식품안전 총서 10 글루타민산나트륨과 안전성 -MonosodiumGlutamateandFoodSafety- 이광원 편저 (사)한국식품안전연구원 서 문 16세기 무렵 독성학이라는 학문의 기초를 세운 스위스 과학자 Paracelsus는 “모든 것에는 독이 있고, 그렇지 않은 것은 없다. 단지 적정량(right dose)이 치료약(remedy)와 독(poison)을 구분할 따름이다.”라는 현재 적용되는 위험도 평가에 기준이 유명한 주장을 하였다. 일상적인 물도 과량을 한꺼번에 섭취하면 신체에 해가 될 수 있고, 페니실린의 경우는 의사의 처방에 따라 적정량을 환자가 섭취하면 세균감염을 치료할 수 있기에, 이 경우에는 페니실린을 독으로 간주하지 는 않는다. 최대무독성량(NOEAL)값에 안전계수를 고려하여 식품첨가물의 사람 이 매일 일생동안 계속 섭취하여도 인체에 아무런 영향을 미치지 않는 양인 1일 섭취 허용량(Acceptable Daily Intake,ADI)이 설정된다. 식품의약품안전처(식 약처)는 현재의 과학적인 독성 및 안전에 관한 결과를 지속적으로 적용하여 해당 물질의 일일섭취허용량의 지속내지는 수정에 대한 검증을 하고 있다. 위해평가 결과 관련 물질의 인체섭취량이 일일섭취허용량 대비 많게 되면 규제를 받게 된다. 우리나라의 경우 식품안전에 대한 이슈가 사회적으로 큰 영향을 미치고 있다. 대표적인 식품첨가물이 L-글루타민산나트륨(L-monosodium glutamate, MSG)이다. 글루타민산나트륨은 FAO/WHO합동 식품첨가물전문가위원회에서 일일섭취허용량을 별도로 정하고 있지 않는 품목으로 분류되고 있고, 우리나라에 서도 양적 허용치가 별도로 존재하지 않을 정도로 매우 안전한 원료이다. 그렇지만 국가가 안전을 인정한 원료임에도 불구하고, 과학적이지 않은 무분별한 비난과 왜곡으로 소비자를 혼란시키고 사회․경제적으로 심각한 손실과 소모적인 논쟁 을 초래하고 있다. 이는 국내 글루타민산나트륨 생산량 및 수출량 축소로 이어져, 발효기술의 정체 및 신규 고용창출에도 악영향이 심각히 우려되고 있다. 이에 서 문 ❙ i 대해 필자는 글루타민산나트륨에 대한 올바른 정보를 정리하고 제공할 필요성을 인식하게 되었고, 불필요하고 소모적인 논쟁이 시급히 시정되기를 바라는 마음에 서 집필을 임하게 되었다. 끝으로 이 총서가 발간되기 까지 많은 도움을 주신 (사)한국식품연구원 이형주 원장님, 경규항 교수님, 오상석 교수님, 유상렬 교수님, 김해영 교수님, 하상도 교수님, 서건호 교수님, 박새롬 사무장님과 고려대학교 생명과학대학 식품공학 부 식품 생화학 및 독성학 연구실 가족들에게 깊은 감사의 뜻을 전합니다. 2014년 1월 저자 이광원 ii❙ 글루타민산나트륨과 안전성 Monosodium Glutamate and Food Safety Contents I. 글루타민산나트륨의 이화학적 특성 ···························································· 1 1. 성상 ········································································································· 1 2. 구조 ········································································································ 1 3. pH ·········································································································· 2 4. 온도 및 가열에 의한 변화 ······································································ 4 5. 용해도 ···································································································· 6 6. 글루탐산의 체내 대사작용 ····································································· 6 1) 글루탐산의 체내 대사 ····················································································· 6 2) 글루타민의 체내 대사 ····················································································· 8 3) 글루타티온의 체내 대사 ················································································ 13 7. γ-아미노낙산의 합성에 이용 ······························································· 19 8. 우마미(감칠맛) ······················································································ 21 9. 우마미(감칠맛) 상승 효과 ··································································· 22 10. 기타특성 ····························································································· 22 II. 우마미(감칠맛), 글루타민산나트륨의 맛 ················································· 24 1. 우마미(감칠맛)의 발견 ·········································································· 24 2. 식품 내 글루탐산 ·················································································· 25 3. 미각 세포와 수용체 ·············································································· 29 4. 우마미(감칠맛) 성분 ············································································· 34 5. 우마미(감칠맛) 조미료 ········································································· 38 목 차 ❙ iii III. 식품첨가물로서의 글루타민산나트륨의 이용 ········································· 42 1. 조미료의 정의 ······················································································· 42 2. 글루탐산의 조미료 역할 ······································································· 43 3. 식품첨가물로서의 글루타민산나트륨 ··················································· 47 4. 글루타민산나트륨의 저염 효과 ···························································· 52 IV. 글루타민산나트륨의 제조 ······································································· 60 1. 글루타민산나트륨 제조 공정의 역사 ···················································· 60 2. 초기 글루타민산나트륨 생산 방법 ······················································· 60 1) 추출 ················································································································ 61 2) 분리 ··············································································································· 62 3) 정제 ··············································································································· 63 3. 글루타민산나트륨 생산 방법의 발달 ···················································· 64 1) 생산 공정의 발달 ·························································································· 64 2) 새로운 원료와 부산물의 효과적인 사용 ····················································· 64 3) 화학적 합성 방법의 개발 ·············································································· 65 4) 발효 방법의 개발 ························································································ 66 4. 