Food Waste to Good Taste: top tip to use your eggshells

‘Food Waste to Good Taste’ is an exciting campaign that we are running in partnership with @HKU_Science and @Green.Hospitality. The study will measure the nutritional value of food scraps from restaurants across Hong Kong to highlight the local food waste issue in two folds: from an environmental perspective and from a health perspective. The campaign hopes to encourage restaurants and consumers to be more conscious of the loss of nutritious food waste and optimise food scraps into new recipes to further reduce food waste.

If you are looking for an inexpensive and bioavailable source of calcium, then look no further than from your…eggshells! Easily accessible, zero-waste AND free (if you’re buying eggs already that is for your morning breakfast). All you need is a coffee grinder and your clean shells. 

Calcium is one of the most important minerals for our bodies. However, it’s difficult to attain the daily requirement goal if we don’t go out of our way to drink cups of milk, eat yoghurt or cheese constantly. Leafy greens and broccoli also contain calcium but them alone cannot act as a the only source of the mineral for our daily needs (plus you will need to eat A LOT of them). 

Eggshells are made almost entirely of calcium carbonate - similar to our bones, nails and teeth, and they are also packed with protein, magnesium and other compounds that are good for our health. Since DIY calcium powder is not a man-made supplement, consuming naturally grounded eggshells are even easier for our bodies to absorb them. It’s really a win-win solution to your empty eggshells. 

If you don’t usually eat a lot of eggs in one sitting, you can opt for stockpiling the shells over time. Since you will be sanitising your eggs before grinding into calcium powder, store your clean empty eggshells in a container in the fridge while you build up your stock. You can also freeze them until you have enough saved up.

Once you have made your own calcium powder, simply add half to one full teaspoon into anything of your choice to enjoy an extra boost of calcium. View the recipe below.

Eggshell Calcium Powder

This is probably the most versatile way to reuse your cooked pasta without much planning (or cooking!), yet highly effective in reducing waste. We have provided a recipe here to inspire you on your pasta salad adventure. But really, you can let your imagination run wild using whatever produce you have in your pantry/fridge. It's a great way to use up your tomatoes, cucumbers, herbs, or even carrots, potatoes, etc. you get the idea, the list can go on. Lastly, if you're looking for an easy salad dressing option, you can simply use olive oil et voilà!

Ingredients & supplies:

• 10-12 eggshells

• Medium saucepan or stock pot

• Baking sheet

• Coffee or spice grinder

Recipe:

• Once you have saved a dozen or so eggshells, rinse them thoroughly in water (remove any excess whites).

• Fill the saucepan or pot with water and bring to a boil.

• Place the shells into the boiling water for around 10 to 15 minutes to sterilise fully and to remove potential harmful pathogens.

• Drain the shells and spread them on a baking sheet.

• Bake for around 20 minutes at 110ºC/225ºF to dry the shells outs.

• In a coffee or spice grinder, grind the shells into a very fine powder 

  • NB: this recipe does not work as well with a normal blender as you will have larger eggshell pieces. The finer the powder, the better it can mix with drinks. 

• Finally, add ½ a teaspoon of your calcium powder to any drinks of your choice like smoothies or juice. This will bring about 400-500mg of calcium. Adjust to your daily requirements and needs (*keep to a maximum of 1 teaspoon of calcium powder a day). 

• You can also add the calcium powder into any broths or soups, bread dough or pizza dough for an extra calcium boost.