Hubbard Foods Limited of Auckland makes a variety of oats-based value-added products. In the preparation of a range of products at Hubbard Foods, technical staff has become aware of a bitterness problem that sporadically appears in toasted oats. Toasting involves dry heating to about 150°C resulting in the golden colour and flavour development necessary for range of products. Bitterness development has been described in the literature, but Hubbard staff is necessarily focussed on production issues, rather than on a sporadic problem seemingly outside the scope of production variables. The author of this thesis set out to identify the cause and suggest a remedy. Prior research with oats has shown that bitterness and associated off-flavours are linked to the accumulation of free fatty acids, their volatile oxidation products, and possibly amino acids and certain phenols. Oats are distinguished from related grains by their high relative fat content, about seven percent, and an associated very active lipase. The free fatty acids stem from the lipase activity that should be, but may not be, inactivated at source in Australia. This is achieved in the milling process by physical disruption and moist heating to a temperature at which the enzyme is denatured. However, residual lipase activity may adversely affect oats quality during time in storage and transit. A number of analytical methods for cereals were adapted to match the constraints of time and resources. These methods were for colour, moisture, peroxidase activity, p-anisidine, and fat and free fatty acids content, composition of fatty acids, total phenols, volatiles, and bitterness as perceived by an analytical sensory panel of four people. Determination of lipase activity is very expensive, so peroxidase activity is commercially used as an indicator. If the latter is inactive, the former will necessarily be also inactive. The designed methods were first applied to 17 oats lots passing through the Hubbard environment, where 14 were paired raw and toasted. The values of moisture, fat content, free fatty acids content and total phenols were within the normal limits expected for commercial lots of oats compared with the previous studies. Not much variation was observed among the 17 oats lots, with the exception of lot DWHE25. Lot DWHE25 was a faulty product, which had high moisture content, high free fatty acids content, and tasted very bitter. The results suggested that moisture content, free fatty acids and bitterness were usually correlated. In spite of the differences encountered and the clues provided by extremes, the data generated from Hubbard oats lots did not provide enough variation in quality to lead to a definitive chemical model of bitter flavour development. But perhaps crucially, it was found that most samples as received from Hubbard Foods were peroxidase-active which conflicted with the results reported on specification sheets prepared by the oats supplier. These specifications accompanied each lot delivered to Hubbard Foods. Therefore, the supplier’s method was examined and was found to be deficient in one critically important respect. Their method omitted the key reactant hydrogen peroxide. Therefore, it is possible that the lipase was active in many of the samples. Therefore, some experiments were conducted where raw oats, from Hubbard Foods and a supermarket, were treated with water additions and stored for a period to examine the effect of moisture content on the quality and flavour deterioration on subsequent storage. Water-treated oats were toasted to simulate a typical Hubbard process, yielding a total of 58 samples with carrying moisture contents. The data set was statistically analysed to identify the cause of bitterness and the means of its control. The free fatty acids content, volatile compounds particularly hexanal, and total phenols increased with moisture content and storage time. The correlations between chemical analysis and sensory test indicated that free fatty acids positively correlated with bitterness (r = 0.71), and hexanal was also positively correlated. Total phenols did not appear to correlate with bitterness. Oats lots with high peroxidase activity tended to have the poorest quality, strongly implicating residual lipase activity as the critical factor. There were no important interactions between water addition and toasting for most of the experiments. Therefore, it seems likely that the toasting procedures at Hubbard Foods are not responsible for bitterness formation. The cause(s) of bitterness is certainly at source, with a faulty peroxidase test strongly implicated.

