Hard apple cider
I found some unpasteurized apple cider at my co-op this morning. I'd like to serve hard cider with my dessert at a dinner party this Saturday night - any idea on how long it'll take this half-gallon of goodness to go hard?
You won't get hard cider by then.
It usually takes mine about 3-4 weeks in the frig (if I don't assist it by pouring in the dregs of a previously fermented container).
If you were to try to ferment it at room temp, you may get nasty flavors: yeasts develop different flavors at different temperatures, because different acids are produced at different temperatures. Cider is, so far as I am aware, fermented at low temps (it's also much safer that way, too).
So, I'd hold onto it for Thanksgiving. Shake it up every day or so, to move the solids around. When the container starts to bulge, it's starting to ferment. You can open the container to let out some of the gas.
Also, cider fermented this way does necessarily taste hard in the same way as apple jack.
I have been a professional hard cider maker for an award winning Hudson Valley cider maker. You don't make it in the fridge. You need several months to get a good hard cider. Minimum time is a few weeks. one to two weeks for primary fermentation, then after removing the cider from the yeast and sediment (racking) it needs a few weeks to months of secondary fermentation and aging to mellow it.
You really can't make a good cider using store bought sweet cider because it doesn't have enough malic acid, it will be insipid and weak tasting, especially this year in the northeast since the sugar levels in the apples are so high. Hard cider apples are very acidic, a blend of apples is used to make hard cider and much care is used to make sure the acid levels are high enough.
You also need to buy a good hard cider yeast, using any old yeast or beer yeast will give you off flavors.
You don't need really low temps, it needs to start at a higher temp (65-70) and then when fermentation is underway the temp can be lowered. 55-65 degrees is good but up to 70 is ok... higher and you may get a darker tasting "Country Style" cider with rich butterscotch flavors.
Making it in the container instead of a proper fermentation setup will greatly increase the chance of poor tasting cider.
That said... it's still fun to play around with a gallon jug and trying to make your own. Do a google search on hard cider making and see what comes up.
Oh by the way... hard cider doesn't go very well with most sweet deserts because it is tart and acidic.