Lemon juice soap

One of the soap groups on Facebook that I belong to does monthly soap challenges and this month they challenged people to make a soap using lemon juice. I thought that was such a fun idea, and something I’d never done either, that I wanted to give it a try myself and show you the process and results, so you can have a go at it yourself.

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One of the problems with using acids, like lemon juice, is that it will neutralise some of the lye in your recipe. The acid in lemons is citric acid, but the amount of citric acid varies between types of lemons as well as between the individual fruits themselves. So unless you’re a chemist with the right equipment, you can’t really know how much of the lye will be neutralised. If it’s too much, you’ll end up with a soft gloopy mixture because of the excess oils that didn’t get saponified (turned to soap). To make sure that doesn’t happen, you need to reduce your superfat or lye discount to a minimum. I reduced my superfat to 2%, and if I replace all the water in the lye solution with lemon juice I will get a soap with a superfat somewhere between 5% and 8%. Here’s the recipe I used:

Lemon juice soap recipe

  • 375 g olive oil
  • 25 g castor oil
  • 55 g caustic soda
  • 100 g lemon juice
  • 1 teaspoon sodium lactate
  • 15 ml lemon essential oil
  • annatto seed colourant

I pressed out three lemons to get 100 g of juice and placed it in the fridge to cool. Lemons not only contain citric acid, but also sugar, and I wanted to prevent the sugars from burning in the lye.

Once the lemon juice was cold, I carefully stirred in the caustic soda one teaspoon at a time, and check out the cool colour display I got! First it turned a bright yellow before going orange. To be on the safe side, I placed the jug in the sink with cold water to keep the lye from going too hot, and luckily it didn’t get any darker than that orange.

I continued normally using the cold process method: oils in one pot, and once the lye had cooled down, adding the lye to the oils and stirring. Because I knew from other soapers that the lemon fragrance from the juice would not come through in the soap, I added lemon essential oil to the soap,

I also decided to have a little fun with colour using annatto seed colourant, which I added to about 1/4 of the soap mixture. I then poured the colours into a bowl, alternating between the yellow and uncoloured soap, like you do in the ‘in-the-pot-swirl’ method. I gave the soap in the pot an extra swirl with my spatula and then poured it into the mold.

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I had no idea what the lemon juice would do to the colour of the soap and to the soap itself. I didn’t insulate it and despite it being in a cavity mold, the soap did go through a gelling phase. So a word of caution: don’t insulate and keep the soap cool! And despite the soap looking rather dark here in the mold and the next day when I unmolded them, they did turn a lovely white and yellow marble effect after a couple of days. And testing it after nearly a week already felt that it was going to be really pleasant mild soap!

For more information and ideas, check out this blog post about adding fresh ingredients to soap!

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Author: Jackie

Mum, blogger, soap maker, frequent flyer!

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