The present study was aimed at extending our knowledge of the antioxidative properties of the milk protein products, whey protein isolate (WPI) and sodium caseinate (NaCas), in oil-in-water (O/W) emulsions rich in polyunsaturated fatty acids (PUFAs). In particular, the objective was to contribute to our understanding of the compositional and processing factors that influence the oxidative stability of protein-stabilised O/W emulsions. Linoleic acid (approximately 60 %) was used as the lipid for the oil phase (10.6 %). The emulsion samples were usually incubated at 50 °C to accelerate lipid oxidation. Lipid oxidation indicators were lipid hydroperoxides and headspace hexanal, determined by solid phase microextraction (SPME) combined with gas chromatography (GC). WPI- or NaCas-stabilised emulsions were prepared using a wide range of protein concentrations (0.5, 1.0, 2.0, 3.0, 4.0, 7.0 or 10.0 %) at two droplet sizes (d32 = 0.31 and 0.65 µm). In general, higher lipid oxidation levels were found for the larger droplet size. Increasing protein concentration led to a decrease in the lipid oxidation rate. The greatest decrease in lipid hydroperoxide levels (values after 4 h) occurred at up to 4.0 % protein concentration. The greatest decrease in hexanal levels (values after 24 h) occurred at up to 4.0 % protein concentration in WPI emulsions (0.31 µm). The hexanal levels were more independent of the protein concentration in the other emulsion types. The hexanal level decreased at protein concentrations > 4.0 % in NaCas emulsions (0.31 and 0.65 µm) and at protein concentrations > 7.0 % in WPI emulsions (0.65 µm). The difference between lipid hydroperoxide generation in emulsions with small and large droplet sizes decreased with increasing protein concentration. This effect was more pronounced in NaCas emulsions. In general, NaCas was a better inhibitor of lipid oxidation than WPI, but WPI appeared to be the better antioxidant at some droplet size/protein concentration combinations. The protein in the continuous phase, i.e. the unadsorbed protein, played an important role in lipid oxidation. In principal, the lipid hydroperoxide and hexanal levels showed the same development over the continuous phase protein concentration as over the protein concentration in WPI and NaCas emulsions (d32 = 0.31 µm). A low NaCas level in the continuous phase already led to a relatively low hexanal level, whereas a higher WPI level was required. When NaCas solution was added to a WPI emulsion or WPI solution was added to a NaCas emulsion, a synergistic antioxidative effect was observed. The high molecular weight fractions (molecular weight = 12000-14000) of WPI and NaCas contained pro-oxidative metal ions that contributed to lipid oxidation in the emulsions. An enrichment of NaCas emulsions with the low molecular weight fraction of NaCas (with a molecular weight = 12000-14000) notably inhibited lipid oxidation. An enrichment of WPI emulsions with the low molecular weight fraction of WPI (with a molecular weight = 12000-14000) also seemed to inhibit lipid oxidation, but the effect was not significant. The protein solutions were enriched with these fractions before emulsion preparation. Pure WPI solution or mixed WPI/NaCas (1:1, weight/weight) solution with 1.12 or 2.24 % protein concentration was heated at 84 °C for up to 40 min, cooled and then used to prepare emulsions. Lipid oxidation was generally not affected by the heat treatment or the degree of whey protein denaturation. However, at the lower WPI concentration, more hexanal was produced for the longer heating times (20, 30 and 40 min) and this appeared to be connected with the physical instability of the emulsions. Greater oxidative stability was found at the higher protein concentration and when the proteins were mixed, pointing to a possible synergistic antioxidative effect of WPI and NaCas. The addition of the free radical source 2,2’-azobis(2-amidinopropane) dihydrochloride (AAPH) greatly increased the oxygen uptake and the generation of lipid hydroperoxides in the emulsions. The oxidative stability increased with increasing protein concentration (1.0, 4.0 and 7.0 %). NaCas had a greater antioxidative effect than WPI. The inhibition of oxygen uptake appeared to be largely influenced by the free-radical-scavenging activity of the system, determined by the protein type and the protein concentration, as the radicals were produced linearly over time and oxygen was consumed linearly over time. It can therefore be concluded that free-radical-scavenging activity represents a major antioxidative mechanism of the milk proteins. Oxygen was consumed much faster in emulsions than in protein solutions when the same level of AAPH was incorporated. In a WPI (1.0 % protein) emulsion, much lower levels of protein hydroperoxides than of lipid hydroperoxides developed. This pointed to a much greater reactivity of linoleic acid than of the milk proteins with oxygen. In contrast, the exposure of WPI to oxidising linoleic acid in an emulsion (1.0 % protein) or to AAPH in aqueous solution led to oxidative damage of the whey proteins, indicated by the loss of amino acids. The loss of specific amino acids was different for proteins in the continuous phase or cream phase of an emulsion or in WPI solution. The present study confirms the antioxidative potential of WPI and NaCas and gives new insights into their functionality as oxidative stabilisers in O/W emulsions.

