J Korean Soc Food Sci Nutr 한국식품영양과학회지 45(12), 1799~1807(2016) http://dx.doi.org/10.3746/jkfn.2016.45.12.1799 유산균발효생두를이용한에스프레소커피의품질특성및항산화활성 김동호 연수지 장금일 충북대학교식품생명 축산과학부 Quality Characteristics and Antioxidant Activity of Espresso Coffee Prepared with Green Bean Fermented by Lactic Acid Bacteria DongHo Kim, SooJi Yeon, and KeumIl Jang Division of Food and Animal Sciences, Chungbuk National University ABSTRACT This study investigated the quality characteristics and antioxidant activities of espresso coffee prepared with green bean fermented by lactic acid bacteria. First, 10, 20, and 30% (w/v) green beans were fermented by Lactobacillus acidophilus KCTC 3145 at 37 C for 0, 12, and 24 h, respectively. Cells of L. acidophilus gradually increased with increasing green bean content and fermentation time. After drying fermented green beans, coffee powders were prepared by roasting (city level) and grinding (<75 mesh). Then, espresso coffee was extracted using coffee powder. The ph and chromaticity (L*, a*, and b* values) of espresso coffee decreased with fermentation time, whereas total acidity, total soluble solid contents, and brown color intensity increased. The ph level decreased with increasing contents of fermented green bean and total acidity increased. However, chromaticity, total soluble solid contents, and brown color intensity remained within a limited range. The antioxidant activities, including total polyphenol content, and DPPH and ABTS radical scavenging activities increased with increasing green bean content and fermentation time. Finally, sensory evaluation for taste, color, flavor, and overall preference revealed espresso coffee prepared with fermentation of 30% (w/v) green bean received the highest scores. Green bean fermented by lactic acid bacteria enhanced quality characteristics and antioxidant activities of espresso coffee, showing that lactic acid bacteria fermentation has potential use in the espresso coffee industry. Key words: espresso, coffee, lactic acid bacteria, quality, antioxidant 서 커피는꼭두서니과 (Rubiaceae) 코페아속 (Coffea) 에속하는쌍떡잎식물로 500속과 6,000여종이넘는커피나무에서수확한커피생두를가공한다음추출한음료로서 (1) 현재가장많이음용하고있는기호음료로알려져있다 (2). 커피생두는커피나무의열매의껍질을벗겨내면점액질로싸여있는씨앗으로정제하기위해건조및탈곡과정을거치게되는데, 건식법및습식법으로처리하면점액질을제거되면서커피생두를얻을수있다 (3). 커피생두에는생산지, 품종재배방법에따라약간의차이가나타나겠지만, 일반적으로 10~13% 의수분, 37~60% 의탄수화물, 9~18% 의지방질, 11~13% 의단백질, 3.0~4.5% 의무기질과생리활성물질등으로구성되어있다 (4). 커피의생리활성물질로는 catechins, anthocyanins 등의 flavonoids 성분, caffeic acid Received 12 August 2016; Accepted 25 October 2016 Corresponding author: KeumIl Jang, Division of Food and Animal Sciences, Chungbuk National University, Cheongju, Chungbuk 28644, Korea Email: jangki@chungbuk.ac.kr, Phone: +82432612569 론 및 ferulic acid 등이주된성분으로알려져있으며, trigonelline, quinolinic acid, pyrogallic acid, nicotinic acid, tannic acid 및 caffeine 등의성분도함유되어있다 (5). 그리고이들성분중 caffeine, chlorogenic acid, hydroxycinnamic acids 및 melanoidins 등은대표적항산화물질로서 (6) 만성질환의예방이나억제또는수명연장효능이있는것으로알려져있다 (7). 이러한생리활성물질을함유한커피의품질및기능성을향상시키기위하여다양한연구가진행되었는데, Kim과 Han(4) 은배전시간및추출용매에따라커피추출물의항산화효과가변화됨을보고하였고, Hwang 등 (8) 은추출시간후기에도더치커피추출액의페놀성분과항산화효과가유지되어추출된다고보고하였다. 또한, 커피생두분말을첨가한식빵의항산화특성연구 (9) 등커피의가공분야를넓히기위한연구가진행되고있지만대부분커피원두를이용한연구가대부분을차지하고있는실정이다. 커피생두를이용한연구로는커피의재배방법에따른커피생두의미세구조가변화 (10) 및커피생두품종에따른커피의향미특성 (11) 등재배방법및품종에대한연구가대부분으로커피생두가공에대한연구는부족한실정이다.
