Investigating the extraction of carrageenan from red algae and its purification process for use in Food products

The purpose of this research is to extract kappa carrageenan from Kappaphycus alvarezii algae and to investigate the factors influencing the different characteristics of carrageenan. In this research, the extraction of kappa-carrageenan was done by different methods, including extraction with potassium chloride and calcium hydroxide, extraction with isopropyl alcohol and extraction by spray drying method.Quantitative and qualitative characteristics of kappa carrageenan including color, pH, moisture content, total ash, acid insoluble ash, sulfate content, water absorption capacity, minimum gelation concentration, gel strength, syneresis, viscosity, efficiency, total microorganism count, morphology and infrared Fourier transform spectroscopy were investigated. Based on infrared Fourier transform spectroscopy, the highest degree of similarity between the types of kappa carrageenan samples extracted in this research with the commercial sample was observed in the extraction method with 6% potassium hydroxide, and the extraction efficiency in this method is 34.84%. It was found that it is desirable.Also, the microorganism count test with the result of 1500 Cfu/g indicated the high level of cleanliness of the gel and the possibility of using it in food products. Extraction with 6% potassium hydroxide, in addition to high extraction efficiency, has a very high structural similarity with the commercial sample. On the other hand, all the evaluated quantitative and qualitative characteristics of the extracted kappa-carrageenan were in full compliance with the relevant standards, and therefore, the use of this method in extraction is suggested.