Hubbard Foods Limited of Auckland makes a variety of oats-based value-added products. In the preparation of a range of products at Hubbard Foods, technical staff has become aware of a bitterness problem that sporadically appears in toasted oats. Toasting involves dry heating to about 150°C resulting in the golden colour and flavour development necessary for range of products. Bitterness development has been described in the literature, but Hubbard staff is necessarily focussed on production issues, rather than on a sporadic problem seemingly outside the scope of production variables. The author of this thesis set out to identify the cause and suggest a remedy. Prior research with oats has shown that bitterness and associated off-flavours are linked to the accumulation of free fatty acids, their volatile oxidation products, and possibly amino acids and certain phenols. Oats are distinguished from related grains by their high relative fat content, about seven percent, and an associated very active lipase. The free fatty acids stem from the lipase activity that should be, but may not be, inactivated at source in Australia. This is achieved in the milling process by physical disruption and moist heating to a temperature at which the enzyme is denatured. However, residual lipase activity may adversely affect oats quality during time in storage and transit. A number of analytical methods for cereals were adapted to match the constraints of time and resources. These methods were for colour, moisture, peroxidase activity, p-anisidine, and fat and free fatty acids content, composition of fatty acids, total phenols, volatiles, and bitterness as perceived by an analytical sensory panel of four people. Determination of lipase activity is very expensive, so peroxidase activity is commercially used as an indicator. If the latter is inactive, the former will necessarily be also inactive. The designed methods were first applied to 17 oats lots passing through the Hubbard environment, where 14 were paired raw and toasted. The values of moisture, fat content, free fatty acids content and total phenols were within the normal limits expected for commercial lots of oats compared with the previous studies. Not much variation was observed among the 17 oats lots, with the exception of lot DWHE25. Lot DWHE25 was a faulty product, which had high moisture content, high free fatty acids content, and tasted very bitter. The results suggested that moisture content, free fatty acids and bitterness were usually correlated. In spite of the differences encountered and the clues provided by extremes, the data generated from Hubbard oats lots did not provide enough variation in quality to lead to a definitive chemical model of bitter flavour development. But perhaps crucially, it was found that most samples as received from Hubbard Foods were peroxidase-active which conflicted with the results reported on specification sheets prepared by the oats supplier. These specifications accompanied each lot delivered to Hubbard Foods. Therefore, the supplier’s method was examined and was found to be deficient in one critically important respect. Their method omitted the key reactant hydrogen peroxide. Therefore, it is possible that the lipase was active in many of the samples. Therefore, some experiments were conducted where raw oats, from Hubbard Foods and a supermarket, were treated with water additions and stored for a period to examine the effect of moisture content on the quality and flavour deterioration on subsequent storage. Water-treated oats were toasted to simulate a typical Hubbard process, yielding a total of 58 samples with carrying moisture contents. The data set was statistically analysed to identify the cause of bitterness and the means of its control. The free fatty acids content, volatile compounds particularly hexanal, and total phenols increased with moisture content and storage time. The correlations between chemical analysis and sensory test indicated that free fatty acids positively correlated with bitterness (r = 0.71), and hexanal was also positively correlated. Total phenols did not appear to correlate with bitterness. Oats lots with high peroxidase activity tended to have the poorest quality, strongly implicating residual lipase activity as the critical factor. There were no important interactions between water addition and toasting for most of the experiments. Therefore, it seems likely that the toasting procedures at Hubbard Foods are not responsible for bitterness formation. The cause(s) of bitterness is certainly at source, with a faulty peroxidase test strongly implicated.

