Thesis (Ph. D. in soil science)--Washington State University, May 2008. / Includes bibliographical references.

Ultrafiltration (UF), using Romicon pilot-scale hollow-fiber cartridges (Model HFXS-MK11) in the batch mode, was investigated as a possible procedure for clarifying, stabilizing and preserving White Riesling (WR) and Thompson Seedless (ThS) grape juice. The effect of UF processing of SO₂-treated or untreated juice, of process temperature and membrane molecular weight cut-off (MMWCO) on UF juice composition and quality, was determined. "Sparkling clear" pale light-colored UF permeates were obtained and subjected to storage stability trials at different temperatures. Juice parameters evaluated included proteins, phenolics, polyphenol oxidase (PPO), microorganisms, browning, haze and sensory properties. UF at elevated temperatures of up to 50°C, compared to lower temperatures, had the advantage of increased rate of filtration with decreases in browning or haze of clarified permeates and of markedly reduced microbial loads. UF of SO₂-treated juices (13- 20 ppm free) had several advantages including further reduction in browning, haze, and microbial load, and complete inhibition of PPO activity. More proteins (34% - 92%) than phenolics (2% - 27%) were retained by UF membranes. However, more proteins and less phenolics were retained in SO₂-treated than untreated juices. Increasing MMWCO from 10,000 to 100,000 had no effect on the retention of browning, haze, or microorganisms but decreased the retention of proteins from 58 percent to 34 percent in SO₂-treated WR juice. A MMWCO of 50,000 or less retained essentially all PPO. ThS juice browned more than WR during juice preparation and UF processing, yet its clarified permeates were lighter. It contained less phenolics, more proteins and more PPO activity, and higher percentages of its proteins and phenolics were retained by UF membranes. UF juices processed with or without low concentrations of SO₂ (13-20 ppm free) could be stored for at least one year at 1°C without fermentation spoilage. At 21°C only the treated juices could be stored for this long, untreated juices fermenting within one week. At 1°C, there was no increase in browning, but a gradual increase in haze upon storage, the latter being greater in untreated juices. At 21°C, browning increased gradually, resulting in pale golden juices but haze formation was markedly less than in juices stored at 1°C. Similar but accelerated changes occurred with storage at 38°C. The above changes correlated with the disappearance of free SO₂. Although juices were preserved for up to one year, "absolute juice sterility" was never obtained. Leakages around the cartridge gaskets, rather than failure of membranes, was believed to be responsible. Sensory analysis detected no significant differences (p = 0.05) in color, aroma and taste between juices processed with SO at 30°C and 50°C. Juices processed without SO₂ were not significantly different in color, but demonstrated small differences (p = 0.05) in aroma and taste. The SO₂-treated and untreated juices at both processing temperatures, as well as treated juices stored at 21°C and 1°C for twelve months, were significantly different (p = 0.01) in color, aroma and taste. Although these juices had different flavor "characters," only small or no significant differences (p = 0.05) in desirability were detected. It is concluded that good quality clarified grape juice but of different flavor "character" can be produced by UF, either in the presence or absence of SO₂. Both juice "styles" (± SO₂) may find preferred use, but juices processed with SO₂ have the advantage of ambient storage, retaining good quality after one year at 21°C. Recommended optimum processing conditions are 50°C, in the presence of minimal amounts of SO₂ (13-20 ppm free), using membrane molecular weight cut-off of 30-50,000. However, application of the process to "cold-sterilization" of grape juice requires further evaluation. / Graduation date: 1983

Thesis (M.S. in food science)--Washington State University, December 2008. / Title from PDF title page (viewed on July 10, 2009). "Department of Food Science." Includes bibliographical references (p. 84-94).

