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1 J Korean Soc Food Sci Nutr 한국식품영양과학회지 46(10), 1225~1233(2017) 친환경세척제의처리방법을달리하여착즙한당근주스의미생물안전성및품질 임상욱 1 최다정 1 강민정 1 김종현 1 김묘정 2 김민주 1 1 ( 주 ) 휴롬바이오식품연구소 2 인제대학교바이오식품과학부 Microbial Safety and Quality of Fresh Carrot Juice Prepared with Different Environmentally-Friendly Washing Methods Sang-Wook Lim 1, Da-Jeong Choe 1, Min-Jung Kang 1, Jong-Hyun Kim 1, Myo-Jeong Kim 2, and Min-Ju Kim 1 1 Bio-Food Research Center, Hurom Co., Ltd. 2 Department of Food and Life Science, Inje University ABSTRACT The aim of this study was to evaluate the microbial inhibitory activity and physicochemical quality of fresh carrot juice prepared with different environmentally-friendly washing methods during low temperature storage. Individual and combined treatments with sodium bicarbonate (baking soda, NaHCO 3) and citric acid were applied to carrots for 10 min. and 50 ppm of sodium hypochlorite (NaOCl) were used as the control. Combined treatment of 1% NaHCO 3 and 1% citric acid significantly reduced total aerobic counts and coliforms. In addition, combined treatment of 1% NaHCO 3 and 1% citric acid inhibited microbial growth for 7 days at 4 C and 10 C in a shelf-life study. There were no significant differences among the sanitizers in terms of Brix, acidity, ph, and color. Changes in physicochemical quality were not significantly different by sanitizer but were affected by storage temperature. These results indicate that washing with combined treatment of 1% NaHCO 3 and 1% citric acid is an effective method to inhibit the microbial population and maintain physicochemical quality. Therefore, combined treatment of 1% NaHCO 3 and 1% citric acid can be effectively used to sanitize and prepare carrot juice without affecting other properties. Key words: environmentally-friendly sanitizer, sodium bicarbonate (baking soda), citric acid, combined treatment, microbial safety 서 최근건강지향및웰빙의식에대한고취로육식보다채식, 가공식품보다천연식품을선호하고있다. 이러한소비경향은음료시장에도영향을미쳐일반주스시장은정체되거나쇠퇴하는반면, 프리미엄착즙주스시장은지속해서성장하고있다 (1). 채소, 과일착즙주스에있어영양적가치는물론색, 향, 맛등의관능적특성은매우중요한요소로인식되고있어비가열살균기술에대한관심이증가하고있다. 하지만비가열살균과채주스의유통은가열살균과채주스에비해저장안전성과미생물학적위해요소에대한불안요소가크다 (2). Received 22 June 2017; Accepted 5 September 2017 Corresponding author: Min-Ju Kim, R&D Department of Bio-Food Research Center, Hurom Co., Ltd., Gimhae, Gyeongnam 50969, Korea mjkim2@hurom.com, Phone: 론 채소, 과일은재배및수확과정중병원성세균에오염될수있는확률이높고세척, 절단과정중세포의호흡속도가빨라져절단면의산화적갈변과미생물오염이일어날수있는문제점을가지고있다 (3). 따라서가공공정중중요관리점 (critical control point) 인세척공정의조건을확립하여초기세균을제어하는것은미생물학적인위해요소를억제하는데있어매우중요하다 (4). 채소, 과일의세척과정중살균소독제로가장많이이용되고있는것은차아염소산나트륨 (sodium hypochlorite, NaOCl) 용액으로, 미생물제어효과가우수하고비용이저렴하여전세계적으로가장널리사용되고있다. 하지만염소계소독액은자극적인냄새와함께유기물과의결합으로발암성물질인트리할로메탄 (trihalomethane, THM) 과클로로페놀을형성할수있어, 이에대한대안으로친환경살균소독제에대한요구도가높아지고있다 (5,6). 국내에서채소, 과일에적용하는친환경살균소독법으로는구연산등의유기산이용 (7), 탄산수소나트륨 (sodium bicarbonate, NaHCO 3)(8), 중온열처리및소성칼슘용액 (9)

