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1 J Korean Soc Food Sci Nutr 한국식품영양과학회지 45(12), 1769~1775(2016) 압출성형무청분말추출물의항산화물질함량증가및이취감소 성낙윤 1 박우용 1 김이은 1 조은지 1 송하연 1 전형광 2 박재남 3 김미환 1 류기형 1 변의홍 1 1 공주대학교식품공학과 2 하늘빛 ( 주 ) 3 송원대학교식품영양학과 Increase in Anti-Oxidant Components and Reduction of Off-Flavors on Radish Leaf Extracts by Extrusion Process Nak-Yun Sung 1, Woo-Young Park 1, Yi-Eun Kim 1, Eun-Ji Cho 1, Hayeon Song 1, Hyeong-Kwang Jun 2, Jae-Nam Park 3, Mi-Hwan Kim 1, Gi-Hyung Ryu 1, and Eui-Hong Byun 1 1 Department of Food Science and Technology, Kongju National University 2 Hanbit Food 3 Department of Food and Nutrition, Songwon University ABSTRACT Aerial parts (leaves and stems) of radish are usually discarded due to the distinct undesirable flavors associated with inappropriate preparations, despite their many health benefits. In this study, we examined the role of extrusion process in the removal of off-flavors and elevation of antioxidant activity in radish (Raphanus sativus L.) leaves and stems. To optimize the extrusion conditions, we changed the barrel temperature (110, 120, and 130 C), screw speed (150, 200, 250, and 300 rpm), and moisture content (20, 25, and 30%). The polyphenol and flavonoid contents significantly increased in extruded radish leaves and stems (ER) under optimum extrusion conditions (130 C, 250 rpm, and 20%). Under extrusion conditions, we compared off-flavors (as amount of sulfur-containing compound) levels between ER and non-extruded radish leaves and stems (NER) by an electronic nose. A total of six peaks (sulfurcontaining compound) were similarly detected in both ER and NER, whereas the ER showed reduced off-flavors. Levels of glucosinolate (μg/g), which can be hydrolyzed into off-flavors during mastication or processing, were significantly decreased in the ER. From these results, extrusion processing can be an effective method to increase antioxidant activity and removal of off-flavors in radish leaves and stems. Key words: radish leaves, extrusion, off flavor, total polyphenol, total flavonoid 서 식품의품질을결정짓는다양한요인중영양성, 안전성및기호성은소비자가식품을선택하는데있어서가장중요시되는항목이다. 특히식품을섭취할때식품의맛, 색깔및향기등의기호성요인들이식품에대한소비를결정하는중요한요소로서작용한다. 따라서특정식품의지속적인수요를증가하게하려고가공및포장시발생하는이취의생성과정에대한원인을알아내고, 이를방지하거나절감할방법에대한연구들이주목받고있는추세이다 (1). 무 (Raphanus sativus) 는겨자과에속하는한해살이또는두해살이초본으로삼국시대중국으로부터도입되었으며, Received 16 August 2016; Accepted 27 September 2016 Corresponding author: Eui-Hong Byun, Department of Food Science and Technology, Kongju National University, Yesan, Chungnam 32439, Korea ehbyun80@kongju.ac.kr, Phone: 론 우리나라에서는무의뿌리및잎부분을주로식용으로사용하고있다 (2). 무의주요성분으로는수분이약 93%, 조단백질 1%, 당질 3% 및비타민 C가있으며, 그외에섬유소, 펙틴질, 각종무기질및 amylase 등이있고 methyl mercaptan 및 mustard oil 등과같은방향성분을가지고있다 (3,4). 무청은무의지상부엽채를말하며우리나라에서는건조하여국이나나물로조리하여이용하였고, 35% 이상의식이섬유및 20% 내외의단백질, 철분및칼슘등을함유하고있어과거채소가귀했던겨울철에양질의영양분을공급해온주요식품이다 (5). 그러나최근경제성장으로인해경제수준이향상되고식생활이변화함에따라재배되는무의소비량에비해서무청의소비율이적어짐에따라많은양의무청이폐기되고있다 (6). 기존의연구결과는무청추출물의항암활성, 장기능개선및간보호효과등의기능성에관한연구에국한되어왔으며 (7-9), 무청의소비율을증진하기위한제조특성에관한연구는아직미흡한실정이다.

