A fast microwave-assisted procedure for loss on drying determination in saccharides

Abstract

Um procedimento rápido para determinação de perda por dessecação (LOD) foi desenvolvido empregando aquecimento por radiação micro-ondas. Amostras de sacarídeos foram utilizadas e diferentes parâmetros foram avaliados, tais como a posição da amostra na cavidade do micro-ondas, massa de amostra e tempo de irradiação. Massas de amostra de 1 g e tempo de irradiação entre 15 e 25 min foram suficientes para a determinação da perda por dessecação de todos sacarídeos. Os resultados obtidos para perda por dessecação assistida por micro-ondas (MALOD) foram comparados com os resultados obtidos por LOD convencional em estufa e não apresentaram diferença significativa. O tempo de análise foi reduzido de 2,4 a 15 vezes, quando comparado ao sistema convencional de LOD e o desvio padrão relativo das medidas foi inferior a 1%. Até 16 amostras podem ser processadas simultaneamente, tornando o procedimento MALOD apropriado para análise de rotina.A fast procedure for loss on drying (LOD) determination was developed using microwave radiation. Samples of commercial saccharides were dried and the influence of sample position inside the microwave cavity, sample mass and irradiation time were evaluated. Sample mass of 1 g and irradiation time between 15 to 25 min were enough to LOD determination for all saccharides. Results obtained using the proposed microwave-assisted loss on drying (MALOD) procedure were compared with those obtained by conventional LOD determination using an oven and no statistical difference was found among results of these techniques. Using MALOD procedure the relative standard deviation was below 1%. The time for analysis was reduced from 2.4 to 15 times when compared to conventional LOD determination and up to 16 samples could be simultaneously processed making MALOD procedure suitable for routine analysis.Keywords: loss on drying, saccharides, microwave, food and pharmaceutical samples IntroductionLoss on drying (LOD) determination is a parameter often evaluated to access the quality of products. Several applications of LOD can be found in industry, in special for food and pharmaceutical industries, which currently use LOD to determine the amount of volatile matter (in general, water) that is driven off under specific conditions. 1-3 The LOD determination is relatively simple to be performed and results with relatively good precision can be obtained resulting in a widespread use. For example, in the 30 th edition of The United States Pharmacopeia more than one thousand monographs recommended the use of LOD in their tests that makes it a parameter that must be routinely evaluated in current quality control. 4 The procedures recommended for LOD determination can be performed at different conditions of drying such as pressure (atmospheric or vacuum) and temperature (with or without heating). [1][2][3] In some cases, the use of a desiccant to help the drying process (e.g. diphosphorus pentoxide) is recommended, Bizzi et al. 377 Vol. 22, No. 2, 2011 specially for mild drying conditions used for samples that can...

Are Infrared and Microwave Drying Suitable Alternatives for Moisture Determination of Meat Products?

“…As the mass of the sample subjected to procedure is not able to absorb all radiation generated by the magnetron, it was necessary to adapt a polyethylene hose (2 m in length and 5 mm diameter) with a constant flow of water (700 mL/min) to absorb the excess of radiation, as described by Bizzi et al . (). For safety reasons, a microwave leak detector was used periodically during the experiments to verify a possible loss of radiation in the holes made in the apparatus (model LT‐2D, 2,450 MHz, the maximum limit of 5 mW/cm 2 , Milestone SRL, Sorisole, Italy).…”

“…These procedures are generally performed in an oven and provide the results with relatively good accuracy and precision, resulting in widespread use (Bizzi et al . ). Certainly one of the reasons for its maintenance as official method is the fact that this simple procedure can be performed in all analytical laboratories with low cost (Isengard ).…”

“…Recently, a simple, quick and inexpensive procedure for determination of LOD in saccharides using microwaves was proposed by Bizzi et al . (). The results obtained by the authors were comparable to those of the conventional method, but with a reduction of up to 15 times in the time for determination.…”

Determinação do teor de umidade em grãos empregando radiação micro-ondas

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“…BIZZI et al (2011) adaptaram um forno de micro-ondas doméstico para a MALOD de sacarídeos, obtendo resultados concordantes com o método ofi cial, com redução do tempo de análise de até 15 vezes. Neste trabalho, é proposto o uso da MALOD para amostras de diferentes grãos, buscando reduzir o tempo de análise.…”