현재 글루타민산나트륨의 제조 공정 ···················································· 66 1) 원재료 입고 ·································································································· 67 2) 미생물발효공정 ····························································································· 68 3) 글루탐산 결정화 및 분리 ·············································································· 71 4) 글루탐산을 글루타민산나트륨으로 만들기 ·················································· 71 5) 글루타민산나트륨용액의 불순물 제거하기 ···················································· 71 6) 글루타민산나트륨 결정화 ·············································································· 72 7) 잔여 수분제거 ································································································ 72 iv❙ 글루타민산나트륨과 안전성 Monosodium Glutamate and Food Safety 8) 결정건조 및 이물검사 ··················································································· 72 9) 포장 ··············································································································· 73 5. 식품첨가물 공전 상의 글루타민산나트륨 제조 방법 ··························· 73 1) 발효법 ············································································································ 73 2) 합성법 ············································································································ 74 6. 우마미(감칠맛)을 제공하는 소재들 간의 특성 비교 ····························· 74 V. 글루타민산나트륨의 생리작용 및 신진대사 ············································· 76 1. 글루타민산나트륨의 생체 대사 및 기능 ·············································· 76 1) 소장에서의 글루타민산나트륨 대사 ······························································ 76 2) 위에서의 글루타민산나트륨 대사 ································································· 79 2. 신경전달작용과 관련된 글루타민산나트륨 ··········································· 81 1) 신경전달물질인 γ-아미노낙산(γ-aminobutyric acid, GABA)의 합성에 관여하는 글루타민산나트륨 ······························································ 81 2) 신경전달물질, 신경조절물질 그리고 관련 효소를 조절하는 글루타민산나트륨 ·························································································· 84 3) 글루타민산나트륨이 뇌손상에 부정적 영향을 미친다는 논란에 대한 과학적 안전성 검토 ······················································································ 87 3. 글루타민산나트륨에 의한 장-뇌 축 활성 및 에너지 항상성을 위한 생리적 중요성 ····················································································· 90 4. 글루타민산나트륨이 신체 에너지 대사에 미치는 영향 ························· 95 5. 글루타민산나트륨의 오해와 진실 ························································ 95 1) 중국음식증후군(Chinese Restaurant Syndrome, CRS) ····························· 95 2) 글루타민산나트륨과 임산부 및 태아 ·························································· 103 3) 글루타민산나트륨과 뇌손상 ········································································· 107 4) 글루타민산나트륨과 천식 ············································································· 113 목 차 ❙ v VI. 글루타민산나트륨의 안전성 ·································································· 122 1. 글루타민산나트륨의 독성 평가 ··························································· 122 1) 급성독성(Acute Toxicity) ············································································· 122 2) 아급성독성(Short-Term Toxicity) ······························································· 122 3) 만성독성(Long-Term Toxicity) ··································································· 123 4) 생식독성(Reproductive Toxicity) ······························································· 124 5) 유전독성(Genotoxicity) ··············································································· 125 6) 특수독성(Special Toxicity) ········································································· 125 7) 사람(Observation in Humans) ··································································· 126 2. 글루타민산나트륨의 국내 기준, 규격 ················································· 127 3. 글루타민산나트륨 국내외 분류체계 및 설정 근거 ······························ 129 1) 선진국의 분류체계 및 설정 근거 ································································ 129 2) 국내의 분류체계 및 설정 근거 ··································································· 130 4. 글루타민산나트륨 안전성 평가 결과 ··················································· 131 1) 선진국의 글루타민산나트륨 안전성 평가 결과 ············································ 131 2) 국내 식약처의 글루타민산나트륨 안전성 평가 결과 ·································· 135 5. 안전성 평가 결과 ················································································ 136 VII. 글루타민산나트륨에 대한 소비자 인식 ··············································· 140 1. 글루타민산나트륨에 대한 국내 소비자 인식 ······································· 140 2. 글루타민산나트륨에 대한 해외 소비자 인식 ······································ 149 3. 글루타민산나트륨에 대한 부정적 인식을 바꿔야 할 필요성 ··············· 152 1) 경제성 ···········································································································