A cachaça é uma bebida típica brasileira, majoritariamente consumida ao natural. Sua qualidade pode ser melhorada pelo envelhecimento. No Brasil, o envelhecimento é tradicionalmente feito pelo armazenamento do destilado em toneis de madeira de lei nacional. O uso de toneis demanda alto custo inicial e longo prazo de imobilização do produto e capital. Alternativas de armazenamento têm sido procuradas, porém sem solução para o envelhecimento. A possibilidade do uso de fragmentos de carvalho para a maturação da cachaça pode proporcionar um maior campo de tipicidades para a bebida. O objetivo deste trabalho foi estudar congêneres voláteis e de maturação em cachaça macerada com fragmentos de madeiras de carvalho proveniente de diferentes florestas francesas (Allier, Vosges e Nièvre) e com diferentes intensidades de tosta (fraca, média e forte). Os congêneres voláteis (acetaldeído, acetato de etila, metanol, 2-butanol, 1-propanol, isobutanol, 1- butanol, álcool isoamílico e ácido acético) foram detectados e quantificados por cromatografia gasosa com detector de ionização de chama (GC-FID) e os congêneres de maturação (ácido gálico, 5-hidroximetilfurfural, furfural, ácido vanílico, ácido siríngico, vanilina, siringaldeído, coniferaldeído e sinapaldeído) foram analisados por cromatografia líquida de alta eficiência (HPLC/CLAE). Testes sensoriais foram realizados para a verificação da aceitação das amostras pelos consumidores quanto aos parâmetros de cor, aroma, sabor e impressão global. A concentração de congêneres voláteis não foi influenciada pelos tratamentos. A presença de congêneres de maturação permitiu concluir que não há contestação na capacidade de ceder compostos entre as madeiras das diferentes florestas, porém a peculiaridade de cada uma delas é destacada quando se analisa a predominância dos compostos de interesse. Em virtude da ampla concentração de congêneres de maturação presente em madeiras de Vosges e de Allier com tosta forte, pudemos supor maior complexidade química na cachaça macerada nessas condições. Seria ainda possível a variação da cachaça macerada mediante uso de fragmentos de carvalho de origens distintas combinando com diferentes intensidades de tosta. Os testes sensoriais apontaram elevada aceitação quanto aos atributos analisados, porém não houve efeito perceptível entre as diferentes madeiras e tostas. O uso de lascas de madeira para a maceração de bebidas não é reconhecido como processo de envelhecimento, podendo ser confundido com ato fraudulento. O presente estudo representa um embasamento teórico-prático para a possível aplicação da metodologia, porém ressalta a importância do estudo comparativo entre o envelhecimento em toneis e por interação de lascas de madeira, visando identificar similaridades e diferenças entre as metodologias e verificar a viabilidade de sua aplicação. / Cachaça is a typical Brazilian spirit, consumed mostly natural. Its quality may be improved by aging. In Brazil the aging process is traditionally done by keeping the spirit in barrels made of national hardwood. The use of barrels demand high initial cost and long-term of immobilization of product and capital. Storage alternatives have been sought, but without solution for aging so far. The possibility of using oak fragments for cachaça maturation may provide a wider field of specificities to the spirit. The objective of this research was to study volatile and maturation congeners in cachaça macerated with fragments of oak wood from different French forests (Allier, Vosges and Nièvre) and with different intensities of toasting (low, medium and high). The volatile congeners (acetaldehyde, ethyl acetate, methanol, 2- butanol, 1-propanol, 1-butanol, isobutanol, isoamyl alcohol and acetic acid) were detected and quantified by gas chromatography with flame ionization detector (GCFID) and the maturation congeners (gallic acid, 5-hydroxymethylfurfural, furfural, vanillic acid, syringic acid, vanillin, syringaldehyde, coniferaldehyde and synapaldehyde) were measured by high performance liquid chromatography (HPLC). Sensory tests were performed to verify consumer´s acceptance concerning the parameters of color, aroma, flavor and global acceptation. The concentration of volatile congeners was not influenced by the treatments. The presence of maturation congeners indicated the ability of the different wood fragments in supplying compounds to the spirit. Nevertheless the peculiarity of each one is highlighted when the compounds predominance is investigated. Due to the high concentration of maturation congeners supplied by Allier and Vosges woods at high toast, we could assume more chemistry complexity for the cachaças macerated in these conditions. It could also be possible modeling cachaça based on maceration with oak fragments from different origins combined with different intensities of toasting. Sensory tests showed high acceptance on the attributes evaluated, but there was no considerable effect between the different woods and toastings. The use of wood fragments to cachaça maceration is not allowed by the Brazilian laws as an aging process, and might be considered a fraudulent act. This study represents a theoretical and practical basis for a possible application of the methodology. It stresses the importance of a further comparative study concerning aging in barrel and by interaction of wood fragments in order to identify similarities and differences between the methodologies and verify the feasibility of its implementation.

