Desenvolvimento de um novo processo de limpeza e condicionamento de grãos de trigo.

Abstract

The wheat milling process currently used by millers all over the world comprises four unit operations: the cleaning of the grains - with the aim to separate the sound grains of its impurities; the tempering – for grains reach its ideal moisture and to get the best flour extraction rate; the milling of the grains and the flour classification through a sieving system where some flours with different particle sizes are produced. In the present work, it was developed a new wheat cleaning process based on the densities of the sound grains and its impurities making use of two unit operations. The first one is made in a two stage calcium chloride pools of different concentrations followed by an air drying of the grains at room temperature (the second one) to get rid of the superficial grain solution. The water content of the grains at the end of the first operation was 17,96 % for a 45 second operation time and 12,74% after the air drying of the grains that was up in 4,0 minutes in the room temperature at an air outflow of 0,507 m3.s-1. The yield of the experimental milling of the grains by the new process was 60,02% versus 47,67 % by the traditional process. The ash amounts of the flours obtained from the grains cleaned by the new and traditional processes were respectively: 0,58 % and 0,59%. The chloride amounts of the flours obtained from the grains cleaned by the new and traditional processes were respectively: 15,52 mg.100g-1; 0,95 mg.100g-1 , and the calcium amounts of the same flours were respectively: 43,53 mg.100g-1 and 5,89 mg.100g-1 .The total counting of the yeast, fungus and Bacillus cereus spp. Before and after cleaning the grains by the new and the traditional process were as following: 10 UFC.g-1 ; 3 x 102 UFC.g-1 ; < 10 UFC.g-1 ; <102 UFC.g-1 ; < 10 UFC.g-1 and 3 x 102 UFC.g- 1. The taste of the breads made with the flours from the grains cleaned by the two process were not significantly different at 5,0% level. The overall results showed that wheat grains could be cleaned by the proposed method without either developing gluten during milling nor causing bitter taste to bread when calcium chloride solutions were used to separate sound grains of its impurities.