Darker - Similar Seasonings

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Hello all, I’ve made 4 small batches of small 35-38mm casing dry sausages. All have similar seasonings. What I’ve noticed is after 1 week drying, 3 appear to be darker, while the 4th (Saucisson sec au Beaufort) appears to be pink.

Any ideas? I’m still working out some issues with fridge and air flow being a little too much, but overall I’ve been quite successful.

I’ve tried posting pictures, but thus far I’ve been unsuccessful.

Thank you for any help!