1800 김동호 연수지 장금일 최근에발효과정에의한생리활성작용이알려지면서발효식품이세계적으로건강기능성식품으로인식되고있고, 특히유산균은인간이이용할수있는매우유익한미생물로알려져있는데, probiotics로장내기능향상효과 (12,13) 가보고되면서오래전부터발효유제품을중심으로각종장류, 김치, 발효소시지, 의약품및가축의사료첨가제에이르기까지그특성에따라인류의생활에직 간접적으로밀접한관계를맺고있으며, 지금까지유산균은 300~400여종이알려져있다 (14). 또한, 유산균은발효식품에특유의풍미와우수한보존성을부여할뿐만아니라유당불내증의완화작용, 정장작용, 병원성세균의생육억제작용, 콜레스테롤저하작용, 항암작용, 항바이러스작용, 항스트레스작용등의다양한생리활성기능을나타내는것으로도알려지면서 (15 17), 콜레스테롤저하유산균을이용한요구르트제조 (18), 유산균발효를통한흑대추와일반건조대추추출물의항산화효과향상 (19) 및유산균발효를통한김치의기능성증진효과 (20) 등유산균발효를통한생리활성증진가능성에관한다양한연구가보고되고있다. 따라서본연구에서는커피생두를유산균으로발효한다음건조하여얻은유산균발효생두를제조하고, 이를로스팅및분쇄가공처리하여얻은커피분말로추출한유산균발효에스프레소커피의품질및항산화효과의변화를분석함으로써유산균발효를통한커피의품질및기능성효과향상을위한자료를제시하고자하였다. 재료및방법재료및유산균주유산균발효에스프레소커피제조를위한커피생두는 Megacoffee(BNC International, Gyeonggi, Korea) 에서 Brazil Santos NY2를구입하여통풍이잘되고서늘한곳에보관하면서사용하였다. 항산화활성을분석하기위한시약으로 gallic acid와 potassium persulfate, DPPH(2,2diphenyl1picrylhydrazyl), FolinCiocalteu's phenol reagent 및 ABTS[2,2'azinobis(3ethylbenzothiazoline 6sulfonic acid)] 는 SigmaAldrich Co.(St. Louis, MD, USA) 에서구입하여사용하였다. 그리고 Na 2CO 3(sodium carbonate) 용액은 Samchun Pure Chemical Co.(Seoul, Korea) 에서구입하였으며, Lascorbic acid는 Junsei Chemical Co.(Tokyo, Japan) 에서구입하여사용하였다. Lactobacillus acidophilus KCTC 3145는한국미생물자원센터 (Korean Collection for Type Cultures, KCTC, Daejeon, Korea) 에서분양받았으며, 유산균배양을위한배지로는 MRS 배지 (Lactobacilli MRS broth, Difco Co., Detroit, MI, USA) 를사용하였다. 유산균을이용한커피생두의발효및유산균수커피생두를유산균으로발효시키기위한커피생두배지 는 100 C의증류수에서 3분간살균시킨생두를 0.85%(w/ v) 생리식염수에 10, 20, 30%(w/v) 로첨가하여제조하였으며, 커피생두발효를위한유산균으로는건강기능식품공전에제시된프로바이오틱유산균 (12) 으로잘알려진 Lactobacillus acidophilus KCTC 3145를분양받아사용하였다. 먼저 Lactobacillus acidophilus KCTC 3145 유산균을 MRS 배지에접종하고 37 C에서 24시간배양시킨다음배양액 1 ml를취하고원심분리 (6,067 g, VS15000 CFN, Vision, Bucheon, Korea) 하여 MRS 배지성분을제거하고, 제조된각각의커피생두배지액 1 ml로다시현탁시켜준비하였다. 그리고생두함량별로제조한커피생두배지에준비된유산균을최종 1%(v/v) 로접종하고 shaking incubator(si 600R, JEIO Tech, Daejeon, Korea) 에서 100 rpm으로 37 C에서 24시간동안커피생두를발효시켰다. 그리고동일한조건으로준비한 10, 20, 30%(w/v) 커피생두배지에유산균을접종하지않고 0, 12, 24시간동안유지한생두를비발효커피 (control) 로각각사용하였다. 발효기간중변화되는유산균수는 0, 12, 24시간마다각각의발효액에서 1 ml를취하여십진희석한다음 MRS 한천배지를이용하여 pour plate method로 37 C에서 24시간배양시킨후유산균수를 colony forming units(cfu/ml) 로나타내었다. 그리고커피생두함량별배지에서비발효및발효된생두를꺼내어건조기 (MRCB, Mirae Science, Anyang, Korea) 로옮긴다음 25 C에서 3시간동안풍건시켜에스프레소커피제조에사용하였다. 유산균발효생두를이용한에스프레소커피의제조유산균발효생두를이용한에스프레소커피를제조하기위해서먼저커피생두함량별로유산균발효하고건조된각각의발효커피생두를열풍로스터 (CR100, Imax, Seoul, Korea) 를이용하여시티 (city) 단계로로스팅한다음그라인더 (Bistro, Bodum, Pyrmont, Australia) 로분말화시키고 75 mesh 체로사별하여유산균발효커피원두분말을제조하였다. 