Ozonização da farinha de trigo: cinética de reação e efeito nas características tecnológicas

• Autor(a) principal: Paes, Juliana Lobo
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/711
• topic: Gás ozônio; Panificação; Qualidade; Ozone gas; Breadmaking; Quality; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA::ENGENHARIA DE PROCESSAMENTO DE PRODUTOS AGRICOLAS

The aims of the study were to investigate the reaction kinetics of ozone, their effects on the physical-chemical, rheological, breadmaking and sensory properties of flour, and the possible residual effect of this gas on the inhibition of microorganisms in bread. The ozonization of flour at concentrations 0.54 mg L-1 up to 17 hours, 1.07 mg L-1 until 13 h and 1.61 and 2.14 mg L-1 up to 10 h was performed on a prototype consists of a cylindrical drum and a mixing system for helical thread. Ozone gas was produced by a generator, to which oxygen was supplied industrial and quantification was carried out by iodometric method. The saturation time, decay rate and half-life were determined by studying reaction kinetics. The effects of ozone on physical-chemical characteristics of wheat flour were evaluated by water, ash and protein content, pH, falling number, color and gluten content. The rheological properties were evaluated by farinograph and extensograph. Analysis of breadmaking quality (specific volume, firmness and color of crust and crumb) werecarried out in bread made from wheat flour ozonizated or not. It was adopted acceptance test for the sensory analysis of wheat flour and breads. The inhibitory effect of ozone gas was analyzed by counting of filamentous fungi and yeast and inoculation of Penicillium sp in breads. The ozone saturation time was 812, 434, 370 and 342 min at concentration of 0.54, 1.07, 1.61 and 2.14 mg L-1, respectively. The decomposition kinetic model obtained was first order, in which the decomposition rate constant average was 0.23 ± 0.008 min-1 and half-life 3.02 ± 0,081 min. Overall, the centesimal composition and pH of the wheat flour were not affected when compared whit the control, but these parameters reduced by increasing the exposure period. The falling number of flour ozone was significantly different from control and increased with exposure period. The brightness and the coordinates L* and a* of ozonated flour were significantly higher when compared with the control and increased with exposure period, indicating an increase in intensity of the blank, while b* coordinate reduced due to oxidation of yellow pigments. The bleaching effect of ozone gas in flour can be confirmed by the total difference in color. It was observed that the ozonation in different concentrations and exposure period had a differential effect on each rheological characteristic wheat flour, modifying the viscoelastic properties of the dough. Breadmaking quality of wheat flour ozonizated at 0.54 mg L-1 during 9 and 11 h and 1.07 mg L-1 for 1 and 4 h was similar flour control. These treatments were used to make the breads. The flour ozonated had higher acceptability than the control and bread made from flour ozonated was considered a quality product with good acceptance by the judges. The ozonation of flour did not inhibit the growth of filamentous fungi in breads. Concluded that the wheat flour ozonated at concentrations of 0.54 mg L-1 for 9 and 11 h and 1.07 mg L-1 for 1 and 4 h presents great breadmaking quality.