Processo de ozonização dos grãos de trigo: cinética de reação e efeito na qualidade destes e da farinha

• Autor(a) principal: Silva, Tales Afonso da
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/3599
• topic: Desinfecção microbiológica; Gás ozônio; Microbiological disinfection; Ozone gas; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA

The need to find alternatives that are effective in controlling insect pests and microorganisms stimulates researches development aimed to find new methods and techniques that enable the maintenance of product quality. One alternative is to use ozone gas (O3), a strong oxidant and antimicrobial agent, which can be generated on site by an electrical discharge, eliminating the need for handling, storage, or packaging disposal. This work was developed with the aim of analyzing the reaction kinetics of ozone gas on the grains mass of wheat, to evaluate the ozonation effect on physical, physiological, and microbiological features of wheat grains and physico-chemical and rheological properties of wheat flour obtained from ozonized grains. For the ozonation process on wheat grains, cylindrical containers of polyvinyl chloride (PVC) were used with 20 cm in diameter, 50 cm in height, and 10 kg capacity. The ozone gas was injected into the cylinder through a connection on the top lid with a flow of 2.0 L min-1. Wheat grains (7.5 kg) were ozonized at concentrations of 0.54, 1.07, 1.61, and 2.14 mg L-1. From each concentration, we studied the reaction kinetics of gas in grains mass, by determining the saturation time and decomposition rate. With results of saturation time, ozonation periods were established in order to evaluate the gas residual effect on physical and physiological quality, microbiological disinfection of grains, and physico-chemical and rheological properties of wheat flour from ozonized grains. To compare the results, wheat grains were submitted to control treatment with the atmospheric air in the same conditions of treatment with ozone gas. Results of grains mass saturation were submitted to Linear Response Plateau (LRP) regression analysis. Data from gas decomposition in grains mass were fitted to zero order model of first and second order by regression analysis. Results of physical and physiological quality of grains and physico-chemical and rheological properties of wheat flour were subjected to completely randomized design (CRD) with two treatments for each exposure period and three replications. From obtained values, we performed analysis of regression variance. Periods of 100, 90, 75, and 36 hours of ozonation at concentrations of 0.54, 1.07, 1.61, and 2.14 mg L-1, respectively, were sufficient to saturate the grains mass of wheat. It was found that the first order model was that best fit the data decomposition. Treatment with ozone gas at concentrations of 0.54, 1.07, 1.61, and 2.14 mg L-1 in their respective periods of exposure did not affect grains quality, with the exception of electrical conductivity and germination. None of the analyzed farinographic and extensographic parameters was influenced by the ozonation process. Results of microbiological analysis for the characterization of wheat grains were within the standard of identity and quality established by RDC (Regional Development Council) Resolution No. 12. Overall, it is concluded that increasing ozone concentration reduced the saturation time of the grains mass of wheat, the rate of decomposition of the gas increased with increasing ozone concentration, and the ozonation process of wheat grains did not affect the quality of grains and wheat flour.