A cachaça é uma bebida típica brasileira, majoritariamente consumida ao natural. Sua qualidade pode ser melhorada pelo envelhecimento. No Brasil, o envelhecimento é tradicionalmente feito pelo armazenamento do destilado em toneis de madeira de lei nacional. O uso de toneis demanda alto custo inicial e longo prazo de imobilização do produto e capital. Alternativas de armazenamento têm sido procuradas, porém sem solução para o envelhecimento. A possibilidade do uso de fragmentos de carvalho para a maturação da cachaça pode proporcionar um maior campo de tipicidades para a bebida. O objetivo deste trabalho foi estudar congêneres voláteis e de maturação em cachaça macerada com fragmentos de madeiras de carvalho proveniente de diferentes florestas francesas (Allier, Vosges e Nièvre) e com diferentes intensidades de tosta (fraca, média e forte). Os congêneres voláteis (acetaldeído, acetato de etila, metanol, 2-butanol, 1-propanol, isobutanol, 1- butanol, álcool isoamílico e ácido acético) foram detectados e quantificados por cromatografia gasosa com detector de ionização de chama (GC-FID) e os congêneres de maturação (ácido gálico, 5-hidroximetilfurfural, furfural, ácido vanílico, ácido siríngico, vanilina, siringaldeído, coniferaldeído e sinapaldeído) foram analisados por cromatografia líquida de alta eficiência (HPLC/CLAE). Testes sensoriais foram realizados para a verificação da aceitação das amostras pelos consumidores quanto aos parâmetros de cor, aroma, sabor e impressão global. A concentração de congêneres voláteis não foi influenciada pelos tratamentos. A presença de congêneres de maturação permitiu concluir que não há contestação na capacidade de ceder compostos entre as madeiras das diferentes florestas, porém a peculiaridade de cada uma delas é destacada quando se analisa a predominância dos compostos de interesse. Em virtude da ampla concentração de congêneres de maturação presente em madeiras de Vosges e de Allier com tosta forte, pudemos supor maior complexidade química na cachaça macerada nessas condições. Seria ainda possível a variação da cachaça macerada mediante uso de fragmentos de carvalho de origens distintas combinando com diferentes intensidades de tosta. Os testes sensoriais apontaram elevada aceitação quanto aos atributos analisados, porém não houve efeito perceptível entre as diferentes madeiras e tostas. O uso de lascas de madeira para a maceração de bebidas não é reconhecido como processo de envelhecimento, podendo ser confundido com ato fraudulento. O presente estudo representa um embasamento teórico-prático para a possível aplicação da metodologia, porém ressalta a importância do estudo comparativo entre o envelhecimento em toneis e por interação de lascas de madeira, visando identificar similaridades e diferenças entre as metodologias e verificar a viabilidade de sua aplicação. / Cachaça is a typical Brazilian spirit, consumed mostly natural. Its quality may be improved by aging. In Brazil the aging process is traditionally done by keeping the spirit in barrels made of national hardwood. The use of barrels demand high initial cost and long-term of immobilization of product and capital. Storage alternatives have been sought, but without solution for aging so far. The possibility of using oak fragments for cachaça maturation may provide a wider field of specificities to the spirit. The objective of this research was to study volatile and maturation congeners in cachaça macerated with fragments of oak wood from different French forests (Allier, Vosges and Nièvre) and with different intensities of toasting (low, medium and high). The volatile congeners (acetaldehyde, ethyl acetate, methanol, 2- butanol, 1-propanol, 1-butanol, isobutanol, isoamyl alcohol and acetic acid) were detected and quantified by gas chromatography with flame ionization detector (GCFID) and the maturation congeners (gallic acid, 5-hydroxymethylfurfural, furfural, vanillic acid, syringic acid, vanillin, syringaldehyde, coniferaldehyde and synapaldehyde) were measured by high performance liquid chromatography (HPLC). Sensory tests were performed to verify consumer´s acceptance concerning the parameters of color, aroma, flavor and global acceptation. The concentration of volatile congeners was not influenced by the treatments. The presence of maturation congeners indicated the ability of the different wood fragments in supplying compounds to the spirit. Nevertheless the peculiarity of each one is highlighted when the compounds predominance is investigated. Due to the high concentration of maturation congeners supplied by Allier and Vosges woods at high toast, we could assume more chemistry complexity for the cachaças macerated in these conditions. It could also be possible modeling cachaça based on maceration with oak fragments from different origins combined with different intensities of toasting. Sensory tests showed high acceptance on the attributes evaluated, but there was no considerable effect between the different woods and toastings. The use of wood fragments to cachaça maceration is not allowed by the Brazilian laws as an aging process, and might be considered a fraudulent act. This study represents a theoretical and practical basis for a possible application of the methodology. It stresses the importance of a further comparative study concerning aging in barrel and by interaction of wood fragments in order to identify similarities and differences between the methodologies and verify the feasibility of its implementation.

