Utilization of by-products from the tequila industry. Part 2: potential value of Agave tequilana Weber azul leaves

The leaves of the agave plant are left in the field after harvesting the heads for tequila production. Different types of agave leaves were isolated, classified, and their content in the total plant determined. The usable fractions were collected and their properties determined. Of the total wet weight of the agave plant, 54% corresponds to the agave head, 32% corresponds to materials which could be usable for sugar and fiber production which leaves 14% of the wet plant without apparent utility. The fractions with higher total reducing sugars (TRS) content were the fresh fraction of partially dry leaves stuck to the head and the leaf bases with a TRS content of 16.1% and 13.1%, respectively. The highest TRS concentration (16–28%) is in the agave head which is used for tequila production. The leaves are 90–120 cm long and 8–12 cm wide and contain fiber bundles that are 23–52 cm long and 0.6–13 mm wide. The ultimate fiber length is approximately 1.6 mm with an average width of 25 μm. There are several types of leaf fibers that can be utilized depending on what part of the plant they come from and what product is desired. Agave leaf fibers were pulped using a soda pulping process and the pulp was hand formed into test sheets. Test sheets made from pulped agave leaf fibers had a breaking length comparable to paper made from both pine and eucalyptus fibers, but the tear index and burst index were lower than the other two papers.