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Thesis (M.A.)--Ohio University, March, 2006. / Title from PDF t.p. Includes bibliographical references (p. 78-86)

Consumer's demand for more natural and high quality food products products, presenting health benefits, has increased over the years. Besides the nutritional aspects, an appealing appearance and texture is also required. Cloudiness or opacity (cloudy appearance) is an important citrus drinks property (orange, lime, lemon, etc.), since it gives natural fruit juice appeal. This property can be achieved through addition of clouding agents, which also help in uniform distribution of flavors throughout the liquid beverage. A common problem in the beverage industry is producing cloud or flavor emulsions that remain stable over the desired shelf life. Beverage cloud emulsions are oil-in-water emulsions to provide cloudiness and are prepared in a concentrated form, but diluted prior to the consumption. / Optical and rheological properties of beverage cloud emulsions as a function of water-phase and oil-phase concentrations were investigated. The specific gravity of phases, particle size distribution and creaming stability of prepared emulsions in diluted forms were evaluated. The rate of cloud emulsion creaming by determining the rheology of water phase, difference in specific gravities of the phases and droplet properties of the emulsion in presence and absence of weighting agents (sucrose acetate isobutyrate and brominated vegetable oil) or/and xanthan gum was studied. Flow and dynamic rheological properties of single-phases and emulsions containing modified starch and arabic gum as surface active hydrocolloids as well as xanthan and tragacanth as stabilizers gums were investigated. Finally, stability of cloud emulsions in orange juice drink was examined. / Oil-phase concentration had a significant effect (P < 0.05) on increasing the opacity of emulsion. Raise in viscosity of emulsions was more pronounced as oil concentration increased and shear thinning behavior of oil added emulsions was associated with droplet flocculation. Creaming in acidified sugar solution of 11°Bx and pH 3 was observed when the oil-phase specific gravity decreased and sedimentation occurred at the lower viscosity of water phase. Addition of xanthan gum into the water phase decreased the flow behavior index (n) form 0.88 down to 0.31 and increased elastic modulus (G') over 20 times at elevated frequency (o = 50 rad/s) and perk up the stability of the emulsion. / The xanthan gum added emulsion indicated smaller average particle size and demonstrated 14 and 5 times slower separation compared to the emulsions without or with the addition of weighting agents respectively. Starch-xanthan stabilized emulsion and associated water phase at 1.5:1 surface active gum to oil ratio demonstrated viscoelastic behavior (G' ≥ G") with lower droplets coalescence and creaming rates, 0.013 nm/day and 0.02 percent backscattering/day respectively. Conversely, arabic-xanthan stabilized emulsion at 1:1 gum to oil ratio showed the highest rate of droplets coalescence at 0.057 rim/day and greater degree of creaming at 0.61 percent transmission/day. While creaming were associated with arabic gum stabilized emulsions, after 3 month storage, modified starch illustrated appropriate shelf stability with no sign of creaming in orange juice drink.

Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 162-164).

High pressure (HP) processing has been emerging rapidly as a novel technique for non-thermal preservation of foods. Application of HP processing for shelf life extension of orange juice was the principal objective of the current research. To accomplish this objective, and to establish a scientific basis for HP processing of orange juice, a systemic approach was used which included the evaluation of: (a) HP inactivation kinetics of pectin methyl esterase (PME, the key enzyme in orange juice implicated with respect to quality changes), (b) destruction of spoilage microorganisms and changes in product quality, (c) HP process verification and finally, (d) storage studies on HP treated orange juice. / In preliminary studies, the effect of HP treatment on indigenous microorganisms, texture and color of selected fresh fruits and vegetables were evaluated. Results showed that HP had a significant effect on the destruction of microorganisms. Product texture and color were mildly affected, often resembling the appearance of mildly heat-treated products. / Pressure induced inactivation kinetics of pectin methyl esterase (PME) was investigated at pH 3.7 and 3.2 in freshly squeezed single strength (12.6°Brix) and concentrated (10--40° Brix) orange juice. Results showed a biphasic nature of pressure induced inactivation of PME in both juices. The first phase consisted of rapid change in inactivation of enzyme, designated as instantaneous pressure kill (IPK), due to pulse pressurization, followed by gradual inactivation of enzyme, characterized by a first order rate of inactivation during pressure hold-time. / Combination treatment involving pressure cycle, pressure level and pressure hold-time was then evaluated for inactivation of PME using a response surface methodology. Overall, pressure pulse had a lower effect on inactivation of PME compared to other factors. / Pressure destruction kinetics of Leuconostoc mesenteroides and Saccharomyces cerevisiae the spoilage organisms in orange juice, were then investigated. Pressure destruction kinetics followed the same dual effect behavior, as observed with PME inactivation. IPK effect increased with pressure cycles and was more pronounced with S. cerevisiae that Leu. mesenteroides. / Storage studies of HP treated single strength and concentrated orange juice were conducted at selected temperatures (4, 10 and 20°C). Results showed that treated juice was microbiologically stable from a few days to several weeks depending on type of juice, storage temperature and processing conditions. (Abstract shortened by UMI.)

