[Grammar] Plural or Singular form for fruit names

[Sugar Please]

I have a question regarding fruit names. When writing about fruit, I'm confused about which form I should use – singular or plural. I'm not even sure if they are actually count nouns or mass nouns or uncountable nouns.

Examples:

I heard banana is good for health.
Lychee, mango, and papaya are popular fruits in my country.
He could taste hints of kiwi fruit, orange, and apple in his drink.

Are the sentences above correct? If yes, why? Is it because they underlined words are uncountable nouns? Mass nouns? Material nouns?

I understand the common usage of the singular and plural form of say, the word, 'banana'.

I ate a banana for breakfast. (Banana - singular)
I ate two bananas for breakfast. (Bananas - plural)

I heard banana is good for health. (The "banana" in this sentence... is it a mass noun?)

I'm sorry if this is unclear. Please help.

 

[slevlife]

I heard banana is good for health.

Correct forms:
I heard bananas are good for your health.
I heard bananas are healthy.

Plural form is correct because you're not referring to a specific banana.

This is similar to: Motorcycles are cool.
You need to pluralize "motorcycle" for the same reason.

For whatever reason, using singular nouns with this sentence structure sounds more wrong with some words than others. For example, "papayas are healthy" is better than "papaya is healthy", but somehow "papaya is healthy" doesn't sound as bad as when using banana/orange/motorcycle in the same way.

Lychee, mango, and papaya are popular fruits in my country.

Use plural fruit names instead. For this specific sentence, the fruit names can use singular or plural and it won't really matter at least to American English speakers (for the reason I explained above: some words don't sound strange when used in this way). But with some nouns it would sound very strange. For example, "Apple and orange are popular fruits in my country" sounds unnatural.

He could taste hints of kiwi fruit, orange, and apple in his drink.

This is correct. That's because it's referring to the flavor of the fruits ("hints of ...") rather than the fruits themselves. But plurals would also sound okay here, and would imply that the flavors came from more than one of each fruit.

More details:

Even if you dropped the word "hints" and just said "He could taste orange, apple, etc. in his drink", you'd still be referring to the flavors rather than the fruits. Plural and singular forms would both continue to sound okay (and have very subtly different meanings).

If the fruits themselves were in his drink, you'd have to use singular and plural based on how many were in the drink. For example, if his drink contained two oranges and one apple, you'd say "There were oranges (pl) and an apple (sg) in his drink." If only pieces of the fruits were in his drink, you'd say, for example, "There were bits of orange and apple in his drink." Here only "bits" is plural. You could also say "There were bits of oranges and apples in his drink", but again this has the subtly different meaning that the bits were taken from multiple oranges and apples.

Note: none of this explanation is specific to fruit names.

 

[Glizdka]

Not a teacher
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As a rule of thumb, when talking about a whole fruit, it's countable. When it's processed in some way (chopped, ground, turned into pulp), it's uncountable.

 

[Sugar Please]

Thank you for your reply.

For example, "papayas are healthy" is better than "papaya is healthy", but somehow "papaya is healthy" doesn't sound as bad as when using banana/orange/motorcycle in the same way.

Why do you think using certain singular nouns would sound less wrong or acceptable instead of others? I guess I'm trying to find a grammar rule for this to understand it better.