Investigating the effect of extraction methopds on the propertiesand gossypol content of cotton seed protein

Cotton is an industrial plant and widely used in many sectors. Cotton branches, seeds, fibers are source of valuable components which altogether made cotton an important natural resource. While the fiber part of cotton is used in the textile industry, the cotton seed part is evaluated due to its protein, oil and mineral content. Cottonseed is considered an important source of nutrition and income because of its 18-35% protein and 21-40% oil content. After the oil is removed from the cottonseed, the part called pulp is used as animal feed because it displays high protein content. In recent years there has been an increase in investigations aimed at identifying alternative plant protein sources. In this context, cottonseed meal also stands out as an important natural protein source. This study focused on determining the functional, technofunctional and characteristic properties of proteins isolated from defatted cottonseed by different extraction methods (Alkali extraction, Ultrasound-assisted extraction, Microwave-assisted extraction and Acetone extraction). The characteristic features of cottonseed proteins obtained by different extraction methods were determined according to their gossypol ratios. Among the different extraction methods used, protein and free gossypol ratios were measured as Alkaline extraction 66.78 %- 152.11ppm, Ultrasound assisted extraction 80.52 %- 115.36ppm, Microvawe assisted extraction 82.49 %- 104.26ppm, and Acetone extraction 70.45%- 142.65ppm, respectively. Technological properties of cottonseed proteins including moisture content, water activity, color, fluidity and wettability, water holding capacity (WHC), foaming capacity, foam stability, emulsion activity index (EAI) and emulsion stability index (ESI) were measured. The unique structures and components of the proteins were determined by Fourier transform infrared spectroscopy (FTIR). In addition, detailed analyzes of surface morphologies were made with scanning electron microscopy (SEM) and thermal gravimetric analyzes (TGA) were performed to measure the behavior of proteins against different temperatures. As a result, it has been concluded that the proteins obtained by microvawe extraction displayed remarkable attributes in terms of their functional properties.