Milk is provided to new borns as their first food source and it contains essential nutrients, vitamins and other beneficial components, such as enzymes and antibodies that are required for rapid growth and development of the new born and for sustained growth over time. Milk contains two main types of proteins; casein proteins and whey proteins. Although casein proteins account for up to 80% of the proteins found in bovine milk, it is the whey protein that has become of high interest because of its bioactive content. Whey, a very watery mixture of lactose, proteins, minerals and trace amounts of fat, is formed from milk when the milk is coagulated and/or the casein proteins are removed from the milk. Bovine whey protein, including both the acidic and basic fractions (low and high isoelectric point, respectively), has previously been studied in vitro (cell based) and in vivo (using rats) for its impact on bone to determine if it can help improve bone mineral density and help reduce the risk of developing bone diseases, such as osteoporosis. Bone is constantly undergoing a remodelling process of being dissolved and reformed and the two main cell types responsible for this bone remodelling process are mature osteoclasts, which dissolve (resorb) bone, and osteoblasts, which reform the bone. Prior work has shown that acidic protein fractions derived from different sources of whey protein concentrate (WPC) have both in vivo and in vitro activity on bone, particularly anti-resorptive properties. However, the component(s) which confer activity have not yet been identified. In this thesis, work was undertaken to better understand the analytical composition of three types of WPC (cheese, mineral acid and lactic acid) and their associated acidic protein fractions and relate this to bone activity in the hope of identifying where the activity lies. Bone activity was assessed using in vitro screening with osteoblast cells (MC3T3-E1) and osteoclast cells (RAW 264.7). Comparison of the cell-based bone activity of the parent WPCs and corresponding acidic fractions indicated that the acidic fractions derived from both mineral acid and lactic WPC were superior in their ability to inhibit osteoclast development. Although compositional data was complex and definitive correlations with both bone bioactivities could not be made, it appeared that elements common to both the acidic fractions were a higher proportion of GLYCAM-1 and bone sialoprotein-1 (osteopontin). Further studies to more closely investigate the bone bioactivity of the acidic fractions are warranted.

Milk is provided to new borns as their first food source and it contains essential nutrients, vitamins and other beneficial components, such as enzymes and antibodies that are required for rapid growth and development of the new born and for sustained growth over time. Milk contains two main types of proteins; casein proteins and whey proteins. Although casein proteins account for up to 80% of the proteins found in bovine milk, it is the whey protein that has become of high interest because of its bioactive content. Whey, a very watery mixture of lactose, proteins, minerals and trace amounts of fat, is formed from milk when the milk is coagulated and/or the casein proteins are removed from the milk. Bovine whey protein, including both the acidic and basic fractions (low and high isoelectric point, respectively), has previously been studied in vitro (cell based) and in vivo (using rats) for its impact on bone to determine if it can help improve bone mineral density and help reduce the risk of developing bone diseases, such as osteoporosis. Bone is constantly undergoing a remodelling process of being dissolved and reformed and the two main cell types responsible for this bone remodelling process are mature osteoclasts, which dissolve (resorb) bone, and osteoblasts, which reform the bone. Prior work has shown that acidic protein fractions derived from different sources of whey protein concentrate (WPC) have both in vivo and in vitro activity on bone, particularly anti-resorptive properties. However, the component(s) which confer activity have not yet been identified. In this thesis, work was undertaken to better understand the analytical composition of three types of WPC (cheese, mineral acid and lactic acid) and their associated acidic protein fractions and relate this to bone activity in the hope of identifying where the activity lies. Bone activity was assessed using in vitro screening with osteoblast cells (MC3T3-E1) and osteoclast cells (RAW 264.7). Comparison of the cell-based bone activity of the parent WPCs and corresponding acidic fractions indicated that the acidic fractions derived from both mineral acid and lactic WPC were superior in their ability to inhibit osteoclast development. Although compositional data was complex and definitive correlations with both bone bioactivities could not be made, it appeared that elements common to both the acidic fractions were a higher proportion of GLYCAM-1 and bone sialoprotein-1 (osteopontin). Further studies to more closely investigate the bone bioactivity of the acidic fractions are warranted.

