Quality Characteristics in Mash of Takju Prepared by Using Different Nuruk during Fermentation

누룩 종류를 달리하여 담금한 탁주 발효과정중 술덧의 품질특성

The characteristics of mash qualities of takju prepared by using different nuruk (Korean-style bran koji) such as Mucor racemosus nuruk, Rhizopus japonicus nuruk, Aspergillus oryzae nuruk, Aspergillus kawachii nuruk and traditional nuruk were investigated during fermentation. At the begining of fermentation, ethanol content was in the range of $2.0{\sim}3.0%$. However, it increased to $8.2{\sim}12.6%$ after 16 days of fermentation. Takju made from Rhizopus japonicus nuruk showed higher ethanol content than treated otherwise. pH of takju made from Rhizopus japonicus nuruk showed higher value the others. Total acids were $0.15{\sim}0.20%$ at the begining of fermentation, and it increased to $0.086{\sim}1.57%$ after 16 days of fermentation. Total sugar were $16.64{\sim}17.62%$ at the begining of fermentation, but decreased to below 7.00% after 16 days of fermentation. Rhizopus japonicus nuruk showed the lowest level of total sugar content. Except ethanol, iso-amyl alcohol and iso-butyl alcohol were major part of minor alcohol in the mash of takju. Higher concentration of iso-amyl alcohol, iso-butyl alcohol and n-propyl alcohol were found in the mash of Rhizopus japonicus nuruk whereas the level of phenylethyl alcohol was high in the mash of traditional nuruk. Fusel oil was $0.002{\sim}0.411\;mg/mL$ during fermentation.

재래누룩 및 Mucor racemosus, Rhizopus japonicus, Aspergillus oryzae, Aspergillus kawachii균을 접종하여 만든 누룩으로 탁주를 담금한 후 발효과정 중의 품질을 검토한 결과는 다음과 같다. 에탄올함량은 담금직후 $2.0{\sim}3.0%$였으나 발효 16일에 $8.2%{\sim}12.6%$로 최대치를 나타냈다. Rhizopus japonicus, 재래누룩, Aspergillus kawachii, Aspergillus oryzae와 Mucor racemosus 누룩구의 술덧 순으로 높았다. pH는 담금 직후 pH $4.85{\sim}5.50$이였으나 발효 16일에는 pH $3.40{\sim}4.20$로 저하되었고 시험구 중 Rhizopus japonicus 누룩구의 술덧에서 pH가 높았다. 총산은 담금 직후 $0.15{\sim}0.20%$였으나 16일에 $0.86{\sim}1.57%$로 증가되었으며, 발효 16일에 Mucor racemosus 누룩구에서 1.57%로 시험구중 가장 높았다. 담금직후 총당의 함량은 $16.64{\sim}17.62%$, 환원당의 함량은 $4.62{\sim}5.63%$였으나, 발효 16일에 총당 $2.38{\sim}5.27%$, 환원당 $0.45{\sim}0.74%$로 감소하였고 Rhizopus japonicus구가 총당과 환원당 함량 모두 가장 낮았다. Ethanol을 제외한 알콜류 중 iso-amyl alcohol과 iso-butyl alcohol이 탁주술덧의 주성분이고, Rhizopus japonicus 누룩구에서 iso-amyl alcohol, iso-butyl alcohol, n-propyl alcohol의 함량이, Mucor racemosus 누룩구에서는 methanol의 함량이, 재래누룩구에서는 phenylethyl alcohol의 함량이 각각 높게 나타났다. 발효 중 생성된 퓨젤유는 $0.002{\sim}0.411\;mg/mL$ 이었다.