Effect of palm-based milk on the rheology of Kappaphycus Alvarezii carrageenan
Sariah Saalah (1*), Noor Ayuni Sahwazni Abdul Samad (1), Suryani Saallah (2), Jumardi Roslan (3), Murni Sundang (1), Mariani Rajin (1), S.M Anisuzzaman (1)

1) Chemical Engineering Programme, Faculty of Engineering, Universiti Malaysia Sabah, 88400 Kota Kinabalu, Sabah, Malaysia
*s_sariah[at]ums.edu.my
2) Biotechnology Research Institute, Universiti Malaysia Sabah, 88400 Kota Kinabalu, Sabah, Malaysia
3) Faculty of Food Science and Nutrition, Universiti Malaysia Sabah, 88400 Kota Kinabalu, Sabah, Malaysia

Abstract

This study examines the compatibility and gelation behavior of carrageenan extracted from Kappaphycus alvarezii in the presence of palm-based milk (PBM). Two types of carrageenan were prepared: semi-refined carrageenan (SRC), obtained via alkali pretreatment, and crude carrageenan (CC). FTIR analysis confirmed both as kappa-carrageenan, with SRC showing stronger characteristic peaks, indicating enhanced structural conversion. PBM alone exhibited shear-thinning behavior, with a viscosity of 13.7 mPa.s at 25 degree Celsius and a shear rate of 100/s. Oscillatory tests assessed the viscoelastic properties of gels containing 10% PBM. Amplitude sweep analysis at 5 degree Celsius showed the linear viscoelastic region (LVER) limits for neat CC and SRC at 0.44% and 0.557%, respectively, which decreased to 0.217% for both upon PBM addition. All samples exhibited solid-like behavior. Temperature sweep tests (96 degree Celsius to 5 degree Celsius, slow cooling) revealed a sharp increase in complex viscosity between 96 degree Celsius and 90 degree Celsius, followed by a relatively steady trend, while maintaining a solid-like state across the measured range. Between 30 degree Celsius and 5 degree Celsius, PBM addition caused only a slight reduction in storage modulus. These results highlight PBM potential as a plant-based alternative to dairy milk in carrageenan-based gelling systems, without compromising gel rheology for food applications.

Keywords: Carrageenan- Palm milk- Rheology- Seaweed

Topic: Food science and biotechnology