김재원 이신호 노홍균 홍주헌 박창수 윤광섭 ABSTRACT This study was performed to determine the effects of pretreatment (: non-treatment, : boiling treatment with 3% sodium chloride, : dipping treatment in glycerol) and drying methods (sun drying, hot air drying, and cold air drying) on the physicochemical properties and antioxidant activities of dried jujube (Zizyphus jujuba Mill.) fruits. Our results show that moisture content is lower (P<0.05) with, and that moisture content is lower with hot air drying compared to other drying methods. The bulk density was highest with. The soluble solids content was highest with. Additionally, the soluble solids content were highest in the following order: hot air drying> cold air drying> sun drying. The titratable acidity of hot air drying was highest of all the drying methods. The titratable acidity was higher with and, and the brix and acid ratio of sun drying was higher than other drying methods. Among the drying methods, showed the best browning-retarding effect, whereas boiling treatment affected quality and color. The total polyphenol content from hot air drying and or treatment was relatively higher than the content from. The flavonoid content was highest with, and all dried jujube showed relatively high antioxidant activities. The sensory evaluation results indicated that the organoleptic scores for overall preference were higher in the and treatment groups. These results suggest that pretreatment and drying methods affect the quality of dried jujube fruit, and show that glycerol treatment with hot air drying can be applied to the production of high quality dried jujube. Key words: dried jujube, quality characteristics, pretreatment, drying method 서 대추는갈매나무과 (Rhamnaceae) 에속하는낙엽활엽교 목의열매로서중국계대추 (Zizyphus jujube Miller) 와인 도계대추 (Zizyphus mauritiana Lam) 등생태형이전혀다 른 2 종으로분류되며, 중국계대추의경우우리나라를비롯 한아시아남부및동부, 유럽서남부지역에서재배되고 있다 (1). 우리나라에서는재래종인묏대추 (Zizyphus jujuba Milller), 대추 (Zizyphus jujuba var. intermis Rehder), 보 은대추 (Zizyphus jujuba forma hoonensis) 등 1 속 3 종류의 재래종이주로분포하고있으며, 개량종인월출, 금성, 무등 대추등이일부지역에서재배되고있다 (2). 대추는강장작용 (3), 항암 (4), 항염증 (5), 결핵, 기관지염및신경쇠약치료효 과 (6) 등의효능이있는것으로알려져약용으로도이용되고 있으며, 과용에따른부작용이없으면서도약용성분과기능 론 Received 8 April 2013; Accepted 23 July 2013 Corresponding author. E-mail: ksyoun@cu.ac.kr, Phone: 82-53-850-3209 성성분을다량함유하고있는약선식품으로인스턴트식품의섭취가많은현대인의건강에도움이되는식품중의하나로여겨지고있다. 