Kyung Mi Kim

Digestibility and physicochemical properties of granular sweet potato starch as affected by annealing

The effects of annealing on the digestibility, morphology, and physicochemical characteristics of four types of granular sweet potato starches [Yulmi (YM), Yeonwhangmi (YHM), sweet potato starch from Samyang Genex (SSPS), and commercial sweet potato starch (CSPS)] were investigated. Annealing was performed at 55°C and 90% moisture content for 72 h. Morphology, the branched chain distribution of amylopectin, and the X-ray diffraction pattern remained unchanged during the annealing process. The slowly digestible starch content in annealed YM, YHM, and SSPS starches increased, but did not change in annealed CSPS. The gelatinization temperatures increased, but the gelatinization temperature range decreased with annealing. The swelling factor and amylose leaching decreased, while the close packing concentration increased. Rapid Visco Analyser analysis revealed that annealed starches possessed thermal stability and higher pasting temperatures. It is suggested that the enhanced packing arrangement formed during annealing impacts the digestibility and physicochemical properties of sweet potato starches.

Slowly digestible sweetpotato flour: Preparation by heat-moisture treatment and characterization of physicochemical properties

The preparation and physicochemical characteristics of sweetpotato flour with increased slowly digestible starch (SDS) fraction were investigated under various heat-moisture treatment (HMT) conditions. The optimum conditions for preparing slowly digestible sweetpotato flour established using response surface methodology were moisture content of 22%, temperature of 103°C, and treatment time of 5.8 h. The highest SDS content in heat-moisture treated sweetpotato flour was 57.6%. The relative crystallinity of heat-moisture treated sweetpotato flour decreased, but the X-ray diffraction pattern maintained the A-type. The DSC of the heatmoisture treated flour showed a decreased gelatinization temperature range and gelatinization enthalpy compared with native one. The viscosity profiles and values changed significantly with HMT, resulting in a higher pasting temperature, decrease of the viscosity values, and no breakdown. It indicates that heat-moisture treated sweetpotato flour is more stable at high temperatures and shear rates than native one.

Free and bound form bioactive compound profiles in germinated black soybean (Glycine max L.)

This study investigated the transition between the free and bound forms of functional compounds in germinated black soybean. Black soybean was germinated at 25°C over 6 days and then the free and bound forms of functional compounds were extracted. Total free polyphenol, flavonoid, and phenolic acid contents in raw black soybean increased from 1.03 mg GAE/g, 0.29 mg CE/g, and 315.67 μg/g to 1.44mg GAE/g, 0.64mg CE/g, and 511.01 μg/g, respectively, by 4 days after germination. Changes to phenolic acid compositions can be divided into four groups, and the germination process can convert compounds to phenolic acid via anabolism and catabolism. The highest total free isoflavone content in germinated black soybean (3,724.40 μg/g) was observed at 4 days. Bound polyphenol, flavonoid, phenolic acid, and isoflavone contents decreased as the germination period increased. These results suggest that the germination process increased compound functionality in black soybean.

Characterization of Korean Sweet Potato Starches: Physicochemical, Pasting, and Digestion Properties

