Doctor of Philosophy / Food Science Institute / J. Scott Smith / Advanced glycation endproducts (AGEs) are formed in many cooked meat products via Maillard browning reactions. Current research suggests consumption of these compounds may be a contributor to chronic diseases such as diabetes and heart diseases. Thus, information on the prevalence and inhibition of these compounds in food is desirable. The first objective was to determine the AGE content, as determined as N[superscript]ε-carboxymethyllysine (CML) level, in cooked meat and fish prepared by general cooking methods recommended by U.S. Department of Agriculture, Food Safety and Inspection Service (USDA-FSIS). We found AGE was detected in all the cooked samples, but the levels depended on the different cooking conditions. Broiling and frying at higher cooking temperatures produced higher levels of CML and broiled beef contained the highest CML content (21.84 μg/g). However, the baked salmon (8.59 μg/g) and baked tilapia (9.72 μg/g) contained less CML as compared to the other samples. In order to investigate the inhibitory effect of selected natural antioxidant on AGEs formation in cooked meat, four cereal brans, wheat (Jagger, JA), triticale (Spring Triticale, ST; Thundercale, TH), and Rye (RY) bran were added to beef patties before cooking. RY (42.0% inhibition), ST (27.5% inhibition), and TH (21.4% inhibition) brans significantly decreased CML formation compared with the control. The inhibition of CML was correlated to the water-holding activity (WHC) of the samples, and the radical scavenging activity of the brans. The effect of cereal bran extracts (JA, ST, TH, and RY), was studied in a bovine serum albumin and glucose (BSA-GLU) model system. The ST extract significantly (P <0.05) inhibited CML formation compared to the control group. ST particularly contained vanillic acid (VA), chlorogenic acid (CHA), gentisic acid (GEA), and ferulic acid (FA), where GEA and CHA mitigated CML with an average percentage decrease of 29.6% for CHA and 51.1% for GEA. It therefore may be useful in preventing AGEs formation by using ST bran as a food addictive, which contains abundant phenolic acids. In summary, current dietary AGEs database will provide important information for use in estimating AGEs exposure, and also these data demonstrate that a significantly reduced intake of dietary AGEs can be achieved by low heat AGE cooking methods such as baking, which can be used at home or in the meat industry. Cereal bran addition to meat products may reduce formation of AGEs that is a desired attribute for the processed meat products industry.

Enzymes and subcritical water can be used for the extraction of hemicelluloses from cereal by-products, making the processes eco-friendly. The polysaccharides extracted from cereal by-products can be used as matrices for development of materials for various applications. This includes bio-based materials such as films and hydrogels, which offer alternatives to existing materials produced from petrochemicals. The polymeric structure of cereal hemicelluloses contains functional groups which enable the modification of their structure by cross-linking, resulting in the formation of hydrogels. This project aims to use subcritical water extraction (SWE) to extract arabinoxylans (AXs) from corn and rye bran meanwhile the enzymatic treatment is done for purifying the samples during both pre- and post-treatment. AXs were further crosslinked by enzyme (laccase) for hydrogel preparation. During the whole project, the characterization included moisture and yield determination, starch and protein content which were tested using a spectrophotometer, monosaccharide content was analyzed by high performance anion exchange chromatography followed by pulsed amperometric detection (HPAEC-PAD) and phenolic acid content was quantified by high performance liquid chromatography (HPLC). The pretreatment for destarching and SWE process was successful. The result showed that arabinoxylans form corn bran were having higher content of arabino substituents, arabino toxylans ratio and ferulic acid content than rye samples. The enzymatic crosslinking could form strong gels in the condition that the AXs had high ferulic acid content. In terms of forming strong hydrogels or to improving the properties of AXs gel, the pre- and post-treatment should be optimized to increase the purity of the extracted feruloylated AX