특히당질과 ascorbic acid가다량함유되어있고, 약용성분으로는각종 sterols, alkaloids, saponins, vitamins, 유기산류및 amino acids 등이함유되어있는것으로보고 (7) 됨에따라다과, 대추차, 기타식품가공에널리이용되는등건강지향적식품개발이다양하게진행되고있다. 그러나저장성이좋지못하기때문에수확시기에생과형태로일부소비되고, 대부분은건과형태로소비가이루어지고있으나저장및가공방법개발이미진하여품질저하와경제적손실이따르고있는실정이다 (8). 일반농가에서는대추를건조시키기위하여천일건조및열풍건조방법을활용하고있는데, 천일건조는장기간의건조과정중에열화현상이일어나과육의감소와건대추의중량을감소시키고갈변및영양소의파괴로인한품질저하를초래하는이유로열풍건조가주로행해지고있다. 열풍건조의경우는신속하고균일하게건조가이루어져경제적이긴하지만수분손실에기인된수축현상, 빠른건조에의한표면
전처리조건및건조방법에따른건조대추의품질특성및항산화활성 경화현상, 건조물의재수화시낮은복원율, 갈색화반응으로인한색상변화, 조직감, 맛및영양가저하등의문제점이동반된다 (9). 한편농가에서는고추의건조특성에의거하여대추를건조할뿐건조방법및건조조건에대한연구가미흡하여효율적인건조공정을수행하지못하고있는실정이며생산농가뿐만아니라국가의경제적손실을초래하므로건조조건에대한연구개발이요구되고있다. 건조식품의경우건조조건에따른물리 화학적변화가유발되어품질열화가발생하게되는데이를감소시키기위한부가적인방법으로전처리후건조함으로써품질손상을억제하고기호성을증대시키기위한다양한방법들이식품에적용되고있다. 끓는물이나 steam, microwave를이용한 blanching 방법 (10), sulfiting agent 처리하는방법 (11), ascorbic acid, citric acid 등의유기산을이용하여 ph를낮추거나항산화제를이용한전처리방법 (12), 삼투처리나 dipping 등의전처리방법 (13) 등으로이러한기술을농산물의건조공정에도입함으로써효율적인건조기술을획득할수있고고품질의건조농산물을생산함과아울러산업화된기술및제품의개발에많은기여를할수있을것으로전망된다. 따라서본연구에서는고품질의건조대추를얻기위한방법으로 blanching이나삼투처리, dipping과같은전처리방법을다양한건조방법에응용하여건조효율및품질의향상을기하고각전처리및건조방법에따른품질을고찰하여대추의건조효율및품질향상에기여하고자하였다. 재료및방법재료본실험에사용된재래종묏대추 (Zizyphus jujube Miller) 는 2010년 10월경북청도군금천면에서재배한완숙과실을채취하였으며, 수확직후흙이나먼지등의이물질을제거하고 4 C의저장실로옮긴후각각의조건에따라즉시전처리와건조를하였다. 하여 65 C의온도에서 30시간건조하였다. 냉풍건조는냉풍건조기 (JJ-1000, Chunjin E&C Co., Gyeongsan, Korea) 를사용하여냉풍의온도를 35 C로하여 4일간건조하였다. 수분함량및가밀도수분함량은적외선수분측정기 (HG53, Mettler Toledo, Greifensee, Switzerland) 를이용하여측정하였다. 가밀도는건조대추의무게를칭량한후메스실린더로옮겨일정량의증류수를채워부피를측정하고무게를부피로나누어가밀도를나타내었다 (14). 가용성고형분함량, 적정산도및당산비가용성고형분의측정은 Kim 등 (15) 의방법에준하여시료 3 g을취해 30 ml의증류수를가한후 homogenizer (Nissei AM-12, Nohonseiki kaisha Co., Tokyo, Japan) 로 10,000 rpm에서 10분간마쇄하여 20 C에서 2시간방치후여과하여 hand refractometer(n1, Atago, Tokyo, Japan) 를이용하여측정하였다. 적정산도는시료 5 g을취해 50 ml의증류수를가한후 homogenizer(nissei AM-12, Nohonseiki kaisha Co.) 로 10,000 rpm에서 10분간마쇄하여 20 C에서 3시간방치한다음여과하여 0.01 N NaOH로적정하여소비된양을 citric acid로환산하였으며, 대추의가용성고형분함량 / 적정산도값을당산비로하였다. 갈변도및색도갈변도는각각의방법으로전처리한건조대추 2 g에증류수 40 ml를가하고 10% trichloroacetic acid 10 ml를가한다음상온에서 2시간방치한후여과하여 420 nm에서흡광도를측정하였다 (16). 