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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studies on the fouling of heat exchangers during the sterilisation of cows' and goats' milk

Kastanas, Pascalis January 1996 (has links)
No description available.
2

How Hot, How Deep, How Long: Constraints on the Tectono-Metamorphic Evolution of Granulite Terranes

Guevara, Victor Emmanuel 05 June 2017 (has links)
Granulites are the dense, strong metamorphic rocks that are produced during high- (HT) to ultrahigh-temperature metamorphism (UHT) and partial melting of Earth's crust. Granulites are ubiquitous in exhumed Archean cratons and are thought to comprise much of Earth's stable lower crust. Understanding the mechanisms responsible for crustal heating in Archean terranes is thus paramount to understanding the stabilisation of early continental crust, and whether such mechanisms resemble modern tectonic processes. It is therefore important to quantify the pressure–temperature–time (P–T–t) paths of Archean granulites, as such paths can be diagnostic of heating mechanism. This dissertation explores: 1) novel approaches to reconstructing the P–T–t paths of granulites, and 2) what the deciphered P–T–t paths of rocks from two Archean granulite terranes reveal about Archean crustal heating. The first chapter shows how petrologic modelling at multiple scales from a texturally heterogeneous granulite can provide "snapshots" of the P–T path, which would be difficult to reconstruct otherwise. The remaining chapters are focused on reconstructing the P–T–t paths of two Archean granulite terranes: the Beartooth Mountains, and the Pikwitonei granulite domain (PGD). The second and third chapters present evidence for cryptic HT metamorphism of the Beartooth granulites at ~2.7 Ga characterized by rapid (< 1 Ma) exhumation at HT and fast cooling (~10-100 C/Ma) in the middle crust. This suggests advective/conductive heating over short length-scales. In the fourth chapter, thermobarometric data suggest the western PGD experienced UHT decompression followed by cooling in the lower crust. High-precision zircon and monazite dates reveal apparently episodic crystallization over at least ~24 Ma. This episodicity could reflect multiple thermal cycles or the control of local reactions on zircon/monazite crystallization during cooling. High-spatial resolution petrochronology provides temporal constraints on prograde metamorphism. These data suggest metamorphism in the PGD was driven by a long-lived heat source over large length-scales near the base of the lithosphere. Disparities in the timescales, length-scales, and the depth and amount of heating between the terranes may suggest different crustal heating mechanisms in each, and that the late Archean Earth may have been tectonically diverse. / Ph. D.
3

Reaction kinetics of heat-induced quality changes in soymilk

Kwok, Kin-Chor Casey January 1997 (has links)
No description available.
4

Hodnocení kvalitativních ukazatelů mléka

Vintrlíková, Eva January 2014 (has links)
This Master's thesis is focused on evaluation of qualitative characters of cow's, sheep's and goat's milk and its different sensory quality. The theoretical part describes in detail every characters of milk as a fat, proteins, carbohydrates and also will focused on extension of quality of milk using thermo-adjustment and focused on basic sensory evaluation of certain characters, including the most frequent deviations from standard state. In the practical part is summary of results from sensory evaluation of many varieties of milk with different thermo-adjustment or following thermo-adjustment in households consecutive years 2010--2013.
5

Efeito do processo UHT (Ultra High Temperature) nas características químicas, enzimáticas e sensoriais de água de coco (Cocus nucifera l.) / Effect of UHT (Ultra High Temperature) process in chemical, enzymatic and sensory characteristics of coconut water (Cocus nucifera L.)

