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I found this recipe which features Italian meringue as topping. After preparation, the meringue is not cooked further, yet the author claims that adding the sugar syrup alones has pasteurized (i.e. killed all germs) the eggs. Can this really be assumed?

The basic steps in this recipe in this regard are:

  1. Beat 100g of egg whites until stiff
  2. Add 200g of sugar, dissolved in 30g of water and heated to 120°C

Assuming that the 100g of egg is at room temperature, or slightly cooler, then the mixture would probably exceed 70°C, but I am concerned that the time it would be this hot would be long enough to actually consider the final product pasteurized.

Glorfindel
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FlyingTeller
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    I imagine you'd primarily be concerned about salmonella and listeria in eggs? I have to think that the relatively low water activity of something with such a high ratio of sugar to water is also protective. It might not kill any pathogens present, but it would prevent them from multiplying. – Matt Morgan Feb 12 '24 at 21:07

4 Answers4

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For the pasteurization of egg whites, the time required is at most 48 seconds at 140 F (60 C). (Source: FSIS, table on page 39)

This means that you can easily use the method to know if you've pasteurized the egg whites. Simply keep the thermometer in the bowl while beating your meringue. If it takes more than 48 seconds to fall under 60 C, you've pasteurized them. And if you should find out that it fails too often, you can change your setup - e.g. start beating the meringue over a water bath - to ensure you reach the required duration. In practice, I think that it would be difficult for you to make a meringue that cools down in less than 48 seconds.

Note that this requirement is for egg whites specifically! The times for whole eggs and egg yolks is given in the same source, in a chart on page 17, and they need more time for pasteurization.

Glorfindel
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rumtscho
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    Looking at that table, it seems that if it is above 62C for more than 17 seconds it would be fine, so extra heating would probably not be required assuming the introduction of the hot sugar syrup will bring the temperature above 62C. Which I would expect it to do as the sugar will be between 118 and 120 when it enters. In other words if it is over 62C then you need 1/3 the time as you would at 60C, which gives a much wider margin of safety. – Justinw Feb 13 '24 at 15:26
  • @Justinw the sugar syrup in Italian meringue is heated to soft ball stage (about 114°C) and then added slowly to the mixer over the course of about 30 seconds to 1 minute. So it won't be quite as hot as you are suggesting, but should still be plenty hot enough to kill any pathogens almost instantly. – Z4-tier Feb 13 '24 at 23:54
  • @Z4-tier My point was less about the sugar temp, as it was that if you are expecting the mixture to heat to over 60C with the inclusion of the sugar, it is a very reasonable assumption that it will be over 62C anyway. Which means that the temp/time window for it to be "safe" without extra heating was larger than what the answer implies. (Also the recipe in the OP specifically calls out heating the sugar syrup to 118-120, which would be more in the firm ball stage if I am remembering my sugar stages correctly) – Justinw Feb 15 '24 at 09:00
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I would not consider this "pasteurization," which has a specific meaning in food science, but the method of "cooking" sugar to around 240°F or 116°C and threading it into an egg foam is an accepted and proved method of ensuring the food safety in your meringue. You do not need to check the temperature, but you can feel the mixing bowl (especially if it's metal) and you'll get an idea of how hot it is and how long it takes to cool to room temp.

As a side note, I would not employ the method you state exactly. I find it's best to use about 1/3 of the sugar uncooked and add it to the eggs (French meringue-style) after it has reached soft peaks (or at least a decent foam, depending on your sugar grain size) and then beat the whites to a a medium peak before threading in your sugar. There are many methods that work well, so if the recipe you're following works for you then that's great as well.

You can also add an acid (like cream of tartar) to the whites before beating them which helps prevent the proteins from bonding too tightly and also helps the foam form.

If you're very concerned with food safety another method you can use is the Swiss method where you cook the egg whites and sugar over a double-boiler first (to 160°F or 70°C) and then beat them in your stand mixer with the whisk. I prefer the Italian method, but this works well and is easier to do.

myklbykl
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  • Why do you add 1/3 of the sugar unheated? What benefit does it give over adding it all as syrup? – Z4-tier Feb 13 '24 at 23:53
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    I have made meringue both ways. By adding some of the sugar earlier it helps stabilize the foam and you get a better, more stable, shinier meringue than cooking all the sugar and adding it to the eggs that way. Acid will also help stabilize the foam as mentioned, so this will also help if you want to cook all the sugar. I never both with acid myself, but I do prefer the French/Italian method. I teach baking and food science, and I have made a lot of meringue. – myklbykl Feb 14 '24 at 05:21
  • "I never both with acid myself" should be "I never bother with acid myself." – myklbykl Feb 15 '24 at 17:43
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Jurisdiction disclaimer: If you are in the US raw egg whites are not considered food save and may not be served in a commercial setting. Whether you want to personally take the risk is up to you.

If you are in Europe, raw beaten egg whites are used in some recipes and are considered food save. A common example is a mousse au chocolat. Of course one should only do that with very fresh eggs from a reputable source and possibly avoid recipes like that if you are in a risk group like being pregnant.

I don't know whether the difference is due to the US having stricter standards on food safety or due to Europe have stricter standards on producing and selling eggs. If you are somewhere else in the world, check your local health authorities.

quarague
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    Which is exactly why raw egg mousse au chocolat is not considered generally safe, but an acceptable risk for non-vulnerable groups. Or bluntly, those that may end up with diarrhea that they will likely survive. So raw meat (think steak tartare), raw egg (your aforementioned mousse) and raw milk are examples of foods where food safety related risks can be limited by proper preparation and handling, but not excluded. It’s up to the consumer whether they are willing to take the risk or not. – Stephie Feb 14 '24 at 09:21
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    @Stephie This may be jurisdiction dependent but in Germany you can get dishes like steak tartare or a chocolat mousse in restaurants. So they are considered save enough to satisfy the official health standards. This is not something where the customer is taking a risk or not, it is just officially save food (assuming the restaurant is doing things the way they are supposed to). – quarague Feb 14 '24 at 10:04
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    The UK in particular are quite proud of their “lion eggs” (standard for grocery eggs), which they promise are safe to eat raw even for vulnerable groups. – Sneftel Feb 14 '24 at 11:00
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Harmful microbes are not your only concern. Raw egg whites contain protein named avidin, which is an antinutrient that severely interferes with vitamin B7 absorption. Prolonged consumption could cause vitamin B7 deficiency. Avidin is quite heat resistant and remains stable below 70 °C. Just mixing raw egg whites with melted sugar is not going to destroy that protein.

More from Wikipedia:

A 1991 assay for the Journal of Food Science detected substantial avidin activity in cooked egg white: "mean residual avidin activity in fried, poached and boiled (2 min) egg white was 33, 71 and 40% of the activity in raw egg white." The assay surmised that cooking times were not sufficient to adequately heat all cold spot areas within the egg white. Complete inactivation of avidin's biotin binding capacity required boiling for over 4 minutes.

user108249
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  • I don't believe the presence of avidin in egg whites poses a significant dietary concern. In Italian meringue the whites are heated to a temperature above avadin's denaturation point and also one would need to eat a relatively high amounts of raw egg whites to impact biotin status. However, if there is original research that shows otherwise, I'd love to see it. Because Italian meringue is subject to many variables, the peak temperature of the egg foam will vary, but I'd also love to see any data showing average temperatures and slope. – myklbykl Feb 15 '24 at 03:24
  • How much raw egg does one need to consume to cause a vitamin deficiency, and over what period of time? Besides, this is a dessert not bodybuilding supplement. – Luciano Feb 15 '24 at 10:58