Writing : Masticate Vs. Chew

Doesn't it have a certain animalistic, borderline gross feel to it? Maybe that's it? 

All this hate for 'masticate'. I don't know why, it's a perfectly cromulent word...

    Personally, I feel the only reason to use masticate would be for liyricism or because it humourously rhymes with another word.

And those are two good reasons to use a particular word, especially a particularly odd word like 'masticate'. But the only two? There are no other reasons to use a word? I'm going to have to disagree both in principle (we are after all using 'masticate' meta-lingually right now, a use that has nothing to do with it's lyrical or humorous value) and specifically for American Gods.

Redd is correct, context is always helpful:

From the heart, the liver, and from one of the kidneys, he cut an additional slice. These pieces he chewed, slowly, making them last, while he worked.

Somehow it seemed to Shadow a good thing for him to do: respectful, not obscene.

“So you want to stay here with us for a spell?” said Jacquel, masticating the slice of the girl’s heart.

That strikes me as another reason: Gaiman had just used 'chew' two sentences beforehand. And especially with the other repetitions that occur in this passage (I'd give him 'heart' because it's specific and visceral, and there aren't any good synonyms for it, but he probably could have found something else for 'slice') at the very least he probably should not use 'chew' again. And 'masticate' is a synonym for 'chew'.

Which seems to me a fourth (fifth?) reason: 'Masticate' is a word. It's not just a humorous or lyrical or pretentious version of 'chew' (that'd probably be something like 'choo', 'qi-ewe', or 'chü'). As Scrivner and Redd point out, it has a particular connotation. It is as different from 'chew' as 'gnaw', 'chomp', and 'nibble' are; in this case because it's a latinate word, it carries a formal/medical/scientific association. That gives it a whole slew of contexts that makes it not only permissible, but the preferred word and which, again, have nothing to do with its lyrical or potentially humorous value.

So, we now have at least four reasons to use 'masticate' instead of 'chew': lyricism, humor, avoiding repetition, and connotation. I'll grant that this particular example doesn't seem distinctly lyrical or humorous, and with all the other synonyms for chew available, avoiding repetition itself is probably not sufficient given how peculiar 'masticate' is, so whether or not this use of 'masticate' is appropriate hinges upon its connotation within the context. But we should keep in mind that if it turns out that Gaiman's use of 'masticate' is contextually inappropriate here, it doesn't mean it's pretentious. These four reasons are also hardly exhaustive of all the modes or purposes of use for a word like 'masticate' (there is also the phatic, imperative... already mentioned meta-lingual...)

But let's first establish in/appropriateness in context: does this qualify as a formal/scientific/medical context to use a word like 'masticate'? In my estimation, it does. On a few different levels:

First, Jacquel is one of the most formal characters in the novel, along with Mr. Ibis, they are the most "refined", "proper", and "sophisticated" characters. If anyone in this book would 'masticate' it would be Jacquel, and as far as I know, this is the only instance of the word (which is actually quite remarkable considering how much eating takes place in this novel; how the gods obtain sustenance is one of the major themes in the book and nearly every major plot point occurs with a meal), but it is a somewhat weak affirmation: just because a character is formal does not mean everything they do is formal or should be referred to formally (and you'll recall, two sentences earlier, wasn't.)

Second, this is a medical setting. They are morticians, Jacquel is performing a medical procedure on a body. Now, I can see some disagreement on this point. It certainly isn't standard in modern settings for a mortician to consume parts of the deceased, so on the surface this can be seen as at least tangential to the procedure that grants the context, if not simply eccentric. But I maintain, this is only a superficial interpretation of what is going on in this scene. This is probably the first explicit indication that these are not your average morticians, but I don't think that means we can simply gloss over the implications of this action. For Jacquel, this is as much a part of the procedure as anything else done to prepare the body. And as we observe this short passage, Shadow comes to realize this as well. The change in language itself indicates as much: Jacquel chews the slices, Shadow sees it as a good thing to do, respectful (here the turn for him, his realization) and in the very next line, 'chew' has become 'masticate'. And this is probably the strongest case for it as it not only grounds the word in the context of the character performing the action, and the medical nature of the action itself, but also within the perspective of the character whose point of view we are seeing this story through.

And third, even outside the explicit medical setting, the action itself is scientific (or at the very least empirical.) This, however, treads a bit into spoiler territory, and I don't want to presume you've gotten to the part of the story that this scene foreshadows. But at the same time, it's not as if Gaiman is hiding what is going on. Wednesday? Mr. Ibis? Jacquel? He is not being subtle. He's not lauding anything over the reader's head. It only escapes the protagonist because he's definitively passive (Shadow?) and if we as readers aren't as informed about our mythology, we aren't punished for it. It all comes out later as it becomes pertinent to the plot.

Now, you can certainly disagree with my interpretation, and maintain that even with its connotations and context 'masticate' is too weird a word to use in this passage. Or even disagree in principle that contextual or stylistic reasons are not sufficient causes for word choice (though you should probably stick to poetry if that's your intention, where lyricism and evocation are the primary modes of communication) but even then, you should at least account for them, especially before levying attacks of pretentiousness. Otherwise, it just seems like an affectation of critical thought or objectivity that wasn't actually applied to the passage.

Personally, as I'm sure you can tell, whether or not I would use 'masticate' or 'chew' depends entirely on what I feel is the best word for the story I'm writing, so I can't really make blanket statements as to whether I would use one or the other outside of that context. In this example passage from American Gods, I would've used neither, because of stylistic choices and not vocabulary. I am much more sparing in my use of dialogue tags than Gaiman is. I'm not sure I would've seen that line of dialogue as an opportunity to show the change in context and perspective as he has it, and probably would have left it unadorned, or at most: "said Jacquel."