KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY Vl. 17, N. 33~37 (011) q t s ü CO d w ½y» 1 Á 1 Áx Á 1, 1 ûw tw mœw Cntrl f Micrbial Shelf Life f Perishable Fd by Real-Time Mnitring f CO Cncentratin f its Package Hwan Ki Kim 1, Duck Sn An 1, Hyuk Jae Lee and Dng Sun Lee 1, 1 Department f Fd Science and Bitechnlgy Department f Infrmatin and Cmmunicatin Engineering, Kyungnam University, Changwn, 631-701 Krea "CTUSBDU Real time cntrl lgic f micrbial shelf life f a perishable fd, seasned prk meat has been frmulated which explits mnitring f CO cncentratin f the package. The ptential f the prpsed lgic was examined fr strage at dynamic temperature cnditins. The start f increase in CO prductin rate frm the fd r rate f package CO cncentratin change was fund t cincide with the pint f micrbial quality limit and culd be used as an index f micrbial shelf life determinatin. This als crrespnded t lag time f CO cncentratin change r time fr the CO cncentratin t reach a certain value. The applicatin ptential f the prpsed lgic was cnfirmed fr a sensr system t measure n real time and transmit the CO cncentratin wireless t the cmputer system.,fzxpset Micrbial spilage, Shelf life, Package atmsphere, Real time mnitring, Carbn dixide y y ù š ù t ƒœs þ mš. t ù w r ƒ, q» p ƒ. þt ƒ ƒ, þ m qƒ w. wš, ƒ w xš. w t w m ƒ ƒ w. Crrespnding Authr : Dng Sun Lee Department f Fd Science and Bitechnlgy, Kyungnam University, 449 Wryeng-dng, Changwn, 631-701 Krea E-mail : <dngsun@kyungnam.ac.kr> q þt qƒ tš, dù d w 1,). w dwù dw š y ƒ». w ty y w w, y w ƒ wù t dw. w w» w, w t ty d w wš w ƒ. wù y», m w w (time-temperature indicatr, TTI) 3). q j w my» s w š, w fw, þt ty yw w
34 ½y»ÁÁxÁ w swz TTI. TTIƒ w t ty txw w TTI wš œw. š TTI y s y t t w» t t ƒ wù w. t»w w wù q s headspace w 4). wì s ü { ù» y ùkü wù q dw w ƒ ƒw. {» wù CO q wì sü, q š 5-7). w CO s» y p qw, y ty d w ƒ. t q þt wù š» w s CO y dw sensr l wš, w ƒ mw. 1. š» Ready-t-ck xk š» 1 kg š» 34 g (Chengjengwn, Chenan, Krea) y w 6 C w w. š» 1,000 ml ( 7.5 cm, 16.5 cm) wš screw cap w.. CO d sensr l q t s CO dw sensr l w» w ƒ ƒw sensr mw Table 1 8,9). Fiber ptic sensr s ew» w rw x š w yƒ 10). š y š CO d š þt s». s ü ew CO yw (nndispersive infrared, NDIR) ƒ w q. x dƒ 0,000 ppm(%)ü þ q t w w ƒ. Ÿw x w NDIR dƒ K33(SenseAir, Delsb, Sweden)ƒ d ƒ w ùkù w. K33 RFID tag w m ts w prttype d l Fig. 1 w. s ü RFID tag CO y dw l wš w l w. K33 sensr mw d l y ¼» w( 1km), UART x RS485 y RS485 cnverter z w yw. š main chipset MCU (ARM 3bit 7MHz) m l ww. w l w ZigBee (Xbee Pr 1km m,.4 GHz, 38400 bps) mw l w. d» ZigBee mdule w w Table 1. Types f CO sensrs t be ptentially used fr fd packaging Type Sensing principle Advantages Disadvantages Cmmercial examples Nndispersive infrared detectr (NDIR) Fiber ptics Metal xide Energy absrptin f CO in infrared wavelength Changes in ptical prperties f film layer at the tip f a fiber respnding t CO Cnductance r resistance change due t chemical reactins n the sensr surface Summarized frm Neethirajan et al. 8) and Krtcenkv 9). Simple in structure and easy t use Chemically inert and resistant t the presence f ther gases Rbustness and lngterm stability Bulky and expensive Use f lenses Ptential irreversible binding f metal xides with sulfur cmpunds frm fds Carbcap f Vaisala (Finland); Bta f Vernier (USA); K33 f Sense- Air (Sweden) CDM series f Figar (Japan)