Orientador: Ana Lúcia Barretto Penna / Banca: Elisa Helena Giglio Ponsano / Banca: Célia Maria Landi Franco / Resumo: O queijo Prato é caracterizado como gordo e de média umidade, sendo o segundo mais consumido no país. Contudo, a associação da ingestão de gorduras com o desenvolvimento de doenças coronarianas e carcinogênicas tem incentivado a procura por alimentos menos calóricos e que, ao mesmo tempo, sejam tão agradáveis ao paladar quanto às versões integrais. Algumas melhorias tecnológicas foram desenvolvidas para promover bons aspectos físicos e sensoriais para queijos com baixo teor de gordura, incluindo o uso de substitutos de gordura. Nesta pesquisa, foram incorporados ao queijo Prato dois diferentes substitutos de gordura, aplicados simultaneamente, a fim de avaliar o efeito sobre a qualidade tecnológica desse queijo. Foram feitos dois processamentos dos queijos conforme 3 tratamentos: um controle, fabricado com leite integral e dois fabricados com leite padronizado a 1,5% de gordura: um queijo Prato light e outro queijo Prato light modificado, adicionado dos substitutos de gordura concentrado protéico de soro (CPS) e colágeno hidrolisado, nas concentrações de 1,0 e 0,5%, respectivamente. Durante o processo de maturação foram realizadas análises físico-químicas para a caracterização dos produtos, avaliação da proteólise, do derretimento e da textura. Os resultados obtidos para o conteúdo de gordura permitiram que os queijos fossem classificados como produtos light, por apresentarem redução maior que 25%, em relação ao conteúdo médio de gordura do queijo Prato integral. A adição dos substitutos promoveu aumento do teor de umidade e, conseqüentemente, do rendimento dos queijos. O comportamento da glicólise e da proteólise durante a maturação do queijo Prato light modificado foi próximo ao observado para o queijo Prato integral. Entretanto, não houve uma relação entre a adição dos substitutos de gordura e aumento da capacidade de derretimento... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Prato cheese is characterized as fatty and with medium moisture, it is very appreciated by consumers, being the second most consumed in the country. However, the association of fat intake with the development of coronary heart disease and cancers has prompted the search for food with fewer calories, but, at the same time, it must be as pleasing to taste as the full fat counterparts. Some alternatives were developed to improve physical and sensory characteristics in cheeses with reduced fat, including the use of fat substitutes. In this research, two different types of substitutes were incorporated into Prato cheese, to evaluate the effect on the technological quality of this cheese. The cheeses were prepared according to three treatments: a control, made with full fat milk and two made from standardized milk, a Prato light cheese and another Prato light cheese with added fat replacers: whey protein concentrate (WPC) and hydrolyzed collagen, respectively at a concentration of 1.0 and 0.5%, and repeated twice. During the ripening, the cheeses were submitted to analyses of the evaluation of proteolysis, melting and texture. The results obtained for the fat content allow the cheeses to be classified as light products, because they presented more than 25% of reduction, compared with the average fat content of a full fat Prato cheese. The addition of substitutes promoted an increase in moisture content and, consequently, in the yield of cheese; there was no influence on the acidity and proteolysis development. On the other hand, there was no relationship between the addition of fat substitutes and increasing the melting capacity and improving the texture of the Prato light cheese. Thus, further studies are needed to better understand the effect of whey protein concentrate and hydrolyzed collagen in the quality of these products, in order to assess their potential for production... (Complete abstract click electronic access below) / Mestre