색도는표준백색판으로보정된 chromameter(chromameter CR-200, Minolta, Tokyo, Japan) 를이용하여측정하였으며, 건조대추의색도는건조후분말화시킨과육의색차를 Hunter scale에의한 L (lightness), a(redness-greenness) 및 b(yellownessblueness) 값을측정하였다. 전처리및건조방법건조전전처리방법과처리조건은예비실험을통하여결정하였으며, 건조효율을증대할수있는건조전처리방법을선정하여건조방법에따른품질평가를실시하였다. 전처리방법으로 blanching 처리는 3% NaCl을함유하는열수 (95 C) 에서 30초간, dipping 처리는 glycerol 용액에서 10 분간처리하였으며각각의시료는전처리후즉시흐르는냉수에수세한다음물기를제거하여건조하였다. 각각의건조방법에따른건조시간은예비실험을바탕으로과도한건조및품질변패가발생하지않는일정구간을설정하여건조를행하였다. 천일건조는일광을이용하여 20일간일정수분함량이될때까지건조하였으며, 열풍건조는적외선열풍건조기 (IRD-250, Woori Sci, Pocheon, Korea) 를사용 시료의추출전처리및건조방법에따른건조대추의항산화성분함량및활성을비교하기위하여시료를 70% 에탄올용매에 1:10의비율로넣고상온에서 3일간추출한후 Whatman No. 2(Whatman plc, Kent, UK) 여과지로여과하여얻은여액을분석용시료로사용하였다. 폴리페놀함량측정폴리페놀함량은 Dewanto 등 (17) 의방법에따라추출물 100 μl에 2% sodium carbonate 2 ml와 50% Folin- Ciocalteu reagent 100 μl를가한후 720 nm에서흡광도를측정하였으며 gallic acid(sigma-aldrich Co., St. Louis, MO, USA) 의검량선에의하여함량을산출하였다.
김재원 이신호 노홍균 홍주헌 박창수 윤광섭 플라보노이드함량측정플라보노이드함량은 Saleh와 Hameed(18) 의방법에따라추출물 100 ml에 5% sodium nitrite 0.15 ml를가한후 25 C에서 6분간방치한다음 10% aluminium chloride 0.3 ml를가하여 25 C에서 5분간방치하였다. 다음 1 N NaOH 1 ml를가하고교반후 510 nm에서흡광도를측정하였으며 rutin hydrate(sigma-aldrich Co.) 의검량선에의하여함량을산출하였다. DPPH radical 소거활성측정 Blois(19) 의방법에따라추출물 0.2 ml에 0.4 mm DPPH (1,1-diphenyl-2-picryl-hydrazyl) 용액 0.8 ml를가하여 10분간방치한다음 525 nm에서흡광도를측정하였으며 DPPH radical scavenging ability(%)=100-[(o.d of sample/ O.D of control) 100] 에의하여활성도를산출하였다. A radical 소거활성측정 Re 등 (20) 의방법에따라 7.4 mm A[2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] 와 2.6 mm potassium persulfate를혼합하여실온 암소에서 24시간동안방치하여 radical을형성시킨다음실험직전에 A 용액을 732 nm에서흡광도가 0.700 ±0.030이되도록 phosphate buffer saline(pbs, ph 7.4) 으로희석하여사용하였다. 희석된용액 950 μl에추출물 50 μl를가하여암소에서 10분간반응시킨후 732 nm에서흡광도를측정하였으며계산식, A radical scavenging ability(%)=100-[(o.d of sample/ O.D of control) 100] 에의하여활성을산출하였다. 관능검사관능검사는실험목적과관능적품질요소를잘인지하도록훈련시킨식품공학을전공하는대학원생및학부생 20명 으로구성된관능요원에의하여 5점채점법 (5: very much like or strong, 1: very much dislike or weak) 에의하여실시하였고외관 (appearance), 색 (color), 조직감 (texture), 맛 (taste) 및전반적인기호도 (overall acceptability) 에대한관능특성을평가하였다. 통계처리모든실험은 3회반복으로행하여평균치와표준편차로나타내었고, 유의성검증은 version 12의 SPSS(12, SPSS Inc., Chicago, IL, USA) software를이용하여 Duncan's multiple range test를행하였다. 또한갈변도, 항산화물질및항산화활성간의상관관계는 Pearson's correlation analysis를통하여분석하였다. 