Nutritional composition and physicochemical properties changes in mustard leaf kimchi were investigated during fermentation of up to 3 months. The pH decreased, and the titratable acidity gradually increased according to increase of fermentation periods. Fructose and glucose were the major free sugars in mustard leaf kimchi, and their amounts were significantly decreased with fermentation periods (p<0.05). Lactic acid content showed a significant increase with maximum increase at 3 months. All types of kimchi contained 20 amino acids, but the content of most amino acid fluctuated during fermentation. Except for K and Zn, the content of other ingredients including Ca, Fe, Mg, Na, Se were the highest in kimchi fermented for 2 months. The unsaturated fatty acid of mustard leaf kimchi was higher than that of saturated fatty acid, and total fatty acid of kimchi significantly decreased after 2 months (p<0.05). Most vitamin contents showed a tendency to decrease with fermentation, in particular, vitamin B complex except for B2 significantly decreased after 3 months (p<0.05). The results provide fundamental data for determining the appropriate fermentation period to improve the quality of kimchi.

Nutritional and physicochemical changes of mustard leaf kimchi were examined during fermentation periods up to 3 months. As the fermentation processed, pH decreased, and titratable acidity gradually increased. The crude ash and protein contents increased during fermentation, but crude lipid content was significantly reduced from 5.97 to 5.07%. Crude fiber and carbohydrate showed no distinct changes. Dietary fiber contents were slowly changed between control and 1 month fermentation sample, and were maintained thereafter. The major free sugars of mustard leaf kimchi were fructose and glucose, and the amount of them were significantly decreased at the end of fermentation stage. Lactic acid showed a dramatic increase and reached its maximum at 3 months. All kimchi contained 20 amino acids; in particular, glutamic acid was the highest in mustard leaf kimchi. Amino acid contents fluctuated during fermentation. Except for calcium and selenium, the content of other ingredients (Fe, K, Mg, Na, and Zn) increased with prolonged fermentation time. Fermentation promotes a significant increasing in the content of linoleic acid and DHA. The highest antioxidant vitamins (β-carotene, tocopherol) contents were determined at mustard leaf kimchi fermented for 2 months. The results will provide fundamental data for proposing an appropriate fermentation periods to promote quality of kimchi

The analytical method for the determination of phosphorus in foods was validated by inductively coupled plasma optical emission spectrometry (ICP-OES) in terms of precision, accuracy, recovery efficiency and linearity. Regression analysis revealed good correlation coefficient, higher than 0.999. Recovery efficiencies of the minerals ranged from 90.36% to 110.63%, and the limit of detection (LOD) and the limit of quantification (LOQ) were 0.0745 mg/ kg and 0.2482 mg/kg, respectively. The value of inter-day and intra-day ranged from 1.43 to 3.23% and from 0.40 to 1.77%. The recovery efficiencies ranged from 97.8 to 110.6%. The method was also compared with Molybdenum blue colorimetric method using certified and statistically significant difference was also not observed in the between two different analytical methods. The ICP-OES method was applied to phosphorus determination in commonly consumed foods. The obtained results suggest that the method verified in the present study may be used as an official analytical method for clear understanding of phosphorus database for national health promotion.

본 연구에서는 식품공전에 제시되어 있는 microwave digestion 전처리방법과 유도결합 플라즈마 방출분광기을 이용하여 식품 중의 9종의 무기질(Na, Ca, K, P, Mg, Fe, Cu, Mn 및 Zn)을 측정하는 분석법에 대한 직선성, 정밀성 및 정확성 등의 분석법 유효성 검증을 실시하였다. 본 연구에 사용된 표준시료는 Certificated reference material1849a 조제분유로 미국 national institute of standards & technology에서 구입하였다. 직선성은 표준품을 사용한 표준검정곡선 측정농도범위에서 상관계수 0.9999 이상의 양호한 결과를 나타내었다. 검출한계는 0.1005 mg/kg, 정량 한계는 0.3351 mg/kg 으로 각각 나타났다. 또한 정밀도는 상대적표준편차(relative standard deviation)가 일내(withinday, n=3), 반복측정의 경우 0.09~4.80%, 일간(between-day, n=12)의 경우 1.19~18.19%로 양호한 결과를 나타내었으며 정확성은 회수율 90.35-110.63%로 매우 양호한 결과를 나타내었다. 따라서 microwave 전처리방법과 유도결합 플라즈마 방출분광기 측정법은 식품 중 9종의 무기질을 측정하는데 매우 유용할 것으로 사료되며 국민 건강 증진을 위한 식품성분표 데이터베이스 구축, 유통식품의 품질평가 등 공익적 분석사업에 이용될 수 있을 것으로 생각된다.