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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.
141

Novel approaches to automated quality control analyses of edible oils by Fourier transform infrared spectroscopy : determination of free fatty acid and moisture content

Al-Alawi, Ahmed Ali January 2005 (has links)
No description available.
142

Development and Effectiveness of Three Hydrocolloid-Lipid Emulsion Coatings on Preservation of Quality Characteristics in Green Bell Peppers

Ball, Jennifer Ann 23 April 1999 (has links)
Three hydrocolloid-lipid emulsion coatings were developed using Humkote brand partially hydrogenated cottonseed and vegetable oil, and one of three combined hydrocolloid bases: xanthan gum and propylene glycol alginate (xanthan coating), locust bean gum and xanthan gum (locust bean gum coating), and maltodextrin. Sensory testing using a ranking preference test indicated that these coatings had acceptable appearance and palatability. Quality characteristics of green bell peppers (Capsicum annum L. cv. King Arthur) measured during the 5-week storage period included: respiration rates, chlorophyll content, surface color, puncture force, pectin (uronic acid) content, ascorbic acid (AA) and dehydroascorbic acid (DHA) content, and cumulative weight loss. No significant differences between coated and uncoated peppers were noted in tests for respiration, puncture force, hue angle, chlorophyll content, and AA content. Uncoated peppers had significantly inferior moisture retention (p<0.05), which caused them to be unsaleable after 8 days, while coated groups were saleable for an additional 6 to 8 days. Uncoated fruits also had greater uronic acid breakdown (p<0.05) and higher DHA content (p<0.06) than coated peppers. Significant weekly changes (all treatment groups combined) included linear increases in respiration rates (p<0.01) and moisture loss (p<0.01), increasing linear and quadratic trends in uronic acid content (p<0.01 for both trends), increasing quadratic trends for both chlorophyll and AA content (p<0.05, p<0.01, respectively), and decreasing linear and quadratic (p<0.05 for both trends) in DHA content. The only significant difference between coated groups was in chroma value, with maltodextrin coated peppers appearing less vivid than locust bean coated peppers. Overall, all three coatings performed equally well during the storage study. However, coatings with higher lipid content, which included xanthan gum and locust bean gum groups, withstood humidity changes better than the maltodextrin coated peppers. Coating application provided the greatest benefits in terms of texture maintenance through water retention and prevention of pectin breakdown, despite the lack of differences observed in puncture force. Coatings may also have prevented AA oxidation as demonstrated by the higher DHA content in uncoated groups, however AA patterns do not confirm this concept. Future research should be directed toward further minimizing textural changes and maximizing coating durability. / Ph. D.
143

Cultivating Curriculum: How Investing in School Grounds, the Streetscape and Vacant Land as Urban Ecosystems can Address Food Security, the Community and Institutions of Public Education

