Contribuição para o estudo da produção de azeitona de mesa da cultivar Cobrançosa: caracterização físico-química, organolética e nutricional

Dissertação de Mestrado, Tecnologia dos Alimentos, Instituto Superior de Engenharia, Universidade do Algarve, 2016

Contribuição para o estudo de produção de azeitona de mesa da cultivar Cobrançosa: caraterização microbiológica

Dissertação de Mestrado, Tecnologia dos Alimentos, Instituto Superior de Engenharia, Universidade do Algarve, 2016

Azeitona de mesa natural da cultivar Maçanilha com baixo teor de cloreto de sódio

Dissertação de mestrado, Tecnologia dos Alimentos, Instituto Superior de Engenharia, Universidade do Algarve, 2014

Avaliação do potencial probiótico de leveduras isoladas de azeitonas de mesa da cultivar Negrinha de Freixo

Probióticos são definidos como microrganismos vivos, que quando administrados em quantidades adequadas, conferem benefícios à saúde do hospedeiro. Atualmente a pesquisa de microrganismos probióticos a partir da fermentação da azeitona tem-se centrado nas bactérias ácido-lácticas, sendo escassos os estudos envolvendo leveduras. No presente trabalho avaliou-se o potencial probiótico de estirpes de leveduras previamente isoladas durante o processo de fermentação natural de azeitona de mesada cultivar Negrinha de Freixo. Foram avaliadas 16 estirpes em relação à atividade enzimática (catalase, amilase, xilanase, protease e β-glucosidase); ao crescimento a 37ºC; ação inibitória frente a microrganismos patogénicos; capacidade de autoagregação; atividade antioxidante (utilizando o método de DPPH); e resistência ao aparelho digestivo humano, a partir de uma simulação in vitro da digestão gástrica e pancreática. Os resultados apresentados para a atividade enzimática indicaram que em alguns isolados foi detetado fraca atividade das enzimas protease, xilanase e amilase. Já uma atividade forte de lipase foi observada nas estirpes Pichia manshurica e Saccharomyces cerevisiae (15A e 15B). Para a enzima β-glucosidase, identificou-se atividade forte em Rhodotorula graminis, Rhodotorula glutinis, Candida norvegica, Pichia guilliermondii e Galactomyces reessii. Relativamente à capacidade de crescimento à temperatura corporal (37ºC), três estirpes (Saccharomyces cerevisiae 15B; Candida tropicalis 1A; e Pichia membranifaciens 29A) destacaram-se por apresentar maior taxa específica de crescimento. A capacidade bloqueadora dos radicais livres DPPH foi verificada em 10 estirpes, sendo as estirpes de S. cerevisiae as que mais se destacaram dentre as outras. As estirpes C. norvegica e G. reessii (34A) apresentaram capacidade antifúngica frente ao microrganismo patogénico Cryptococcus neoformans. Em relação à capacidade de autoagregação avaliada, as estirpes S. cerevisiae (15A), Candida tropicalis (1A) e C. norvegica (7A) apresentaram ao fim de 24 horas percentagens superiores a 80%. Relativamenteà resistência frente às condições presentes no trato gastrointestinal in vitro, a estirpe P. guilliermondii (25A), destacou-se dentre as demais, por apresentar maior capacidade de sobrevivência em todo o processo digestivo simulado. As estirpes Candida boidinii (37A) e S. cerevisiae (15A) apresentaram menor capacidade de sobrevivência nestas condições. Contudo, serão necessários testes adicionais para complementar estes resultados.

Quantificação do teor em metais em azeites e azeitonas da cv Cobrançosa

A olivicultura possui uma grande importância no cenário económico mundial, devido ao facto de a azeitona e o azeite fazerem parte da dieta alimentar de muitos países, especificamente os da região Mediterrânea. A “Cobrançosa” é uma cultivar Portuguesa com muita importância na região de Trás-os-Montes encontrando-se atualmente disseminada por seis regiões de Denominação de Origem Protegida. Os contaminantes emitidos para a atmosfera atingem as oliveiras e as azeitonas através da água, do ar, das plantas e do solo. Embora a ingestão de metais pesados através da azeitona e do azeite seja reduzida, a sua bioacumulação no organismo pode resultar em toxicidade e pôr em causa a saúde pública. É deste ponto de vista, que se centra o objetivo geral deste trabalho. Assim sendo, tentou-se quantificar o conteúdo de metais (de segurança e de qualidade), tais como o alumínio, arsénio, cádmio, chumbo, cálcio, cobalto, cobre, ferro, magnésio, manganês, sódio, níquel, e zinco nas azeitonas e azeites da cv “Cobrançosa” de seis clones em dois estados de maturação, com diferentes rendimentos de produção e diferentes atividades antioxidantes. Verificou-se que todos os metais analisados se encontram de acordo com o legislado e publicado por outros autores, verificando-se neste estudo particular que a componente genética que diferencia as amostras em estudo, não está significativamente relacionada com o conteúdo em metais.

