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How to preserve green color of green tea used in cleanser formula?
I’ve been formulating a cleanser that uses fresh green powdered sencha, both for the antioxidants and for the color. But it turns from a beautiful green to brown over the course of a week or two. Are there any other antioxidants or chelators one could add to preserve the color? EDTA? Citric Acid? The formula has been adjusted to pH 4 with lactic acid.
Ingredients: Distilled Water, Camellia Sinensis (Green Tea), Sodium Cocoamphoacetate, Decyl Polyglucoside, Willow Bark Extract, Lactic Acid, Sodium Lactate, Vegetable Glycerin, Camellia Sinensis Leaf Extract, Panthenol, Phenoxyethanol (and) Caprylyl Glycol (and) Sorbic Acid, Allantoin, Xanthan Gum -
19 Replies
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For antioxidants, BHA/BHT are still preferred chemically. For natural products, not so much…Tocopherol is probably your best bet for a natural antioxidantFor chelating agents, EDTA and EDTA salts are still preferred chemically. For natural products, also not so much…Try:- Sodium phytate/Phytic Acid
- Itaconix DSP 2K -
my guess is that it’s related to the tannins in your green tea, which go brown/black in the presence of iron; the first thing I’d try would be adding a chelator
in addition to the chelators Bob mentioned, I’d recommend Dissolvine GL from Akzo Nobel (INCI: Tetrasodium Glutamate Diacetate) if you want a biodegradable naturally derived alternative to EDTA
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Thanks, potentially very useful input, for starters I will try (a combination of):
Citric AcidDisodium EDTAGlucono Delta Lactone (GDL) -
Anyway, don’t forget to put a disclaimer in your label. Something like “due natural ingredients color variations can occur”.
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I would use sodium metabisulfite here at 0.10%.at that pH level, it ought to do the trick. Cheap too.
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Thanks, I will test sodium metabisulfite as well against the others.
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I made the following samples, only citric acid changed pH, reducing it from 4 to 3.6. From left to right:
#1 Citric Acid 1%
#2 Disodium EDTA 0.5%
#3 Sodium Metabisulfite 0.5% (Percentage taken from CC discussion)
#4 Glucono Delta Lactone (GDL) 1%
#5 All of the above
#6 Control
Only Sodium Metabisulfite is making a difference. As you can tell, I also have a consistency problem, the liquid is not homogenous, number #3:
Things to try:1. Remove green tea powder from formula
2. Change the thickening agent (suggestions?)
3. Setup two hours of slow stirring to better blend the formula (Xanthan Gum, clear, takes a while to clarify).Other ideas?
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Would you consider sodium ascorbate? It is especially effective at stopping the browning reaction of plant extracts and vitamin C is naturally good for people.
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BTW I am coming from an Immunodiagnostics background with plants. I am new to cosmetic chemistry.
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Assuming the green colour is chlorophyll derived from the tea, the usual way of stabilisation is to form the copper-chlorophyllin complex.
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Green tea is an indicator. The colour will depend on the pH. For instance, at a use level of 0.2% (dried tea extract) in a hand cream, we get green-brown initially (pH basic) then pink when adjusted to pH = 5.5, then after some time it turns to a tan colour (oxidation I assume).
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Have you tried using sodium copper chlorophyllin? (As a deodorant, of course, because using it as a colorant would be contrary to FDA regs)
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@wbliss wouldn’t that make the formula more unstable by having to deal with ascorbic acid-in-water oxidation? Otherwise I like the idea.
@johnb do you have any good methods or are you saying google it?@Bobzchemist I had some at one point, but seems like it’s cost prohibitive or do you know any good sources?
BTW Sodium Metabisulfite still does the trick, but the sulfur gives it a sharp and undesirable scent that must be masked.
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Sodium copper chlorophyllin gives a very intense green color (purely as a side effect, you understand). To tint your gel green would require 0.005% or less. It’s expensive in bulk, true, but a little goes a long, long way.
It’s good bug food, though, so I’d strongly suggest adding it as a 1% solution in ethyl alcohol.
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@Bobzchemist thanks, very useful info, might revisit it, could potentially help with ensuring long term green-ness.
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If you need a little to play with, let me know.
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No worries, it’s available on ebay at all places, 5 g for $15 incl shipping. Going to see how much I need to use for it to make a difference.
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You may try to adjust pH in the range: 5.5 - 6.5 in a Lab Batch, hopefully, the green color will stay for a while
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