McAllister, Karen Elizabeth 23 September 2019 (has links)
The 2014 Agricultural Act (Economic Research Division) (aka: The Farm Bill) was an important limelight shone on the issue of access to healthy foods, food education and the correlation between an increasingly unhealthy population and proximity to fresh, healthy food. Further legislation such as the Urban Agricultural Production Act of 2017 has been introduced to leverage the Farm Bill's financial incentives to promote urban agricultural programs and transform vacant land into agricultural use. Specifically, this has become increasingly common in many lower income and disadvantaged communities affected by a lack of access to fresh food stores. Additionally, in response many public schools have pro-actively sought funds to transform their schoolyards into gardens and teaching classrooms (Gamson) in order to provide food literacy and education however, this practice remains the exception. Many children still face a lack of healthy food options or the availability of any fresh food outside of their school environment. What if the standard education facility could be used as a tool to confront not only the architecture of the learning space, but a school-as-ecosystem, representing a neighborhood catalyst to teach through action – addressing comprehensive global issues brought on by food desert environments and a child's perspective about their own health? This thesis explores the possibility of casting the urban ecological net wide- envisioning a timescale for transforming public spaces and school grounds using green infrastructure practices, biological remediation, planning for changes in transportation technology and the expectations of a public education and child's perception about their environment. Emphasizing a broad focus on all of the potential sites for food production in the city (including the school, schoolyard and what they represent to the community), surfaces a multi-functioning methodology encompassing community identity, amenity, ecology, infrastructure and beauty envisions what could become of urban areas in the future. The primary goal is to educate future generations in the value of the food network and to give them the kind of direct hands-on experience that educators emphasize while concurrently nourishing urban communities through development of a project carried out in common, one that has health benefits for the population, that engenders a sense of long-term pride, and that empowers people to make change in their environment, even in modest or temporary ways. The idea that school design can encourage and facilitate, hinder and inhibit behaviors at school, and the architectural symbolism of schools can have a profoundly wider impact on children and their behaviors in and outside of school (Tucker). There is a significant psychological difference in learning about the environment, for the environment and in the environment (Malone). Creating public space focused on individual learning and the physical and mental health of the individual aims to balance the scales of social economic injustices. It is going to take every effort from the hyper-localized to city-wide and even regional scales to make significant urban changes to create a taxonomy of spaces to support the growth of our cities while simultaneously educating young minds on the value of understanding our ecological relationship to the city and surrounding environment. / Master of Science / The 2014 Agricultural Act (Economic Research Division) (aka: The Farm Bill) was an important limelight shone on the issue of access to healthy foods, food education and the correlation between an increasingly unhealthy population and proximity to fresh, healthy food. Further legislation such as the Urban Agricultural Production Act of 2017 has been introduced to leverage the Farm Bill’s financial incentives to promote urban agricultural programs and transform vacant land into agricultural use. Specifically, this has become increasingly common in many lower income and disadvantaged communities affected by a lack of access to fresh food stores. Additionally, in response many public schools have pro-actively sought funds to transform their schoolyards into gardens and teaching classrooms (Gamson) in order to provide food literacy and education however, this practice remains the exception. Many children still face a lack of healthy food options or the availability of any fresh food outside of their school environment. What if the standard education facility could be used as a tool to confront not only the architecture of the learning space, but a school-as-ecosystem, representing a neighborhood catalyst to teach through action – addressing comprehensive global issues brought on by food desert environments and a child’s perspective about their own health? This thesis explores the possibility of casting the urban ecological net wide- envisioning a timescale for transforming public spaces and school grounds using green infrastructure practices, biological remediation, planning for changes in transportation technology and the expectations of a public education and child’s perception about their environment. Emphasizing a broad focus on all of the potential sites for food production in the city (including the school, schoolyard and what they represent to the community), surfaces a multi-functioning methodology encompassing community identity, amenity, ecology, infrastructure and beauty envisions what could become of urban areas in the future. The primary goal is to educate future generations in the value of the food network and to give them the kind of direct hands-on experience that educators emphasize while concurrently nourishing urban communities through development of a project carried out in common, one that has health benefits for the population, that engenders a sense of long-term pride, and that empowers people to make change in their environment, even in modest or temporary ways. The idea that school design can encourage and facilitate, hinder and inhibit behaviors at school, and the architectural symbolism of schools can have a profoundly wider impact on children and their behaviors in and outside of school (Tucker). There is a significant psychological difference in learning about the environment, for the environment and in the environment (Malone). Creating public space focused on individual learning and the physical and mental health of the individual aims to balance the scales of social economic injustices. It is going to take every effort from the hyper-localized to city-wide and even regional scales to make significant urban changes to create a taxonomy of spaces to support the growth of our cities while simultaneously educating young minds on the value of understanding our ecological relationship to the city and surrounding environment.
144

Effect of flour protein content on the utilization of shortening and cellulose in biscuits

