Instrumented bottles: Bottles are “Mangrove Jack” 500ml swingtops, with the polythene tops drilled and tapped vertically to accept an M5 gas fitting thread and a 2.5mm hole drilled obliquely through to the bottom surface of the swingtop. Each cap was fitted with an M5 to 6mm push-on SMC pneumatic fitting which in turn connected to an SMC 0 – 4 Bar miniature gauge, stated accuracy is 2% FS. Connecting 6mm tube is filled with dacron breather fabric and sterilised by autoclave. Bottles are filled with dummy tube in place which is then replaced with a pre-sterilised tube connector and the gauge.
Beer: All malt ale, OG 13.9 oP, FG 3.5 oP, ABV 5.7%, fermented with Danstar Nottingham @ 18 oC, 2 days rest at 18 oC once FG achieved, settled 2 days at ~10 oC (no finings, no dry hop), racked off ferment lees to priming vessel then warmed to 18 oC.
Priming: sterilised glucose syrup equivalent to 6.2 g/l glucose (in beer volume) expected final CO2 level 4.6 g/l. At 18 oC 4.6 g/l is equivalent to 263 kPa absolute = 162 kPa gauge.
Yeast: S.cerevisiae “Prise de Mousse” (Lalvin EC1118) at 2 x 10^ 6 cells per ml (beer volume), rehydrated in 10 volumes of water at 39 oC for 20 minutes with no stirring, remixed before addition to priming vessel. Water was standard Melbourne tap water prepared by boiling for 5 mins then cooling to 39 oC in water bath.
Priming and yeast added to beer in priming vessel then mixed / aerated by shaking vigorously. Decanted to 500ml swing top bottles with approx 20 ml headspace per bottle, caps sealed then bottles placed in fermentation oven at 18 oC.
Pressures observed daily until calculated final pressure (1.6 Bar) achieved on gauges. One section of bottles then moved to 10 oC room, remaining sections held at 18 oC.
Extension:
After three further days at 18 oC ( = 7 days total ) second section of bottles to be moved to 10 oC room. After seven further days ( = 14 days total ) third section of bottles to be moved to 10 oC room. After 7 further days ( = 21 days total) fourth section of bottles to be moved to 10 oC room.
Intention is to do blind triangle tastings to see whether there is a significant difference ascribable to total time at conditioning temperature.