Hi Natasha,
Thanks for posting your interesting question on Scibuddies. I will try to help you with planning a project in this area and designing appropriate experiments to test a hypothesis.
First off, let me say that I am not familiar with this specific science fair demonstration, but I get the idea from your description. However, as a research scientist and lab rat myself, I have to say that these experiments will not tell you anything about the effects of your test compounds on cholesterol. Pork fat (lard) does contain some cholesterol (95 mg per 100 g of lard,
https://en.wikipedia.org/wiki/Lard) but it is 99.9% fat. So, the experiments you read about really are showing an effect of these 'home remedies' on fat, not cholesterol.
Too much saturated fat in the diet has been linked to heart disease and cancer, so reducing it or neutralizing its effects could be beneficial. If you wanted to approach the project by asking if coriander juice, honey-garlic or apple cider vinegar might help to break down saturated fats, that would be OK, I think. You would need to do some reading online about this, however, and try to find out if adding these substances to food could help neutralize the bad effects of lard. Be careful where you get your 'facts', however, as the web is full of misinformation, especially with regard to diet and health.
Let me know what you would like to do in view of what I said and I can help you to come up with a workable hypothesis and some valid experiments to test it.
Best wishes,
Sybee