Browsing by Author "Regado, Mafalda A."
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- Changes in the pool of free fatty acids in ovine, bovine and caprine milk fats, effected by viable cells and cell-free extracts of Lactococcus lactis and Debaryomyces vanrijiaePublication . Regado, Mafalda A.; Cristóvão, Betina M.; Tavaria, Freni K.; Ferreira, João Paulo; Moutinho, Carla Guimarães; Balcão, Victor; Xavier Malcata, F.Lipolysis catalysed by lipases, native or released by natural microflora in milk, plays a key role in development of aroma and flavour throughout cheese ripening. This research effort was aimed at a deeper understanding of the action of two wild strains used in traditional ewe’s milk cheesemaking in Portugal, viz. Lactococcus lactis and Debaryomyces vanrijiae. They were both tested as viable cells and cell-free extracts – using bovine, ovine and caprine milk fat emulsions as model substrates. Hydrolysis reactions were carried out at 30 and 37 °C, in the case of L. lactis and D. vanrijiae, respectively; the contents of short- and medium-chain fatty acids were determined by high pressure liquid chromatography. Our experimental results showed general trends, viz. preferential depletion of medium chain fatty acids throughout the whole reaction time. However, distinct patterns were observed towards different substrates, depending on the source and form of the biocatalyst at stake.
- Flavour development via lipolysis of milkfats: changes in free fatty acid poolPublication . Regado, Mafalda A.; Cristóvão, Betina M.; Moutinho, Carla; Balcão, Victor M.; Aires-Barros, Raquel; Ferreira, João Paulo M.; Xavier Malcata, F.Under the trade name lipolysed milkfat (LMF), concentrated cheese flavours obtained via enzymatic treatments of cheese (or other dairy substrates) have been made available in increasing numbers. In this research effort, (anhydrous) milkfats from cows, ewes and goats were used as substrates for production of cheesy flavours. Those milkfats were subjected to modifications brought about by ten different (commercial) lipases and one cutinase, and the free fatty acids released were analysed by high performance liquid chromatography. Both the degrees of hydrolysis and the free fatty acid profiles of the final products were similar to those reported for several LMF products, although specific keynotes could be pinpointed. Consequently, those milkfats may represent alternative raw materials for manufacture of cheesy flavours, while contributing to alleviate the problem derived from the increasing surplus of milkfat in Western countries.