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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

Effects of Water Quality on Physico-chemical and Organoleptic Characteristics of selected Canned Fruits and Vegetables

Wilson, Anita Kay 01 May 1971 (has links)
The effect of processing water quality, specifically calcium and magnesium salt content (0-500 mg/1) and the addition of chelating agents (0- 250 mg/ 1 of aminopolycarboxylic acids, polyphosphates, hydroxycarboxylic acids or phytates), upon physico-chemical and organoleptic characteristics of canned Jonathan and Delicious apple slices, Montmorency cherries and Blue Lake green beans was investigated. Physical determinations: shear values, turbidity of syrup or brine measured via light transmittance, Hunter color and color difference meter readings and internal can corrosion; chemical composition: pectin as calcium pectate, volatile reducing substances, total acidity, pigment determinations, nitrate-nitrogen values; and sensory measurements: texture, shape, flavor, aroma, color value and uniformity of product and color value and turbidity of product brine or syrup were ascertained. Analyses of variance, Duncan's multiple mean comparison range tests and correlation or coefficients were calculated when appropriate. Use of hard water (300 mg/1) as a processing medium for canned apple slices and sour cherries decreased color and flavor acceptability but increased firmness and shear values. Excessive hardness toughened cherry epidermis making texture undesirable. Addition of 250 mg/1 CaNa2EDTA to Delicious apple slices canned in water containing 300 mg/1 salts improved color and flavor while firmness was retained. Delicious apple slices were firmer, and higher shear, nitrate-nitrogen and aroma scores and caused less detinning than Jonathan samples in all storage groups. As corrosion increased, nitrate-nitrogen, shear, firmness, flavor, aroma, and pigment values decreased. Color acceptability, reflectance, flavor and volatile reducing substance were higher and redness lower for Jonathan apple slices than Delicious samples stored at 35 and 75 F for 1 and 3 months, respectively, but not necessarily for samples stored at 100 F for 4 months. EDTA was ineffective in maintaining or improving Jonathan apple or Montmorency cherry quality, probably due ot the acidity of these cultivars. Apple and cherry quality decreased as storage temperature and duration increased from 35, 75 to 100 F for 1, 3 and 4 or 5 months, respectively, for all samples except Delicious apple slices with CaNa2EDTA. EDTA did provide most color protection in sour cherries, and citric acid, best flavor and aroma scores, while commercial and tap water processed sour cherries showed most deterioration, but none were of acceptable commercial quality after 5 month storage at 100 F. When comparing 1 month storage at 35 F with 3 months at 75 F, analyses of variance showed significant differences for every cherry characteristic measured except texture judged subjectively. All F values for apple storage variables were significant. Blue Lake green beans canned using distilled water or with 250 mg/ 1 CaNa2EDTA had higher color and greenness values, less turbidity, generally better flavor and aroma, but lower shear, shape and firmness scores than tap or hard water or commercially processed green beans. Addition of 250 mg/1 ascorbic acid to hard water used to process green beans retained greenness, clarity of brine, flavor and aroma while reducing slough and splitting of pods, when stored 4 months at 75 F.
2

Características sensoriais, físico-químicas e atividade biológica da própolis produzida no semiárido do estado do Rio Grande do Norte, Brasil / Sensory characteristics, physico-chemical and biological activity of propolis produced in the semiarid region of the state of Rio Grande do Norte, Brazil