2 1770 성낙윤 박우용 김이은 조은지 송하연 전형광 박재남 김미환 류기형 변의홍 일반적으로식물의세포벽은셀룰로오스, 헤미셀룰로오스, 펙틴및리그닌등의고분자물질로구성되어있다. 이러한식물세포벽구성성분들은상호간에이온결합, 공유결합및수소결합등을통해치밀한결합조직을이루고있어식물내부유효성분을추출하는데제한적인요소로작용한다. 따라서식물세포벽의강한결합을물리적및화학적인방법으로수용성화함으로써식물함유유효성분을다량으로용출시키기위한연구들이현재다양하게시도되고있다 (10). 압출성형은혼합, 분쇄, 가열, 성형및건조와같은연속적인단위조작을통해서전분의수화, 팽윤, 호화, 단백질의변성, 미생물의사멸, 독성물질파괴및이취물질제거반응등이연속적으로일어나는공정이며, 스크류회전속도, 수분함량및배럴온도등의공정변수조절에의해다양한특성의압출성형물을제조할수있다. 국내에서압출성형공정을이용하여식품부산물의물리적및화학적특성을개선하고자한연구들이진행되고있고, 사과주스의착즙부산물인사과박의압출성형공정에따른수용성식이섬유및펙틴의함량이증가한다고보고되었으며 (10), Ryu(11) 는두부제조시부산물인비지는압출성형공정의독립변수중수분함량의감소및스크류속도의증가에따라수용성식이섬유함량이증가한다고보고하였다. 본연구에서는부산물인무청의추출수율, 이취절감및항산화활성을향상시키기위해서압출성형의공정변수중수분함량, 스크류회전속도및배럴온도를독립변수로선택하였으며, 추출수율, 이취물질절감및항산화활성을종속변수로설정하여압출성형의조건을최적화하였다. 재료및방법재료본실험에사용된무청 (radish leaves) 은하늘빛 ( 주 ) (Gongju, Korea) 에서제공받았다. 무청의압출성형및추출압출성형무청의제조에사용된압출성형기는자체제작한실험용쌍축압출성형기 (THK 31T, Inchon Machinery Co., Incheon, Korea) 이며압출성형기의스크류직경은 29.0 mm, 직경과길이의비 (L/D ratio) 는 25:1이다. 압출성형무청의공정변수에따른최적조건을확인하기위하여수분함량조건은 20%, 25%, 30% 로설정하였고, 스크류회전속도는 150, 200, 250 및 300 rpm으로설정하였으며, 배럴온도는 110 C, 120 C, 130 C, 140 C, 150 C로달리하여압출성형물을제작하였다. 그밖의원료사입량및사출구직경은 100 g/min, 3.0 mm로고정하였다. 압출성형무청시료는실험전 50 C로유지되는열풍건조기 (HB-502MP, Han Beak Co., Bucheon, Korea) 에서 6시간동안건조하였으며, 건조된시료는가정용분쇄기 (FM-681, Hanil, Haman, Korea) 로분쇄한후 100 mesh 표준체 (Testing sieve, Chung-gye Sang-gong Co., Seoul, Korea) 를통과한분말을무청추출물의제조에이용하였다. 압출성형한무청분말 100 g에 distilled water 1 L를가해상온에서 24시간교반추출하였으며, 2,000 rpm에서 10분간원심분리하여상등액을분리하고분리된상등액을 Filter paper No. 4 (Whatman R, Kent, UK) 를사용하여감압여과한후동결건조하여무청추출물로사용하였다. 총폴리페놀함량분석압출성형한무청추출물의총폴리페놀함량은 Folin- Denis 방법 (12) 을일부수정하여분석하였다. 10 mg/ml 농도의추출물 20 μl에증류수 400 μl를가한다음, 2 N Folin-Ciocalteu phenol reagent(sigma-aldrich Co., St. Louis, MO, USA) 40 μl를넣은후교반하였다. 이용액에 20% Na 2CO μl를가한후 37 C에서 30분동안반응시킨후 microplate reader를이용하여 765 nm에서흡광도를측정하였다. 총폴리페놀정량은 gallic acid(sigma- Aldrich) 를표준물질로사용하여작성한표준곡선으로부터산출하였다. 총플라보노이드함량분석압출성형한무청추출물의총플라보노이드의함량은 Davis 방법 (13) 을일부변형하여분석하였다. 10 mg/ml 농도의추출물 500 μl에 diethylene glycol(sigma-aldrich Co.) 5 ml와 1 N NaOH 500 μl를혼합하여 37 C 항온수조에서 1시간동안반응시켰다. 흡광도의변화는 microplate reader를이용하여 420 nm에서측정하였으며, 총플라보노이드정량은 naringin(sigma-aldrich Co.) 을표준물질로사용하여작성한표준곡선으로부터산출하였다. 총글루코시놀레이트측정압출성형무청분말추출물의총글루코시놀레이트함량은 Kestwal 등 (14) 의방법을이용하여측정하였다. 추출액은동결건조된시료 1.0 g에 95% 에탄올 30 ml를넣고 100 rpm으로 24시간동안교반하여추출한후상등액을 Filter paper No. 4(Whatman R ) 로여과하여실험에사용하였다. 96 well plates에추출액 20 μl와 2 mm sodium tetrachloropalladate solution 300 μl를넣어실온에서 30분간반응시킨후 microplate reader를이용하여 450 nm에서흡광도를측정하였다. 표준물질로는 sinigrin hydrate (Sigma-Aldrich Co.) 를사용하였다. 전자코분석무청시료는강원도횡성군에서재배되는무청을공급받아 30일동안통풍이잘되는실온에서건조하였고, 실험전 60 C로유지되는열풍건조기에 4시간동안유지하면서건조하였다. 건조된시료를파쇄하여압출성형공정을수행하였고, 압출성형된무청분말과압출성형공정을거치지않은