그리고제조된발효커피원두분말을에스프레소추출기 (HD8323, Philips & Saeco, Shenzhen, China) 로 15초동안 30 ml씩각각추출하여에스프레소커피를제조하였다. 그리고생두첨가량별로제조된배지에서유산균을접종하지않은생두로제조한에스프레소커피를대조구 (control) 로사용하였다. 에스프레소커피의 ph와가용성고형분함량및총산도측정에스프레소커피의 ph와가용성고형분함량은각각 ph meter(docuph meter, Sartorius, Bohemia, New York, NY, USA) 와굴절당도계 (Master1M, Atago Co., Ltd., Tokyo, Japan) 로 3회반복측정하여평균값을사용하였다. 그리고에스프레소커피의총산도는커피 10 ml에증류수를가하여 100 ml로정용한후 0.1 N NaOH를가하여 ph
유산균발효생두커피의품질및항산화활성 1801 8.3이될때까지적정한후소요된 NaOH의 ml를 lactic acid로환산하였다 (21). 에스프레소커피의갈색도및색도측정에스프레소커피의갈색도는 Bravo 등 (22) 의방법을응용하여추출된커피시료를 3차증류수로 40배희석하여 420 nm에서분광광도계 (UV1800, Shimadzu, Tokyo, Japan) 를이용하여흡광도를 3회반복측정하였다. 에스프레소커피의색도는추출된커피 10 ml를 petri dish에담아고정시킨후색차계 (CR300, Minolta, Osaka, Japan) 를사용하여 Hunter L값 ( 명도 ), a값 ( 적색도 ), b값 ( 황색도 ) 과색차값 (color difference, ΔE) 을측정하였다 (23). 모든시료에대하여 3 회반복측정하였으며, 사용된표준색판은백색판 (L=93.50, a=0.31, b=0.32) 을사용하였다. 에스프레소커피의총폴리페놀함량에스프레소커피의총폴리페놀함량은 Dewanto 등 (24) 의방법에따라 FolinCiocalteu reagent가시료의폴리페놀성화합물에의해환원된결과, 몰리브덴청색으로발색하는것을원리로측정하였다. 커피추출액 100 μl에 2% Na 2CO 3 용액 (w/v) 2 ml를첨가한후 3분간실온에서방치하였다. 그리고 50% FolinCiocalteu reagent를 0.1 ml 가한후 30분동안반응시키고흡광도값을 750 nm에서측정하였다. 표준물질로 gallic acid를사용하여검량선을작성한후총폴리페놀함량은시료 1 ml당 mg garlic acid equivalent(gae) 로나타내었다. 그리고모든시료에대하여 3회반복측정하였다. 에스프레소커피의 DPPH 라디칼소거능에스프레소커피의 DPPH 자유라디칼소거능은 Blois (25) 의방법을이용하여분석하였다. 먼저 DPPH 용액을 0.005 g/100 ml로 99.9% 에탄올에희석한후 2시간이상암소방치하고, 520 nm에서흡광도값을 1.5~1.7로보정하여준비하였다. 에스프레소커피시료 0.2 ml에 DPPH 용액 0.8 ml를넣고 30분간실온에반응시킨후 520 nm에서흡광도를측정하였으며, 표준물질로 Lascorbic acid를동량첨가하였다. DPPH 라디칼소거능은정량적으로비교분석하기위하여 ascorbic acid에해당하는항산화력 (AEAC, Lascorbic acid equivalent antioxidant capacity, mg AE/ ml) 으로나타내었으며, 모든시료는 3회반복측정하였다. 에스프레소커피의 ABTS 라디칼소거능에스프레소커피의 ABTS 라디칼소거능은 Ahn 등 (26) 의방법에의하여 ABTS cation decolorization assay를수행하였다. 7.4 mm의 ABTS와 2.6 mm의 potassium phosphate를 1:1로동량혼합한후암실에서 12~16시간교반하여반응시키고, 735 nm에서흡광도값이 1.4~1.5가되도록몰흡광계수 (ε=3.6 10 4 M 1 cm 1 ) 를이용하여증류수로희 석하였다. 각각의에스프레소커피시료 50 μl를희석된 ABTS 용액 1 ml에가하여 60분간반응시키고 735 nm에서흡광도를측정하였으며, 표준물질로 Lascorbic acid를동량첨가하였다. ABTS 라디칼소거능은 ascorbic acid에해당하는항산화력 (AEAC, Lascorbic acid equivalent antioxidant capacity, mg AE/mL) 으로나타내었으며, 모든시료에대하여 3회반복측정하였다. 에스프레소커피의관능검사유산균발효에스프레소커피의관능평가는충북대학교식품생명공학과남녀대학생및대학원생 30명을대상으로관능검사의목적, 방법및동일한커피를구분하는등의기본적인관능패널교육을거친다음 7점척도법으로평가하였다. 