Carnosic acid from rosemary extract is one of the natural phenolic compounds which show the antioxidant and antimicrobial activities. Nevertheless, the use of rosemary extracts in food matrix is highly limited due to the low water solubility and poor chemical stability of active constituents of extract. Therefore, the aim of this study is to investigate the functionality and effect of starch based polymers on rosemary extract in aqueous solution for improving their efficiency of food application. To manufacture the rosemary-starch polymer complex, starch based polymers (cycloamylose; CA, cyclodextrin; CD, hydroxypropyl-beta-cyclodextrin; HP-b-CD, maltodextrin; MD, clustered dextrin; ClusD) were firstly dispersed in 5mM phosphate buffer (pH7) according to each concentrations. Rosemary extract was then dissolved in solution to react with the polymers. Enhanced water solubility of rosemary extract was measured using a spectrophotometer. Antioxidant (ABTS assay) & antimicrobial activity (MIC test) were also tested. In aqueous solution containing CD and HP-b-CD, the solubility of rosemary extract increased almost twice or more (189% and 248% respectively). CA, MD, and ClusD solutions also showed the results of increasing the solubility about 126%~129%. As rosemary extract dissolved better, it was also found to have increased antioxidant and antibacterial activity of rosemary-starch polymer complex. Especially, the degree of antioxidant activity has been increased much larger than the increased solubility level. Consequently, more studies are needed to determine why these results are produced. If further studies and experiments are conducted on this, it could be beneficial for food industry interested in utilizing rosemary extract.

Licorice and rosemary contain a number of natural phenolic compounds which have a strong antibacterial and antioxidant activity. Ulleungdo stonecrop (US, scientific name: Sedum takesimense Nakai), indigenous island, is also known as a good antibiotic agent and skin whitening agent and is regarded as a promising materials in cosmetics field. Although the antibacterial activity of each material have been reported, little is known about the effect of using them together. Therefore, the purpose of this study was to investigate the synergistic effect on antibacterial activity when licorice and rosemary extract and US were used together. Since licorice and rosemary are lipid soluble materials and US is water soluble material, oil in water (O/W) emulsion system was used for this study. To manufacture O/W emulsions containing three kinds materials, first licorice and rosemary extracts and US was dispersed in soy bean oil and phosphate buffer (pH7) respectively. Decaglyceryl laurate was used as an emulsifier. There was slight decrease (-0.09~-0.46 Δlog) in the number of bacteria when O/W emulsion containing 300ppm of each licorice and rosemary extracts was mixed into B.subtilis. However, adding US (2,700ppm) into aqueous phase caused the rapid decrease in the amount of bacteria to -1.71 ~ -2.96 Δlog which were much higher decrement than US only in normal emulsion (-1.64 Δlog). In particular, there was a noticeable synergistic effect when rosemary extract and US was used together. The results obtained from this study could provide useful information for utilizing licorice and rosemary extracts and US as functional materials in the food and cosmetic areas.

Recently, there is a growing interest of consumers in natural products thus a large number of natural preservatives have been studied as food additives. Among those natural preservatives, rosemary extract are commonly used by the food industry to extend the shelf life of several products. Nevertheless, the incorporation of the rosemary extract in food matrix is highly limited due to the low water solubility and poor chemical stability of constituents of rosemary extract. In this context, it is needed to find a way that can improve the water solubility to incorporate rosemary extract into aqueous system like foods. Hence, in this study we added surfactants that have a relatively high hydrophilic-liphophilic balance number into rosemary extract solution to increase the water solubility of rosemary extract and then investigated the microbial activities of rosemary extract with surfactants. Tween 20, decaglycerol monooleate, decaglycerol laurate and decaglycerol myristate were used in a range 0.1~4% and rosemary-surfactant solution was prepared by dissolving rosemary in surfactant added phosphate buffer (pH 7) as much as extract can be dissolved. Water solubility of rosemary-surfactant solution were examined by observance of the UV-vis spectra. The antimicrobial effects rosemary-surfactant solution on B.subtilis were also examined by paper disc diffusion method. Rosemary extract showed poor solubility in normal phosphate buffer but its water solubility was highly increased when surfactant was added. This tendency was lasted at all types of surfactant. This is because of amphipathic property of surfactant. Antimicrobial effect to B.subtilis was observed when a relatively lower concentration of surfactants were used, however, not in high concentrations. This result might be attributed to the formation of surfactant micelles containing rosemary extract when a relatively higher concentration of surfactants were used. The information presented may be useful for the development of a new rosemary-loaded delivery systems.