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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

Essays on Choice and Demand Analysis of Organic and Conventional Milk in the United States

Alviola IV, Pedro A. 2009 December 1900 (has links)
This dissertation has four interrelated studies, namely (1) the characterization of milk purchase choices which included the purchase of organic milk, both organic and conventional milk and conventional milk only; (2) the estimation of a single-equation household demand function for organic and conventional milk; (3) the assessment of binary choice models for organic milk using the Brier Probability score and Yates partition, and (4) the estimation of demand systems that addresses the censoring issue through the use of econometric techniques. In the first paper, the study utilized the estimation of both multinomial logit and probit models in examining a set of causal socio-demographic variables in explaining the purchase of three outcome milk choices namely organic milk, organic and conventional milk and conventional milk only. These crucial variables include income, household size, education level and employment of household head, race, ethnicity and region. Using the 2004 Nielsen Homescan Panel, the second study used the Heckman two-step procedure in calculating the own-price, cross-price, and income elasticities by estimating the demand relationships for both organic and conventional milk. Results indicated that organic and conventional milk are substitutes. Also, an asymmetric pattern existed with regard to the substitution patterns of the respective milk types. Likewise, the third study showed that predictive outcomes from binary choice models associated with organic milk can be enhanced with the use of the Brier score method. In this case, specifications omitting important socio-demographic variables reduced the variability of predicted probabilities and therefore limited its sorting ability. The last study estimated both censored Almost Ideal Demand Systems (AIDS) and Quadratic Almost Ideal Demand System (QUAIDS) specifications in modeling nonalcoholic beverages. In this research, five estimation techniques were used which included the usage of Iterated Seemingly Unrelated Regression (ITSUR), two stage methods such as the Heien and Wessells (1990) and the Shonkwiler and Yen (1999) approaches, Generalized Maximum Entropy and the Dong, Gould and Kaiser (2004a) methods. The findings of the study showed that at various censoring techniques, price elasticity estimates were observed to have greater variability in highly censored nonalcoholic beverage items such as tea, coffee and bottled water.
2

Perfil tecnológico de cepas de bifidobactéria em cultura pura e em co-cultura com Streptococcus thermophilus em leites orgânico e convencional / Technological profile of bifidobacteria strains in pure culture and in co-culture with Streptococcus thermophilus in organic and conventional milks

Ana Carolina Rodrigues Florence 27 March 2009 (has links)
A crescente preocupação com tecnologias sustentáveis e a procura de novos alimentos funcionais despertam o interesse para o desenvolvimento de novos produtos alimentícios que proporcionem, além da nutrição, benefícios à saúde do consumidor. Assim, esse trabalho visa propor o leite orgânico como potencial matéria-prima para a fabricação de leites fermentados probióticos. Para tanto, estudou-se o perfil tecnológico de cepas de bifidobactéria em cultura pura e em co-cultura com Streptococcus thermophilus em leites orgânico e convencional, analisando a composição química dos leites, determinando o perfil de acidificação de quatro cepas de Bifidobacterium animalis subsp. lactis em cultura pura e em co-cultura com Streptococcus thermophilus, verificando a contagem microbiológica das culturas probióticas e iniciadoras nos leites fermentados, examinando o perfil de ácidos graxos e o teor de ácido linoléico conjugado dos leites fermentados e determinando o perfil de textura dos leites fermentados. A maior velocidade de acidificação foi observada para as cepas B94 e BL04 em leite orgânico e para a cepa HN019, para ambos os tipos de leite. As contagens de todas as cepas de B. animalis subsp. lactis foram superiores a 8,58 log10 unidades formadoras de colônia (UFC).mL-1</SUP. O leite orgânico apresentou maiores teores de ferro e proteína, enquanto o leite convencional apresentou maiores teores de gordura e lactose. Os principais ácidos graxos foram pouco influenciados pelo tipo de leite e as maiores quantidades de ácido linoléico conjugado (65 % maior do que o controle) foram encontradas em leite orgânico fermentado com a cepa BB12 em co-cultura com S. thermophilus. Assim, verificou-se que o leite orgânico pode ser empregado como matéria-prima na fabricação de leites fermentados probióticos, agregando qualidade nutricional ao produto final. / The concern about sustainable technologies and demand for new functional foods arouses the interest for the development of new food products in addition to provide nutrition and health benefits to the consumer. Thus, this work aims to offer organic milk as a potential raw material for the manufacture of probiotic fermented milk. Therefore, studying the technological profile of strains of bifidobacteria in pure culture and in co-culture with Streptococcus thermophilus in organic and conventional milks, analyzing the chemical composition of milk; determining the profile of acidification of four strains of Bifidobacterium animalis subsp. lactis in pure culture and in co-culture with Streptococcus thermophilus; checking the counts of starter and probiotic cultures in fermented milks; examining the profile of fatty acids and conjugated linoleic acid content of fermented milks and the profile of texture of fermented milks. The highest rate of acidification profile was observed for the strains BL04 and B94 in organic milk and for the strain HN019 in both milks. The counts of all strains of B. animalis subsp. lactis were higher than 8.58 log10 colony forming units (CFU). mL-1. The organic milk had higher levels of iron and protein, whereas conventional milk had higher levels of fat and lactose. The main fatty acids were not influenced by the type of milk and higher amounts of conjugated linoleic acid (65% higher than the control) were found in organic fermented milk with the strain BB12 in co-culture with S. thermophilus. Thus, it was found that organic milk can be used as raw material in the manufacture of probiotic fermented milk, increasing nutritional quality to final product.
3

