A jabuticaba é uma fruta originalmente brasileira e que começa a ser explorada comercialmente para produção de polpa congelada, geleia, licor, dentre outros produtos. O processamento da jabuticaba gera uma grande quantidade de resíduos, oriundos da casca e da semente, que normalmente são descartados em aterros, contribuindo para poluição ambiental. Todavia, esses resíduos são ótimas fontes de ingredientes funcionais, tais como antocianinas (pigmentos roxos) e elagitaninos, ambos potentes antioxidantes. Assim, o objetivo deste estudo foi extrair o pigmento do resíduo do despolpamento da jabuticaba e caracteriza-lo; estudar o processo de secagem por atomização do pigmento;caracterizar os pós obtidos, bem como sua propriedade antioxidante e estabilidade durante o armazenamento. Para tanto, a jabuticaba foidespolpada, e do resíduo (cascas e sementes) foi obtido um extrato aquoso, o qual foi caracterizado quanto ao teor de sólidos solúveis, pH, umidade, cinzas, proteínas, lipídeos, fibras, açúcares e acidez, e, em seguida, foi desidratado em spray-dryer com os agentes carreadores maltodextrina DE10 e goma arábica. Os pós obtidos foram caracterizados quanto à umidade, higroscopicidade, cor instrumental, morfologia e tamanho das partículas, teor de antocianinas, estabilidade e propriedade antioxidante pelos métodos ORAC e DPPH, estabilidade durante estocagem e isotermas de sorção. O extrato aquoso obtido apresentou 10% de sólidos solúveis totais, pH 3,54, acidez de 0,71 g ácido cítrico/100g amostra e teor de antocianinas de 79,3 mg de antocianinas/100g de amostra. Os pós obtidos com maltodextrina em condições otimizadas apresentaram retenção média de antocianinas de 77%, umidade média de 4,0%, higroscopicidade média de 34,9 g de água absorvida/100 g de pó, rendimento médio do processo de 32,1% e em média 11,5 mg/g pó de antocianinas totais. Os valores médios para a atividade antioxidante variaram de 826,9 a 266,0 µmoles equivalentes de Trolox/g pelos métodos ORAC e DPPH, respectivamente. Já para os pós obtidos com goma arábica em condições otimizadas a retenção média de antocianinas foi de 86%, umidade média de 3,9%, higroscopicidade média de 56,1 g água absorvida/100g pó, rendimento médio do processo de 35,7% e em média 14,8 mg/g pó de antocianinas totais. Os valores médios para a atividade antioxidante variaram de 227,2 a 1152,7 µmoles equivalentes de Trolox/g de pó pelos métodos DPPH e ORAC, respectivamente. Os pós obtidos apresentaram valores altos para antocianinas, fenólicos totais e atividade antioxidante, mostrando o grande potencial do resíduo do despolpamento da jabuticaba para produção de um pigmento funcional. A presença do carreador foi efetiva para manter a estabilidade do pigmento durante a estocagem e quanto maior a sua concentração, maior a estabilidade do pigmento. / The jabuticaba is originally a Brazilian fruit and begins to be exploited commercially for the production of frozen pulp, jelly, liquor, among oth er products. The processing of jabuticaba generates a lot of waste, from the peel and seeds, which are usually discarded in landfills, contributing to environmental pollution. However, these residues are good sources of functional ingredients, such as anthocyanins (purple pigments) and elagitannins, both potent antioxidants. The objective of this study was to extract the pigment from the pulping of jabuticaba\'s waste and characterized it, to study the process of spray drying the pigment; characterize the po wders, as well as its antioxidant properties and storage stability. To this aim, jabuticaba was pulped, and the residue (peel and seeds) was obtained from an aqueous extract, which was characterized as the soluble solids, pH, moisture, ash, protein, lipid, fiber, sugars and acidity, and then was dried in a spray-dryer with agents carriers of 10 maltodextrin and gum arabic. The powders were characterized for moisture, hygroscopicity, instrumental color, morphology and particle size, anthocyanins, stability and antioxidant properties by ORAC and DPPH methods and stability during storage. The aqueous extract obtained showed 10% of total soluble solids, pH 3.54, acidity 0.71 g citric acid/100g sample and anthocyanin content of 79.3 mg anthocyanin/100g sample. The powders obtained under optimized conditions with maltodextrin showed retention of 77% anthocyanins, 4.0% of humidity, hygroscopicity of 34.9 g water absorbed/100g powder, yield of the process 32.1% and on average 11.5 mg/g of anthocyanins. The mean values for the antioxidant activity