Orientador: Antonio Carlos de Oliveira Ferraz / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-21T13:30:46Z (GMT). No. of bitstreams: 1 Gomes_Daniel_D.pdf: 16813107 bytes, checksum: fa39cbbc8ab31a99a84b439cf1130d71 (MD5) Previous issue date: 2012 / Resumo: A cultivar de uva Niagara Rosada é a principal uva de mesa brasileira e o Estado de São Paulo é seu maior produtor com cerca de 2000 propriedades vitícolas (OLIVEIRA et al. 2008). O seu cultivo está se expandindo, dentre os fatores responsáveis destacam-se: o menor custo de produção em relação ao cultivo de uvas finas; maior rusticidade e menor necessidade de defensivos agrícolas. Apesar dos 79 anos de existência desde sua identificação e das inúmeras vantagens no cultivo, a uva 'Niagara Rosada' possui pouquíssimos estudos sobre sua pós-colheita, maturação ideal na vindima e suas consequências na vida útil dos frutos, e de sua aceitação pelo consumidor. A uva é comercializada freqüentemente abaixo do índice de maturação de 14o Brix indo contra a legislação brasileira. É comercializada imatura, ou seja, pouco doce, ácida e verde, causando malefícios a toda cadeia. Os produtores costumam comercializá-la mesmo fora da legislação vigente argumentando que não suportariam o manuseio, acondicionamento e transporte caso fossem colhidas no estádio recomendado. Diante do exposto o objetivo desse trabalho foi investigar a variação da qualidade e da vida útil da uva 'Niagara Rosada' quando colhida em diferentes estádios de maturação. Estabelecer faixas de maturação que proporcionem maior vida útil e aceitação dos consumidores e questionar a validade do parâmetro de colheita 14o Brix da legislação brasileira com outro parâmetro a razão sólidos solúveis / acidez titulável, que leva em conta a palatabilidade humana. Para tais avaliações a principio foi realizada uma coleta de cachos de uva cobrindo amplo espectro de estádios de maturações, observando a data da poda, os estádios fenológicos de 33 a 38 (EICHORN e LORENZ, 1984) e classificando-os cachos em faixas de maturação de sólidos solúveis de 1%, resultando em nove faixas de maturação de 8 a 17o Brix. Dentro deste amplo espectro de maturações os cachos foram analisadas utilizando-se a razão sólidos solúveis / acidez titulável, o que resultou na escolha três faixas de maturações 12, 14 e 16o Brix que posteriormente foram utilizadas para investigar a variação nos principais atributos qualitativos da uva 'Niagara Rosada' e em sua aceitação pelo consumidor. Para avaliação da qualidade e vida útil foi utilizado a, incidência de doenças, perda de massa, aparência do engaço, degrana, avaliação manual da rigidez dos cachos, vitamina C, taxa respiratória, firmeza e força de destacamento das bagas. Nas avaliações de aceitação e intenção de compra pelos consumidores incluíram-se também cachos na faixa de 10o Brix considerados imaturos neste trabalho, mas presentes na comercio, com intenção de avaliar a percepção do consumidor sobre esta faixa de maturação. A análise sensorial incluiu a faixa etária dos consumidores, aceitabilidade quanto à aparência, sabor, intensidade ideal do gosto doce e ácido e intenção de compra dos frutos nos diversos estádios de maturação. Não houve diferença nas faixas de maturação consideradas quanto aos indicadores temporais de qualidade, perda de massa, aparência do engaço, degrana, teor vitamina C e a taxa respiratória, porem influenciaram na incidência de doença e rigidez dos cachos, firmeza e força de destacamento das bagas. Durante o armazenamento todos os indicadores temporais de qualidade apresentaram variações, mas nem todos foram capazes de oferecer limites que pudessem ser utilizados como parâmetro de vida útil dos frutos. A vida útil foi avaliada sendo utilizada a perda de massa, aparência do engaço, degrana e rigidez do cacho; parâmetros que possibilitaram estabelecer limites claros de qualidade admissível a um cacho de uva e sua vida útil avaliada em 6,5, 6,75 e 8,5 dias para cachos com 16, 14 e 12o Brix. A cor da fruta foi seu principal atrativo aos consumidores, seguido de preço e tamanho do cacho. Em relação à aparência e a coloração dos cachos, os mais maduros foram os preferidos, porém, os consumidores não conseguiram discriminar ou simplesmente aceitaram a aparência e cor de cachos verdes com 10º Brix da mesma forma que os de 12º Brix, verificaram-se que a degrana de 5% é admitida pelos provados corroborando com determinações da Lei de padronização vigente, já a presença de bagas rompidas não foi admitida. Em relação ao sabor, cachos com 10º Brix (verdes) foram rejeitados quanto mais madura a uva, maior sua aceitação. A uva Niagara Rosada foi considerada pouco doce pelo consumidor e bem aceitas relação à acidez Quanto à avaliação de intenção de compra todas as maturações menos a de 10º Brix foram bem aceitas. Conclui-se que a uva 'Niagara Rosada' é adequada ao consumo nas faixas de 12, 14 e 16o Brix, contemplando a faixa de 12o Brix banida pela legislação brasileira. Conclui-se que acima de 16 Brix encontram-se em