먼저미발효생두로제조한에스프레소커피 (R) 와유산균발효에스프레소커피 30 ml를에스프레소잔에담아상호비교평가하였으며, 평가항목으로는색 (color), 맛 (taste), 향 (flavor) 및전체적인기호도 (overall preference) 를측정하였다. 시료의비교는미발효생두로제조한에스프레소커피 (R) 를비교대상으로하여 R보다매우좋다 (7점), 약간좋다 (6점), 좋다 (5점), R과같다 (4점), R보다나쁘다 (3점), 약간나쁘다 (2점), 매우나쁘다 (1점) 으로구분하여평가하도록하였다 (27). 통계처리통계처리는 SAS(Statistical Analysis System, Ver. 8.01, SAS Institute Inc., Cary, NC, USA) program을이용하여각측정군의평균과표준편차를산출하고처리간의차이유무를 oneway ANOVA(analysis of variation) 로분석한후 Duncan's multiple range test를이용하여유의성을검정하였다. 결과및고찰유산균발효를통한커피생두배지에서유산균수의변화 10, 20, 30%(w/v) 커피생두가함유된커피생두배지에 Lactobacillus acidophilus KCTC 3145를접종한다음 37 C에서 24시간발효시키는동안 Lactobacillus acidophilus KCTC 3145의균수변화를 Fig. 1에나타내었다. 먼저 Lactobacillus acidophilus KCTC 3145의균수는발효시간이증가할수록커피생두함량에관계없이모두 5.82~ 5.86 log CFU/mL에서 6.42~6.44 log CFU/mL로완만히증가하는경향을나타내었다. 이는유산균생육영양원이적은자작나무수액에서유산균발효를유산균의생육이완만하게증가하였다고보고한 Kim 등 (14) 의보고를미루어볼때커피생두배지에유산균이생육에필요한당이적기때문에발효중 Lactobacillus acidophilus KCTC 3145 유산균수가완만하게증가한것으로생각된다.
1802 김동호 연수지 장금일 Lactobacillus acidophilus. (log CFU/mL). 6.5 6.0 5.5 0 6 12 18 24 Fermentation time (h) Fig. 1. Cell growth of Lactobacillus acidophilus KCTC 3145 on various green bean solutions during fermentation for 24 h at 37 C., 10% (w/v) green bean., 20% (w/v) green bean., 30% (w/v) green bean. Values are mean±sd. 발효생두를이용한에스프레소커피의 ph, 총산도, 가용성고형분함량및갈색도 Lactobacillus acidophilus KCTC 3145로발효시킨발효생두를이용하여제조한에스프레소커피의 ph, 산도, 가용성고형분함량및갈색도를비교한결과를 Table 1에나타내었다. 먼저발효시간이길어질수록에스프레소커피의 ph는모두 0시간발효커피 (ph 5.63~5.70) 및 24시간비발효커피 (ph 5.62~5.65) 에비하여 24시간발효후 ph 5.16~5.26으로낮아지는경향을나타내었으며 (P<0.05), 특히 30%(w/v) 생두를발효시킨에스프레소커피 () 및 20%(w/v) 생두를발효시킨에스프레소커피 () 에서는 24시간동안발효되면서각각 ph 5.16 및 5.19를나타내어 10%(w/v) 생두를발효시킨에스프레소커피 () 보다낮은값을나타내었다. 그리고발효생두에스프레소 Table 1. Changes of ph, total acidity, total soluble solid content, and brown color intensity of espresso coffee prepared with green bean fermented for 24 h at 37 C using Lactobacillus acidophilus KCTC 3145 ph Total acidity (%) Total soluble solid contents ( Brix) Brown color intensity (420 nm) Samples Fermentation time (h) 0 12 24 5.70±0.01 a 5.67±0.01 5.67±0.02 5.65±0.07 a 5.63±0.11 a 5.63±0.12 a 5.64±0.02 Ab 5.64±0.03 A 5.64±0.02 A 5.40±0.04 Bb 5.37±0.03 BCb 5.33±0.03 Cb 5.62±0.02 Ab 5.65±0.03 A 5.65±0.02 A 5.26±0.04 Bc 5.19±0.02 Cc 5.16±0.04 Cc Fvalue 9.96 * 0.92 3.65 42.55 *** 34.90 *** 29.13 *** Fvalue 0.41 76.62 *** 195.87 *** 0.23±0.12 0.27±0.12 