Robertson, Katherine Anne 13 October 2010 (has links)
Biscuits were prepared from eighteen different recipe formulations. The biscuits were made from flour containing 7.53%, 8.99%, and 10.05% protein with 30, 40, and 50 grams of shortening and 0 or 2.2 grams of microcrystalline cellulose (MCC). Biscuit quality was assessed by objective and sensory evaluation. The caloric content of the biscuits was also determined by bomb calorimetry. No significant differences were detected in biscuit volume, crumb and crust color, or tenderness. The biscuits prepared with lower levels of shortening were moister than the biscuits prepared with higher levels of shortening. Wo significant differences were found by sensory panelists with regard to evenness of exterior color, aroma, evenness of cell structure, size of cell structure, interior color, center moistness, tenderness, biscuit flavor, or aftertaste. Flakiness and exterior color were found to be significantly different. Biscuits with added MCC were detected to be less flaky. Biscuits prepared from medium protein level flour and low-shortening with MCC were darker than high-shortening biscuits without MCC. High-protein, high-shortening biscuits with MCC were darker than medium-protein, high-shortening biscuits without MCC. The caloric content of the biscuits prepared with lower amounts of shortening was found to be significantly less than biscuits prepared with the higher levels of shortening. In conclusion, high quality biscuits can be produced from flour of varying protein content with less shortening and without the incorporation of MCC. / Master of Science
145

Edible Green Infrastructure in the United States: Policy at the Municipal Level

Coffey, Sarah E. 08 May 2020 (has links)
Urbanization can negatively affect the capacity of ecosystems to provide services that support human life. Edible green infrastructure (EGI) can increase cultural and environmental services in urban and peri-urban communities. Instrumental in the use of EGI are local governments, who are in a position to pass supportive policies. For this research, we completed a qualitative study of EGI policy processes in U.S. cities and a mixed-methods study of EGI challenges and opportunities in small towns. Our first objective was to understand how and why EGI policy develops. We interviewed twelve policy actors from six U.S. cities that have formalized EGI ordinances. Major drivers of EGI policy were: 1) improving public health; 2) securing land tenure; 3) managing vacant lands; 4) accommodating for population growth; and 5) the local food movement. Common policymaking steps included: 1) local communities initiate EGI policy process; 2) city governments respond by working with communities to draft EGI ordinances; 3) abrupt changes to land use policies result in a policy image supportive of EGI as a public land management strategy; and 4) during emergence of the new land use paradigm, incremental changes reinforce this image. We also learned how certain challenges and policy actor recommendations for minimizing obstacles affect the policy process. Our second objective was to understand EGI adoption in small towns. We surveyed 68 mayors of small towns (<25,000) in Virginia to study local leader perspectives regarding implementation and policy. The greatest perceived barrier to EGI adoption was long-term maintenance, whereas opportunities included civic benefits such as education and community-building. Most towns had not intentionally used EGI on public land, nor did they have compatible land use codes. Open-ended responses suggest that mayors have different views about the role policy should play in EGI adoption. We used mayoral perceptions about the constituent support for public green space, the implementation of edible woody perennial species, and available public space for EGI to group towns into unique types. Four groups were identified in a K-means cluster analysis: 1) Ambivalent and Resource-Poor; 2) Optimistic and Capable; 3) Doubtful and Unsupported; and 4) Unsure with Potential. One-way ANOVA and Tukey's HSD post-hoc analysis (α=0.05) showed that Optimistic and Capable were significantly more likely than Doubtful and Unsupported to intend to plant EGI and benefit from government support for edible, woody perennials on public land. EGI may be more practical for towns with greater backing for public green space, more available land, and higher rates of favorable attitudes. / Master of Science / The global movement of people from rural to urban and suburban areas has impacted ecosystem health and human well-being. A land management strategy that can improve environmental and public health is edible green infrastructure (EGI), which is small-scale food production in and around built structures. Local governments can pass policies that increase the use of EGI in public spaces. To learn more about how local governments view EGI and the role that policy might play, we completed two studies. In our first study, we interviewed 12 people from 6 U.S. cities who were involved in the development of EGI policies. The purpose of this study was to learn how and why cities pass EGI policies. Reasons for policy adoption included: 1) improving public health for their residents; 2) ensuring EGI as a permanent rather than temporary land use; 3) finding a better use for vacant properties; 4) setting aside green space for current and future populations; and 5) increasing local and healthy food access. Cities shared the following policy development steps: 1) local community leaders demonstrated that EGI policy was needed; 2) government leaders worked together with residents to draft an EGI ordinance; 3) ordinances were passed that significantly changed how public land could be used; and 4) they passed other, smaller policies to make the use of EGI easier for residents. In our second study, we surveyed 68 mayors of small towns (< 25,000 people) in Virginia, U.S. The purpose of this study was to learn what local leaders think about the use of EGI in the public spaces and whether EGI policies would be useful. Long-term maintenance was the biggest barrier and the greatest opportunities included education, recreation, social gathering, and community building. Mayors had differing opinions on whether policies pertaining to EGI on public land were a good idea for their towns, and several pointed out that residents already had access to private land for food production. Using mayors' responses, we grouped towns based on the following characteristics: 1) how much public land could be used for food production; 2) how supportive residents were of existing green space; and 3) how residents thought about the use of EGI on public land. We found that small towns in Virginia could be described as; 1) Ambivalent and Resource-Poor; 2) Optimistic and Capable; 3) Doubtful and Unsupported; or 4) Unsure with Potential. "Optimistic and Capable" towns were more likely to be supported by municipal policies and budgets and to use EGI for managing public land, whereas "Doubtful and Unsupported" towns were least likely to be supported by local government and to use EGI. In summary, EGI may be more practical for towns with greater backing for public green space, more available land, and more favorable views on food production on public land.
146

