Handling & storage of opened dried yeast, group buy?

[Stan's Brew]

In my experience 1 packet of dried yeast will brew 30 litres of session strength ale without issues reaching its attenuation potential. What about custom size batches of 35-45L where I don't want to use 2 packets to avoid overpitching and I don't want to waste nearly a whole packet when I only need up to 5 grams from the packet?

CML sell 100g and 500g size packets and other homebrew shops sell in 500g blocks, 100g is more economical than 2 packets! 500g might be a bit on the overkill side, maybe a group buy and distribution would be a way of keeping costs down - is anyone interested in this?

So, to the question, is it safe to store opened dried yeast long term, I can vacuum pack custom sizes from a larger amount, what is the risk of infection, other than usual sanitary handling procedures would vaccum packing suffice?

Looking at Kveik rings it appears Kveik is highly resistant to infection when air dried used in this manner (or any other form of drying Kveik that I've seen), is this true for non-kveik yeasts that we use?

I've used liquid yeast and built stir plate starters in the past, but due to the additional time and steps involved I moved back to dried when the market exploded into the dried variety we have today. Liquid yeast wrangling is very good for economic re-use and fermenting generation improvements, plus the additional variety of flavours, this discussion is not about liquid yeast however

 

[Pennine]

I often use half packets of yeast and just tape them for the next time. I have used some 6-12 months later and have not had any issues. I think one of the potential issues is exposure to moisture. I don't think contamination is a big deal either.

 

[CaptAwol]

I buy the 500g packs and vacuum pack keeping it in the fridge, with the pack simply cut open at the end pour out required amount and vacuum reseal, never had any problems and I've been doing this for a few years

 

[MrRook]

Muntons comes in 6 gram packs, a perfect size to up your pitching amount for slightly larger batches.

 

[Northern_Brewer]

The other attraction of buying in bulk is that there's a few strains like Fermentis LA-01 low alcohol, which aren't available in retail packs, and the very new ones like Novalager where they're planning to do retail packs but it just takes them a while to organise after the release of the bricks, so that can be another reason to do it.