0.27±0.21 0.20±0.10 b 0.19±0.08 c 0.23±0.06 c 0.23±0.06 B 0.20±0.10 B 0.17±0.06 B 0.40±0.10 Ab 0.45±0.05 Ab 0.47±0.12 Ab 0.27±0.12 C 0.27±0.06 C 0.30±0.10 C 0.87±0.15 Ba 0.97±0.12 Ba 1.23±0.15 Aa 0.11 0.50 0.76 24.31 ** 63.55 *** 61.58 *** Fvalue 0.21 7.64 *** 37.55 *** 5.7±0.58 5.0±1.00 C 5.7±0.58 B 0.80 5.3±0.58 5.2±0.76 C 5.7±0.58 B 0.47 5.3±0.58 5.3±0.58 BC 5.7±0.58 B 0.33 5.3±0.58 b 6.7±0.58 Aa 7.3±0.58 Aa 9.33 * 5.8±0.29 b 6.5±0.50 ABb 7.7±0.29 Aa 18.60 ** 5.7±0.76 b 6.7±0.58 Aab 7.7±0.58 Aa 7.20 * Fvalue 0.44 4.07 * 11.16 *** 0.270±0.002 0.273±0.002 B 0.274±0.002 B 3.23 0.274±0.004 0.273±0.001 B 0.276±0.002 B 0.53 0.273±0.002 0.274±0.004 B 0.274±0.005 B 0.13 0.273±0.002 b 0.285±0.002 Aa 0.286±0.003 Aa 23.69 ** 0.274±0.004 b 0.286±0.007 Aab 0.289±0.007 Aa 4.99 * 0.274±0.005 b 0.286±0.003 Aa 0.290±0.005 Aa 11.56 ** Fvalue 0.51 9.28 *** 8.62 ** : control espresso coffee prepared with 10% (w/v) green bean. : control espresso coffee prepared with 20% (w/v) green bean. : control espresso coffee prepared with 30% (w/v) green bean. : espresso coffee prepared with fermentation of 10% (w/v) green bean. : espresso coffee prepared with fermentation of 20% (w/v) green bean. : espresso coffee prepared with fermentation of 30% (w/v) green bean. Values are mean±sd. Different letters in the same column (A,B) and row (ac) are significantly different at P<0.05. Significant at * P<0.05, ** P<0.01, and *** P<0.001, respectively.
유산균발효생두커피의품질및항산화활성 1803 커피의산도는 0시간발효커피의 0.19~0.27% 와 24시간비발효커피의 0.27~0.30% 에서 24시간동안발효시킨생두를이용한경우 0.87~1.23% 까지급격히증가하는경향을나타내었으며 (P<0.05), 특히 은 및 EFB 20보다높은산도를나타내었다. 일반적으로유산균이발효되는과정에서 ph가감소하며산도가증가하는것은유산균에의해커피생두가일부발효되면서생성되는젖산, 아세트산, 포름산및일부커피주요유기산등산성물질들의증가에의한것으로보고되어있다 (23,2830). 또한, 커피생두는로스팅공정을거치면서 citric acid, malic acid는감소하고 acetic acid는증가하면서 lactic acid와 formic acid가생성되었다는 Park 등 (31) 의보고와비교해볼때 이다른에스프레소커피보다유산균발효및로스팅과정에서생성된유기산의함량이높아져서에스프레소커피의 ph가낮아지고총산도가높아진것으로생각된다. 발효생두를이용하여제조한에스프레소커피의가용성고형분함량과갈색도 (Table 1) 는발효시간이길어질수록각각 5.3~5.8 Brix에서 7.3~7.7 Brix, 0.273~0.274에서 0.286~0.290으로유의적으로증가하였으나 (P<0.05), 갈색도는변화정도가미비하게증가하였다. 이와같은결과는로스팅공정중섬유질은분해되어캐러멜당을생성하나미분쇄된섬유질은추출콜로이드를생성하여추출커피의중후함 (body) 을증가시킨다는 Yoon과 Choi(32) 의보고와비교해볼때발효시간이길어질수록유산균발효에의해일부소모된당에비해로스팅공정중에동일중량의원두에상대적으로남아있는섬유질함량비율의증가로가용성고형분함량이증가한것으로생각한다. 