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Bee pollen as a natural antioxidant source to prevent lipid oxidation in black pudding

Publication . Anjos, Ofélia; Fernandes, Rodrigo; Cardoso, Susana M.; Delgado, Teresa; Farinha, Nelson; Paula, Vanessa B.; Estevinho, Leticia M.; Carpes, Solange T.

The antioxidant activity of bee pollen (mainly composed by Cistus ladanifer pellets) was explored in the context of black pudding production. For this purpose, three black pudding formulations comprising varying antioxidant compounds (sodium ascorbate, bee pollen and bee pollen extract) were produced. Bee pollen was characterized according to the botanical origin, antioxidant activity, total phenol and flavonoid contents and phenolic profile. Black pudding was characterized by the microbiological safety, lipid oxidation, pH, water activity and humidity at 1, 10, 21, 30 and 37 days. Sensory acceptance was evaluated on the four first periods of storage. Salmonella spp., Escherichia coli and Listeria monocytogenes were absent in all samples. Small variations on humidity and pH were observed during the black pudding's storage. Regarding lipid oxidation, it increased, on average, from 1.36 mg to 2.11 mg malondialdehyde/kg meat. Differences among the three formulations were only significant on the first days of storage. The sensory assessment did not differ between products. This study suggests that bee pollen may be used as a natural antioxidant in meat products, yet a careful labelling is essential to alert allergic consumers.

2019Journal 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

Physicochemical characterization of Lavandula spp. honey with FT-Raman spectroscopy

Publication . Anjos, Ofélia; Santos, António J.A.; Paixão, Vasco; Estevinho, Leticia M.

This study aimed to evaluate the potential of FT-Raman spectroscopy in the prediction of the chemical composition of Lavandula spp. monofloral honey. Partial Least Squares (PLS) regression models were performed for the quantitative estimation and the results were correlated with those obtained using reference methods. Good calibration models were obtained for electrical conductivity, ash, total acidity, pH, reducing sugars, hydroxymethylfurfural (HMF), proline, diastase index, apparent sucrose, total flavonoids content and total phenol content. On the other hand, the model was less accurate for pH determination. The calibration models had high r 2 (ranging between 92.8% and 99.9%), high residual prediction deviation - RPD (ranging between 4.2 and 26.8) and low root mean square errors. These results confirm the hypothesis that FT-Raman is a useful technique for the quality control and chemical properties’ evaluation of Lavandula spp honey. Its application may allow improving the efficiency, speed and cost of the current laboratory analysis.

2018Journal article

Open access

Computational intelligence applied to discriminate bee pollen quality and botanical origin

Publication . Gonçalves, Paulo J.S.; Estevinho, Leticia M.; Pereira, Ana Paula; Sousa, João M.C.; Anjos, Ofélia

The aim of this work was to develop computational intelligence models based on neural networks (NN), fuzzy models (FM), and support vector machines (SVM) to predict physicochemical composition of bee pollen mixture given their botanical origin. To obtain the predominant plant genus of pollen (was the output variable), based on physicochemical composition (were the input variables of the predictive model), prediction models were learned from data. For the inverse case study, input/output variables were swapped. The probabilistic NN prediction model obtained 98.4% of correct classification of the predominant plant genus of pollen. To obtain the secondary and tertiary plant genus of pollen, the results present a lower accuracy. To predict the physicochemical characteristic of a mixture of bee pollen, given their botanical origin, fuzzy models proven the best results with small prediction errors, and variability lower than 10%.

2018Journal article

Open access

The effects of starter culture on the biogenic amine accumulation in traditional Portuguese dry-sausages

Publication . Panov, Dimitriy; Dias, L.G.; Pereira, Ana Paula; Lopes-da-Silva, M.F.; Peres, António M.; Estevinho, Leticia M.; Dias, Teresa

Linguiça is a highly popular and appreciated traditional Portuguese dry fermented sausage. Its production involves a ripening step, which provides favorable conditions for biogenic amines formation due to microbial growth, acidification and proteolysis. The levels of biogenic amines in dry-fermented sausages are highly dependent on the type of product, producer and could even vary from batch to batch. The microbiological quality of raw materials, technological process and growth/type of microbial flora are some factors that may explain this variability. To the authors’ best knowledge, only few studies focused on the quantification of biogenic amines in Portuguese traditional sausages, reporting variable levels of accumulation, being the tyramine the most abundant followed by putrescine and cadaverine. Starter cultures have been used aiming to prevent or reduce the formation of biogenic amines during the manufacture of dry-fermented sausages. Based on the results reported in the literature, the use of starter cultures may reduce or not the biogenic amines accumulation during the fermentation of sausages. In this work, it was evaluated the influence of one commercial starter culture (Texel®ELCE Br, Danisco) on biogenic amine accumulation during manufacture process and storage. Parameters such as pH value, water activity and microbial counts were also assessed. In general the results pointed out that the starter culture inhibited the accumulation of biogenic amines (putrescine, cadaverine and tyramine) as well as the growth of S. aureus and Enterobacterias. This inhibitory effect was clear during ripening and storage periods. On the other hand the starter culture did not have a significant effect on spermidine and spermine concentrations.

2017Conference object

Open access