Os sucos e bebidas de frutas são altamente consumidos pela população brasileira, feitos de modo caseiro ou industrializados, porém pouco se sabe sobre o conteúdo de compostos bioativos e capacidade antioxidante destes diferentes tipos de produtos. O objetivo deste trabalho foi a determinação e comparação de diferentes compostos bioativos e da capacidade antioxidante de sucos naturais, integrais, néctares, preparados líquidos e sólidos para refresco nos sabores de tangerina, goiaba, maracujá, laranja e uva. Os sucos naturais foram preparados descartando as cascas e sementes e para cada tipo de bebida industrializada foram selecionadas três marcas distintas adquiridas no comércio local em Ribeirão Preto/SP. Foram determinados os teores dos seguintes compostos bioativos: fenólicos totais, flavonoides totais e amarelos, antocianinas totais, ácido ascórbico, licopeno e beta caroteno nas bebidas, assim como, a capacidade antioxidante foi determinada pelos métodos ABTS, DPPH e FRAP, sendo os dados analisados estatísticamente atráves da diferença entre as médias, também foram feitas correlações entre os diferentes métodos de capacidade antioxidante. Entre os achados observa-se que os preparados sólidos para refresco de diferentes marcas e sabores apresentaram os menores teores de compostos bioativos e capacidade antioxidante em relação às demais bebidas. O conteúdo de ácido ascórbico, fenólicos, flavonoides totais e amarelos apresentaram uma variabilidade grande entre as bebidas. As diferentes marcas de mesmo tipo de bebida e sabor apresentaram diferença significativa no teor de compostos bioativos e capacidade antioxidante. As antocianinas totais apresentaram-se em maior quantidade nos preparados líquidos e sucos integrais de uva. Os maiores teores de licopeno foram encontrados nos sucos natural e integrais de goiaba. O beta caroteno foi detectado apenas em algumas amostras sendo que as bebidas de tangerina apresentaram os maiores valores deste carotenoide, no suco natural, alguns sucos integrais, néctares e preparados líquidos para refresco. Os três diferentes métodos de capacidade antioxidante apresentaram resultados divergentes entre si e dados de correlação variáveis em sabores de frutas, porém, em todos os métodos, os preparados sólidos para refresco de diferentes marcas e sabores apresentaram medidas mais baixas ou nulas de capacidade antioxidante, mostrando que estes produtos são os mais inadequados do ponto de vista nutricional. Os resultados deste trabalho também mostram a dificuldade na caracterização destes produtos, comparando diferentes formulalções assim como diferentes produtos industrializados, mas apontam para valorização dos produtos naturais e menos processados / Juices and fruit drinks produced at home or industrialized are highly consumed by the Brazilian population, but the content of bioactive compounds and antioxidant capacity of these different types of products is unknown.The objective of this work was the determination and comparison of bioactive compounds and antioxidant capacity of natural and whole juices, nectars, liquid and solid prepared for soft drinks of tangerine, guava, passion fruit, orange and grape. The natural juices were prepared with the fruit pulp, scorning the barks and seeds and for each type of industrialized beverages, three different brands were collected in the local market of Ribeirão Preto -SP.Total phenolics, total and yellow flavonoids, total anthocyanins, ascorbic acid, lycopene and beta carotene were determined and analyzed by the difference between the averages, the antioxidant capacity was evaluated by ABTS, DPPH and FRAP assays, also their correlations were determined. Prepared solids for soft drinks of different brands and flavors had the lowest levels of bioactive compounds and antioxidant capacity compared to other beverages. The content of ascorbic acid, phenolics, total and yellow flavonoids presented a great variability between the drinks. The different brands of the same type of beverage and flavor presented significant difference in the content of bioactive compounds and antioxidant capacity.The total anthocyanins were higher in liquid prepared for soft drinks and whole grapes juices. The highest levels of lycopene were found in natural and whole juices of guava. Beta carotene was not found in all beverages studied, tangerine beverages presented the highest values of this carotenoid in natural juice, some whole juices, nectars and liquid prepared for soft drinks. Three different methods of antioxidant capacity presented divergent results and variable correlation data on fruit flavors, however, in all methods, solid prepared for soft drinks of different brands and flavors presented the smallest and zero antioxidant capacity, showing that these products are the least nutritionally suitable. The results of this work show the difficulty in characterizing these products, comparing different formulations as well as different industrialized products, but stand out for the valorization of natural and less processed products

The main aim of the present thesis was to compare different types of slaughter lines and their influence on the occurence of meat defects with emphasis on PSE defect. The research has been concentrated mainly on the slaughter lines which use the technology of stunning the animals with electricity and concentrated CO2. The research monitors the rate of PSE defect from the slaughter to the cutting of the pig (approximately 48 hours). For considering the difference in quality of the meat the basic identification indicators of both pH1 and the draining of meat were created. Furthermore, we monitored pH24 and pH48, too. Analyzing of the above mentioned indicators shows that stunning with concentrated CO2 is more suitable with regard to the quality of the meat. The average pH1 value was 0,3 (p < 0,001) higher, pH24 value was 0,243 (p < 0,001) higher and the average value of meat juice drainage was 2,16% lower (p < 0,001). The anylysis of the PSEi and PSE quality difference based on pH1 when stunning with the use of concentrated CO2 shows lower frequency of PSEi (7,843% lower) and PSE (1,961% lower). Based on meat juice drainage, PSEi frequency was 23,810% lower and PSE 4,762 % lower.