결과및고찰수분함량, 가밀도, 가용성고형분함량, 적정산도및당산비 전처리 (non-treated, NaCl boiling, glycerol dipping) 및건조방법 (sun drying, hot air drying, cold air drying) 에따른건조대추의수분함량, 가용성고형분함량, 적정산도및당산비를측정한결과는 Table 1과같다. 건조방법에따라수분함량은뚜렷한차이를나타내었는데천일건조에서는 20일, 열풍건조는 30시간, 냉풍건조의경우 4일정도의건조시간이소요되는것으로나타났다. 전처리방법중 glycerol로전처리한것이유의적으로낮은수분함량을나타내어건조효율이우수한것으로나타났다. 이는전처리직후의수분함량이다른전처리에비하여낮게나타나는것으로보아침지시 wax 층의분해가어느정도이루어짐에따른결과라여겨지나, 추가적인연구와건조가공효과의검증이필요한것으로판단된다. 한편 NaCl boiling 처리의경우도전처리방법으로의활용가능성이있는것으로확인되었다. 건조대추의부피를나타내는가밀도는 NaCl boiling 처리에서가장높았는데건조대추의단위부피당중량이 Table 1. Physicochemical properties of various dried jujube by different pretreatment method Drying method Pretreatment 1) Moisture content (%) 13.06±0.52 3)aA4) 10.67±0.23 bcb 10.17±0.14 cdb 10.97±0.54 ba 7.78±0.16 fb 7.28±0.35 fb 9.57±0.25 da 8.59±0.28 eb 7.33±0.47 fc Bulk density (g/ml) 0.617±0.003 cb 0.652±0.006 ba 0.560±0.002 ec 0.660±0.007 bb 0.830±0.005 aa 0.618±0.006 cc 0.587±0.008 db 0.655±0.008 ba 0.568±0.012 ec Soluble solids content ( Bx) 6.50±0.10 fa 6.35±0.05 gb 6.60±0.01 ea 6.85±0.02 dc 7.01±0.02 cb 7.30±0.01 aa 6.79±0.02 db 6.63±0.06 ec 7.20±0.00 ba Titratable acidity (%) 1.21±0.01 fa 1.01±0.01 hc 1.15±0.02 gb 1.64±0.01 bb 1.52±0.00 cc 1.69±0.01 aa 1.34±0.01 da 1.13±0.01 gc 1.25±0.01 eb Brix and acid ratio (SS/TA) 2) 5.39±0.10 dc 6.31±0.09 aa 5.76±0.12 cb 4.17±0.02 hc 4.62±0.03 fa 4.33±0.02 gb 5.08±0.02 ec 5.89±0.01 ba 5.75±0.05 cb 1), non-treatment;, boiling treatment with 3% sodium chloride for 30 sec;, dipping treatment in glycerol for 10 min. 2) SS/TA=soluble solids content/ titratable acidity. 3) Values are means±standard deviation of determinations. 4) Different superscripts within the whole column (a-h, all groups) and each column (A-C, pretreated groups) indicate significant
전처리조건및건조방법에따른건조대추의품질특성및항산화활성 많이나가무게면에서는유리하나부피면에서는불리한것으로관찰되었으며, glycerol 전처리의경우모든건조방법에서유의적으로낮은가밀도를나타내었다. 가용성고형분의함량의경우열풍건조 (6.85~7.30 Bx) 가천일건조 (6.35~6.60 Bx) 와냉풍건조 (6.63~7.20 Bx) 에비해높은함량을나타내었으며전반적으로 glycerol 침지에서유의적으로높은함량을나타내었다. 이와같은결과는중량감소, 수분손실에따라과실내부의고형분함량이증대된다는보고 (21) 로미루어볼때수분함량의차이에따른결과로사료된다. 한편 NaCl boliing 처리의경우 glycerol 침지에비해다소낮은가용성고형분함량을나타내는것은고온에서삼투작용에의한고형분의손실이발생하는것으로여겨진다. 적정산도는열풍건조가타건조방법에비해높은값을나타내었으며, 전처리에따라서는무처리및 glycerol 침지에서높은경향을나타내었다. 반면 boiling 처리를함에따라대추고유의산도는저하되는것으로나타났다. 당산비의경우천일건조에서가장높았으며다음으로냉풍건조, 열풍건조순으로나타났고, 전처리에따라서는 NaCl boiling> glycerol> 무처리순으로높은함량을나타내었다. 