3 압출성형무청의항산화활성및이취감소 1771 무청분말의이취를비교하기위하여전자코분석을수행하였다. 압출성형및비압출성형된무청분말 30 g씩 vial에넣은후 RTFE/silicone cap(pharma-fix, Chemea, Slovakia) 으로밀봉하였으며, 300 rpm으로교반하면서 80 C를유지하였고주입구온도는 130 C로설정하여전자코 (Smart Nose 300, SMart Nose, Marin-Epagnier, Switzerland) 분석을하였다. 각시료는 3회반복측정하였다. 이때사용된통계프로그램은 SMart Nose151 statistical analysis software(version 1.51, THOPAS Soft Creation, Marin- Epagnier, Switzerland) 이다. 통계처리이상의실험에서얻어진결과는 Statistical Package for Social Sciences(SPSS, 10.0, IBM, Chicago, IL, USA) 를이용하여 one-way ANOVA test로분석하였으며, 시료간의유의성은 Duncan s multiple range test로 P<0.05 수준에서비교하였다. 결과및고찰배럴온도에따른무청분말의수율, 총폴리페놀및총플라보노이드함량변화자연계에널리분포하는천연항산화물질은대표적으로폴리페놀및플라보노이드등이있으며, 인체내에서항균, 항암, 혈압강화작용, 피임작용, 간보호작용및진경작용등다양한생리활성기능을갖는것으로알려져있다 (15). 무청은인체유해활성산소종을소거할수있는베타카로틴및안토시아닌등다양한기능성물질을함유하고있어항산화작용에우수한생리활성을갖고있다고보고되었다 (16). 무청분말에대한압출성형공정변수중배럴온도최적조건을알아보기위하여수분함량 (25%) 및스크류속도 (250 rpm) 를고정하고배럴온도 (110 C, 120 C, 130 C, 140 C 및 150 C) 에따른추출수율, 총폴리페놀및총플라보노이드함량에관하여평가해보았다 (Table 1). 압출성형무청분말의배럴온도별추출수율은 110 C에서 40.48±1.012 %(g/g), 120 C에서 45.26±1.475%(g/g) 및 130 C에서 49.04±1.122%(g/g) 로배럴온도가증가함에따라추출수 율이증가하였으며, 특히 130 C에서는일반무청분말의추출수율 37.00±0.973%(g/g) 보다약 12% 이상추출효율이높은것으로관찰되었다. 그러나 140 C 이상의온도에서는무청분말의성형이일어나지않아 140 C 이상의높은온도에대한평가는진행할수없었다. 이전연구에서인삼의배럴온도에따른압출성형물의질소화합물과당류의추출수율이증가하는것으로보고되었다 (17,18). 본연구에서도이러한결과와유사하게배럴온도에따른무청분말압출성형물의추출수율이증가한것을확인할수있었다. 배럴온도별압출성형무청분말추출물의총폴리페놀함량은 110 C에서 21.23±1.049 mg/g, 120 C에서 25.05± mg/g 및 130 C에서 29.26±0.463 mg/g으로배럴온도가증가함에따라총폴리페놀함량이유의적으로증가하였으며, 특히 130 C에서는일반무청분말의총폴리페놀함량 (20.08±1.011 mg/g) 보다총폴리페놀함량이가장높은것으로확인되었고, 총플라보노이드함량의경우또한 110 C에서 2.38±0.067 mg/g, 120 C에서 2.52±0.021 mg/g 및 130 C에서 2.87±0.074 mg/g으로배럴온도가증가함에따라총플라보노이드함량이증가하였으며, 일반무청분말의총플라보노이드함량 (2.19±0.044 mg/g) 과비교하여 120~130 C에서유의적으로총플라보노이드함량이증가하였으나큰차이는나타나지않았다. 이전연구에서는고온에서숙성시켜제조된흑마늘의총페놀화합물이일반마늘보다높게측정되었는데, 이는숙성및가열처리로마늘조직의연화에의해높은페놀성화합물추출수율에기인한것으로보고되었다 (19). 또한, 백삼및홍삼의압출성형물추출물의총페놀화합물함량이배럴온도가증가함에따라총페놀화합물함량이높은것으로나타났다 (20). 본연구결과에서도압출성형무청분말추출물의총폴리페놀및총플라보노이드함량이배럴온도에따라증가하였으며, 이는가열처리과정중무청분말의조직연화에의한각종생리활성물질의용출이용이해진것으로생각한다. 