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InfluĂȘncia do grau de branqueamento no rendimento industrial e nas propriedades de cozedura do arroz
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O arroz (Oryza sativa L.) Ă© um dos cereais mais importantes mundialmente, estando na dieta diĂĄria de metade da população. O cultivo desta planta deve ser realizado em condiçÔes adequadas ao seu crescimento, pois a alteração destas traduz-se num arroz com caracterĂsticas fĂsicas, nutricionais e quĂmicas diferentes do habitual. O arroz Ă© constituĂdo por proteĂnas, lĂpidos, vitaminas e minerais localizados nas camadas mais externas do grĂŁo e por amido, presente em maior quantidade, localizado no centro. Para tornar o arroz mais apelativo ao consumidor, o seu processamento sofre uma sĂ©rie de transformaçÔes nomeadamente o branqueamento e polimento que retiram as camadas mais externas ao grĂŁo tornando-o mais branco e brilhante. O principal objetivo deste trabalho consistiu em estudar a influĂȘncia de dois graus de branqueamento no rendimento industrial e nas propriedades de cozedura do arroz em oito variedades da subespĂ©cie JapĂłnica. Para as oito variedades de arroz determinaram-se as caracterĂsticas biomĂ©tricas, o teor de amilose, de humidade, tempos de cozedura e propriedades reolĂłgicas (perfil de viscosidade, força de extrusĂŁo e perfil de textura). O comprimento das amostras estudadas, assim como, a relação comprimento/largura diminuĂram no segundo grau de branqueamento. Todas as amostras apresentaram um teor de humidade inferior aos 14%. O segundo grau de branqueio resultou em grĂŁos mais brancos, o que diminuiu o rendimento industrial e a quantidade de grĂŁos inteiros, e aumentou a quantidade de trinca. NĂŁo foi possĂvel estabelecer estatisticamente diferenças entre as mĂ©dias na mesma variedade, dos parĂąmetros de temperatura de gelatinização, tempo do pico, vala de viscosidade, breakdown e adesividade, no entanto, todas apresentaram ligeiras variaçÔes nos resultados. Nos restantes parĂąmetros estudados houve diferenças significativas dentro de determinadas variedades. O grĂŁo Ă© constituĂdo na sua maioria por amido, o que faz com que a quantidade de amilose/amilopectina influenciem em grande parte o comportamento do arroz no momento da cozedura e posterior degustação. Contudo, a presença de outros compostos, como a proteĂna, alteram as propriedades de cozedura e de textura, sendo por isso, importante a determinação deste parĂąmetro para compreender melhor as anĂĄlises realizadas. Seria necessĂĄrio realizar este estudo com graus de branqueamento mais dispares para melhor compreender a sua influĂȘncia. A continua monitorização dos parĂąmetros estudados por parte da indĂșstria arrozeira, garante um arroz com elevada qualidade para o consumidor, pois a composição quĂmica e nutricional das variedades difere e consequentemente o seu comportamento.
Rice (Oryza sativa L.) is one of the most important cereals in the world, being in the daily diet of half of the population. The cultivation of this plant must be carried out in conditions suitable for itÂŽs growth, as the alteration of these translates into rice with physical, nutritional and chemical characteristics different from the usual. Rice is made up of proteins, lipids, vitamins and minerals located in the outermost layers of the grain and starch, present in greater quantities, located in the center. To make rice more appealing to the consumer, itÂŽs processing undergoes a series of transformations, namely blanching and polishing, which remove the outermost layers of the grain, making it whiter and shinier.The main objective of this work was to study the influence of two degrees of bleaching on industrial yield and cooking properties of rice in eight varieties of the JapĂłnica subspecies. For the eight rice varieties, the biometric characteristics, amylose content, moisture content, cooking times and rheological properties (viscosity profile, extrusion strength and texture profile) were determined. The length of the studied samples, as well as the length/width ratio, decreased in the second degree of bleaching. All samples showed a moisture content below 14%. The second degree of bleaching resulted in whiter grains, which decreased the industrial yield and the amount of whole grains and increased the amount of cracks. It was not possible to establish statistically differences between the means in the same variety, of the parameters of gelatinization temperature, peak time, viscosity trough, breakdown and adhesiveness, however, all presented slight variations in the results. In the remaining parameters studied, there were significant differences within certain varieties. The grain is mostly made up of starch, which means that the amount of amylose/amylopectin largely influences the behavior of the rice at the time of cooking and subsequent tasting. However, the presence of other compounds, such as protein, alter the cooking and texture properties, so it is important to determine this parameter to better understand the analyses carried out. It would be necessary to carry out this study with more disparate degrees of bleaching in order to better understand its influence. The continuous monitoring of the parameters studied by the rice industry guarantees a rice with high quality for the consumer, as the chemical and nutritional composition of the varieties differs and consequently their behavior.
Rice (Oryza sativa L.) is one of the most important cereals in the world, being in the daily diet of half of the population. The cultivation of this plant must be carried out in conditions suitable for itÂŽs growth, as the alteration of these translates into rice with physical, nutritional and chemical characteristics different from the usual. Rice is made up of proteins, lipids, vitamins and minerals located in the outermost layers of the grain and starch, present in greater quantities, located in the center. To make rice more appealing to the consumer, itÂŽs processing undergoes a series of transformations, namely blanching and polishing, which remove the outermost layers of the grain, making it whiter and shinier.The main objective of this work was to study the influence of two degrees of bleaching on industrial yield and cooking properties of rice in eight varieties of the JapĂłnica subspecies. For the eight rice varieties, the biometric characteristics, amylose content, moisture content, cooking times and rheological properties (viscosity profile, extrusion strength and texture profile) were determined. The length of the studied samples, as well as the length/width ratio, decreased in the second degree of bleaching. All samples showed a moisture content below 14%. The second degree of bleaching resulted in whiter grains, which decreased the industrial yield and the amount of whole grains and increased the amount of cracks. It was not possible to establish statistically differences between the means in the same variety, of the parameters of gelatinization temperature, peak time, viscosity trough, breakdown and adhesiveness, however, all presented slight variations in the results. In the remaining parameters studied, there were significant differences within certain varieties. The grain is mostly made up of starch, which means that the amount of amylose/amylopectin largely influences the behavior of the rice at the time of cooking and subsequent tasting. However, the presence of other compounds, such as protein, alter the cooking and texture properties, so it is important to determine this parameter to better understand the analyses carried out. It would be necessary to carry out this study with more disparate degrees of bleaching in order to better understand its influence. The continuous monitoring of the parameters studied by the rice industry guarantees a rice with high quality for the consumer, as the chemical and nutritional composition of the varieties differs and consequently their behavior.
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Keywords
Arroz (Oryza sativa L.) JapĂłnica Kett rendimento industrial cozedura