연잎 당 침지액의 식품 성분 분석 및 미생물 변화에 대한 연구 : Studies on Food Components and Microbial Changes in Nelumbo nucifera Leaf added with Sucrose Solution

다국어 초록 (Multilingual Abstract)

Lotus (Nelumbo nucifera Gaertn) farming in Korea has a long history, and recent studies on lotus leaf have shown various beneficial effects on human health. In order to identify food components and microorganisms associated with lotus leaves fermented broth, lotus leaves were fermented in 57° Brix sugar broth over a period of 6 months. As results of analysis, the contents of crude protein, crude fat, ash, moisture, soluble sugars and amino acids indicated that the lotus contained rich sources of moisture (69.91%), crude protein (2.13%), crude fat (0.98%) and ash (2.24%). The sucrose content ratio was changed from 85.00% to 2.61%, while content ratio of glucose and fructose were changed from 5.67% to 50.24% and 9.32% to 47.15%, respectively. For the major amino acids, alanin (27.81 μg/ml), valin (13.22 μg/ml) and γ-amino-n-butyric acid (25.85 μg/ml) were analyzed in lotus leaves fermented broth. Metabolomic differences between brown sugar broth and lotus leaves fermented broth during fermentation process were investigated using gas chromatography mass spectrometry. A total 36 metabolites differed between brown sugar broth and lotus leaves fermented broth. Polyphenol and flavonoid contents were 0.7 mg/ml and 0.2 mg/ml in 180 day of lotus leaves fermented broth. For the microbial population, Kocuria kristinae and Kocuria varians were determined in brown sugar broth and Leuconostoc lactis was isolated in lotus leaves fermented broth. Based on biochemical test and 18S rDNA sequencing, Saccharomyces cerevisiae and Candida sphaerica were identified from initial stage of lotus leaves fermentation. Among them, Saccharomyces cerevisiae was a dominated microorganism at the end of fermentation.

국문 초록 (Abstract)

한국의 연 (Lotus, Nelumbo nucifera Gaertn) 재배는 오랜 역사를 가지고 있다. 연잎은 인간의 건강에 유익한 성분을 가지고 있다는 연구 보고가 있다. 이에 연잎을 이용하여 57° Brix 의 당 액을 만들고 6개월 동안 발효시키면서 발효 기간별로 식품성분분석과 미생물의 변화를 확인하였다. 분석결과, 연잎의 조단백, 조지방, 회분, 수분의 함량은 각각 수분 69.91%, 조단백 2.13%, 조지방 0.98%, 회분 2.24% 이었다. Sucrose의 함량 비율은 발효가 진행되면서 85.00%에서 2.61%로 감소하였고 glucose, fructose의 함량 비율은 각각 처음 5.67% 에서 50.24% 와 9.32%에서 47.15% 로 증가하였다. 유리 아미노산은 총 22개의 아미노산이 검출되었으며 연잎 발효액에서 대표적인 아미노산은 alanin (27.81 μg/ml), valin (13.22 μg/ml), γ-amino-n-butyric acid (25.85 μg/ml) 이었다. Polyphenol 과 flavonoid 함량은 발효 180일이 된 시점에서 각각 0.7 mg/ml 와 0.2 mg/ml 이었다. 연잎 발효액과 설탕물의 발효기간별 대사산물을 가스크로마토그래피를 이용하여 분석하였으며, 총 36개의 서로 다른 대사산물이 확인되었다. 연잎 발효액의 대표적인 일반 세균은 Leuconostoc lactis 이었고, 대조군으로 사용한 설탕물의 경우 Kocuria kristinae, Kocuria varians 가 대표적인 균이었다. 효모의 경우 생화학적 동정과 18S rDNA 유전자 분석을 이용한 결과, 연잎 발효액의 발효초기에는 Saccharomyces cerevisiae 와 Candida sphaerica 가 대표적이었으며 발효 말기에는 Saccharomyces cerevisiae 가 대표적인 효모로 나타났다.

목차 (Table of Contents)

• Contents
• Ⅰ. Introduction 1
• Ⅱ. Materials and Methods 4
• Materials 4
• Preparation of lotus leaves fermented broth 4
• Measurement of pH, color, sugar content
• and general components 5
• Analysis of free sugar content in lotus leaves
• fermented broth 6
• Analysis of free amino acids in lotus leaves
• fermented broth 7
• Determination of non-volatile organic compounds
• in lotus leaves fermented broth 7
• Determination of volatile organic compounds
• in lotus leaves fermented broth 9
• Analysis of phenolic content in lotus leaves
• fermented broth 11
• Bacteria and yeast counts 14
• Identification of bacteria in lotus leaves fermented broth 14
• Identification of yeasts in lotus leaves fermented broth 15
• Analysis of 18S rDNA of isolated yeasts 15
• Statistical analysis 16
• Ⅲ. Results and Discussion 18
• Measurement of pH, color, sugar content
• and general components 18
• Analysis of free sugar content in lotus leaves
• fermented broth 22
• Analysis of free amino acids in lotus leaves
• fermented broth 24
• Determination of non-volatile organic compounds
• in lotus leaves fermented broth 26
• Determination of volatile organic compounds
• in lotus leaves fermented broth 35
• Analysis of phenolic content in lotus leaves
• fermented broth 38
• Bacteria and yeast counts 42
• Identification of bacteria in lotus leaves fermented broth 44
• Identification of yeasts in lotus leaves fermented broth 47
• Analysis of 18S rDNA of isolated yeasts 49
• Ⅳ. Conclusion 51
• Ⅴ. References 54
• Abstract 64