Itiye elimnyama, elaziwa ngokunambitheka kwalo okucebile futhi eliqinile, yisiphuzo esidumile esijatshulelwa izigidi emhlabeni jikelele. Esinye sezici ezithakazelisayo zetiye elimnyama umbala walo obomvu ohlukile lapho likhiqizwa. Lesi sihloko sihlose ukuhlola izizathu zesayensi ngemuva kombala obomvu wetiye elimnyama, sikhanyisela izinqubo zamakhemikhali ezifaka isandla kulo mkhuba.
Umbala obomvu wetiye elimnyama ungabangelwa ukuba khona kwezinhlanganisela ezithile ezibhekana nokuguqulwa kwamakhemikhali phakathi nenqubo yokwenza itiye. Izinhlanganisela eziyinhloko ezibhekene nombala obomvu ama-thearubigins nama-theaflavins, akhiwa nge-oxidation yetiye polyphenols ngesikhathi sokuvutshelwa noma inqubo ye-oxidation itiye elimnyama elidlulayo.
Ngesikhathi sokukhiqizwa kwetiye elimnyama, amaqabunga etiye abhekana nochungechunge lwezinqubo, okuhlanganisa ukubuna, ukugoqa, i-oxidation, nokomisa. Kuphakathi nesigaba se-oxidation lapho ama-polyphenols etiye, ikakhulukazi ama-catechin, ethola i-enzymatic oxidation, okuholela ekwakhekeni kwama-thearubigins kanyeamaflavin. Lezi zinhlanganisela zinesibopho sombala obomvu ocebile kanye nokunambitheka kwesici setiye elimnyama.
Thearubigins, ikakhulukazi, izinhlanganisela ezinkulu ze-polyphenolic ezinombala obomvu-nsundu ngombala. Akhiwa ngokusebenzisa i-polymerization yama-catechin namanye ama-flavonoid akhona emaqabunga etiye. I-Theaflavins, ngakolunye uhlangothi, iyinhlanganisela emincane ye-polyphenolic ebuye ibe nomthelela embala obomvu wetiye elimnyama.
Umbala obomvu wetiye elimnyama uqiniswa nakakhulu ukuba khona kwama-anthocyanins, okuwumbala oncibilikayo emanzini otholakala kwezinye izinhlobo zetiye. Lezi mibala zingadlulisela umbala obomvu etiyeni eliphekiwe, lengeze kuphrofayela yalo yombala jikelele.
Ngaphezu kokuguqulwa kwamakhemikhali okwenzeka ngesikhathi sokucubungula itiye, izici ezifana nezinhlobonhlobo zezitshalo zetiye, izimo ezikhulayo, nezindlela zokucubungula nazo zingathonya umbala obomvu wetiye elimnyama. Isibonelo, izinga le-oxidation, ubude besikhathi sokuvutshelwa, kanye nezinga lokushisa lapho amaqabunga etiye ecutshungulwa khona konke kungaba nomthelela kumbala wokugcina wetiye eliphekiwe.
Ekuphetheni, umbala obomvu wetiye elimnyama uwumphumela wokuhlangana okuyinkimbinkimbi kwamakhemikhali amakhemikhali kanye nezinqubo ezihilelekile ekukhiqizeni kwawo. I-Thearubigins, i-theaflavins, nama-anthocyanins yiwona abambe iqhaza elibalulekile kumbala obomvu wetiye elimnyama, ngokwakheka kwawo nokusebenzisana kwawo ngesikhathi sokucubungula itiye okunikeza umbala wesici nokunambitheka kwalesi siphuzo esithandekayo.
Izithenjwa:
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Jilani T, Iqbal M, Nadeem M, et al. Ukucubungula itiye elimnyama kanye nekhwalithi yetiye elimnyama. J Food Sci Technol. 2018;55(11): 4109-4118.
Jumtee K, Komura H, Bamba T, Fukusaki E. Predication of Japanese green tea ranking by gas chromatography/mass spectrometry-based hydrophilic metabolite fingerprinting. J Biosci Bioeng. 2011;111(3): 255-260.
Komes D, Horžić D, Belščak-Cvitanović A, et al. Ukwakheka kwe-phenolic kanye nezakhiwo ze-antioxidant zezinye izitshalo zokwelapha ezisetshenziswa ngokwesiko ezithintwa isikhathi sokukhipha kanye ne-hydrolysis. I-Phytochem Anal. 2011;22(2): 172-180.
Isikhathi sokuthumela: May-09-2024