Made available in DSpace on 2014-06-11T19:24:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-11-27Bitstream added on 2014-06-13T20:32:09Z : No. of bitstreams: 1 astolfifilho_z_me_sjrp.pdf: 592649 bytes, checksum: 69d3ecc13d7c39bc240f4e0a6155b249 (MD5) / A encapsulação de sucos concentrados de limão e maracujá pelo processo de co-cristalização com sacarose foi avaliada pela determinação de propriedades físicas e fisico-químicas dos produtos obtidos. O processo de co-cristalização foi conduzido a partir da concentração de um xarope de sacarose até a supersaturação, quando então era adicionado o material a ser encapsulado. A partir daí, a mistura era submetida a uma intensa agitação que induzia à nucleação e à aglomeração do produto. O objetivo principal do trabalho foi avaliar o efeito da produção de suco adicionada e do pH do suco sobre a umidade, solubilidade, densidade aparente e ângulo de repouso dos produtos obtidos. Também foram estudados o comportamento higroscópico e a cinética de degradação de vitamina C do material encapsulado, em função das variáveis citadas acima. Finalmente, pelo uso da calorimetria diferencial de varredura, foram obtidas informações a respeito da influência da proporção de suco e do pH sobre as transições de fase observadas e sobre a microestrutura dos produtos co-cristalizados. Os produtos obtidos apresentaram menores umidades em menores proporções de sucos e pHs e as densidades resultaram na faixa em que se encontram a maioria dos pós alimentícios. O tempo de solubilização foi menor em maiores proporções de suco e baixos pHs. Os ângulos de repouso dos produtos foram satisfatórios se comparados com a faixa em que se encontram os pós da matriz encapsulante. Os materiais menos hidroscópicos foram os preparados com menor quantidade de suco e em menores pHs. A degradação de vitamina C durante a armazenagem foi menos acentuada em baixas proporções de suco e em menores pHs, tendo o suco de maracujá... / Encapsulation of concentrated lemon and passion fruit juices by co-crystallization with sucrose was studied by determining physical and physicochemical properties of the obtained products. The co-crystallization was carried out by concentrating a sucrose syrup until supersaturation and, then, adding the core material. The mixture was submitted to an intensive mixing, which induced nucleation and product agglomeration. The main objective of this work was to evaluate the effects of the added proportion of juice and juice pH on moisture, solubility, apparent density, and repose angle of co-crystallized products. The hygroscopic behavior and ascorbic acid degradation of the encapsulated material as affected by the above variables were also studied. The product microstructure was investigated by differential scanning calorimetry and polarized light microscopy. Lower moisture was obtained with lower juice proportions and lower pHþs, and apparent densities resulted in the range of the majority of food powders. Solubility increased with higher juice proportion and lower pHþs, whereas repose angles were similar to those of the encapsulating matrix. Less hygroscopic materials were obtained with lower juice proportion and lower pHþs. The passion fruit product presented lower rates of vitamin C degradation and degradation rates decreased with decreasing juice proportions and pHþs. The DSC thermograms and polarized light micrographs showed that the encapsulating matrix and the co-crystallized products were in the crystalline state.

