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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.1995.tde-20220207-171113
Document
Author
Full name
Ana Claudia Chesca
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1995
Supervisor
Title in Portuguese
Equipamento experimental para determinação de isotermas de adsorção de farináceos
Keywords in Portuguese
ALIMENTOS FARINÁCEOS
EQUIPAMENTOS
FARINHAS
ISOTERMAS DE ADSORÇÃO DE ÁGUA
Abstract in Portuguese
No presente trabalho, foi realizada a avaliação do desempenho de equipamento experimental, para a determinação prática de curvas de umidade de equilíbrio ou isotermas de adsorção. O equipamento construído é de baixo custo, de fácil construção e operação, não exigindo ferramentaria e mão-de-obra especializada. Para o ajuste dos valores de atividade de água (Aa) no interior do equipamento, foram usadas soluções saturadas de sais, abrangendo o âmbito de maior interesse para fins práticos de armazenagem e conservação de materiais particulados, ou seja 0,51; 0,57; 0,67; 0,75; 0,79; 0,84; 0,91. Foram empregadas para a determinação das isotermas de adsorção, farinha de mandioca "Deusa", fubá mimoso "Kitano", farinha integral e sem casca desoja das variedades Céu Azul e IAC-08. Foram utilizadas amostras recicladas e não recicladas dessas farinhas. As isotermas de adsorção desses materiais foram traçadas a 30°C, 35°C e 40°C. O tempo total de exposição de uma amostra a uma dada Aa foi de 34 horas, com pesagens intermediárias as 10ª, 11ª, 12ª, 24ª, 25ª, 26ª, 27ª, 28ª, 29ª, 30ª, 31ª, 32ª, 33ª e 34ª horas. A partir da última tomada de dado, ou seja, na 34ª hora, as amostras eram submetidas às análises microbiológicas, com o objetivo de se determinar a presença de microrganismos amilolíticos. Observou-se que os tempos necessários para as farinhas utilizadas entrarem em equilíbrio, com as atividades de água estudadas, foram sensivelmente mais curtos, da ordem de 10 a 12 horas, quando comparados com métodos estáticos de equilíbrio.
Title in English
Experimental equipment for determination of adsorption isotherms of various flours
Abstract in English
In the actual work the performance evaluation of an experimental equipment for practical determination of moisture equilibrium curves or adsorcion isotherms were carried out. The built equipment is inexpensive, of easy construction and operation, so that it does not need specialized tools or manocuvre. Salt satured solutions were used to adjust the water activity (Aw) inside the equipment, compressing the highest scope of values in practical storage and conservation of particulated material, which are 0,51; 0,57; 0,67; 0,75; 0,79; 0,84 and 0,91. In order to determine the adsorption isotherms, "Deusa" manihot flour, "Kitano" corn meal, whole and coreless soybean floury from Céu Azul and IAC- 08 cultivars. Recycled and non-recycled samples of these flours were used. The adsorption isotherms of these materials were taken at 30°C, 35°C and 40°C. The total exposition time of the samples to a given Aw was 34 hours with intermediary weightings at the 10th, 11th, 12th, 24th, 25th, 26th, 27th, 28th, 29th, 30th, 31st, 32nd, 33rd and 34rd hours. After the last data taking, which was at the 34th hour, the samples were submitted to microbiological analysis, in order to determine the presence of search degradating microrganisms. It has been observed that necessary time to settle the equilibrium between the tested flours and the studied water activities (Aw) were sensibly shorter, ranging from 10 to 12 hours, when compared to static equilibrium methods.
 
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Publishing Date
2022-02-07
 
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