Help me understand sterilising glass bottles for cordial

December 15, 2022 2:26 AM

I am planning to make lemon and mint cordial and am finding conflicting information regarding sterilisation of the bottles. Some sites say it is OK to just wash them in hot soapy water, some say I must boil them, others say I should put them in the oven... So what is really necessary? I plan to consume the cordial within a month - not sure if that makes a difference? I don't have a pot big enough to boil the bottles on the stove so hoping I can get away with something else but also don't want to put anyone at risk!

So my two questions are: what is the best practice for sterilising glass bottles and does it make a difference that I only plan to keep the cordial for max a month?

posted by toebeans to Food & Drink (14 answers total)

How are these bottles going to be sealed?
posted by flabdablet at 3:47 AM on December 15, 2022

I would say that if you're giving them away, you should do the absolute most you can do. I personally make jam more so than cordial, and I boil things first - but that's part of the canning process anyway so I have a big enough pot. Some people also suggest baking the bottles for a while.

It also makes a difference what you do AFTER you sterilize them, and how soon you use them. If you wash them really well in hot soapy water and rinse them out and then immediately after that you pour in the cordial, that is probably fine, because there is a much lower amount of time for any possible contaminant in the air to get into the bottle. But if you wash them really well and then they just sit on the counter for a couple hours, and THEN you pour the cordial in, that's given them a couple hours to get contaminated by whatever microbes might be hanging around in your kitchen.

So: since you don't have a pot big enough to boil them, I would do one of the following:

1. Bake them in an oven. This discussion on a home brewer's forum has good advice for that; they even have advice about how to keep things sterilized for a good while after you bake them, so you can get away without pouring the cordial in right away.

2. Run them through a dishwasher at the highest possible setting.

3. Wash them really well with A LOT of hot soapy water, rinse them out really well with hot water, and then IMMEDIATELY pour in the cordial and seal.
posted by EmpressCallipygos at 4:39 AM on December 15, 2022 [1 favorite]

None of the methods you described will sterilize your bottles, but that's ok because you don't need to. Nothing related to food needs to be sterilized. You may need to sanitize the bottles; it's probably good practice especially if you're handing them out as a gift, but given that cordial has a lot of stuff in it that makes it inhospitable to the kind of bugs that make you sick (sugar and acid are both preservatives), this would be to have them stay tasting good as long as possible.

Home brewers of beer will sanitize before bottling. The methods I'm aware of/have used in the past include:
-Sanitize cycle in a dishwasher (no detergent or rinse aid). "Very hot" setting is not hot enough to sanitize.
-Dip bottles in an iodine solution (Iodophor is a common brand) - soak for the recommended time, drain, and dry. Do not rinse.
-Use an acid-based sanitizing solution such as Star San - same concept as Iodophor, no rinse.

Heating bottles dry in an oven is just asking for them to shatter from thermal shock, I would not do that. Hot soapy water is not sufficient to effectively sanitize.
posted by backseatpilot at 4:49 AM on December 15, 2022 [5 favorites]

Heating bottles dry in an oven is just asking for them to shatter from thermal shock

Putting a cold bottle on a hot oven rack is asking for trouble. But if you've got a fan-forced oven, and you rack the bottles when it's cold and then turn on the heat and the fan and let the bottles warm as the oven does, and at the end of the cycle you leave the fan running with the heat off and let them cool as the oven does as well, I think they'd heat and cool evenly and therefore without stress.

If the bottle mouths are wrapped in foil before they go in, the insides should stay sterile pretty much indefinitely afterwards.

Baking bottles with inbuilt rubber seals would degrade the seals, which is why I asked about sealing.
posted by flabdablet at 5:13 AM on December 15, 2022 [1 favorite]

I've made cordials with alcohol and have not sterilized the recycled bottles; they were fine. I just use bottles I'd washed at some point. To be more cautious, I would probably use a dishwasher because dishwasher detergent is strong, and I'd use the heat drying cycle to get them quite dry. Cap them when you take them out of the dishwasher until you use them.

Sugar is a preservative, alcohol is a preservative, enjoy your cordials.
posted by theora55 at 6:38 AM on December 15, 2022 [3 favorites]

Note that depending on the shape of your bottles, the interior might not get well cleaned in a dishwasher if a narrow mouth or neck limits water from spraying in.
posted by nouvelle-personne at 6:38 AM on December 15, 2022

I'm wondering if some of the conflicting advice you've seen online could be different definitions of cordial? I've seen the word used for both alcoholic drinks and non-alchoholic. We make a (pretty strong) liqueur that we call a cordial and just wash the bottles. We've never had a problem and give them as gifts, but maybe we'll rethink some.
posted by Press Butt.on to Check at 6:57 AM on December 15, 2022 [3 favorites]

You can contact your local extension service (typically within the nearest agriculture school to you), give them the recipe and ask if you need to sterilize, sanitize or wash the bottles.

Without the recipe, it’s not super easy to tell what may be needed, but I agree with the folks above, i would probably rely on a soak in some Star San and call it good. Star San or other sanitizer is going to get you more reliable results than baking or regular soap washing.
posted by furnace.heart at 6:58 AM on December 15, 2022 [3 favorites]

Like others have said, I don't know what you're making, but I can say that if it turns out you need to put the bottles in hot, boiling water on the stove, you don't have to put all the bottles in at once. You can put one or two at a time in a standard-size pot (again, depending on what size bottles you're using). If you've got a stove-top-safe roasting pan, you can use that and get in a few more. It just takes a bit more time and you have to leave yourself room for putting the full jar/bottle back into the water.
posted by sardonyx at 7:05 AM on December 15, 2022

I would get some StarSan and use it to sanitize the just-washed bottles, as backseatpilot says. Then put your cordial in there and cap them up.

That's what I do with my mead, and it hasn't sickened me yet!
posted by wenestvedt at 7:29 AM on December 15, 2022

If this is a strong alcoholic cordial, the sterilization is way less important (I make cordial and eggnog and liqueurs, and I just use clean mason jars out of the dishwasher)

But I also make wine and in that case I wash the clean bottles again in hot soapy water, rinse them, and then they get a dip in starsan and are filled and corked right away! (starsan is very cheap and easy to use!)
posted by euphoria066 at 7:33 AM on December 15, 2022 [2 favorites]

Long time homebrewer. Came to say what backseatpilot already said well.
posted by terrapin at 8:45 AM on December 15, 2022 [1 favorite]

I don't have much experience with sterilyzing either, but I am interested in mushroom cultivation, and they suggest sterilyzing jars in a pressure cooker (for example, an instapot) which might produce better results than an oven or boiling alone.
posted by Perko at 12:57 PM on December 15, 2022 [1 favorite]

When I've made alcohol based infusions with higher sugar content/high alcohol content like nocino I've had good luck just washing things in the dishwasher. The combination of alcohol and sugar tend to inhibit bacterial activity, but these are also at around 45-50%abv, this might not work as well with lower proof stuff. If that's the case I follow with the recommendations of everyone else here that using starsan as a sanitizer is your best bet. Way less likely to leave a funky taste than bleach or iodine based sanitizers.
posted by Ferreous at 8:37 AM on December 16, 2022