이상의결과전처리및건조방법에따른건조대추의건조효율및품질의차이는건조온도와시간에따른수분손실, 가용성고형분및유기산의용출에인한결과로판단되며, glycerol 침지후열풍건조한건조대추의경우건조온도에의한품질손상을최소화하고건조시간을단축시켜고비용의전력소모를절감시키는효과가있을것으로판단된다. 갈변도및색도과실류의갈변현상은 polyphenoloxidase(ppo) 와같은효소에의한페놀성물질의산화에의해서발생되며건조시온도에의한 maillard 반응또한갈변의주원인이라고할수있다. 건조대추의색도를나타내고자전처리및건조방법에따른갈변도및색도를측정한결과는 Table 2와같다. 갈변도는열풍건조, 냉풍건조, 천일건조순으로, 전처 리방법에따라서는 NaCl boiling, 무처리, glycerol 침지순으로높은값을나타내었다. 천일건조에서전반적으로갈변되는정도는낮은경향을보였으며, 이는열에노출되는정도와온도차이에따른결과로판단된다. 특히 NaCl boiling 처리의경우가장낮은갈변도를나타내었는데고온의전처리가갈변관련효소를불활성화 (22) 시켜건조온도에의한갈색물질의형성을저해시키는것으로나타났다. 적색도는무처리가 NaCl boiling 및 glycerol 침지에비해유의적으로높은경향을나타내어 maillard 반응과비효소적갈변반응 (23) 이영향을미치는것으로나타났으며, boiling 처리한건조대추의경우적색도는감소하고황색도는증가하는것으로나타나전반적으로퇴색한색을동반하고기호성이저하되는것으로나타났다. 폴리페놀, 플라보노이드및 DPPH, A 라디칼소거활성전처리및건조방법에따른건조대추의폴리페놀, 플라보노이드, DPPH 및 A 라디칼소거활성을비교한결과는 Table 3과같다. 건조방법에따른폴리페놀함량은열풍건조 (4.19~5.48 mg/g)> 냉풍건조 (4.34~4.67 mg/g)> 천일건조 (3.45~3.92 mg/g) 순으로나타났으며, 전처리방법간에는무처리및 glycerol 침지가 NaCl boiling 처리에비해유의적으로높은함량이검출되었다. 플라보노이드함량의경우모든건조방법의 boiling 처리구에서높은함량이검출되어열처리시페놀성화합물이변형되어그함량이감소된다는보고와는상반된결과를나타내었다 (24). 일반적으로페놀성물질의경우수용성과불용성으로구분이되며삼투압및열적처리시일정유용성분또한함께빠져나갈수있는것으로알려지고있다 (25). 한편적정열처리및특정조건에서는불용성 phenol계화합물이고분자화합물로부터유리되어유리형화합물로분해됨에따라가용성물질의용출이용이해지는것으로보고되고있다 (26). 따라서 boiling 처리에서폴리페놀함량이감소되는현상은유용성분이용출됨에따른결과라사료되며, 플라보노이드함량의증대 Table 2. Browning degree and color properties of various dried jujube by different pretreatment method Drying method Pretreatment 1) Browning degree (O.D 420 nm) 0.234±0.002 2)fB3) 0.231±0.002 fb 0.267±0.002 ea 1.072±0.002 bb 0.384±0.002 dc 1.103±0.006 aa 0.454±0.011 ca 0.275±0.011 eb 0.459±0.001 ca Hunter's color value L (lightness) a (redness) b (yellowness) 24.52±0.66 bb 25.90±0.18 aa 22.72±0.42 dec 21.81±0.19 eb 24.31±0.70 bca 23.99±0.39 bca 23.86±0.97 bcab 23.37±0.11 cdb 24.80±0.54 ba 19.07±0.63 aa 16.22±0.29 bb 15.93±0.85 bcb 15.03±1.48 bca 12.69±0.63 db 13.14±0.59 dab 17.83±0.59 aa 14.63±0.85 cb 15.59±0.57 bcb 6.62±0.24 cdb 8.31±0.28 aa 5.93±0.99 defb 4.98±0.70 fb 6.95±0.34 cda 5.34±0.56 efb 6.34±0.98 cdeb 8.93±0.88 aa 7.56±0.57 bcab 1) Abbreviation: See Table 1. 2) Values are means±standard deviation of triplicate determinations. 3) Different superscripts within the whole column (a-f, all groups) and each column (A-C, pretreated groups) indicate significant
