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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

Visible and near infrared reflectance spectroscopy (NIRS) for the assessment of flesh foods

Cozzolino Gomez, Daniel January 1998 (has links)
Visible and near infrared (NIR) reflectance and transmission spectra (400 - 2500 nm) of various flesh foods in various presentations were examined for qualitative and quantitative analysis. Discriminant functions for muscle types and animal species were included. Lamb muscles (n: 306), chicken breast and thigh muscles (n: 48), bull and steer muscles (n: 103), raw fish (n: 80), fish meal (n: 700) and fish oil (n: 160) samples were examined in the experiments. INTACT and MINCED presentation to the instrument were compared, as well as type of muscle (<I>longissimus dorsi, infra spinatus, supra spinatus, semimembranosus, semitendinosus, rectus femoris</I>), effect of sex and both longitudinal (LS) and transverse section (TS) of the muscle on the optical properties and Partial Least Squares (PLS) calibrations for gross composition. MINCED presentation to the instrument gave the best results for the NIRS calibrations in all the muscle tissues utilized, while, INTACT presentation showed poorer calibrations. Muscle type and sex affect the calibrations. Raw fish and fish by-products, both fish meal and oil had good NIRS calibrations for the twelve parameters analyzed. The results show that NIRS is acceptable as a method for determining gross composition in a wide variety of flesh foods in MINCED presentation. Principal component analyses (PCA) and Soft Independent Modelling of Class Analogy (SIMCA) were used for the authentication and classification between muscles and among animal species. The conclusions of this work are that NIRS can successfully predict chemical composition in different muscles in MINCED rather than INTACT presentation. Classifications using PCA and SIMCA were excellent tools to authenticate flesh foods.
2

FUNCTIONAL PROPERTIES OF SOLUBLE HYDROCOLLOIDS EXTRACTED FROM <i>THEOBROMA BICOLOR</i><i> </i>(MACAMBO) PROCESSING WASTE AND IN-FIELD PRECOOLING UNITS TO REDUCE PRODUCE WASTE IN THE UNITED STATES

Rae Silver (15307708) 01 December 2023 (has links)
<p dir="ltr">Macambo (<i>Theobroma bicolor</i>) is a relative of cacao that was identified as an underutilized crop in San Martín, Peru with potential for valorization. Current processing for macambo seeds results in waste of two-thirds of the fruit, so the two waste streams (husk and pulp-shell) were characterized by proximal analysis to identify useable components. From the pulp-shell waste, soluble polysaccharides and proteins were extracted. The resulting hydrocolloid formed physical gels that had predominantly solid-like elastic behavior and can partially recover after being deformed by a constant stress. Macambo pulp-shell waste has potential for extracting functional ingredients for thickening, forming gels, retaining water, and stabilizing emulsions.</p><p dir="ltr">One third of food in the United States is never eaten, and waste occurs throughout the food system. Produce is a significant portion of food waste, but shelf life can be extended by optimizing postharvest practices. Conducting precooling in-field at point of harvest with mobile units was proposed by researchers in the field of food waste reduction as an adaptable method to reduce food waste and was evaluated in this study for innovation and barriers to use. Based on expert interviews and a literature review, it was concluded that in-field precooling units are hindered by infrastructure requirements and effective precooling is already optimized at large scale with centralized cooling activities. Flexible cooling technology could be part of a solution for very small growers in the United States and internationally in developing economies, where access to precooling and full cold chain is still lacking.</p>
3

Potato starch modification using the ozone technology / Modificação de amido de batata utilizando a tecnologia do ozônio