Es wird gezeigt, dass mit dem Fluoreszenzmesssystem sowohl die Schichtdicke als auch die Aushärtung detektiert werden kann. Durch das Erstellen von Eichkurven ist es so möglich, vollflächig, die genaue Schichtdicke der Beschichtung im laufenden Prozess inline zu bestimmen und Abweichungen in Echtzeit entgegenzuwirken. Zudem können so Unregelmäßigkeiten bei der Aushärtung der Lacke direkt erkannt und bei unzureichender Aushärtung der Anteil von Fehlproduktionen minimiert werden. Auch bei hochvernetzten Acrylatklebstoffen konnte gezeigt werden, dass mit dem System eine genaue Analyse der inneren Festigkeit vorgenommen werden kann. Diese Klebstoffe, mit teilweise unterschiedlichem chemischen Aufbau, aber gleichem E-Modul, emittieren dasselbe Maß an Fluoreszenz. Somit konnte gezeigt werden, dass mit der Fluoreszenzmessung, unabhängig von der chemischen Struktur, gleichbleibende Intensitäten gemessen und damit der Aushärtegrad bestimmt werden kann. Zur genauen Bestimmung der Schichtdicken mit dem Fluoreszenzmesssystem ist es notwendig genaue Eichkurven für jedes einzelne System zu erstellen. Auch ist es, im Falle der Molkeprotein Beschichtungen notwendig weitere Formulierungen zu testen um eine exakte Vorhersage des Vernetzungsgrads zu gewährleisten. Durch die Ergebnisse die mit den Acrylatklebstoffen erzielt wurden stellt sich die Frage, inwieweit eine Korrelation zwischen der chemischen Struktur des untersuchten Materials und der gemessenen Fluoreszenz dabei besteht. Es sollte die Fluoreszenz von weiteren Materialien, unterschiedlicher chemischer Struktur, gemessen und überprüft werden, ob ein Zusammenhang zu deren E-Modul besteht. Außerdem sind Materialien wie z.B. Klebstoffe und Lacke auf Polyurethanbasis, deren Aushärtung erst nach mehreren Tagen oder Wochen abgeschlossen ist, interessant. Dabei stellt sich die Frage, ob Abweichungen der Aushärtung schon direkt nach der Beschichtung, durch das Fluoreszenzmesssystem, detektiert und somit Fehlproduktionen schon frühzeitig erkennt werden können. [... aus Zusammenfassung und Ausblick]

Made available in DSpace on 2014-06-11T19:29:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-04-26Bitstream added on 2014-06-13T20:20:07Z : No. of bitstreams: 1 diamantino_im_me_sjrp.pdf: 386013 bytes, checksum: b3b87690b057fd61f3bc7ef1ddfed013 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O queijo Prato é caracterizado como gordo e de média umidade, sendo o segundo mais consumido no país. Contudo, a associação da ingestão de gorduras com o desenvolvimento de doenças coronarianas e carcinogênicas tem incentivado a procura por alimentos menos calóricos e que, ao mesmo tempo, sejam tão agradáveis ao paladar quanto às versões integrais. Algumas melhorias tecnológicas foram desenvolvidas para promover bons aspectos físicos e sensoriais para queijos com baixo teor de gordura, incluindo o uso de substitutos de gordura. Nesta pesquisa, foram incorporados ao queijo Prato dois diferentes substitutos de gordura, aplicados simultaneamente, a fim de avaliar o efeito sobre a qualidade tecnológica desse queijo. Foram feitos dois processamentos dos queijos conforme 3 tratamentos: um controle, fabricado com leite integral e dois fabricados com leite padronizado a 1,5% de gordura: um queijo Prato light e outro queijo Prato light modificado, adicionado dos substitutos de gordura concentrado protéico de soro (CPS) e colágeno hidrolisado, nas concentrações de 1,0 e 0,5%, respectivamente. Durante o processo de maturação foram realizadas análises físico-químicas para a caracterização dos produtos, avaliação da proteólise, do derretimento e da textura. Os resultados obtidos para o conteúdo de gordura permitiram que os queijos fossem classificados como produtos light, por apresentarem redução maior que 25%, em relação ao conteúdo