Perfil tecnológico de cepas de bifidobactéria em cultura pura e em co-cultura com Streptococcus thermophilus em leites orgânico e convencional / Technological profile of bifidobacteria strains in pure culture and in co-culture with Streptococcus thermophilus in organic and conventional milks

Florence, Ana Carolina Rodrigues 27 March 2009 (has links)
A crescente preocupação com tecnologias sustentáveis e a procura de novos alimentos funcionais despertam o interesse para o desenvolvimento de novos produtos alimentícios que proporcionem, além da nutrição, benefícios à saúde do consumidor. Assim, esse trabalho visa propor o leite orgânico como potencial matéria-prima para a fabricação de leites fermentados probióticos. Para tanto, estudou-se o perfil tecnológico de cepas de bifidobactéria em cultura pura e em co-cultura com Streptococcus thermophilus em leites orgânico e convencional, analisando a composição química dos leites, determinando o perfil de acidificação de quatro cepas de Bifidobacterium animalis subsp. lactis em cultura pura e em co-cultura com Streptococcus thermophilus, verificando a contagem microbiológica das culturas probióticas e iniciadoras nos leites fermentados, examinando o perfil de ácidos graxos e o teor de ácido linoléico conjugado dos leites fermentados e determinando o perfil de textura dos leites fermentados. A maior velocidade de acidificação foi observada para as cepas B94 e BL04 em leite orgânico e para a cepa HN019, para ambos os tipos de leite. As contagens de todas as cepas de B. animalis subsp. lactis foram superiores a 8,58 log10 unidades formadoras de colônia (UFC).mL-1</SUP. O leite orgânico apresentou maiores teores de ferro e proteína, enquanto o leite convencional apresentou maiores teores de gordura e lactose. Os principais ácidos graxos foram pouco influenciados pelo tipo de leite e as maiores quantidades de ácido linoléico conjugado (65 % maior do que o controle) foram encontradas em leite orgânico fermentado com a cepa BB12 em co-cultura com S. thermophilus. Assim, verificou-se que o leite orgânico pode ser empregado como matéria-prima na fabricação de leites fermentados probióticos, agregando qualidade nutricional ao produto final. / The concern about sustainable technologies and demand for new functional foods arouses the interest for the development of new food products in addition to provide nutrition and health benefits to the consumer. Thus, this work aims to offer organic milk as a potential raw material for the manufacture of probiotic fermented milk. Therefore, studying the technological profile of strains of bifidobacteria in pure culture and in co-culture with Streptococcus thermophilus in organic and conventional milks, analyzing the chemical composition of milk; determining the profile of acidification of four strains of Bifidobacterium animalis subsp. lactis in pure culture and in co-culture with Streptococcus thermophilus; checking the counts of starter and probiotic cultures in fermented milks; examining the profile of fatty acids and conjugated linoleic acid content of fermented milks and the profile of texture of fermented milks. The highest rate of acidification profile was observed for the strains BL04 and B94 in organic milk and for the strain HN019 in both milks. The counts of all strains of B. animalis subsp. lactis were higher than 8.58 log10 colony forming units (CFU). mL-1. The organic milk had higher levels of iron and protein, whereas conventional milk had higher levels of fat and lactose. The main fatty acids were not influenced by the type of milk and higher amounts of conjugated linoleic acid (65% higher than the control) were found in organic fermented milk with the strain BB12 in co-culture with S. thermophilus. Thus, it was found that organic milk can be used as raw material in the manufacture of probiotic fermented milk, increasing nutritional quality to final product.
4

