STUDY CONCERNING PROTEINS EXTRACTION PROCESS FROM PEAS IN DIFFERENT WORK CONDITIONS

Abstract

Peas represent a valuable source of vegetal proteins, quantitatively and qualitatively. Dry peas contain 24.5% proteins which contain all essential amino-acids, having an excess of lysine, still being short in methionine. Proteins are represented by globulin and legumelin, are easy soluble, having high digestibility. Carbohydrates are represented by starch but also by saccharose, in proportion of 5-10%. The amount of lipids is small, but there are in great amounts lecithin. Peas also contain vitamins represented by tocopherols, vitamins from B group and various mineral substances. For protein extraction from any biologic material, the material must be preliminarily fine powdered after what the actually extraction is made by treatment with solvents that can be water, salts solutions, mixture of water-ethanol, or diluted solutions of acids or bases. In order to intensify the extraction process normally is lurched to the mechanical stirring of the mixture, expanding in this way the substance transfer according to Fick’s law. It has been certificated that by applying an ultrasound field in the extraction process, greatly increases the substance transfer and implicitly the extraction speed. This is due the acoustic cavitation phenomenon which appears in a liquid exposed in an ultrasound field with sufficient intensity. The acoustic cavitation is manifested by forming cavitational bubbles which in the first phase are increasing their volume and after that they suddenly implode creating a powerful shock wave which is propagated in the solution. Due this shock waves in which the pressure can reach 10000 atmospheres, the cellular walls are destroyed and the cellular content passes in the external medium. Also due the acoustic cavitation, in solution appear powerful current which mixes the solution components. In the current work the comparative extraction with water and NaOH diluted solution was used by mechanical stirring and by ultrasound field exposure, respectively. The extracted proteins proportion is higher by using the extraction in an ultrasound field. Also, from the two solvents used it is noticed that by using the NaOH solution a better effective power of extraction was obtained comparative with the distilled water case. So, by using the assisted extraction of ultrasounds, by using as a solvent the NaOH solution, the maximal proportion of proteins was extracted, that is, approximately 96% of total proteins from peas, according to data concerning the composition of the peas flour extracted from bibliography