médio de gordura do queijo Prato integral. A adição dos substitutos promoveu aumento do teor de umidade e, conseqüentemente, do rendimento dos queijos. O comportamento da glicólise e da proteólise durante a maturação do queijo Prato light modificado foi próximo ao observado para o queijo Prato integral. Entretanto, não houve uma relação entre a adição dos substitutos de gordura e aumento da capacidade de derretimento... / Prato cheese is characterized as fatty and with medium moisture, it is very appreciated by consumers, being the second most consumed in the country. However, the association of fat intake with the development of coronary heart disease and cancers has prompted the search for food with fewer calories, but, at the same time, it must be as pleasing to taste as the full fat counterparts. Some alternatives were developed to improve physical and sensory characteristics in cheeses with reduced fat, including the use of fat substitutes. In this research, two different types of substitutes were incorporated into Prato cheese, to evaluate the effect on the technological quality of this cheese. The cheeses were prepared according to three treatments: a control, made with full fat milk and two made from standardized milk, a Prato light cheese and another Prato light cheese with added fat replacers: whey protein concentrate (WPC) and hydrolyzed collagen, respectively at a concentration of 1.0 and 0.5%, and repeated twice. During the ripening, the cheeses were submitted to analyses of the evaluation of proteolysis, melting and texture. The results obtained for the fat content allow the cheeses to be classified as light products, because they presented more than 25% of reduction, compared with the average fat content of a full fat Prato cheese. The addition of substitutes promoted an increase in moisture content and, consequently, in the yield of cheese; there was no influence on the acidity and proteolysis development. On the other hand, there was no relationship between the addition of fat substitutes and increasing the melting capacity and improving the texture of the Prato light cheese. Thus, further studies are needed to better understand the effect of whey protein concentrate and hydrolyzed collagen in the quality of these products, in order to assess their potential for production... (Complete abstract click electronic access below)

O objetivo do presente estudo foi estabelecer os valores de referência do proteinograma de soro lácteo por meio da técnica de eletroforese SDS-PAGE para a lactação plena e avaliar os efeitos do processo de secagem da glândula mamária, fase colostral e primeiro mês de lactação, fase de lactação, número de lactações, isolamento bacteriano e infecção pelo VCAE nas proteínas da secreção láctea de cabras da raça Saanen. Foram analisadas, entre 2007 e 2010, 545 amostras de leite provenientes de 185 cabras em diversas fases da lactação. Durante a lactação plena, baseado nos resultados dos intervalos de confiança, foram determinados os seguintes valores de referência: proteína total entre 2.940,0 e 3.050 mg/dL; proteína do soro lácteo entre 903,0 e 973,0 mg/dL; lactoferrina entre 68,0 e 77,0 mg/dL; albumina entre 88,0 e 97,0 mg/dL; imunoglobulina cadeia pesada entre 93,3 e 103,0 mg/dL; imunoglobulina cadeia leve entre 132,7 e 146,0 mg/dL; β-lactoglobulina entre 299,0 e 329,0 mg/dL e α-lactoalbumina entre 213,0 e 229,5 mg/dL. Os valores absolutos de proteína total, proteína do soro e frações protéicas aumentam durante a secagem da glândula. Antes da secagem predominavam as frações de β-Lg e α-La, a partir do 3º dia, ocorre o surgimento das novas frações e a alteração do perfil protéico sem que haja o predomínio de nenhuma fração. A fase colostral, primeiras 24 horas de lactação, determinam as maiores concentrações de proteína total, proteína do soro e frações protéicas que diminuem após as primeiras 12 horas de