American pale ale brewing

 First trial

Malt grain 500g

Boil water, 4 Litres 

Grains in cloth bag

Boiling around 100 deg c

Wort boiling

Cold water bath

Using metal filter ( is it really necessary to filter at all?)

Carboy

水封 排氣閥 One way valve 

Malting enzymes:

Beta Amylase and Alpha amylase has major role  for maltose conversion.

Why 68 °c?

Beta-amylase has an optimal range pH 5.2 to 5.6

Reference 

Control mash temperature 

4L of water used

3L of wort made

2L(2.5L?) to carboy 

pH value changes from Hanna instruments 

Beerandbrewing water and wort pH:

You might recall from high school chemistry class that pure distilled water has a pH of 7.0, but most municipal water sources have a higher (slightly alkaline) pH above 7.0, due to minerals they pick up from ground and surface sources.

Grains, in contrast, are acidic, meaning they will lower the pH of the water/grain mixture. Dark roast malts are very acidic and will have the largest effect, while pale malts are only slightly acidic.

So when we mix our slightly alkaline water with our acidic grains, we get a pH that is often in the range of 5.0–7.0. That will depend on how alkaline the water was to start with, how much acid the water itself can absorb (which is measured by the water’s residual alkalinity), and how much dark vs. light malt we use.

Since we want to get the mash pH down to 5.2–5.6, we often need to use additional acid to drive it down further. 

Hops are added for bitterness and aroma, and utilization of the bittering substances [α-acids] takes place at the elevated temperature of the boil.  Heat and wort pH will affect the isomerization of the α-acids to iso- α-acids with a slight advantage of higher utilization at higher wort pH [5.8]

Checking the pH of yeast before repitching it into the wort is recommended.  A tired yeast slurry will have a higher than normal pH [>4.5] due to cytoplasm released by autolysed yeast.  Healthy yeast will respond positively to clean, cold, oxygenated wort with adequate nutrients and no competition. 

5.2 pH stabilizer:

The 5.2 stabilizer is a blend of two salts. They are neutralized versions of phosphoric acid. They are monosodium phosphate (Na H2 PO4) and disodium phosphate (Na2HPO4).