Sucupira, Natalia Rocha January 2016 (has links)
SUCUPIRA, Natalia Rocha. Efeito do processo UHT (Ultra High Temperature) nas características químicas, enzimáticas e sensoriais de água de coco (Cocus nucifera l.). 2016. 150 f. Tese (Doutorado em Ciência e Tecnologia de Alimentos)-Universidade Federal do Ceará, Fortaleza, 2016. / Submitted by Anderson Silva Pereira (anderson.pereiraaa@gmail.com) on 2017-01-12T19:43:44Z No. of bitstreams: 1 2016_dis_nrsucupira.pdf: 5017770 bytes, checksum: 143d330e3662de79a15b3f74734cfb97 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2017-01-19T12:03:23Z (GMT) No. of bitstreams: 1 2016_dis_nrsucupira.pdf: 5017770 bytes, checksum: 143d330e3662de79a15b3f74734cfb97 (MD5) / Made available in DSpace on 2017-01-19T12:03:23Z (GMT). No. of bitstreams: 1 2016_dis_nrsucupira.pdf: 5017770 bytes, checksum: 143d330e3662de79a15b3f74734cfb97 (MD5) Previous issue date: 2016 / The objective of this research was to study the UHT sterilization conditions of the green coconut water, avoiding the color, physical-chemical and taste changes. The work was organized into five chapters, developed in order to achieve the stipulated goals. In chapter 1 were conducted four experiments; the first was to evaluate four different binomials time X temperature (subprocessing and processing) and check the enzymatic activity and the color changes in coconut water. The second experiment aimed to analyze the use of antioxidant additives (ascorbic acid and sodium metabisulfite) in the physico-chemical enzymatic and color characteristics of coconut water. The third experiment was to investigate the change of color and the enzymatic regeneration in processing conditions and subprocessamento over 28 days storage (28°C ± 2°C). The fourth experiment evaluated the coconut water through the analysis of the global acceptance and survey descriptors. In chapter two it is used a rotational central composite design (CCRD) 23 in order to choose UHT sterilization condition with reduced enzyme activity and color change, associated with the use of sulphite. The purpose of said section was to evaluate the effect of sterilization parameters quality of coconut water after 24 hours and after 45 days storage at room temperature (28°C ± 2°C). Chapter three aimed to evaluate the physical- chemical, enzymatic and color stability of coconut water submitted to UHT sterilization (136°C/8s) in the absence and presence of 20 mg. L-1 of sulfite, during 180 days and to perform sensory analysis and commercial sterility test. With respect to chapter four, the purpose was to perform a quantitative evaluation of the primary metabolites of coconut water sterilized by UHT in the presence or absence of additive sulfite, using NMR (Nuclear Magnetic Resonance) and chemometrics. Chapter five aimed to develop blends composed of coconut water and tropical fruit pulps and assess the impact of thermal processing (pasteurization and UHT sterilization) on the functional components and the bioaccessible content after simulated digestion in vitro. As regards the conclusions of each chapter can be seen that in chapter one, the rose coconut water in subprocessing condition does not correlate with the activity of enzymes PPO and POD, polyphenol oxidase and peroxidase, respectively; the use of ascorbic acid has a yellowish coconut water, and adopted the use of sulfite in the following chapters; there was no enzymatic reactivate during 28 days of observation, in which it was in the appearance of pink in subprocessing treatments. There was no significant difference between treatments for global acceptance of sterile coconut water. About chapter two, after 45 days the color coordinate b * was positively correlated with temperature, with a tendency to yellow. There was no optimization of the sterilization process, however, the most suitable condition is the center point (135° C/9s), associated with the use of sulphite in concentrations above 20 mg. L-1. For chapter three, it was found that the coconut water sterilized by UHT showed physico-chemical and enzymatic stability. The color coordinate a * decreased and the turbidity increased over time of 180 days. As for the sensory analysis did not reveal any statistical difference between the sterilization treatment with sulphite and without sulfite. For the commercial sterility analysis, there was growth in a mesophilic treatments. Regarding the chapter four, it is concluded that the temperature was the parameter most affected the concentrations of major compounds of coconut water: glucose, sucrose, fructose, malic acid and ethanol. It was also found that lower temperatures (110°C) associated with the use of the sulfite antioxidant additive contributing to the maintenance of these compounds. As for the chapter five, it is concluded that all treatments showed statistically significant differences between the native sample and after simulating the gastrointestinal digestion in vitro, in which only about 10% to 20% of the content of functional compounds became bioaccessible. The UHT sterilized blend exhibited higher mean values bioaccessible fraction when compared to the pasteurized blend, suggesting that the sterilization condition may be advantageous