TAP CHi CONG THlTtfNG
DUNG TANIN TRONG DICH CHIET LA TRA DE NHAN BIET FORMOL
CO TRONG THlJC PHAM
• TRUdNG THI NGOC CHINH
TOM TAT:
Formol la chat co hai cho sdc kh6e cua con ngu'di, du vSy vi loi ich kinh te ma hien nay nhieu ngu'di ban da suf dung formol cho vao thdc phim va ban cho ngifdi tieu dung su" dung bang ngay nbir: bun, phd . nham giup nhu'ng loai thi;fc pham nay giff dddc tdoi ISu hon. Vi vay, bai viet nghien cdu dung tanin trong dich chiet la tra de nhan biet formol trong cac thdc pham, giup ngifdi tieu dung co th^ tranh an ciic thdc ph^'m sijf dung formol nham bdo dam an toan cho sdc khoe ban than va ngirdi than. K^^t qua nghidn cdu cho thS'y, co dd'n 50% cac mlu khao sat c6 chda formol du'dc tim ra tii phifOng phap njiy.
Tif khoa: Formol, thdc pham sach, tri, tannin.
1. D§t va'n de
SlJ dung thiTc pham sach dang la nhu cau thiet yeu trong cuoc so'ng va ngay cang du'dc ngu'di tieu dung quan tam va siJ dung. Tuy nhien, ben canh do nhdng loai thu'c pham sach nay phai to't cho sdc khoe va khong cd cac chat boa hoc, cha't nbuom mau, cac cha't khong to't cho sdc khoe, tim mach... Vi vay, ra't nhieu nghien cdu da dddc de'n hanh nh5m tim ra cac giai phap giai quye't va'n de thdc pham co chda chat boa boc doc hai, trong dd cd cha't formol, mot loai cha't hda hoc gay nguy hiem cbo ngifdi su" dung.
Bun, phd la loai tbifc pham qua quen thupc va gan gui vdi ngifdi dan d Viet Nam. Tuy nhien trong nhu'ng nam gan day, viec trong bun, banh phd cd chda formol da trd thanh mot van de Idn
cua xa bdi. Cac tieu tbddng, ngifdi ban da cbo formol vao bun nbSm bao quan difdc lau hdn, sdi bun bong dep hdn ma khong quan tam de'n sdc khoe ngifdi tieu dung.
Vdi muc tieu tim mpt pbddng phap that sd ddn gian de cd the phat hien ra biin khong an toan - cd chda formol, tac gia da tien banh nghien cdu dung tanin trong dich chiet la tra de nhan bie't formol CO trong bun.
2. Phan tich
2.1. Cd'u tao, tinh chdt ciia formol 2.1.1. Formol Id gi'^
Formol ten day du la Formaldehyde la mpt cha't sat khuan manh, pha loang de tay ue' dung cu, nen dat va mdi trifdng bi nbilm kbuan nam
320 So 5 - T h a n g 4/2019
HOA HOC-CONG ff ! THIfC PHAM
moc, Formol thu'dng dddc cho vao thdc pham nham dc che c£c boat dong va tidu diet vi sinh vat, vi nam lam hdhong san pham, giup keo dai thdi gian bao quan thdc pham.
Trong y hpc, formol dddc dung de ddp va bao quan phu tang, xac che't va cac bo phan cd the dgng v5t hay ngddi. Vi formol tbddng d dang dung dich cd mau trong suo't gan gio'ng nhd mau nddc va sd dung vdi ham Iddng nhd nen viec kiem tra formol trong thdc pham la v6 cung khd khan [3].
2.1.2. Cdu tao formol
Formol hay con gpi la formaldehyde - HCHO c6 c6ng thdc cau tao:
0 il H H
Nd ddn gian la aldehyde, do do formol co he thong ten methanal. Ten gpi chung xua't phat iii stf tifdng ddng \6i axit formic [5].
2.1.3 Tinh chdt
Formol la chat hdu cd de bay hdi, hay con gpi 1^ VOC (diing de chi nhffng hdp chat hffu cd dl dang lan toa vao khong khi), khong mau, mui cay soc, khd ngdi, tan nhieu trong nffdc.
Formol thupc nhdm quy hie'm cua cha't dpc cd khi nang gay che't dSt ngpt kbi nuot phai formol d nong dp cao. Formol de dang ke't hdp vdi cac protein tao thanh hdp chat ben, khong thoi rffa, khong 6i thiu, nhffng rS't khd tieu. Chinh vi vSy, nhilu ngffdi da sd dung no de giff thffc pham khoi bi ffdng, 6i thiu. Dac biet, formol du'dc lam dung ra't phd bien d c i c loai thifc phd'm nhd: bun, phd, thu'c pham...[5].
2.1.4. Anh hudng ciia formol den si^c khoe con ngudi
Do cd tinh sat khuan cao, vi vay khi dffa vao cd the con ngffdi formol lam suy giam be miln djch, lau dan tich tu trong cd the gay ra benh ung thif. Theo mpt thong ke tff benh vien Ung budu Trung ffdng: M6i nam, Viet Nam co them
150.000 ngffdi mac benh ung thff, trong do khoang 50.000 ngffdi mac b6nb do an uo'ng phai thffc pham bi nhidm chat boa hpc, trong do phan Idn CO formol.