Evaluation of Two Lipid-Based Edible Coatings For Their Ability to Preserve Post Harvest Quality of Green Bell Peppers

Ball, Jennifer Ann 05 September 1997 (has links)
Two lipid-based edible coatings, Apex B (AC Humko, Memphis, TN) and Durafresh (Pacrite, Ecoscience Produce Systems, Orlando, Fl) were evaluated for their ability to preserve post harvest quality changes in green bell peppers (Capsicum annum L. cv. King Arthur). Post harvest storage quality conditions tested included respiration rates, weight, color and texture changes, and stability of ascorbic acid (AA) and dehydroascorbic acid (DHA) content. Results indicated that no appreciable changes between days or treatment groups occurred in three of the parameters tested: weight, texture, and hue angle (p>0.05 for all parameters). Significant weekly changes were seen in respiration rates, dehydroascorbic acid content, and chromaticity values. Respiration rates and DHA were significantly higher during the last two weeks of the study (p=0.0001, p=0.0001 respectively). Chromaticity values were significantly lower, indicating a more faded color on the 14th day of the study alone (p=0.0097). Initial AA levels were much lower than expected (average initial content=78.72mg/100g). Significant differences between coated and uncoated pepper groups were seen in AA and DHA levels. AA content was found to be significantly lower in coated peppers (p=0.0279), while DHA levels were significantly higher in coated groups (p=0.0126). Overall, coated groups differed little from uncoated counterparts, except in the area of vitamin content in which the coated peppers showed an increase in vitamin breakdown. Despite the results, modifications of lipid coatings are needed, such as creating bilayer and composite coatings that contain either polysaccharide or protein constituents to enhance coating effectiveness. / Master of Science
147

Desarrollo de recubrimientos comestibles con actividad antifúngica en frutos cítricos

