Nano-emulsions are emulsions with droplet sizes from 20 nm up to 200-500 nm, thermodynamically unstable, and appear transparent or translucent to the naked eye. Nano-emulsions are very useful in many industries; such as food, pharmaceutical, cosmetic, and chemical. Forming nano-emulsions using a method that requires energy input from a mechanical device is known as a ‘high-energy method’, while a method using chemical energy stored in the components is referred to as a ‘low- energy method’. The low-energy method can be classified into three categories: the Phase Inversion Temperature method, Phase Inversion Composition method or Emulsion Inversion Point method and the Spontaneous Emulsification method. To study nano-emulsification using the low-energy methods, phase diagrams are used to determine the phase behavior of the components and specify the temperature and concentrations at which various structures exist at equilibrium with desired properties. Most research focuses on droplet size and polydispersibility of nano-emulsions, because these properties influence physicochemical properties, appearance and stability of nano-emulsions. There have been many studies on the effect of composition and the major determining factors in the emulsification process on droplet size and polydispersibility of nano-emulsions such as surfactant type, concentration, location, oil type, surfactant-to-oil ratio, salt, stirring speed, and temperature.

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A simple method was developed for determination of the oil content in spray-dried microcapsules by dissolving the microcapsules in N,N-dimethylformamide (DMF). Powders containing flaxseed or fish oils were prepared by homogenization and subsequent spray drying to form coarse and fine emulsions. Sodium caseinate (SC) and maltodextrin (MD) were used as an emulsifier and wall material, respectively. The oil contents in the powders were quantified using a thin-layer chromatography-flame ionization detector after hexane extraction; the results agreed well with the initial oil contents on a dry basis in the feed emulsion, regardless of the oil-droplet size in the powders. The fatty acid compositions of the flaxseed and fish oils in the powders were obtained without an extraction process, using the proposed method. After dissolving the microcapsules in DMF, the peroxide value (POV) of the encapsulated oil was determined using the acetic acid- chloroform method. Although SC, MD, and DMF slightly increased the POV, the effect of the increase on the POV was not significant. The proposed method therefore enables easy and rapid estimation of the oil content, fatty acid composition, and POV of an encapsulated oil.

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The optimal conditions for the synthesis of lauroyl erythorbate through the condensation of erythorbic acid with lauric acid using immobilized lipase in organic solvents were determined, which are as follows: 0.5 mmol of erythorbic acid, 3.75 mmol of lauric acid, 5 mL of acetonitrile, 50 mg of Chirazyme^® L-2 C2, 60°C. Octanoic, decanoic, myristic, and palmitic acid were also used for the synthesis of acyl erythorbate; however, the effect of the acyl chain length of the fatty acid on the reaction conversion was not observed. The DPPH radical scavenging activities of erythorbic acid and acyl erythorbates were measured and it was indicated there was no difference in the activity between erythorbic acid and acyl erythorbates in ethanol solution. Additionally, the suppressive ability of acyl erythorbate against lipid oxidation was investigated. Palmitoyl erythorbate significantly improved the oxidative stability of methyl linoleate to the same extent as that of palmitoyl ascorbate. Based on these results, acyl erythorbate could be considered to be a useful food additive as an amphiphilic antioxidant in a food system such as lipid microcapsules.

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We studied the applicability of our colorimetric monosaccharide assay based on the direct molybdosilicate reduction (DMoR) to evaluate saccharification reaction to produces glucose. DMoR method is simpler than conventional method which used chromatographic or enzymatic reaction method. The method comprises mixing a molybdosilicate solution with sample, and heating the mixture, in which the yellow molybdosilicate species is reduced directly by the monosaccharide to blue heteroplyanion. Thus, glucose gave the color change of the mixture depending on its concentration. On the other hand, maltose and cellobiose and starch showed no significant color change at the same concentration level. This present method was applied to determination of the glucose in the enzymatic reaction mixture of water-soluble starch and the extracts from sweet potato with glucoamylase. This present colorimetric results were good agreement with those by conventional electrochemical technique.