2 1226 임상욱 최다정 강민정 김종현 김묘정 김민주 등이있다. 하지만이러한친환경세척방법은원료자체에존재하는미생물을저해하는데한계가있어단독세척보다병합세척시더효과적으로미생물제어를할수있다고보고되었다 (10). 본연구에서사용된탄산수소나트륨 (sodium bicarbonate, NaHCO 3) 은자연계에존재하는물질로서일명 베이킹소다 로불리며, 식품분야에서다양하게활용되고있다. Harris 등 (11) 은토마토에탄산수소나트륨을처리한결과토마토의자체오염된 Salmonella 균을 2~4 log CFU/g 감소시켰다고보고하였다. 탄산수소나트륨은물에쉽게분해되고약알칼리성을띄며높은세정력을가진것으로알려져최근가정에서도친환경세척제로자주사용되고있다 (10). 유기산은액상에서비해리된분자의형태로미생물을불활성화시켜억제하는효과가뛰어나과채류의초기미생물저해제로이용된다 (12). 특히구연산 (citric acid) 은유기산중널리사용되며시료표면의 ph를낮추어 Escherichia coli O157:H7과 S. Typhimurium의제어에탁월한것으로알려져있으며, ascorbic acid와함께과일주스에직접첨가되기도한다 (13,14). Lee(15) 는 acetic acid와 citric acid 를신선편이양배추에침지처리한결과 Pseudomonas fluorescens, E. coli 등의부패균과 E. coli O157:H7, S. Typhimurium, Staphylococcus aureus, Listeria monocytogenes 등 4종의병원성균에서 1~2 log CFU/g의생균수를감소시켰다고보고하였다. 하지만국내에서는탄산수소나트륨의식품내단독세척및탄산수소나트륨과유기산의병합세척에대한연구가아직미비한실정이다. 따라서본연구에서는착즙주스의소재로가장많이사용되지만, 자체미생물수가많아비가열살균처리를하지않으면위생학적인안전성이확보되기어려운당근에구연산, 탄산수소나트륨의병합세척조건을설정한후이조건에따라세척하고착즙한당근주스의일반미생물억제효과및품질변화를측정하고자수행되었다. 재료및방법재료및전처리본실험에사용된당근은 2016년 9월김해대형마트에서색과크기가균일한것을구입하여사용하였다. 실험전당근은흐르는물에서 1차세척하여흙과먼지를제거하고스테인리스칼로절단 ( 지름 3 cm, 길이 3 cm) 한후수돗물, 차아염소산나트륨 (NaOCl, Yuhan-Clorox, Seoul, Korea), 탄산수소나트륨 (NaHCO 3, Cheongsan Chemical Co., Ltd., Okcheon, Korea), 구연산 (citric acid, Duksan Pure Chemicals Co., Ltd., Ansan, Korea) 으로단독또는병합처리를하였다. 침지에사용된처리용액은재료대비약 10배의양을사용하였으며침지시간은 10분으로설정하였다. 단독및병합처리한당근은저속착즙기 (HH-SBF11, Hurom Co., Ltd., Gimhae, Korea) 로주스를제조하여 7일동안 4 C와 10 C에저장하면서미생물수및품질특성변화를측정하였다. 차아염소산나트륨, 탄산수소나트륨및구연산단독처리차아염소산수는 50 ppm의농도로희석한후잔류염소측정기 (Ultrapen PT4, Myron L Company, Carlsbad, CA, USA) 로염소농도를보정하여사용하였다. 탄산수소나트륨수는 1, 2, 5%(w/v) 의농도로제조하였다. 구연산수는 0.2, 0.5, 1%(w/v) 의농도로용해후사용하였다. 수돗물, 50 ppm의차아염소산수, 1, 2, 5% 의탄산수소나트륨수와 0.2, 0.5, 1%(w/v) 구연산수 2 L에각각 10분동안침지시킨 200 g의당근을수돗물로 30초간재세척한후물기를제거하고저속착즙기로주스를만들어시료로사용하였다. 탄산수소나트륨과구연산병합처리탄산수소나트륨 1% 와구연산 1% 를최적농도로결정하여네가지방법으로처리하였다 (Fig. 1). 처리구 1은당근 200 g을 1% 탄산수소나트륨과 1% 구연산을혼합한세척수 2 L에 10분동안침지후수돗물에 30초간재세척하여물기제거후저속착즙기로주스를만들어시료로사용하였다. 처리구 2는당근 200 g을 1% 탄산수소나트륨과 1% 구연산을혼합한세척수 2 L에 5분동안침지후수돗물에 30초간세척한다음다시혼합세척수 5분침지, 수돗물 30초간재세척하여물기제거후주스를만들어사용하였다. 처리구 3은당근 200 g을 1% 구연산수에 5분동안침지후수돗물에 30초간세척한다음다시 1% 탄산수소나트륨수에 5분간침지시키고수돗물로 30초간재세척하여물기제거후주스를만들어시료로사용하였다. 처리구 4는순서를바꾸어 1% 탄산수소나트륨수에 5분동안침지후수돗물 30초간세척한다음 1% 구연산수에 5분동안침지시키고재세척하는방법으로세척후주스를만들었다. 탄산수소나트륨과구연산의병합처리에따른미생물감균효과를분석하기위해무처리구와수돗물로세척한대조구, 50 ppm 차아염소산수처리구를비교분석하였다. 탄산수소나트륨과구연산병합처리후저장실험 1% 탄산수소나트륨수와 1% 구연산수로단계적병합처리한주스를멸균된폴리프로필렌튜브 (Corning, Acton, MA, USA) 에 95% 가되도록담아실험일별로개별포장하였다. 준비한시료는 4 C와 10 C에저장하면서저장 0, 1, 2, 3, 5, 7일차에세균수, 색도, 당도, ph, 산도를측정하였다. 일반세균수측정단독및병합처리한당근을착즙하여만든주스의일반세균수분석은식품공전 (16) 의방법에따라 30초동안 vortex로혼합한후주스 1 ml를취하여멸균된펩톤수 9 ml 에분주하여 10-1 에서 까지단계희석하였다. 각시료는증균과정없이직접 petrifilm aerobic count plates

3 친환경세척수병합처리가당근주스의미생물안전성에미치는영향 1227 Carrots Washing in running water and cut into 3 3 cm squares Treatment 1 Treatment 2 Treatment 3 1% NaHCO 3+1% citric acid for 5 min 1% citric acid for 5 min 1% NaHCO 3 for 5 min 1% NaHCO 3+1% citric acid for 10 min 1) Washing for 30 sec Washing for 30 sec Washing for 30 sec 1% NaHCO 3+1% citric acid for 5 min 1% NaHCO 3 for 5 min 1% citric acid for 5 min Washing for 30 sec 2) Washing for 30 sec Washing for 30 sec Washing for 30 sec Making juice Making juice Making juice Making juice Storing at 4 and 10 C Storing at 4 and 10 C Storing at 4 and 10 C Storing at 4 and 10 C Fig. 1. Flow diagram of various treatments using 1% sodium bicarbonate (NaHCO 3) and 1% citric acid for non-heat carrot juice. 