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Leça do Bailio, Portugal

Pires E.J.,University of Minho | Teixeira J.A.,University of Minho | Branyik T.,Institute of Chemical Technology Prague | Brandao T.,UNICER Bebidas de Portugal SGPS SA | Vicente A.A.,University of Minho
Journal of the Institute of Brewing | Year: 2015

This work tested the viability of producing beer of good quality after maturation of green beer obtained by primary continuous fermentation of high-gravity wort using an airlift bioreactor with flocculated biomass. Fermentation performance of the tested setup was unique as it reached a maximum saccharide consumption rate of 9.43 g L-1 h-1 and an ethanol productivity of 3.75 g L-1 h-1. Despite the high levels of diacetyl present in the green beer, a regular maturation was able to reduce it to below threshold values in up to 15 days. It was observed that diacetyl production was strongly correlated with wort composition injected into the system, rather than with the large amount of biomass immobilized in the bioreactor (up to 727 × 106 cell mL-1). Organoleptic tests showed that the maturated beer had no major defects. © 2015 The Institute of Brewing & Distilling.

Vieira E.,University of Porto | Brandao T.,UNICER Bebidas de Portugal SGPS SA | Ferreira I.M.P.L.V.O.,University of Porto
Journal of Agricultural and Food Chemistry | Year: 2013

The present work evaluates the influence of serial yeast repitching on nucleotide composition of brewer's spent yeast extracts produced without addition of exogenous enzymes. Two procedures for disrupting cell walls were compared, and the conditions for low-cost and efficient RNA hydrolysis were selected. A HILIC methodology was validated for the quantification of nucleotides and nucleosides in yeast extracts. Thirty-seven samples of brewer's spent yeast (Saccharomyces pastorianus) organized according to the number of serial repitchings were analyzed. Nucleotides accounted for 71.1-88.2% of the RNA products; 2′AMP was the most abundant (ranging between 0.08 and 2.89 g/100 g dry yeast). 5′GMP content ranged between 0.082 and 0.907 g/100 g dry yeast. The sum of 5′GMP, 5′IMP, and 5′AMP represented between 25 and 32% of total nucleotides. This works highlights for the first time that although serial repitching influences the content of monophosphate nucleotides and nucleosides, the profiles of these RNA hydrolysis products are not affected. © 2013 American Chemical Society.

Oliveira A.P.,University of Porto | Matos R.P.,University of Porto | Silva S.T.,University of Porto | Andrade P.B.,University of Porto | And 5 more authors.
Journal of Agricultural and Food Chemistry | Year: 2013

Beverages are an ideal format to offer nutrients, specific health-promoting functionality, and desirable sensory attributes to consumers. Taking into account previous research on Spergularia rubra (L.) J. Presl & C. Presl, the aim of this work was to describe the chemistry and biochemistry associated with the production of a new iced tea base herbal beverage containing a hydroethanolic extract of this species, including both naturally occurring and added components. Phenolic compounds of S. rubra hydroethanolic extract and of the iced tea base herbal beverage were determined by HPLC-DAD. Thirty compounds, comprising nonacylated C-glycosyl flavones, C-glycosyl flavones acylated with aromatic acids, and C-glycosyl flavones acylated with aliphatic acids, were identified, being essentially represented by apigenin derivatives. Organic acids of both samples were determined by HPLC-UV, malic acid being the major one. A strong inhibition of α-glucosidase, acetylcholinesterase, and butyrylcholinesterase was observed. Furthermore, the influence of the pH of the digestive tube on the chemical composition of both extract and iced tea base herbal beverage and, consequently, on their biological activity, was assessed. In a general way, pH variation significantly decreased (p < 0.05) the metabolites content and enzymes inhibitory capacity. Nevertheless, the beverage enriched with S. rubra extract represents a valuable addition to consumer's health and nutrition, once the loss of activity is lower than the one verified for the base iced tea. Thus, the results suggest that the ingestion of this beverage could be of potential interest for several chronic disorders, particularly Alzheimer's disease. © 2013 American Chemical Society.

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