KOREAN J. FOOD SCI. TECHNOL. Vol. 41, No. 2, pp. 146~150 (2009) The Korean Society of Food Science and Technology Maltodextrin 을처리한생강절편의탈수, 건조및열풍건조와동결건조된생강과의비교 김민희 김민기 유명식 1 송영복 1 서원준 1 송경빈 * 충남대학교식품공학과, 1 세전 Dehydration of Sliced Ginger Using Maltodextrin and Comparison with Hot-air Dried and Freeze-dried Ginger Min-Hee Kim, Min-Ki Kim, Myung-Shik Yu 1, Young-Bok Song 1, Won-Joon Seo 1, and Kyung Bin Song* Department of Food Science and Technology, Chungnam National University 1 Sejeon Corporation Abstract Sliced ginger samples were dried using 30, 50, and 80% maltodextrin, respectively, as a dehydrating agent. The moisture content of the maltodextrin-treated ginger decreased with increasing concentrations of maltodextrin. The dehydrated ginger was compared with hot air-dried and freeze-dried ginger samples in terms of rehydration ratio, gingerol content, color, and sensory characteristics. The rehydration ratio of the maltodextrin-treated ginger was superior to those of the hot-air dried or freeze-dried ginger. In addition, the maltodextrin-treated ginger had the highest content of 6-gingerol among the samples. Color as well as sensory scores for odor, texture, appearance, and overall acceptance were greater for the maltodextrintreated ginger compared to the hot-air dried or freeze-dried ginger. These results indicate that drying ginger with maltodextrin is very efficient because good rehydration capacity is retained and minimal cell destruction can be achieved. Key words : maltodextrin, dehydration, ginger slice, cytorrhysis 서 생강은아시아가원산지로생강과 (Zingiberaceae) 에속하는다년생초본식물로여러약리작용을가지고있는데, 특히생강의매운맛성분인 6-gingerol 은항염증작용및항산화작용특성을가지며진통제, 해열제, 심장병등에수천년전부터이용되어오고있다 (1-4). 생강의국내생산량은 4 만여톤으로주로향신양념인다대기또는생강차로이용되고있다. 세계적으로는건조된형태로연간 100,000 톤정도이용되고그외 essential oil, oleoresin 등의형태로유통되는데주로식용, 약용및화장품용등으로사용된다. 그러나생강은수확후저장중싹이나거나미생물에의해손상되기쉽고수세나껍질제거와같은처리에의해곰팡이에의한오염에노출되어장기간저장을위한방법의하나로생강절편의건조처리가제시된다 (5-10). 식품의건조는수분제거, 부피감소로인한운송의편리, 미생물로인한손실방지등의장점이있지만건조과정중높은온도에의해식물고유의구조와성질이변화한다. 물리적인변화로인한부피의감소로다공성변화, 수분함유능력감소및 *Corresponding author: Kyung Bin Song, Department of Food Science and Technology, Chungnam National University, Daejeon 305-764, Korea Tel: 82-42-821-6723 Fax: 82-42-825-2664 E-mail: kbsong@cnu.ac.kr Received December 15, 2008; revised February 12, 2009; accepted February 12, 2009 론 미세구조파괴가발생하며, 또한그러한변화에의해산화반응, ph, 이온결합의변화가일어나는데특히초기건조과정에서비효소적갈변화반응으로인한색변화, 세포막단백질등에변화를가져다준다 (11-13). 