lactação estabilizando após o 5º dia. No colostro as imunoglobulinas são predominantes, e após o período de transição do colostro para o leite as frações β-Lg e α-La são predominantes. Nos primeiros 15 dias de lactação, devido à influência da fase colostral, observa-se que as concentrações de proteína total e proteína do soro lácteo são maiores. A partir desse momento permanecem estáveis voltando a aumentar no final da lactação. As frações protéicas do soro de leite (lactoferrina, albumina sérica, imunoglobulina de cadeia pesada, imunoglobulina de cadeia leve, β-Lg e α-La) também são máximas nos primeiros 15 dias de lactação e diminuem ao longo do período. A concentração de proteína do soro e suas frações em cabras primíparas foi menor quando comparadas com cabras pluríparas. O isolamento bacteriano não influencia as concentrações de proteína total do leite e proteína do soro lácteo de cabras, contudo a concentração de lactoferrina é maior e as concentrações de β-Lg e α-La são menores em amostras com isolamento bacteriano. O CAEV não influencia as concentrações de proteína total do leite e proteína do soro lácteo de cabras, contudo a concentração de lactoferrina é maior e a concentração de e α-La é menor em cabras sororeagentes positivas ao VCAE. / The aim of this study was to establish reference values of the whey protein through the technique of SDS-PAGE for the full lactation and to evaluate the effects of the dry period of the mammary gland, colostral phase and first month of lactation, lactation, lactation number, bacterial isolation and VCAE infection in proteins of milk secretion in Saanen goats. Were analyzed between 2007 and 2010, 545 milk samples from 185 goats at different stages of lactation. During full lactation, based on the results of the confidence intervals were determined the following reference values: total protein between 2,940.0 and 3,050 mg / dL; whey protein between 903.0 and 973.0 mg / dL; lactoferrin between 68.0 and 77.0 mg / dL, serum albumin between 88.0 and 97.0 mg /dL, immunoglobulin heavy chain between 93.3 and 103.0 mg / dL, immunoglobulin light chain between 132.7 and 146, 0 mg / dL, β-lactoglobulin between 299.0 and 329.0 mg / dL and α-lactalbumin between 213.0 and 229.5 mg / dL. The absolute values of total protein, whey protein and protein fractions increase during the dry period. Prevailed prior to dry period the fractions of β-Lg and α-La from the 3rd day, occurs the emergence of new fractions and protein profile changes without the predominance of any fraction The colostral phase, the first 24 hours of lactation, determine the highest concentrations of total protein, whey protein and protein fractions that decrease after the first 12 hours of lactation stabilized after the 5th day. Immunoglobulin in colostrum is prevalent, and after the period of transition from colostrum to milk fractions β-Lg and α-La are predominant. In the first 15 days of lactation, due to the influence of colostral phase, it is observed that the concentrations of total protein and whey protein are higher. From then remain stable before rising again in late lactation. The protein fractions of whey (lactoferrin, serum albumin, immunoglobulin heavy chain, immunoglobulin light chain, β-Lg and α-La) are also maximal in the first 15 days of lactation and decrease during the period. The concentration of whey protein and protein fractions in heifers are smaller when compared with multiparous goats. Bacteria isolation does not influence the concentrations of total protein from milk and whey protein of goats, but the concentration of lactoferrin is increased and the concentrations of β-Lg and α-La is smaller in samples with bacterial isolation. The CAEV does not influence the concentrations of total protein and whey protein in goat, but the concentration of lactoferrin is higher and concentration of α-La is less in goat positive by the CAEV.