Inheritance of Resistance to Rice Tungro Spherical Virus in a Near-Isogenic Line Derived from Utri Merah and in Rice Cultivar TKM6

Resistance to rice virus diseases is an important requirement in many Southeast Asian rice breeding programs. Inheritance of resistance to rice tungro spherical virus (RTSV) in TW5, a near-isogenic line derived from Indonesian rice cultivar Utri Merah, was compared to that in TKM6, an Indian rice cultivar. Both TKM6 and Utri Merah are cultivars resistant to RTSV infections. Crosses were made between TKM6 and TN1, a susceptible cultivar, and between TW5 and TN1, and F3 lines were evaluated for their resistance to RTSV using two RTSV inoculum sources and a serological assay (ELISA). In TKM6, the resistance to the mixture of RTSV-V + RTBV inoculum source was controlled by a single recessive gene, whereas in TW5, the resistance was controlled by two recessive genes. A single recessive gene, however, controlled the resistance in TW5 when another RTSV variant, RTSV-VI, was used, suggesting that the resistance in TW5 depends on the nature of the RTSV inoculum used. RT-PCR, sequence, and phylogenetic analyses confirmed that RTSV-VI inoculum differs from RTSV-V inoculum and accurate phenotyping of the resistance to RTSV requires the use of a genetic marker.

Cultivar-specific effects of pathogen testing on storage root yield of sweet potato, Ipomoea batatas (L.) Lam.

The accumulation and perpetuation of viral pathogens over generations of clonal propagation in crop species such as sweet potato, Ipomoea batatas,inevitably result in a reduction in crop yield and quality. This study was conducted at Bundaberg, Australia to compare the productivity of field-derived and pathogen-tested (PT)clones of 14 sweet potato cultivars and the yield benefits of using healthy planting materials. The field-derived clonal materials were exposed to the endemic viruses, while the PT clones were subjected to thermotherapy and meristem-tip culture to eliminate viral pathogens. The plants were indexed for viruses using nitrocellulose membrane-enzyme-linked immunosorbent assay and graft-inoculations onto Ipomoea setosa. A net benefit of 38% in storage root yield was realised from using PT materials in this study.Conversely, in a similar study previously conducted at Kerevat, Papua New Guinea (PNG), a net deficit of 36% was realised. This reinforced our finding that the response to pathogen testing was cultivar dependent and that the PNG cultivars in these studies generally exhibited increased tolerance to the endemic viruses present at the respective trial sites as manifested in their lack of response from the use of PT clones. They may be useful sources for future resistance breeding efforts. Nonetheless, the potential economic gain from using PT stocks necessitates the use of pathogen testing on virus-susceptible commercial cultivars.

Effects of cultivar on rodent damage in Australian macadamia orchards

The Black rat (Rattus rattus), a serious pest of Australian macadamia orchards has been estimated to cause up to 30% crop damage in Australian orchards. In recent years an increase in the number of commercially available cultivars has seen a change in orchard characteristics in Australia, primarily effecting fruiting and flowering patterns. This has been suggested to affect the feeding behaviour of rodents and in turn altered the damage process. In this study we compare the extent of damage in orchards containing one of three prevalent cultivars (A4/A16, A268 and HAES 344/741) and investigate the influence of these cultivars, particularly their distinctive fruiting traits, on rodent damage within the orchard. We demonstrate that the temporal pattern and extent of damage differs between cultivar types. Newer Australian macadamia cultivars tested in this study were found to be far more susceptible to rodent damage than the older Hawaiian developed cultivars, most likely due to an extended fruiting period and thinner shells. This has resulted in a more sustained period of crop damage than the patterns of crop damage observed in previous Australian studies. Crop damage caused by R. rattus is significantly higher in orchards that maintain high levels of canopy resources through the fruiting season and we postulate that this is due to the extended fruiting periods of the new cultivars used. The maintenance of canopy resource load in turn corresponds to high crop damage, in this study resulting in crop losses of up to 25%.

Agrobacterium tumefaciens-mediated transformation of an elite Australian barley cultivar with virus resistance and reporter genes

Efficient transformation of barley cv. Schooner was achieved using Agrobacterium delivery, hygromycin or bialaphos selection and embryogenic callus. Using this system, transgenic plants were generated that contained either the green fluorescent protein gene, or transgenes derived from barley yellow dwarf (BYDV) and cereal yellow dwarf (CYDV) viruses. Many of these plants contained 1-3 transgene copies that were inherited in a simple Mendelian manner. Some plants containing BYDV and/or CYDV derived transgenes showed reduced virus symptoms and rates of viral replication when challenged with the appropriate virus. The ability to transform Schooner is a significant advance for the Australian barley industry, as this elite malting variety is, and has for the last 15 years been, the most widely grown barley variety in eastern Australia.