1) Immersing the carrot cubes for indicated time. 2) Washing with running water for 30 sec. (Petrifilm, 3M, St. Paul, MN, USA) 에 1 ml를분주한다음 37 C에서 24~48시간배양후생성된집락수를계수하여 log colony forming units(log CFU/mL) 으로나타내었다. 대장균군수측정세척방법을달리한당근주스의대장균군분석은식품공전 (16) 의방법에따라주스 1 ml를멸균된펩톤수로 10-1 에서 까지단계희석하여측정하였다. 각시료는증균과정없이직접 petrifilm coliform count plates(petrifilm, 3M) 에 1 ml를분주한다음 37 C에서 24~48시간배양후생성된집락수를계수하여 log CFU/mL로나타내었다. 당도, ph 및산도측정당근주스의저장기간중당도, ph, 산도의변화를측정하였다. 주스의당도는주스 1 ml를취한후당도계 (Pal-1, Atago Co., Ltd., Tokyo, Japan) 를사용하여 24~25 C에서 3회반복하여측정한후 Brix로나타내었다. 주스와세척수의 ph는 ph meter(ag8603, Mettler Toledo, Zurich, Switzerland) 를사용하여 3회반복측정하였다. 산도측정은주스를 4,000 rpm에서 10분간원심분리하여상층액 50 ml를취한후 0.1 N NaOH 용액으로 ph 8.3이될때까지적정하고아래의계산식을이용하여구연산으로서총산함량 (%) 을구하였다. [{0.1 N NaOH 적정량 (ml) 0.1 N NaOH 산도 (%)= 역가 희석배수 }/ 시료채취량 (g)] 100 색도측정당근주스의색도는주스 5 ml를취하여색차계 (CR- 200, Minolta, Osaka, Japan) 로 Hunter s value인 L, a, b값을 3회반복측정하여평균치를구하였다. 이때사용한표준백판의 L, a, b값은각각 L=96.75, a=-0.19, b=20이었다. 통계처리통계분석은 SPSS 통계프로그램 (Statistical Package for the Social Science, Ver. 24.0, SPSS Inc., Chicago, IL, USA) 을이용하여각처리군의평균과표준편차를산출하였고, 처리구간의차이는 one-way ANOVA(analysis of variation) 로분석한후 Duncan s multiple range test를이용하여 P<0.05 수준에서유의성을검증하였다. 결과및고찰차아염소산나트륨, 탄산수소나트륨과구연산의단독처리에따른세균수변화당근에농도별로제조한차아염소산수, 탄산수소나트륨수와구연산수를단독처리한후착즙한당근주스의일반세균수와대장균군변화를 Table 1에나타냈다. 수돗물침지세척후착즙한당근주스의일반세균수는 4.90 log CFU/mL로세척하지않은당근초기일반세균수 (5.07 log CFU/mL) 에비해 0.17 log CFU/ ml 감소되었다. Lee 등 (17) 은오미자를수돗물로세척하여총균수를 0.28 log CFU/mL 감소시켜수돗물단독세척만으로는세균수감소효과가낮다고보고하였으며, 본연구에서도수돗물단독

4 1228 임상욱 최다정 강민정 김종현 김묘정 김민주 Table 1. Change in the populations of total aerobic bacteria and coliforms following treatments with tap water, sodium hypochlorite (NaOCl), sodium bicarbonate (NaHCO 3) and citric acid Treatment Control 1) NaHCO 3 1% 2% 5% Citric acid 0.2% 0.5% 1% ph ± ± ± ± ± ± ±0.01 Total aerobic bacteria (log CFU/mL) 5.07±0.01 i2) 4.90±0.02 h 4.27±0.01 c 4.69±0.02 e 4.77±0.02 f 4.81±0.02 g 4.56±0.03 d 4.04±0.03 b 3.89±0.02 a 1) Control: no treatment. 2) Means with different superscripts (a-i) in the same column are significantly different at P<0.05. Coliforms (log CFU/mL) 3.97±0.02 i 3.91±0.02 h 2.63±0.02 b 3.85±0.02 f 3.80±0.03 e 3.63±0.02 d 3.86±0.02 g 2.81±0.02 c 2.50±0.04 a 세척만으로당근의위생적안전성을보장할수없음을확인하였다. 이에최근그사용이증가하고있는친환경세척제를이용하여미생물제어정도를조사하였으며, 친환경세척제의살균정도를비교하기위하여일반적으로과채류세척제로많이사용되는차아염소산수를이용하였다. 본연구에서 50 ppm 차아염소산수에 10분간침지시킨당근으로착즙한주스의경우당근대조구에비해일반세균수가 0.8 log CFU/mL 감소하였으며처리농도에비례하여일반세균수감소효과가나타났다. Ding 등 (18) 이 100 ppm의차아염소산수를버섯에처리한결과일반세균수 1.14 log CFU/ ml 를감소시킨다고보고한것과유사한결과로염소수세척이미생물제어에효과적임을알수있었다. 그러나차아염소산나트륨은건강에유해한유기물의생성과채소, 과일세척후염소특유의냄새로인한문제점을나타내는것으로보고되고있어본연구에서는탄산수소나트륨및구연산처리가미생물감소에미치는영향을조사하였다 (5). 당근에탄산수소나트륨수를 1, 2, 5% 농도로각각처리하여착즙한당근주스의일반세균수를분석한결과 4.69~ 4.81 log CFU/mL로나타났으며, 예상과달리미생물제어효과가탄산수소나트륨농도에비례하지는않는것으로나타났다. 1% 탄산수소나트륨에서가장우수한미생물제어효과를나타내어대조구에비하여 0.38 log CFU/mL 감소시켰으며, 이는 50 ppm 차아염소산수의미생물제거율에는미치지못하는수준이었다. 