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No. of bitstreams: 1 thallespedrosalisboa.pdf: 1465236 bytes, checksum: aaa9dd1e5c02771aa461d7ac8937e8e5 (MD5) Previous issue date: 2016-07-28 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Neste trabalho foi otimizado um procedimento de preparo de amostras com digestão ácida em forno de micro-ondas para a determinação do elemento mineral cromo por espectrometria de absorção atômica em forno de grafite (GF AAS) em amostras de suplemento alimentar do tipo whey protein, hipercalórico e protein bar. Os parâmetros instrumentais relativos à determinação de Cr por GF AAS foram otimizados, sendo selecionada a temperatura de pirólise de 1100 ºC para a análise das amostras de whey protein e hipercalórico e 1050 ºC para a análise das amostras de protein bar. Já a temperatura de atomização foi fixada em 2300 ºC para todas as amostras. Os valores de concentração de cromo, nas amostras, foram obtidos através de curva de calibração externa validada através da análise de variância e variaram de 0,403 a 0,647 µg/g para amostras de protein bar, 0,266 a 0,442 µg/g para amostras de hipercalórico e 0,224 a 1,04 µg/g para amostras de whey protein. Foi observada ainda a presença de cromo em amostras sem informações nutricionais rotuladas a respeito de enriquecimento dos suplementos com este micronutriente e, em alguns casos, em concentrações superiores ao indicado como dose diária recomendada para adultos, que é de 35 µg. A difração de raios X de pó (DRX) foi utilizada como ferramenta analítica para avaliação do estado de oxidação do cromo nas amostras de suplemento alimentar. Nos resultados obtidos foi verificada a presença de picos de difração característicos do Cr+3, sob a forma de picolinato de cromo, para os três tipos de amostras e a presença picos de difração característicos para o Cr+6, sob a forma de trióxido de cromo (VI), para as amostras de whey protein e hipercalórico. As determinações de sódio e potássio foram realizadas através do método de adição de padrão empregando como técnica analítica a espectrometria de emissão atômica em chama (F AES). As concentrações de Na variaram na faixa de 1,4 a 5,4 mg/g, 0,3 a 3,5 mg/g e 0,4 a 8,8 mg/g, enquanto que as concentrações de K variaram na faixa de 1,5 a 18,2 mg/g, 0,5 a 6,5 mg/g e 3,3 a 33,7 mg/g para as amostras de protein bar, hipercalórico e whey protein, respectivamente. Além disso, os resultados obtidos por F AES permitiram o cálculo da razão Na/K para as amostras de suplementos e pode-se considerá-las adequadas de acordo com as recomendações da OMS (Na/K ≤ 1). Finalmente, por meio de ensaios interlaboratoriais promoveu-se a comparação estatística dos resultados obtidos pelos métodos desenvolvidos com resultados obtidos por ICP-MS, garantindo a confiabilidade dos dados aqui apresentados. / In this work, a sample preparation procedure with acid digestion in a microwave oven has been optimized for the determination of chromium by graphite furnace atomic absorption spectrometry (GF AAS) in three types of food supplement samples: whey protein, hypercaloric and protein bar. The instrumental parameters for the determination of Cr by GF AAS have been optimized by setting the temperature pyrolysis at 1100 °C for the analysis of samples of whey protein and hypercaloric and 1050 ºC for the analysis of samples of protein bar, the atomization temperature was set at 2300 ºC for all samples. The chromium concentration values were obtained by external calibration curve, validated through variance analysis, and ranged from 0.403 to 0.647 µg/g for protein bar samples, from 0.266 to 0.442 µg/g for hypercaloric samples and from 0.224 to 1.04 µg/g for whey protein samples. It was also observed the presence of chromium in samples without nutritional information related to chromium enrichment, in which some concentrations were above the one stated as the recommended daily dose for adults (35 µg). The X-ray diffraction (XRD) was used as a chemical tool to evaluate the chromium oxidation state in the food supplement samples. The results showed the presence of characteristic diffraction peaks of Cr+3 in the form of chromium picolinate to the three types of samples and the presence of diffraction peaks characteristic to Cr+6 in the form of chromium trioxide (VI), for samples of whey protein and hypercaloric. Sodium and potassium determinations were performed by flame atomic emission spectrometry (F AES). For the analytes quantification it was used the standard addition method. The sodium concentrations varied in the range of 1.4 to 5.4 mg/g, 0.3 to 3.5 mg/g and 0.4 to 8.8 mg/g, while the potassium concentrations varied in the range of 1.5 to 18.2 mg/g 0.5 to 6.5 mg/g and 3.3 to 33.7 mg/g for the samples of protein bar, hypercaloric and whey protein, respectively. Besides, these results obtained by F AES allowed the calculation of the Na/K ratios for the supplement samples. The values obtained (≤ 1) suggest they can be considered appropriate according to WHO recommendations. Finally, through an inter-laboratory tests the results obtained by ICP-MS, showing a good agreement at a 95% confidence level. It ensured the reliability of the presented data and conclusion.