MODELOS DE CLASSIFICAÇÃO DE SISTEMAS DE PRODUÇÃO DE LEITE EQUANTIFICAÇÃO DE ÁCIDOS GRAXOSPOR ESPECTROSCOPIA NIR / MILK PRODUCTION SYSTEMS CLASSIFICATION OF MODELS AND QUANTIFICATION OF FATTY ACIDS FOR NIR SPECTROSCOPY

Milani, Marceli Pazini 22 July 2016 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / It was evaluate the fatty acid profile of organic and conventional milk in differen seasons, the use of spectral data obtained in the near infrared region for classification of milk (organic vs conventional) and quantification of fatty acids. The tested rating models were: support vector machine (SVM) and independent flexible modeling by analogy class (SIMCA); and quantification: regression by partial least square (PLS) by interval (iPLS), principal component regression (PCR), regression by support vectors machine (SVR) and artificial neural networks (RNA). The milk samples used tanks producing units 135 and individual cows. The database used to develop the classification models were constructed from milk samples collected every two months, from July 2011 to May 2012, from 20 units producing organic milk and 20 conventional, located in the Southern of Brazil. The reference method the quantification of fatty acids used was gas chromatography (GC/FID). Spectral recordings were made in the range of 1100 to 2500nm in both samples of fresh milk as freeze-dried. The results did not show significant difference between the production system (organic and conventional) and the content of most fatty acids, including those identified as beneficial to consumer health. The use of near infrared spectroscopy associated with chemometric classification models made it possible to differentiate between milk samples from different systems, with an accuracy of 80,93% for freeze-dried samples and 59,32% for in natura samples by MVS method. Quantification of fatty acid in milk from NIR data is possible, and the selection of wavelengths by iPLS improved prediction model regarding the use of the entire spectrum. The artificial neural network has better performance than other models. The water content interfere with the performance of the models, both as to rate the samples to quantify fatty acids with significantly superior results with lyophilized samples. / Foi avaliado operfil de ácidos graxos do leite orgânico e convencional em diferentes estações do ano e, o uso de dados espectrais obtidos na região do infravermelho proximal para classificação do leite (orgânico vs convencional) e quantificação de ácidos graxos. Os modelos de classificação testados foram: máquina de vetores de suporte (SVM) e modelagem independente flexível por analogia de classe (SIMCA); e de quantificação: regressão por mínimos quadrados parciais (PLS) por intervalo (iPLS), regressão por componentes principais (PCR), regressão por máquina de vetores de suporte (SVR) e redes neurais artificiais (RNA). As amostras de leite utilizadas para desenvolver os modelos de quantificação totalizaram 421, sendo 286 oriundas de tanques de resfriamento de unidades produtoras e 135 individuais de vacas. O banco de dados utilizado para desenvolver os modelos de classificação foi construído a partir de amostras de leite coletadas a cada 2 meses, de julho de 2011 a maio de 2012, proveniente de 20 unidades produtora de leite orgânico e 20 convencionais, localizadas na região Sul do Brasil. Utilizou-se como método de referência para quantificação de ácidos graxosa cromatografia gasosa (GC/FID). Os registros espectrais foram realizados na faixa de 1100 a 2500nm tanto nas amostras de leite in natura como liofilizada. Os resultados não acusaram diferença significativa entre o sistema de produção (orgânico e convencional) quanto ao teor da maioria dos ácidos graxos, inclusive para os identificados como benéficos à saúde do consumidor. O uso da espectroscopia no infravermelho proximal associado a modelos quimiométricos de classificação possibilitou a diferenciação entre amostras de leite de diferentes sistemas, com acurácia de 80,93% para amostras liofilizadas e 59,32% para amostras in natura pelo método SVM. A quantificação de ácidos graxos no leite a partir de dados NIR é possível, sendo que a seleção de comprimentos de onda através do iPLS melhorou a predição do modelo em relação ao uso do espectro inteiro. A rede neural artificial apresentou desempenho superior aos demais modelos. O teor de água interfere no desempenho dos modelos, tanto para classificar as amostras como para quantificar ácidos graxos, com resultados significativamente superiores com amostras liofilizadas.
5

Environmental factors of attitude formation toward organic and conventional milk: A study of interpersonal networks and interactions of milk consumers in California

Wickstrom, Ashlan E. 01 September 2017 (has links)
No description available.
6

Réponses physiologiques de bifidobactéries soumises aux stress acide, froid et gastro-intestinal en laits biologique et conventionnel / Physiological responses of bifidobacteria subjected to acid, cold and gastro-intestinal stress in organic and conventional milks