Valencia Chamorro, Silvia Azucena 22 October 2009 (has links)
En la industria citrícola, las pérdidas económicas más importantes en poscosecha se deben las podredumbres verde y azul, causadas por los hongos Penicillium digitatum (Pers.:Fr.) Sacc. y Penicillium italicum Wehmer. Durante muchos años, se utilizaron ampliamente los fungicidas químicos para el control de estas enfermedades. Sin embargo, la preocupación de los consumidores por el uso excesivo y prolongado de estos productos para el control de las podredumbres ha orientado a los investigadores a buscar métodos alternativos no contaminantes que no depositen residuos peligrosos ni contaminen el ambiente. El uso de películas y recubrimientos comestibles es un método respetuoso con el ambiente que incrementa la vida útil de muchos alimentos incluidas las frutas y verduras. Sin embargo, muy poca investigación se ha enfocado al desarrollo de recubrimientos comestibles compuestos con la adición de compuestos antifúngicos como un nuevo método para controlar las enfermedades poscosecha en frutos cítricos frescos. El objetivo general de esta tesis doctoral fue desarrollar nuevos recubrimientos comestibles compuestos con la adición de aditivos alimentarios antifúngicos para el control de las podredumbres verde y azul en cultivares de cítricos comercialmente importantes. Primero, se desarrollaron las nuevas películas comestibles compuestas en base a hidroxipropil metilcelulosa (HPMC)-lípido con la adición de aditivos alimentarios o compuestos generalmente reconocidos como seguros (GRAS, por sus siglas en inglés), y se seleccionaron de acuerdo a su capacidad de formar emulsiones estables. Las películas se evaluaron por su actividad in vitro contra P. digitatum y P. italicum y sus propiedades mecánicas y de barrera (Capítulo 1). Luego, las emulsiones seleccionadas se usaron para pruebas in vivo en especies y cultivares de cítricos comercialmente importantes y se determinó su actividad antifúngica curativa (fruta recubierta después de la inoculación) y preventiva (fruta recubierta antes de la inoculación fungíca) contra las podredumbres verde y azul (Capítulo 2). / Valencia Chamorro, SA. (2009). Desarrollo de recubrimientos comestibles con actividad antifúngica en frutos cítricos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/6286
148

