Molecular weight distribution of fructans extracted from <em>Agave salmiana</em> leaves

Background: In mezcal industry, Agave salmiana leaves are a crop residue and a potential source of fructans. Agave fructans are a soluble fiber that can act as prebiotic in gut microbiota. Questions and Hypotheses: The molecular weight distribution of agave fructans extracted from leaves of Agave salmiana depends on the region where agaves growth and on the subspecies. Studied species: Agave salmiana Otto ex Salm Dyck, spp. salmiana and Agave salmiana spp. crassispina. Study site: Twelve municipalities from Guanajuato México were sampled: Ocampo, San Felipe, San Diego de la Unión, Victoria, Xichú, Atarjea, Dolores Hidalgo, Doctor Mora, Santa Catarina, Tierra Blanca, San Miguel Allende and Comonfort. Methods: The base of the leaf close to the stem of Agave salmiana ssp. salmiana and A. salmiana ssp. crassispina plants, six years old, were harvested. Water soluble carbohydrates were extracted, the content molecular weight distribution of fructans was determined by HPLC-SEC. Results: An average of 0.7 % of soluble carbohydrates was recovered from the leaves. The molecular weight distribution of Agave salmiana fructans was: number average molecular weight: 3,209 g/mol; average molecular weight: 5,046 g/mol; number average degree of polymerization: 19; weight average degree of polymerization: 30. High polymerization degree fructans content was greater in Agave salmiana spp. salmiana (55 %) than in Agave salmiana spp. crassispina (47 %). Conclusions: The leaves of Agave salmiana contain a low proportion of high-molecular-weight fructans, compared to commercial agave fructans. The results demonstrated the technical feasibility to obtain fructans from Agave salmianaleaves.