Orientador: Maria Cecilia de Figueiredo Toledo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-08T23:41:04Z (GMT). No. of bitstreams: 1 Machado_RitaMargareteDonato_D.pdf: 591570 bytes, checksum: a0c994097a9f179aa01d119b5f2427b8 (MD5) Previous issue date: 2007 / Resumo: Embora os sulfitos sejam utilizados amplamente na indústria de alimentos, a ingestão desses aditivos têm sido associada a reações adversas em humanos, tais como broncoespasmos em indivíduos asmáticos sensíveis. Em avaliação da exposição aos sulfitos conduzida pelo Comitê Conjunto FAO/OMS de Peritos em Aditivos Alimentares (JECFA) durante sua 51º reunião em 1998, concluiu-se que o consumo de determinados alimentos e bebidas pode resultar em valores de ingestão de sulfitos acima da Ingestão Diária Aceitável (IDA) de 0,7 mg/kg peso corpóreo/dia, expressa como dióxido de enxofre (SO2). Com base nessas informações, o Comitê do Codex sobre Aditivos e Contaminantes de Alimentos (CCFAC) recomendou que a exposição diária a sulfitos a partir de todos os alimentos e bebidas fosse novamente avaliada pelo JECFA. O presente trabalho teve como objetivo a determinação analítica dos níveis de sulfito residual em vinhos e em sucos de frutas disponíveis comercialmente na região de Campinas, utilizando para isso o método oficial de Monier-Williams otimizado. Os níveis de sulfitos determinados foram comparados com valores máximos estabelecidos pela legislação brasileira e posteriormente utilizados para estimar a contribuição de vinhos e sucos de frutas como fonte de ingestão diária desses conservadores na dieta. Foram adquiridas 75 amostras de vinhos (66 de marcas nacionais e 9 de outros países da América do Sul), 15 de outras bebidas alcoólicas (sidras, fermentados de frutas, espumantes e filtrados de vinho), e 39 amostras de sucos de frutas nacionais entre concentrados (37) e prontos para o consumo (2). Em todas as amostras de vinhos e de outras bebidas alcoólicas analisadas (n=90) os níveis de sulfito, expressos como SO2, ficaram abaixo de 350 mg/L (limite máximo de uso estabelecido pela legislação brasileira), sendo que a maioria das amostras (90%) apresentou teores de sulfitos de até 150 mg/L. As amostras de sucos de frutas apresentaram concentrações de sulfitos abaixo de 50% do limite máximo permitido de 200 mg/L (333 mg/L para suco de caju). A exposição aos sulfitos pelo consumo de vinhos foi avaliada combinando níveis médios de sulfitos determinados analiticamente com estimativas de consumo hipotético em três cenários distintos (consumo diário de 150, 300 ou 450 mL). Os dados de ingestão indicaram que o consumo diário de 150 mL de vinho pode contribuir com mais de 50% da IDA desses aditivos, caso a concentração de sulfitos presente seja igual ou superior a 150 mg/L. A contribuição dos sucos de frutas para a ingestão de sulfitos foi avaliada utilizando-se dados de consumo de adolescentes brasileiros, entre 11 e 17 anos, obtidos por um questionário recordatório de 24 horas. A ingestão média de sulfitos a partir do consumo de sucos de frutas ficou bem abaixo da IDA estabelecida pelo JECFA. No entanto, estimativas a percentil 95 indicaram que o consumo de sucos de frutas contendo sulfitos em concentrações iguais ou superiores a 40 mg/L (como foi o caso dos sucos de acerola, goiaba, manga, abacaxi e tomate) pode resultar em valores de ingestões desses aditivos iguais ou acima da IDA. Embora os resultados obtidos nesse estudo indiquem que as concentrações de uso dos sulfitos pela indústria de vinhos e sucos de frutas estejam abaixo dos limites máximos estabelecidos pela legislação brasileira, a IDA desses aditivos pode ser excedida por indivíduos que consomem regularmente grandes quantidades desses produtos / Abstract: ANALYTICAL DETERMINATION OF SULPHITES IN WINES AND FRUIT JUICES AND ESTIMATION OF THEIR INTAKE. Although sulphites are used worldwide in the food industry, they have been implicated in causing adverse-type reactions in humans, such as asthmatic reactions (bronchospasms) in some subjects with asthma. Additionally, it was reported by the Joint Expert Committee on Food Additives (JECFA) at its fifty-first meeting that the consumption of certain foods and beverages may result in intakes of sulphites above the Acceptable Daily Intake (ADI) of 0.7 mg/kg body weight, driving the Codex Committee on Food Additives and Contaminants to recommend Member States to monitor sulphite intake in their countries. The present work aimed on determining the residual sulphite content in a variety of wines and sulphite-containing fruit juices commercially available in the region of Campinas-SP in order to check whether current uses of these preservatives are in accordance with the Brazilian legislation. These data were also