with regard to total antioxidant content which became bioaccessible following gastrointestinal digestion. The results of this study indicate that the use of UHT technology associated with sulphite use was useful in the preservation of green coconut water and minimised the browning reactions, as well as revealing positive sensory acceptance. / O objetivo desta pesquisa foi estudar as condições de esterilização UHT da água de coco verde, evitando as alterações de cor, físico-químicas e de sabor. O trabalho foi organizado em cinco capítulos, desenvolvidos a fim de atingir os objetivos estipulados. No capítulo 1 foram realizados quatro experimentos; o primeiro teve como finalidade avaliar quatro diferentes binômios tempo X Temperatura (subprocessamento e processamento) e verificar a atividade enzimática e as mudanças de cor na água de coco. O segundo experimento objetivou analisar o uso de aditivo antioxidantes (ácido ascórbico e metabissulfito de sódio) nas características físico-quimicas, enzimáticas e de cor da água de coco. O experimento três objetivou investigar a mudança de cor e a regeneração enzimática nas condições de processamento e subprocessamento ao longo de 28 dias de armazenamento (28°C±2°C). O experimento quatro avaliou sensorialmente a água de coco através de análise de aceitação global e levantamento de descritores. No capítulo dois foi utilizado um Delineamento Composto Central Rotacional (DCCR) 23 com a finalidade de escolher a condição de esterilização UHT com menor atividade enzimática e alteração de cor, associada ao uso do sulfito. O objetivo do referido capítulo foi avaliar o efeito dos parâmetros de esterilização na qualidade da água de coco após 24 horas e após 45 dias de armazenamento a temperaura ambiente (28°C±2°C). O capítulo três objetivou avaliar a estabilidade físico-química, enzimática e de cor da água de coco submetida a esterilização UHT (136°C/8s), na ausência e presença de 20 mg.L-1 de sulfito, durante 180 dias, bem com o realizar análise sensorial e teste de esterilidade comercial. Com relação ao capítulo quatro, a finalidade foi realizar a avaliação quantitativa dos compostos metabólitos primários da água de coco esterilizada por UHT, na presença ou ausência do aditivo sulfito, utilizando RMN (Ressonância Magnética Nuclear) e quimiometria. O capítulo cinco teve como objetivo desenvolver blends compostos por água de coco e polpas de frutos tropicais e avaliar o impacto do processamento térmico (pasteurização e esterilização UHT) sobre os componentes funcionais e sobre o conteúdo bioacessível após digestão simulada in vitro. No que se refere às conclusões de cada capítulo, pode- se observar que no capítulo um, a água de coco apresentou uma coloração rosada na condição de subprocessamento, não se correlacionando com a atividade das enzimas PPO e POD, polifenoloxidase e peroxidase, respectivamente; o uso de ácido ascórbico tornou a água de coco amarelada, sendo adotado o uso do sulfito nos capítulos seguintes; não houve regenaração enzimática no decorrer dos 28 dias de observação, nos quais verificou-se surgimento da cor rosa nos tratamentos de subprocessamento. Não foi observada diferença significativa entre os tratamentos para a aceitação global de água de coco esterilizada. Acerca do capítulo dois, após 45 dias a coordenada de cor b* se correlacionou positivamente com a temperatura, com tendência a cor amarela. Não houve otimização do processo de esterilização, todavia a condição mais indicada foi o ponto central (135°C/9s), associada ao uso do sulfito em concentrações superiores a 20 mg.L-1 Para o capítulo três, constatou-se que a água de coco esterilizada por UHT apresentou estabilidade físico-química e enzimática. A coordenada de cor a* decresceu e a turbidez aumentou ao longo do tempo de 180 dias. Quanto à análise sensorial, não foi verificada diferença estatística entre os tratamentos de esterilização com sulfito e sem sulfito. Para a análise de esterilidade comercial, houve crescimento de mesófilas em um dos tratamentos. Com relação ao capítulo quatro, conclui-se que a temperatura foi o parâmetro que mais afetou as concentrações dos compostos majoritários da água de coco: Glicose, sacarose, frutose, etanol e ácido málico. Constatou-se também que menores temperaturas (110°C) associadas ao uso do aditivo antioxidante sulfito contribuem para a manutenção destes compostos. Quanto ao capítulo cinco, conclui-se que todos os tratamentos exibiram diferenças estatísticas significativas entre a amostra nativa e após a simulação da digestão gastrointestinal in vitro, em que somente cerca de 10% a 20% do conteúdo de compostos funcionais tornou-se bioacessível. O blend esterilizado por UHT apresentou maiores valores médios de fração bioacessível quando comparado ao blend pasteurizado, sugerindo que a condição de esterilização pode ser vantajosa no que diz respeito ao conteúdo de atividade antioxidante total que se tornou bioacessível após a digestão gastrointestinal. Os resultados encontrados neste trabalho indicam que o uso da tecnologia UHT associada ao uso de sulfito foi útil na preservação da água de coco verde e minimizou as reações de escurecimento, além de revelar aceitação sensorial positiva.
6

