Kwang-Sup Youn

Optimization of roasting conditions according to antioxidant activity and sensory quality of coffee brews

Response surface methodology (RSM) was used to determine the optimal roasting temperature and roasting time of coffee beans used for preparing brews with high antioxidant activity and sensory quality. Green coffee beans (Coffea arabica L. cv. Colombia Organic Tamata) were roasted at temperatures ranging from 140 to 220°C for 2–10 min and were then brewed with dripping hot water. The effects of the roasting conditions on the browning index, antioxidant activity, color, aroma, taste, and overall acceptability of the coffee brewed from the bean were investigated using a second-order central composite design. The quality indicators except the taste were significantly affected by roasting temperature and time, tending to increase and then decrease with increasing roasting temperature and time. Superimposed contour plots indicated that the optimal roasting temperature was 182°C and optimal roasting time was 7 min.

Effect of Different Pre-treatments on the Physicochemical and Antioxidant Activities of Cold-Vacuum Dried Peaches

This study was performed to determine the effects of the pretreatment and cold-vacuum drying methods on the physicochemical properties and antioxidant activities of dried peaches. Moisture content was significantly lower with 0.3% NaCl treatment with cold-vacuum drying. The pH, brix and acid ratio (SS/TA) were the lowest with 1.0% soluble Ca treatment, while soluble solid and SS/TA were significantly higher with 0.1% vitamin C treatment compared to those with other treatments. The ∆E and browning degree was lower in the pretreated sample compared to the untreated sample. Cutting strength of dried peaches was highest in the pretreated samples, and it was the highest with 1.0% soluble Ca treatment. Total sugar content with 0.1% vitamin C and 1.0% soluble Ca treatment was significantly higher than that with 0.3% NaCl treatment. The free sugar content was lower with 0.3% NaCl treatment but it was higher with 0.1% vitamin C and 1.0% soluble Ca treatment. The sensory evaluation result was highest with 0.1% vitamin C treatment. Phenolic compounds and antioxidant ability were the highest with the 0.1% vitamin C and 0.1% soluble Ca treatment; all the dried peaches showed relatively high antioxidant activities. These results suggest that pretreatment can affect the quality of dried peaches, showing that cold-vacuum drying can be applied for the production of high quality dried peach products.

Quality Characteristics and Antioxidant Properties in Spray-dried and Freeze-dried Powder Prepared with Powdered Seaweed Extracts

This study was designed to compare the quality characteristics of spray-dried (SD) and freeze-dried (FD) powders prepared with hot water extracts of sea mustard (Undraia pinnatifada) and sea tangle (Laminaria longissima). The moisture content of FD seawed was lower than that of SD, and sea mustard had a higher overall moisture content than sea tangle. The alginic acid content of SD seaweed was significantly higher than that of FD seaweed for both species. There were relatively higher contents of phenolic compounds in SD powders than in FD powders. DPPH radical scavenging ability was significantly greater in SD seaweed, and also, SOD-like activity in SD powders was higher than those of FD powders. However, the nitrite scavenging activity of FD powders of sea mustard (10 mg/mL) was higher than that of SD. In conclusion, spray-dried sea mustard and sea tangle extracts exhibited higher physiological functionalities than their freeze-dried counterparts.

Changes in color parameters of corn kernels during roasting

Changes in color parameters (L*, a*, b*, ΔE*, h°, and C* values) of corn during roasting were investigated and subsequently described using mathematical models. Corn kernels were roasted for 50 min at 160, 180, 200, 220, and 240°C. The L*, b*, h°, and C* values tended to decrease more rapidly as the roasting temperature and time increased up to 220°C and 50 min, whereas a* and ΔE* values tended to increase. Variation of L* and ΔE* values was found to be proportional to the roasting temperature and time. Variation of L* value during roasting above 180°C was adequately described by a first-order model. Cubic model satisfactorily described changes in all of color parameters over the temperature range. Activation energies of L* and ΔE* values were determined as 34.04 and 79.16 kJ/mol, respectively. Results suggest that L* and ΔE* values may be used as color control indicators during roasting of corn kernels.