김재원 이신호 노홍균 홍주헌 박창수 윤광섭 Table 3. Antioxidant component and activity of various dried jujube by different pretreatment method Drying method Pretreatment 1) Polyphenols (mg GAE 2) /g) 3.92±0.08d 4)deA5) 3.45±0.16 fb 3.68±0.15 efab 5.48±0.18 aa 4.19±0.15 cdb 5.45±0.12 aa 4.42±0.16 bca 4.34±0.23 ca 4.67±0.16 ba Flavonoids (mg RHE 3) /g) 0.49±0.12 eb 1.22±0.06 ba 0.63±0.13 deb 0.91±0.15 cb 1.64±0.15 aa 0.83±0.12 cdb 0.84±0.13 cdb 1.59±0.21 aa 1.00±0.13 bcb DPPH radical scavenging ability (%) 32.11±1.03 gc 52.20±0.79 fa 34.35±0.68 gb 77.70±2.18 aa 73.82±2.96 ba 76.85±2.09 aa 59.93±1.55 ec 69.27±1.75 ca 64.57±1.53 db A radical scavenging ability (%) 55.34±1.94 gc 81.59±0.90 ea 66.86±2.11 fb 92.97±2.10 abcab 90.53±1.78 cdb 94.29±0.64 aba 89.08±1.67 db 91.49±1.42 bcdb 95.91±1.53 aa 1) Abbreviation: See Table 1. The concentrations of samples (DPPH and A radical scavenging ability) solutions were measured at 50 mg/ml. 2) GAE: gallic acid equivalents. 3) RHE: rutin hydrate equivalents. 4) Values are means±standard deviation of triplicate determinations. 5) Different superscripts within the whole column (a-g, all groups) and each column (A-C, pretreated groups) indicate significant Table 4. Sensory evaluation of various dried jujube by different pretreatment method Drying method Pretreatment 1) Appearance Color Texture Taste 3.70±0.82 2)abA3) 2.20±0.79 cb 3.20±0.63 aba 3.50±0.85 aba 3.00±0.67 ba 3.70±0.82 aba 3.60±0.52 aba 3.80±0.63 aa 3.80±0.79 aa 3.20±0.92 abca 2.40±0.84 db 2.80±0.63 cdab 3.80±0.63 aba 2.60±0.84 cdb 3.40±0.70 abcab 3.10±0.74 bcb 3.30±0.48 abcab 3.90±0.74 aa 3.10±0.57 aba 2.50±0.85 bca 2.80±0.63 abca 2.90±0.74 aba 2.20±0.63 cb 3.30±0.67 aba 3.20±0.63 aa 3.00±0.67 aba 3.20±0.63 aa 3.10±0.99 bcda 2.10±0.74 eb 3.00±0.67 cda 3.80±0.63 aba 2.60±0.70 deb 3.90±0.74 aa 3.40±0.70 abca 3.10±0.74 bcda 3.60±0.52 abca Overall acceptability 3.00±0.47 bca 1.80±0.63 db 2.90±0.74 bca 3.70±0.48 aa 2.70±0.67 cb 3.80±0.63 aa 3.50±0.71 abab 2.90±0.57 bcb 3.80±0.92 aa 1) Abbreviation: See Table 1. 2) Values are means±standard deviation of triplicate determinations. Sensory scores of all attributes for three pooled sample were evaluated by 20 panels from none at all (1 point) or dislike extremely (1 point) to very strong (5 points) or like very much (5 points). 