Anatomical and physical changes in leaves during the production of tamales.
OBJECTIVE
Tamale preparation has a long tradition in Mexico. To understand which material properties have been considered important for this purpose throughout the years, a study was conducted of the anatomical, chemical, and mechanical properties of the leaves of four plant species used in tamale preparation in Veracruz, Mexico: Calathea misantlensis, Canna indica, Musa paradisiaca, and Oreopanax capitatus.


METHODS
Four cooking treatments were considered: fresh (F), roasted (soasado, R), steamed (S), and roasted plus steamed (R/S). Chemical, anatomical, and mechanical analyses were conducted before and after each treatment. Leaf samples were tested for tensile strength at both parallel and perpendicular orientation relative to the fibers.


RESULTS
Musa paradisiaca had the highest proportion of cellulose, while the remaining species shared similar lower proportions. Leaves were stronger and stiffer in the longitudinal direction of the fibers. Musa paradisiaca leaves had higher values of mechanical strength than the other species. The cooking process that most affected the mechanical properties was steaming.


CONCLUSIONS
The chemical constituents of the leaves are closely correlated with their physical properties. The treatment that caused the greatest decrease in leaf physical integrity was steaming, while the combination of roasting and steaming showed similar results to those of steaming alone. No evident anatomical changes are produced by any of the treatments. This is one of the few studies comparing physical, chemical, and anatomical characteristics of leaves used for human consumption, before and after cooking.
Instituto de Ecología, A.C. Carretera Antigua a Coatepec No. 351. El Haya. Xalapa, Veracruz, C.P. 91070 Mexico. guillermo.angeles@inecol.edu.mx
Guillermo
G
Angeles
Maite
M
Lascurain
Raymundo
R
Davalos-Sotelo
Reyna Paula
RP
Zarate-Morales
Fernando
F
Ortega-Escalona
D027481:Araliaceae / Q000033:anatomy & histology* / Q000737:chemistry / Q000166:cytology; D027581:Cannabaceae / Q000033:anatomy & histology* / Q000737:chemistry / Q000166:cytology; D002482:Cellulose / Q000737:chemistry; D003296:Cooking; D055119:Elastic Modulus; D008031:Lignin / Q000737:chemistry; D032426:Marantaceae / Q000033:anatomy & histology* / Q000737:chemistry / Q000166:cytology; D028521:Musa / Q000033:anatomy & histology* / Q000737:chemistry / Q000166:cytology; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000737:chemistry / Q000166:cytology; D011134:Polysaccharides / Q000737:chemistry; D013718:Tensile Strength
D011134:Polysaccharides; C007916:hemicellulose; D002482:Cellulose; D008031:Lignin
chemical constituents; heat transformation; leaf structure; tensile strength