used to estimate the contribution of wines and fruit juices to the intake of sulphites in Brazil. Seventy-five samples of wines (66 of national brands and 9 of brands from other South American countries), 15 samples of other alcoholic beverages (ciders, fruit-based beverages and sparkling wines), and 39 samples of national fruit juices, either concentrated (37) or ready-to-drink (2) were collected on the market, and analysed for sulphites using the optimized Monier-Williams distillation method. All samples of beverages presented residual sulphite levels, expressed as sulphur dioxide, below 350 mg/L (maximum permitted level established by the Brazilian legislation) with most samples (90%) containing residual sulphite up to 150 mg/L. The samples of fruit juices presented residual sulphite levels below 50% of the national maximum permitted level of 200 mg/L (333 mg/L for cashew apple juice). To estimate the contribution of wines to the intake of sulphites three hypothetical scenarios of wine daily consumption were assumed: 150, 300 and 450 mL. The data on intake indicated that the daily consumption of 150 mL of wine that contain sulphites at the level equal to or above 150 mg/L may contribute with more than 50% of the ADI of these additives. The contribution of fruit juices to the sulphite intake was assessed using consumption data from a group of 11-17 year-old Brazilian adolescents generated by a 24-hour dietary recall. The calculated sulphite intakes for average consumers of fruit juices were lower than the ADI set by the JECFA. However, estimates at the 95th percentile indicated that the consumption of juices containing sulphites at a concentration of 40 mg/L or above, what is the case of Antilles cherry, guava, mango, pineapple, and tomato juices, may lead to the intakes of these additives equal to or above the ADI. Despite the results have indicated that the actual use of sulphites by the industry in wines and fruit juices are well below those legally permitted by the Brazilian legislation, the ADI of sulphites may be exceeded by individuals whose dietary patterns lead to a high regular consumption of wines and sulphite-containing fruit juices / Doutorado / Ciência de Alimentos / Doutor em Ciência de Alimentos

Orientador: Jose de Assis Fonseca Faria / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-15T08:14:09Z (GMT). No. of bitstreams: 1 Walter_EduardoHenriqueMiranda_D.pdf: 5634901 bytes, checksum: 43f060f6a152462fae06f4a9bd631c70 (MD5) Previous issue date: 2010 / Resumo: Os sistemas assepticos sao uma das tecnologias mais empregadas na conservacao de bebidas a temperatura ambiente, compondo um mercado dinamico e promissor de produtos, embalagens e equipamentos. O objetivo desse trabalho foi avaliar um sistema asseptico projetado para produzir 1.000 L/h de leite longa vida e bebidas de alta acidez (dois tipos de chas e quatro refrescos mistos de maca, pera e pessego), com uma taxa de defeitos de 0,1%. As embalagens consistiram em bolsas flexiveis com termossoldagem tipo almofada de polietileno de baixa densidade pigmentado de branco com dioxido de titanio, tradicionalmente utilizado para leite pasteurizado, e laminado multicamada com propriedades de barreira ao oxigenio e a luz. Foram realizadas 15 producoes de leite longa vida e quatro das bebidas de alta acidez. Os testes foram conduzidos num sistema composto por equipamentos comerciais (tanques, bombas, valvulas, tubulacoes e trocador de calor) e em desenvolvimento (tanque de produto e maquina de embalagem tipo forma, enche e fecha), todos destinados as industrias de pequena escala de producao. O sistema foi avaliado com base em testes de esterilizacao comercial e analises de aceitacao sensorial dos produtos. A taxa de defeitos nas producoes de leite longa vida ficou na ordem de 2%, enquanto para as bebidas de alta acidez de 0,4%. A aceitacao sensorial do leite longa vida nas embalagens de polietileno, estocadas no escuro, variou entre quatro e sete semanas, de acordo com a qualidade da materia-prima, enquanto a aceitacao sensorial do produto exposto a luz foi de alguns dias. Na embalagem laminada, a luz nao afetou a estabilidade do produto, que teve uma vida de prateleira entre 12 e 24 semanas, dependendo da materia-prima. Esses resultados comprovaram a viabilidade das embalagens para a conservacao do produto. Entretanto, o sistema devera passar por melhorias, alcancando desse modo o potencial para aplicacao em industrias de pequena escala de producao. A simplicidade da linha de processamento e embalagem contribuiu para quebrar o paradigma de que os sistemas assepticos tem de ser sofisticados e onerosos / Abstract: Aseptic systems are one of the main technologies employed for shelf stable milk and juices, creating