배럴온도에따른압출성형무청분말의추출수율, 총폴리페놀및총플라보노이드함량변화에관하여관찰한결과, 배럴온도가증가함에따라압출성형무청분말의추출수율, 총폴리페놀및총플라보노이드함량이증가하는것으로확인되었으며, 추후진행하는실험에서무청분말의배럴 Table 1. Change of extraction yield, and total polyphenols and total flavonoids contents of radish leaves extracts (RLE) and extruded radish leaves extracts (ERLE) with different temperature (110, 120, and 130 o C) of extrusion condition Sample 1) Yield (g/g, %) Total polyphenols (gallic acid, mg/g) Total flavonoids (naringin, mg/g) RLE ERLE (110 C) ERLE (120 C) ERLE (130 C) 37.00±0.973 d2)3) 40.48±1.012 c 45.26±1.475 b 49.04±1.122 a 20.08±1.011 c 21.23±1.049 c 25.05±1.512 b 29.26±0.463 a 2.19±0.044 c 2.38±0.067 bc 2.52±0.021 b 2.87±0.074 a Extrusion condition: screw rotational speed 250 rpm, moisture contents 25%. 1) RLE: radish leaves extracts, ERLE (110 C): extracts from extruded radish leaves at 110 o C barrel temperature, ERLE (120 C): extracts from extruded radish leaves at 120 o C barrel temperature, ERLE (130 C): extracts from extruded radish leaves at 130 o C barrel temperature. 3) Values with different letters in same column are significantly different (P<0.05).

4 1772 성낙윤 박우용 김이은 조은지 송하연 전형광 박재남 김미환 류기형 변의홍 온도조건을 130 C로고정하여실험하였다. 스크류회전속도에따른무청분말의수율, 총폴리페놀및총플라보노이드함량변화무청분말에대한압출성형공정변수중스크류회전속도의최적조건을알아보기위하여수분함량 (25%) 및배럴온도 (130 C) 를고정하고스크류회전속도 (150, 200, 250 및 300 rpm) 에따른추출수율, 총폴리페놀및총플라보노이드함량에관하여평가해보았다 (Table 2). 압출성형무청분말의스크류회전속도별추출수율은 150 rpm에서 46.49±1.023%(g/g), 200 rpm에서 47.23± 1.112%(g/g), 250 rpm에서 48.26±1.477%(g/g) 및 300 rpm에서 48.51±1.081%(g/g) 로스크류회전속도가증가함에따라추출수율의변화는유의적인영향을미치지않았다. 스크류회전속도별압출성형무청분말추출물의총폴리페놀함량은 150 rpm에서 26.23±0.542 mg/g, 200 rpm에서 24.83±0.342 mg/g, 250 rpm에서 27.01±0.380 mg/g 및 300 rpm에서 27.32±0.588로스크류회전속도 rpm 구간에서총폴리페놀함량이증가하였으며, 총플라보노이드함량은 150 rpm에서 2.32±0.040 mg/g, 200 rpm에서 2.09±0.012 mg/g, 250 rpm에서 2.27±0.035 mg/g 및 300 rpm에서 2.18±0.029로스크류회전속도 150 및 250 rpm에서총플라보노이드함량이증가하였다. 이전연구에서스크류회전속도에따른홍삼압출성형물의진세노사이드함량의변화는스크류회전속도를 200 rpm에서 250 rpm으로증가시켰을때압출성형홍삼의총진세노사이 드함량이증가한것으로보고하였다 (18). 이로미루어보아스크류회전속도를증가시켰을때압출성형물의생리활성물질함량이증가하는것은스크류회전속도의감소에따른압출성형기내부의체류시간이증가하게되어생리활성물질의변화가있는것으로판단된다. 그러나본실험에서는스크류속도를증가시켰을때총폴리페놀의함량은증가하는경향을보였으나, 총플라보노이드의함량은유의적인차이가나타나지않는것으로관찰되었다. 수분함량에따른무청분말의수율, 총폴리페놀및총플라보노이드함량변화무청분말에대한압출성형공정변수중수분함량의최적조건을알아보기위하여배럴온도 (130 C) 및스크류회전속도 (250 rpm) 를고정하고수분함량 (20, 25 및 30%) 에따른추출수율, 총폴리페놀및총플라보노이드함량에관하여평가해보았다 (Table 3). 