곡류 첨가 발효유의 저장 중 HS-SPME를 이용한 휘발성 향기성분 정량분석

In this study, quantitative analysis of major volatile flavor compounds from yogurt was conducted using headspace-solid phase microextraction (HS-SPME) GC-FID analysis technique, and the changes of volatile aroma compounds during the storage period were evaluated. The yogurt was prepared with the addition of 2% cereals, such as, white rice (WR), brown rice (BR), germinated brown rice (GBR) and saccharified germinated brown rice (SGBR). After fermentation, the products were stored at $5^{\circ}C$for 15 d. The major volatile aroma compounds in yogurt, such as acetaldehyde, acetone, diacetyl and acetoin were able to be extracted using HS-SPME technique efficiently. The regression ($r^2$) value of standard curve prepared with various concentrations of individual flavor chemicals was analyzed over 0.9975, and reproducibility was acceptable to apply quantitative analysis. The analysis of volatile components of control sample during storage showed that the acetaldehyde on 0 d was 10.83 ppm, and that contents were increased to 15.67 ppm after 15 d of storage. However, addition of BR, GBR and SGBR decreased the acetaldehyde contents during storage periods. The acetone content of all treatments during storage was not significantly different. The diacetyl content of all treatments were increased during storage and the addition of SGBR showed the highest amount of diacetyl (0.84 ppm) among treatments on 15 d of storage. The acetoin content of yogurt added with grains was higher than that of control during storage. As a result, the content of volatile aroma compounds in yoghurt during storage period could be analyzed HS-SPME extraction technique effectively, and HS-SPME/GC analysis can be considered for quality control of fermented milk products. 본 연구에서는 발효유의 휘발성 향기성분을 HS-SPME/GC-FID를 이용하여 정량분석의 가능성을 검토하고, 정량 분석의 재현성 및 정확성을 확인하여 발효유의 휘발성 향기성분 연구에 접목시키고자 실험을 실시하였다. HS-SPME를 이용하여 발효유의 acetaldehyde, acetone, diacetyl 그리고 acetoin 등의 향기성분 추출 시 $35^{\circ}C$에서 가장 효과적으로 추출할 수 있었다. 그리고 발효유의 주요 휘발성 향기성분의 표준물질을 농도별로 제조하여 standard curve를 작성하여 상관관계식을 얻을 수 있었으며, $r^2$값은 모든 표준시료에서 0.9979 이상으로 뛰어난 상관관계를 나타냈다. 곡류(백미, 현미, 발아현미, 발아현미당화)를 첨가한 발효유를 제조하여 저장기간 중 휘발성 향기성분의 함량변화를 비교분석하였다. Acetaldehyde의 경우 대조구 및 백미첨가 발효유는 저장기간 중 acetaldehyde의 함량이 약 1.4배 증가하였다. 현미와 발아현미, 그리고 발아현미 당화액을 첨가한 발효유의 경우 저장 0일차 acetaldehyde의 함량이 11.78, 12.39, 12.15 ppm으로 대조구의 0일차 함량(10.83 ppm)보다 높은 함량을 나타냈지만, 저장 15일차에는 acetaldehyde 함량이 각각 11.96, 13.04, 12.10 ppm으로 대조구의 15일차 함량(15.67 ppm)보다 약 1.3배 낮은 함량을 나타냈다. Acetone은