L to D isomerization of amino acids in a commercially prepared alkali-treated food-grade soy isolate was investigated. A soy flour product was also investigated as a control which had not been alkali treated. Methionine and valine collected from two soy flour and two soy isolate samples were coupled with L-leucine-N-carboxyanhydride. If both D- and L-forms were present this would produce diastereomeric dipeptide derivatives. The derivatives were separated by ion-exchange chromatography using a TSM Amino Acid Analyzer. Comparison of the sample methionine and valine dipeptide peaks to standard dipeptide peaks revealed the presence of L-valine, L-methionine and D-methionine in both soy flour and soy isolate samples. Methionine was substantially isomerized in both products. D-valine was not observed in either soy flour or soy isolate samples. Thus, isomerization of methionine appeared to occur at a faster rate than valine. Acid hydrolysis, toasting of soy meal, and alkaline treatment are all conditions which may be responsible for the isomerization of methionine. / Master of Science

Le blé est la seconde céréale la plus cultivée dans le monde et constitue un apport majeur de l’alimentation quotidienne. L’effort consenti à continuellement améliorer les qualités meunière et boulangère du blé tendre, s’est fait au détriment du caractère nutritionnel du grain. Ainsi la plupart des produits industriels dérivés des grains de blé sont produits à partir de farines blanches raffinées qui ne contiennent ni le germe ni les sons. Cependant, dans ces différents tissus qui sont éliminés et qui servent essentiellement à nourrir les animaux, se concentrent les principaux micronutriments tels que les vitamines, les minéraux, les fibres et des substances phytochimiques. Les différentes enquêtes épidémiologiques ont bien mis en évidence les conséquences négatives de la déplétion en micronutriments des produits céréaliers raffinés. Dans l’objectif d’une alimentation plus saine voir même préventive, la consommation d’aliments enrichis en micronutriments naturellement présents dans le grain de blé tendre semble être une démarche efficace. Dans cette optique, ce travail de thèse a permis de consolider et d’accroitre les connaissances concernant les voies d’amélioration des teneurs en vitamines des grains de blés tendres ainsi que des produits industriels qui en sont dérivés. En premier, nous nous sommes intéressés au développement d’une méthode simple et rapide basée sur la spectrométrie de masse couplée à la chromatographie liquide pour la détermination simultanée de sept vitamines hydrosolubles dans divers matériels végétaux. Les vitamines présentes dans les différents matériels végétaux furent séparées en moins de 15 min grâce à l’utilisation d’une colonne C18 en phase inverse, et analysées en mode ElectroSpray positif et MRM. La réponse pour toutes les vitamines a été linéaire sur l’ensemble des concentrations étudiées (0.05 to 9 μg/mL) avec des coefficients de corrélation compris entre 0.991 et 1. Les limites de quantification de la méthode analytique ont été évaluées entre 0.09 et 3.5 μg/g. Les précisions intra-journalière et inter-journalière étaient satisfaisantes. La deuxième partie de nos travaux a concerné l’impact des procédés de transformation du grain (production d’une nouvelle fraction de mouture et grillage) sur la teneur en vitamines. Afin de réaliser cette objectif, la méthode développée a été appliquée pour l’analyse simultanée des concentrations en vitamines hydrosolubles contenues dans différentes farines semi-complètes ainsi que dans les pâtons, pains et pains grillés qui en sont dérivés. En parallèle, les concentrations endogènes des vitamines E, de la Lutéine et du β-sitostérol ont également été évaluées dans le même matériel. Nous avons mis en évidence que les concentrations en acide nicotinique, pyridoxale, pyridoxine et acide pantothénique étaient significativement plus élevées