portugal

Publication . Pascoal, Ananias; Chambó, Émerson Dechechi; Estevinho, Leticia M.

Bee pollen is a beehive product that has increased the attention of both researchers and consumers. The main goal of the present study was to evaluate 69 heterofloral dried bee pollen samples harvested in two regions of the northeast of Portugal (Mogadouro and Vimioso). For such, the botanical origin of the samples and several physicochemical parameters (moisture, pH, water activity, reducing sugar, proteins, lipids, ash, fibers, carbohydrates, energy, total phenolic, and flavonoids) were evaluated and the antioxidant potential was studied. The average percentage of pollen grains from Erica spp. and Cytisus spp. was higher (p<0.05) in samples from Mogadouro, while Cistus spp., Castanea spp., and Echium spp. were more abundant in Vimioso samples. The pollen harvested in Vimioso presented higher values on proximate parameters as compared to other samples:moisture (4.61 ± 0.84%), lipids (4.94 ± 0.94%), ash (3.28 ± 0.93%), fiber (3.55 ± 1.11%), and carbohydrates (66.60 ± 3.52%).On the other hand, higher values were obtained on Mogadouro samples regarding water activity (0.41 ± 0.11), protein (26.09 ± 2.86%), total phenols (26.71 ± 6.19, expressed as mg of Gallic acid equivalents GAE/g), and antioxidant activity (assessed by b-carotene bleaching [3.35 ± 1.17mg/mL] or the free radical scavenging assay [2.98 ± 0.63mg/mL]). All bee pollen samples had a great botanical similarity, yet the dominant pollen types were different between the two regions allowing the classification of the samples according to the geographical origin.

2022Journal article

Open access