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Quality Evaluation of Fresh Kimchi Cabbage in Relation to Their Kimchi Processing
Jongkee Kim 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10
Kimchi, daily food in Korea, has recently drawn a global attention as functional food in that it could prevent or treat for overcoming pandemic diseases including SARS, MERS, and COVID-19. A number of commercial varieties are available to year-round produce this leafy vegetable with high yield, disease resistance, and good quality. However, little effort has been made to bring optimum varieties to target kimchi processing. In CODEX regulation, quality standard for kimchi is consisted of acidity, saltiness, color, taste, and firmness. Especially, firmness of kimchi is largely dependent on textural characteristics of the fresh cabbage since firmness of the midrib tissue is the most important quality criterion during processing ‘kimchi’. Measuring firmness of midrib tissue using a probe, ‘Volodkevich bite jaws’ gave a consistent and highest positive correlation between firmness and the order of leaf emergence from the head of kimchi cabbage. Tissue firmness, thickness and dry mass of the midrib was compared from 16 genotypes of kimchi cabbage and their correlation was determined. Firmness of midrib tissue from outer to inner leaves became higher in all genotypes, however, their correlation between leaf order and firmness varied from 0.96 to 0.23. Mean firmness of the midrib tissue from individual head also varied from 1.58 N to 3.46 N. Thickness of leaf in individual head was positively correlated with the order of leaf emergence, being thicker in outer leaves (r²=0.86 in average from 16 genotypes). Mean thickness of midrib tissue from the head of 16 genotypes was ranged from 7.74 to 9.28 mm. Particularly, leaf thickness of “Bulam” cabbage exhibited most thinner with the least variation of midrib thickness from outer to inner leaves. Firmness and dry mass of the midrib tissue gave a positive correlation (r=0.70) from 15 genotypes. Among all the leaves in the head, the 11th leaf from the outer leaves can be served as a representative for firmness of individual head based on correlation between firmness of individual leaf and the mean firmness from every leaf in the head (r=0.81). In addition, the 10th leaf has the highest correlation in the head for total soluble solids content of the leaf. Using this simplified method, relationship between firmness of the fresh cabbage and processed kimchi was evaluated. In addition, using the simple method, inheritance of midrib firmness and total soluble solids content in kimchi cabbage was determined. These findings can be applied to breed more suitable varieties with high quality for processing kimchi.
배 과육 조직의 불용성 펙틴의 조성과 효소에 의한 가수분해
김종기(Jongkee Kim),황병호(Byung Ho Hwang),차주형(Ju Hyoung Cha),홍지흔(Ji Heun Hong) 한국원예학회 2008 원예과학기술지 Vol.26 No.3
배 주스 착즙 후 여과 및 저장 중에 생성되는 불용성 펙틴을 분해하는 효소를 분리 동정하고자 본 실험은 수행되었다. ‘신고’ 배 과육 12㎏을 시판중인 pectinase를 처리한 후 용액속의 불용성 펙틴 6.53g을 회수하였다. 이 불용성 펙틴에는 rhamnose/galacturonic acid가 0.19로 rhamnosyl기의 비율이 높았으며, 및 mannose의 함량이 40%에 달하였다. Alginate affinity 칼럼을 사용하여 시판중인 pectinase(Pectinex Ultra SP-L)로부터 polygalcturonase(PG)를 효과적으로 제거하였다. PG가 제거된 Aspergillus pectinase는 불용성 펙틴을 분해하였으며, 분해된 산물은 naringinase의 α-rhamnosidase에 의해 terminal rhamnose를 가진 올리고 당으로 확인되었다. Aspergillus pectinase 에 의해 분해된 펙틴의 분자량의 감소를 gel permeation chromatography로 확인하였으며, 올리고당의 비율은 비교적 낮았다. In order to improve juice quality and filtration process of pear (Pyrus pyrifolia) pulp extracts, insoluble pectins were obtained from pear fruit after enzymatic hydrolysis of the pulp tissue with commercial pectinases. Compositional analysis revealed that the insoluble pectin has a high ratio in rhamnose to galacturonic acid, 0.19, which was a very similar to ‘modified hairy region’ of apple pectin. In addition, the pear pectin was also rich in glucose and mannose, comprising approximately 40% of the polymer. Enzyme (s) capable to degrade the insoluble pectins was isolated from a commercial Aspergillus pecteolytic enzyme preparations using an alginate affinity chromatography. Aspergillus polygalacturonase (PG) was tightly bound to the alginate resin at pH 4.0 and efficiently separated by raising the pH of the elution buffer into 8.0. Gel permeation chromatography of the hydrolysates of insoluble pectin by the enzyme fractions unbound to the alginate resin showed a molecular weight shift from a large to a smaller weight polymers. The enzyme product, insoluble by PG, was further incubated with a α-rhamnosidase of commercial naringinase to hydrolyse terminal rhamnose. An increase in soluble, monomeric rhamnose confirmed that the fungal pectinase had an activity of hydrolyzing rhamno-galacturonosyl backbone of pectin in pear fruit. From the results obtained, it was concluded that insoluble pectins from pear fruit juice was effectively degraded by a fungal pectinase, generating oligosaccharides rich in terminal rhamnose.