이러한열풍건조등에의한품질저하를방지하고자사용되는건조방법중의하나인사이토리시스 (cytorrhysis) 현상을이용하는탈수는 polyethylene glycol 이나 maltodextrin 과같은고분자수용성물질을탈수제로사용하는것으로, 탈수제분자들이식물세포벽의세공을통과하지않고식물세포벽에확산압력을가하여탈수시키는방법이다 (14-16). 탈수제가세포내로통과되는삼투압방법과는달리, 사이토리시스탈수방법은탈수효과가뛰어나고세포파괴, 유용성분, 맛과향의변화가적고또한고농도의탈수제로인한미생물에의한변패및산화에의한변질을방지한다고알려져있다 (14-16). 따라서본연구에서는탈수, 건조방법중의하나인사이토리시스원리를이용하여수용성고분자물질이며점도가낮고, 식품첨가제로하용되어있는 maltodextrin 을사용하여생강절편을탈수처리하여건조된생강절편의복원율, 색도, 관능평가등을분석하고또한동결건조, 열풍건조한생강과의품질을비교함으로써, 건조생강절편의유통기한을증대시켜즉석조리식품의부재료로써개발하고자본연구를수행하여그결과를보고하는바이다. 재료및방법 실험재료본실험에사용된생강은서산에서수확한것으로, 대전에있 146
Maltodextrin 을처리한생강절편 147 는대형마트에서구입하여껍질을제거한근경을 1.0±0.5 mm 로절단하여실험재료로사용하였다. Maltodextrin(Grain Processing Co., Muscatine, IA, USA) 은 DE 값이 9-12 인제품을구입하여사용하였다 시료건조절단된생강시료 50 g 에분말형태탈수제 maltodextrin 을시료무게의 30, 50, 80%(w/w) 를각각첨가하여, LDPE bag 에서혼합시킨후 20 o C shaking incubator 에서탈수하였다. 탈수후시료표면의 maltodextrin 을제거하기위해수초간세척한후물기를제거하고잔류수분이완전히제거될때까지 20 o C incubator 에서최종건조하였다. 동결건조는절단된생강시료 50 g 을 70 o C 에서동결시킨후동결건조기 (FD-5508, IlShin Lab Co., Yangjugun, Korea) 를사용하여 50 o C, 0.67 Pa 에서동결건조를실시하였다. 열풍건조는시료 50 g 을열풍건조기 (HB-502LP, Hanbaek Co., Bucheon, Korea) 를사용하여 70 o C 에서 24 시간건조시켰다. 수분함량측정시료의수분함량은 AOAC 방법 (17) 에의해분석하였다. 건조기 (C-DO, Chang Shin Scientific Co., Seoul, Korea) 를이용하여 105±2 o C 에서건조하여분석하였고시료군마다 3 회반복하여측정하였다. 건조하기전생강의수분함량은 89% 였다. 복원율측정건조된고추시료에증류수 200 ml 를넣고 25 o C 항온수조에서 10, 20, 30, 40, 50, 60 분간격으로침지한후무게를측정하여흡수된물무게대비시료건물무게로 (g/g) 복원율을계산하였다. Gingerol 함량측정건조된생강시료 3g을 30초동안 mixer를이용하여분쇄하여 1g 시료를취한후 HPLC 등급의 acetonitrile 20 ml를사용하여추출하였다. 상등액을 10,000 g에서원심분리하고 0.2 µm nylon syringe filter(whatman, Nylon 66 Syringe, 13 mm, 0.2 µm, 100 units Maidstone, England) 를사용하여여과한후 HPLC(Thermo Separation Products Inc., Piscataway, NJ, USA) 로분석하였다. 분석조건은 C18 역상컬럼을이용하고이동상은 water와 acetonitrile을이용하였고 gradient는 acetonitrile이 0-8분에서 45-50%, 8-17분에서 50-65%, 17-32분에서 65-100%, 32-38분에서 100%, 38-40분에서 100-45% 였다. Injection volume은 20 µl, flow rate는 0.5 mm/ min를사용하였으며컬럼을통과하는물질의검출을위해 230 nm 에서흡광도를측정하였다. 통계분석실험결과의유의성검정은 SAS program(18) 을사용하여실시하였고 p<0.05 수준에서 Duncan s multiple range test 방법을사용하여통계처리를하였다. 