압출성형무청분말의수분함량별추출수율은수분함량 30% 에서 40.04±0.95%(g/g), 25% 에서 40.87±0.87%(g/g) 및 20% 에서 41.28±1.13%(g/g) 로수분함량이감소함에따라추출수율이증가하는것으로나타났다. 이전의연구에서압출성형조건중수분함량의감소및스크류회전속도의증가는홍삼압출성형물에투입되는비기계적에너지투입량이증가하여홍삼의기능성성분인산성다당체및폴리페놀의추출수율이증가한다고보고하였다 (18). 본연구에서도압출성형무청분말의수분함량에따른추출수율이증가한이유는수분함량의감소및스크류회전속도의증가에따라무청분말의수용성지수가증가하 Table 2. Change of extraction yield, and total polyphenols and total flavonoids contents of radish leaves extracts and extruded radish leaves extracts with different screw rotational speed (150, 200, 250 and 300 rpm) of extrusion condition Sample 1) Yield (g/g, %) Total polyphenols (gallic acid, mg/g) Total flavonoids (naringin, mg/g) ERLE (150 rpm) ERLE (200 rpm) ERLE (250 rpm) ERLE (300 rpm) 46.49±1.023 a2)3) 47.23±1.112 a 48.26±1.477 a 48.51±1.081 a 26.23±0.542 b 24.83±0.342 c 27.01±0.380 a 27.32±0.588 a 2.32±0.040 a 2.09±0.012 c 2.27±0.035 a 2.18±0.029 b Extrusion condition: barrel temperature 130 C, moisture contents 25%. 1) ERLE (150 rpm): extracts from extruded radish leaves at 150 rpm screw rotational speed, ERLE (200 rpm): extracts from extruded radish leaves at 200 rpm screw rotational speed, ERLE (250 rpm): extracts from extruded radish leaves at 250 rpm screw rotational speed, ERLE (300 rpm): extracts from extruded radish leaves at 300 rpm screw rotational speed. 3) Values with different letters in same column are significantly different (P<0.05). Table 3. Change of extraction yield, and total polyphenols and total flavonoids contents of radish leaves extracts and extruded radish leaves extracts with different moisture contents (20, 25 and 30%) of extrusion condition Sample 1) Yield (g/g, %) Total polyphenols (gallic acid, mg/g) Total flavonoids (naringin, mg/g) ERLE (M.C 20%) ERLE (M.C 25%) ERLE (M.C 30%) 41.28±1.13 a2)3) 40.87±0.87 a 40.04±0.95 a 29.77±0.96 a 29.66±0.80 a 29.42±0.75 a 6.91±0.25 a 6.33±0.30 b 6.67±0.48 ab Extrusion condition: barrel temperature 130 C, screw rotational speed 250 rpm. 1) ERLE (M.C 20%): extracts from extruded radish leaves at 20% moisture contents, ERLE (M.C 25%): extracts from extruded radish leaves at 25% moisture contents, ERLE (M.C 30%): extracts from extruded radish leaves at 30% moisture contents. 3) Values with different letters in same column are significantly different (P<0.05).