Silva, Nanci Castanha da 08 February 2017 (has links)
Starch modification is a widely employed and important technique, allowing to obtain ingredients with different characteristics, expanding the range of applications of starches and bringing competitive advantages for different industries. Despite the production of toxic residues, and despite the increasing concern about environmental issues, the use of chemical agents in starch modification by oxidation is still very popular. Ozone can be a solution to change it, since is a very powerful oxidising agent that can be quickly decomposed into oxygen, whose residues meet the global demand for sustainability. Therefore, it can be a safer alternative for both consumers and environment. In this work the use of ozone in aqueous solution as a starch modification method was evaluated. The effects of the different ozonation times on the structure and properties of the potato starch were investigated. With increasing the ozonation time, it was observed an increase in the carbonyl, carboxyl and reducing sugar contents, as well as a decrease in the pH, apparent amylose content and molecular size, demonstrating that the potato starch processed with ozone was modified in its molecular level. Further, X-ray diffraction analysis showed no significant changes in the relative crystallinity of the granules, while in the microscopy analysis it was observed some alterations in the granules morphology. All these changes directly affected the modified starch properties, resulting in significant differences in the pasting properties, gel texture and paste clarity. The obtained results are promising, since they can prove the effectiveness of using ozone, a still little explored and sustainable method, as an efficient oxidizing agent for starch modification. / Modificação de amidos é uma técnica amplamente empregada e muito importante, permitindo a obtenção de ingredientes com diferentes características, ampliando a gama de aplicação dos amidos e trazendo vantagens competitivas para diferentes indústrias. Apesar da produção de resíduos tóxicos, e apesar da crescente preocupação com as questões ambientais, o uso de agentes químicos na modificação de amidos ainda é muito popular. O ozônio pode ser uma alternativa para mudar este cenário, uma vez que é um poderoso agente oxidante que pode ser rapidamente decomposto em oxigênio, cujos resíduos vão de encontro com a demanda global por sustentabilidade. Portanto, esta pode ser uma alternativa mais segura tanto para os consumidores quanto para o meio ambiente. Neste trabalho avaliou-se o uso de ozônio em solução aquosa como método de modificação de amido. Foram investigados os efeitos de diferentes tempos de ozonização na estrutura e nas propriedades do amido de batata. Com o aumento do tempo de ozonização, foram observados aumento nos teores de carbonila, carboxila e açúcares redutores e diminuição no pH, no teor de amilose aparente e no tamanho molecular, demonstrando que o amido de batata processado com ozônio foi modificado a nível molecular. Além disso, análises de difração de raio-X não mostraram alterações significativas na cristalinidade relativa dos grânulos, enquanto nas análises de microscopia foram observadas algumas alterações na morfologia dos grânulos. Todas estas alterações afetaram diretamente as propriedades do amido modificado, resultando em diferenças significativas nas propriedades de pasta, textura de gel e claridade de pasta. Os resultados obtidos são bastante promissores, uma vez que provam a eficácia de se utilizar o ozônio, um método sustentável e ainda pouco explorado, como um eficaz agente oxidante para a modificação de amido.
4

Potato starch modification using the ozone technology / Modificação de amido de batata utilizando a tecnologia do ozônio

