Observations and results
Did the tofu cubes in the cup with the vinegar become the most dyed? Were the other tofu cubes less dyed, but all dyed similarly to each other?
You should have seen the tofu cubes that were marinated in the cup with the vinegar/food dye/water solution clearly become the most dyed—or had adsorbed the dye best—compared with any of the other tofu cubes. Vinegar is an acid, like lemon juice and orange juice. Acids can cause foods such as meats to be broken down, or tenderized. (You may have heard people warn not to use too much vinegar in a marinade. This is because the acid can tenderize the food so much that it becomes mushy!) When vinegar is used in a marinade, it breaks down the food’s surface and lets the marinade be adsorbed there. Salt works well in marinades for meat, too, because it helps break open the cells, allowing the marinade to penetrate into the tissue. Sugar in marinades helps the food taste sweet, but does not help marinades be adsorbed into food as much.
It is not recommended to eat the tofu cubes used in this activity. You could compost them or throw them in the trash. If you used chicken breast or other meat, discard it in the garbage and be sure to wash everything that came in contact with the raw meat, especially if you used raw chicken, which might have salmonella.
More to explore
Marinade Science—How Marinades Work, from About.com Home Cooking
The Secrets and Myths of Marinades, Brinerades and How Gashing Can Make Them Work Better, from AmazingRibs.com
Fun, Science Activities for You and Your Family, from Science Buddies
Flavor That Food! Exploring the Science of Marinades, from Science Buddies
This activity brought to you in partnership with Science Buddies