5 압출성형무청의항산화활성및이취감소 1773 였기때문으로생각한다. 수분함량별압출성형무청분말추출물의총폴리페놀함량은수분함량 30% 에서 29.42±0.75 mg/g, 25% 에서 29.66±0.80 mg/g 및 20% 에서 29.77± 0.96 mg/g으로수분함량이감소함에따라총폴리페놀함량이증가하였으나유의적인영향을미치지않았다. 총플라보노이드함량은수분함량 30% 에서 6.67±0.48 mg/g, 25% 에서 6.33±0.30 mg/g 및 20% 에서 6.91±0.25 mg/g으로수분함량에따른유의적차이가나타나지않았다. 이전의연구에서탈전분옥수수섬유질의페놀화합물은수분함량이 30% 에서 50% 로증가함에따라서감소하였으며, 이는원재료의수분함량에의해충분한전단력을받지못해원재료의화학적구조의단순화가이루어지지않아감소한것으로보고하였다 (21). 수분함량에따른압출성형무청분말의추출수율, 총폴리페놀및총플라보노이드함량변화에대해알아본결과수분함량의감소가압출성형무청분말의추출수율, 총폴리페놀및총플라보노이드함량에대해유의적인영향을미치지않았다. 따라서무청분말압출성형의최적조건은배럴온도 (130 C), 스크류회전속도 (250 rpm) 및수분함량 (20%) 으로결정하였다. 압출성형무청분말의총글루코시놀레이트함량글루코시놀레이트는티오글루코사이드의일종으로탄소와질소의이중결합을기준으로황과연결된 glucose와아미노산에서유래된곁사슬을갖는유기황화합물이며, 자연적으로십자과식물내에서풍부하게생성되는 2차대사산물이다 (22). 글루코시놀레이트의생합성과정에서이용되는아미노산의종류에따라서다양한곁사슬을취하며, 120 여가지에해당하는글루코시놀레이트가존재한다. 따라서글루코시놀레이트는반응기그룹의구조특성에의해크게 aliphatic, aromatic 및 heterocyclic 세그룹으로나뉘고세부적으로는 9가지로구분된다. 일반적으로글루코시놀레이트는식물세포내의액포에저장되어있고, 식물체조직이외부적요인에의해손상되면 myosin 세포의 myrosinase 효소와반응하여가수분해되어불안정한 aglycone인 thiohydroximate-o-sulfonate를형성하며, 이러한반응으로생성되는다양한가수분해물은십자과식물의주된이취성분이다 (23). 이에따라조리과정중발생하는이취를절감하기위해서가공조건에따른글루코시놀레이트의분해율및분해산물의변화에대해연구가활발히진행되고있다. 따라서압출성형공정이무청분말의글루코시놀레이트함량변화에미치는영향을평가하기위해서배럴온도 (130 C), 스크류회전속도 (250 rpm) 및수분함량 (20%) 의압출성형조건에서압출성형한무청분말및일반무청분말의총글루코시놀레이트함량에대해비교하였다 (Table 4). 일반무청및압출성형무청에서추출한총글루코시놀레이트함량을측정한결과, 압출성형무청분말추출물 4.21 ±0.10 μg/g 및일반무청분말추출물 7.21±0.14 μg/g으로 Table 4. Change of total glucosinolate contents of radish leaves extracts and extruded radish leaves extracts with optimum extrusion condition Sample 1) Total glucosinolate contents (sinigrin, μg/g) RLE ERLE 7.21±0.14 a2)3) 4.21±0.10 b Extrusion condition: barrel temperature 130 C, moisture contents 20%, 250 rpm screw rotational speed. 1) RLE: radish leaves extracts, ERLE: extracts from extruded radish leaves. 3) Values with different letters in same column are significantly different (P<0.05). 관찰되었으며, 압출성형에의해글루코시놀레이트함량이일반무청의총글루코시놀레이트함량보다약 1.5배감소하였음을확인할수있었다. 무청의총글루코시놀레이트감소에관한연구결과에서조리과정중데치기의경우식물체의손상된조직을통해글루코시놀레이트가조리수로침출되므로총글루코시놀레이트함량을감소시킨다고보고하였고 (24), 산성조건에서양성전하를나타내는키토산은전자가풍부한글루코시놀레이트와중합반응을통해무청의총글루코시놀레이트함량을낮추는것으로관찰되었다 (25). 본연구에서도이러한결과와유사하게압출성형무청분말은일반무청분말보다총글루코시놀레이트함량이낮은것으로관찰되었고, 이로미루어보아무청의가공전처리과정에서압출성형은총글루코시놀레이트함량절감에효율적인공정으로생각한다. 압출성형무청황화합물함량변화식품에서향기성분의분석은 gas chromatography(gc) 와 GC-mass spectrometry(gc-ms) 및관능검사등을통해측정되고있으나, 이와같은분석법들은시료의전처리과정및측정방법이복잡하다는단점을갖고있다 (26). 반면전자코분석은시료의전처리과정이간단하고 GC 및 GC- MS와달리구체적인성분으로동정하지않은상태에서도시료의향기성분에대한전체적인패턴을분석할수있는비교적편리한방법이다 (27). 압출성형무청분말의이취성분의함량은전자코를이용하여분석하였으며, 이취성분함량변화는 Fig. 1에나타내었다. 일반무청분말에서발생하는주요이취성분은 carbon disulfide, thiophene, 2-methylthiophene, 3-methyl-2-butene-1-thiol, dimethyl sulfoxide 및 dimethyl disulfide 등으로관찰되었으며, 배럴온도 (130 C), 스크류회전속도 (250 rpm) 및수분함량 (20%) 의조건으로압출성형된무청분말은일반무청분말보다 carbon disulfide 41.24±0.23%, thiophene 33.92±0.67%, 2-methylthiophene 20.29±1.13%, 3-methyl-2-butene-1-thiol 9.71 ±0.38%, dimethyl sulfoxide 9.71±0.59%, dimethyl disulfide 8.52±0.83% 로감소하는경향을나타냈다.