ranged from 826.9 µM Trolox equivalents/g jabuticaba\'s powder to 266.0 µM Trolox equivalents/g jabuticaba\'s powder for ORAC and DPPH methods, respectively. The gum arabic powders obtained under optimized conditions showed average retention of 86% anthocyanins, 3.9% average humidity, hygroscopicity average of 56.1 g water absorbed/100g powder, average yield of 35.7% of the process and an average of 14.8 mg/g powder anthocyanins. The mean values for the antioxidant activity ranged from 1152.7 µM Trolox equivalents/g jabuticaba\'s powder to 227.2 µM Trolox equivalents/g jabuticaba\'s powder for ORAC and DPPH methods, respectively. The powders obtained showed high concentration of anthocyanins, phenolic compounds and antioxidant activity, showing the great potential of the residue of jabuticaba\'s waste for production of a functional pigment. The presence of the carrier was effective for maintaining stability of the pigment during storage and the higher the concentration, the greater the stability of the pigment

Este trabalho teve o objetivo de avaliar o efeito do uso de goma de mascar contendo 15% de xilitol, por 30 dias, em 12 indivíduos com altos níveis salivares (= 10 5 u.f.c./ml de saliva) de Estreptococos do grupo mutans (SM) sobre os níveis salivares de SM, os genótipos de S. mutans e a ocorrência de amostras xilitol-tolerantes (X R ) na saliva. Os voluntários foram instruídos a mascarem a goma por 5 minutos, 5 vezes ao dia, durante 30 dias, sem realizarem nenhuma alteração nos hábitos de higiene ou dieta. Amostras de saliva foram coletadas no início do experimento (antes do consumo da goma de mascar), 30 dias após a utilização da goma de mascar e 30 dias após a interrupção do uso da goma. Dois voluntários foram excluídos da última coleta devido ao uso de antibióticos. Os resultados mostraram que ocorreu redução acentuada nos níveis salivares de SM. A concentração média de SM no exame inicial foi de 9,8 x 10 5 ± 2,61 x 10 5 UFC/ml de saliva, enquanto este valor foi de 2,17 x 10 5 ± 1,94 x 10 5 após o consumo da goma, sendo a diferença estatisticamente significante (p < 0,05). Porém este efeito não foi duradouro, não apresentando diferença estatística 30 dias após a interrupção do consumo (3,5 x 10 5 ± 2,71 x 10 5 ), em relação aos valores iniciais. Foram identificados 17 genótipos distintos de S. mutans nas amostras salivares de 10 voluntários, que completaram as 3 etapas do estudo, pela técnica de RAPD-PCR, com o iniciador OPA-2. O ensaio de tolerância de S. mutans ao xylitol in vitro, em meio BHI e BHI /xilitol 1%, permitiu a identificação de 12 amostras X R entre 124 amostras estudadas, representantes dos 17 genótipos distintos. Amostras de S. mutans (X R ) foram identificadas nas 3 coletas, inclusive antes do consumo da goma. Foram identificadas amostras X R e X S com o mesmo genótipo por RAPD-PCR. A prevalência de amostras X R não apresentou relação direta com o uso de xilitol ou com os tipos genotípicos. Baseados nas condições do presente estudo, os resultados sugerem que o uso regular de gomas de mascar contendo 15 % de xilitol por 30 dias contribui para a redução dos níveis salivares de SM durante o período de consumo, porém esta redução não persiste após a interrupção do uso. Além disso, foi observado que o uso de xilitol não foi fator determinante na seleção in vivo de determinado genótipo X R / The aim of this study was to evaluate the effect of xylitol (15%) containing chewing gum, for 30 days , in 12 subjects with high mutans Streptococci (MS) salivary levels (= 10 5 c.f.u./ml) on Mutans streptococci (MS) salivary levels, on genotypes and detection of xilitol tolerant (X R ) strains of S. mutans . Volunteers were asked to chew one lozangle, for 5 minutes, five times per day, for 30 days with no change in their habitual diet or oral hygiene. Saliva samples were collected at baseline, 30 days after gum usage and 30 days after the interruption of the consumption. Two subjects were excluded from the last examination due to antibiotic use. The results showed a marked reduction in MS salivary levels. The average levels of MS in saliva in baseline was 9.8 x 10 5 ± 2.61 x 10 5 c.f.u./ml saliva and decreased to 2.17 x 10 5 ± 1.94 x 10 5 after 30 days of consumption. This difference was statistically significant (p< 0.05). However this effect was not long lasting, and 30 days after the interruption of consumption (3.5 x 10 5 ± 2.71 x 10 5 ) there was no statistically difference in relation to baseline data. Seventeen different genotypes were