PÃO DE MILHO: CARACTERIZAÇÃO DO PRODUTO TRADICIONAL E TENTATIVA DE MELHORAMENTO TECNOLÓGICO

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Organizational Unit

Publications

Separation and identification of neutral cereal lipids by normal phase

Publication . Rocha, João M.; Kalo, Paavo J.; Ollilainen, Velimatti; Malcata, F. Xavier

A novel method was developed for the analysis of molecular species in neutral lipid classes, using separation by normal phase high-performance liquid chromatography, followed by detection by evaporative light-scattering and electrospray ionization tandem mass spectrometry. Monoacid standards, i.e. sterol esters, triacylglycerols, fatty acids, diacylglycerols, free sterols and monoacylglycerols, were separated to baseline on microbore 3 m-silica gel columns. Complete or partial separation of molecular species in each lipid class permitted identification by automatic tandem mass spectrometry of ammonium adducts, produced via positive electrospray ionization. After optimization of the method, separation and identification of molecular species of various lipid classes was comprehensively tested by analysis of neutral lipids from the free lipid extract of maize flour.

2010Journal article

Restricted access

Microbial ecology dynamics in portuguese broa sourdough

Publication . Rocha, João M.; Malcata, F. Xavier

This research effort aimed at a better understanding of microbial phenomena taking place during time in spontaneous sourdough fermentation for broa, a traditional Portuguese bread. Unlike most microbiological studies of sourdough, viable counts obtained were not limited to Lactobacillus and yeasts, but encompassed also molds, Gram-negative rods, endospore-(non)forming Gram-positive rods and catalase-positive/negative Gram-positive cocci. This less conventional approach unveiled the ubiquitous Bacillus genus throughout spontaneous broa sourdough fermentation. Presumptive yeasts, Lactobacillus and Bacillus were found to low levels after kneading, but became dominant by the end of regular (no aeration) fermentation. They apparently inhibit undesired rods and Staphylococcus, which were found to relatively high numbers after kneading. By 24 h of fermentation, lactic acid cocci accounted for an important fraction of biodiversity, and pH decreased significantly reaching about 4.1. Aeration accelerated the microbial dynamics. In terms of total viable counts, such a long-term fermentation appeared to reach a quasistationary state.

2016Journal article

Open access