탄산수소나트륨은항균성이우수하여특히구강및치과관련제품의살균제로많이이용되고있으며, 호기성균제어에더효과적으로작용한다 (19, 20). 최근친환경세척방법에대한관심이증가하면서채소, 과일등식재료세척시맛과식감유지및 ph 조절등과같은장점을나타내는탄산수소나트륨을많이사용하고있으나식품을세척할경우탄산수소나트륨의농도는 2% 이상사용하지않는다고보고되었다 (8). 구연산수처리에따른일반세균수는 0.2, 0.5, 1% 농도에서각각대조구와비교하여일반세균수를 0.51, 1.03, 1.18 log CFU/mL 감소시켜, 구연산농도가증가할수록미생물 감균효과가우수한것으로나타났다. 또한, Rahman 등 (21) 이 1% 구연산수로처리한시금치에서일반세균수를 1.39 log CFU/mL 감소시켰다고보고한것과유사한결과를나타냈다. 유기산은해리되지않은산분자의이온화에의해미생물세포내 ph를감소시켜미생물생육을저해하는것으로보고되었으며 (12,14), 본연구결과에서도 1% 구연산수의감균효과가가장낮은것으로나타나이러한사실을뒷받침해주었다. 1% 구연산수로처리한당근주스의대장균군은 2.50 log CFU/mL로대조구에비해 1.47 log CFU/mL를감소시켜효과적으로대장균군을감소시키는것으로나타났다. Chang 등 (22) 도메밀새싹에아세트산, 아스코르브산, 구연산등의유기산중 0.5% 구연산으로단독처리했을때대장균군을 6.77 log CFU/mL에서 5.89 log CFU/mL로감소시켰다고보고하여대장균군제어에있어구연산이매우효과적임을확인할수있었다. 본연구에서는구연산을 0.2, 0.5, 1% 농도로처리한결과 1% 구연산을처리한경우대장균군제어효과가가장우수하였다. 따라서 1% 구연산수단독세척만으로도 50 ppm의차아염소산수로세척하는것에비해효과적으로당근의초기미생물수를제어할수있음을확인하였다. 탄산수소나트륨과구연산의혼합및단계적병합처리에따른세균수변화당근에친환경세척수를단독처리한결과우수한미생물감균효과를나타낸 1% 탄산수소나트륨수와 1% 구연산수를병합처리한후착즙한당근주스의미생물수변화를 Table 2에나타냈다. 1% 탄산수소나트륨수와 1% 구연산수를혼합하여 10분간침지시켜세척한처리구 1 당근주스의일반세균수와대장균군은각각 4.82 log CFU/mL와 3.79 log CFU/mL로나타나미생물제거효과를나타내지못했다. 1% 탄산수소나트륨수와 1% 구연산수를혼합하여 5분간침지시킨후세척하여다시 5분간침지후세척한처리구 2 당근주스의일반

5 친환경세척수병합처리가당근주스의미생물안전성에미치는영향 1229 Table 2. Effects of combined treatment of NaHCO 3 and citric acid on total aerobic bacteria and coliforms Control 1) Treatment 1 Treatment 2 Treatment 3 Treatment 1% NaHCO 3+1% citric acid (10 min) 1% NaHCO 3+1% citric acid (5 min 5 min) 1% citric acid 1% NaHCO 3 (5 min 5 min) 1% NaHCO 3 1% citric acid (5 min 5 min) Total aerobic bacteria (log CFU/mL) 5.07±0.01 f2) 4.90±0.02 e 4.27±0.01 c 4.82±0.02 d 4.81±0.02 d 3.35±0.01 b 3.20±0.01 a 1) Control: No treatment. 2) Means with different superscripts (a-f) in the same column are significantly different at P<0.05. Coliforms (log CFU/mL) 3.97±0.02 e 3.91±0.02 d 2.63±0.02 b 3.79±0.01 c 3.80±0.01 c 2.63±0.02 b 2.41±0.01 a 세균수는 4.81 log CFU/mL로침지시간이나세척횟수와관계없이처리구 1과유사한결과를보였다. 살균방법중병합처리를하는 hurdle technology에있어서 ph의조절은살균효과를높이는데매우중요한요소이다 (14). 본연구에사용된구연산과탄산수소나트륨은각각약산성과약알칼리성으로, 이를혼합하여사용할경우세척용액은중성으로변하면서살균효과가감소한것으로판단된다 (23). 따라서탄산수소나트륨수와구연산수의병합처리에있어세척제침지시간이나세척횟수보다세척제의 ph가미생물감균효과에미치는영향이더크다는것을확인할수있었다. 1% 구연산수침지후 1% 탄산수소나트륨수로단계적병합처리한처리구 3 당근주스는처리구 1보다일반세균수 1.47 log CFU/mL, 대장균군 1.16 log CFU/mL를감소시켰다. 이는구연산수로 1차살균후탄산수소나트륨으로 2차살균되는단계적처리로미생물이제거되기때문으로생각된다. 이러한결과를바탕으로탄산수소나트륨과구연산의단계적처리방법이혼합하여처리하는세척법보다일반세균수와대장균군의제어에더효과적임을알수있었다. 두세척수의순서를바꾸어 1% 탄산수소나트륨수처리후 1% 구연산수순서로단계세척처리한처리구 4의미생물감균효과를조사한결과, 처리구 1보다일반세균수 1.62 log CFU/mL를감소시켰다. 대장균군은처리구 1보다 1.38 log CFU/mL 감소시켰으며, 50 ppm 차아염소산수와처리구 3에비해서도 0.22 log CFU/mL 감소하여가장높은미생물제어효과가있음을확인하였다. 이는먼저탄산수소나트륨수처리시약알칼리가계면활성제로서역할을하여조직내구연산의침투효과를증대시켜침투된구연산은세포내 ph 감소및효소를불활성화시켜미생물의생육을저해하기때문으로판단된다 (24). 이러한결과를바탕으로 1% 탄산수소나트륨수처리후 1% 구연산수의단계적병합처리방법이두용액을혼합하여처리하거나 1% 구연산수처리후 1% 탄산수소나트륨수순서로처리하는것에비해미생물제어효과가우수한것으로판단된다. 탄산수소나트륨과구연산의단계적병합처리에따른저장온도별세균수변화탄산수소나트륨수와구연산수의단계적병합처리에따 른저장온도별미생물변화를측정하기위해당근주스를 4 C 및 10 C에저장후세균수의변화를 Fig. 2에나타냈다. 식품위생법의식품및식품첨가물의설정기준에따르면비가열과채주스류의유통기간은 0~10 C에저장하여 3일이며, 식품공전의 식품일반에대한공통기준및규격 에서비가열과채주스류의일반세균수는 1 ml당 5.0 log CFU/ ml 이하로규제하고있다 (25). 이를기준으로보면당근은일반세균수 5.07 log CFU/mL로기준치를초과하여비가열과채주스제조에있어주의를기울여야하는재료이다. 수돗물처리구, 차아염소산수처리구, 단계적병합처리구의일반세균수는 7일동안서서히증가하였다. 4 C에저장한수돗물처리구는저장 1일후, 50 ppm 차아염소산수처리구 A Total aerobic bacteria. (log CFU/mL). B Total aerobic bacteria. (log CFU/mL) Fig. 2. Change in the populations of total aerobic bacteria in carrot juice during storage at (A) 4 C and (B) 10 C. ( ) Tap water, ( ), ( ) 1% NaHCO 3 1% citric acid.