Incidence and characterisation of Bacillus sporothermodurans isolated from UHT milk

Tabit, Frederick Tawi 16 June 2011 (has links)
Bacillus sporothermodurans, which was first detected in UHT milk in Germany in 1990, can affect the stability and shelf life of contaminated commercial UHT milk and cause economic losses. Due to the unusual thermal resistance of B. sporothermodurans spores, B. sporothermodurans can survive UHT treatment and proceed to grow in stored products causing instability because of their proteolytic activity (Huemer et al., 1998). This study was conducted to determine the level of B. sporothermodurans contamination in South African dairies and to understand the mechanism of B. sporothermodurans spore destruction in order to investigate ways of inactivating these spores without severe heating. The objectives were to determine the presence of Bacillus sporothermodurans in retail UHT milk along with milk from different points of a processing line and isolates from UHT milk in South Africa, UP20A and a reference strain of B. sporothermodurans, DSM 10599 from Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSMZ) in Germany were characterised using PCR. The effect of chilling, pre-heating, UHT, reprocessing and H2O2, individually and in combination, on the survival of B. sporothermodurans was also investigated in broth. Spores were heated at 130 °C for 4, 8 and 12 min in order to investigate the mechanism of structural damage and survival. The adopted real time (RT) PCR with SYBR Green method was effective for the confirmation of B. Sporothermodurans. The structural damage on heated spores was determined using the Transmission Electron Microscopy (TEM), while High Performance Liquid Chromatography (HPLC) and spectrophotometry were used to quantify Dipicolinic acid (DPA) and soluble proteins released from the filtrate of heated spore suspensions. All statistical analyses were done using STATISTICA. B. sporothermodurans was detected in retail UHT milk packs from only one processor. The combination of chilling and UHT was more effective in eliminating B. sporothermodurans spores to a non detectable level than UHT treatment alone. H2O2 was also effective in eliminating B. sporothermodurans spores, from 6.31 to 1.64 log cfu/ml after 15 min of exposure and. The release of DPA during wet heat treatment coincides with visible signs of structural damage and significant inactivation of spores. Visible signs of spore structural damage emanate at different rates. The amount of protein release seems to be strain specific. This research is the first to detect the presence of B. sporothermodurans in UHT milk in South Africa and to determine the effect of UHT processing stresses on its survival. These results can be used to design processing parameters so as to effectively eliminate B. sporothermodurans spores during UHT processing. Similarly, this research is the first in which RT PCR with SYBR Green has been used to characterise B. sporothermodurans as well as to determine the effect of wet heat treatment on the structure of B. sporothermodurans spores. This research aims to contribute to the insight regarding the mechanisms of destruction of B. sporothermodurans spores by wet heat. / Thesis (PhD)--University of Pretoria, 2010. / Food Science / unrestricted
7

Avaliação da contaminação por aflatoxina M1 em leite cru e leite UHT / Evaluation of aflatoxin M1 contamination in raw milk and UHTmilk