The effect of refluxing on the aromas of Valencia aqueous orange essences was determined through analysis by GC, MS, Osme, and by a descriptive panel. The strengths and descriptions of volatiles were investigated to determine if differences in essence aroma character and intensity existed. During production, 1 sample was subjected to reflux conditions and contained 16.2% ethanol. The other sample had not been refluxed and contained 6% ethanol. The aroma activity of volatiles was measured by Osme, a method of gas chromatography / olfactometry developed at Oregon State University. The majority of aroma active peaks were found to be present in the reflux and no reflux aqueous orange essence samples. Octanal, linalool, ethyl butanoate and 2 unknowns were the components with strongest aroma activities in both samples. Descriptive analysis was conducted with 7 trained panelists from the Food Science and Technology Department at Oregon State University. Following 12 training sessions, initial testing indicated overall intensity was the major separating attribute of essences. After 6 additional training sessions and adjustment of concentrations to yield essences of approximate equal strength, testing indicated there were no significant differences between samples. Osmegrams, GC FID chromatograms, and descriptive analysis indicated the effect of reflux produced an essence that was more concentrated. Although refluxing concentrated individual volatiles to different levels, character differences other than those associated with concentration were minimal. / Graduation date: 1996

Note:

Unpasteurized (condition A) and pasteurized (condition B) orange juice samples were stored frozen for eight months. In addition, pasteurized samples were also aseptically packaged and stored at +1°C in polyethylene bags (condition C). Nine quality parameters were monitored during the eight months of storage: sedimentation of the pulp, cloud measurement, aroma volatiles, ascorbic acid concentration, viscosity, density, colour, sugar content (sucrose, glucose and fructose), organic acids (malic and citric), in addition to sensory analysis. The optimum storage condition for freshly processed orange juice was the unpasteurized frozen storage method (condition A). The juice retained most of its chemical and physical properties and was rated by a sensory panel to have the highest sensory score.

Resumo: Este trabalho teve como objetivo avaliar o néctar e o suco de laranja pronto para beber e sua rotulagem, com base na legislação vigente e na interpretação do consumidor. Foi realizada uma avaliação crítica da legislação brasileira de sucos, com ênfase no suco de fruta pronto para beber, visando compreender suas exigências com relação ao suco de laranja e à rotulagem. A adequação dos rótulos das principais marcas de néctar e de suco de laranja pronto para beber disponíveis em supermercados à legislação vigente foi avaliada, assim como suas características físico-químicas. O uso e a interpretação das informações constantes nos rótulos pelos consumidores e sua influência na decisão de compra foram avaliados por meio de entrevista em supermercados. A influência das informações do rótulo sobre a intenção de compra do consumidor foi estudada usando a análise conjunta de fatores. De acordo com os resultados foi verificado que existem lacunas na legislação brasileira de sucos que favorecem a interpretação equivocada e a presença de sucos não regulamentados no mercado, e que mudanças freqüentes e diferentes informações em legislações de rotulagem concomitantemente vigentes também podem levar à interpretação equivocada pelo consumidor. Verificou-se que as datas de fabricação e de validade foram as informações do rótulo mais consultadas pelos entrevistados e os fatores mais importantes para a decisão de compra do produto foram marca, preço e sabor. As expressões néctar, suco integral e natural ou 100% natural foram interpretadas de maneira positiva pelos consumidores, enquanto a expressão suco reconstituído foi interpretada negativamente. Os rótulos das marcas de néctar e suco de laranja pronto para beber analisadas atenderam à legislação de sucos e bebidas, à legislação... (Resumo completo, clicara cesso eletrônico abaixo) / Abstract: The aim of this work was to evaluate the ready to drink nectar and orange juice and the label, with basis of Brazilian labeling regulations and the consumer interpretation. A critical evaluation of fruit juice Brazilian regulations, with emphasis on ready to drink fruit juice, was carried out to understand the requirements related to orange juice and labeling. The suitability of labels from the main brands of commercially available ready to drink orange juice to the Brazilian regulations was evaluated, as well as the physicochemical characteristics. The consumer interpretation and use for labeling information and their influence on the decision of purchase were evaluated by interviews at supermarkets. The influence of labeling information on the purchase intention of the consumers, using conjoint analysis was also studied. The results showed that there are some gaps in fruit juice Brazilian regulations that allow mistaken understanding and inclusion of not regulated juices in the market, and that frequent changes and different information in the Brazilian labeling regulations in force at the same time also can take to mistaken understanding. The interpretation of the consumers pointed out that date of manufacture and shelf life were the most important information on the label and brand, price and flavor were the most important factors for purchasing. The interpretation of the consumers of ready to drink orange juice about the expressions nectar, whole and natural juice or 100% natural was positive, while that from the expression reconstituted juice was negative. Labels from all the brands of ready to drink nectar and orange juice were in accordance with the fruit juice and beverage Brazilian regulations, the food packaged labeling Brazilian regulations, the complementary nutritional information regulations and the presence or absence... (Complete abstract click electronic access below) / Orientador: Magali Monteiro da Silva / Coorientador: Karina Olbrich dos Santos / Banca: Valéria Paula Rodrigues Minim / Banca: Natalia Soares Janzantti / Mestre

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