dans les gros sons que dans les autres fractions de moutures, alors que les concentrations en β-sitostérol, lutéine, α-tocotriénol, α-tocophérol et thiamine (20.87 μg/g DM)étaient plus importantes dans la fraction de mouture enrichie. L’étape de grillage induit une augmentation significative en α-tocophérol (+216%), β-γ-tocophérol (+52%), α-tocotriénol (+83%), β-γ-tocotriénol (+32%), acide nicotinique (+55%), nicotinamide (+97%) et en pyridoxine (+77%). L’ensemble de ces résultats nous a permis de montrer qu’un enrichissement de farine blanche par la fraction de mouture dite enrichie pourrait potentiellement permettre d’accroître les produits qui en dérive en vitamine E. De plus le grillage pourrait libérer des composés bioactifs, augmentant ainsi leur biodisponibilité et la valeur nutritionnelle des pains. (...) / Wheat is the second largest crop cultivated around the world and constitutes a major part of the daily diet in Europe. During the course of improving the baking quality of wheat cultivar, most of the nutritional attributes have been underestimated. It is therefore unfortunate that most of wheat-based food products are mostly produced from refined white flour from which peripheral tissues (germ and envelopes) are removed. However, these tissues, which are eliminated and serve mainly for animal feeding, contain most of the vitamins, minerals, fiber and phytochemicals of the grain. It is becoming evident that many of the health benefits associated with the consumption of whole grain cereal products, relate to the enhanced intake of micronutrients, phytochemicals and dietary fiber. In the context of consuming wheat derived foods with enhanced nutritional value, as part of a healthy diet, this thesis provide results which strengthen the knowledge of vitamins accumulation in common wheat and in wheat-based food products. Firstly, we have developed a simple and rapid method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) for the simultaneous screening of seven water soluble vitamins in various wheat-based food materials. The vitamins present in the test materials were separated in less than 15 min by using a reverse-phase C18 column, and analyzed by positive ion electrospray selected reaction monitoring MS/MS. The MS response for all the vitamins was linear over the working range (0.05 to 9 μg/mL) with correlation coefficients ranging between 0.991 and 1. Limits of quantification in the different food materials ranged from 0.09 to 3.5 μg/g. Intra-day and inter-day precision was found satisfactory. The second part of our research, have focused on monitoring the levels of vitamins upon the wheat-based foods processing operations, such as production of new wheat milling fraction (consisting in enriched fraction) and breadmaking toasted bread. In order to achieve this goal, the developed method was applied for the simultaneous analysis of the water-soluble vitamin natural content of different semi-coarse wheat flours and in their corresponding baking products. In addition the vitamin E, Lutein and β-sitosterol natural content was also measured in the same materials. It was shown that the concentration of nicotinic acid, pyridoxal, pyridoxine, pantothenic acid were significantly higher in the coarse bran than in the other milling fractions, while the concentration of β-sitosterol, lutein, α-tocotrienol, α-tocopherol and thiamin (20.87 μg/g DM) were the highest in the enriched fraction. The toasting step induced a significant increased of α-tocopherol (+216%), β-γ-tocopherol (+52%), α-tocotrienol (+83%), β-γ-tocotrienol (+32%), nicotinic acid (+55%), nicotinamide (+97%) and of pyridoxine (+77%). Furthermore, it was demonstrated that the enriched fraction could be a functional ingredient in order to enrich wheat-based products in fat soluble vitamins and that the toasting process could release bound bioactive compounds and led to enhance the nutritional quality of bread. (...)

