There are some immediate remedies that available in our kitchen. It depends on how meticulous you are when it comes to removing stains on your Tupperware.

Baking Soda

Sprinkle baking soda in the container and work into the stain with a moistened paper towel or cloth. The stain should lift off immediately.

Lemon Juice or Calamansi Juice

Tougher stains can be removed by squeezing lemon juice or calamansi juice on the area and placing the container in the sun until the stain dissolves or rinsing with warm water after soaking for 30 minutes. It also removes undesirable odors in the plastic container.

White Vinegar

Using white distilled vinegar in the oldest way of cleaning and yet still the best cleanser. Cleaning with vinegar is much safer than using commercial products. It can be used depending on how tough the stains are. Mix white vinegar with equal part of warm water then leave the solution on it for 30 minutes and rinse. You can add in the mixture, the dish washing soap and baking soda soaked overnight for strong stained Tupperware. It can be sprinkled or sprayed as you wish. It does not only remove stains but also eliminates bad odor.

Salt

I'm using a mixture of iodized salt and milk powder as body scrub. But, salt can also remove stains on your plastic products. Dissolve salt in lukewarm water, then you wet/moistened a soft cloth using the solution and wipe it on the stained area. Soak the solution for better results.

The above helped me a lot in my chores cleaning. I hope they will also work for you. Remember the milder the solution, the lesser the risk and harshness it will give to your stuff. Also, don't rub hard and scratch your Tupperware to avoid harsh effects on the surface.