"All of them are very delicious."
For me, the expression 'very delicious' is problematic, whereas 'absolutely delicious' or 'very tasty' are not. There is a distinction in English, and in Japanese also for that matter, between adjectives that are gradable (that can be modified by very, etc.) and ones that are ungradable. This is why we can say 'absolutely fantastic / awful' and 'very good / bad,' but not 'very fantastic / awful' and 'absolutely good / bad.' There is regional and personal variation as to which words are considered gradable, so the word 'delicious' is gradable for some, but not for myself and many others. おいしい in Japanese and 'tasty' in English, on the other hand, are both gradable. There is further variation in their use in comparatives.
Here are a couple of links:
Interesting read, although I guess I fall into the camp of everything being gradable (depending on which grading word I suppose - some don't make sense). Right off the bat, "very fantastic" sounds weird, but "thats mostly fantastic news" would be a good description for someone who broke their leg but had a successful baby delivery. Certainly other ways to say it, but I wouldn't bat an eye at that. Then "absolutely good" is literally in the Christian definition of God.
My favorite though is the "very dead" which I've actually used fairly recently - as an example, you've got "zombie dead" and "dead dead". Someone in the game dies, "yeah, they're dead." But they come back as a zombie, so you shoot them with a rocket "oh yeah, now they're very dead." Or in any general use of "wow, yeah, hes very dead... Don't think you needed to run him over with your car, after you chopped his head off, after you lit him on fire, after you shot him 10 times" - generally being an expression of overkill.
I have read in the other comments that 全部(ぜんぶ) is an adverb. Initially I could not really find to terms with it. However, if one reads it as "collectively", an adverb indeed, it makes sense. "Ad a whole" is also a passable translation, insofar it makes perceive the lack of a particle as less awkward