a dynamic and promising market for products, packaging and equipments. The aim of this study was to evaluate an aseptic system designed to produce 1000 L/h long-life milk and high acidity soft drinks (two teas and four soft drinks, mixed with apple, pear and peach), with a defect rate of 0.1 %. The packages were pillow-style pouches of low density polyethylene pigmented white with titanium dioxide, traditionally used for packaging pasteurized milk in Brazil, and multilayer laminate with oxygen and light barrier properties. There were performed 15 trials of long-life milk and four of soft drinks. Tests were conducted in the system composed of commercial equipment (tanks, pumps, valves, piping and heat exchanger), product tank, and form/fill/seal packaging machine, all used to small-scale production. The system evaluation was based on tests for commercial sterility and sensory acceptability testing of the products. The defect rate in the production of long-life milk was around 2%, while in high acidity drinks of 0.4%. The sensory acceptability of long-life milk in polyethylene containers, stored in the dark, ranged from four to seven weeks, according to the quality of raw material, while for the products exposed to light, it was of a few days. In the laminated bag, light did not affect the stability of the product, which had a shelf life ranged from 12 to 24 weeks, depending on the raw material used. These results have proved the feasibility of both packs for the conservation of the product. However, the system must go through improvements, thereby achieving the potential for application in small-scale industries. The simplicity of the processing and packaging system helped to break the paradigm that aseptic systems have to be sophisticated and expensive / Doutorado / Doutor em Tecnologia de Alimentos

La microfiltration est un procédé baro-membranaire largement utilisé pour stabiliser et clarifier les jus de fruits ou pour concentrer leur fraction pulpeuse. Toutefois le colmatage membranaire limite la productivité économique du procédé. Même si de nombreuses études ont été menées pour comprendre et limiter le colmatage, aucun véritable outil n'est aujourd'hui disponible pour prévoir la filtrabilité d'un jus de fruits. Le développement de ce type d'outils prévisionnels est pourtant essentiel pour faciliter l'optimisation des conditions de filtration et pour une meilleure maitrise du colmatage membranaire. Dans ce contexte, l'étude a été axée sur l'identification de nouveaux critères de filtrabilité des jus de fruits au travers de la compréhension et de la caractérisation des mécanismes de colmatage qui interviennent.En choisissant le jus d'orange comme modèle, une approche statistique a permis, dans un premier temps, une sélection rapide et pertinente des caractéristiques physico-chimiques des jus de fruits directement corrélées à leur filtrabilité, à savoir la matière sèche totale, l'extrait sec soluble, le pH, la conductivité et la granulométrie. Ensuite, des stratégies expérimentales complémentaires basées sur des filtrations à l'échelle du laboratoire ont été proposées pour identifier les différentes fractions colmatantes en fonction de leur taille ainsi que les mécanismes de colmatage associés. Ces stratégies novatrices ont permis d'étudier le pouvoir colmatant du jus d'orange en prenant en compte toute sa complexité et de proposer par la suite des cartographies de composés colmatants. Ces cartographies s'avèrent particulièrement intéressantes pour anticiper le comportement colmatant des jus de fruits sans avoir recours à des filtrations longues et coûteuses à grande échelle. Les résultats ont montré que le phénomène le plus important qui régit le colmatage membranaire global au cours de la filtration du jus d'orange semble être le colmatage externe par dépôt. Les objectifs de la dernière partie du travail, ont été de considérer plus fortement le caractère complexe et hétérogène des jus de fruits, pouvant les conduire à des changements brutaux de comportement lors de leur filtration. Pour cela des mesures rhéologiques en mode dynamique couplées à une stratégie d'isolement spécifique des différentes fractions colmatantes du jus d'orange ont été menées pour déterminer le comportement viscoélastique de la fraction insoluble du jus d'orange au cours de sa concentration. Les observations ont montré que les énergies des interactions entre les particules insolubles sont des fonctions croissantes de la concentration de la fraction insoluble et dépendent de la taille des particules. De plus, la transition vers un comportement « solide » du jus d'orange semble être favorisée par la présence des fractions particulaire et supra-colloïdale. Ces observations sont cohérentes