Es wird gezeigt, dass mit dem Fluoreszenzmesssystem sowohl die Schichtdicke als auch die Aushärtung detektiert werden kann. Durch das Erstellen von Eichkurven ist es so möglich, vollflächig, die genaue Schichtdicke der Beschichtung im laufenden Prozess inline zu bestimmen und Abweichungen in Echtzeit entgegenzuwirken. Zudem können so Unregelmäßigkeiten bei der Aushärtung der Lacke direkt erkannt und bei unzureichender Aushärtung der Anteil von Fehlproduktionen minimiert werden. Auch bei hochvernetzten Acrylatklebstoffen konnte gezeigt werden, dass mit dem System eine genaue Analyse der inneren Festigkeit vorgenommen werden kann. Diese Klebstoffe, mit teilweise unterschiedlichem chemischen Aufbau, aber gleichem E-Modul, emittieren dasselbe Maß an Fluoreszenz. Somit konnte gezeigt werden, dass mit der Fluoreszenzmessung, unabhängig von der chemischen Struktur, gleichbleibende Intensitäten gemessen und damit der Aushärtegrad bestimmt werden kann. Zur genauen Bestimmung der Schichtdicken mit dem Fluoreszenzmesssystem ist es notwendig genaue Eichkurven für jedes einzelne System zu erstellen. Auch ist es, im Falle der Molkeprotein Beschichtungen notwendig weitere Formulierungen zu testen um eine exakte Vorhersage des Vernetzungsgrads zu gewährleisten. Durch die Ergebnisse die mit den Acrylatklebstoffen erzielt wurden stellt sich die Frage, inwieweit eine Korrelation zwischen der chemischen Struktur des untersuchten Materials und der gemessenen Fluoreszenz dabei besteht. Es sollte die Fluoreszenz von weiteren Materialien, unterschiedlicher chemischer Struktur, gemessen und überprüft werden, ob ein Zusammenhang zu deren E-Modul besteht. Außerdem sind Materialien wie z.B. Klebstoffe und Lacke auf Polyurethanbasis, deren Aushärtung erst nach mehreren Tagen oder Wochen abgeschlossen ist, interessant. Dabei stellt sich die Frage, ob Abweichungen der Aushärtung schon direkt nach der Beschichtung, durch das Fluoreszenzmesssystem, detektiert und somit Fehlproduktionen schon frühzeitig erkennt werden können. [... aus Zusammenfassung und Ausblick]

<p>  </p> <p>  In this study, whey protein isolate (WPI) and high gellan gum (HAGG) were selected as natural ingredients to produce food-grade biopolymer particles for stabilizing the air-water interface. To achieve this, different mixing ratios of WPI and HAGG were employed, and heat treatment was implemented at different pH levels under the same concentration based on investigations of the pH-driven phase behavior of the WPI/HAGG complex system. The resulting WPI/HAGG complex particles were then evaluated for their ability to stabilize air-water interfaces by measuring their foaming properties.</p> <p><br></p> <p>  Foams generated using 0.1% (wt/wt) WPI/HAGG complex particles, heated at pH 5 with the mixing ratio 2:1 has demonstrated enhanced stability over a period of 30 hours compared to the WPI alone. The unique properties of these complex particles, including their smaller size (around 500nm), greater negative charge (more negative than -30 mV), and compact spherical core-shell structure, along with the higher viscosity in the continuous phase as well as the presence of small protein particles and gellan chains at the interface, collectively contribute to their superior performance as foam stabilizers. This allows for the creation of aerated food products with desirable characteristics, including product handling, enhanced texture, and prolonged shelf life in food industry.</p>