The physicochemical properties of Korean rice flour cultivars (Saemimyeon [SM], Hanareum No. 4 [HA], and Milyang No. 328 [MY]) with different amylose contents were analyzed and the effects of rice flour blending on their physicochemical property changes were investigated in this study. The swelling power of three different cultivars was similar at 60oC, but MY showed significantly enhanced swelling power at 80oC compared to SM and HA. In the pasting profile, MY showed significantly lower final and break-down viscosities than SM and HA due to its weak granular rigidity. In the case of the 1:1 blending of SM-MY and HA-MY, the measured values of swelling power and solubility were greatly decreased at 80oC, and the setback and final viscosity were significantly increased compared to their predicted arithmetic average values, showing the non-additive effects of blending. For the dynamic viscoelastic properties, SM-MY and HA-MY showed significantly decreased G’ and increased k’ and tanδ, compared to their predicted average values. In conclusion, the selected rice flour blends had non-additive effects on swelling power, solubility, pasting, and dynamic viscoelastic properties. These results showed the feasibility of the rice flour blending to diversify the physicochemical properties of rice flour for better processing suitability.

Vitamin A, particularly all-trans retinol is excellent for anti-aging but is sensitive to oxygen, heat and light and has low solubility in water. In this study, retinol was encapsulated within oil-in-water (O/W) emulsion, protein-based particle and cycloamylose(CA). And then, it confirms that retinol contained in each delivery system is stable to UV, pH, and temperature and finally measures bioaccessibility. O/W emulsion was compared according to the type and concentration of emulsifier. UV stability of retinol increased with increasing oil concentration. More than 10 wt% of oil was required to maintain stable retinol (50% residual after 24 hours of irradiation). Using anionic emulsifier, retinol had unstable storage stability regardless of oil concentration and temperature. Protein based particle was compared according to the type of stabilizer and polysaccharide. UV stability of retinol was highest in pectin-coated particles. However, 20% retinol remains after 6 hours of irradiation and is vulnerable to UV compared to other delivery systems. In pH stability, pectin-coated particles also stably retained retinol. Inclusion complex of retinol and CA was compared according to the concentration of CA. When CA was used, the residual amount of retinol to UV was high (50% residual after 24 hours of irradiation) regardless of the concentration of the host molecule. In the case of storage stability, retinol remained significantly higher regardless of temperature when cycloamylose was used. It was finally confirmed bioaccessibility each of retinol delivery system. O/W emulsion was determined by emulsifier type, protein-based particle by coating agent, and inclusion complex by CA concentration. All O / W emulsions retained more than 50% retinol, protein based particles retained more than 80% retinol, and inclusion complex retained more than 70% retinol. The bioaccessibility of pure retinol is about 20%. This study provides important information for designing effective delivery systems for improving the stability of retinol.

Rice starch is a natural source of polysaccharides that can be used as a stabilizer, thickener, binder and fat mimetic in various foods. However, untreated starch possesses limited functionality due to its poor water solubility with a densely packed granular structure of amylopectin and amylose chains. Also, it shows weak complexing ability as the only amylose participates in complex formation with a chemical compound. The objective of this study is to improve complexation ability and water solubility of rice starch by 4-α-glucanotransferase (4αGTase) treatment. Complex forming capacity was examined by fully dissolving the 4αGTase-treated rice starch in 90% DMSO by mechanical stirring and mixing with iodine solution with following UV/Vis spectrophotometer measurements. Water solubility of the starch was measured by dissolving in distilled water (5% w/v) with mechanical stirring at 25 °C and 60 °C, and drying the supernatant after centrifugation. The complexing ability of starch was enhanced after the 4αGTase treatment. The absorbance at a peak wavelength increased, as well as the peak wavelength was shifted leftward, indicating that the type of molecules got involved in the complexation was changed. Alteration in the molecule composition and starch composition during the enzyme treatment may be due to disproportionation and cyclization by the 4αGTase. The water solubility (%) of the starch at 25 °C and 60 °C increased by 28-fold with the 4αGTase treatment regardless of the treatment time. The untreated starch showed solubility of 0.15 %, while the solubility of the 4αGTase-treated starch was about 4 - 4.5 % (w/v). It may be due to heat treatment and recrystallization which melted a granular structure and made it easier to be solubilized in water. Moreover, the increased solubility might be attributed to increase in the number of short branched chains and decrease in molecular weight.