Ngffdi bi nhiem ngp d6c formol qua dffdng deu hda hay ho ha'p se cd cac bien tddng sau day:
Viem loet, hoai tff te bao, cac bieu hien non mffa ra mau, ia chay hoac di tieu ra mau va cd the gSy tff vong ngay tffc thdi do truy tim mach. Lieu Iffdng formol trong khoang 30ml fa da cd the hai che't mot ngffdi.
Trong trffdng hdp nha't dinh cd the chuyen hda thanh cha't axit formic lam tang axit trong mau, gay thd nhanh, thd gap, bi ha nhiet hon me va cd the dSn de'n tff vong nd'u khong dddc cffu chffa kip thdi [3].
2.2. Tra vd thdnh phdn hoa hoc ciia trd 2.2.1. Tong quan ve cdy trd
Ten khoa bpc Camellia sinensis O.Ktze (Thea chinesis Seem). Thupc hp Che: Theaceae. Bo pban thu'dng dung la bup va la tra non, sao khd lam nffdc uong.
Tra la mot cay khoe, moc hoang va khong cat xen cd the cao tdi 10m hay hdn nffa, du'dng kinh thancd the tdi mffc mot ngffdi dm khdng xud\Doi khi moc thanh rffng g6 trdn nui da cao. Nhifng trong khi trong tia thffdng ngffdi ta cat xen de tidn vide hai nen cay chi cao nha't la 2m. Cay tra nhieu canh ngay tff go'c; la moc so le, khong rung;
hoa to trSng, moc d ke la miii rS't thdm, nhieu nhi;
qua la mpt nang thffdng cd ba ngan, nhifng chi con mot hat do cac bat khac b| teo di. Qua khai bang 16'i cat ngang, hat khdng phoi nhu, la mam Idn, CO chffa dau.
2.2.2. Thdnh phdn hda hoc cda trd Trong thanh ph^n hda hpc cua la tra cd chffa cha't cafein va hdp cha't polyphenol. Cafein la mot hdp chat alcaldid va la chat kich thich chu yd'u trong la tra. Ndi chung, alcaloid khd tan trong nffdc lanh.
Hdp cha't polyphenol trong tra giiip tra cd vi chat, dd la hdp cha't cd nhieu chdc nang dddc ly do'i vdi con ngffdi. Tra chia thanh 5 loai, nhieu nha't la cac loai flavanol, trong dd chu ye'u la cha't
So5-Thang 4/2019 321
TAP CHI CONG THUDNG
tanm, chiem 60 - 80% tong Iffdng flavanol. Tanin:
la hon hdp catechin (30 - 35%). Theo kd't qua nghidn cffu d che ta cd: 37,77% d la thff nha't, 34,74% d la thff hai, 30,77% d la thd ba, cuong chda 25,56% tanin. Tanin dffdc xem la thanh phan quan trpng thff hai trong cay tra. Gan day, ngffdi ta da xac dinh cac thanh phan polyphenol trong che bang phffdng phap sac ky. Nhieu loai catechin da dffdc pban lap tff pban doan chie't bang acetate etyl. Hdp cha't polyphenol trong cay tra thupc nhdm tanin khong thuy phan dffdc hay cdn gpi la nhdm tanin ngUng tu, tanin pyrocate- chin [1].
2.3. Ca sd cua vifc sd dung tanin trong dich chie't la trd de nhqn Met formol trong bun
Tanin cd vi chat lam se Iddi. Ngoai ra, chiing cd thd' bi enzym oxy hda thanh cac hdp chat cd mau do hoac nau. Day la hai dac diem quan trpng nha't dffdc tan dung trong qua trinh chd'bid'n la tra. Ta't ca cac thuoc tinh cd ban cua nffdc tra nhif mau, vi, mui, deu lidn quan it nhidu dd'n tanin va cac cha't dan xuat cua tanin.
Tanin cd vi dang, nhffng trong qua trinh cbd'
bid'n thi vi dang ban dau lai chuyen thanh vi chat dd chiu. Hdp cha't tanin ddng vai trd quan trong nha't do'i vdi chat Iffdng che thanh pham.
3. Phrfdng phap thifc hidn va kd't qua dat diTdc
3.1. Nguyen li?u
Mlu bun thff nghidm, tra, HCI dac.
3.2. Phuang phdp thtfc hien
Dd'i vdi tra: Pha mot co'c tra dam dac sau do la'y pban nu'dc tra d trdn mat. Bun: Trung bun trong nffdc sdi va giff lai nffdc trung bun.
Pha bdn hdp nffdc trung bun, nffdc tra va axit HCI dac (nong dp 32%) theo ty Id tra/ nffdc bun/
axit HCI la: 2/2/1. Saudd dun ndng each tbdyhdn hdp trdn trong thdi gian tff 7 - 10 phut.
