Unlike other orange chocolates this week, the citrus flavor was infused into this bar using a "proprietary method," presumably during the curing process. That is, the three-ingredient list for this bar read: "cacao, pure cane sugar and cacao butter"—but no orange. How is that possible?
More chocolate makers are experimenting with different ways to infuse natural flavors into their chocolates in recent years; for example, they may barrel-aged their cacao nibs, or expose chocolate to flavors during fermentation or aging.*
Just as foods can be stored in a smokehouse and pick up a BBQ flavor, they may also pick up more subtle flavor nuances if stored with certain substances or exposed to vapors or volatiles in a confined area for a period of time.
*Once a batch of chocolate is made, blocks of chocolate may sit on a shelf (covered, in a cool storage area away from direct sunshine) for a period of curing, before bars are tempered and packaged into final bars for sale.