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EFFECTS OF EXTRUSION ON κ ‐CARRAGEENAN/AGAR MIXED GEL TYPE
Author(s) -
KIM KEEHYUK,
LEE SEUNG JU
Publication year - 2009
Publication title -
journal of texture studies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.593
H-Index - 54
eISSN - 1745-4603
pISSN - 0022-4901
DOI - 10.1111/j.1745-4603.2009.00203.x
Subject(s) - extrusion , agar gel , carrageenan , phase inversion , materials science , gel permeation chromatography , agar , chromatography , dispersity , chemical engineering , rheology , chemistry , composite material , polymer , polymer chemistry , food science , membrane , biochemistry , genetics , microbiology and biotechnology , bacteria , engineering , biology
κ ‐Carrageenan and agar have a slight mutual thermodynamic incompatibility. Therefore, this study examined the effects of extrusion on the synergy of κ ‐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 ( M w / M n ) determined by gel permeation chromatography system suggested that the extruded agar underwent some structural changes.PRACTICAL APPLICATIONS 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.