Starch based coatings with thyme essential oil for fruit preservation

Sapper, Mayra Ileana 29 July 2019 (has links)
Tesis por compendio / [ES] En esta Tesis, se han analizado diferentes estrategias para adaptar las formulaciones de almidón con el fin de obtener recubrimientos útiles en la conservación poscosecha de frutas. El almidón se sustituyó parcialmente por gomas de origen microbiano (xantano, gelano y pululano) para mejorar las propiedades funcionales de las películas. La adición de gelano a la matriz de almidón, redujo su capacidad de adsorción de agua y la permeabilidad al vapor de agua y oxígeno. Tuvo un efecto positivo en las propiedades mecánicas, mejorando su resistencia a la rotura y previniendo la retrogradación. La goma xantana aumentó la resistencia a la rotura de las películas de almidón, pero no redujo su capacidad de adsorción de agua y la permeabilidad al vapor de agua. La sustitución del almidón por un 10 o 20% de gelano, podría ser una buena estrategia para obtener películas con propiedades más adecuadas con fines de envasado/recubrimiento de alimentos. Se analizaron películas mezcla de almidón-gelano con aceite esencial de tomillo (EO), con el objetivo de proporcionar actividad antifúngica a las formulaciones. El aceite se incorporó mediante emulsificación directa o encapsulado en liposomas de lecitina. Las películas mostraron un efecto antifúngico en las pruebas in vitro contra A. alternata y B. cinerea. La encapsulación del EO promovió una mayor retención del aceite, mejorando su actividad antifúngica, siendo éstas más efectivas contra B. cinerea que contra A. alternata. Una mayor proporción de almidón en el film dio lugar a mayor crecimiento fúngico a baja concentración del compuesto activo. Todas las películas exhibieron alta capacidad de barrera al oxígeno. La lecitina mejoró la capacidad de barrera al vapor de agua y redujo la rigidez, la resistencia a la rotura y la extensibilidad. Las películas con EO encapsulado, con una proporción de almidón-gelano de 8:2, fueron las más efectivas para controlar el crecimiento fúngico. Para aplicar las formulaciones de almidón-gelano como recubrimientos, se analizaron las propiedades superficiales de distintas frutas (manzana, tomate y caqui), y el coeficiente extensibilidad de las formulaciones sobre la superficie de la frutas, en función de la concentración de Tween 85. Las pieles de las frutas evaluadas se comportaron como superficies de baja energía. La adición de Tween 85 a las muestras sin EO, tuvo un efecto positivo en el ángulo de contacto y la tensión superficial. Sin embargo, cuando contenían EO, emulsionado o encapsulado en lecitina, el surfactante ejerció un efecto negativo en estas propiedades, dependiendo de su concentración. Las formulaciones con EO, emulsionado o encapsulado, no requirieron surfactante para mejorar su extensibilidad, mientras que la adición de Tween 85 a una concentración de 5x104 mg/L, mejoró notablemente esta propiedad en formulaciones S:G sin EO. Recubrimientos a base de almidón-gelano, con o sin EO emulsionado o encapsulado en liposomas de lecitina, fueron aplicados en manzanas y caquis. Los recubrimientos no redujeron la pérdida de peso en las manzanas, pero evitaron la pérdida de agua en los caquis. No se observó un efecto significativo de los recubrimientos en las tasas de respiración y el cociente de respiración de los caquis, mientras que estos parámetros aumentaron en manzanas. En los ensayos in vivo, los recubrimientos sin lecitina redujeron la incidencia y severidad de la mancha negra por A. alternata en caquis, y la severidad del moho gris por B. cinerea en manzanas. A pesar de su acción antifúngica in vitro, el EO no ejerció un efecto antifúngico adicional en la fruta. Esto podría explicarse por las interacciones particulares entre los componentes del recubrimiento, la superficie de la fruta y el patógeno. Los recubrimientos a base de almidón-gelano sin lecitina ni EO podrían aplicarse en caquis para controlar la pérdida de peso y reducir la incidencia de A. alternata. / [CA] En esta Tesi, s'han analitzat diferents estratègies per a adaptar les formulacions de midó a fi d'obtenir recobriments útils per a la conservació postcollita de fruites. El midó es va substituir parcialment per gomes d'origen microbià (xantano, gelano i pululano) per a millorar les propietats funcionals de les pel¿lícules. L'addició de gelano a les pel¿lícules de midó, va reduir la seua capacitat d'adsorció d'aigua. També va tindre un efecte positiu en les propietats mecàniques, i va millorar la seua resistència a la ruptura i va prevenir els fenòmens de retrogradació. La goma de xantano també va augmentar la resistència a la ruptura de les pel¿lícules de midó, però no va reduir la seua capacitat d'adsorció d'aigua i la permeabilitat al vapor d'aigua. La substitució del midó per un 10 o 20% de gelano, podria ser una bona estratègia per a obtenir pel¿lícules amb propietats més adequades per al envasat/recobriment d'aliments. S'analitzaren les pel¿lícules mescla de midó-gelano amb oli essencial de timó (EO), amb l'objectiu de proporcionar activitat antifúngica a les formulacions. L'oli es va incorporar mitjançant emulsificació directa o encapsulat en liposomes de lecitina. Estes pel¿lícules van mostrar un efecte antifúngic en les proves in vitro contra A. alternata i B. cinerea. L'encapsulació de l'EO en els liposomes de lecitina va promoure una major retenció de l'oli i va millorar la seua activitat antifúngica, sent estes més efectives contra B. cinerea que contra A. alternata. En les formulacions amb una major proporció de midó amb baix contingut en compost actiu va haver un major creixement fúngic. Totes les pel¿lícules van exhibir alta capacitat de barrera a l'oxigen. La presència de lecitina va millorar la capacitat de barrera al vapor d'aigua i va reduir la rigidesa, la resistència a la ruptura i l'extensibilitat. Les pel¿lícules amb EO encapsulat, amb una proporció de midó-gelano 8: 2, van ser les més efectives per a controlar el creixement fúngic. Amb l'objectiu d'aplicar les formulacions de midó-gelano com a recobriments, es van analitzar les propietats superficials de distintes fruites (poma, tomaca i caqui), i el coeficient d'extensibilitat d'estes formulacions sobre la superfície de la fruita, en funció de la concentració de Tween 85. Les pells de les fruites avaluades es van comportar com a superfícies de baixa energia. L'addició de Tween 85 a les formulacions sense EO, va tenir un efecte positiu en els angles de contacte i la tensió superficial. En presència de l'EO, emulsionat o encapsulat en liposomes de lecitina, el tensioactiu va exercir un efecte negatiu en estos valors, depenent de la seua concentració. Els recobriments amb EO, emulsionat o encapsulat, no van requerir tensioactiu per a millorar la seua extensibilitat, mentre que l'addició de Tween 85 a una concentració de 5x104 mg/L, va millorar notablement esta propietat en les formulacions sense EO. Recobriments a base de midó-gelano, amb o sense l'agregat d'EO emulsionat o encapsulat en liposomes, van ser aplicats en pomes i caquis.. Els recobriments no van reduir la pèrdua de pes en les pomes, però van evitar la pèrdua d'aigua en els caquis. No es va observar un efecte significatiu dels recobriments en les taxes de respiració i el quocient de respiració dels caquis, mentre que les taxes i el quocient de respiració van augmentar en les pomes. En els assajos in vivo, els recobriments sense lecitina van reduir la incidència i severitat de la taca negra per A. alternata en els caquis, i la severitat de la floridura grisa per B. cinerea en les pomes. No obstant això, la incorporació de l'EO no va exercir un efecte antifúngic addicional en la fruita. Açò podria explicar-se per les interaccions particulars entre els components del recobriment, la superfície de la fruita i el patogen. Els recobriments a base de midó-gelano sense lecitina o EO de timó podrien aplicar-se en caqui / [EN] In this Thesis, different strategies have been analysed to tailor starch formulations for the purposes of obtaining useful coatings in postharvest fruit preservation. Starch was partially substituted by microbial gums (xanthan, gellan, and pullulan) in order to improve film functional properties. Moisture sorption capacity and water vapour and oxygen permeability were reduced by the presence of gellan gum in the starch films. It also had a positive effect on the tensile properties, enhancing the films' strength and resistance to break and preventing retrogradation phenomena. Xanthan gum increased the tensile strength of the starch films, but did not reduce their water sorption capacity and water vapour permeability. Functional properties were not notably improved by the addition of pullulan. Then, 10 and 20 % starch could be substituted by gellan gum to obtain films with more adequate properties for food packaging/coating purposes. Starch-gellan blend films containing thyme essential oil (EO) were also studied in order to provide antifungal activity to the formulations. This was incorporated either by direct emulsification or encapsulated in lecithin liposomes. These films exhibited antifungal effect in in vitro tests against A. alternata and B. cinerea. The encapsulation of the EO in lecithin liposomes allowed for greater EO retention in the films, enhancing their antifungal activity, which were more effective against B. cinerea than against A. alternata. The antifungal action was slightly affected by the polymer matrix composition. Thus, the greatest starch ratio enhanced the fungal growth when the content of the active compound was low. All the films exhibited high oxygen barrier capacity. The presence of lecithin enhanced their water vapour barrier capacity and reduced the film stiffness, resistance to break and extensibility. The films with lecithin-encapsulated EO, with a starch-gellan ratio of 8:2, were the most effective at controlling fungal growth. In order to apply these starch-gellan formulations as fruit coatings, the surface properties of apple, tomato and persimmon, and the spreadability coefficient of these liquid formulations on the fruit surface, were analysed as a function of the concentration of Tween 85, as surfactant. The fruit skins behaved as low-energy surfaces. The values of the contact angles and surface tension of EO-free formulations were positively influenced by the addition of Tween 85. However, in the presence of emulsified or lecithin-encapsulated thyme EO, the surfactant exerted a negative effect, depending on its concentration. Coating-forming systems containing emulsified or encapsulated EO did not require surfactant to improve their already good spreadability, while Tween 85 at 5x104 mg/L notably improved this property in EO-free formulations. Starch-gellan coatings, containing or not emulsified or lecithin-encapsulated EO, were applied on apples and persimmons. Coatings did not reduce the weight loss in apples, but they prevented water loss in persimmons. In contrast, no significant effect of the coatings was observed on respiration rates and respiration quotient of persimmons, whereas they increased the respiration rates and quotient in apples. Coatings did not affect the changes in fruit firmness either in apples or persimmons. In the in vivo assays, the coatings without lecithin reduced the incidence and severity of black spot caused by A. alternata in persimmons, and the severity of grey mould caused by B. cinerea in apples. The incorporation of EO did not exert an additional antifungal effect on the fruit and seemed to exert a negative effect on some other fruit quality attributes. This could be explained by the particular interactions of the coating components, fruit surface and pathogen. Starch-gellan coatings without lecithin or thyme EO could be used in persimmons to control weight loss and reduce the incidence of infections caused by A. alternata. / This work has been founded by the “Ministerio de Economía y Competitividad” of Spain, through the Project AGL2016-76699-R and the “Conselleria de Educación, Investigación, Cultura y Deporte de la Generalitat Valenciana” trough the Santiago Grisolía grant GRISOLIA/2015/001. / Sapper, MI. (2019). Starch based coatings with thyme essential oil for fruit preservation [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/124342 / Compendio
149