avec le mécanisme de colmatage prédominant dû à l'accumulation de ces fractions à la surface de la membrane. La confrontation de nouvelles études de filtrabilité à l'échelle du laboratoire avec la performance de la filtration à grande échelle permettra de généraliser les stratégies proposées pour prédire la performance de la filtration de nouveaux jus de fruits. / Microfiltration is a pressure driven process successfully used to clarify and stabilize fruit juices or to concentrate their pulpy fraction. However, membrane fouling remains the critical factor governing the overall economic productivity of this process. Even if, many studies have been made to understand and limit membrane fouling, to date, there stills a lack of predicting tools to evaluate the filterability of fruit juices. However, it is interesting to develop practical and efficient tools for the prediction of fruit juices filterability in order to adapt and optimize filtration conditions to the fouling behavior of the filtered juice. In this respect, this study focused on the identification of new criteria of fruit juices filterability through the comprehension and the characterization of the potential fouling mechanisms.First, orange juice was chosen as test matrix and a statistical approach was used to select simple and relevant physico-chemical characteristics of this juice in relation with its filterability, namely dry matter, TSS, pH, conductivity, and particles size. Later, additional experimental strategies based on filtration tests at lab-scale were developed to identify the relevant size-classes of foulant compounds and related fouling mechanisms. These innovative strategies allowed studying the fouling potential of orange juice with the consideration of its complexity and proposing cartographies of foulant compounds. These cartographies are particularly interesting to anticipate the fouling behavior of fruit juices without any costly filtration operation at large scale. Moreover, results showed that external fouling seems to be the predominant fouling mechanism governing the overall membrane fouling during orange juice filtration. Finally, the aim of the last part of the work was to highlight the role of the complex and heterogeneous nature of fruit juices in their unexpected behavior during their filtration. For this purpose, the viscoelastic behavior of orange juice suspended solids during their concentration was obtained from rheological measurements in dynamic mode coupled with specific isolation of orange juice foulant fractions. Results showed that the energy of the interactions between juice particles increased as the suspended solids concentration increased and depends on the particles size. Furthermore, the solid-like behavior of the juice was enhanced by the presence of supra-colloids and large particles. These observations are in accordance with the predominant fouling mechanism that is due to the accumulation of these fruit fractions on the membrane surface. The confrontation of new filterability studies at laboratory scale with the performance of large-scale filtration will enable to generalize the proposed strategies to predict the performance of filtration of new fruit juices.

El presente trabajo trata sobre el «Estudio de prefactibilidad para la producción de una bebida natural a partir del tumbo andino (Passiflora mollissima) con linaza (Linum usitatissimum)». / Trabajo de investigación

Engineering : Chemical / M. Tech. (Chemical Engineering)

Thesis (PhD (Food Science))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Species of Alicyclobacillus are acid-tolerant and heat-resistant bacteria that cause spoilage of heat-treated fruit juices stored at room temperature. During the past decade, Alicyclobacillus spp. have become a major cause of spoilage in pasteurised fruit juices leading to significant economic losses world-wide. Spoilage has been reported in apple, pear, orange, peach, mango and white grape juice, as well as in fruit juice blends, fruit juice containing drinks and tomato products, such as tomato juice and canned tomatoes. Spoilage is characterised by a medicinal smell and guaiacol production. These endospore-formers have been shown to survive pasteurisation conditions of 95 °C for 2 min, grow at temperatures between 25° and 60 °C and a pH range of 2.5 to 6.0. Knowledge of this organism is limited, both locally and internationally and the route of contamination to the final product is not well established. In this study the fruit concentrate processing environment was investigated as a potential source and route of contamination for the final product. Species of Alicyclobacillus were isolated from orchard soil, various stages during processing and from fruit