Weigel, Michele January 2007 (has links)
A aflatoxina M1 (AFM1) é um metabólito tóxico resultante da biotransformação da aflatoxina B1 e pode ser secretada no leite de animais que ingerem alimentos contaminados com esta última. Considerando os efeitos adversos que podem ocorrer devido à ingestão do produto contaminado e visto que as crianças, maiores consumidoras deste alimento, são potencialmente mais sensíveis que os adultos aos efeitos desta micotoxina, a avaliação da presença de AFM1 no leite se faz necessária. Durante o período de março a novembro de 2006 foram analisadas 48 amostras de leite cru provenientes de 8 propriedades fornecedoras de leite para uma Cooperativa de Leite da Serra Gaúcha e 80 amostras de leite UHT, provenientes de 7 marcas distintas, comercializadas em Porto Alegre (RS). A metodologia empregada na análise de aflatoxina M1 envolveu partição líquido-líquido na etapa de extração, uso de coluna de sílica gel na etapa de purificação e Cromatografia em Camada Delgada para a detecção. O limite de detecção foi de 10 ng e a avaliação da eficiência do método apresentou valor de 86% no teste de recuperação. Nas condições de trabalho e pelo método utilizado nenhuma das amostras analisadas foi positiva para a presença de AFM1, sugerindo que as mesmas encontram-se dentro das conformidades legais. / Aflatoxin M1 (AFM1) is a toxic metabolite resulting of the biotransformation of aflatoxin B1, and may be sectreted in milk of animals that consume foods contaminated with aflatoxin B1. Considering the adverse effects that can occur when foods contaminated are consumed, and since children, the greatest milk consumer are potentially more susceptible than adults to the effects of this mycotoxin, the evaluation of the presence of AFM1 in milk is necessary. From March to November of 2006 48 samples of raw milk from 8 dairy farms that integrate a Milk Cooperative of mountain region of Rio Grande do Sul and 80 samples of UHT milk from 7 different brands commercialized in Porto Alegre were analized. The mehodology employed for the analysis of aflatoxin M1 involved liquid-liquid partition on the extraction step, use of silic gel column for the purification step and Thin Layer Chromatography for the detection. The evaluation of the method efficiency present a value of 86% in the recovery test and the detection level was 10ng. Following analysis conditions and the method employed none of the samples analyzed were positive for the presence of aflatoxin M1, suggesting that samples analysed attend the legal conformities.
8

Avaliação da contaminação por aflatoxina M1 em leite cru e leite UHT / Evaluation of aflatoxin M1 contamination in raw milk and UHTmilk

Weigel, Michele January 2007 (has links)
A aflatoxina M1 (AFM1) é um metabólito tóxico resultante da biotransformação da aflatoxina B1 e pode ser secretada no leite de animais que ingerem alimentos contaminados com esta última. Considerando os efeitos adversos que podem ocorrer devido à ingestão do produto contaminado e visto que as crianças, maiores consumidoras deste alimento, são potencialmente mais sensíveis que os adultos aos efeitos desta micotoxina, a avaliação da presença de AFM1 no leite se faz necessária. Durante o período de março a novembro de 2006 foram analisadas 48 amostras de leite cru provenientes de 8 propriedades fornecedoras de leite para uma Cooperativa de Leite da Serra Gaúcha e 80 amostras de leite UHT, provenientes de 7 marcas distintas, comercializadas em Porto Alegre (RS). A metodologia empregada na análise de aflatoxina M1 envolveu partição líquido-líquido na etapa de extração, uso de coluna de sílica gel na etapa de purificação e Cromatografia em Camada Delgada para a detecção. O limite de detecção foi de 10 ng e a avaliação da eficiência do método apresentou valor de 86% no teste de recuperação. Nas condições de trabalho e pelo método utilizado nenhuma das amostras analisadas foi positiva para a presença de AFM1, sugerindo que as mesmas encontram-se dentro das conformidades legais. / Aflatoxin M1 (AFM1) is a toxic metabolite resulting of the biotransformation of aflatoxin B1, and may be sectreted in milk of animals that consume foods contaminated with aflatoxin B1. Considering the adverse effects that can occur when foods contaminated are consumed, and since children, the greatest milk consumer are potentially more susceptible than adults to the effects of this mycotoxin, the evaluation of the presence of AFM1 in milk is necessary. From March to November of 2006 48 samples of raw milk from 8 dairy farms that integrate a Milk Cooperative of mountain region of Rio Grande do Sul and 80 samples of UHT milk from 7 different brands commercialized in Porto Alegre were analized. The mehodology employed for the analysis of aflatoxin M1 involved liquid-liquid partition on the extraction step, use of silic gel column for the purification step and Thin Layer Chromatography for the detection. The evaluation of the method efficiency present a value of 86% in the recovery test and the detection level was 10ng. Following analysis conditions and the method employed none of the samples analyzed were positive for the presence of aflatoxin M1, suggesting that samples analysed attend the legal conformities.
9

