Fillet Spoto pela orientação e incentivo nas análises sensoriais. À Profa. Dra. Marília Oetterer, pelo apoio e incentivo na realização deste trabalho. Ao Instituto de Tecnologia de Alimentos (ITAL), em especial a pesquisadora Claire Sarantópoulos, pelo apoio na realização da atmosfera modificada. A Companhia Brasileira de Esterilização (CBE), pela irradiação do produto. À técnica do laboratório de laticínios Cleomar Carvalho, pela amizade, apoio e incentivo na realização deste trabalho. Aos estagiários Mário Paiva e Débora pela amizade e apoio na realização deste trabalho. v As grandes amigas Cláudia Marinho, Márcia D'vila e Nina Hagen, pela inesquecível convivência durante o mestrado.

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A dimmable high-power-factor electronic ballast is proposed in this paper. The electronic ballast is intended to feed a 100 W electrodeless fluorescent lamp (EFL) at 250 kHz. The proposed topology consists of a Ćuk converter, as power factor correction (PFC) stage, associated with a resonant half-bridge inverter, used as lamp power control (PC) stage. In this work, the integration of both stages is proposed in order to reduce the number of active switches, as well as to simplify the required driving and control circuitry for this application. The dimming system is implemented by the shared switch duty ratio control, attaining a power variation from 100 W to 42 W. The implemented topology achieved a high power factor (PF), varying between 0.984 and 0.978. The line current total harmonic distortion (THD) varied from 17.538% to 11.941%, while the measured efficiency was around 80%.

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This study was carried out to evaluate the effect of nitrogen fertilization on tillering dynamics of Alexandergrass (Urochloa plantaginea (Link) Hitch) grazed by beef heifers in a rotational stocking grazing method. The experiment was conducted in a completely randomized design following a repeated measure arrangement, three levels of nitrogen (Zero, 150 and 300kg ha-1) and two area repetition. The classification of tillers into categories (basal and axillary) showed a greater number of basal tillers, due to their higher appearance rate, in the absence of nitrogen fertilization. Nitrogen fertilization promoted higher axillary tiller density. The use of nitrogen promotes the renewal of axillary tillers of Alexandergrass, without compromising the stability of the tiller population.

The study was carried out to evaluate the forage intake and performance of beef heifers from 15 to 18 months of age, grazing on Alexandergrass (Urochloaplantaginea (Link) Hitch) fed rice bran (RB; 0, 0.5 and 1.0% body weight (BW)). The experiment consisted of a completely randomized design with repeated measurement arrangement. Rice bran increased the total dry matter (DM) intake, total crude protein intake and total digestible nutrients intake. Heifers that received 1.0% BW of RB reduced forage DM intake, increasing by 18% stocking rate (SR) and by 27% BW gain per area in comparison with the system exclusively on pasture. In the system in which the heifers were fed 0.5% BW of RB, SR and gain per area were similar to other systems. In this feeding system, we observed average daily gain 18% higher than when heifers were exclusively on pasture and gain similar to that observed when using 1.0% BW of RB. In Alexandergrass pasture it is recommended to supply 0.5% BW of RB for beef heifers from 15 to 18 months of age, to promote better productive responses compared to heifers exclusively on pasture and similar to those observed when supplying 1.0% BW of RB.

Três diferentes formulações de vinagre de folhas de videira foram elaboradas, mantendose a proporção de folhas e água, e variandose a concentração da sacarose. Realizouse análise sensorial das formulações, segundo os atributos aparência geral, cor, odor, sabor geral e acidez, além de análise química de acidez titulável. Vinagres comerciais de vinho branco e vinho tinto foram utilizados como padrões. Concluiu-se que somente a formulação com maior teor de sacarose apresentou porcentagem de ácido acético de acordo com os padrões recomendados para tais produtos. Considerando a avaliação sensorial, duas formulações não diferiram significativamente dos vinagres comerciais. Abstract Three different vinegar formulations from grapevine leaves were elaborated, maintaining the waterleaves rate and varying the saccharose concentration. Sensory evaluation of the formulations was realized by the characteristics: general appearance, color, odor, general taste and acidity, in addition to chemical analysis of titratable acidity. It was employed commercial vinegars of white wine and red wine, as standards. It was concluded that only the formulation with higher saccharose rate showed acetic acid percentage within the recommended level for this products, however, two of the formulations tested did not differ meaningfully from commercial vinegars.

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