I am not too sure what you mean by manufacturers add 2.5% or 3% of alcohol to them? Can you provide a reference for this? There is no doubt that this question will generate lot's of opinions and a similar question was discussed in 2012 here: Haraam or Halal? - Coke and Pepsi contain 0.001% Alcohol
The general approach to this can be seen in two ways;
1) If alcohol is a stated ingredient then it is no doubt haram (except in medicine where no alternatives can be used).
2) If alcohol is not a stated ingredient or the product is advertised as alcohol free and the food (or drink) is generally unlikely to intoxicate you with the potential traces it 'may' contains then it would be too extreme to forbid yourself enjoying what has been provided to us. This theory does not stretch to Alcohol free beer however as it is mentioned in the ingredients or the small print that it has a very very small percentage which makes it haram.
Finally, it is always best to avoid what gives you doubt for what gives you certainty or in this case peace of mind.
And Allah knows best.