Browsing by Issue Date, starting with "2006"
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- Manufacturing of fermented goat milk with a mixed starter culture of Bifidobacterium animalis and Lactobacillus acidophilus in a controlled bioreactorPublication . Kongo, J. M.; Gomes, Ana M. P.; Malcata, F. XavierAims: This work was undertaken to study the feasibility and the characteristics of a fermented product made of goat milk, using a mixed starter culture of Bifidobacterium animalis and Lactobacillus acidophilus under controlled conditions, and to determine their survival in the fermented milk during refrigerated storage. Methods and Results: Goat milk was inoculated with Lact. acidophilus and Bif. animalis mixed starter, fermented in a glass bioreactor with controlled temperature (37 C) and anaerobiosis, and monitored for growth and acidification. The fermented milk was then stored for 10 days under refrigeration, and monitored daily for starter microflora survival and pH changes. Lact. acidophilus viable counts reached a maximum of 7Æ1 · 108 colony-forming units (CFU) ml)1, and Bif. animalis a maximum of 6Æ3 · 107 CFU ml)1 by 20 h of fermentation. During refrigerated storage, both strains exhibited a good survival, with viable numbers remaining essentially constant throughout the experiment, whereas the pH of the fermented milk dropped slightly. Conclusions: Mixed cultures of Bif. animalis and Lact. acidophilus may be used to produce fermented goat milk with high counts of both probiotic strains. Significance and Impact of the Study: Goat milk fermented with Bif. animalis and Lact. acidophilus can be manufactured as an alternative probiotic dairy product.
- Determination of mercury in fish by cold vapor atomic absorption spectrophotometry using a multicommuted flow Injection analysis systemPublication . Silva, M. Fátima; Tóth, Ildikó V.; Rangel, António O. S. S.A flow system was developed for the determination of total mercury concentration in fish samples by cold vapor atomic absorption spectrophotometry (CVAAS), based on the multicommuted flow injection analysis (MCFIA) approach. The system uses independently controlled solenoid valves for the introduction of reagents and samples. When not injected, solutions were recirculating to the reservoir bottles, in this way reducing the waste produced by the analytical system and also the sample consumption. Results were compared to those obtained by the reference flow injection procedure. Accuracy was also assessed by recovery studies using a certified reference material as well as spiked samples; recovery percentages in the range of 90.7% to 99.8% were found. The repeatability of the method was better than 6.0% (RSD, n = 10). A limit of detection of 4.8 μg of mercury per kg of fresh fish sample was achieved. The total waste produced was reduced to 30% of that from the reference flow injection CVAAS procedure.
- Um bispo precursor do Concílio: relações Igreja-Estado na obra pré-conciliar de D. António Ferreira GomesPublication . Ferreira, Manuel de Pinho
- A qualidade em serviços prestados pela internet: Managerial ReportPublication . Sousa, Rui; Oliveira, Rômulo
- A multicommuted flow injection system with a multi-channel propulsion unit: spectrophotometric determination of N-NH4+Publication . Oliveira, Sara M.; Lopes, Teresa I. M. S.; Tóth, Ildikó V.; Rangel, António O. S. S.
- As formas musicais e o mundo do valor e da espiritualidadePublication . Antunes, José Paulo
- Shared Soundscapes: A Social Environment for Collective Music CreationPublication . Costa, Joana Cunha; Barbosa, Álvaro; Coimbra, Daniela
- Saturation in autoregressive modelsPublication . Santos, Carlos; Hendry, DavidIn this paper, we extend the impulse saturation algorithm to a class of dynamic models. We show that the procedure is still correctly sized for stationary AR(1) processes, independently of the number of splits used for sample partitions. We derive theoretical power when there is an additive outlier in the data, and present simulation evidence showing good empirical rejection frequencies against such an alternative. Extensive Monte Carlo evidence is presented to document that the procedure has good power against a level shift in the last rT% of the sample observations. This result does not depend on the level of serial correlation of the data and does not require the use of a (mis-specified) location-scale model, thus opening the door to an automatic class of break tests that could outperform those of the Bai-Perron type.
- Porquê uma Agenda 21 Local?Publication . Macedo, Pedro
- Determination of nitrate and nitrite in dairy samples by sequential injection using an in-line cadmium-reducing columnPublication . Lima, M. J. Reis; Fernandes, Sílvia M.V.; Rangel, António O.S.S.A sequential injection analysis (SIA) system for the spectrophotometric determination of nitrate in dairy samples was developed. A test portion was aspirated into a carrier solution containing ethylendiaminetetracetic acid (EDTA) and ammonium buffer, which flowed into a copperized cadmium reduction column installed in-line for the determination of the nitrate plus nitrite contents of samples. For the nitrite determination, another test portion of sample was aspirated and directly sent to the detector without reduction. Nitrate content was calculated from the difference between nitrate plus nitrite (expressed as nitrite) and nitrite content. The spectrophotometric determination is based on the Griess reaction. The proposed method was used to test several dairy samples (ultrapasteurized milk with 1.7% milk fat, whey, raw bovine milk and several cheese varieties). Results were statistically in good agreement with those provided by the reference procedure, with a detection limit of 0.15 mgL 1. A sampling rate of 21 determinations per hour can be achieved with this procedure.