3) Different superscripts within the whole column (a-e, all groups) and each column (A-B, pretreated groups) indicate significant 는열처리에의한 phenol계유도체의가용화가용이해짐에따른결과로추측된다. 유용성분의함량과항산화활성간의관계는다소차이는있으나전반적으로폴리페놀및플라보노이드함량이높음에따라활성또한높아지는양의관계를나타내었으며, 열풍건조가천일건조및냉풍건조에비해유의적으로높은라디칼소거활성을나타내었다. 초기식품의건조시열이가해지면아미노산의 peptide, 단백질의 α- amino group과당의반응에의한비효소적갈변반응이주로일어나며, 적정열처리가가해질경우식품성분내환원당과질소화합물의갈색화반응을일으키고생성된산물은항산화효과를가진다고보고된바있다 (27). 따라서본연구에서열풍건조처리한대추에서높은저해활성을나타내는것은높은갈변화로인한생성된산물과관련이있는것으로해석되며, 이러한활성의증가는건조시열에의하여 furan, pyrol 등의유도체, reducton류, 알돌형축합반응에의해생성된 maillard 생성물질에기인한결과와관련이있 는것으로사료된다 (28). 관능검사전처리및건조방법에따른건조대추의품질을평가하기위한방법으로관능검사를실시하였으며그결과는 Table 4와같다. 건조방법에따른외관및색도는냉풍건조와열풍건조에서전반적으로높은기호도를나타내었고전처리방법간에도유의적인차이를보였는데, 천일건조, 열풍건조의경우는무처리에서높은기호도를, 냉풍건조는 glycerol 침지에서높은기호도를나타내었다. 한편 NaCl boiling 처리는가장낮은점수를얻어외관과함께품질이가장떨어지는것으로관찰되었으며, 조직감과맛또한 boiling 처리에서가장낮은점수를얻어기호성이떨어지는것으로나타났다. 반면 glycerol 처리의경우조직감과맛이무처리와유사하거나기호도가증대되는결과를나타내어관능적품질을향상시키는것으로나타났다. 종합적기호도는 glycerol
전처리조건및건조방법에따른건조대추의품질특성및항산화활성 Table 5. Correlation coefficients among browning degree, titratable acidity, total polyphenol content, DPPH and A radical scavenging ability of various dried jujube by different pretreatment method Factor 1) BD TA TPC DPPH A BD TA TPC DPPH A 0.869 ** 0.930 ** 0.846 ** 0.667 * 0.674 * 0.751 * 0.527 0.479 0.632 0.930 ** 1) BD, browning degree; TA, titratable acidity; TPC, total polyphenol content; DPPH, DPPH radical scavenging ability; A, A radical scavenging ability. * P<0.05, ** P<0.01. 침지가가장기호성이높은것으로조사되었으며다음으로 무처리, boiling 순이었다. 이상의결과로볼때 boiling 처리 는건조효율에서는우수하였으나품질면에서기대할만한 수준이되지는못한반면 glycerol 용액에침지하여열풍건 조한경우건조효율의증대는물론품질도우수한것으로 나타났다. 따라서전처리에따른유용성분의함량, 건조효율 및영양적가치를고려하였을때 glycerol 전처리와열풍건 조방법을효과적으로이용하는것이건조효율의증대및 품질의손상을최소화함에따른고품질의건조대추를제조 할수있는방안이될것으로기대된다. 갈변도, 항산화물질및항산화활성간의상관관계 전처리및건조방법에따른건조대추의갈변도, 항산화성 분과활성간의상관관계를분석한결과는 Table 5 와같다. 갈변도가높을수록적정산도, 총폴리페놀함량, 전자공여능 이높았으며, 상관계수는각각 0.869(P<0.01), 0.930(P< 0.01), 0.667(P<0.05) 로양의상관관계를보였다. 적정산도 가높을수록폴리페놀함량, 전자공여능이높았으며, 상관계 수는각각 0.846(P<0.01) 및 0.674(P<0.05) 로양의상관관 계를나타내었다. 그리고폴리페놀함량과전자공여능은 0.751 로양의상관관계를나타내었고 (P<0.05), 전자공여능 과 A 라디칼소거활성또한 0.930 의높은양의상관계 수를나타내었다 (P<0.01). 이는한약재의열처리시총폴 리페놀함량과항산화력간에 0.915(P<0.01) 의높은상관 관계를나타내었다는보고와같은결과를나타내었다 (29). 요 건조전처리와건조방법에따른대추의건조특성과품질의 변화를비교분석하였다. 