그리고커피의갈색도는일반적으로로스팅과정에서갈색물질이생성되기때문인데, 커피의갈색물질은 sucrose의 caramelization 반응및 amino components와환원당사이에서의 maillard 반응과정을통해생성되는물질, chlorogenic acid 및분해산물그리고 trigonelline과의복합적인반응에의해생성된다는 Macrae(33) 의보고를미루어볼때, 생두를유산균발효시킨커피의갈색도증가는커피생두가유산균발효를거치면서생성되는커피성분의분해산물및발효산물에의해갈색물질의생성이유도되었기때문으로생각된다. 발효생두를이용한에스프레소커피의색도생두의함량및유산균발효시간에따른발효생두를이용한에스프레소커피의색도비교는 Table 2에나타내었다. 먼저 의 Hunter L값 ( 명도 ), a값 ( 적색도 ) 및 b값 ( 황색도 ) 에서는 0시간발효커피의 39.58, 1.24, 1.98과 24시간비발효커피의 39.82, 1.21, 1.95에비하여 24시간발효시키고제조한커피에서는각각 34.36, 0.95, 1.10을나타내어모두유의적으로감소하는경향을나타내었으나 (P<0.05), 생두함량별에따른차이는미비하였다. 그리고색차값은미국 National Bureau of Standards의규정 (34) 에서제시된색차값에따른색변화정도 (trace, 0.0~0.5; slight, 0.5 ~1.5; noticeable, 1.5~3.0; appreciable, 3.0~6.0; much, 6.0~12.0; very much, >12.0) 를미루어볼때, 에서 12시간발효후 3.69를나타내었고, 24시간발효후에는 5.20을나타내어모두다소의차이 (appreciable) 단계를보였지만관능적구별은어려울것으로판단된다. 이와같은결과는커피가공방법의차이에따라커피의색도가영향을받을수있다고보고한 Mendes 등 (35) 의보고와비교해볼때, 발효및로스팅과정중일부생성된가용성고형분및갈색물질들의영향으로명도 (Lvalue) 와황색도 (bvalue) 가감소된것으로생각된다. 발효생두를이용한에스프레소커피의총폴리페놀함량및항산화활성생두의함량및유산균발효시간에따른발효생두를이용한에스프레소커피의총폴리페놀함량은 0시간발효커피의 3.73~3.76과 24시간비발효커피의 3.68~3.70에서 24 시간발효후 6.24~6.30 mg GAE/mL의범위로유의적인증가를나타내었으며 (Table 3), 특히 에서는 12시간발효시킨에스프레소커피 (6.21 mg GAE/mL) 의총폴리페놀함량이 0시간발효커피 (3.76 mg GAE/mL) 보다급격하게증가하였다 (P<0.05). 이는진균류균사체로발효시킨커피생두의총폴리페놀함량이증가하였다는 Shin 등 (36) 의보고와대추추출물과율피추출물의유산균발효에서각각총폴리페놀함량이증가하였다는 Jeong 등 (37) 과 Choi 등 (38) 의보고를미루어볼때생두의유산균발효에의해총폴리페놀함량이증가한것으로생각한다. 발효생두를이용한에스프레소커피의 DPPH 및 ABTS 라디칼소거능의변화를 Table 3에나타내었다. DPPH 및 ABTS 라디칼소거능모두발효시간이증가할수록유의적으로증가하는경향을나타내었고 (P<0.05), 발효생두함량이높을수록 ABTS 라디칼소거능이증가하였다 (P<0.05). 특히 에서 ABTS 라디칼소거능은 25.7 mg AEAC/ ml로가장높은값을나타내었다. 이는버섯추출물및흑마늘의유산균발효과정에서각각 DPPH 라디칼소거능이증가되었고 (39,40), 버섯발효유제조시유산균발효에의해 ABTS 라디칼소거능이증가하였다고보고 (41) 와유사한경향을나타내었다. 배당체형태의항산화활성성분들은당쇄분해효소 (glycoside hydrolase) 에의해당이제거될경우보다높은항산화활성을나타내며 (42), Leuconostoc 속균주로부터당쇄분해효소또는생물전환계에의해베리또는과채류주스의항산화활성이약 16~40% 정도향상된다고보고되었다 (43). 또한, 발효과정을통하여새롭게생성되는유효성분과유산균이생성하는 2차대사산물이항산화관련효소에긍정적으로작용한다고보고되었다 (19,44,45). 따라서본연구에서도커피생두에대한유산균발효특성으로인하여항산화성분과활성이증진되었을것으로생각된다. 그러나유산균발효에의한커피생두의생리활성및항산화성분
1804 김동호 연수지 장금일 Table 2. Changes of Hunter s color L, a, b, and ΔE value of espresso coffee prepared with green bean fermented for 24 h at 37 C using Lactobacillus acidophilus KCTC 3145 Hunter s Fermentation time (h) Samples Fvalue color value 0 12 24 L* a* b* ΔE 39.87±0.21 39.63±0.17 39.48±0.21 39.71±0.84 a 39.64±0.36 a 39.58±0.29 a 39.65±0.09 A 39.79±0.25 A 39.76±0.11 A 36.08±0.68 Bb 36.01±0.69 Bb 35.86±0.80 Bb 39.79±0.17 A 39.76±0.20 