content. / Enzymer och subkritiskt vatten kan användas för extraktion av hemicellulosa från spannmålsbiprodukter, vilket gör extraktionen miljövänlig. Polysackariderna extraherade från spannmålsprodukter kan användas som matriser för utveckling av material för diverse applikationer. Detta inkluderar biobaserade material som filmer och hydrogeler, där petrokemikalier kan ersättas som råvara. Den polymera strukturen hos spannmålshemicelluloser innehåller funktionella grupper som möjliggör formation av tvärbindningar vilket resulterar i bildandet av hydrogeler. Syftet med detta projekt är extraktion av arbinoxylaner (AXs) från majs och rågkli genom att använda subkritiskt vatten-extraktion (SWE) där rening under för- och efterbehandling utförs enzymatiskt. AX modifierades därefter enzymatiskt (laccas) med tvärbindningar för hydrogelframställning. Under hela projektet karakteriserades hydrogelen utifrån fuktinnehåll, bestämmelse av utbyte, stärkelse och proteininnehåll som testades med en spektrofotometer, monosackaridhalten analyserades med högpresterande anjonsutbyteskromatografi följt avpuls-amperometrisk detektion (HPAEC-PAD), samt kvantifierades fenolsyrahalten med högupplöst vätskekromatografi (HPLC). Resultatet visade att arabinoxylaner från majskli hade högre innehåll av arabinosubstituenter, där förhållandet mellan arabino och xylans, samt arabino och ferulsyra innehållet var högre än för rågproverna. Den enzymatiska tvärbindningen kunde bilda starka geler i det tillståndet där AX hade en hög ferulsyrahalt. När det gäller att bilda starka hydrogeler eller att förbättra egenskaperna hos AXs-gel, bör för-och efterbehandlingen optimeras för att öka renheten fördet extraherade feruloylerade AX-innehållet.

With the advent of industrialization and food processing techniques the sizes of the cereal bran have been drastically reduced. In my thesis, I have tested the effect, if any, of wheat bran and maize bran particle size, in vitro, on the gut microbiota community structure by 16S rRNA sequencing and their function, by Short chain fatty acids (acetate, propionate, butyrate) production. In turn, we also linked the microbiota and SCFA differences to different chemical composition amongst variously sized fractions of wheat and maize bran.

Dietary fibers can interfere in the bioavailability of mineral elements both negatively and positively. This has been the subject of several researches because there is a great interest in essential minerals; also, some studies have been done regarding toxic elements such as cadmium (Cd). Environmental contamination with Cd and its consequent interference in the food chain can cause serious problems in humans and animals affecting several organs in general, and this can become even worse when exposure takes place during growth. Fiber-rich supplements are employed by people that have low levels of fiber in the diet. On the other hand, multimixtures (MMs) are low-cost food supplements with different compositions that are used to improve the nutritional conditions of children. These supplements are normally rich in fibers and mineral elements. The objective of this study was to evaluate the effect of MMs and other food products rich in dietary fibers on the absorption of mineral elements and on Cd absorption, accumulation, and toxicity in growing rats. Three independent experiments were conducted. In the first experiment, MMs, used as supplements at a 5% proportion in diets, increased apparent absolute absorption of phosphorus, magnesium and manganese, proportionally to its level of dietary fiber, but did not interfere in calcium or copper absorption. This suggests that these supplements can be a source of some minerals in the diet, and similar proportions to those employed in this study did not diminish calcium and copper absorption. In the second experiment, one MM, rich in fibers and essential minerals did not diminish either Cd accumulation or toxicity when this metal was employed at 25 mg/kg in the diet, but MM diminished Cd accumulation in the kidneys when it was employed at 5 mg/kg in the diet. This latter Cd level is similar to human exposure in some contaminated areas, which suggests that MM may contribute to diminish Cd toxicity in polluted areas. In the third experiment, when flaxseed and bran wheat were compared to purified cellulose, it was observed that flaxseed, which has a higher proportion of soluble fiber, increased Cd