EFFECTS OF EXTRUSION ON κ-CARRAGEENAN/AGAR MIXED GEL TYPE

• Published in: Journal of texture studies Vol. 40; no. 6; pp. 646 - 656
• Main Authors: KIM, KEEHYUK, LEE, SEUNG JU
• Format: Journal Article
• Language: English
• Published: Malden, USA Malden, USA : Blackwell Publishing Inc 01-12-2009; Blackwell Publishing Inc; Wiley
• Subjects: Biological and medical sciences; Extrusion; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Methods of analysis, processing and quality control, regulation, standards; mixed gel types; phase inversion; κ-carrageenan/agar; Extrusion
• ISSN: 0022-4901; 1745-4603
• DOI: 10.1111/j.1745-4603.2009.00203.x

κ-Carrageenan and agar have a slight mutual thermodynamic incompatibility. Therefore, this study examined the effects of extrusion on the synergy ofκ-carrageenan and agar mixed gels using mathematical mixture rules for modulus and gel time. Unlike the non-extruded mixed gels, the extruded mixed gels did not follow the rule for a phase-separated gel type. The changing pattern of gel time with the varying proportion of the two components of the extruded mixed gels was also different than that of the extruded mixed gels. The extrusion specific mechanical energy showed a sudden change at the proportion of the two components where a phase inversion of a phase-separated mixed gel occurs. The polydispersity index (Mw/Mn) determined by gel permeation chromatography system suggested that the extruded agar underwent some structural changes. Extrusion is one of the more versatile bioprocessing technologies, and it is effective in converting food materials in the physicochemical properties. This study attempted to modify the mixed gel properties using the extrusion process. The findings revealed that the extrusion process caused a change in the mixed gel type of κ-carrageenan/agar, shifting from a phase-separated gel to another gel type without phase inversion. This difference can be applied to produce a new mixed gel product.