Infection with lacto

Hi
This is Edgar from Mexico
I hope you can understand me due to my English.

I brew a Tamarindo beer, this is a very common fruit in Mexico, and I decided to brew.
My question is, how do I know if I have infection with Lacto?
The point, Tamarindo is a very acid fruit, so every time that I brew pH is very low. But some of my friend told me that was infected with lacto. Because he tasted very acid.
Smelling wasn't bad, it was opposite.
However, I repitched the same yeast from tamarindo to another wort. And now I'm worried if I have two contaminated batches or not.
Do you kno some test to identify if my beer is ruined or not?

lacto infection is going to look like it has a slimy white film over the top with little bubbles from the co2 trying to escape but getting caught under the slime. It also tastes like sour green apples and tastes too bad to drink. The general advice when facing a lacto infection is to drink it fast before it tastes bad. Another idea is going to be consider taking the beer to the next step and infecting it more to make something interesting. Brett if i remember correctly will kill lacto.

brett will not kill lacto - in fact both are alive and well in flanders reds, lambics, etc: http://www.wyeastlab.com/rw_yeaststrain_detail.cfm?ID=194

how and when did you add the tamarindo? did you sanitize it? did you add it to secondary? what sort of beer are you brewing - is it a strong (big) beer?

most fruit have lacto and/or other yeasts on their skin. infection will depend on how you treated the fruit, what you added it to, and when you added it.