Determination of furan levels in Korean agricultural products and effect of caffeic acid on the formation of furan in Maillard model systems

Abstract

Furan has been classified as a human carcinogen by the International Agency for Research on Cancer (IARC). Recently, there has been an increasing interest in the intake of furan in food. However, few studies have been reported on the analysis of furan in Korean foods and the basic research on reduction of furan. In the present study, 1) the analysis method of furan in Korean domestic agricultural products and processed foods was established. Then furan was qualitatively and quantitatively analyzed for 560 samples. In addition, 2) the effects of caffeic acid on the formation of furan and other volatile components during Maillard reaction, known as the major mechanism of furan formation, were investigated. 1) To qualitatively and quantitatively analyze furan in agricultural products and processed foods, the analytical method of furan was performed in pomegranate juice, soybean oil, and margarine matrices. The analytical method using headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) was validated by determining the linearity, limit of detection (LOD), limit of quantification (LOQ), inter- and intra-day precision (RSD %) and accuracy, and uncertainty according to ICH guidance. These results showed good efficiency of HS-SPME-GC-MS in terms linearity, LOD, LOQ, precision and accuracy in our study. As a result of analyzing the furan content of 560 agricultural products and processed foods, the detection rate of furan was 47.9% and furan was detected in the range of N.D-55.36 μg/L. 2) Formation of furan was analyzed in Maillard model systems consisting of sugar (glucose and fructose) and amino acids (serine and alanine). The content of furan was higher in a system containing fructose than glucose. Also, higher amount of furan was also produced in a system containing alanine than serine. After caffeic acid was added into Maillard model systems, the furan production was reduced by 15.5-25.6% in each Maillard model system. In the case of the Maillard model systems including furan precursors, the amounts of furan significantly was increased in the order of 1-deoxyosone, 3-deoxyosone, glyoxal, glycolaldehyde, threose, and erythrose. When caffeic acid was added into each system containing the precursors of furan, the furan in the system containing methylglyoxal, glyoxal and 1-deoxyosone was decreased by 12.3%, 12.1% and 10.4%, respectively. On the other hand, the amount of furan in the system containing threose, glycolaldehyde and 3-deoxyosone was increased by 8.0%, 7.6% and 47.2%, respectively. In the case of other volatile components in Maillard reaction, furfurals such as furfural and 5-methyl-2-furfural increased significantly, whereas pyrazines such as 2-methylpyrazine, 2,5-dimethylpyrazine, 2-ethylpyrazine, and 2-ethyl-5-methylpyrazines significantly decreased.;퓨란은 국제암연구센터(International Agency for Research on Cancer, IARC)에 의해 2급 인체 발암 가능 물질로 분류되었으며 그 위해성이 주목된 바 있는 미량 위해 물질이다. 따라서 최근 국제적으로 식품 내 퓨란의 섭취에 대한 관심이 증가되어왔으나, 국내 식품 내 퓨란의 함량 분석 및 저감화 기초 연구는 미흡한 실정이다. 본 연구에서는 국내 농산물 및 그 가공식품 내 퓨란의 분석법 확립 및 560종의 시료에 대한 정성 및 정량 분석과 퓨란의 주요 생성 메커니즘으로 알려져 있는 Maillard reaction 중 caffeic acid에 의한 퓨란 및 Maillard 반응 휘발성 산물 함량의 증감에 대해 분석하였다. 농산물 및 그 가공식품 내 퓨란을 정성 및 정량 분석하기 위해 석류주스, 콩기름, 마가린 매트릭스에서 headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) 분석법을 확립하였다. 분석법은 ICH guidance에 따라 직선성, 검출한계, 정량한계, 일간 및 일내 정밀도와 정확도 항목에서 검증되었고 분석에 대한 불확도를 측정하였다. 그 결과 모든 항목에서 좋은 결과를 보여주었다. 농산물 및 그 가공식품 560종에 대해 퓨란의 함량을 분석한 결과, 전체 시료에서 퓨란의 검출률은 47.9%이었으며 N.D-55.36 μg/L 범위로 검출되었다. 당 (glucose, fructose)과 아미노산 (serine, alanine)으로 이루어진 Maillard model system을 120℃에서 25분 가열시켜 생성된 퓨란을 분석한 결과, glucose보다는 fructose, serine보다는 alanine이 포함된 system에서 더 많은 양의 퓨란이 생성되었다. Caffeic acid 첨가 시 각 모델 시스템에서 퓨란의 생성은 15.5-25.6% 감소하여 유의미한 감소 효과를 보였다. 퓨란의 전구체가 포함된 Maillard model systems의 경우, 1-deoxyosone, 3-deoxyosone, glyoxal, glycolaldehyde, threose, 그리고 erythrose 순서로 퓨란의 함량이 유의미하게 증가하였다. Caffeic acid를 퓨란의 전구체 (methylglyoxal, glyoxal, erythrose, threose, glycolaldehyde, 1-deoxyosone, 3-deoxyosone)가 포함되어 있는 각 모델 시스템에 첨가한 결과, methylglyoxal, glyoxal, 1-deoxyosone이 들어있는 시스템에서 퓨란의 함량이 각각 12.3%, 12.1%, 10.4% 감소하였다. 반면 threose, glycolaldehyde, 3-deoxyosone가 들어있는 시스템에서 퓨란의 함량은 각각 8.0%, 7.6%, 47.2% 증가하였다. Maillard 반응 휘발성 산물을 분석한 결과, caffeic acid를 첨가할 시 furfural, 5-methyl-2-furfural과 같은 furfurals은 유의미하게 증가하였고, 2-methylpyrazine, 2,5-dimethylpyrazine, 2-ethylpyrazine, 2-ethyl-5-methylpyrazine과 같은 pyrazines은 유의미하게 감소하였다.