identified in MS salivary samples of 10 volunteers that completed the 3 sampling procedures, by RAPD-PCR using OPA-2 primer. The assay of xylitol tolerance of S. mutans in vitro, in BHI and BHI/1% xylitol allowed the identification of 12 X R isolates, among 124 tested strains representing all detected genotypes. X R strains were detected in all sampling steps, including at baseline, before chewing gum consumption. There were X R and X S isolates with the same genotypes by RAPD-PCR. The prevalence of X R strains did not show direct relation to consumption of xylitol neither to genotypes. Based on the conditions of the present study, the data suggested that the regular use of a chewing gum containing 15% xylitol for 30 days contributed to decrease MS salivary levels, however this decrease did not persist after the interruption of the consumption. In addition, the usage of xilitol was not a determinant to the emergence of a specific X R genotype in vivo

Neste trabalho, um polímero eletrólito derivado de goma de cajueiro graftizada com poliacrilamida (GC-g-PAM) foi desenvolvido para uso como floculante no tratamento de águas. Foi investigado o efeito da concentração de acrilamida e do iniciador persulfato de potássio, da energia de micro-ondas e de ultrassom sobre a eficiência da reação, produtividade e viscosidade intrínseca dos copolímeros GC-g-PAM. As matérias-primas e os copolímeros graftizados foram caracterizados por espectroscopia de infravermelho, ressonância magnética nuclear, análise termogravimétrica, calorimetria exploratória diferencial e espalhamento de luz dinâmico. A síntese realizada por ultrassom permitiu a obtenção de copolímeros graftizados com elevada eficiência de grafting e viscosidade intrínseca, em curto período de tempo. Os copolímeros obtidos com baixa concentração de iniciador (1,90×10−4 mol e 2,85×10−4 mol) apresentaram raio hidrodinâmico 1,5 vezes maior do que o raio da goma de cajueiro devido à graftização de cadeias longas de poliacrilamida nas cadeias da goma de cajueiro. A estrutura química dos copolímeros graftizados afetou positivamente o desempenho destes quando utilizados como floculante no processo de floculação. Os copolímeros GC-g-PAM apresentaram eficiência superior a 90% na remoção da turbidez de suspensão aquosa de caulim, usada como referência, bem como em água de abastecimento in natura. A grande vantagem dos floculantes GC-g-PAM reside no fato destes apresentarem cadeia macromolecular biodegradável e cadeias laterais menores do que a cadeia principal da poliacrilamida comercial, não biodegradável, utilizada como floculante. O uso do floculante derivado da goma de cajueiro para recuperação e purificação de águas, em detrimento do floculante sintético, visa a longo prazo diminuir o impacto ambiental causado pelo acúmulo de floculante sintético no lodo, já que esse não é biodegradável. / In this work a polymer electrolyte derived from cashew gum with polyacrylamide (GC-g-PAM) was developed for use as a flocculant in water treatment. The effect of concentration of acrylamide and potassium persulfate initiator, as well as microwave and ultrasound energy over the grafting efficiency, productivity, and intrinsic viscosity of copolymers GC-g-PAM were investigated. The raw materials and grafted copolymers were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and dynamic light scattering. The synthesis performed with ultrasound allowed the achievement of grafted copolymer with high grafting efficiency and intrinsic viscosity, in a short reaction time. The copolymers obtained at low initiator concentration (1.90×10−4 mol and 2.85×10−4 mol) presented a hydrodynamic radius 1.5 times larger than the one from cashew gum due to grafting of long chains of polyacrylamide onto cashew gum backbone. The chemical structure of grafted copolymers affected positively the performance of flocculants when they were used in flocculation processes. The turbidity removal of copolymer GC-g-PAM in kaolin suspension, used as reference, and in water treatment was higher than 90%. The great advantage of flocculants GC-g-PAM lies in the fact that they show biodegradable macromolecular chain with branches that are shorter than polyacrylamide commercial, non-biodegradable, used as a flocculant. The use of flocculant derived from cashew gum for water purification and recovery, instead of synthetic flocculant, in long term will decrease the environmental impact caused by the accumulation of synthetic flocculant in the sludge, since it is non-biodegradable.

