Lactose

[NickMoore]

Hi All, does anybody know whether lactose converts to lactic acid in a fermenting beer?

[James L]

As far as i know, lactic acid is only produced by animals/people from sugar when there is a lack of oxygen in the body.... Plants/bacteria produce a lovely thing called ethanol instead...

Also i dont think that yeast have the necessary enzymes (beta-galactosidase) required to break down lactose, they can break down fructose, sucrose and glucose... but not lactose

So to answer your question.... no... lactic acid will not be produced

[Trough Lolly]

Snap!

Cheers,
TL

[James L]

Anything to do with ethanol/fermentation that i learnt in Biochemistry kinda stuck for some reason...

[NickMoore]

Thanks James for the prompt reply. Lactose is converted to lactic acid during the fermentation process of dairy products such as cheese, yoghurt etc - that's why people who are lactose intolerent (such as me) can eat cheese because our bodies can process the lactic acid, but not lactose.

I know brewing yeast doesn't ferment lactose, but I was wondering if it went through a conversion to lactic acid anyway by some other means whilst everything about it was fermenting.

I'm soon to make an alcoholic ginger beer that calls for lactose, and I was just wondering whether it was going to have me doubled up in pain

[Trough Lolly]

Ginger beer with lactose?!
I'm assuming that the recipe has lots of dextrose or sucrose in it and they want to add lactose to add sweetness to the final product???

[James L]

yeh... they are two separate processes....

lactic acid procduction is based on energy processes in the body (oxidative phosphorylation if i remember correctly). when there is no oxygen in the body, in order to produce more energy, it cannot simply breakdown the glucose with oxygen to produce energy and carbon dioxide, it derives its energy by anerobically turning glucose to lactic acid... Every body should be able to do this

Where as lactose removal in the body is based on the digestive system, lactose i think is a mixture of two simple sugars, but if you dont have the means to break down those sugars that will be in the ginger beer you want to make, you will be in a spot of bother...

If you were adding lactate you would be fine (as lactate is the conjugative base of lactic acid). but i think your beer would taste shit..

[NickMoore]

Here's the receipt Lolly ...

Ingredients:
• 2kg glucose/dextrose *
• 500g malt extract *
• 500g lactose *
• 100g to 200g crushed or grated fresh ginger (vary to suit your own taste)
• Up to 4 lemons, sliced or chopped fine including peel (optional)

[lethaldog]

From my understanding the only thing that lactose gives to a fermented beverage is extra sweetness