6 1230 임상욱 최다정 강민정 김종현 김묘정 김민주 는저장 5일후식품기준규격을초과하였으나탄산수소나트륨수와구연산수의단계적병합처리구는 7일후 4.55 log CFU/mL를유지하여일반세균수기준치를충족시켜미생물증식저해효과를유지하는것으로나타났다. 각각의세척수로처리한당근주스를 10 C에저장한경우저장 1일째부터미생물수가급격하게증가하기시작하였으며, 수돗물처리구와 50 ppm의차아염소산수는저장 1일후, 1% 탄산수소나트륨수와 1% 구연산수의단계적병합처리구는저장 3일후부터일반세균수 5.0 log CFU/mL 기준을초과하여 1% 탄산수소나트륨수와 1% 구연산수의단계적병합처리가저장기간에미생물증식억제효과가가장우수한것으로나타났다. 4 C와 10 C에서저장한수돗물처리구, 50 ppm 차아염소산수처리구와단계적병합처리구의모든일반세균수는저장 5일후최대에도달했다가 7일째부터감소하는경향을보였는데이는균증식으로인한산의생성으로증식된균이사멸되었기때문으로생각된다 (26). 1% 탄산수소나트륨수와 1% 구연산수의단계적병합처리구를 4 C 저장시 7일간일반세균수가 1.35 log CFU/mL 증가했지만 10 C 저장시 3.05 log CFU/mL로급증하여저장온도가미생물증식에있어중요한요소임을확인할수있었다. Sun 등 (27) 의연구에서도신선편이당근을 4 C에서저장시미생물성장이저지되는반면에 10 C에서는유의적으로증가한다고보고하여본연구결과와일치하였으며, Kubheka 등 (28) 은많은식중독균의생육온도가 5~46 C로온도를 4 C 이하로유지해야만미생물증식억제및채소류의품질을유지할수있다고보고하였다. 대장균군의경우에도일반세균수와유사한경향을보였으며당근에 1% 탄산수소나트륨수와 1% 구연산수를단계적병합처리하여 4 C 저장시대장균군은 7일간 1.05 log CFU/mL 증가했지만 10 C 저장시 2.72 log CFU/mL 증가하였다 (Fig. 3). 본연구결과 1% 탄산수소나트륨수와 1% 구연산수의단계적병합처리는당근의초기미생물제어가저장기간에도영향을미쳐미생물증식억제에도움이되는우수한살균처리방법으로생각된다. 또한, 비가열과채주스의저장에있어서온도는미생물안전성에중요한요소로서, 특히당근주스와같이초기세균수가많은과채주스의경우 4 C 이하로보관해야만미생물학적안전성을확보할수있다는것을확인하였다. 탄산수소나트륨수와구연산수의단계적병합처리에따른당근주스저장중품질변화 1% 탄산수소나트륨수와 1% 구연산수의단계적병합처리후착즙한당근주스를 7일동안저장온도를달리하여당도, 산도, ph, 색도변화를조사하였다 (Table 3). 탄산수소나트륨수와구연산수를단계적병합처리한당근주스를 4 C 저장하여 7일동안관찰한결과당도는 7.87 Brix, 산도는 0.11%, ph는 6.34로나타났으며저장기간 A Coliforms (log CFU/mL). B Coliforms (log CFU/mL) Fig. 3. Change in the populations of coliforms in carrot juice during storage at (A) 4 C and (B) 10 C. ( ), ( ), ( ) 1% NaHCO 3 1% citric acid. 및처리구에따른유의적인변화는없었다. 각각의세척수로처리하여 10 C 저장시수돗물처리구, 50 ppm 차아염소산처리구, 1% 탄산수소나트륨수와 1% 구연산수의단계적병합처리구의당도는모든군에서 7.83 ~7.87 Brix에서 7.03~7.13 Brix로유의적으로감소하였으나처리구간의차이는없었다. 이는사탕수수착즙액에서온도가높아질수록효소에의한당의가수분해가증가한다는연구와일치하는결과로당도에서도온도는중요한요소임을알수있었다 (29). 세척수처리에따른당근주스의산도는모든군에서 10 C 저장 5일부터유의적으로증가하여 ph가감소하였으며, 이는저장중젖산균에의한유기산생성으로부터기인한것으로생각된다 (26,30). 당근주스의산도와 ph 또한저장기간에따른차이는있으나처리방법에따른차이는크게나타나지않았다. 따라서채소, 과일의품질유지에있어서세척수의처리방법보다저장온도가더중요한요소임을확인할수있었다. 당근에 1% 탄산수소나트륨수와 1% 구연산수의단계적병합처리후착즙한주스시료의저장중품질유지여부를확인하기위해저장온도별색도를측정하였다 (Table 4). 색도항목중 Hunter L은색의밝기, a는적색도, b는황색도를나타낸다 (31). 색도를측정한결과당근주스의 Hunter b값은처리방법과저장온도에따른유의적차이가나타나지않았다. 하지만 Hunter L과 a값은 4 C와 10 C에서모두증가

7 친환경세척수병합처리가당근주스의미생물안전성에미치는영향 1231 Table 3. Change in the quality characteristics of carrot juice during storage at 4 C and 10 C Quality characteristics 4 C 10 C Total sugar ( Brix) Acidity (%) ph Total sugar ( Brix) Acidity (%) ph Treatment 1) nsns2) 7.87±0.06 NS NS NS3) 0.13±0.01 bns NS 6.35±0.01 nsns 6.35±0.01 NS 6.35±0.01 NS nsd4) 7.87±0.06 C C AB 0.13±0.01 ba A 6.35±0.01 nsd 6.35±0.01 D 6.35±0.01 D ns 0.14±0.01 b 0.10±0.01 a 6.35±0.01 ns 6.35± ± ±0.01 nsd 7.87±0.06 C 7.87±0.06 C 0.13±0.01 abb 0.14±0.01 ba A 6.35±0.01 nsd 6.34±0.01 D 6.34±0.01 D 