Browsing by Author "Pintado, M. M. E."
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- Acidifying and aromatic properties of enterococcus strains in ovine and bovine milksPublication . Pimentel, L. L.; Soares, J. C.; Pintado, M. M. E.; Pintado, A. I. E.; Gomes, A. M. P.; Ferreira, A. C.; Malcata, F. X.Enterococci are lactic acid bacteria present in a wide variety of dairy and other food products. Although their presence in the former has been considered an indicator of poor hygienic conditions, nowadays a number of biotechnological and probiotic useful characteristics are already known. A few compounds resulting from the bacterium metabolism contribute to the aroma of cheese. Knowledge of those components, as well as of the acidifying capacity is very important to the dairy industry, including application toward selection of strains as better starters. The aim of this research effort was to study the role of some enterococci in ovine and bovine milks, in terms of acidifying properties and aroma potential. A total of seven strains, previously isolated from traditional Portuguese cheeses, were assayed for: Enterococcus faecium 28A, E. durans 13 and E. faecalis 6 (from Serra da Estrela cheese); and E. faecium 42, E. durans 15, E. faecalis 3 and E. casseliflavus 40 (from Terrincho cheese). Sterilized ovine and bovine milks were inoculated with 2% (v/v) inoculum and incubated at 37 °C. Microbiological viable counts on M17 agar, pH and titrable acidity were determined in duplicate at 0, 1, 4 and 7 d of incubation. Free fatty acids, recognized as strong odorants in Serra da Estrela and other traditional Portuguese cheeses, were quantified in each sample using SPME – GC/MS. All strains showed similar growth patterns, either in bovine or ovine milks, and reached levels of 108 –109 cfu/ml by 1 d of incubation (except E. durans 13, which exhibited a better growth in bovine than ovine milk). An important decrease in pH was observed in both types of milk by 1 d, for all strains. The highest reduction was observed for E. casseliflavus 40 and E. durans 15 in bovine milk, and for E. faecium 42 and E. durans 13 in ovine milk. Enterococcus faecalis 6 revealed the poorest acidification power.
- Effect of preparation and processing conditions on UV absorbing properties of hydroxyapatite-Fe2O3 sunscreenPublication . Teixeira, M. A. C.; Piccirillo, C.; Tobaldi, D. M.; Pullar, R. C.; Labrincha, J. A.; Ferreira, M. O.; Castro, Paula M. L.; Pintado, M. M. E.The development of innovative, safe and non-photocatalytic sunscreens is urgently needed, as it is essential to have sunscreen filters offering appropriate UV protection without damaging the environment and/or generating free radicals when in contact with the skin. Hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HAp) when substituted with iron has UV protection properties and is not photocatalytic; HAp was used to make a sunscreen filter by treating cod fish bones in an iron-containing solution, and then calcining them at 700 degrees C. Here we present a systematic and advanced study on this material, to obtain a sunscreen with improved UV absorbing properties, Bones were treated with three different iron salts - Fe(II) chloride, Fe(II) lactate and Fe(III) nitrate - under various pH conditions. Results showed that Fe(II) chloride in basic pH led to the most effective iron inclusion, High energy ball milling or ultrasound were investigated to increase surface area and corresponding UV absorption; high energy ball milling treatment led to the best optical properties. The optimum powders were used to formulate UV protection creams, which showed Sun Protection Factor (SPF) values significantly superior to the control cream (up to 4.1). Moreover the critical wavelength (lambda(crit)) was >370 nm (388-389 nm) and UVA/UVB ratios were very close to 1. With these properties these sunscreens can be classified as broad UV protectors. Results also showed that combining these powders with other sunscreens (i.e. titanium dioxide), a synergic effect between the different components was also observed. This investigation showed that HAp-based sunscreens of marine origin are a valid alternative to commercial products, safe for the health of the customers and, being non-photocatalytic, do not pose a threat to the environment.
- Exopolysaccharide production by lactobacillus acidophilus for potential applications in fresh cheesePublication . Pintado, A. I. E.; Truszkowska, K.; Pintado, M. M. E.; Gomes, A. M. P.; Malcata, F. X.Many strains belonging to the group of lactic acid bacteria (LAB) produce exopolysaccharides (EPS). The ability of EPS to act as viscosifying, stabilizing, and/or water-binding agents in various foods makes it an effective natural alternative to commercial synthetic stabilizers, so it may play an important role in the dairy industry. In fact, EPS-producing LAB are not only important in manufacture of yoghurt and fermented milks, but also in cheese production. Recent research efforts have shown that EPS cultures are useful to increase moisture retention and improve functional properties of low-fat Mozzarella cheese and whey cheese. In this work, the ability of Lb. acidophilus to produce EPS, and the performance of two different methods for EPS isolation was investigated. Fermentations were carried out in a Braun Biostat B 2-L fermentor, filled with 1.5 L of MRS broth containing 20 g/L lactose. The yield of the EPS isolation method was tested by adding xanthan gum to the medium. The experiments were carried out at 37 °C, 150 rpm, pH 5.5 under an N2 atmosphere. A 50 mL/L standard inoculum was prepared from a subculture of Lb. acidophilus, previously grown in the corresponding medium for 20 h at 37 °C, and was used to start-up every fermentation batch. Fermentation batches took 48 h, and samples were taken periodically. Growth was monitored spectrophotometrically and by plate enumeration. To optimise EPS isolation, cells and residual polypeptides were removed by centrifugation (4000 rpm for 20 min) upon precipitation via two different processes: addition of pronase E solution and one volume of 20 % trichloroacetic acid, or precipitation with 20 g/kg 5-sulfosalysilic acid. The EPS was precipitated by three volumes of cold ethanol and was collected by centrifugation. The weight of isolated and dried polymers was measured, and the total amount of carbohydrates was determined by the phenol-sulphuric method. Exponential growth took place for ca. 12 h, and EPS was produced mainly during the stationary phase.
