Question When to use or not use the "o-" prefix with food and drink items?

I'm a がいじん who is at a fairly basic beginner level regarding my learning of the Japanese language.

I have noticed that the words for some food and drink items can optionally accept an "o-" prefix, for example ...

すし -- おすし
さけ -- おさけ

However, words for other food and drink items do not accept this "o-" prefix, for example ...

たまご
ぎゅうにゅう

How can I, a foreigner learning Japanese, know which names of food/drink items can or cannot accept this "o-" prefix? Are there any rules for this, or is it just something that I have to memorize?

Also, for the items whose names can indeed accept the "o-" prefix, when would we normally use this prefix, and when would we normally not use this prefix?

よろしく おねがい します !

Hi and welcome to the forum.

In some cases, we use the "o-"
honorific to indicate who an item belongs to. For example, when referring to my beer and your beer, I might say, "obi-ru" when referring to your beer, but similarly only saying, "bi-ru" when referring to my own beer. (This has the added effect of eliminating the need to say, "my—" and "your—", because in some cases, saying 'your' and 'my' in Japanese can be a bit tricky.) In this way, a waitress asks, "Obi-ru desu ka?" to ask if you want a beer. (The idea is, your beer is 'honorable' whereas mine is not.)

Buntaro said:

Hi and welcome to the forum.

In some cases, we use the "o-"
honorific to indicate who an item belongs to. For example, when referring to my beer and your beer, I might say, "obi-ru" when referring to your beer, but similarly only saying, "bi-ru" when referring to my own beer. (This has the added effect of eliminating the need to say, "my—" and "your—", because in some cases, saying 'your' and 'my' in Japanese can be a bit tricky.) In this way, a waitress asks, "Obi-ru desu ka?" to ask if you want a beer. (The idea is, your beer is 'honorable' whereas mine is not.)

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That answered part of my question, and thank you very much!

But what about the other part of my question?

Some words for food and drink allow the "o-" prefix, and some don't. How can I, as a foreigner, know which words I can use "o-" with and which words I cannot use "o-" with?

For example, I know I can say "o-sashimi", but I can't ever say "o-tamago".

How can I know which words for food and drink I can use and cannot use the "o-" prefix with? Is there some sort of rule for that, or do I just have to memorize the group of food/drink words for which the "o-" prefix is allowed?

Don't get in the habit of saying おビール. In most situations it's not appropriate and it would sound odd. Here's a discussion on that very topic.

To answer your main question, you're just going to have to learn it by exposure and memorization which is the same way Japanese people learn it.
Eventually you'll learn which ones naturally take the "o." At least the common ones. (Also the honorific "go" such as "gohan").

Yeah, it's easy to get lost in the weeds when it comes to being polite in Japanese. I agree with @mdchachi that the best teacher is experience. There's no quick rule that I'm aware for words that can take o- versus those that don't.

Yes, it's indeed complicated. It's actually even not "your" vs. "my". For example, お粗末, お願い or お礼 are used for "my". These are categorized into humble expressions (謙譲語), not honorific (尊敬語). Also, おすし or お酒 can be used also for the speaker's one "my", for example 昨日おすしを食べた/お酒を飲んだ. These are called 美化語 (elegant speech). I, too, agree that you need to learn it from your experience.

Thank you to all of you, for all that you explained!

I was thinking that it's probably just a matter of experience, but I wanted to check here, in the off chance that there might have been some rule or system for deciding. Now that I see that this isn't the case, I'm glad to just go by experience.

And regarding おビール, a Japanese friend of mine recently told me the same thing that you (@mdchachi) wrote above: that it's hardly ever said that way. And thank you for the link to that discussion about this, which gives more detail. It's very helpful!

I now understand that the only "rule" (if that's even the appropriate word to use here) is that the お- prefix is hardly ever supposed to be used with foreign loan words. But that's only a rule about which words should not take that prefix. And again, I do indeed now understand that it's just a matter of experience to decide which non-loan words can and cannot take the prefix.

Thanks again to all of you!