juice and concentrates. The isolates were identified based on morpholological, biochemical and physiological properties. Identification to species level was done by 16S ribosomal RNA gene sequencing and strain differentiation by RAPD-PCR. Results indicate that species of A. acidoterrestris and Alicyclobacillus acidocaldarius were found in orchard soil and throughout the processing environment. This is the first report on the isolation of these species from orchard soil, vinegar flies and the fruit processing environment. The 16 isolates identified as A. acidoterrestris grouped into four clusters based on RAPD-PCR banding patterns, suggesting that they belong to at least four genotypic groups. Isolates from the fruit concentrate, wash water and soil located outside of the fruit processing plant grouped into one cluster. Concluded from these results, A. acidoterrestris found in the wash water and soil outside of the factory could act as a potential reservoir of organisms for the contamination of the final fruit concentrate. Thus good manufacturing practices play an essential role in controlling incidence of spoilage caused by these bacteria. Fruit juices can be treated using ultraviolet (UV-C) light with a wavelength of 254 nm, which has a germicidal effect against micro-organisms. Alicyclobacillus acidoterrestris spores were inoculated into tap water, used wash water from a fruit processing plant and grape juice concentrate. Ultraviolet dosage levels (J L−1) of 0, 61, 122, 183, 244, 305 and 367 were applied using a novel UV-C turbulent flow system. The UV treatment method was shown to reliably achieve in excess of a 4 log10 reduction (99.99%) per 0.5 kJ L-1 of UV-C dosage in all the liquids inoculated with A. acidoterrestris. The applied novel UV technology could serve as an alternative to thermal treatments of fruit juices for the inactivation of Alicyclobacillus spores or in the treatment of contaminated processing wash water. Finally, the thermal inactivation at 95 °C for two strains of A. acidoterrestris isolated from contaminated fruit juice concentrates were investigated in a 0.1% (m/v) peptone buffer solution (pH 7.04) and grape juice (pH 4.02, 15.5 °Brix). The thermal inactivation of A. acidoterrestris spores followed first-order kinetics, suggesting that as the microbial population is exposed to a specific high temperature, the spores inactivated at a constant rate. D-values determined in the buffer solution were calculated to be 1.92 min and 2.29 min, while in grape juice D-values were found to be 2.25 min and 2.58 min for the two strains tested. From this study it is clear that the D-value is dependant on the strain tested, but also on the soluble solids of the solution the cells are suspended in. The results indicated that the spores of A. acidoterrestris isolated from South African fruit juice concentrate may survive after the pasteurisation treatment commonly applied during manufacturing. / AFRIKAANSE OPSOMMING: Spesies van Alicyclobacillus is suur-tolerante en hittebestande bakterieë wat bederf veroorsaak in hitte-behandelde vrugtesappe wat teen kamertemperatuur gestoor word. Gedurende die afgelope dekade het Alicyclobacillus spp. ‘n belangrike oorsaak van bederf in gepasteuriseerde vrugtesappe geword en beduidende ekonomiese verliese wêreldwyd veroorsaak. Bederf is aangeteken in appel-, peer-, lemoen-, perske-, mango- en witdruiwesap, sowel as in vrugtesapversnitte, vrugtesapbevattende drankies en in tamatieprodukte soos tamatiesap en ingemaakte tamaties. Bederf word gekenmerk deur ’n medisinale reuk en guaiacol produksie. Daar is gevind dat hierdie endospoorvormers pasteurisasie teen 95 °C vir 2 min kan oorleef en kan groei by temperature tussen 25° en 60 °C en ‘n pH van 2.5 to 6.0. Plaaslik sowel as internasionaal is kennis van hierdie organisme beperk en die roete van kontaminasie van produkte is nog nie goed vasgestel nie. In hierdie studie is die vrugtekonsentraat-verwerkingsmilieu ondersoek as ‘n moontlike bron en roete van kontaminasie van die finale produk. Spesies van Alicyclobacillus is vanuit vrugteboordgrond, verskeie verwerkingstadia en van vrugtesap en vrugtesapkonsentraat geïsoleer. Die isolate is op grond van morfologiese, biochemiese en fisiologiese eienskappe geïdentifiseer. Identifikasie tot spesiesvlak is deur 16S rDNS sekwensering gedoen en stam differensiasie deur RAPD-PKR. Resultate het aangetoon dat A. acidoterrestris en A. acidocaldarius in vrugteboordgrond sowel as in alle stadia van die verwerkingsmilieu voorkom. Dit is die eerste verslag van die isolering van hierdie spesies uit die Suid-Afrikaanse vrugteverwerkingsmilieu, vrugteboordgrond en asynvlieë. Die 16 isolate, geïdentifiseer as A. acidoterrestris en in vier groepe