6 1774 성낙윤 박우용 김이은 조은지 송하연 전형광 박재남 김미환 류기형 변의홍 Fig. 1. Change of volatile compounds produced from RLE and ERLE in electronic nose. a: carbon disulfide, b: thiphene, c: dimethyl disulfide, d: 2-metylthiophene, e: 3-methyl-2-butene-1-thiol and dimethyl sulfoxide. 황화합물은주로음식물의부패시발생하며, 부패과정에서다양한형태의이취물질들을생성및배출하는과정에서악취를발생시킨다 (28). 악취를발생시키는물질중환원황성분들은 methyl sulfide, dimethyl sulfide, hydrogen sulfide 및 methyl mercaptan 등이대표적이며, 이들은양파, 양배추, 배추및무등과같은채소가물리적및화학적요인에의해발생하는이취성분으로잘알려져있다. 이전연구에서김치에첨가되는부재료중마늘, 생강, 양파및파에서유래하는 methyl allyl sulfide, dimethyl disulfide, diallyl disulfide, thieno[3,2-b]thiophene, 1,2,4,6-tetrathiepane 및 methyl allyl trisulfide와같은황화합물이김치에서발생하는군덕내 (staled or mold odor) 및신내 (sour odor) 등의이취를강하게생성한다고보고하였으며 (29,30), 또한고등어및명태의냉장저장과정에서발생하는 methyl mercaptan, dimethyl sulfide, carbon disulfide, dimethyl disulfide 및 dimethyl trisulfide 등과같은황화합물은그역치가낮고악취발생에크게관여하는것으로보고하였다 (31). 본연구에서압출성형된무청의이취성분에관하여전자코분석을수행한결과무청의이취성분으로 carbon disulfide, thiophene, 2-methylthiophene, 3-methyl-2-butene-1-thiol, dimethyl sulfoxide 및 dimethyl disulfide 등의황화합물이검출되었으며, 이러한황화합물의함량은압출성형공정에의해크게감소하는것으로관찰되었다. 요약무청은무의지상부엽채를말하며, 우리나라에서는주로건조하여국이나나물로조리하여이용하였고, 영양학적으로 35% 이상의식이섬유및 20% 내외의단백질, 철분및칼슘등을함유하고있다. 그러나무청의주요성분인글루코시놀레이트는가공과정중발생하는이취에주된원인물질이며, 이러한이취는무청을이용한가공식품의원료로사용하는데제한적요인이되고있다. 따라서본연구에서는압출성형조건에따른무청분말의항산화활성및이취성분변화에관하여알아보기위하여압출성형독립변수중배럴온도, 스크류회전속도및수분함량을조절하여압출성형무청추출물의추출수율, 총폴리페놀함량, 총플라보노이드함량, 총글루코시놀레이트함량및이취성분을분석하였다. 추출수율및항산화활성은배럴온도가증가함에따라유의적으로증가하였다. 압출성형최적조건인배럴온도 (130 C), 스크류회전속도 (250 rpm) 및수분함량 (20%) 에서총글루코시놀레이트함량은일반무청분말보다약 1.5배감소하는경향을나타냈으며, 이러한황화합물의함량변화에관한정확한성분을분석한결과압출성형공정은무청의이취물질 (methyl mercaptan, dimethyl sulfide, carbon disulfide, dimethyl disulfide 및 dimethyl trisulfide) 함량을효과적으로감소시켜무청의이취를감소시키는것으로관찰되었다.