Proposta de um protocolo para avaliação sensorial de leite ultra alta temperatura / Proposal for a protocol for sensory evaluation of milk ultra - high - temperature

Batista, Taline Aparecida da Silva 28 August 2015 (has links)
Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2016-03-31T14:23:12Z No. of bitstreams: 1 texto completo.pdf: 788157 bytes, checksum: de35a2e6967028d18d6e59b587313bbd (MD5) / Made available in DSpace on 2016-03-31T14:23:12Z (GMT). No. of bitstreams: 1 texto completo.pdf: 788157 bytes, checksum: de35a2e6967028d18d6e59b587313bbd (MD5) Previous issue date: 2015-08-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Objetivou-se desenvolver um protocolo para avaliação sensorial de leite ultra alta temperatura (UAT) com teor de gordura entre 0% e 3%. Foram levantados seis atributos descritores do produto: aroma caramelizado, sabor cozido, sabor caramelizado, sabor de gordura do leite, gosto doce e gosto amargo residual. Avaliaram-se os dados experimentais de amostras de oito marcas de leite UAT semidesnatado, obtidos pelo perfil descritivo convencional, referentes aos seis atributos e submeteu-se à Análise de Componentes Principais (ACP). Constatou-se que o gosto doce e o gosto amargo residual são suficientes para avaliação do perfil descritivo convencional de leite UAT semidesnatado em experimentos futuros de mesma natureza. O gosto doce esta correlacionado com o aroma caramelizado, sabor cozido, e sabor caramelizado, portanto, explica o comportamento desses quatro atributos. Já o gosto amargo residual por estar correlacionado com sabor de gordura do leite explica seu comportamento. Doze amostras de quatro marcas de leite foram utilizadas para determinar o número de repetições por marca de leite UAT necessárias no perfil descritivo convencional para analise dos seis atributos e para definir o número de avaliadores que permita uma avaliação sensorial descritiva confiável do leite UAT. Dos seis atributos avaliados nas quatro marcas de leite UAT, por meio do estudo da repetibilidade, apenas sabor caramelizado e gosto doce na marca A e aroma caramelizado, sabor caramelizado e gosto doce na marca H apresentaram coeficiente de repetibilidade menor que 0,70. Assim necessitariam de um número maior que cinco repetições para avaliação de cada marca de leite UAT com um nível de precisão igual 90%. Como a maioria dos atributos para as marcas avaliadas obtiveram altos coeficientes de repetibilidade, recomenda-se a utilização de quatro repetições para obtenção de um nível de precisão maior que 90%. Observou-se que ao comparar os resultados de equipes com 6, 5, 4, 3 e 2 avaliadores aos resultados da equipe com sete avaliadores, por meio da ANOVA e da ACP, não foi possível formar equipes com números reduzidos de avaliadores. Por meio do estudo da repetibilidade, concluiu-se que para existir confiabilidade entre os escores da avaliação do perfil descritivo convencional de leite UAT devem ser utilizados pelo menos 10 avaliadores treinados. Propõe-se um protocolo para a avaliação do perfil sensorial descritivo convencional de leite UAT com teor de gordura entre 0% e 3% mediante a utilização de dois atributos, gosto doce e gosto amargo residual, avaliados por pelo menos 10 avaliadores treinados. O protocolo inclui procedimentos de aquisição, preparação, apresentação e avaliação das amostras de leite UAT de forma padronizada. Apresentou-se ainda uma metodologia de recrutamento, seleção e treinamento de avaliadores com materiais de referências padronizados. O protocolo para avaliação sensorial de leite UAT desenvolvido pode ser utilizado para seleção, treinamento de avaliadores e avaliação dos atributos relevantes do produto, possibilitando a padronização das técnicas entre vários