7.80±0.01 ns 0.10±0.01 a 0.14±0.01 b 6.34±0.02 ns 6.35± ± ±0.06 nsd C 7.87±0.06 C 0.11±0.01 nsab 0.13±0.01 A 0.13±0.02 A 6.24±0.01 nsc 6.23±0.02 C 6.23±0.02 C 7.87±0.06 ns 7.77± ±0.01 a 0.13±0.01 c 0.12±0.01 b 6.35±0.01 ns 6.33± ± ±0.10 nsc 7.40±0.10 B 7.50±0.01 B 0.10±0.01 aa 0.13±0.01 ba ba 6.22±0.02 nsc 6.22±0.02 C 6.22±0.01 C ns 7.87± ± ±0.01 b 6.36±0.01 ns 6.35± ± ±0.01 nsb 7.30±0.10 B 7.40±0.10 B 0.33±0.01 ac 0.41±0.01 bb 0.34±0.01 ab 5.74±0.01 nsb 5.74±0.01 B 5.75±0.01 B 7.87±0.06 ns 7.87± ± ±0.01 a 0.14±0.01 b 6.34±0.02 ns 6.35± ± ±0.10 nsa 7.03±0.06 A 7.13±0.12 A 0.54±0.01 ad 0.62±0.01 bb 0.55±0.01 ac 4.31±0.01 nsa 4.32±0.02 A 4.32±0.02 A 1) Treatment 1% citric acid after 1% NaHCO 3. 2) ns, NS: Not significant. 3) Means with different superscripts (a-c) in the same column are significantly different from physicochemical quality and washing treatments at P< ) Means with different superscripts (A-D) in the same row are significantly different from physicochemical quality and storage time at P<0.05. Table 4. Change in Hunter L, a, b value of carrot juice during storage at 4 C and 10 C Hunter s color 4 C 10 C L * a * b * L * a * Treatment 1) 46.48±0.09 nsns2) 46.47±0.05 A 46.43±0.08 A 13.51±0.05 nsa 13.48±0.04 A 13.48±0.02 A 18.16±0.04 nsns 18.15±0.01 NS 18.17±0.03 NS 46.48±0.09 nsa4) 46.47±0.05 A 46.43±0.08 A 13.51±0.05 nsa 13.48±0.04 A 13.48±0.02 A 46.50±0.03 ns 46.50±0.03 A 46.48±0.05 AB 13.50±0.03 nsa 13.49±0.05 A 13.49±0.03 A 18.12±0.01 ns 18.16± ± ±0.05 nsa 46.49±0.03 A 46.49±0.06 A 13.47±0.05 nsa 13.50±0.01 A 13.47±0.02 A 46.50±0.03 ns 46.51±0.03 A 46.50±0.06 AB 13.46±0.06 nsa 13.46±0.04 A 13.45±0.04 A 18.14±0.01 a3) 18.16±0.02 b 18.16±0.02 b 46.47±0.09 nsa 46.48±0.07 A 46.47±0.05 A 13.45±0.03 aa 13.43±0.01 aa 13.48±0.02 ba 46.50±0.04 ns 46.50±0.04 A 46.51±0.03 AB 13.50±0.06 nsa 13.47±0.04 A 13.46±0.04 A 18.15±0.05 ns 18.15± ± ±0.06 nsb 46.78±0.03 B 46.80±0.03 B 13.74±0.03 nsb 13.74±0.04 B 13.76±0.04 B 46.62±0.03 ns 46.61±0.09 A 46.61±0.03 B 13.66±0.04 nsb 13.65±0.04 B 13.65±0.02 B 18.16±0.02 ns 18.18± ± ±0.03 nsc 47.17±0.04 C 47.20±0.03 C 14.56±0.03 nsc 14.56±0.02 C 14.56±0.04 C 46.78±0.01 ns 46.77±0.05 B 46.79±0.03 C 13.85±0.04 nsc 13.85±0.03 C 13.86±0.04 C 18.15±0.03 ns 18.15± ± ±0.03 nsd 48.20±0.04 D 48.19±0.05 D 15.65±0.04 nsd 15.66±0.04 D 15.66±0.03 D b * 18.16±0.04 nsns 18.15±0.01 NS 18.17±0.03 NS 18.17±0.02 ns 18.14± ± ±0.03 ns 18.13± ± ±0.03 ns 18.19± ± ±0.02 ns 18.17± ± ±0.02 ns 18.16± ±0.02 1) Treatment 1% citric acid after 1% NaHCO 3. 2) ns, NS: Not significant. 3) Means with different superscripts (a,b) in the same column are significantly different from physicochemical quality and storage time at P< ) Means with different superscripts (A-D) in the same row are significantly different from physicochemical quality and washing treatments at P<0.05.

