Glucosinolate and isothiocyabate contents according to processing of Kimchi cabbage (Brassica rapa L. ssp. pekinensis)

This study examined the total glucosinolate (GSL) and isothiocyanate (ITC) contents according to different processing conditions; fresh Kimchi cabbage (Brassica rapa L. ssp. pekinensis), salted Kimchi cabbage and kimchi (storage temperature $4^{\circ}C$ and $20^{\circ}C$) using two different cultivars (Bomatnorang and Chunkwang). Four GSL peaks representing gluconapin, glucobrassicanapin, glucobrassicin and 4-methoxyglucobrassicin were detected in Kimchi cabbage by HPLC and HPLC/MS analysis. The total GSL contents of fresh Kimchi cabbage of Bomatnorang and Chunkwang were $21.37{\pm}1.06{\mu}g/g$ dry weight (DW) and $20.96{\pm}3.33{\mu}g/g$ DW, respectively. After salting, the total GSL contents of salted Kimchi cabbage decreased by 39% and 52% in Bomatnorang and Chunkwang, respectively. Finally, the total GSL contents of kimchi after storage at $20^{\circ}C$ decreased by 83% and 56% in Bomatnorang and Chunkwang, respectively. The extracted ITC contents were analyzed by GC/MS. Three ITC peaks were detected in Kimchi cabbage representing 2-phenylethyl ITC, 3-butenyl ITC and 4-pentenyl ITC. The 2-phenylethyl ITC levels increased during the salting process but this generally fell during storage at $20^{\circ}C$ as kimchi. The 3-butenyl ITC levels of Kimchi cabbage according to processing decreased rapidly due to salting and then decreased slowly during storage as kimchi. The 4-pentenyl ITC of Kimchi cabbage was lost during the salting process. The results for the change in GSL and ITC contents during the kimchi making process will be used in the food industry.

배추의 가공에 따른 glucosinolates 및 isothiocyanates 함량 변화

본 연구는 두 품종 배추(봄맛노랑 및 춘광)의 가공조건(신선배추, 절임배추, $4^{\circ}C$ 저장 김치 및 $20^{\circ}C$ 저장 김치)에 따른 GSL 및 ITC의 정성 정량 분석을 하였다. HPLC와 HPLC/MS분석 결과 봄맛노랑 및 춘광 배추에는 4종류의 GSL(sinigrin, gluconapin, glucobrassicanapin, 4-methoxyglucobrassicin)가 확인되었다. 신선배추의 총 GSL 함량은 봄맛노랑; $21.37{\pm}1.06{\mu}g/g$ DW, 춘광; $20.96{\pm}3.33{\mu}g/g$ DW에서 절임공정을 거쳐 봄맛노랑, 춘광이 각각 39%, 52% 감소하였다. 또한 김치로 가공하여 $20^{\circ}C$에 저장하였을 때 신선배추 대비 봄맛노랑, 춘광이 각각 83%, 56% 감소하여 GSL의 함량은 절임공정 및 숙성과정에서 크게 소실되는 것으로 나타났다. 또한 GC/MS분석 결과 봄맛노랑 및 춘광 배추에는 3종류의 ITC(2-phenylethyl ITC, 3-butenyl ITC, 4-pentenyl ITC)가 확인되었다. 2-Phenylethyl ITC는 봄맛노랑, 춘광에서 절임공정에 의하여 증가하였다가 $20^{\circ}C$에 저장하며 숙성되는 동안 다량 소실되었다. 3-Butenyl ITC은 절임공정에서부터 감소하는 경향을 나타냈으며, 김치로 저장하는 동안에는 크게 감소하지 않았다. 4-Pentenyl ITC는 신선배추에서만 발견되었다가 가공처리에 의해 완전히 소실되어 관찰되지 않았다. 본 연구는 향후 산업체에서 배추 가공식품의 기초자료로서 활용할 수 있을 것이다.