Coconut oil was purchased from the local market. Skimmed milk powder (SMP, 36% protein content), guar gum and carboxymethylcellulose were supplied by the China Mengniu Dairy (Inner Mongolia, China). 1-Anilinonaphthalene-8-sulfonate (ANS), fluorescein isothiocyanate (FITC) and Nile red were obtained from Sigma–Aldrich Chemical Co. Ltd. (St. Louis, USA). All other reagents were of analytical grade