A 39.82±0.25 A 34.65±0.08 Bc 34.56±0.72 Bc 34.36±0.82 Bc Fvalue 0.29 45.94 *** 113.05 *** 1.24±0.04 1.25±0.03 1.26±0.04 1.21±0.11 a 1.22±0.08 a 1.24±0.08 a 1.25±0.03 A 1.21±0.06 A 1.20±0.12 A 1.02±0.09 Bb 1.00±0.02 Bb 0.98±0.03 Bb 1.22±0.04 A 1.20±0.07 A 1.21±0.09 A 1.00±0.04 Bb 0.97±0.05 Bb 0.95±0.05 Bb Fvalue 0.26 9.76 *** 15.63 *** 1.96±0.11 1.97±0.24 1.98±0.24 1.95±0.11 a 1.96±0.07 a 1.98±0.07 a 1.96±0.13 A 1.96±0.04 A 1.98±0.16 A 1.37±0.11 Bb 1.33±0.09 Bb 1.30±0.18 Bb 1.93±0.20 A 1.94±0.18 A 1.95±0.28 A 1.19±0.03 Bc 1.13±0.11 Bc 1.10±0.12 Bb Fvalue 0.02 23.75 *** 19.39 *** 0.16 0.03 0.10 0.22 0.17 0.29 3.84 3.68 3.69 Samples are the same as Table 1. Values are mean±sd. Different letters in the same column (A,B) and row (ac) are significantly different at P<0.05. Significant at * P<0.05, ** P<0.01 and *** P<0.001, respectively. 0.09 0.14 0.34 5.28 5.15 5.20 11.30 0.45 2.43 52.77 *** 54.69 *** 46.59 *** 0.83 0.70 0.44 5.65 * 19.13 ** 23.44 ** 0.05 0.03 0.02 62.94 *** 67.29 *** 37.91 *** 규명을위해서는활성성분의정제및구조등의추가적인연구가필요한것으로판단된다. 발효생두를이용한에스프레소커피의관능검사발효생두를이용하여제조한에스프레소커피의관능검사는미발효생두를이용하여제조한에스프레소커피 (R) 와비교하여 R보다매우나쁘다 (1점) 부터 R과같다 (4점) 및 R 보다매우좋다 (7점) 까지 7점척도법으로맛, 색, 향및전체적인선호도분석을하여 Table 4에나타내었다. 먼저발효생두를이용하여제조한에스프레소커피가모두 R보다맛에서기호도가낮게나타났는데, 이는유산균발효에의해생성되는유기산에의해신맛이조금증가하였기때문으로생각된다. 반면 의경우에스프레소커피의색과향에서 R보다선호도가높게나타났는데, 이는 에서유산균발효에의해다른에스프레소커피보다높아진커피의갈색도및갈색성분의영향 (33) 때문으로생각된다. 그리고발효생두를이용하여제조한에스프레소커피간의맛, 색및향의경우 이 및 보다높은선호 도를나타내었으며 (P<0.01), 전체적인기호도는 > 순으로나타나종합적으로 이미발효생두로제조한에스프레소커피와다른에스프레소커피처리구보다유의적으로높은선호도를나타내었다. 이는자작나무수액에 Lactobacillus 속유산균발효액이다른유산균발효액보다관능적기호도가우수하다는보고 (14) 와유사한경향을나타내었다. 따라서커피의유산균발효에의해기존에스프레소커피보다색과향이향상되면서항산화활성이증가한에스프레소커피의제조가가능함을확인할수있었다. 결론적으로유산균발효를시킨발효생두를이용한에스프레소커피의제조가가능하였는데, 일반커피에비하여유산균발효시간과발효를위한생두함량이증가할수록 ph가낮아지면서총산도, 가용성고형분함량과갈색도는증가하였다. 또한, 유산균발효에의해에스프레소커피의항산화효과가증가하는경향을나타내었다. 관능적인면에서 이가장높은선호도를나타내었다. 따라서본연구에서는일반에스프레소커피와유산균발효생두를이용
유산균발효생두커피의품질및항산화활성 1805 Table 3. Changes of antioxidant activities of espresso coffee prepared with green bean fermented for 24 h at 37 C using Lactobacillus acidophilus KCTC 3145 Total polyphenol content (mg GAE/mL) Samples Fermentation time (h) 0 12 24 3.67±0.15 3.64±0.08 3.69±0.16 3.73±0.18 b 3.75±0.08 b 3.76±0.12 b 3.69±0.08 B 3.69±0.07 B 3.68±0.07 B 6.17±0.06 Aa 6.20±0.05 Aa 6.21±0.05 Aa 3.68±0.04 B 3.70±0.04 B 3.68±0.12 B 6.24±0.05 Aa 6.27±0.05 Aa 6.30±0.05 Aa