Quality comparison of dried slices processed from whole persimmons treated with different deastringency methods

The effects of different deastringency treatments (untreated, carbon dioxide, warm water, or ethanol), before drying on the quality characteristics of dried fruit slices prepared from whole “Cheongdobansi” persimmons were evaluated. L* (lightness) and a* (redness) values of dried slices from warm water- and ethanol-treated groups were higher, respectively, compared to that of dried slices from other groups. Hardness was lower in dried slices from ethanol-treated fruits. Moisture, water activity, soluble solids, titratable acidity, and sensory properties (color, aroma, texture, sweetness, and overall acceptability) of the dried slices from astringency-removed fruits were higher when compared to those of the dried slices from non-treated persimmons. In particular, the dried slices from ethanol-treated fruits showed the highest values for these parameters. Moreover, soluble tannin and DPPH radical scavenging activity decreased by deastringency treatment. Results suggest that ethanol deastringency treatment before drying could be a useful method to improve most quality characteristics, except antioxidative activity, of dried persimmon slices.

Establishment of Mixing Ratio of Multigrain Rice for Adolescent and Aged People and Its Nutritional and Functional Estimation

This study was conducted to determine the proper mixing ratio of multigrains-added cooked rice for adolescent and aged people and analyze the nutritional and functional properties. As a result of sensory evaluation according to mixing ratio of polish rice and grains, the palatable grain mixing ratio of mixed grain rice for adolescent and aged people was 40% and 30%, respectively. The ratio of general grains to specialized grains was 9:1 in mixed grain rice for adolescent (MGA) and 8:2 in multigrain rice for aged people (MGAP). The ratio of mung bean to BacTae was 2:1 in MGA, and the ratio of adlay to buckwheat was 1:1 in MGAP. MGA contained the highest amount of crude protein, crude fat and minerals among the samples. In contrast, MGAP showed higher amounts of polyphenols and antioxidant activity compared to polished rice and MGA.

Preparation and Physicochemical Characteristics of Octenyl Succinated Rice Starches Based on Amylose Content

The purpose of this study was to investigate the preparation and physicochemical characteristics of n-octenylsuccinylated (OSAn) rice starches with different rice amylose contents. Amylose contents of Jinsumi flour and Milyang 261 flour were 15.42 and 20.31%, respectively. After processing by alkali treatment, amylose contents of Jinsumi rice starch and Milyang 261 rice starch were 34.21% and 39.32%, respectively. After OSAn treatment, the degree of substitution and reaction efficiency of Jinsumi starch were higher than those of Milyang 261. The stability of the modified Jinsumi emulsion was higher than that of the Milyang 261 emulsion. Viscosity of the Jinsumi emulsion was higher than that of the Milyang 261 emulsion. When the emulsions were spray dried, modified Jinsumi rice starch showed excellent coating efficiency compared to that of modified Milyang 261 rice starch. Therefore, Jinsumi was more suitable than Milyang 261 to apply for encapsulation as wall materials.

Physicochemical properties of aromatic rice prepared using different milling recoveries and roasting procedures

향미의 도정률에 따른 색도는 도정률이 증가할수록 L값은 증가하고 a 값 및 b 값은 감소하였으며, 갈색도 및 탁도는 감소하는 경향을 나타내었다. 총 폴리페놀, amylose 및 전분 함량은 도정률이 증가할수록 각각 28.11-33.84 ㎎/100 g, 24.97-31.06 ㎎/100 g 및 68.27-73.04%로 폴리페놀은 감소하고 아밀로오스 및 전분 함량은 증가하였다. 향미의 품질 향상을 위한 로스팅 처리는 시간이 증가할수록 L 값은 감소하고 a 값 및 b 값은 증가하였다. 총 폴리페놀 및 총 플라보노이드 함량은 로스팅 처리 구간에서 각각 37.41-41.65 ㎎/g 및 21.93-22.30 ㎎/g으로 무처리구간 33.00 ㎎/g 및 20.78 ㎎/g보다 전반적으로 증가하는 경향을 나타내었다. 아밀로오스 및 전분 함량 또한 로스팅 처리를 통해 25.06-26.10 g/100 g 및 76.38-81.81%로 무처리구에 비해 증가하였다. DPPH 및 superoxide radical 소거활성 및 FRAP에서는 로스팅 처리한 향미벼에서 61.56-67.78%, 43.14-52.90% 및 0.72-0.79 mM을 나타내어 무처리 구간보다 높은 소거활성을 나타내었다. 이상의 결과에서, 향미를 20% 도정한 다음 30분 로스팅 처리로 인해 가공적성 및 항산화 활성이 증진되어 식품가공용 소재로 다양하게 활용 가능할 것으로 사료된다.