laboratórios que trabalham com análise sensorial de leite UAT no Brasil. Mas para isso há necessidade de estudos para consolidação deste protocolo de avaliação sensorial como promover estudos in loco para validação em indústrias, testar o mesmo protocolo em variados locais com as mesmas amostras para verificação da reprodutibilidade dos resultados. / The main objective was to develop a protocol for sensory evaluation of UHT milk with a fat content between 0% and 3%. In order to do that, six attributes that describe the product were identified: caramelized aroma, cooked flavor, caramelized flavor, milk fat flavor, sweet taste and residual bitter taste. The experimental data related to samples of eight brands of UHT semi-skimmed milk were evaluated based on the six attributes by conventional descriptive profile method, and they were submitted to Principal Component Analysis (PCA). It was found that the sweet taste and the residual bitter taste are sufficient to evaluate the conventional descriptive profile of UHT semi-skimmed milk in similar future experiments. The sweet taste is correlated to caramelized aroma, cooked flavor and caramelized flavor, so it explains the behavior of these four attributes. Moreover, the residual bitter taste explains the milk fat flavor behaviour since one is correlated to another. Twelve samples of four milk brands were used to determine the required number of repetitions for each UHT milk brand in the conventional descriptive profile to analyze the six attributes and to set the number of judges to allow a reliable descriptive sensory evaluation of UHT milk. Among the six attributes evaluated in the four brands of UHT milk, through the repeatability study, only caramelized flavor and sweet taste in the brand A and caramelized aroma, caramel flavor and sweet taste in brand H presented coefficient of repeatability lower than 0.70. Therefore, they would require a number greater than five repetitions to evaluate each UHT milk brand with a precision level equal to 90%. Since most attributes presented high coefficient of repeatability, it is recommended four repetitions to obtain a level of precision higher than 90%. It was found that when comparing the results of teams with 6, 5, 4, 3 and 2 judges to the team's results with seven judges, using ANOVA and ACP, it was not possible to form teams with reduced numbers of judges. From the repeatability study, it was concluded that to have reliability between the evaluation scores for the conventional UHT milk descriptive profile, it should be used at least 10 trained judges. It is proposed a protocol for the evaluation of the conventional descriptive sensory profile of UHT milk with a fat content between 0% and 3% by using two attributes, sweet taste and residual bitter taste, evaluated by at least 10 trained judges. The protocol includes procurement procedures, preparation, submission and evaluation of UHT milk samples in a standardized manner. Besides that, the protocol presents a methodology for recruitment, selection and training of judges with standard reference materials. The developed protocol for sensory evaluation of UHT milk can be used for selection, training of judges and evaluation of relevant product attributes, enabling the standardization of techniques among different laboratories working with sensory analysis of UHT milk in Brazil. However, it is necessary to develop studies in order to consolidate this sensory evaluation protocol as well as to promote on-site studies to validate the protocol in industries, and to test the same protocol in various places with the same samples to verify the reproducibility of the results.
10

Comparação entre diferentes tipos de leites como diluentes para sêmen equino refrigerado

