2.1. Raw materials
AV leaves were collected from a dry area of northern Mexico(Durango, Dgo.), from a cultivated area of 2500 m2, with a production of 2.5 tons per year under controlled irrigation and constant organic fertilizer every two months. These plants have a thick and short herbaceous stem with a diameter of 10 cm and height of 20e25 cm on average, prior to the stage of flourishing. The leaves have S shape towards the tip (center are erect or slightly curved and thinner) with 70e90 cm on average height and 8 cmthick. Only the
bright green leaves without brown spots with 24e30 months-old
on average that grew in the outer part of the plant were cut.