Although carnosic acid (CaA) is known as one of the useful polyphenolic compounds due to its antimicrobial and antioxidant activities, it is limited to use as aqueous solution because of its low solubility and unstability. The objective of this study was to investigate the capability of CA to improve the solubility of CaA by forming an inclusion complex in comparison with cyclodextrin (CD) and maltodextrin (MD). Enzymatically-produced CA was reacted with CaA in aqueous solution to form a complex using a freeze-drying. And the formation of complex between CaA and CA was identified by X-ray diffraction (XRD), differential scanning calorimeter (DSC) and field emission scanning electron microscope (FESEM). As a result of XRD and DSC analysis, disappearance of characteristics of CaA that was reacted with CA could be indicated the complex formation between CaA and CA. The formation complex of CaA with CA was also confirmed through the change in morphology of CaA and CA in the electron micrograph result. Aqueous solubility of CaA with various concentrations (1, 5, 10, 20, 30%) of CA was measured by absorbance change at 285 nm. As a result, the solubility of the CaA was significantly increased with increasing CA concentration. At 30% CA, the maximum solubility of CaA was 0.095% (w/v) in solution, which was approximately 3 times higher than that of free CaA (0.033%). The effect of inclusion complex with CA on the solubility of CaA was superior than that with CD (0.057%) and MD (0.066%). These results indicated that the effects on the solubility and formation abilities of inclusion complex were associated with host materials and its concentration rate. This study confirmed that the CA can be a viable solution to improve the aqueous solubility of CaA. Further investigation is still needed to understand the effect of inclusion complex with CA.

Production method of cycloamylose (CA) has been developed using native starch as an economically more beneficial substrate than commercial amylose. However, the yield of CA products from starch is lower than that from commercial amylose. Thus, the objective of this study was to improve the yield of CA products using high amylose corn starch (HACS) that has the highest amylose content (approximately 70%) among native starches. The reaction conditions of isoamylase were optimized to maximize debranching yield of HACS. After debranching, CA was produced by the action of Thermusaquaticus 4-α-glucanotransferase (TAαGTase) for various reaction times. Remaining linear glucans were removed by glucoamylase under the optimum conditions. As a result, the maximum conversion yield of CA from HACS was71% that was 2.2-fold higher than that from rice starch (e.g. Ilpummi; 32%). The degree of polymerization (DP) of CA products ranged from 7 to 41, with DP26 showing the highest yield. This DP profile was very similar as that of CA produced using commercial amylose. Also, a significant amount of larger cyclic glucans were produced from HACS, which was not the case for CA from rice starch. These results were attributed to the unique molecular structure of HACS such as high amylose content and long branch chain length. The high yield production of CA from HACS could be beneficial for industrial applications.