실험결과는평균 ± 표준편차로나타냈다. 결과및고찰 수분함량측정사이토리시스원리를이용하여탈수한생강절편의수분함량변화를측정하였다. 최적탈수제처리조건수립을위한 maltodextrin 의농도에따른처리후시간별탈수량을측정한결과, maltodextrin 으로처리한생강절편의탈수에있어서처음 4 시간동안급격한감소를보였고, 처리 6 시간후부터탈수속도가감소했으나지속적인수분감소가이루어졌다 (Fig. 1). Sereno 등 (20) 에의해보고된탈수제농도와침지시간에따른탈수속도에관한연구에서도유사한결과가관찰되었다 (19-20). 탈수제처리 8 시간경과후건조된생강절편의수분함량은 74.0, 63.7, 56.3% 로각각나타났는데 20 o C 에서추가건조된최종생강절편의수분함량은 maltodextrin 농도에따라각각 14.2, 10.4, 9.2% 이었다. 이러한결과는, 사이토리시스원리를이용한탈수에있어서탈수제농도가높을수록탈수량이증가하며처리시간이길수록최종수분함량이감소한다는것을알수있었다. 삼투압건조의경우에도삼투압력의차이가클수록세포를압착하는힘이커져탈수효율이좋다고보고된바있다 (16,20). Singh 등 (2) 의보고에의하면저분자물질을이용하는삼투압의경우, 초기단계에서저분자물질들이세포안으로빠르게이동하여탈수속도가빠르나시간이지날수록탈수속도가느려진다고보고하였다 (2). 이러한현상은사이토리시스를이용한건조방법에서도나타났으나, 삼투압의경우농도가평형을이룰때건조가끝나게되는데반하여농도구배를이용한방법이아니므로지속적인건조효과를나타내어삼투압탈수방법보다탈수율이뛰어남을보였다 (2,16). 복원율측정건조된생강절편의복원율에있어서 maltodextrin 처리한생강절편의경우초기 10 분간복원율이급격하게증가하여 30, 50, 색도측정건조된시료의색도측정은표준백판 (L = 97.47, a = 0.02, b = 1.67) 으로보정된 colorimeter(cr-300 Minolta chromameter, Minolta Camera Co., Osaka, Japan) 를사용하여 Hunter L, a 및 b 값을측정하였다. 각시료는 5 회반복하여측정하였다. 관능검사건조된시료를 25 o C 에서 30 분간복원한후훈련된 10 명의패널을사용하여각각복원된시료의향, 색깔, 경도, 외관및전체적인품질을 9 점 hedonic scale 을사용하여관능검사를실시하였다 (9-8: 매우좋음, 7-6: 좋음, 5-4: 보통, 3-2: 나쁨 1: 매우나쁨 ). Fig. 1. Changes in moisture content of ginger slice by addition of maltodextrin. Bars represent standard error., maltodextrin 30%;, maltodextrin 50%;, maltodextrin 80%.
148 한국식품과학회지제 41 권제 2 호 (2009) 80% 농도별로각각 3.45, 4.04, 4.73 g/g 값을나타냈고 60 분후에는 6.76, 7.56, 7.91 g/g 값을보였다 (Fig. 2). 동결건조의경우초기 10 분동안 maltodextrin 30, 50% 처리보다는높았으나 80% 보다는낮은값을보였고또한초기복원속도는빠르나시간이지날수록복원속도가감소하여 60 분후 6.63 g/g 의값을나타냈다. 그리고열풍건조의경우 60 분후복원이완료되었으며최종복원울이 6.35 g/g 을나타냈다. 본연구결과, 복원율이가장좋은것은 maltodextrin 으로처리한것으로열풍건조나동결건조보다우수하였고, 특히 maltodextrin 80% 처리한것은열풍건조와의비교에서 1.56 g/g 의차이를나타냈다 (Fig. 2). 또한 maltodextrin 의농도간의차이는 80% 와 30, 50% 의차이를보면 1.15, 0.35 로농도가높을수록생강절편의복원율이좋다는것을알수있었다. 건조된식물세포의수축은식품의완전한복원을이루어지지않게하기때문에건조전에당, 글리세롤등을처리하여세포벽에있는다당류의수소결합을보존하여세포벽의파괴를최소화한다 (21). Maltodextrin 을처리한생강절편의경우 maltodextrin 이탈수, 건조중이와같은작용을하여식물조직의파괴를감소시킨것으로판단된다. 