Recheios são componentes utilizados na indústria de chocolates e de confeitos. Os recheios para chocolates podem ser elaborados com gorduras vegetais, açúcar fondant, creme de leite, amido ou com preparados de frutas contendo gomas. Nesses produtos, as gomas podem ser empregadas com a função de estabilizante, espessante ou como redutores de gordura, minimizando alterações sensoriais, de textura e de separação de fases. A goma guar vem sendo utilizada em muitos produtos alimentícios. A goma chichá é extraída de uma árvore brasileira (Sterculia striata) que pertence à mesma família da goma comercial caraia (Sterculia urens). O murici (Byrsonima verbascifolia, Rich) é um fruto brasileiro de alto valor nutricional. Assim foram elaboradas formulações alterando-se a base gordurosa, com os tipos de gordura hidrogenada, low trans, de cupuaçu e manteiga de cacau em diferentes teores (10%, 7,5% e 5% p/v). A polpa de murici (13%) e as gomas chichá e guar (0,3% m/v) foram adicionadas com a finalidade de agregar valor nutricional e estabilizar os recheios. O estudo reológico das formulações foi realizado por testes oscilatórios e rotacionais realizados em conjunto com imagens de microscopia óptica, sendo importante para avaliar os aspectos estruturais e micro estruturais dos produtos decorrente dos ingredientes utilizados, verificando-se assim diferenças de comportamento e interações entre os mesmos. Avaliações físico-químicas foram efetuadas nas formulações contendo gordura low trans + suco de laranja concentrado e gordura low trans + polpa de murici. Os resultados mostraram que a adição da polpa de murici elevou os teores de proteínas e minerais das formulações. A análise reológica apontou caráter sólido ou de gel forte para todas as amostras, pois o módulo elástico foi superior ao módulo viscoso (G\' > G\"). Verificou-se que as formulações com gordura low-trans + goma guar e gordura low trans + goma chichá apresentaram comportamento semelhante; a adição dessas gomas mostrou melhora na recuperação da estrutura inicial do sistema. Em geral, os recheios produzidos apresentaram boa estabilidade e valor nutricional agregado. / Fillings are components used in the chocolate and confectionery industry. The fillings for chocolates can be made with vegetable fats, fondant, cream, starch or fruit preparations containing gums. In these products, the gums can be employed as a stabilizer, thickener or a fat reducing, minimizing sensory, texture and phase separation. Guar gum has been used in many food products. Chichá gum is extracted from a Brazilian tree (Sterculia striata) that belongs to the same family of commercial karaya gum (Sterculia urens). Murici (Byrsonima verbascifolia, Rich) is a Brazilian fruit of high nutritional value. Thus formulations were prepared by changing the fat base with different fat types (hydrogenated fat, low-trans, cupuaçu and cocoa butter) and levels (10%, 7.5% and 5%). Murici pulp (13%), chichá and guar gum (0.3% w / v) were added in order to add nutritional value and stabilize. The rheological study of the formulations was performed by rotational and oscillatory tests in conjunction with optical microscopy images, being important to evaluate the structural and micro structural aspects of the products due to the added ingredients, thus verifying behavioral differences and interactions between them. Physical-chemical evaluations were leaded in the formulations containing low trans fat + concentrated orange juice and low trans fat + murici pulp. The results showed that the addition of murici pulp increased levels of proteins and minerals in formulations. The rheological analysis showed solid or strong gel character for all samples because the elastic modulus was higher than the viscous modulus (G\' > G\'\'). Formulations with low trans fat + guar gum and low trans fat + chichá gum showed similar behavior; addition of the gums showed better recovery of the initial structure of the system. In general, the produced fillings showed good stability and added nutritional value.