CO 농도의 측정에 의한 미생물적 저장수명 제어 Vl. 17, N. (011) Fig. 1. 35 Diagram f wireless CO cncentratin measurement system n real time basis. 이터를 받아 MCU에 데이터를 저장한다. 저장된 데이터는 LAN 망으로 UDP 프로토콜에 의하여 cmputer로 전송된 다. Fig. 에서는 제작된 실시간 CO 농도 측정통신 시스템 을 보여주고 있다. 3개의 sensr 결합 mdule을 제작하였 고, 측정된 CO 농도와 온도 데이터는 무선으로 실시간으 로 전달되어 노트북 cmputer의 hard disk에 저장되게 제 작되었다. 필요에 따라서 온도 데이터는 별도의 sensr에 측정되어 lgging 되기도 하였다. 필요 시 제작된 CO 농도 측정 sensr 시스템의 유효성을 확인하기 위하여 기체크로마토그래피에 의한 CO 농도 측 정을 병행하였다. 이를 위해 포장내부기체 1 ml를 취하여 Alltech CTR I 분리관(clumn)과 열전도도 검출기(TCD, thermal cnductivity detectr)가 장착된 기체크로마토그래 프(Mdel 3800, Varian Inc., Pal Alt, CA, USA)로 주 입하였다. 측정조건으로서 운반기체(carrier gas)는 He을 30 ml/min의 유량으로 흐르게 하였고, 오븐온도는 50 C, 주 입부(injectin prt) 온도는 80 C, 검출기(detectr) 온도는 95 C를 유지하였다. 미생물적 품질 측정 미생물적 품질로서는 호기적 총균수를 측정하였다. 시료 30 g을 stmacher bag에 채취하여 멸균된 0.5% 펩톤수 90 ml를 첨가하고 Stmacher (Stmacher 400 circulatr, Seward Limited, The UK)를 이용하여 300 rpm에서 4분 동안 균질화하여 시료 원액으로 이용하였으며, 시료 원액을 단계별로 10배씩 희석하여 Plate Cunt Agar (PCA; Difc Labratries, Detrit, USA) 배지에 주입평판하여 30 C에 서 3일간 배양하여 콜로니형성단위(clny frming unit, CFU)를 계수하였다. 3. 결과 및 고찰 온도조건에 따른 포장 농도변화의 거동분석 먼저 저장수명을 결정하는 주요 인자로서 온도조건에 따 른 미생물 성장과 CO 농도변화특성을분석하였다. 이전의 연구에서 변패성 포장에서의 CO 농도변화의 유도기가 미 생물적 품질한계에 해당되므로 이가 저장수명을 결정할 수 있는 하나의 기준으로 확인된 바 있다. 하지만 이는 일정 온도조건에서는 쉽게 적용될 수 있으나, 실시간적으로 다양 1. CO Phtgraph f wireless CO sensing system fr perishable fd packages. Fig.. 5)
36 ½y»ÁÁxÁ w swz Fig. 3. Micrbial grwth (bld lines) related t CO prductin rate (dtted lines) fr seasned prk meat at different temperatures. w yw w w ƒ ƒ, vw ƒ, CO y w wš w. w š» w Lee w š w mdel w 11). CO š, Fig. 3. CO (dm CO /dt) ƒw ù z w. dm CO /dtƒ ƒ» wš. š dm CO /dtƒ 0l ƒw» w ƒ 10 7.5 ~10 CFU/g w 8. q t t w w d CO l w w ƒ w kw ƒ. Guerzni 1) vial ü w ³ CO eƒ e w» wš šw, w.. q t t sƒ l y yw CO (dm CO /dt)ƒ 0 l ƒw» w tw ƒ» w yw q t w y wš w. CO d m l xwš, CO d w. wì s q w t y wì dw. CO dwš s t dw, s ü CO y(d[co ]/dt)» wƒ ƒwš, ƒ l w» w(fig. 4). d[co ]/dtƒ ƒw» w ü w 5.9 10 7.8 CFU/g t w ùkü w ùkû. š s ü CO.1% w. w t t wì w, q t s CO y»ù y CO y» ƒ. s ü CO d sƒ/ ƒ p CO (,») wù, yƒ ƒ». t CO p wš s, headspace v»,» w p CO w w t p ww ƒw ƒ. Fig. 4 w CO % tw wš w w. wr CO y(d[co ]/dt)» ƒ w t r. w d CO yl y w ƒ lgic sensr l ƒ w. w Fig. 4 sensr ƒ wù d w d CO y ƒ niseƒ ƒ yj e Fig. 4. CO cncentratin ([CO ]) and its change rate ([CO ]/ dt) f seasned prk meat package related t micrbial grwth. 300 g fd in 1 L jar with 70 ml f free vlume. : micrbial cunt; : micrbial cunt estimate (10 7.8 CFU/g) at utbreak f d[co ]/dt.