Attitude towards the cultivation and utilisation of indigenous leafy vegetables in rural communities

Mungofa, Nyarai 12 1900 (has links)
Food insecurity remains a major challenge affecting the rural poor households in South Africa. The consumption of green leafy vegetables is important to address micronutrients deficiency in rural communities and, at the same time, it contributes to fibre intake. This study investigated the people’s attitude towards the cultivation and utilisation of ILVs in rural communities. A cross-section survey study was conducted among 1 000 respondents in randomly selected households in communities. The majority of respondents were not willingly consuming ILVs. This is because most consumers were black and of the low-income group. ILVs that are consumed grow mainly in the wild. The regular consumption of these vegetables as indicated in this study is interesting, as this will help in mitigating micronutrient deficiency. Furthermore, these vegetables could be incorporated in formulated food to improve iron and zinc, especially in infant foods formulation. Based on the findings of this study it would be important to find ways of encouraging cultivation of ILVs for both nutrition and as income generating activities. / Life and Consumer Science / M.CS.
150

The use of indigenous plants as food by a rural community in the Eastern Cape : an educational exploration

Shava, Soul January 2000 (has links)
Looking at the use of plants as food reflects how humankind has fashioned nature. There has been a significant change in production patterns from hunter-gathering through subsistence agriculture to technologically advanced commercial agriculture with a subsequent reduction in the diversity of plants used as food. A parallel trend in consumption patterns has occurred, from home-based food processing for subsistence through small- scale production to large-scale industrial processing and the commodification of food. The overall result of such trends is a narrowing of the food resource base and an increasing reliance on processed foods at the expense of traditional diets, accompanied by increasing diet-related health risks. This research is an ethnographic case study on the use of indigenous food plants by the community of Tuku A village in the Eastern Cape using interviews and observations as the main data collecting strategies. A nutritional analysis of some wild food plants was also carried out. An inventory of more than 70 food plant species was compiled, with the knowledge of such plants found among both the elderly and the youth. The incorporation of this knowledge into education systems is recommended. Of the wild food plants documented, some were non-indigenous indicating the dynamic nature of indigenous knowledge. Some wild spinach were left to grow amongst cultivated food plants, hinting at some form of ‘domestication’ in process. This observation together with the observation that wild fruit trees were selectively conserved highlights the possibility of the continued use of wild food contributing to conservation of botanical diversity. Community use of indigenous food was found to be diminishing. Stigmatisation of indigenous food plants, urbanisation, formal education, changes in lifestyle, and media were some of the factors possibly influencing this dietary shift. The community made links between diet and health, which correspond to modern scientific knowledge, with modern diet being lamented for ill health. The nutritional analysis revealed that wild food plants do contain essential dietary nutrients, an area recommended for further research.

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