Rodrigues Florence, Ana Carolina 20 March 2013 (has links)
Les bifidobactéries sont exposées à de nombreux stress, liés aux conditions environnementales rencontrées lors de la production, du stockage au froid, et pendant la digestion des laits fermentés. Afin d'améliorer leur survie, cette étude vise la compréhension des mécanismes de dégradation de l'état physiologique de différentes souches de Bifidobacterium soumises aux stress froid et acide et au stress gastro-intestinal simulé in vitro. Elle ambitionne également d'établir des relations entre la résistance aux différents stress et la teneur en acides gras membranaires et des laits biologiques et conventionnels. Les résultats montrent que l'activité acidifiante des bifidobactéries est souche-dépendante et qu'elle augmente lorsque les bactéries sont associées aux bactéries lactiques du yaourt, avec du lait biologique et lorsque la température d'incubation est fixée à 42°C au lieu de 37°C. La cultivabilité et la survie des souches ont été déterminées après fermentation, après stockage à 4°C pendant 7 à 28 jours, et pendant un processus de digestion simulé in-vitro dans un digesteur dynamique reproduisant le tractus gastro-intestinal. Ces caractéristiques sont améliorées dans les laits fermentés biologiques par rapport aux produits conventionnels, lorsque la fermentation est effectuée à 42°C jusqu'à pH 4,4, et lorsque les laits fermentés sont maintenus à 28°C pendant 12 heures avant d'être refroidi à 4°C. Ces procédures de fabrication spécifiques génèrent ainsi une adaptation physiologique des bifidobactéries aux stress. Pendant la digestion in-vitro, la cultivabilité des bifidobactéries se dégrade moins lorsque la fermentation se déroule en lait biologique plutôt qu'en lait conventionnel et, dans une moindre mesure, lorsque les procédures d'adaptation sont appliquées pendant la fabrication du lait fermenté. Ces résultats sont liés aux teneurs plus élevées en acides gras insaturés, en particulier en acides trans-vaccénique, linoléique conjugué et α-linolénique, qui caractérisent les produits biologiques. Ces profils d'acides gras particuliers aux laits biologiques permettent aux bifidobactéries de modifier leur composition en acides gras membranaires, en augmentant leur teneur en acides gras insaturés et en raccourcissant la longueur moyenne des chaînes d'acides gras saturés, adaptant ainsi leur fluidité membranaire. Lorsque les procédures de fabrication spécifiques sont mises en oeuvre pour induire une adaptation physiologique des bifidobactéries, la composition en acides gras des membranes se modifie différemment de ce qui est observé en lait biologique. Cette différence indique ainsi que d'autres mécanismes biologiques d'adaptation sont probablement impliqués, en particulier au niveau protéomique. Finalement, cette étude démontre que les modifications au niveau de la membrane contribuent à moduler la résistance aux stress technologique et gastro-intestinal de souches de Bifidobacterium. / Bifidobacteria are exposed to various stress, as a result of environmental conditions encountered during fermented milk production, cold storage and during digestion of the products inside gastrointestinal tract. In order to improve their survival, this study aimed at understanding the degradation mechanisms of the physiological state of various Bifidobacterium strains when exposed to cold, acid and in vitro simulated gastrointestinal stress. It also intended to establish relationships between stress resistance and milk and membrane fatty acids contents, in organic and conventional milks. The results showed that acidification activity of bifidobacteria was strain-dependent and increased when bifidobacteria were associated to yogurt cultures, when organic milk was used and when incubation temperature was set at 42°C instead of 37°C. Cultivability and survival of the Bifidobacterium strains were determined after fermentation, after storage at 4°C for 7 to 28 days, and during in-vitro digestion that was simulated in a dynamic gastrointestinal tract model. These characteristics were improved in organic fermented milks as compared to conventional products, when fermentation was performed at 42°C until pH 4.4, and when the fermented milks were kept at 28°C for 12 hours before being cooled to 4°C. These specific manufacture procedures thus generated physiological adaptation of the bifidobacteria to the stress. During in-vitro digestion, cultivability of bifidobacteria was less deteriorated when they were grown in organic instead of conventional milk, and to a less extent, when the adaptation procedures were applied during fermented milk manufacture. These results were related to the higher unsaturated fatty acids content, including trans-vaccenic, conjugated linoleic and α-linoleic acids that characterize organic products. These particular fatty acids profiles of organic milks allowed bifidobacteria to modify their membrane fatty acids composition, by increasing their unsaturated fatty acids contents and by shortening the length of medium chain saturated fatty acids, thus adapting their membrane fluidity. When specific manufacture procedures were carried out to trigger physiological adaptation of the bifidobacteria, membrane fatty acid composition changed différently from what is observed in organic milk. This difference indicates that other biological adaptation mechanisms are probably involved, especially at the proteomic level. Finally, this study demonstrated that modifications at membrane level contribute to modulate resistance against technology and gastro-intestinal stress of Bifidobacterium strains to better withstand technological and gastro-intestinal stress.
7

