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.

The relationship of in vitro starch digestibility and gel strength was investigated at various concentrations (10-30%) of rice cultivars with different amylose contents (27.9, 17.9, and 5.2%). As the rice flour concentration increased, predicted glycemic index decreased, but gel strength increased regardless of amylose contents. Gel strength correlated strongly with amylose content, whereas in vitro starch digestibility was more highly affected by rice flour concentration than by amylose contents. Moreover, the impact of degree of gelatinization on in vitro starch digestibility of high amylose rice was also examined in terms of structural features and rheological properties. The digestion rate of fully gelatinized flour was 1.7 times higher than that of native flour, while the disrupted structure with a different gelatinization degree during starch digestion was visually demonstrated through the X-ray diffraction and molecular distribution analysis. The rice flour changed from an A-type to a V-type pattern and showed difference in crystalline melting. The low molecular weight distribution increased with increasing degree of gelatinization during starch digestion. The apparent viscosity also increased with degree of gelatinization. These results demonstrated that the starch digestibility of rice was more affected by concentration than by amylose content, as well as by the degree of gelatinization due to structural difference.

In-vitro food mastication has been simulated by incorporating size reduction process, followed by incubation with human saliva. However, they do not suffice to simulate the actual oral breakdown process where disruption by mastication (chewing) and wetting/lubrication by salivation take place simultaneously. In this study, in-vitro oral digestion of rice gels with different amylose contents was simulated by instrumentally performing mastication and salivation. The hardness of artificial saliva-treated rice gels was distinctly lowered with increasing chewing cycles and the rice gels with high amylose contents showed the highest degradation rate. When the rice gels were subjected to non-destructive tomographic analysis, the high amylose rice gels were clearly shown to be favorably fragmented into smaller pieces by chewing, followed by the low and intermediate amylose samples. These results could be explained by their cohesive texture rather than hardness. Therefore, this study may help understanding the changes in the physical properties of cereal-based foods during oral digestion.

Vitamin A is essential for growth and differentiation of a number of cells and tissues, as result the precursor, a carotenoid β-carotene remains their essential source of vitamin A. However, the major problem this carotenoid face, is its susceptible to photodegradation and chemical oxidation, those properties make it difficult to use as an ingredient as functional food product and reduce its bioavailability. This study presents a novel approach to prepare a one-step inclusion complex using amylose microparticles as host molecule using amylosucrase from Deinococcus geothermalis (DGAS) and β-carotene nanoparticles, which were added into the DGAS enzyme reaction solution to entrap them during the synthesis of amylose chains. HRFE-SEM showing a spherical shape and average diameter of 4-8 μm; XRD and DSC showed an amorphous structure as well as less energy required to start the gelatinization process, due to the complexation of amylose chains with the β-carotene nano dispersion. Last but not least Raman spectroscopy was performed in order to confirmed the complex formation between β-carotene and amylose microparticles, showing the characteristic peaks of both compound. The stability test in this study showed the high stability of the complexed microparticles against environmental stresses such as, photodegradation and chemical oxidation. We expect this study contributes to the development of functional food materials to enhance the stability and bioavailability of active compounds.

Heavy metals are typical contaminant in water and need to be removed because they are non-biodegradable and can accumulate in human body. To remove metal and other contaminants from water, chemical absorbents are widely used due to their low cost. Herein, hybrid materials comprised of amylose and single wall carbon-nanotube (swCNT) was developed as the absorbent for water purification. A high adsorption properties of carbon-nanotubes have been utilized in designing effective absorbent but its poor dispersity in water is a limiting factor for practical use. Single wall carbon-nanotube was hybridized with amylose chain produced by enzyme reaction of amylosucrase and their tendency to self-assemble in aqueous environment. The amylose-swCNT microparticles were characterized by FE-SEM and turned out to be spherical structure with CNTs embedded throughout the amylose matrix. The ability of amylose-CNT microparticles to remove copper was examined. Concentration of copper was decreased after reaction with amylose-swCNT microparticles. Although amount of decreasing copper was less than swCNT on same total mass, Adsorption efficiency of amylose-swCNT microparticles was good because their swCNT content was only 10% of total mass.