또한열풍건조의경우높은온도처리에따른세포수축으로인해세포파괴가발생하여복원율이좋지않다는기존다른연구보고와도일치한다 (21-23). Gingerol Gingerol 은생강의대표적인지표성분으로높은온도등가공, 저장조건에따라생화학적활성이다른 shogaol 이나다른성분으로변화므로생강의품질지표로사용된다 (2). Maltodextrin 을 Fig. 2. Rehydration ratio of dried ginger slice. Bars represent standard error., maltodextrin 30%;, maltodextrin 50%, maltodextrin 80%;, freeze drying, hot air drying Table 1. Gingerol content of freeze dried, hot air dried, and maltodextrin-treated ginger slice Gingerol(mg/g) Control 0.32±0.016 1) a2) Freeze drying 0.16±0.013 c Hot air drying 0.13±0.004 c Maltodextrin (30%) 0.05±0.001 d Maltodextrin (50%) 0.11±0.004 c Maltodextrin (80%) 0.24±0.012 b 1) Raw ginger slice 2) Any means in the same column followed by different letters are significantly different (p<0.05). 처리하여탈수, 건조된생강절편의 gingerol 함량에있어서 maltodextrin 의처리농도 30, 50, 80% 별로 0.05, 0.11, 0.24 mg/g 으로나타나 maltodextrin 처리농도가높을수록 gingerol 함량이많았다. 또한동결건조, 열풍건조에비해서도 maltodextrin 80% 처리생강절편의 gingerol 함량이높았고, 열풍건조의경우는가장낮은 gingerol 함량을나타냈다. Bhattarai 등 (2) 에의한처리온도에따른생강의 gingerol 함량변화의연구결과에서도온도가높을수록 gingerol 함량의손실이크다고보고되었다 (2). 색도측정건조방법에따른생강의색도측정은 L 값의변화에따라 a, b 값도변화한다는연구보고 (25) 가있는데, Hunter L 값의경우 maltodextrin 농도별로처리한것에서는유의적인차이가나타나지않는반면에열풍건조의경우대조구와비교하여낮은 L 값을가졌다 (Table 2). Jayaraman 등 (21) 의연구에의하면열풍건조의경우높은온도에의한영향으로갈변현상이일어난다고보고하였는데, 그결과생강표면에영향을미쳐열풍건조된생강절편의 lightness 가감소하는것을알수있었다. Hunter a 값의경우대조구 -8.58 와비교하여동결건조와열풍건조처리한생강절편의값이 maltodextrin 을처리한생강절편에비하여낮았고, 또한 b 값의경우대조구와비교해서동결건조, 열풍건조처리한생강절편이 maltodextrin 을처리한것에비해낮아, maltodextrin 을처리한생강절편의색도가잘보존됨을보여주었다. 본연구결과와마찬가지로 Saravacos 등 (24) 의열풍건조한바나나, 당근, 감자및사과를이용한연구에서도 L, a, b, 값이대조구에비해변화가큰것으로나타났다는연구결과는열풍건조에따른품질저하를보여준다. 동결건조역시열풍건조보다변화가적게일어났지만여전히색도에있어서변화가있었고, maltodextrin 으로처리한생강절편만이 L, a, b 값에있어서적게변화하여품질저하가적다는것을알수있었으며, 또한 L, a, b 값으로부터계산한 E 값에서도 maltodextrin 으로처리한생강절편이대조구와비 Table 2. Hunter color values of freeze dried, hot-air dried, and maltodextrin-treated ginger slice Color parameter L a b E Control 83.63±2.10 c1) 8.58±0.75 d 43.10±0.93 a 000.0±0 Freeze drying 89.45±0.59 a 3.50±0.40 a 35.55±4.54 b 10.80±1.3 b Hot air drying 78.89±2.72 d 2.62±0.71 a 24.23±4.09 c 20.35±1.1 a Maltodextrin (30%) 86.27±0.79 b 7.65±0.42 cd 40.34±3.96 cd 03.93±1.86 c Maltodextrin (50%) 86.67±0.45 b 6.60±0.60 b 39.34±0.68 b 05.22±1.6 c Maltodextrin (80%) 86.65±0.99 b 7.55±0.87 cb 40.74±2.96 ba 03.97±1.9 c 1)Any means in the same column followed by different letters are significantly different (p<0.05).