Castro, Fabiana Santos January 2014 (has links)
Dois experimentos foram conduzidos para verificar a viabilidade do uso do leite UHT como diluente para sêmen equino refrigerado. O objetivo principal deste estudo foi avaliar o uso de leite UHT nas apresentações desnatado, semidesnatado e integral como diluente de sêmen e posteriormente foi avaliada a viabilidade espermática com o uso de leite como diluente comparado a outros dois diluentes industrializados. No experimento I foram utilizados 31 ejaculados de 3 garanhões, as amostras de cada ejaculado foram diluídas em leite UHT nas apresentações integral, semidesnatado e desnatado, numa proporção de 3:1 (3 ml de diluente e 1ml de sêmen). Foram realizadas análises de viabilidade espermática com testes de motilidade espermática, vigor espermático, integridade de membrana (CFDA/PI) e funcionalidade de membrana espermática (HOST) pós-diluição, os quais foram repetidos nas amostras refrigeradas a 4ºC após 24 e 48h. Neste experimento, não foram observadas diferenças significativas entre os 3 diluentes, quanto a motilidade espermática, vigor, CFDA/PI e HOST. No entanto, houve uma diminuição na qualidade do sêmen armazenado por 48h (P < 0,01), sendo mais acentuada entre 24 e 48h de refrigeração. No experimento II foram utilizados 30 ejaculados de 3 garanhões onde, logo após a coleta do sêmen, as amostras de cada ejaculado foram diluídas com leite UHT desnatado (LD), Botusemen® (BS) e Botusemen Special® (BSP). As amostras foram examinadas a fresco, após a diluição (0h) e em resfriamento de 24h e 48h a 4°C. Foram realizados os mesmos testes de análise espermática do primeiro experimento para avaliação comparativa dos diluentes. As amostras de sêmen refrigeradas com BSP obtiveram maior porcentagem de motilidade total (51,1%) após 24h de refrigeração quando comparado aos outros dois diluentes testados, LD (45,8%) e BS (47,3%). Com base nos resultados obtidos nos dois experimentos, o leite UHT, independente da apresentação, pode ser utilizado como diluente de sêmen para as primeiras 24h de refrigeração, mantendo a viabilidade espermática adequada, sendo também de fácil acesso e manuseio. Se for necessário a manutenção do sêmen por mais de 24h, o BSP se mostrou superior em manter a qualidade do sêmen até 48h. / Two experiments were conducted to verify the feasibility of the use of UHT milk as an extender for chilled equine semen. The main objective of this study was to evaluate the use of UHT milk in skimmed, semi-skimmed and whole milk as extender for semen and subsequently assess sperm viability using milk as a diluent compared to two other industrial extenders. In the first experiment were used 31 ejaculates from 3 stallions of known fertility, samples of each ejaculate were diluted in the whole UHT milk, semi-skimmed milk and skim milk shows a ratio of 3:1 (3ml diluent and 1ml of semen). Sperm viability analyzes were performed, including sperm motility, sperm vigor, membrane integrity (CFDA/PI) functionality and sperm membrane (HOST) post-dilution tests which were repeated in the samples cooled to 4°C after 24 and 48h. In this experiment, no significant differences in sperm motility, vigor, CFDA/IP and HOST were observed among the 3 extenders. However, there was a decrease in the quality of semen stored for 48h (P < 0.01), being more pronounced between 24 and 48h of cooling. In the second experiment, 30 ejaculates from 3 stallions were used soon after collection of semen samples, each ejaculate was diluted with UHT skim milk (LD), Botusemen® (BS) and Botusemen Special® (BSP). The samples were analyzed fresh, immediately after the dilution (0h) and after cooling for 24h and 48h at 4°C. The same tests of sperm analysis used in the first experiment for comparative evaluation of extenders were performed. Semen samples cooled with BSP obtained the highest percentage of total motility (51.1%) after 24h of cooling when compared to the two other extenders tested, LD (45.8%) and BS (47.3%). Based on the results from the two experiments, UHT milk, regardless of the presentation, can be used as a diluent of semen during the first 24h of cooling maintaining adequate sperm viability and is easy to access and handle. If maintenance of semen for more than 24h is required, the BSP was superior in maintaining the quality of semen until 48h.

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