accumulation in the liver and kidneys of growing rats in comparison to the other two fiber sources, which have basically insoluble fiber. These results indicate that foods with a higher proportion of soluble fiber can increase Cd body retention, suggesting that one should be careful when ingesting these foods in Cd contaminated areas. Flaxseed and bran wheat, used as sources of dietary fiber for rats exposed do Cd, decreased apparent absorption of Ca and P and increased apparent absorption of Mg in comparison to purified cellulose, which might be attributed to an interaction of Cd and phytate present in these fiber sources. Results of the present study show that MMs can be source of some essential mineral, besides reducing renal Cd accumulation, after exposure to low Cd doses. It was also observed that different sources of fiber may differentially affect the retention of toxic metals like Cd, and one should be careful when using foodstuffs rich in soluble fiber, like flaxseed, which can increase Cd retention. / As fibras alimentares (FA) podem interferir na biodisponibilidade de elementos minerais tanto negativa quanto positivamente. Este tem sido um assunto de diversas pesquisas e grande interesse em relação aos minerais essenciais e alguns estudos também têm sido feitos em relação aos elementos tóxicos como o cádmio (Cd). A contaminação ambiental com Cd e sua conseqüente entrada na cadeia alimentar pode levar a graves problemas no homem e nos animais em geral, afetando vários órgãos, o que pode ser mais grave quando a exposição se dá durante a fase de crescimento. Suplementos ricos em fibra são utilizados por parte da população em face da falta deste constituinte em suas dietas. Por outro lado, as multimisturas (MMs) são suplementos alimentares de composição variável e baixo custo, utilizados para melhorar o estado nutricional de crianças, sendo que estes suplementos são normalmente ricos em fibra e também em elementos minerais. O objetivo deste trabalho foi avaliar o efeito de MMs e outros produtos alimentícios ricos em FA sobre a absorção de elementos minerais e sobre a absorção, acumulação e toxicidade do Cd, em ratos em crescimento. Foram conduzidos três experimentos independentes. No primeiro experimento as multimisturas, usadas como suplementos na proporção de 5% da dieta, aumentaram a absorção absoluta aparente de fósforo, magnésio e manganês, proporcionalmente ao seu teor de fibra alimentar, não chegando a interferir na absorção de cálcio e cobre, o que sugere que estes suplementos podem ser fonte de alguns minerais na dieta e, em proporções semelhantes àquela utilizada neste estudo, não reduziriam a absorção de cálcio ou cobre. Num segundo estudo, uma MM, rica em fibra e em minerais essenciais, não reduziu a acumulação nem a toxicidade do Cd quando este foi utilizado na dose de 25 mg/kg de dieta, mas reduziu a acumulação renal do metal quando este foi utilizado na dose de 5 mg/kg de dieta, a qual é compatível com a exposição humana em algumas áreas contaminadas, sugerindo que a multimistura poderia contribuir para reduzir a toxicidade do Cd em zonas de contaminação ainda inevitável. No terceiro experimento, em que se comparou a linhaça e o farelo de trigo com a celulose purificada, observou-se que a linhaça, que contêm maior proporção de fibra solúvel, aumentou a quantidade de Cd retido no fígado e rins dos ratos em crescimento em comparação com as outras duas fontes, que contêm predominantemente fibra insolúvel. Estes resultados indicam que alimentos com maior proporção de fibra solúvel podem aumentar a deposição corporal de Cd, sugerindo que deve haver cuidado na ingestão dos mesmos em regiões contaminadas com Cd. A linhaça e o farelo de trigo, usados como fonte de fibra alimentar para os ratos expostos ao Cd, reduziram a absorção aparente do cálcio e do fósforo e aumentaram a absorção aparente de magnésio em comparação com a celulose, o que poderia ser atribuído a uma interação do Cd com o fitato presente naquelas fontes de fibra. Os resultados deste trabalho mostram que as MMs podem ser fonte de alguns minerais essenciais, além de reduzir a acumulação renal de cádmio, após exposição a baixas doses deste metal. Também observou-se que diferentes fontes de fibra podem interferir de forma diversa na retenção de minerais tóxicos como o Cd, devendo-se ter cuidado com fontes ricas em fibras solúveis, como a linhaça, que podem aumentar a retenção do metal.