Fvalue 0.01 0.58 0.01 461.54 *** 1,805.33 *** 1,079.26 *** Fvalue 0.36 1,438.40 *** 1,500.61 *** DPPH radical scavenging activity (mg AE/mL) 34.9±0.7 35.2±0.1 35.2±0.4 b 35.2±0.1 c 35.2±0.6 c 35.9±0.8 c 35.2±1.1 C 34.9±1.6 C 35.4±0.5 Cb 40.1±0.6 Bb 40.2±1.9 Bb 42.9±1.4 Ab 36.8±0.9 B 36.8±0.9 B 36.8±0.9 Ba 44.6±1.5 Aa 44.5±1.7 Aa 46.3±1.2 Aa 3.96 3.00 6.55 * 72.08 *** 28.72 *** 65.98 *** Fvalue 1.07 21.52 *** 42.91 *** ABTS radical scavenging activity (mg AE/mL) 19.8±0.2 B 19.8±0.2 B 20.0±0.6 B 19.8±0.1 Bc 20.1±0.5 Bc 20.9±0.4 Ac 19.9±0.2 C 19.9±0.3 C 19.9±0.4 C 21.6±1.1 Bb 22.7±1.4 ABb 23.7±1.0 Ab 19.9±0.3 C 20.0±0.3 C 20.0±0.5 C 23.5±0.4 Ba 25.1±1.0 Aa 25.7±0.4 Aa 0.32 0.54 0.05 24.07 ** 17.15 ** 41.03 *** Fvalue 3.99 * 11.15 *** 77.31 *** Samples are the same as Table 1. Values are mean±sd. Different letters in the same column (A,B) and row (ac) are significantly different at P<0.05. Significant at * P<0.05, ** P<0.01, and *** P<0.001, respectively. Table 4. Sensory test profiles for espresso coffee prepared with green bean fermented for 24 h at 37 C using Lactobacillus acidophilus KCTC 3145 Samples Taste Color Flavor Fvalue 3.20±1.00 b 3.27±0.58 b 3.80±0.81 a 4.91 ** 3.43±2.28 b 3.30±2.09 b 5.07±2.29 a 5.88 ** 3.67±2.22 b 4.10±2.52 b 5.43±1.79 a 5.26 ** Overall preference 3.43±0.94 b 3.37±0.76 b 4.23±1.17 a 7.43 *** Samples are the same as Table 1. Values are mean±sd. Different letters in the same column (ac) are significantly different at P<0.05. Significant at ** P<0.01 and *** P<0.001, respectively. 하여제조한에스프레소커피의품질및항산화특성을상호비교하고관능적특성을확인함으로써커피생두의유산균발효를통해품질및생리활성이향상된에스프레소커피생산을위한자료를제시하였다고생각된다. 요 본연구에서는유산균으로발효시킨발효생두를이용하여제조한에스프레소커피의품질및항산화효과를분석하였 약 다. 먼저 Lactobacillus acidophilus KCTC 3145를이용하여 10, 20, 30%(w/v) 함량의커피생두를 37 C에서 0, 12, 24시간동안발효시켰다. 그리고발효된커피생두를건조한다음로스팅및분쇄하여얻은커피분말로에스프레소커피를제조하여 ph, 산도, 가용성고형분함량, 갈색도, 색도, 항산화활성및관능검사를비교분석하였다. 발효중유산균수의변화는발효를위한생두의함량과유산균발효시간이증가할수록전체적으로완만히증가하는경향을나타내었다. 발효시간이증가할수록발효생두를이용한에스프레소커피의 ph 및색도 (L*, a*, b* 값 ) 는감소했지만, 총산도, 가용성고형분함량및갈색도는증가하는경향을나타내었다. 발효생두의함량이증가할수록에스프레소커피의 ph는감소한반면총산도는증가하였고, 색도, 가용성고형분함량및갈색도는유사하게나타났다. 그리고항산화효과에서는발효시간및발효생두의함량이증가할수록총폴리페놀함량과 DPPH 및 ABTS 라디칼소거능은모두증가하였으며, 관능특성으로맛, 색, 향및전체적인기호도에서 이가장높은선호도를나타내었다. 따라서본연구에서는유산균발효생두를이용하여제조한에스프레소커피의품질및항산화특성을상호비교하고관능적특성을확인함으로써유산균발효를통한에스프레소커피의품질및기능성효과향상가능성에대한자료를제시하였다고
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