Selected food gums (hydrocolloids) were tested for their abilities to encapsulate enzymes for acclerating cheese ripening. The effect of pH and acidity on gel strength of the gums was determined. Enzyme was entrapped in k-carrageenan, gellan gum and milk fat and incorporated into cheese milk prior to cheese making. The cheese produced was tested for protein breakdown and amino acid production during ripening and textural and sensory properties of the ripened cheese were also evaluated. The findings and significance of this study and the literature review are presented. Gels were produced from alginate. Most gels showed reduced strength after treatment in solutions of either modified acidities or pH. There was, however, no significant change in gel strength between the different treatments for most of the gums. The activity of encapsulated enzyme were also investigated. Enzymes encapsulated in k-carrageenan, gellan and alginate gums retained higher activities than the other gums studied. Enzymes entrapped in agar gels had the least retention of activity. The retention of enzyme capsules produced from gellan, k-carrageenan and milk fat in cheese curd was investigated. Loss of encapsulated enzymes in cheese whey was also determined. Enzyme loss in the whey ranged from 5.6 to 17.9% with the highest losses observed with milk fat and the least with gellan gum capsules. Most of the cheeses treated with enzyme capsules showed higher levels of amino acid within two weeks than control cheese. After two weeks, all experimental cheeses showed higher production of amino acids than the control cheese. The addition of enzyme capsule to cheese did lead to a higher growth level of microorganisms. The experimental cheese exhibited lower score than the control cheese for most textural properties. The experimental cheeses were not significantly different in flavour and aroma from the control cheese. K-carrageenan treated cheeses were recorded as having the highest score for bitter after taste. Except for those cheeses treated with k-carrageenan capsules, the overall acceptability for the trial cheeses were not significantly different from that of 6 month old untreated cheese. / Master of Science (Hons)

This study considered the influence of exotic shrubs on birds in urban patches of Yellow Box- Blakely's Red Gum (E. melliodora-E. blakelyi) woodlands in the Australian Capital Territory, Canberra. The aim of this research was to identify native and exotic birds that have their abundance influenced by exotic shrubs. The purpose of this work was to provide more information to managers of this woodland about the potential impacts of weed control on birds living in woodland reserves adjacent to suburban areas. Birds were sampled between 1996 and 1998 using the twenty minute area-search method to derive estimates of bird abundance. Around 680 twenty minute area-searches were completed, with 665 of these undertaken at 12 two hectare plots with varying levels of exotic shrub cover over a period of ten months. The abundance of birds for each of the ten months sampled were compared by pooling sites into four classes of exotic shrub cover. Classes of exotic shrub cover were nil, light, moderate and dense. Seasonal inferences were drawn from non-parametric analysis of variance. Non-parametric measures of association were used to test for correlation between the mean abundance of bird species at different woodland sites and percentage foliage estimates of exotic shrub cover. Percentage foliage estimates of native shrub cover were included in tests for correlation between bird abundance and exotic shrub cover by applying partial measures of association. To support statistical information, observations of birds in exotic shrub cover were also recorded. In one woodland site birds were sampled before and after the removal of exotic shrub cover. No statistical tests were applied to these samples because of a lack of replication; however, descriptive graphs of the abundance of selected birds following weed control are presented. To investigate the effect that exotic shrub invasion may have on the composition of bird assemblages in woodland cluster analysis and ordination of the 12 sites using the mean abundance of the 75 species recorded between July 1997 and June 1998 were also undertaken. The presence of exotic shrub cover in E. melliodora-E. blakelyi woodland in Canberra was found to have differential effects on bird abundance. Wrens, finches, thornbills, whistlers and pigeons were more abundant in woodland sites where exotic shrubs were present when compared to sites with no or little exotic shrub cover. Fruit-eating birds, such as Silvereyes (Zosterops lateralis), Pied Currawong (Strepera graculina) and Crimson Rosella (Platycercus elegans), were more abundant in woodland with exotic shrubs in winter and autumn when these shrubs provided food in the form of berries. The abundance of fruit-eating birds, and wrens and finches was reduced in a single woodland site following the removal of most of the exotic shrub cover. The Common Blackbird (Turdus merula) was the only exotic bird which showed a strong association with exotic shrubs in woodland, while