geplaas op grond van hul RAPD-PKR bandpatrone, dui aan dat hulle aan minstens vier genotipiese groepe behoort. Isolate afkomstig van die vrugtekonsentraat, waswater en die grond buitekant die vrugteverwerkingsaanleg het een groep gevorm. Uit hierdie resultate kan afgelei word dat A. acidoterrestris, wat in die waswater en grond buite die aanleg voorkom, as ‘n moontlike bron van organismes vir die kontaminering van die finale vrugtekonsentraat kan dien. Goeie vervaardigingspraktyke speel dus ‘n noodsaaklike rol in die beheer van bederf veroorsaak deur hierdie bakterieë. Vrugtesappe kan behandel word met ultravioletlig (UV-C) met ‘n golflengte van 254 nm wat ‘n dodende effek op mikro-organismes het. Kraanwater, gebruikte waswater van ‘n vrugtesapvervaardigingsaanleg en druiwesapkonsentraat is met A. acidoterrestris spore geïnokuleer. Ultraviolet toedieningsvlakke (J L−1) van 0, 61, 122, 183, 244, 305 en 367 is aangewend met behulp van ‘n nuwe UV-C drukvloei stelsel. Daar is aangetoon dat die UV-behandelingsmetode ‘n betroubare vermindering (99.99%) van meer as 4 log10 per 0.5 kJ L-1 van ‘n UV-C dosis gee in al die vloeistowwe wat geïnokuleer is met A. acidoterrestris. Die toegepaste nuwe UV-tegnologie kan gebruik word as ‘n alternatief tot die hittebehandeling van vrugtesap vir die deaktivering van Alicyclobacillus spore of in die behandeling van gekontamineerde waswater. Ten slotte is hitte-deaktivering teen 95 °C van twee stamme van A. acidoterrestris, geïsoleer uit gekontamineerde vrugtesapkonsentraat, in ‘n 0.1% (m/v) peptoonbufferoplossing (pH 7.04) en druiwesap (pH 4.02, 15.5 °Brix), ondersoek. Die hitte-deaktivering van A. acidoterrestris spore het eerste-orde kinetika gevolg, wat aandui dat die mikrobe-populasie teen ‘n konstante tempo afsterf, wanneer blootgestel aan ‘n spesifieke hoë temperatuur. Die D-waardes in die bufferoplossing is bereken as 1.92 min en 2.29 min, terwyl daar gevind is dat die D-waardes in druiwesap 2.25 min en 2.58 min is vir die twee betrokke stamme. Vanuit hierdie studie is dit duidelik dat die D-waardes afhang van die betrokke stam, maar ook van die oplosbare vaste stowwe van die oplossing waarin die selle opgelos is. Die resultate dui daarop dat die spore van A. acidoterrestris, wat geïsoleer is uit Suid-Afrikaanse vrugtesapkonsentraat, die pasteurisasiebehandeling wat algemeen tydens vervaardiging toegepas word, kan oorleef. Aangesien die toepassing van strenger hittebehandeling om spore van A. acidoterrestris te deaktiveer onaanvaarbare organoleptiese veranderinge in die produk tot gevolg het, word dit aanbeveel dat die risiko van bederf verminder behoort te word deur die gebruik van goeie vervaardigingspraktyke gedurende vrugteverwerking.

The electrochemical corrosion behavior of mild steel in apple, grape, mango, orange and the mixture of these juices was investigated in this study. Open circuit potential and weight loss analytical techniques were employed to establish the comparative corrosion rates of this material in the agro media over the interval of five days for a sixty-day immersion period at an ambient temperature. The chemical compositions of both mild steel and the agro media were determined to ascertain corrosion mechanism for the reaction. Polarization behavior of mild steel in the agro media were determined by Tafel extrapolation curves. The analysis showed that cathodic polarization curves were almost identical irrespective of the concentration of the various media while the anodic polarization curves exhibited varying active and passive corrosion behaviour due to passivating oxide films. The analysis of the results further showed that the corrosion rate of the metallic sample decreased with longer immersion periods which could be attributed to a gradual decline in acidity of these media as revealed by the pH results. Hence, the evolution of hydrogen gas and reduction of dissolved oxygen molecules from the reacting system were presumed to be major factors retarding corrosion of the solution involved. Similarly, the presence of suspended particles on the surface of the test steel sample could have also led to the impediment to corrosion rates from the surrounding atmosphere. Microscopic analysis of the corroded mild steel specimens revealed uniform and localized corrosion with Fe2O3 spotted as the main corrosion product. The result obtained from the electrochemical study showed that the corrosion rate of the mild steel sample was highest in the orange medium (1.53mm/yr), followed by grape medium (1.40mm/yr), mixture of these media (0.67mm/yr), mango medium (0.40mm/yr) while the metal corroded least in the apple medium (0.30mm/yr) over the duration of immersion. / Engineering : Chemical / M. Tech. (Chemical Engineering)