著者

熊谷 浩一 田中 尚人 佐藤 英一 岡田 早苗 Kumagai Koichi Naoto Tanaka Eiichi Satoh Sanae Okada 東京農業大学大学院農学研究科農芸化学専攻 東京農業大学応用生物科学部菌株保存室 東京農業大学応用生物科学部生物応用化学科 東京農業大学応用生物科学部生物応用化学科 Department of Agricultural Chemistry Tokyo University of Agriculture NRIC Tokyo University of Agriculture Department of Applied Biology and Chemistry Tokyo University of Agriculture Department of Applied Biology and Chemistry Tokyo University of Agriculture

出版者

東京農業大学

雑誌

東京農業大学農学集報 (ISSN:03759202)

巻号頁・発行日

vol.59, no.4, pp.274-282,

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長崎県対馬市は南北に長い島であり,対馬のそれぞれの農家ではサツマイモを原料とした固有の伝統保存食品である『せんだんご』を小規模に製造している。 せんだんごは,水で戻し,捏ねた生地を麺状に加工して茹であげ『ろくべえ麺』として食される。 ろくべえは,原料であるサツマイモ単体では生じ得ない食感を有していることから,せんだんごの製造工程に着目した。 せんだんごの製造には,"芋を腐らせる(発酵させる)"工程,それを丸めて数ヶ月に及ぶ軒下での"寒晒し"の工程があることから,島内各地域の「せんだんご製造農家」を訪問し,製造方法の調査を行った。 その結果,これら両工程にはカビなどの微生物が繁殖しており,黒色カビが繁殖した場合は味が悪くなるという理由からその部位が破棄され,白色や青色カビが繁殖した部位の製造が続行される。 このことから微生物の働きがあってせんだんごとなり,さらにろくべえ麺特有の食感が与えられると推察した。 さらに,せんだんご製造に重要な働きをすると考えられる微生物を特定するにあたり,数年にわたり島内の調査を重ねた結果,基本的にはせんだんご製造工程には3段階の発酵工程(発酵1(浸漬),発酵2(棚板に広げて発酵),発酵3(ソフトボール大の塊で発酵))と洗浄・成型工程の2工程4区分に分けられることが確認された。Sendango is an indigenous preserved food derived from sweet potato that is traditionally made in Tsushima, Japan located between the Korean Peninsula and Kyushu. The local people process a noodle called Rokube from Sendango and eat it with soup, fish or chicken. Rokube has a unique texture similar to konyaku, and unlike that of cooked sweet potato. There are two or three fermentation processes involved in Sendango production; therefore, we inferred that the unique texture of Rokube may result from the fermentation process. Sendango is manufactured in several farmhouses on the island ; however, the manufacturing process varies among districts. We investigated each local Sendango manufacturing process and determined the microorganisms involved in fermentation. The investigation of Sendango manufacturing procedures was carried out in three towns, Toyotama, Izuhara, and Mitsushima, by interviews and observations between December and February each year from 2008 to 2011. The processes consist of three main fermentations. In Fermentation-1 (F1), sliced or smashed sweet potatoes were soaked in cold water for 7-10 days. Gas production and film formation were observed during F1. In Fermentation-2 (F2), the soaked sweet potato pieces were piled to a thickness of 5-20cm for 20-30 days. Intense propagation of filamentous fungi was observed during F2. In fermentation-3 (F3), softball-sized lumps were formed on the sticky sweet potato by fungi. The sweet potatoes were left outside for approximately 1 month. The lumps gradually hardened by drying. Many fungal mycelia were observed on the surface of potatoes and inside the lumps during F3. The three aforementioned fermentation processes were used for Sendango production in two towns (Toyotama and Izuhara). In Izuhara, smashed sweet potatoes were placed in sandbags knit with plastic strings, and the bags were soaked in the flowing river water. The sandbags collected from the river water were left on the river bank for 20 days. F2 was carried out in sandbags. In Mitsushima, Sendango production consisted of two fermentation processes, F1 and F3. The fermentation process occurs over a long time period. The propagation of filamentous fungi was particularly intense during F2 and F3. It is thought that filamentous fungi are indispensable for Sendango production. We characterized the microorganisms participating in Sendango production based on this investigation.