How to prevent carrot juice from turning brown?
I've been juicing up carrots with a centrifugal juice extractor. There's a lot of overhead (prep and cleanup) so it makes sense to do a big batch and keep it in the fridge for a couple of days.
Unfortunately, the refrigerated juice seems to turn brown pretty quickly. Here it is after 48 hours:
The pulp has precipitated to the bottom and retains its pleasant orange hue, but the juice has turned an ugly and unappetizing brown. It tastes better than it looks, but the flavor has suffered too. It's pretty extreme at 48 hours, but there is significant browning even at 24.
I'm using refrigerated carrots and putting the juice immediately in a plastic screw-top (Ziploc) container in the fridge.
Is there anything I can do to keep my carrot juice looking and tasting fresh?
Best Answer
This is classic enzymatic-oxidation browning. Two main culprits - oxygen and a group of enzymes (polyphenoloxidases) that promotes a reaction between oxygen and polyphenolic compounds in the juice.
The juicing action will inevitably end up stirring into the liquid a lot of air which will end up dissolved in it. Air has 21% oxygen in it. Solubility of gases improves with lower temperatures. So, cold juice will hold more oxygen, and warm juice less. Unless you do your juicing inside a sealed cupboard filled with nitrogen, you will not be able to exclude oxygen from getting inside your juice. At lower temperatures, the enzymes become less active which will slow down the browning and counter the higher concentration of oxygen in your juice, but given enough hours, browning will still happen. You can try putting a barrier on the surface of the juice (a sheet of parchment or plastic for example) as soon as you finish juicing and before you put it in the fridge to prevent more oxygen from dissolving into the juice as it chills. It is unlikely to stop the browning.
You can restrain the enzymes by making the juice more acidic, with lemon juice for example, or vitamin C as suggested above (the key is pH not how much Vitamin C it naturally has) or citric acid. That would only slow down the browning and you might not like the altered taste.
You can deactivate the enzyme permanently by heat which means heating the juice to at least 65C, or better still, heating the carrots before juicing to well beyond 65C briefly. I suggest cutting the carrots into smaller pieces and putting them into a very hot water with any of the above acidic additives. I am sure heating will inevitably affect the taste, but it will stop the browning. It works with apples and pears. You can play with timing so that you destroy a certain amount of the enzymes, enough to have a good compromise between less browning and less taste change.
There are suggestions you find online such as freezing. You can freeze your juice, but again it would only slow down the browning a bit more, it will still happen given enough hours.
Other more extreme (and normally impractical) ideas include vacuuming the juice to extract dissolved gases from it, or using UHT and high pressure methods to break the enzyme.
I typically use 65C acidic water to blanche whatever fruit or vegetable, and I use a barrier on the juice surface before storing/chilling.
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Quick Answer about "How to prevent carrot juice from turning brown?"
You can deactivate the enzyme permanently by heat which means heating the juice to at least 65C, or better still, heating the carrots before juicing to well beyond 65C briefly.How do you keep carrot juice from oxidizing?
Making the Most of Your JuiceHow do you preserve carrot juice?
The shelf life for all fresh homemade carrot juice is roughly 48 hours if refrigerated in a sealed container or juice jar. If you plan to store your carrot juice up to the 48 hour marker, then it's a very good idea to stir into it a heaping tablespoon or two of fresh squeezed lemon or lime juice.How do you keep carrots from browning?
Carrots. Fresh cut carrots can be kept in plastic bags in the refrigerator, but to prevent them from drying out, either wrap them in moist paper towels or store in cold water. Loosely cover the water to ensure no debris gets into the water, but don't use an airtight container.How long can I preserve carrot juice?
Carrot juice that has been continuously refrigerated will keep for about 7 to 10 days after opening. To further extend the shelf life of opened carrot juice, freeze it: to freeze carrot juice, store in airtight container and leave at least 1/2 inch headspace at the top, as carrot juice will expand when frozen.8 Negative Side Effect Of Carrots That You Should Be Aware Of
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Answer 2
juicing up carrots with a centrifugal juice extractor
This is very common for centrifugal juice extractors and one of the reasons why the juicers crowd prefers masticating juicers. Of course, the solution is not practical for everyone, and it does not completely prevent this type of browning and separation, but it does slow down.
Answer 3
Based on Paparazzi's comment, I'd store it in a cleaned wine bottle and use a stopper/air-remover like a vacu-vin. That's a brilliant comment.
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