A sarrafa nakore shayikawai an raba shi zuwa matakai uku: gyarawa, jujjuyawa da bushewa, wanda mabuɗin shine gyarawa.Sabbin ganyen ba a kunna su kuma aikin enzyme ba ya aiki.Daban-daban sinadarai da ke ƙunshe a cikin su suna fuskantar sauye-sauye na zahiri da sinadarai a ƙarƙashin yanayin rashin tasirin enzyme ta aikin zafi, don haka suna samar da halayen ingancin kore shayi.

Gyarawa yana taka muhimmiyar rawa a cikin ingancin koren shayi.Ta hanyar babban zafin jiki, an lalata kaddarorin enzymes a cikin sabbin ganye, kuma an hana iskar oxygenation na polyphenols don hana ganye daga reddening;a lokaci guda kuma, wani ɓangare na ruwan da ke cikin ganye yana ƙafewa, yana sa ganyen ya yi laushi, yana haifar da yanayi don jujjuyawa da siffa.Tare da ƙamshin ruwa, ƙananan abubuwa masu ƙamshi masu tafasa tare da ƙanshin ciyawa a cikin sabobin ganye suna canzawa kuma suna ɓacewa, don haka inganta ƙanshin shayi.

Sai dai teas na musamman, ana yin wannan tsari a cikin injin gyarawa.Abubuwan da ke shafar ingancin gyaran gyare-gyare sun haɗa da zafin jiki na gyaran gyare-gyare, adadin ganye, nau'in na'ura mai mahimmanci, lokaci, da kuma hanyar gyarawa.Su duka ne kuma suna da alaƙa kuma suna ƙuntata.

Abubuwan da aka shafa da nau'in shayi, hanyoyin gyaran su ma sun bambanta, ciki har dasoyayyen gyarawa, Gyaran bushewar rana, da gyaran tururi.