- Extraction and characterisation of apatite- and tricalcium phosphate-based materials from cod fish bonesPublication . Piccirillo, C.; Silva, M. F.; Pullar, R. C.; Braga da Cruz, I.; Jorge, R.; Pintado, M. M. E.; Castro, P. M. L.Apatite- and tricalcium phosphate-based materials were produced from codfish bones, thus converting a waste by-product from the food industry into high added-valued compounds. The bones were annealed at temperatures between 900 and 1200 degrees C, giving a biphasic material of hydroxyapatite and tricalcium phosphate (Ca-10(PO4)(6)(OH)(2) and beta-Ca(PO4)(3)) with a molar proportion of 75:25, a material widely used in biomedical implants. The treatment of the bones in solution prior to their annealing changed the composition of the material. Single phase hydroxyapatite. chlorapatite (Ca-10(PO4)(6)Cl-2) and fluorapatite (Ca-10(PO4)(6)F-2) were obtained using CaCl2 and NaF solutions, respectively. The samples were analysed by several techniques (X-ray diffraction, infrared spectroscopy, scanning electron microscopy and differential thermal/thermogravimetric analysis) and by elemental analyses, to have a more complete understanding of the conversion process. Such compositional modifications have never been performed before for these materials of natural origin to tailor the relative concentrations of elements. This paper shows the great potential for the conversion of this by-product into highly valuable compounds for biomedical applications, using a simple and effective valorisation process.
- Improvement of whey cheese matrices via incorporation of Lactobacillus acidophilus — proteolytic and glycolytic activities and their impact upon sensory analysisPublication . Pintado, A. I. E.; Araújo, J. C. C.; Pintado, M. M. E.; Gomes, A. M. P.; Malcata, F. X.Requeijão is a highly nutritious soft Portuguese whey cheese, yet with such organoleptic limitations as poor flavour and grainy texture. Furthermore, it offers excellent conditions for survival and growth of lactic acid bacteria, owing to its high water activity, pH above 5.0 and low salt content. The objective of this research effort was thus to study the contribution of Lactobacillus acidophilus LAC 1 to the improvement of the organoleptic quality of Requeijão, via its proteolytic and glycolytic activities. Experimental whey cheese matrices were produced, and subsequently inoculated with L. acidophilus; these matrices, as well as a control curd, were stored at 7 °C, and samples were taken at 0, 2, 7, 14 and 21 d. Cell viability, pH, and fat, protein and moisture contents were assessed. The contents of water-soluble nitrogen (WSN), nitrogen soluble in 12 %(w/v) trichloroacetic acid (TCA) and nitrogen soluble in 5 %(w/v) phosphotungstic acid (PTA), as well as of lactose and organic acids were also determined. Sensory analysis was finally performed, using a five-point scale for the various attributes. L. acidophilus viable cells number remained constant up to 21 d, while pH decreased by ca. 0,6; this was consistent with an increase in lactic acid content up to 28 mg/g of whey cheese. Values of TCA and PTA in L. acidophilus matrices indicated relevant proteolytic breakdown of whey proteins. These matrices received the highest overall preference scores in sensory evaluation.
- Light induced antibacterial activity and photocatalytic properties of Ag/Ag3PO4 -based material of marine originPublication . Piccirillo, C.; Pinto, R. A.; Tobaldi, D. M; Pullar, R. C.; Labrincha, J. A.; Pintado, M. M. E.; Castro, P. M. L.Fish bones were converted into materials consisting of silver phosphate (Ag3PO4), beta-calcium phosphate (beta-Ca-3(PO4)(2), beta-TCP) and hydroxyapatite (Ca-10(PO4)(6)(OH)(2), HAp), as well as of metallic silver (Ag-0), with a simple treatment in solution and calcination (650 or 1000 degrees C). The antibacterial activity of the material was measured in the dark and under UV and white light irradiation; this is the first time that an Ag3PO4-based material was tested under these conditions. Results showed light-enhanced antibacterial properties toward Gram-positive and Gram-negative strains (Methicillin-resistant Staphylococcus aureus -MRSA, Escherichia coli,Pseudomonas aeruginosa), with inactivation rates of up to 99.999% under UV light, and 99% for E. coli under white light (artificial indoor lighting). The photocatalytic activity was also tested, and the degradation of methylene blue dye was observed under both UV and white light. Even if the MB degradation was to a smaller extent under white light, it was approximately twice that of the commercial photocatalyst P25. This work demonstrates the valorisation of a food industry by-product such as fish bones to form a potentially valuable material, with important applications in self sterilizing surfaces and environmental remediation.