8 1232 임상욱 최다정 강민정 김종현 김묘정 김민주 하는경향을나타냈다. 당근주스를 10 C 저장시모든처리구의 L값은 46.43~46.48에서저장 7일후 48.19~48.21로증가하였으며, 저장 3일부터유의적으로증가하여저장기간이증가함에따라수분의감소와리그닌화로인한백화현상이진행되어명도가증가한다는보고와일치하였다 (32). 처리방법을달리한당근주스를 10 C에서 7일동안저장시 a값은 13.48~13.51에서 15.65~15.66으로유의적으로증가하였으나처리방법에따른유의적차이는나타나지않았다. 따라서본연구에서사용된 1% 탄산수소나트륨과 1% 구연산수의단계적병합처리는당근주스의색도품질에영향을미치지않았고저장중품질유지에있어서도우수한방법으로생각된다. 또한, 채소과일의품질유지에있어서는세척처리방법보다저장온도에의한영향을더많이받는것으로조사되었으며, 저장시 4 C 이하로유지하는것이매우중요하다는것을확인할수있었다. 요약본연구에서는당근의세척에사용되는친환경세척제의초기미생물제어효과를향상시키기위해탄산수소나트륨과구연산의단독및병합처리조건을설정하였으며저장중당근주스의미생물수및품질특성변화를분석하였다. 친환경세척제의단독처리방법으로는 0.5, 1, 2% 탄산나트륨수와 0.2, 0.5, 1% 구연산수를적용하였고, 살균효과를비교하기위해무처리구, 수돗물처리구, 50 ppm 차아염소산나트륨처리구를사용하였다. 당근의세척을위한병합처리방법으로는단독처리에서우수한살균효과를나타낸 1% 탄산수소나트륨수와 1% 구연산수를이용하였고, 1% 탄산수소나트륨수처리후 1% 구연산수로처리하는단계적병합처리구가가장우수한살균효과를나타내었다. 1% 탄산수소나트륨수와 1% 구연산수의단계적병합처리구는무처리구에비해일반세균수 1.87 log CFU/mL, 대장균군 1.56 log CFU/mL를감소시켰고, 50 ppm 차아염소산수에비해서도일반세균수 1.07 log CFU/mL, 대장균군 0.22 log CFU/mL의미생물감균효과를나타냈다. 1% 탄산수소나트륨수처리후 1% 구연산수의단계적병합처리구를 4 C에서 7일동안저장한결과수돗물, 50 ppm 차아염소산수나혼합병합처리구, 1% 구연산수처리후 1% 탄산수소나트륨처리구에비해미생물제어효과가확실하게나타났지만, ph, 당도, 산도, 색도에는유의적인차이가나타나지않았다. 본연구결과 1% 탄산수소나트륨과 1% 구연산의단계적병합처리는당근세척시초기미생물제어와품질유지에있어효과적인살균처리방법으로비가열당근주스의유통기간동안미생물안전기준에부합하며주스의품질을유지할수있는바람직한세척방법으로판단된다. REFERENCES 1. Chung HJ Comparison of physicochemical properties and physiological activities of commercial fruit juices. Korean J Food Preserv 19: Kwon SC Microbiological evaluation for HACCP system application of green vegetable juice containing lactic acid bacteria. J Korea Acad Industr Coop Soc 12: Wiley RC Minimally processed refrigerated fruits and vegetables. Chapman & Hall, Inc., New York, NY, USA. p Kim JW, Kim SH Establishment of washing conditions for salad to reduce the microbial hazard. Korean J Food Cook Sci 21: Park SS, Sung JM, Jeong JW, Park KJ, Lim JH Efficacy of electrolyzed water and aqueous chlorine dioxide for reducing pathogenic microorganism on Chinese cabbage. Korean J Food Sci Technol 44: Kraybill HF Origin, classification and distribution of chemicals in drinking water with an assessment of their carcinogenic potential. In Water Chlorination. Jolly RL, ed. Ann Arbor Science, Ann Arbor, MI, USA. Vol 1, p Jin Y, Kim TW, Ding T, Oh DH Effect of electrolyzed water and citric acid on quality enhancement and microbial inhibition in head lettuce. Korean J Food Sci Technol 41: Corral LG, Post LS, Montville TJ Antimicrobial activity of sodium bicarbonate. J Food Sci 53: Kim JG, Nimitkeatkai H, Choi JW, Lee SG The effects of calcinated calcium solution washing and heat treatment on the storage quality and microbial growth of freshcut broccoli. J Bio-Environ Control 21: Rutala WA, Barbee SL, Aguiar NC, Sobsey MD, Weber DJ Antimicrobial activity of home disinfectants and natural products against potential human pathogens. Infect Control Hosp Epidemiol 21: Harris LJ, Beuchat LR, Kajs TM, Ward TE, Taylor CH Efficacy and reproducibility of a produce wash in killing Salmonella on the surface of tomatoes assessed with a proposed standard method for produce sanitizers. J Food Prot 64: Akbas MY, Ölmez H Inactivation of Escherichia coli and Listeria monocytogenes on iceberg lettuce by dip wash treatments with organic acids. Lett Appl Microbiol 44: Cutter CN, Dorsa WJ, Siragusa GR Parameters affecting the efficacy of spray washes against Escherichia coli O157:H7 and fecal contamination on beef. J Food Prot 60: Ramos B, Miller FA, Brandão TRS, Teixeira P, Silva CLM Fresh fruits and vegetables-an overview on applies methodologies to improve its quality and safety. Innovative Food Sci Emerging Technol 20: Lee HH Microbial control of fresh-cut cabbage by various pretreatment and packaging methods. PhD Dissertation. Sungshin Women s University, Seoul, Korea. 