Muaj tseeb koj yuav tsum tau soj ntsuam qhov tshwm sim no: yog tias koj tom (lossis txiav) ib qho los ntawm ib lub txiv av, nws cov nqaij yuav tsaus ntuj sai sai. Thaum pib dawb (los yog nrog qhov hloov maj mam pinkish tinge), nws yuav siv rau ib qho xim brownish. Ntxiv mus, txiv apples ntawm ntau hom sib txawv tsaus ntuj ntawm txoj kev sib txawv: ib qho nrawm dua, lwm qhov qeeb qeeb, thiab cov neeg kawm qib siab ntawm "tsaus muag" kuj tsis zoo li qub Vim li cas qhov no tshwm sim?
Qhov tseeb, txhua yam yog yooj yim thiab ntuj. Qhov tseeb yog tias ib cov kua (zoo li tag nrho lwm cov txiv ntoo) muaj ntau ntau cov microelements, nrog rau cov khoom siv uas zoo rau lub cev li hlau. Raws li koj paub los ntawm chav kawm ntawm Chemistry, hlau nyob hauv cov tebchaw tuaj yeem nyob hauv ob lub xeev oxidation: +2 thiab +3. Lub tshuab nqus cov kua muaj hlau, uas muaj lub zog oxidation ntawm +2. Yuav muaj dab tsi tshwm sim yog tias koj tom dua lossis txiav ib qho ntawm cov txiv?
Txoj kev sib xyaw ua rau nkag los rau hauv kev sib chwv nrog cov pa oxygen, thiab nyob rau hauv nws cov cawv nws yog maj oxidized. Qhov oxidation no yog nrawm los ntawm cov enzymes - oxidases thiab peroxidases, uas muaj nyob hauv cov kua txiv. Thaum yoov tawm los yog txiav, ntau cov kua txiv tso tawm, thiab cov enzymes uas tso tawm "nqis los rau kev lag luam". Raws li qhov tshwm sim, cov tebchaw ntawm ntau cov lus sib xyaw (oxides, hydroxides, ntsev, cov txheej txheem nyuaj) yog tsim nyob rau saum npoo ntawm lub sam thiaj, nyob rau hauv uas hlau tam sim no muaj oxidation lub xeev ntawm +3. Nws yog cov khoom sib txuas uas muab cov kua pulp ib brownish tint. Kev ceev ntawm kev tsaus ntuj nyob ntawm cov yam ntxwv ntawm cov kua ntau yam, uas yog, ntawm cov ntsiab lus ntawm cov kua qaub thiab kab kawm.
Kev sim ua tej yam yooj yim thiab tsis yooj yim tuaj yeem nqa tawm. Txiav hauv ib nrab thiab sai sai thov cov kua txiv qaub. Tom qab ib ntus, cov nqaij ntawm ib nrab hnub yuav tsaus ntuj, thaum cev nqaij daim tawv ob mus ntxiv. Vim li cas? Qhov laj thawj yog vim li cas cov hlau +2 ions ua ke nrog cov citrate ions, ua rau muaj kev sib txuam zoo thiab khaws cov qub oxidation xeev. Raws li, kom txog rau thaum cov kab sib txuas ua ke no puas lawm, cov hlau yuav tsis hloov lub xeev oxidation, thiab cov kua txiv kab ntxwv yuav tsis tsaus.
Tsis tas li ntawd, kua txiv qaub muaj ntau cov ascorbic acid - lub ntuj muaj zog antioxidant uas "khi" oxygen, tiv thaiv nws los ntawm "poob qis rau kev lag luam."
