Gifford’s comment “Legendary (and quasi-cynical) explanation for the survival of missionaries”, misses the historico-factual component of Bloom’s unappetising musings.
The story that white man’s flesh tasted of salt (and tobacco) is recounted as early as 1859, in the Diary of a Working Clergyman in Australia and Tasmania (p. 170). The following episode occurred in Australia, and was picked up widely by the newspapers:1
Jan. 15  […] This is the first time I could ever get a confession of cannibalism out of a native. I have been told that the blacks cannot endure a white man's flesh. They say that it tastes very salty, and is highly flavoured with tobacco.
Before that, accounts not involving whites suggest that lemon juice and salt were added to human flesh to make it more palatable:
When mortally wounded, they run up to him as if in a transport of passion, cut pieces from the body with their knives, - dip them in a dish of salt, lemon-juice, and red pepper, - slightly broil them over a fire prepared for the purpose, - and swallow the morsels with a degree of savage enthusiasm.
Evangelism Magazine and Missionary Chronicle (1814), vol. 22 p. 433, citing William Marsden’s History of Sumatra (1783, p. 302)
At least from the 1870s – when Bloom was a little boy – newspapers had regularly focused on the lives of cannibal tribes in various exotic locations and provided delightful shivers for their deliciously appalled readership. The tribes reported by the papers typically came from Fiji:
The religion of the natives is mainly controlled by public policy. Their present Chief was formerly a cannibal. When converted he had 11,000 followers. The human-flesh-eating chiefs are known as "Butchers". Cannibalism still exists to an alarming extent throughout the interior of Vitelene, an island 90 by 60 miles in extent. Annual feasts are given to such Chiefs as have slain foes in battle and performed deeds of daring. At these disgusting carnivals the bodies of native boys of twelve to fourteen years of age only are eaten. From earliest childhood these subjects are fattened for the horrid feast. […] The native boy flesh is for the palates of the Chiefs only. That of the white man is considered too salty and smoky, and is not regarded as toothsome. Captain Fuller informs us that there are over 100,000 cannibals on the island, and only last August two Scotchmen were captured and eaten by the natives.
San Francisco Alta, cited in "The Fiji Island Cannibals", in New York Times (1871) 24 November
The salty missionary turns up in this report of 1887-8:2
Mr. Snow called a congress of these ex-cannibals, and they told him of their former ways of living, killing their enemies and afterwards eating them; all of which we will omit, except this: That white men and sliced missionary were too salty for their taste.
Joseph Savage "The Pink and White Terraces of New Zealand" in Transactions of the Annual Meetings of the Kansas Academy of Science (1887-8), vol.11, p. 28
An article of 1889 with the headline “Among the Man-Eaters of North Queensland” describes at great length the saltiness of the white man:
Many of the men are physically fine fellows, and some of the women have pleasing features. Then, when you call them cannibals you must remember that human flesh is a very rare luxury, for they only eat foreign tribes. Native tribes, I mean, for the flesh of the white man is nasty to their palate. He has a salty flavour, which is very disagreeable to them. […]
THE CHOICEST PARTS OF MAN.
[…] I never saw a cannibal feast, but every night in their huts the talk was of women and human flesh. Those were the stock subjects of conversation […] I was able to understand them,[…] and I gathered that white man was no good – too salty. Chinaman was not half bad. He fed on rice and had a tender vegetable flavour about him, like a mealy cauliflower. But of all varieties there was nothing so sweet as a native baby – so sweet, so juicy, so fat so tender.
Pall Mall Gazette (1889), 10 Sept.
Except for Bloom’s insinuation about what the “parts of honour” were we have come across all the elements of his musings already.
The part of honour for the cannibals was usually the kidney and the surrounding fat,3 but Bloom may have picked up and fantasised about information like this:
The boy used to hunt people just as we are hunting for deer. He took the bodies home to the old man, who ate the testicles of all the men the boy killed.
Memoirs of the American Folklore Society (1917), vol. 11, p. 173
By 1921 the Chicago Journal was prepared to face down these myths:
The country boy might tell the near-savant that the yarn of Fijians refusing to devour salty missionary [sic] is on all fours with the Western story that coyotes will not eat a Mexican, because he uses so much chili sauce.
Chicago Journal, cited in Washington Post (1921), 21 May, p. M2