Ferreira, Joselena Mendonça 27 February 2015 (has links)
Made available in DSpace on 2016-08-15T20:31:28Z (GMT). No. of bitstreams: 1 JoselenaMF_DISSERT.pdf: 1780661 bytes, checksum: 4b3479303097e19fd07024f10fea488f (MD5) Previous issue date: 2015-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Surveys of propolis have shown how this product has the potential for various therapeutic purposes. However, it has been found that this resin has a variability of compounds and biological activities depending on their place of origin, due to differences in vegetation from one location to another. The objective of this study was to verify the organoleptic, physico-chemical, and antimicrobial and antioxidant activity of propolis produced in different cities in the state of Rio Grande do Norte (Mossoró, Areia Branca, Alto do Rodrigues, Afonso Bezerra and Cerro Cora). Was identified the months of highest production in the apiaries of Mossoró and Alto do Rodrigues and variations in their properties to be assessed in two different periods of the year (post- rainy and dry). The propolis samples were collected in the five apiaries, each with 9 beehives of Langstroth type containing colonies of Apis mellifera bees. The method of production occurred after the introduction of a wooden bar with dimensions of 370 x 20 x 20 mm in the front and one at the rear, between the nest and the supers, creating a space of approximately 20 mm on each side where propolis produced was collected. After harvesting, the propolis samples were weighed, evaluated when the organoleptic characteristics (color and consistency) and stored in a freezer. For extraction in ethanol, were made set of propolis samples collected from colonies per apiary, 4 for sample Mossoró, 2 of Alto do Rodrigues, one of Areia Branca and 1 Afonso Bezerra and 1 Cerro Cora, totaling 9 sets sample. Thereupon, ethanolic extracts were made to quantify these phenols, flavonoids, total waxes, antimicrobial and antioxidant activities. For the antioxidant, free radical DPPH tests were performed and β-carotene system / linoleic acid. In the evaluation of the antimicrobial activity, the extracts were tested on the bacteria Staphylococcus aureus and Escherichia coli. Propolis of the county Alto do Rodrigues had the highest means of production compared to the apiary in Mossoró. The extracts showed significant results in all tests, with makeup and diverse biological activity. Seven of the nine samples analyzed possessed levels of waxes according to the required by law. There was a significant correlation between the levels of waxes and total phenolic content (R2> 0.5). Samples of propolis Afonso Bezerra and Mossoro had higher levels of flavonoids commonly found in the Brazilian propolis samples. The High extracts of Rodrigues, Afonso Bezerra and Mossoro were more promising in physical chemistry evaluation and antioxidant and antimicrobial activity. The antioxidant activity of the sample Alto do Rodrigues (52%) along with the sample Areia Branca (75%) had the highest percentage by methods DPPH system and β-carotene / Linoleic acid, respectively. The antimicrobial activity tests to S. aureus and E. coli, samples of Alto do Rodrigues and Afonso Bezerra performed better in antimicrobial activity, for having formed halos of inhibition at all concentrations tested in both the strains. In general, the samples had diverse biological activity and physical-chemical profile / As pesquisas com a própolis têm demonstrado o quanto esse produto tem potencial para diversos fins terapêuticos. No entanto, já foi verificado que essa resina possui uma variabilidade de compostos e atividades biológicas dependendo do seu local de origem, devido a diferenças nas vegetações de um local para outro. O objetivo deste estudo foi verificar as características organolépticas, físico-químicas, e as atividades antimicrobiana e antioxidante da própolis produzida em diferentes cidades do estado do Rio Grande do Norte (Mossoró, Areia Branca, Alto do Rodrigues, Afonso Bezerra e Cerro Corá). Foi identificado os meses de maior produção nos apiários de Mossoró e Alto do Rodrigues e as variações em suas propriedades ao serem avaliadas em dois períodos distintos do ano (pós-chuvoso e seco). As amostras de própolis foram coletadas nos cinco apiários, cada um com 9 colmeias do tipo Langstroth contendo colônias de abelhas Apis mellifera. O método de produção ocorreu a partir da introdução de uma barra de madeira com dimensões de 370 mm x 20 mm x 20 mm na parte frontal e outra na traseira, entre o ninho e a melgueira, criando um espaço de aproximadamente 20 mm nas duas laterais, onde a própolis produzida foi coletada. Após as coletas, as amostras de própolis foram pesadas, avaliadas quando as características organolépticas (cor e consistência) e armazenadas em freezer. Para a extração em etanol, foram feitos conjunto de amostras das própolis coletadas das colônias por apiário, sendo 4 para amostras de Mossoró, 2 de Alto do Rodrigues, 1 de Areia Branca e 1 de Afonso Bezerra e 1 de Cerro Corá, totalizando 9 conjuntos amostrais. Logo após, foram feitos extratos etanólicos destes para quantificação de fenóis, flavonóides, ceras totais, atividades antimicrobiana e antioxidante. Para a atividade antioxidante, foram realizados os testes do radical livre DPPH e o sistema β-caroteno/ácido linoleico. Na avaliação da atividade antimicrobiana, os extratos foram testados frente às bactérias Staphylococcus aureus e Escherichia coli. A própolis do município de Alto do Rodrigues obteve maiores médias de produção quando comparada a do apiário em Mossoró. Os extratos apresentaram resultados significativos em todos os testes, com composição e atividade biológica diversificada. Sete das nove amostras avaliadas possuíram teores de ceras de acordo com o exigido pela legislação. Houve correlação significativa entre os níveis de ceras e os teores de fenóis totais (R2 > 0,5). As amostras de própolis de Afonso Bezerra e Mossoró apresentaram níveis de flavonóides superior aos comumente encontrados em amostras de própolis brasileiras. Os extratos de Alto do Rodrigues, Afonso Bezerra e Mossoró foram mais promissores na avaliação físico-química e atividade antioxidante e antimicrobiana. Na atividade antioxidante, a amostra de Alto do Rodrigues (52%), juntamente com a amostra de Areia Branca (75%) obtiveram os melhores percentuais pelos métodos do DPPH e sistema β-caroteno/ácido linoleico, respectivamente. Nos testes de atividade antimicrobiana frente à S. aureus e E.coli, as amostras de Alto do Rodrigues e Afonso Bezerra tiveram um melhor desempenho na atividade antimicrobiana, por terem formado halos de inibição em todas as concentrações testadas em ambas às cepas. Em geral, as amostras apresentaram atividade biológica e perfil físico-químico diversificado

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