16. Ministry of Food and Drug safety Korea Food Code. Ministry of Food and Drug Safety, Cheongju, Korea. p Lee S, Moon HK, Lee SW, Moon JN, Lee SH, Kim JK Enhanced antimicrobial effectiveness of Omija (Schizamdra chinesis Baillon) by ClO 2 (chlorine dioxide) treatment. Korean J Food Preserv 20:

9 친환경세척수병합처리가당근주스의미생물안전성에미치는영향 Ding T, Rahman SME, Oh DH Inhibitory effects of low concentration electrolyzed water and other sanitizers against foodborne pathogens on oyster mushroom. Food Control 22: Kim NH, Mun SJ, Kim AH, Min JH, Ahn JH, Ha WH, Kim BI The antimicrobial and anti-plaque effect of dentifrice containing baking soda and triclosan. J Korean Acad Oral Health 35: Fong D, Gaulin C, Lê ML, Shum M Effectiveness of alternative antimicrobial agents for disinfection of hard surfaces. National Collaborating Centre for Environmental Health. Vancouver, Canada. p Rahman SME, Ding T, Oh DH Inactivation effect of newly developed low concentration electrolyzed water and other sanitizers against microorganisms on spinach. Food Control 21: Chang SK, Lee HH, Hong SI, Han YS Effect of organic acid treatment on the quality attributes of buckwheat sprout during storage. Korean J Food Sci Technol 42: Lee SY Microbial safety of pickled fruits and vegetables and hurdle technology. Int J Food Safety 4: Park BK, Oh MH, Oh DH Effect of electrolyzed water and organic acids on the growth inhibition of Listeria monocytogenes on lettuce. Korean J Food Preserv 11: MFDS General test methods. In Korea Food Code. Ministry of Food and Drug Safety, Sejong, Korea. p Park SS, Sung JM, Jeong JW, Park KJ, Lim JH Quality changes of salted Chinese cabbages with electrolyzed water washing and a low storage temperature. J Korean Soc Food Sci Nutr 42: Sun SH, Kim SJ, Kim GC, Kim HR, Yoon KS Changes in quality characteristics of fresh-cut produce during refrigerated storage. Korean J Food Sci Technol 43: Kubheka LC, Mosupye FM, von Holy A Microbiological survey of street-vended salad and gravy in Johannesburg city, South Africa. Food Control 12: Mao L, Que F, Wang G Sugar metabolism and involvement of enzymes in sugarcane (Saccharum officinarum L.) stems during storage. Food Chem 98: Lee SY, Yu HY, Choi DS, Hur SJ A study on the types and growth patterns of microorganisms and quality characteristics in cherry tomatoes and head lettuces according to storage period and temperature. Korean J Food Nutr 26: Torkamani AE Impact of PEF and thermal processing on apple juice shelf life. Iran J Microbiol 3: Li P, Barth MM Impact of edible coatings on nutritional and physiological changes in lightly-processed carrots. Postharvest Biol Technol 14: