I like books with single topics -- though they always turn out to be about more than one thing. Some of my favorites (surprise, surprise) are about food, at least ostensibly.
Salt: A World History by Mark Kulansky is, not surprisingly, about, yes, salt. For those of us from upstate, we know salt is important --hence the salt city (it is Syracuse's nickname), salt potatoes, and there are major salt deposits near both Seneca and Cayuga lakes (hence the Watkins Glen refinery of US Salt and Cargill Inc.). On my shelf, I have sea salt from France, black and red salt (both coarse and fine) from Hawaii, Himalayan pink salt, and Hibiscus salt (which is a lovely purple-ish color). Not to mention my usual Morton's and some kosher salt in the pantry. Salt -- not just one thing -- from mines, from desalination plants, skimmed from the surface of brackish water. (I have only seem this in the Caribbean, but hey, it is a time honored way of getting salt.)
Curry: A Tale of Cooks and Conquerors by Lizzie Collingham is another like offering. Of course, we all know that curry is more than one thing -- despite its marketing in little bottles and big bags as "hot curry powder" or "curry powder" or. . . . red (or green or yellow) curry paste. This is a great book that reveals loads about the complex history of India (and its environs) -- across centuries -- and miles and miles of a huge geography. How did we end up with "curry" and its many meanings? (Who do we mean by we?) Read the book. I particularly like the chapter on the introduction of tea drinking to India. And, I learned an immense amount from the ways various cultures have influenced India, including the arrival of hot peppers of various degrees of heat via various circuitous routes (originating, of course, in the Western hemisphere). If you need more persuading, check out this review ages ago in the NY Times.
But what am I reading now? A much slower read, alas. Nathaniel's Nutmeg: Or the True and Incredible Adventures of the Spice Trader Who Changed History (also known as Nathaniel's Nutmeg: How One Man's Courage Changed the Course of History) by Giles Milton is a semi-swashbuckling recounting of Dutch and British colonialism -- efforts to get to the "spiceries" via the Arctic, accounts of boats which set off and most died before arriving in the Banta Islands -- from scurvy and dysentery and. . . . of men killing each other. Accounts of small islands with monopolies on nutmeg -- selling for a penny what sold in London for 50 shillings. Stories of the Dutch and the Portuguese and the British -- and, less directly, the people who lived on these islands. Nutmeg, mace, cloves. Plague treatments, high class spices. I don't use nutmeg much -- though I love it on eggnog and of course in some baked goods. This book, unlike Salt and Curry isn't really about the food item in the title -- nutmeg. Though it does remind us (as do both the other books in somewhat more appetizing ways, which may not actually be for the better) of the entanglement of food and spices with the less desireable traits of humanity like colonialism and imperialism, capitalism through invasion and genocide, environmental destruction and war. Certainly, the book reminds us of the downside of certain forms of historically valued masculinity in the west. Not to mention, the global reach of history. I won't reveal the punchline of Milton's book -- but even nutmeg (and the spiceries) relates to the Finger Lakes (or at least New York).
So: single topics worthy of obsession. Food for thought?