I see this question pop up a lot, and I get the confusion—the book's title is just 'Aphrodite' and it's not a novel in the traditional sense. It's actually a non-fiction, coffee-table style book by Isabel Allende, sort of an erotic scrapbook or memoir about food, senses, and love. So, there isn't a 'central character' in a plot-driven way. The central 'character,' if you have to name one, is the concept of Aphrodite herself, the goddess of love, or perhaps the embodiment of sensual experience.
Allende uses recipes, personal anecdotes, and historical tidbits to explore themes of passion, appetite, and the body. If you went in expecting a protagonist with a story arc, you'd be pretty thrown. I made that mistake myself once, picking it up thinking it was a mythological retelling. It's more like a guided, sensual tour through Allende's own perspectives and memories. The 'who' is really the reader's own senses being invited to the feast.