It has been discovered that irradiating the cut side of sugarcane billets, preferably 2-50 mm, with UVB or UVC light or combinations thereof initiates stilbene production, particularly resveratrol and piceatannol. In an embodiment the cut sides of sugarcane billets of a predetermined thickness are irradiated with Ultraviolet-C or Ultraviolet-B light or combinations thereof at an intensity and for a duration of time sufficient to produce a significant increase in a level of one or more stilbenes in the irradiated billets compared to a level of stilbenes in billets that are not irradiated and the irradiated sugarcane billets are maintained for at least about three days up to about 20 days, to optimize stilbene levels.