초음파피로시험법을 이용한 티타튬 합금의 브레이징 접합강도 평가
안종기(Jongkee Ahn),이동엽(Dongyeop Lee),김태형(Taehyung Kim),신동익(Dongick Shin),조인식(Insik Cho),김동훈(Donghoon Kim) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.5
쉬라우드 임펠러(Shroud impeller) 제작시, 커버와 블레이드 접합을 위해 브레이징(Brazing) 공법을 활용중으로 브레이징공법은 450°C 이상에서 접합하고자 하는 모재(Base Metal)의 용융점(Melting Point) 이하에서 모재는 상하지 않고 용가재(Filler Metal)를 사용하여 열을 가하여 두 모재를 접합하는 기술을 의미한다. 일펠러로 사용되는 고온구조재료 티타늄합금에 대해 용가재는 TiCuNi 합금을 사용하였으며, 초고주기 환경에서의 피로강도를 검증하기 위해 최근 유럽과 일본을 중심으로 활발하게 연구되어지고 있는 20KHz 초음파 피로시험법을 활용하여 브레이징과 모재와의 접합피로강도 평가를 새롭게 적용하고자 하였다. 따라서 브레이징 접합 초음파피로강도시험을 위해서는 우선적으로 수십㎛의 접합층이 시험편 정중앙에 위치할 수 있도록 설계하여야 한다. 이는 초음파피로시험편은 Hourglass타입으로 최대응력진폭이 시편 정중앙에 집중되기 때문이며, 이에 맞추어 동탄성계수측정을 통한 공진시험편 설계와 정밀 가공이 이루어져야 한다. 따라서 본 논문에서는 모재부와 브레이징 접합 피로강도를 비교 평가 하고자 하였으며, 그에 따른 브레이징 공법의 신뢰성 분석 및 피로파괴 거동을 분석하고자 하였다. Shroud impeller during production, cover and into the brazing process utilizing the brazing process for bonding blade below 450℃ melting point of base metal to be joined at the base to bond two or more base by applying heat using a filler metal. Filler metal for high temperature structural materials of titanium alloy is used as a filler made of TiCuNi alloy. In order to verify the fatigue strength of the ultra-high frequency environment recently been actively studied mainly in Europe and Japan, by utilizing 20kHz ultrasonic fatigue test was to apply a new law being fatigue strength of the brazed joint and the base metal. Thus, for the brazing joint strength of the ultrasonic fatigue test should be designed to position the specimen in the center of the bonding layer. This is because the maximum stress amplitude in ultrasonic fatigue testing is in the center of the hourglass type specimen, where the dynamic elastic modulus is determined according to the resonant design and precision-machined specimens. Therefore, in this paper, the fatigue strength of base metal brazed joint was evaluated and compared. There liability analysis and fatigue fracture behavior of the brazing were analyzed accordingly.