Physicochemical, pasting, and digestion properties of sweet potato starches from 11 Korean cultivars were investigated. Starch granules were variably oval, round, polygonal, spherical, and bell-shaped, and of 10.2-15.3 µm in mean particle diameter. Amylose contents varied from 12.3 to 17.4%. A similar chain length distribution of amylopectin was found in each of the cultivars. The portion of B3 correlated with the degree of amylose leaching. Thermal properties determined by differential scanning calorimetry showed high values of gelatinization temperatures in Shinyulmi and Jeungmi starches, but a relatively low value in Daeyumi starch. All starches exhibited a Ca-type diffraction pattern. Differing patterns were observed in swelling factors, depending on temperature. The contents of rapidly digestible starch, slowly digestible starch, and resistant starch ranged from 9.6-17.4, 31.4-45.6, and 35.7-62.8%, respectively. In Rapid Visco Analyser profiles, differences were observed in pasting parameters such as pasting temperature, peak viscosity, final viscosity, and breakdown.Physicochemical, pasting, and digestion properties of sweet potato starches from 11 Korean cultivars were investigated. Starch granules were variably oval, round, polygonal, spherical, and bell-shaped, and of 10.2-15.3 μm in mean particle diameter. Amylose contents varied from 12.3 to 17.4%. A similar chain length distribution of amylopectin was found in each of the cultivars. The portion of B3 correlated with the degree of amylose leaching. Thermal properties determined by differential scanning calorimetry showed high values of gelatinization temperatures in Shinyulmi and Jeungmi starches, but a relatively low value in Daeyumi starch. All starches exhibited a Ca-type diffraction pattern. Differing patterns were observed in swelling factors, depending on temperature. The contents of rapidly digestible starch, slowly digestible starch, and resistant starch ranged from 9.6-17.4, 31.4-45.6, and 35.7-62.8%, respectively. In Rapid Visco Analyser profiles, differences were observed in pasting parameters such as pasting temperature, peak viscosity, final viscosity, and breakdown.

Effects of Steeping Temperatures and Periods of Waxy Rice on Expansion Properties of Gangjung (a traditional Korean oil-puffed rice snack)

ABSTRACT This study was conducted to investigate the effect of steeping conditions of waxy rice, temperatures (15, 25, and 35°C) and time periods (1, 11, and 21 days) on the expansion ratio of gangjung (a traditional Korean oil-puffed rice snack). Physicochemical properties of waxy rice flour steeped under various conditions and expansion properties of gangjung made of the steeped waxy rice flour were investigated, and multiple regression analyses were applied between those properties to identify major physicochemical factors that optimally predict the expansion ratio of gangjung. As steeping temperature and time periods of waxy rice changed from the lowest to the highest, the expansion ratio of gangjung markedly increased (from 1,022 to 2,533%). Yet, the expansion ratio of the waxy rice sample steeped for 11–21 days at 35°C was not significantly different from the sample steeped for 21 days at 25°C, indicating that the lengthy steeping process for gangjung making can be shortened by increasing the steepi...

Effect of Packaging on Quality of Stored Gangjung

Haeng Ran Kim*, Dong Sun Shin, Kyung Mi Kim, Sun Mi Yu, and Jin Sook KimDepartment of Agrofood Resources, National Academy of Agricultural Science, RDAAbstract This study was conducted to improve the packaging technology used for Gangjung and the product’s qualitycharacteristics during storage. Packaging materials consisting of (1) IP: OPP (oriented polypropylene)/PE (polyethylene) +Paper, (2) LP1: OPP/PE + Paper, (3) LP2: OPP/PE + Can, (4) LP3: OPP/PE + Plastic, (5) BP1: OPP/PE, (6) BP2: OPP/DL/CPP (cast polypropylene), (7) BP3: PET/PE/CPP, and (8) BP4: OPP/PVDC (polyvinylidene chloride)/PE/CPP wereused. The major fatty acids including 54.2% linoleic acid, 24.1% oleic acid, 11.2% palmitic acid and 6.0% linoleic acidwere assessed. The packages effective in maintaining moisture were in the order of LP2, BP4 > IP > LP3, BP1,BP2 > LP1 > BP3. There were no significant differences in water content and the products in IP, BP3, and BP showed thehighest level in the increase in hardness on day 60 of storage. Acid values of IP, LP1, LP2, LP3, BP1, and BP2 weremaintained at <2.0 during 40 days of storage. IP, LP1, LP2 and BP1 had the below of 40 in and peroxide during 20 days.Keywords: packaging, Gangjung, quality characteristics, storage

Physicochemical properties of enzyme-treated waxy rice flour and expansion properties of Gangjung (a traditional Korean oil-puffed rice snack)