Ekologiško pieno gamyba ir perdirbimo perspektyvos Lietuvoje / Organic milk processing perspectives in Lithuania

Černiauskienė, Ilona 19 April 2007 (has links)
Aim: to carry out the research of the organic milk production conditions as well as the study of processing possibilities in Lithuania. The subject of research. The conditions of organic milk production as well as its relation to sanitary milk indicators in organic farms. Development of the production of organic milk and organic milk products in Lithuania and EC. Methodology. The research and assessment of microclimate was carried out during the winter period of 2005-2006. 14 organic farms from Jonava, Alytus, Raseiniai, Ukmergė and Molėtai districts were chosen for this purpose. The results of milk quality analysis from 27 organic and the same number from conventional dairy farms were selected from SE „Pieno tyrimai“. The research period was 01 10 2005 – 10 05 2006. During the period the qualitative parameters of organic and conventional milk, such as milk fat content and milk protein content, as well as sanitary parameters, such as general milk bacteria content (GBC) and somatic cells content (SCC), were observed and analyzed. The statistical analysis of the research results was carried out by the statistical package of the computer software “Graph Pad Prism” (Version 2.10; 1996) and software spreadsheet EXCEL. The software package Win Excel 97` was used for the visual presentation of the data. Results. The trend of organic dairy farms expansion has been observed. The owners of the organic farms pay too little attention to the wellbeing of the dairy cows. Because of... [to full text]
8

Essays on Environmentally Friendly Practices

Chang, Ching-Hsing 28 July 2011 (has links)
No description available.
9

Preisbildung und Preisreaktionen im Naturkosteinzelhandel - Eine Untersuchung an Biomilchprodukten anhand von Preiselastizitäten, Preisrigiditäten, Preissynchronisation und Preistransmission / Pricing and price behavior in organic retail - analyses of organic milk products by price elasticity, price rigidities, price synchronization and price transmission

Pfeuffer, Paul-Martin 25 May 2012 (has links)
No description available.
10

Aspectos físico-químicos e microbiológicos de leite orgânico e leite convencional

Jacinto, Lilian Mara Borges 23 November 2010 (has links)
The objective of this study was compare the physicochemical composition and microbiological quality of organic milk to conventional. It was collected 30 samples from 10 animals Gir (P.O.) and Girolando (1/4, ½ and 5/8), in differents months in lactation (between 2 and 5) in each of the properties during February, March and April. The Fazenda Felicidade used to produce organic milk and Fazenda Peroba, used to produce conventional milk, both are located in Ituiutaba, Minas Gerais. That samples were submitted to mesophilic count, determinacion of fat, protein and solids percentage, and were submitted too a somatic cell count. For the statistical analysis used the Student t test (p<0.05) between the means of each analysis. It concluded with this study, that organic milk had higher fat, solids and protein percentages, and no difference in mesophilic count and somatic cell count compared to the conventional milk. / Objetivou-se nesse trabalho a comparação físico-química e microbiológica do leite produzido organicamente em relação ao oriundo de produção convencional. Foram colhidas 30 amostras de 10 animais das raças gir (puras de origem) e girolando (nos graus de sangue: 1/4, 1/2 e 5/8), com períodos de lactação variados (entre o 2º e o 5º de lactação) em cada uma das duas propriedades, a Fazenda Felicidade, destinada à produção de leite orgânico e a Fazenda Peroba, destinada à produção de leite convencional situadas no município de Ituiutaba em Minas Gerais, no período dos meses de Fevereiro, Março e Abril. Estas foram submetidas à contagem de mesófilos, à determinação do teor de gordura, extrato seco e proteína e à contagem de células somáticas. Para a análise estatística, foi utilizado o teste t Student (p < 0,05) comparando as médias obtidas em cada uma das análises. Concluiu-se com tal estudo que o leite orgânico apresentou maiores teores de gordura, extrato seco e proteína, e não houve diferença na contagem de mesófilos e na contagem de células somáticas em relação ao leite convencional. / Mestre em Ciências Veterinárias

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