sobrematuração e impróprias para consumo 'in natura'. Conclui-se também que o parâmetro sólidos solúveis é inadequado para determinação da maturação. Uvas com 12o Brix obtiveram vida útil 22% maior que as faixas de 14 e 16o Brix que foram estatisticamente semelhantes. Conclui-se nas avaliações sensoriais que cachos na faixa dos 12 o Brix possuem poça rejeição pelo consumidor corroborando com as praticas comerciais correntes e que cachos com 14 e 16o Brix foram muito bem aceitos / Abstract: 'Niagara Rosada' is the main Brazilian table grape. The state of Sao Paulo is its largest producer with about 2000 vineyards (Oliveira et al. 2008). The cultivation of 'Niagara Rosada' is expanding because the low cost of production as compared to fine grapes, rusticity and less demands for agrochemicals. Despite 79 years of existence and those many cultivating advantages, 'Niagara Rosada' has very few post-harvest investigations in topics such as harvest time and its effect on shelf life, and consumer acceptance. The grape is often traded below the rate of maturation of the 14o Brix established by Brazilian legislation, and often, also sold immature, with little sugar content, high acidity, causing harm to all elements of the productivity chain. Producers are used to commercialize them even against legislation arguing the produce would not resist handling, packaging and transport if harvested in the recommended harvested stage. Given the above and to respond to qualitative variation of the main attributes of 'Niagara Rosada' in different degrees of maturation, this study aimed to investigate the variation in quality and service life of 'Niagara Rosada' when harvested in different stages f maturity. From these considerations the objectives of this work was to investigate the quality variation of 'Niagara Rosada' grapes harvested in different maturity, to establish the maturity stage with longer shelf life and consumer acceptance, and to contrast the current legislation that uses soluble solids to define a harvest stage against sugar acid rate, wich includes human perception. Initially, for those evaluations, clusters were harvested covering a wide maturity range, taking into consideration pruning date, phenological stage between 33 and 38, and classifying them according to soluble solids values ,within 1% variation, resulting in 9 maturity classes ranging from 8 to 17o Brix. Within this wide range, clusters were analyzed using sugar acid rate resulting in 3 maturation classes, 12, 14 and 16o Brix that further were used for quality and sensorial evaluation. Disease occurrence, mass loss, stem appearance, berry drop, cluster stiffness, vitamin C content, respiration rate, berry firmness and detachment force. For acceptance and consumer perception evaluation clusters having soluble solids values as low as 10o Brix were used. These analyses also included age group, appearance, flavor, acceptance, acidity and sugar taste intensity and buying intention of the 'Niagara Rosada' grape at different maturity stages. No difference was observed in the quality parameters such as mass loss, stem appearance, berry drop, vitamin C content and respiration rate among the considered maturity stages. However, maturity stages did influence disease occurrence, cluster stiffness, berry firmness and detachment force. During storage all temporal quality indicators showed variation, but not all of them could be used to determine shelf life. The ones used, then, were mass loss, stem appearance, berry drop and cluster stiffness that showed clear limits for admissible quality. Shelf life was identified as 6.5, 6.75, and 8.5 days corresponding to soluble solids values of 16, 14 and 12o Brix, respectively. Fruit color was the main acceptance criteria for consumers, followed by price and cluster size. As far as cluster appearance and color are concerned, the ripest ones were preferred. The sensorial panel was not able to differentiate maturity at 10 and 12o Brix maturity stages; berry drop up to 5% was accepted, supporting current legislation, but busted berries were not. Riper clusters were preferred. 'Niagara Rosada' was considered of little sugar content by the consumer and ideal concerning acidity. Buying intention included all maturity stages except the 10o Brix one. It was concluded that 'Niagara Rosada' grape is adequate for consumption when in the 12, 14 and 16o Brix maturity stages, which includes the 12o Brix stage, not accepted by current Brazilian legislation. It was concluded that above 16o Brix clusters are overripe and , therefore, not suitable for consumption. It was also concluded that soluble solids values are not suitable for maturity stage determination. Grapes with 12o B showed a 22 % greater shelf live than the other two considered maturity stages. Finally, it was concluded that 12o Brix cluster showed little rejection, supporting usual commercial practices. Clusters with 14 and 16o Brix were the most accepted / Doutorado / Tecnologia Pós-Colheita / Doutor em Engenharia Agrícola