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.

Different strategies are studied to incorporate lipid-soluble bioactive molecules into water-based food systems. However, these systems solely cannot protect the core compound through the storage period, especially when the core is exposed to environmental stress factors. Water soluble fraction of the crude extract from Enteromorpha prolifera was analyzed for its physicochemical characteristics including chemical composition, structure, rheological and thermal properties. The extract was added to O/W emulsion system containing retinol and stabilized with Tween 20, WPI and sodium caseinate to improve storage stability through different modes of action; as a chelator of metal ions and as a scavenger of radicals. Storage stability was mainly determined by zeta potential, particle size distribution, and retinol retention. The water-soluble extract of E.prolifera mainly consisted of anionic polysaccharide, while impurities of protein, mineral and other pigments were present. Mode of action analysis showed that the extracts had both ferrous ion chelating ability(EC50=0.67%) and free radical scavenging ability(EC50=0.23%), indicating a multifunctioning mechanism of the heterogeneous extract. Addition of extract (0.1%~1% in total emulsion) did not affect the physical stability during 1 week storage. Protective materials are often added to food systems to improve the stability of core materials but excessive use of additives may be repulsive to consumers. In contrast, the optimum concentration range of E.prolifera extract is much lower compared to that of conventional usage of other materials and has lower toxicity to that of strong chelators while providing effective protection.

Curcumin is an active polyphenolic compound with antioxidant, anti-inflammatory and antitumor properties. Curcumin, however, is highly unstable under physiological conditions due to its low stability in acidic and alkaline conditions. Therefore, the objective of this study was to investigate the effects of enzyme-treated rice starch as a wall material on the stability of curcumin in oil-in-water emulsion under different pH conditions. The rice starch was treated using 4-a-glucanotransferase for different time periods and their molecular weight distribution was measured by HPSEC. Curcumin was encapsulated within lipid droplets of O/W emulsion prepared with Tween 20 and the modified rice starch in the aqueous phase at different concentrations (0, 2.5, 7.5 and 10 wt%). The temperature and pH stability of the system were determined respectively by measuring particle size, zeta potential and retention of the curcumin loaded in the emulsion after one-week storage in the solutions with different pH and temperature conditions. The average molecular weight of the modified starch decreased with treatment time. The 96h treated rice starch had the lowest molecular weight while the 1h treated starch mainly consisted of high molecular weight components. The storage temperature did not significantly influence the stability of curcumin emulsion. However, the particle size of the emulsion with modified starch slightly increased when stored at acidic pH condition, which might be attributed to starch aggregation. The curcumin retention was higher for the samples with the modified starch than the control at all concentrations. The pH stability of the curcumin was also higher than the control at all pH conditions. Specifically, the 1h treated starch showed the best performance regarding curcumin protection in emulsion, which might be attributed to the high viscosity that retarded the curcumin release. Further research needs to be conducted on the mechanism.

O/W emulsion is usually adopted to incorporate lipid-soluble bioactive molecules into water-based food systems. However, the emulsion system solely cannot protect the core compound through the storage period, especially in cases when the core is unstable to environmental stress factors. Wall materials such as maltodexrin and chelators such as EDTA-Na are added to improve the stability of core materials but excessive use of additives may be repulsive to consumers. In this study, water soluble fraction of the crude polysaccharide extracted from Enteromorpha prolifera, a type of green algae commonly found in the southern coast of Korean sea, was added to an O/W emulsion system containing retinol to improve storage stability through different modes of action; as a chelator of metal ions, as a scavenger of free radicals and as a wall material. The radical scavenging ability and chelating ability of E.prolifera polysaccharide were determined in solution state. Particle size, zeta potential and retinol retention rate were measured as stability markers in emulsion. Emulsion stability increased and then decreased as the amount of polysaccharide increased from 1 to 5 mg. This optimum concentration is much lower compared to that of conventional usage of wall materials, therefore less affecting the physical characteristics of emulsion while providing effective protection.