the Laughing Kookaburra (Dacelo novaeguineae) was negatively correlated with exotic shrub cover, possibly because prey is harder to detect and capture in woodland with a shrubby understorey. Cluster analysis and ordination of the 12 woodland sites did not group sites into the four experimental classes used to undertake analysis of variance. Multivariate analysis, however, did reveal that seasonal peaks in the abundance of fruit eating birds affected the composition of bird assemblages by increasing the mean abundance of these birds in densely invaded sites. Similarly, structural differences in the understorey resulted in some birds being more abundant in woodland sites invaded by exotic shrubs when compared to sites lacking a shrubby understorey. The distance between some sites confirmed this stark difference in bird life when plotted in three dimensions. The results of this study suggest that exotic shrubs add food and structural complexity to woodland habitat. Benefits of structural complexity for small native birds in woodland include nest sites and protection from predators. These benefits may operate at certain thresholds of invasion, as the woodland site with the densest level of exotic shrub invasion showed a slight decrease in the number of wrens and finches. Adverse impacts from exotic shrub invasion may include reduced open ground in which to forage and loss of floristic diversity in the understorey. In effect, exotic shrubs add and remove resources in woodland habitat, benefiting some bird species and limiting others. These findings suggest that the removal of exotic shrub cover in woodland located in urban landscapes simplifies the structural complexity of the understorey, reducing the quality of habitat for some birds. Thus, adverse impacts on biodiversity arising from the invasion of exotic shrubs in woodland need to be considered against the important role that a diverse bird population has in maintaining ecosystem function.

Xylitol, classified as a natural sugar substitute, has for about 35 years been known as an agent that may act against caries. The mechanism of action; how it inhibits mutans streptococci (MS) and the clinical dose-response relationship are not however fully investigated. The general aim of the investigations was to evaluate the effect of xylitol on oral ecology in children and adolescents. A series of experimental and controlled clinical trials were performed in which samples of saliva and plaque was collected and analysed with respect to xylitol content, pH, microbial composition and lactic acid production. In paper I, significantly reduced proportions of xylitol-sensitive MS in saliva were demonstrated after 18 weeks of regular use of two dose regimens of xylitol-containing tablets (1.7g and 3.4g xylitol/day) but the acidogenicity in dental plaque was not affected. In paper II, the effect on interdental plaque-pH of two different single dose intakes (2.0g and 6.0g) of xylitol was evaluated. The higher xylitol dose counteracted the pH-drop significantly (p&lt;0.05) when the chewing was followed by a sucrose rinse while the lower dose did not differ from the control. In paper III, the xylitol concentrations in saliva after use of different common xylitol-containing products (0.1g-1.3g) were investigated. Statistically significant elevations of salivary xylitol levels were demonstrated for all products during the first 8-16 min when compared with baseline (p&lt;0.05) but the individual variation was considerable. In samples of supragingival dental plaque, a high dose rinse (6.0g) increased the xylitol concentrations for a longer period (&gt;30 min) than a low dose rinse (2.0g). In paper IV, it was demonstrated that 6.0g of xylitol in chewing gums, every day in 4 weeks, gave significantly less visible plaque and a significantly reduced sucrose-induced lactic acid formation (p&lt;0.05) in saliva. Furthermore, the proportion of MS decreased significantly (p&lt;0.05) compared to baseline. In paper V, the salivary uptake of [14C]-xylitol was compared with a specific assay determining xylitol-sensitive MS and a fair positive correlation (p&lt;0.05) between the two assays was found. In a controlled trial, the proportions of MS and the salivary xylitol uptake decreased significantly (p&lt;0.05) in the xylitol gum test group after 4 weeks compared to baseline which was in contrast to the control gum group. No serious adverse effects were reported in any of the investigations. The main conclusions from this thesis were: a) various xylitol-containing products increased the xylitol levels in saliva and plaque, b) 6.0g of xylitol could counteract the interdental pH-drop after sugar consumption and reduce lactic acid formation in saliva c) a daily dose of 6.0g xylitol reduced the amount of visible plaque and altered the salivary microbial composition, d) a transient shift of MS strains in saliva was demonstrated during periods of regular intake of xylitol products but no long-term impact was found after its termination. The relatively high amount of xylitol needed for a beneficial effect on the oral ecology calls for a further development of effective and safe routes for administration.