Made available in DSpace on 2014-07-29T16:16:33Z (GMT). No. of bitstreams: 1 dissertacao july ana s tavares.pdf: 2960047 bytes, checksum: db90116ac492ad8556d54577789f08f3 (MD5) Previous issue date: 2010-10-01 / Rice is a cereal consumed primarily as whole grain, and its composition and fractions are subject to varietal differences, environmental variations, handling, processing and storage. Broken grains of rice are fractions generated during processing and may represent between 14% and 60% of total grains. The processing of broken grains in the form of flour is an alternative to the use of this byproduct in the food industry. The thermal changes, such as toasting, could modify the sensory characteristics of rice flour due to the occurrence of reactions such as Maillard, and changes in the technological characteristics such as absorption capacity and water solubility, viscosity and amylose content. This research studied the influence of moisture content and toasting time in microwave on physical characteristics (size, modulus of fineness, color, viscosity, water absorption index and water solubility index) chemical (moisture, ash, crude protein, fat, carbohydrates and amylose content) and sensorial of raw rice flour and toasted of cultivars BRS Primavera, BRS Sertaneja and IRGA 417. We also determined the income benefit, whole grain and the degree of polishing of rice grains of these cultivars and scanning electron microscopy of some raw flour and toast. He was employed a Central Composite Rotational Design (CCRD), which includes a factor of 22 over 3 replications at the central point and axial 4, totaling 11 treatments for each cultivar. The cv. BRS Sertaneja presents higher income benefit, while cv. IRGA 417 has a higher yield of integers and degree of polish. The cv. BRS Primavera has a higher percentage of broken grains may be suitable for production of flour. The flour of raw rice and toast were placed between thin and medium. The color of the raw flours from three cultivars are significantly different. The toasting process causes the darkening, reddening and yellowing of the meal toast. The humidification followed by toasting in microwave rice flours from three cultivars did decrease the formation of paste, moisture, protein, lipid and amylose, increasing the absorption index and water solubility and ash content, and carbohydrates . The Free Profile enabled to differentiate the samples on the cultivar and time of toasting. The longer, the flour toasts were characterized with more intense flavor and aroma of toasted and / or burned, and granularity in appearance and texture. / O arroz é um cereal consumido principalmente como grão inteiro, sendo que sua composição e de suas frações estão sujeitas às diferenças varietais, variações ambientais, de manejo, de processamento e de armazenamento. Grãos quebrados são frações de arroz gerados durante o beneficiamento e podem representar entre 14% e 60% do total dos grãos beneficiados. O processamento de grãos quebrados sob a forma de farinha é alternativa para uso deste subproduto na indústria de alimentos. As modificações térmicas, como a torração, poderiam modificar as características sensoriais da farinha de arroz devido à ocorrência de reações como a de Maillard, além de modificações nas características tecnológicas como capacidade de absorção e solubilidade em água, viscosidade de pasta e teor de amilose. Este trabalho objetivou verificar a influência das variáveis umidade e tempo de torra em micro-ondas sobre as características físicas (granulometria; módulo de finura; cor; viscosidade; índice de absorção de água e índice de solubilidade em água), químicas (umidade, cinzas, proteína bruta, lipídios, carboidratos e o teor de amilose) e sensorial das farinhas de arroz cruas e torradas das cultivares BRS Primavera, BRS Sertaneja e IRGA 417. Foram também determinados a renda do benefício, rendimento de inteiros e grau de polimento dos grãos de arroz destas cultivares, além de microscopia eletrônica de varredura de algumas farinhas cruas e torradas. Foi empregado um Delineamento Composto Central Rotacional (DCCR), que inclui um fatorial de 22 mais 3 repetições no ponto central e 4 axiais, totalizando 11 tratamentos para cada cultivar. A cv. BRS Sertaneja apresenta maior renda do benefício, enquanto a cv. IRGA 417 possui maior rendimento de inteiros e grau de polimento. A cv. BRS Primavera possui maior porcentagem de grãos quebrados podendo ser indicada para produção de farinha. As farinhas de arroz cruas e torradas foram classificadas entre muito fina e média. A cor das farinhas cruas das três cultivares são significativamente diferentes. O processo de torra provoca o escurecimento, avermelhamento e amarelamento das farinhas torradas. A umidificação seguida de torra em micro-ondas nas farinhas de arroz das três cultivares fez diminuir a formação de pasta, a umidade, o teor protéico, lipídico e de amilose, aumentando o índice de absorção e solubilidade em água e o conteúdo de cinzas e carboidratos. O Perfil Livre permitiu diferenciar as amostras quanto a cultivar e o tempo de torra. Quanto maior o tempo, as farinhas torradas caracterizaram-se com aroma e sabor mais intenso de torrado e/ou queimado, além de granulosidade na aparência e textura.