수분함량은 glyceol 전처리에서 유의적으로낮았고열풍건조가천일및냉풍건조에비해건 조효율이높은것으로나타났다. 가밀도는 NaCl boiling 처 리에서가장높았고, 가용성고형분의함량의경우열풍건 조, 냉풍건조, 천일건조순으로높은함량을나타내었으며 전반적으로 glycerol 침지에서높은함량을보였다. 적정산 도는열풍건조가타건조방법에비해높은값을나타내었으 약 며, 전처리에따라서는무처리및 glycerol 침지에서높은 경향을나타내었다. 반면 boiling 처리시대추고유의산도 는저하되는것으로나타났다. 당산비의경우천일건조에서 가장높았으며다음으로냉풍건조열풍건조순으로나타났 고, 전처리에따라서는 NaCl boiling> glycerol> 무처리순 으로높은함량을나타내었다. 갈변도는열풍건조, 냉풍건 조, 천일건조순으로, 전처리방법에따라서는 NaCl boiling, 무처리, glycerol 침지순으로높은값을나타내었다. 적색 도의경우무처리가 NaCl boiling 및 glycerol 침지에비해 유의적으로높은경향을나타내었으며, boiling 처리한건조 대추의경우적색도는감소하고황색도는증가하는것으로 나타나기호성이다소저하되는것으로관찰되었다. 건조방 법에따른폴리페놀함량은열풍건조 > 냉풍건조 > 천일건조 순으로높은함량이검출되었으며, 전처리방법간에는무처 리및 glycerol 침지가 NaCl boiling 처리에비해유의적으 로높았다. 반면플라보노이드함량에서는 boiling 전처리를 행한모든건조방법에서높은함량이검출되었다. DPPH, A 라디칼소거활성은유용성분의함량과항산화활성 간의비례적인상관관계를나타내었으며, 열풍건조에서유 의적으로높은라디칼소거활성을나타내었다. 관능검사결 과 NaCl boiling 처리는외관과함께품질이가장떨어지는 것으로나타났으며, 종합적기호도는 glycerol 침지가가장 기호성이높은것으로조사되었고다음으로무처리, boiling 순이었다. 이상의결과종합적기호도및이화학적, 기능적 품질특성을고려해보았을때 glycerol 전처리와열풍건조 방법을효과적으로이용하는것이건조효율증대및품질손 상을억제할수있는방안이될것으로사료된다. REFERENCES 1. Abbas MF, Al-Niami JH, Al-Ani RF. 1998. Some physiological characteristics of fruits of jujube different stage of maturity. J Hort Sci 63: 337-339. 2. Lee HB. 1988. Studies on the change of chemical components of dried jujube (Zizyphus jujuba Miller) during storage. J Agric Sci 15: 95-113. 3. Na HS, Kim KS, Lee MY. 1996. Effect of jujube methanol extract on the hepatotoxicity in CCl 4 -treated rats. J Korean Soc Food Sci Nutr 25: 839-845. 4. Choi KS, Kwon KI, Lee JG, Lee RK. 2003. Studies on the chemical compositions and antitumor activities of jujube tea products. J Resource Development 22: 23-29. 5. Al-Reza SM, Yoon JI, Kim HJ, Kim JS, Kang SC. 2010. Anti-inflammatory activity of seed essential oil from Zizyphus jujuba. Food Chem Toxicol 48: 639-643. 6. Lee YG, Cho SY. 1995. Effect of jujube methanol extract on benzo(a)pyrene induced hepatotoxicity. J Korean Soc Food Nutr 24: 127-132. 7. Okamura N, Nohara T, Yagi A, Nishioka I. 1981. Studies on the constituents of Zizyphi fructus. III. Structures of dammarane-type saponins. Chem Pharm Bull 29: 676-683. 8. Lee DS, An DS. 1998. Effect of packaging conditions on keeping quality of fresh jujube. J Korean Food Sci Technol 30: 461-467.
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