Need help with the meaning of つなぎには in this sentence [Cooking/ Cuisine]


There is a sentence about cooking here. Looks like this dish is hamburger
steak (?) and this character is cooking in his house to treat someone (A-san)

> 挽肉ではなく固まりの肉を包丁で微塵になるまで叩き切り、焦げないように飴色になるまで炒めた玉ねぎと混ぜ合わせてある。
>
> 味付けは塩と胡椒と、たっぷりのナツメグ。 **つなぎにはパン粉ではなく、砕いた麩を使うのがうまみたっぷりの肉汁を外に逃がさない秘訣だ** 。
>
> ジュウジュウと食欲を誘う音色といい香りが漂う中、焼き上がったハンバーグをA-sanが並べてくれた皿へと鼻歌交じりに盛りつける。​




> To thicken it (make it stick together), instead of panko, use crushed _fu_
> (which I guess is like bread crumbs); that's the secret of keeping meat
> liquid with lots of good flavor. (alternatively: locking in richly flavored
> liquid that oozes from the meat)

[つなぎ](https://jisho.org/word/%E7%B9%8B%E3%81%8E)

> Noun  
>  3. thickener (e.g. in cooking); thickening; liaison

