添加 is read as てんか (tenka) and means addition.
てんか
tenka
てんかぶつ
additive
てんかぶぶんようそ
included subelement
てんかようそ
inclusions
てんかざいきょうきゅう
additive supply
てんかざい
addition agent
すいそてんか
hydrogenation
むてんか
additive-free
ふくごうてんか
compound addition
しょくひんてんかぶつ
food additive
かがくてんかぶつ
chemical additives
すいそてんかゆし
hydrogenated fats and oils
さんそてんかこうそ
oxygenase