Grape maturity is a critical attribute impacting potential wine quality. Maturity evaluation is difficult due to the many interrelated factors that impact physicochemical changes and limitations in the understanding of these factors. Current methods of assessing grape maturity are destructive, expensive, time consuming, subjective, and do not always strongly correlated to potential wine quality. This study evaluated the applicability of a conducting polymer-based electronic nose to monitor grape maturity by analyzing headspace volatiles. In the first part of the study, system and experimental parameters affecting the electronic nose operation were investigated to optimize detection of wine grape aroma. In the second part, the ability of an electronic nose to classify Cabernet Sauvignon (Vitis vinifera L.) grapes based on maturity was investigated. Maturity of samples collected at different weeks post-bloom was evaluated by measuring berry weight, pH, Brix, titratable acidity, total phenols, color intensity, hue, total anthocyanins, and total and phenol-free glycosides. Results were compared, using discriminant and canonical discriminant analysis, with analysis of headspace volatiles via the hand-held electronic nose. The electronic nose was able to determine the difference between the sample groups. Field measurements demonstrated the potential for the electronic nose as a rapid, non-destructive tool for evaluating grape maturity. / Master of Science

The feasibility of using hollow fiber ultrafi1tration for clarification, stabilization and preservation of white grape juice was evaluated. Flux and process parameters of a hollow fiber membrane ultrafi1tration unit (Romicon pilot scale, model FXS-MXII), were studied using white Riesling grape juice. Optimum processing conditions were determined for different nominal membrane molecular weight cut-off values. The effect of cut-off value changes on viscosity, pectin retention, pH, sugar content, titratable acidity, haze reduction and color were evaluated. Optimum conditions for processing were nominal membrane molecular weight cut-off = 50,000, temperature = 50°C, inlet pressure = 1.75 Kg/cm², outlet pressure = 1.40 Kg/cm², permeate flux = 72.57 L/M²-H. Concentration polarization and fouling of the membrane increased with feed juice viscosity and were limiting factors in permeation rate. A 93% retention of pectins was achieved and haze reduction was in the range of 91-93%. Sugar content, pH, titratable acidity, and color were not affected for any of the nominal membrane molecular weight cut-off values. / Graduation date: 1984

Thesis (M.S. in food science)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 4, 2010). "School of Food Science." Includes bibliographical references (p. 129-143).

No description available.

Thesis (M.S. in plant pathology)--Washington State University, May 2009. / Title from PDF title page (viewed on May 26, 2009). "Department of Plant Pathology." Includes bibliographical references (p. 35-38).

Promotionsarbeit--Eidgenössische Technische Hochschule, Zürich. / Vita. Bibliography: p. 73-79.