7 압출성형무청의항산화활성및이취감소 1775 감사의글 본연구는중소기업청의기술혁신개발사업의일환으로수행하였음 (S , 기호성과기능성이증진된야채스프개발및산업화 ). REFERENCES 1. Hong EJ, Kim YJ, Noh BS The reduction of off-flavor in Cheonggukjang and Kimchi. Korean J Food Cult 25: Kim BR, Park JH, Kim SH, Cho KJ, Chang MJ Antihypertensive properties of dried radish leaves powder in spontaneously hypertensive rats. Korean J Nutr 43: Ku KH, Lee KA, Kim YE Physiological activity of extracts from radish (Raphanus sativus L.) leaves. J Korean Soc Food Sci Nutr 37: Jung GH, Lee HS Changes of texture in terms of the contents of cellulose, hemicellulose and pectic substances during fermentation of radish kimchi. Korean J Soc Food Sci 2: Ku KH, Lee KA, Kim YL, Lee MG Effects of pretreatment method on the surface microbes of radish (Raphanus sativus L.) leaves. J Korean Soc Food Sci Nutr 35: Lee YS, Kwon KJ, Kim MS, Sohn HY Antimicrobial, antioxidant and anticoagulation activities of Korean radish (Raphanus sativus L.) leaves. Korean J Microbiol Biotechnol 41: Rhee SJ, Ahn JM, Ku JH, Choi JH Effect of radish leaves powder on hepatic antioxidative system in rats fed high-cholesterol diet. J Korean Soc Food Sci Nutr 34: Shimotoyodome A, Meguro S, Hase T, Tokimitsu I, Sakata T Sulfated polysaccharides, but not cellulose, increase colonic mucus in rats with loperamide-induced constipation. Dig Dis Sci 46: Yim HB, Lee G, Chae HJ Cytotoxicity of ethanol extract of Raphanus sativus on a human lung cancer cell line. J Korean Soc Food Sci Nutr 33: Hwang JK, Kim CT, Hong SI, Kim CJ Solubilization of plant cell walls by extrusion. J Korean Soc Food Nutr 23: Ryu GH Treatment of Biji by extrusion-cooking and its utilization. Korean Soybean Digest 12: Appel HM, Govenor HL, D Ascenzo M, Siska E, Schultz JC Limitations of Folin assays of foliar phenolics in ecological studies. J Chem Ecol 27: Davis WB Determination of flavanones in citrus fruits. Anal Chem 19: Kestwal RM, Lin JC, Bagal-Kestwal D, Chiang BH Glucosinolates fortification of cruciferous sprouts by sulphur supplementation during cultivation to enhance anti- cancer activity. Food Chem 126: Lee SJ, Park DW, Jang HG, Kim CY, Park YS, Kim TC, Heo BG Total phenol content, electron donating ability, and tyrosinase inhibition activity of pear cut branch extract. Kor J Hort Sci Technol 24: Schmidtlein H, Herrmann K On phenolic acids of vegetables. Ⅰ. Hydroxycinnamic acids and hydroxybenzoic acids of brassica-species and leaves of other cruciferae. Z Lebensm Unters Forsch 159: Kang YH, Park YK, Oh SR, Moon KD Studies on the physiological functionality of pine needle and mugwort extracts. Korean J Food Sci Technol 27: Ha DC, Lee JW, Kim NM, Ryu GH Effect of barrel temperature and screw speed on characteristics of extruded raw ginseng. J Ginseng Res 29: Gui Y, Ryu GH The effect of extrusion conditions on the acidic polysaccharide, ginsenoside contents and antioxidant properties of extruded Korean red ginseng. J Ginseng Res 37: Jang EK, Seo JH, Lee SP Physiological activity and antioxidative effects of aged black garlic (Allium sativum L.) extract. Korean J Food Sci Technol 40: Kim BS, Ryu GH Effect of die temperature and dimension on extract characteristics of extruded white ginseng. J Korean Soc Food Sci Nutr 34: Kim CH, Ryu GH Effects of feed moisture on the physicochemical properties of extruded corn fibers. J Korean Soc Food Sci Nutr 42: Fenwick GR, Heaney RK, Mullin WJ Glucosinolates and their breakdown products in food and food plants. Crit Rev Food Sci Nutr 18: Park HU Degradation patterns of glucosinolates in cruciferous vegetables under food processing conditions. MS Thesis. Seoul National University, Seoul, Korea. p Holst B, Williamson G A critical review of the bioavailability of glucosinolates and related compounds. Nat Prod Rep 21: Jing P, Ruan SY, Dong Y, Zhang XG, Yue J, Kan JQ, Slavin M, Yu L Optimization of purification conditions of radish (Raphanus sativus L.) anthocyanin-rich extracts using chitosan. LWT-Food Sci Technol 44: Hodgins D, Simmonds D Sensory technology for flavor analysis. Cereal Foods World 40(4): Dusastre V Sniffing the world of olfaction. Nature 402: Hong OF, Kim KH The emission characteristics of reduced sulfur compounds in relation to food decay. Korean J Odor Res Eng 8: Hawer WD, Ha JH, Seog HM, Nam YJ, Shin DW Changes in the taste and flavour compounds of kimchi during fermentation. Korean J Food Sci Technol 20: Lee HY Investigation on changes of volatile components in kimchi during fermentation using targeted and non-targeted approaches. MS Thesis. Ewha Womans University, Seoul, Korea. p

Journal of Life Science 2011, Vol. 21. No μ μ

Journal of Life Science 2011 Vol. 21. No. 8. 1120~1126 ISSN : 1225-9918 DOI : http://dx.doi.org/10.5352/jls.2011.21.8.1120 μ μ μ α β Journal of Life Science 2011, Vol. 21. No. 8 1121 μ μ 1122 생명과학회지 2011,