
Kiwi is a small, brown-skinned fruit with bright green, black-seeded flesh.
Tartness and a green color arrive together, and the enzyme arrives with them — which matters if there is dairy or gelatin in the build. Any soft tart fruit covers the flavor. The enzyme is a separate question and does not track the family in the way you would expect: see below.
Golden kiwi
A different species rather than a cultivar — Actinidia chinensis against the green fruit’s A. deliciosa. Yellow-fleshed, sweeter, smoother and much less acidic, so in a sour built on green kiwi it leaves the drink flat. It is also the one substitute that solves the enzyme problem: Hort16A carries no actinidin at all and SunGold about a quarter of the green fruit’s activity, which makes gold kiwi the safe choice beside dairy.
Kiwi berry
Smaller, smooth-skinned and far less juicy, with several times the protease activity of green kiwifruit rather than the same. Muddled it gives less liquid for its size. Treat it as the more aggressive option next to cream or gelatin, not the milder one.
Firm fruit ripens at room temperature and ripens faster next to a banana or an apple. Ripe kiwi keeps a few days refrigerated. It is ready when the fruit yields to a thumb the way a ripe peach does.