The objective of this study was to determine the effects of different gums and their combination on quality and staling of breads baked in different ovens. In the first part of the study, the effects of gums (xanthan, guar, k-carrageenan, hydroxypropyl methylcellulose, locust bean gum and their blends) on quality of breads baked in infrared-microwave combination and conventional ovens were investigated. In addition, macro and micro-structure, dielectric and thermal properties and acrylamide content of breads were studied. Xanthan-guar blend addition improved bread quality with increasing specific volume and porosity values and decreasing hardness values of samples. More homogeneous closed-cell structure for conventionally baked control breads and channel formed cell structure for breads baked in infraredmicrowave combination oven were observed. Dielectric properties of breads were found to be a function of gum type. No acrylamide was formed in microwave baked breads. Breads baked in infrared-microwave combination oven had similar acrylamide content with conventionally baked ones. The second part of the study focused on staling. The hardness, retrogradation enthalpy, set back viscosity, FTIR outputs and crystallinity values of microwave-baked samples were found to be the highest. Infraredmicrowave combination heating made it possible to produce breads with similar staling degrees as conventionally baked ones and reduced the conventional baking time of breads by about 39%. Addition of xanthan-guar blend decreased hardness, retrogradation enthalpy and crystallinity values of breads. According to hardness data, in the presence of xanthan-guar blend staling of breads baked in all types of ovens was delayed for 1 day.

The main objective of this study was to design gluten free rice cakes containing different gums and an emulsifier for baking in infrared (IR)-microwave combination oven. In the first part of the study, the effects of different gums (xanthan, guar, xanthan-guar blend, &amp / #954 / -carrageenan, locust bean, hydroxypropyl methylcellulose (HPMC) and xanthan-&amp / #954 / -carrageenan blend) and emulsifier blend (PurawaveTM) on physical properties of cake batters were investigated. In the second part of the study, weight loss, specific volume and texture of the cakes baked in different ovens were determined. Macro and micro-structures of the cakes were investigated both qualitatively and quantitatively by using image analysis and Scanning Electron Microscopy (SEM). In the last part of the study, Response Surface Methodology (RSM) was used to optimize IR-microwave baking conditions and formulation of the cakes. Power law and Casson models were suitable to explain the rheological properties. Xanthan and xanthan-guar gum blends resulted in higher apparent viscosities as compared to other gums. Gum types affected the dielectric properties and gelatinization enthalpies of cake batter. Emulsifier addition increased the volume and porosity but decreased the firmness of the cakes baked in IR-microwave combination oven. More porous cakes were obtained when xanthan and xanthan-guar gum blend were used. Baking method was found to be important in affecting porosity, pore size distribution and microstructure of the cakes. The highest quality gluten-free rice cakes were obtained when the formulation contained xanthan gum and 5.38% emulsifier and baked using 40% microwave power, 60% halogen lamp power for 7 min in IR-microwave combination oven. In addition, baking time was reduced by 76.7% as compared to conventional baking.

A better understanding of how dietary fibres impact the bioavailability of fat-soluble nutrients and nutraceuticals is required. The purpose of this research was to determine the influence of guar gum (GG) on the transfer processes impacting beta-carotene (BC) bioaccessibility (transfer to the aqueous phase) from an oil-in-water emulsion using an in vitro model simulating gastric and duodenal digestion. Canola oil emulsions (1.5 % soy protein isolate, 10 % canola oil and 0.1 % all trans BC, D4,3~160 nm) were prepared by microfluidization (40 MPa, 4 passes) and exposed, in the presence of 0.0, 1.0, 1.5, 2.0, or 4.0 % GG, to conditions representative of the stomach and duodenum in the fed state. Lipolysis, BC bioaccessibility, digestate apparent viscosities, droplet size, and bile acid (BA) binding were studied. With increasing concentration of GG, digestate viscosity was increased and lipolysis and bioaccessibility were decreased (P<0.05). Peak lipolysis was 56.2% vs. 21.6% for emulsions containing 0.0 % vs. 4.0 % GG, respectively. BC bioaccessibility was also lower in the presence of GG (i.e. 29.7 vs. 6.98 % for 0.0 vs. 4.0 % GG respectively). Thus, the presence of GG impacted digestive processes central to BC absorption. The impact of GG may be related to increased digestate viscosity entrapping mixed micelles or BAs and decreasing diffusion leading to decreased lipolysis and BC bioaccessibility. / NSERC, CFI