3.3. Ke't qud nhqn dUac
Sau khi dun ndng each thuy h6n hdp gom nifdc trung bun, axit HCI dac va tra ta nhan dffdc ke't qua nhff Hinh 1.
Cd the quan sat bang mat thffdng dd' nhan thay trong ong cd xua't hien chat mau do gach khong tan trong nffdc.
}^nh 1: Phan Ong ket tOa <3e nhgn biet co formol
322 So 5 - T h a n g 4/2019
HOA HOC-CQNG NGHE THlfC PHAM
Sff xua't hien chS't khong tan la do sff kd't tua khi dun ndng hdn hdp tren va phan ffng do gpi la phan dng Sdasny. Dd cung chinh la dafu hieu quan trpng dd' nban bie't cd sff cd mat cua formol CO trong thffc pham.
Cac kd't qua cung cbo dia'y trong t§'t ca cac mlu bun Iffdng formol trong bun tff 2 - 10ppm(l ppm = mg/lit).
3.4. Phdn tich ket qud
* Giai thich phdn dng Stiasny
Chat tanm cd dong tra la tanin pyrogallic: La nhffng este cua glucid, thffdng la glucozd vdi mpt hay nhieu axittrihidroxibenzencacboxylic.
Tanin pyrocatechic: Tanin nhdm nay dffdc hinh thanh do sff ngffng tu tff cac ddn vi flavan-3-ol hoacflavan3,4-diol.
Tanin pyrocatechic phan ffng tao tua vdi phffc chat formol va HCL la do nd cd ca'u tao tff cac ddn vi flavan-3-ol hoac flavan 3,4-diol dffdi tac dung cua acid hoac enzyme nd se khong bi thuy phdn ma tao thanh chat do tannin hoac phlobapben.
Phlobaphen it tan trong nffdc nen Tanin pyrocatechic se tao tua khi cho HCL vao.
* Gidi thich ket qud da thu duac
Theo [3] gidi ban vIn con an toan cho con ngffdi trong khong khi la it hdn 2 ppm. Thi nghidm trdn chuot cho thay chupt so'ng trong moi trffdng
formol vdi nong dd 6 de'n 15 ppm din dd'n bj ung thff mo. Cac nghien cffu cQng cbo tha'y formol cd the' gay ra cac van d^ vdi gan, tuy va phdi.
Qua thd nghiem cd de'n 50% mlu bun sau khi lam thi nghiem co xua't bien chat trung hdp mau do gach khong tan trong nffdc, dieu dd cho thS'y trong biin cd mot Iffdng formol khong nho va cd th^ gay bai cho cd the ne'u sd dung lau dai.
4. Kd't lu$n
De bao vd sffc khoe ngffdi tieu dung, nhieu nffdc trdn the' gidi da nghidm cam vide dung formol de lam chd't bao quan thffc pham va do uo'ng, kd' ca thffc an chan nuoi gia sue an thit.
Ngffdi ta chi cbo phep bao quan cac cha't khong dd' an uo'ng nhffng cung qui dinh rat nghidm ngat ve gidi ban cho phep va phai bao dam an toan 100%
cho moi trffdng sinh boat cua con ngffdi.
Viec quan ly su' dung hda chat trong thffc pham d Viet Nam hien nay con gap rat nhieu khd khan. Ndn vide tff bao vd sffc khoe cua chinh ngffdi tidu dung la quan trpng. Chinh vi vay, phffdng phap dting tra de nban bid't formol cd trong thffc pham rat ddn gian ma ai cung co the thffc hidn dffdc.
Ngoai bun, ta cd tb^ tim formol trong cac loai thffc pham khac nhff bun khd, hu tidu kho, banh phd de cd the tranh an, tff do cd the bao dam an to^n cho sffc khoe bang phffdng phap nay •
TAI LIEU THAM KHAO:
/. Bd Huy Bich, Ddng Quang Chung (2000). "Cdy thudc va dong vat lam ihudc Viet Nam". Nxh Khoa hoc v Ky thuat - Vien Duqc lieu.
2. PGS.TS Trinh Xudn Ngo (2007), "Cdy che vd ky thuat che bien". Nxh Khoa hoc tU nhien va cong nghe.
^•^"Ps://dantri.com.vn/suc-khoe/formol-huy-hoai-suc-khoe-con-nguoi-ra-sao-l 173239864.html '^•l^"P--^/l"anvan.nel.vn/luan-van/de-tai-ung-dung-vi-song-lrong-chiet-xuat-polyphenol-lu-cay-che-357857
^•^"pd/luanvan.nei.vn/luan-van/de-tai-phu-gia-thuc-pham-su-nguy-hiem-iiem-tang-60037/
^•f"'PS:dthanhnien.vn/gioi-tre/dung-hat-ca-phe-phat-hien-formol-trong-bun-4745.html
^•hltps://voer.edu.vrdm/fomandehit7c20f900d
^•'^l'ps://baomoi.com/vai-tro-cua-chat-tanin-trong-che7c/10442199.epi
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