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Flow cytometry (FCM) and aerobic plate count (APC) by the culture method were performed on green tea samples spiked with Escherichia coli type strain NCTC 9001 solutions of different concentrations. In FCM, fluorescence signals from multiple stained bacteria and other fluorophores were detected using detector channels A, B and C, and recorded as events with a voltage at each channel. As a conventional FCM, the number of events with voltage larger than the threshold values at channels A and C with zero voltage at the channel B, which corresponded only to dead cells, was regarded as the predicted APC. In addition, voltage histograms of channels A and C were developed with the optimized bin width and merged horizontally. Then partial least squares regression (PLSR) was applied to the histogram data to develop a calibration curve by which APC could be predicted. The root mean square error (RMSE) between measured APC and that predicted by conventional FCM was 1.09-1.15 [log10 cfu/ml]. The APC predicted by the PLSR and that measured were in good agreement with RMSE of 0.51 [log10 cfu/ml], which verified the potential of the proposed method for the accurate APC prediction by FCM.

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In order to establish the industrial production of difructose anhydride III (DFA III) from inulin using subcritical water, we investigated the effect of subcritical water phases (5 preset temperature: 150, 155, 160, 165, 170℃ , pressure: 3.0-5.0 MPa) on hydrolysis of inulin. The inulin hydrolyzate components determined by mass spectrometry were difructose anhydrides (DFAs) including DFA III, monosaccharides and oligosaccharides with degrees of polymerization (DPs) of 2-12. The DPs of oligosaccharides prepared at 165 and 170℃ were 2-4 and those at 150, 155 and 160℃ were 2-12. Hydroxymethylfurfural (HMF) and furfural were also detected in the inulin hydrolyzate by UV-Vis spectrometry. The optimum temperature for converting inulin to DFA III was temperature of 160-165℃ , pressure of 3.0-5.0 MPa. This study showed a potential of formation of DFA III from inulin under these subcritical water phases.

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This study reports on the reduction of moisture absorption of amorphous rice flour formed by ball milling. Ball milling has been applied to starch for conversion of its physico-chemical properties. Ball milling converts the semi-crystalline state of starch to an amorphous state, and the prolonged procedure promotes enthalpy relaxation. It has been reported that prolonged treatment leads to an decrease in starch water sorption. However, because the size of the ball mill container was small in a previous study, it was not suited for industrial applications. In the present study, a vibrated type ball milling with a large container of rice was carried out for up to 9hr. The confirmation of crystalline was evaluated by using the X-ray diffractometry. The relaxed enthalpy (ΔH) was measured by differential scanning calorimetry. Water sorption isotherms were measured by equilibrium sorption of water vapor. With the milling time, enthalpy relaxation was found to increase and water sorption to decrease. The sorption isotherms were analyzed with a dual mode sorption model, and the concentration, C’_H, of Langmuir type sorption site was found to decrease with the time. In the present study, the ball milling was to improve the adsorption properties of rice flour, that regardless of the size of the ball mill container, it has been found that it is possible to create an amorphous rice flour with physicochemical properties.

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Effects of pre-drying treatments such as blanching and dipping (soaking) in a sucrose solution on browning of lemon peel during drying were investigated. A color analysis method using a digital camera and computer software based on the HSL color system was employed for determination of the degree of browning of lemon peels. Hue (H) value decreased as the browning increased. Other two parameters, saturation (S) and lightness (L), were not sensitive to the browning reaction monitoring. The browning rate was faster at the beginning of the drying and became slower when the water content became low. The pre-treatments resulted in less browning during drying. In order to examine the browning rate as a function of water content, the samples of different water contents were incubated in an airtight container (no water loss during incubation), and the H values were determined as a function of incubation time. The browning became faster when the water content was high. Sample pre-treatments such as blanching and dipping in a sucrose solution slowed down the browning rate compared with non-pre-treated samples. The browning during drying was significant when the air temperature was above 318K. The pre-drying treatments (blanching and soaking in a sucrose solution) resulted in much slower browning.

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The surface-oil contents of microcapsules with differing oil droplet-to-microcapsule size ratios were estimated based on a two-dimensional percolation model to examine the effects of differences in the ratio distribution. In the model, squares were divided into equal lattices that were sized to obey a log-normal distribution. The surface-oil contents of microcapsules with various volumetric oil fraction and different variances of the ratio were evaluated. The variance in the distribution of the oil droplet-to-microcapsule size ratio had no significant effect on the surface-oil content at any oil fraction in the microcapsules.

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