Long steeping process of waxy rice involved in Gangjung production is essential for obtaining good quality Gangjung, but it causes many related problems. The objective was to examine physiochemical properties of waxy rice flour and expansion properties of Gangjung manufactured using waxy rice flour treated with protease (P-flour), α-amylase (A-flour), or in combination of the two (PA-flour) over different durations. While crude protein and reducing sugar contents of P-flour and Aflour differed depending on enzyme treatment time, it was not observed for PA-flour. Gangjung made with P-flour or A-flour could show similar expansion rate to that of Gangjung made with waxy rice flour steeped under the optimal condition, however, Gangjung made with PA-flour showed lower expansion rate than of the optimal one. These findings indicate that treatment of waxy rice flour with either protease or α-amylase, but not both, could reduce the steeping time involved in Gangjung production.

Preparation of black soybean (Glycine max L) extract with enhanced levels of phenolic compound and estrogenic activity using high hydrostatic pressure and pre-germination

ABSTRACT We investigated the influence of high hydrostatic pressure (HHP) treatment on the estrogenic properties and conversion of the phenolic compounds in germinated black soybean. The black soybean was germinated for two- or four-days, and then subjected to HHP at 0.1, 50, 100, or 150u2005MPa for 12 or 24u2005h. The highest total polyphenol content (3.9u2005mg GAE/g), flavonoid content (0.8u2005mgu2005CE/g), phenolic acid content (940u2009±u200918.96u2005μg/g), and isoflavonone content (2600u2005μg/g) were observed after germination for four days and HHP treatment at 100u2005MPa for 24u2005h. In terms of isoflavone composition, the malonyl, acetyl and β-glycoside contents decreased, while the aglycone content increased with HHP. The highest proliferative effect (150%) is observed at four days germination and HHP treatment at 100u2005MPa. These results suggest that application of HHP may provide useful information regarding the utility of black soybean as alternative hormone replacement therapy.

Behavior of Retrogradation Retardation in Rice Starch Paste by Raw Wheat Flour Addition

The effect of raw wheat flour on starch retrogradation retardation was investigated in a rice starch paste model. Specifically, in terms of amylase activity present in the wheat flour, the retardation effect was investigated depending on reaction temperature (40, 60, and 80 o C), incubation time (0, 20, 40, and 60 min), and wheat flour addition levels (0-10%). An increase in wheat flour concentration resulted in a rapid decrease in the elastic modulus (G) as the incubation time increased. The G changes of the rice starch pastes were furthermore fitted by the first order reaction for the reaction rate estimation on the temperature basis. The experimental reaction rate of the paste sample incubated with 10% wheat flour at 40 o C exhibited good agreement with the predicted value. This result implied that the first order reaction kinetics could

Changes in volatile compounds of waxy rice and gangjeong (a traditional Korean oil-puffed snack) under different steeping conditions

Effects of steeping temperature (15, 25, and 35°C) and steeping period (1, 11, and 21 days) on volatile compounds isolated from waxy rice and gangjeong made using steeped waxy rice were evaluated. Six acids, 4 alcohols, 2 carbonyls, 1 furan, and 2 hydrocarbons were detected in waxy rice. Acids and alcohols accounted for the majority of isolated compounds. Compositions of volatile compounds differed according to steeping temperature and time, probably due to changes in microorganisms and enzymes. Forty volatile compounds were isolated from gangjeong made using steeped waxy rice, including 3 acids, 7 alcohols, 10 carbonyls, 1 furan, 10 terpene hydrocarbons, 5 aliphatic hydrocarbons, 2 sulfur-containing compounds, and 2 miscellaneous compounds. Most volatiles were generated via lipid oxidation and decomposition. 2-Pentyl furan was the major volatile compound in gangjeong. Volatile aroma compounds from waxy rice and gangjeong made using steeped waxy rice varied according to steeping conditions and frying processes.