Cultivar affects browning susceptibility of freshly cut star fruit slices

Consumption of freshly-cut horticultural products has increased in the last few years. The principal restraint to using freshly-cut carambola is its susceptibility to tissue-browning, due to polyphenol oxidase-mediated oxidation of phenolic compounds present in the tissue. The current study investigated the susceptibility to browning of star fruit slices (Averrhoa carambola L.) of seven genotypes (Hart, Golden Star, Taen-ma, Nota-10, Malasia, Arkin, and Fwang Tung). Cultivar susceptibility to browning as measured by luminosity (L*) varied significantly among genotypes. Without catechol 0.05 M, little changes occurred on cut surface of any cultivars during 6 hour at 25 degrees C, 67% RH. Addition of catechol led to rapid browning, which was more intense in cvs. Taen-ma, Fwang Tung, and Golden Star, with reduction in L* value of 28.60%, 27.68%, and 23.29%, respectively. Browning was more intense in the center of the slices, particularly when treated with catechol, indicating highest polyphenol oxidase (PPO) concentration. Epidermal browning, even in absence of catechol, is a limitation to visual acceptability and indicates a necessity for its control during carambola processing. Care must be given to appropriate selection of cultivars for fresh-cut processing, since cultivar varied in browning susceptibility in the presence of catechol.

Cultivar-specific effects of pathogen testing on storage root yield of sweetpotato, Ipomoea batatas.

The accumulation and perpetuation of viral pathogens over generations of clonal propagation in crop species such as sweetpotato, Ipomoea batatas, inevitably result in a reduction in crop yield and quality. This study was conducted at Bundaberg, Australia to compare the productivity of field-derived and pathogen-tested (PT) clones of 14 sweetpotato cultivars and the yield benefits of using healthy planting materials. The field-derived clonal materials were exposed to the endemic viruses, while the PT clones were subjected to thermotherapy and meristem-tip culture to eliminate viral pathogens. The plants were indexed for viruses using nitrocellulose membrane-enzyme-linked immunosorbent assay and graft-inoculations onto Ipomoea setosa. A net benefit of 38% in storage root yield was realised from using PT materials in this study. Conversely, in a similar study previously conducted at Kerevat, Papua New Guinea (PNG), a net deficit of 36% was realised. This reinforced our finding that the response to pathogen testing was cultivar dependent and that the PNG cultivars in these studies generally exhibited increased tolerance to the endemic viruses present at the respective trial sites as manifested in their lack of response from the use of PT clones. They may be useful sources for future resistance breeding efforts. Nonetheless, the potential economic gain from using PT stocks necessitates the use of pathogen testing on virus-susceptible commercial cultivars. .

Fruit fly host status testing of a new passionfruit cultivar

Fruit fly host status testing of a new passionfruit cultivar.

Reduced fungicide use on a new Australian peanut cultivar, highly resistant to the late leaf spot and rust pathogens

Rust (caused by Puccinia arachidis) and late leaf spot (LLS, caused by Mycosphaerella berkeleyi) can cause significant yield losses in Australian peanut crops. Until recently, all commercial peanut varieties were highly susceptible to these pathogens, but the new Australian cultivar Sutherland has significantly higher levels of resistance than the older cultivars. Field trials were conducted at two sites in Queensland to (a) confirm the improved resistance of cv. Sutherland over another commercial cultivar, Menzies, (b) study the effects of timing of first spray, spray interval and cultivar on disease severity and yield, and (c) develop a suitable fungicide management program for cv. Sutherland. In the 2006 and 2007 trials, rust and LLS developed slower and had lower final disease ratings and AUDPC values on unsprayed plots of cv. Sutherland than on cv. Menzies. The timing of the first spray is critical in managing both rust and late leaf spot, with the results demonstrating that the first fungicide spray on cv. Sutherland should be applied as soon as rust and LLS are first seen on cv. Menzies. In most trials spray intervals of 14 days or 21 days were suitable to effectively control rust and LLS. In years with low disease pressure, few, if any, fungicide applications will be needed to manage the diseases, but in other years up to four sprays may be necessary. © Australasian Plant Pathology Society Inc. 2012.

High-anthocyanin strawberries through cultivar selection

BACKGROUND: Diets high in fruit and vegetables are known to have significant health benefits. This is in part due to the presence of phytochemicals, which possess potential protective health benefits. This study focuses on the ability of strawberries to be bred for higher anthocyanin content. This is a major contributor to the characteristic colour and nutritional value of ripe strawberries, together with phenolic acids, ascorbic acid and total antioxidant capacity. RESULTS: Anthocyanins in five commercial strawberry cultivars and three breeding lines were assessed. This led to the discovery of one breeding line (BL 2006-221) as an exceptional source of anthocyanins (approximate to 1 g kg1 fresh weight), with approximately double the levels of current commercial cultivars. Temperature was shown to influence anthocyanin extraction, with 40 degrees C being the best extraction temperature using the accelerated solvent extraction (ASE) method. Hue angle and anthocyanin concentration showed a good correlation (r2 = 0.69). CONCLUSION: The new breeding line BL 2006-221 has the potential to be used in the development of phytochemically rich strawberry cultivars. Using hue angle as a screening tool for total anthocyanin concentration and extraction of anthocyanins from strawberries by ASE at 40 degrees C would support such cultivar development. (c) 2012 Commonwealth of Australia