Vl. 17, N. (011) CO d w 37 Fig. 5. CO cncentratin ([CO ]) and its rate ([CO ]/dt) f seasned prk meat package expsed t dynamic temperature cnditins. 300 g fd in 1 L jar with 70 ml f free vlume. : micrbial cunt; : CO cncentratin measured by GC; : micrbial cunt estimate (10 7.0 CFU/g) at utbreak f d[co ]/dt; : CO cncentratin (.%) at utbreak f d[co ]/dt. ƒ vw. w ƒ x wš d signal w š» s» dl tw w mw(fig. 5). d[co ]/dt» ƒ(.) 10 CFU/g ü 7 š,. w ƒš, CO.% ù kù Fig. 4 ew, CO % w w w ƒ. Guerzni t w 7) s vial z ³ l CO w w. t qt š» s w d CO w w lgic w. lgic q t w vƒ, vw yƒ ƒw ƒ. q t wù š» w s ü CO d w šwš ƒ yw. tl CO y s ü CO yƒ ƒw» w w t wš, t w ùkû. p CO, CO y» ew. lgic CO dwš l w sensr l w ƒ y. w (y 009-007080) w,. šx 1. Wijtzes, T., Van't Riet, K., Huis in't Veld, J.H.J. and Zwietering, M.H. 1998. A decisin supprt system fr the predictin f micrbial fd safety and fd quality. Int. J. Fd Micrbil. 4: 79-90.. Lee, D.S. 009. Packaging and the micrbial shelf life f fd. In: Rbertsn, G. (Ed.), Fd Packaging and Shelf Life. CRC Press, Bca Ratn, FL, USA, pp. 55-79. 3. Taukis, P.S. and Labuza, T.P. 003. Time-temperature indicatrs (TTIs). In: Ahvenainen, R. (Ed.), Nvel Fd Packaging Techniques. Wdhead Publishing Limited, Cambridge UK, pp. 103-16. 4. Sutherland, J. 003. Mdelling fd spilage. In: Zeuthen, P. Bgh-Srensen, L. (Eds.), Fd Preservatin Techniques. Wdhead Publishing, Cambridge, UK, pp. 451-474. 5. Kim, H.K., An, D.S., Yam, K.L. and Lee, D.S. 011. Package headspace cmpsitin changes f chill-stred perishable fds in relatin t micrbial spilage. Packag. Technl. Sci. 4: 343-35. 6. Guerzni, M.E., Lancitti, R., Trriani, S. and Dellagli, F. 1994. Grwth mdelling f Listeria mncytgenes and Yersinia enterclitica in fd mdel systems and dairy prducts. Int. J. Fd Micrbil. 4: 83-9. 7. Guerzni, M.E., Gardini, F. and Duan, J. 1990. Interactins between inhibitin factrs n micrbial stability f fruit-based systems. Int. J. Fd Micrbil. 10: 1-18. 8. Neethirajan, S., Jayas, D.S. and Sadistap, S. 009. Carbn dixide (CO ) sensrs fr the agri-fd Industry-a review. Fd Biprcess Technl. : 115-11. 9. Krtcenkv, G. 007. Metal xides fr slid-state gas sensrs: what determines ur chice? Materials Science and Engineering B 139: 1-3. 10. vn Bültzingslöwen, C., McEvy, A.K., McDnagh, C., MacCraith, B.D., Klimant, I., Krause, C. and Wlfbeis, O.S. 00. Slgel based ptical carbn dixide sensr emplying dual luminphre referencing fr applicatin in fd packaging technlgy. Analyst 17: 1478-1483. 11. Lee, D.S., Kim, H.K., An, D.S. and Yam, K.L. 011. Mdel fr estimating CO cncentratin in package headspace f micrbilgically perishable fd. J. Fd Sci. Nutri. In press. 1. Guerzni, M.E., Piva, M. and Gardini, F. 1985. Prpsal f a rapid HS-GLC methd fr micrbilgical cntrl f fds. LWT-Fd Sci. Technl. 18: 18-13.