Oi. Your comment is a perfect example of why there needs to be more science education. At most, assuming you had more than 30 different kids you were working with, and formed proper double-blind controls, you would have ended up with a correlation (with a 95% confidence interval possible). A completely useless, pointless correlation that could not be used as the basis for anything. How does lemon juice interact with saliva? How about stomach acids? What is the metabolic pathway through which you would guess 'alkaline' would have any effect on any part of the rhinovirus particle?
Bad pop pseudo-science junk like your "experiment" is a hundred times worse than complete ignorance. If people are encouraged to use their intuition to try to figure out the answers to problems, we will end up back in a New Medieval Era. The explosive developments in every field of human endeavor over the past 300 years are based firmly in the principles of rejecting intuition in favor of intellectual rigor in critical thought. Our culture has devalued this to such a degree that most people would interpret this comment as an insult.
Adults and children alike are completely capable of understanding the rules of logic and how to form rational arguments without being tricked by the predictable errors (like assuming alkaline chemicals could interact in any way with viruses in the bloodstream) that our intuition always leads us into. It used to be dangerous, literally lethal, to trust your intuition. Had you tried your 'experiment' a hundred years ago or so, some of the children would have likely ended up dead (not through your fault, but due to malnutrition, lack of vaccines, no antibiotics, and reliance on intuitive 'cures'). Today, people can forge headlong into ignorance and irrationality thanks to the wide umbrella of protection that the intellectuals of the past 300 years have erected. If we continue to belittle their accomplishments by not even exerting the slight effort necessary to learn critical thinking and use it constantly, the infrastructure they built will eventually erode. And with it, every single thing which has ever given you a moment of comfort or safety in your life. None of them were the work of untested intuition. Every last one was created by a man or woman (or even child) who simply refused to believe what "felt right" in favor of what they could put together a rational argument backed by evidence to support.