Nanci Castanha da Silva 08 February 2017 (has links)
Starch modification is a widely employed and important technique, allowing to obtain ingredients with different characteristics, expanding the range of applications of starches and bringing competitive advantages for different industries. Despite the production of toxic residues, and despite the increasing concern about environmental issues, the use of chemical agents in starch modification by oxidation is still very popular. Ozone can be a solution to change it, since is a very powerful oxidising agent that can be quickly decomposed into oxygen, whose residues meet the global demand for sustainability. Therefore, it can be a safer alternative for both consumers and environment. In this work the use of ozone in aqueous solution as a starch modification method was evaluated. The effects of the different ozonation times on the structure and properties of the potato starch were investigated. With increasing the ozonation time, it was observed an increase in the carbonyl, carboxyl and reducing sugar contents, as well as a decrease in the pH, apparent amylose content and molecular size, demonstrating that the potato starch processed with ozone was modified in its molecular level. Further, X-ray diffraction analysis showed no significant changes in the relative crystallinity of the granules, while in the microscopy analysis it was observed some alterations in the granules morphology. All these changes directly affected the modified starch properties, resulting in significant differences in the pasting properties, gel texture and paste clarity. The obtained results are promising, since they can prove the effectiveness of using ozone, a still little explored and sustainable method, as an efficient oxidizing agent for starch modification. / Modificação de amidos é uma técnica amplamente empregada e muito importante, permitindo a obtenção de ingredientes com diferentes características, ampliando a gama de aplicação dos amidos e trazendo vantagens competitivas para diferentes indústrias. Apesar da produção de resíduos tóxicos, e apesar da crescente preocupação com as questões ambientais, o uso de agentes químicos na modificação de amidos ainda é muito popular. O ozônio pode ser uma alternativa para mudar este cenário, uma vez que é um poderoso agente oxidante que pode ser rapidamente decomposto em oxigênio, cujos resíduos vão de encontro com a demanda global por sustentabilidade. Portanto, esta pode ser uma alternativa mais segura tanto para os consumidores quanto para o meio ambiente. Neste trabalho avaliou-se o uso de ozônio em solução aquosa como método de modificação de amido. Foram investigados os efeitos de diferentes tempos de ozonização na estrutura e nas propriedades do amido de batata. Com o aumento do tempo de ozonização, foram observados aumento nos teores de carbonila, carboxila e açúcares redutores e diminuição no pH, no teor de amilose aparente e no tamanho molecular, demonstrando que o amido de batata processado com ozônio foi modificado a nível molecular. Além disso, análises de difração de raio-X não mostraram alterações significativas na cristalinidade relativa dos grânulos, enquanto nas análises de microscopia foram observadas algumas alterações na morfologia dos grânulos. Todas estas alterações afetaram diretamente as propriedades do amido modificado, resultando em diferenças significativas nas propriedades de pasta, textura de gel e claridade de pasta. Os resultados obtidos são bastante promissores, uma vez que provam a eficácia de se utilizar o ozônio, um método sustentável e ainda pouco explorado, como um eficaz agente oxidante para a modificação de amido.
5

<strong>Effects of reducing added sugar in sugar-sweetened sodas on  sweet taste perception </strong>

Vinicius Mendanha Valicente (15360424) 29 April 2023 (has links)
<p>  </p> <p>The prevalence of obesity and type 2 diabetes has increased worldwide over the last decades. Sugar-sweetened beverages are especially problematic in the development of obesity and type 2 diabetes. Although the proportion of Americans consuming SSB regularly has been steadily declining, added sugar intake still remains above recommendations by the Dietary Guidelines for Americans and World Health Organization. However, alternatives to SSB exist on the market. For many years, the primary alternatives to SSB were low-calorie sweetened beverages, with sweetness replacers such as aspartame or sucralose. In recent years, options that are less sweet or unsweetened (instead of alternatively sweetened) have become increasingly available. These less-sweet beverages are available in similar packaging and at similar cost as SSB. Thus, these less-sweet beverages may be ideal options to reduce added sugar in the diet. However, few studies have tested switching consumers from SSB to less-sweet beverages (rather than low-calorie sweetened beverages or plain water), and thus the acceptability and implications of this dietary change are minimally documented. In this work, we tested less sweet soda-like beverages and unsweetened sparkling waters for potential to replace SSB. First, we showed that small reductions in sweetness in cola-flavored sodas are noticeable to individuals, meaning that any switch from SSB to less-sweet options will likely need to be overt to the consumer. Next, we conducted a 12-week intervention with adolescents, which showed that replacing SSBs with unsweetened sparkling waters leads to increased liking of less-sweet sodas and shifts in the ideal level of sweetness towards lower sugar concentrations. Building on these results, our final study shows that even just 2 weeks is enough time to induce these changes in acceptance of less sweetness in sodas, if a consumer prefers the higher concentrations of sugar at the beginning of the intervention (a “sweet liker”). Future studies are needed to evaluate how replacing SSB with less sweet options, leading to shifts in sweetness preference, might influence overall diet and risks for diet-related chronic diseases.</p>

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