How can kiwis cause trouble in a milkshake?

Questions:

Why can it be problematic to make milkshakes with fresh kiwi? How can dairy products still be made with kiwis? Is there a difference between green and yellow kiwis?

You need for the experiment

  • one
    green
    and one
    yellow
    kiwi (gold kiwi)
  • 200 ml boiling hot water
  • 200 ml milk
  • 4 glasses
  • 4 teaspoons (one per glass, do not swap them)
  • 4 Post-its for labeling the glasses + pen
  • 2 cutting boards and 2 kitchen knives
  • optional 1 small sieve (to pour off the hot water from the kiwis)
  • 1 blender or immersion blender with container
  • if necessary, some sugar (to sweeten after the experiment is completed)

Conducting the experiment:

  • Label four glasses with: “yellow kiwi fresh + milk”, “green kiwi fresh + milk”, “yellow kiwi scalded + milk”, and “green kiwi scalded + milk”.
  • Peel the kiwis, halve them, and set one half aside.
  • Put the yellow kiwi half into a container with 50 ml of milk and blend it into a shake. Pour it into the labeled glass and wait at least 5 minutes before tasting.
  • Clean the immersion blender and the container very well and repeat the experiment with the green kiwi half. Clean the immersion blender and the container very well again!
  • Cut the second kiwi halves on two different cutting boards with two different knives into as small pieces as possible. Put them into their respective labeled glasses.
  • Pour hot water over these pieces in both glasses, let them steep for at least four minutes, and carefully pour off the water. (Use a clean spoon or a clean sieve if necessary.)
  • Blend the scalded green kiwi pieces with 50 ml of milk into a milkshake and pour it back into its glass.
  • Clean the immersion blender with the container and now prepare the milkshake with the scalded yellow kiwi.
  • Now taste everything after at least 5 minutes each and note the taste.
  • What conclusions can you draw?

Evaluation:

Note what conclusions you can draw from your taste experiences. What answers can you give to the questions asked at the beginning? Research what enzyme reaction takes place in this experiment, or read our explanation.

Finally: Now you know how to make a delicious kiwi milkshake and can prepare more of them. The bitter samples are not harmful to health and can still be drunk with a little sugar to avoid wasting food. But: Everyone is differently sensitive to bitter substances.

Tip: You can do another exciting experiment with gummy bears and green kiwis. Puree the kiwi and put it in a freezer bag with some gummy bears. Put water with gummy bears in a second freezer bag. Observe after a few hours what happened to the gummy bears. This experiment helps to understand how digestion works in the stomach.

Tip 2: If you want to find out more about annoying enzymes, take a look at the experimental series on kiwis and pineapple with milk and oat milk.

To the explanation