We developed a Amylose magnetic beads (AMBs) based detection system for high efficient separation, concentration and detection of E. coli O157:H7 in real sample. AMBs were synthesized by amylosucrase from Deinococcus geothermalis (DgAS) with iron-oxide nanoparticle (NP). The design of amylose magnetic beads (AMBs) have studied by an enzymatic synthesis with optimized reaction condition such as substrate, sucrose, and iron-oxide NP. AMBs have specific feature. AMBs decorated with functional fusion protein, which consists in a maltose binding protein (MBP) and a streptococcal protein G (SPG). Amylose chains has maltose, thus MBP-SPG binds to the AMB. In addition, SPG specifically binds to the Fc part of antibody. That was used as a linker to immobilize antibody to the surface of AMBs. The resulting AMBs were efficiently separated and concentrated target bacteria, E. coli O157:H7. Concentrated sample is qualitatively analyzed by PCR. Our studies demonstrated that AMB-based PCR significantly reduced the limitation of detection as low as 10 1 CFU/mL, compared to that of conventional PCR. The principle of this system can be served as a high efficiency for detection method of any pathogenic bacteria. In addition, AMBs and MBP-SPG cross-linker protein developed in this study is expected to be applicable to the portable food based biological processing monitoring system.

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.

As one of the staple crops, rice has been widely applied to value-added products, giving the food industry new avenues of use. Although the quality attributes of various rice products have been reported, there is a lack of detailed information on the rheological behaviors of rice products during digestion that are related to their bioaccessibility in the human body. In this study, three rice varieties with different amylose contents were utilized to produce flours and extruded noodles. In-vitro methods simulating starch digestion processes were then established to monitor their oral-gastric-intestinal rheological behaviors. The rice flour with high amylose content exhibited lower values of water absorption index/swelling power and higher pasting parameters that were in good agreement with the Mixolab thermo-mechanical results. The extruded rice noodles showed lower cooking loss and higher hardness with increasing levels of amylose. When the in-vitro viscosities of rice flours and noodles were measured using a rotational rheometer with the custom-made starch cell, their viscosities had a tendency to decrease as the in-vitro digestion progressed. Specifically, the rice samples with high amylose content exhibited higher viscosity than those with low amylose content under the simulated oral, gastric, and intestinal conditions. Hence, this study was conducted to investigate the physicochemical and in-vitro rheological properties of rice flours and extruded noodles with different amylose content. The results provided a promising opportunity for the food industry to study in-vitro digestion of rice-based products with the advantages of being more rapid and less expensive.

국내에서 생산되어 시판되고 있는 보리쌀 제품을 수집하여아밀로오스와 β-glucan 함량을 분석하고 아밀로오스 함량에 따른 찰성 및 메성 보리쌀의 호화 및 취반 특성을 비교하였다.보리쌀 제품은 제품에 표기된 바에 따라 찰보리쌀과 메보리쌀로 분류하여 이들의 아밀로오스 함량을 측정하였다. 분석결과보리쌀 제품의 아밀로오스 함량은 4.46 ~ 30.68% (평균 16.33%)로 다양하게 나타났으며, 찰보리쌀 제품은 대부분 아밀로오스함량이 5 ~ 10% 정도의 분포를 보였다. 보리쌀 제품의 β-glucan 함량은 2.49 ~ 6.79% 범위(평균 4.57%)로 분석되었다.시판 보리쌀 제품을 찰보리쌀(아밀로오스 10% 이하)과 메보리쌀(아밀로오스 20% 이상) 그룹으로 구분하여 각각 선발한보리쌀 제품을 비교하였으며, 찰보리쌀이 메보리쌀에 비해 β-glucan 함량이 약 2% 높게 나타났다. 찰보리쌀은 메보리쌀에비해 신속점도측정기(RVA)에 의한 호화개시온도, 최고점도,trough, breakdown, 최종점도, setback이 낮게 나타났다. 보리쌀의 취반특성에서 시판 찰보리쌀은 메보리쌀에 비해 수분흡수율과 퍼짐성은 높은 반면 용출고형분이 낮았으며, 텍스쳐(경도)는 찰보리쌀이 낮아 보리밥의 취반특성 및 식감이 보다 좋은 것으로 평가되었다.

The objective of this study was to determine the physico-chemical properties in the high-amylose rice varieties. The rice flours were analyzed by RVA, DSC, HPAEC, resistant starch kit, SEM, spectrophotometer, etc. According to the RVA measurement of rice flours, the pasting temperature of Dodamssal was higher than those of the others. The proportion of amylopectin short chains (DP 6-12) of the Dodamssal was significantly lower than that of the others. The contents of amylose and resistant starch in the high-amylose rice flours ranged from 19.03% to 38.71% and from 0.6% to 12.39%, respectively. In SEM images, starch granules within Ilmibyeo, Mimyeon, Saegoami rice flours displayed polyhedrons different from those (relatively spherical morphology) of Dodamssal rice flour. According to the DSC results of rice flours, there were significant differences in the onset, peak temperatures of the endothermic peak. Gelatinization enthalpy was 4.52-6.3 J/g, with the lowest change in Dodamssal rice flour.