Determinação de fosfolipídios por método de turbidez: precisão e influência de fatores físico-químicos do óleo de soja

Abstract

The quality of soybean oil produced depends on many factors from planting to processing. Phospholipids have high commercial value when extracted from crude oil, because when hydrated they become soy lecithin, a natural emulsifier. In addition, phospholipid extraction facilitates upcoming processes such as oil neutralization, clarification and deodorization. The soybean processing industries carry out in their laboratories analyses to control the phospholipid content in soybean oil, in order to control the process for the subsequent stage of refining, thus avoiding a high expenditure with insum for the removal of phospholipids, as well as to meet the current legislation that establishes a maximum of 1 ppm i.e. 1 gram/ 1000Kg phospholipids in refined oil. Phospholipids are usually determined by colorimetry analysis with the aid of uv-vis spectrophotometer where the compost obtained from molybdenum blue is performed, whose color intensity is proportional to the concentration of phosphorus ions present in the sample, this analysis takes about 4 hours to complete. One of the alternative methodologies is the turbidity method. This device (Turbidimeter) has the purpose of reducing the analysis time by 95%, however, there are doubts as to the accuracy, because it is believed that physical-chemical factors of this oil can cause interference in the reading of the turbidimeter. This proposal then sought to compare the two methodologies determination of phospholipids in degummed oil (colorimetry and turbidimeter), from internal samples of the partner industry that present variations in the physical-chemical, chlorophyll, acidity and soap properties. For this purpose, statistical tools such as Person correlation analysis, p-value analysis, and regression models were used to evaluate the influence of the physical-chemical parameters obtained in the results of the 42 samples. However, it was concluded through the Person correlation that there are significant differences between the two methods for phospholipid analysis, losing some validation concepts: such as robustness and accuracy. Equations were assembled on the two methods of analysis using the regression model, where a great influence of the chemical physical factors Chlorophyll and Soaps was observed in the readings, mainly by the Turbidity method according to the values indicated in the equations. It is concluded that spectrophotometer analyses bring more confidence of results to laboratories that work with phospholipids even with a longer time for this, and turbidity analysis can undergo further research and improvement in the method, taking into account the particularities of each industry for this.