Maltodextrin 을처리한생강절편 149 Table 3. Sensory evaluation of freeze dried, hot air dried and maltodextrin-treated ginger slice Organoleptic parameter Color Odor Texture Appearance Overall Control 9.00±0.00 a1) 9.00±0.00 a 9.00±0.00 a 9.00±0.00 a 9.00±0.00 a Freeze drying 5.86±1.07 b 6.50±0.76 b 3.65±0.95 c 5.00±1.07 c 5.50±0.54 d Hot air drying 3.43±0.79 c 4.88±0.64 b 4.00±1.07 c 3.38±0.74 d 4.25±0.71 e Maltodextrin (30%) 6.71±1.10 b 7.13±0.60 b 6.75±0.50 b 7.13±0.60 b 6.88±0.80 b Maltodextrin (50%) 6.71±0.80 b 6.75±0.70 b 6.50±1.30 b 7.00±1.10 b 6.75±1.00 cb Maltodextrin (80%) 6.29±0.95 b 6.63±1.19 b 5.88±0.83 b 6.50±0.53 b 6.00±1.07 cd 1) Any means in the same column followed by different letters are significantly different (p<0.05). 으며, 열풍건조와는뚜렷한차이를보였다 (Table 3). 조직의경우동결건조된생강절편의평가가가장낮았는데동결되는동안얼음결정이세포벽에손상을주기때문인것으로판단된다 (14). 외관의평가역시 maltodextrin 농도별로유의적인차이는나타나지않았으며열풍건조처리가가장낮은평가를받았다. 이것은건조당시수축현상과관련이있는데, Azian 등 (26) 의보고에따르면스팀을처리하여건조한생강의조직에있어서전분성분이수축하여세포벽이파괴된다고보고한바있다 (22,26). 종합적기호도역시동결, 열풍건조에비하여 maltodextrin 을처리한생강절편이우수하였으나농도별로는유의적인차이를보이지않았다. 따라서 maltodextrin 처리한생강절편의관능평가결과는동결건조나열풍건조보다품질면에서우수함을보여준다. 요 약 Fig. 3. Photos of maltodextrin-treated ginger slice before and after rehydration. (a) Dried ginger slice and (b) after rehydration of dried ginger slice 교하여동결건조와열풍건조보다차이가작음을보였다 (Table 2). 관능평가건조된생강절편의품질을관능적으로평가하기위하여색도, 향기, 조직, 외관및종합적기호도로 9 점 hedonic scale 을사용하여관능평가를실시하였다 (Table 3). 색도의경우, maltodextrin 농도별로비교한경우유의적인차이가나타나지않았으나동결건조, 열풍건조와는차이를보였다. 향기의경우 maltodextrin 30% 를처리한생강절편이대조구와비교하여가장우수하였고 maltodextrin 의처리농도가낮을수록향기가좋음을알수있었 Maltodextrin 30, 50, 80% 의농도로생강절편을처리하여탈수, 건조하였는데 maltodextrin 농도가높을수록탈수효율이좋았으며 80% maltodextrin 처리된생강은최종수분함량이 9.21% 로가장탈수율이좋았다. Maltodextrin 처리로건조한생강을복원율, gingerol 함량, 색도, 관능평가측면에서열풍, 동결건조된생강과비교한결과, maltodextrin 80% 처리한생강의복원율이 7.91 g/g 로열풍, 동결건조한생강보다복원율이뛰어났다. Gingerol 함량은 maltodextrin 농도가높을수록함량이많았는데 maltodextrin 80% 처리한것이 1.19 mg/g 로가장뛰어났다. 색도의 L, a, b 값은 maltodextrin 농도별로유의적인차이는나타나지않았고대조구와비교해서유사한경향을나타냈다. 관능평가에서도색도, 향, 조직, 외관, 종합적기호도에서 maltodextrin 처리시료가다른건조방법에비해서보다좋은결과를나타냈다. 그러므로본연구결과, maltodextrin 을처리하여탈수, 건조하는방법이생강절편의건조에있어서복원율등품질과비용측면에서열풍건조나동결건조방법보다우수한방법이라고판단된다. 감사의글 본연구는농림기술관리센터 (ARPC) 의연구비지원에의해수행되었습니다. 문 1. Alfaro MJ, Bëlanger JMR, Padilla FC, Parë JRJ. Influnce of solvent, matrix dielectric properties, and applied power on the liquid-phase microwave-assisted processes (MAP TM ) 1 extraction of ginger (Zingiber officinale). Food Res. Int. 36: 499-504 (2003) 2. Bhattarai S, Tran VH, Duke CC. The stability of gingerol and 헌
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