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Friday, May 17 • 2:30pm - 3:00pm
(Research & Technical Studies) Effects of Relative Humidity and Temperature on Morphology and Chemical Composition of Debarked Maize Stems, a Material of Lightweight Sculptures

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In New Spain – Mexico today –, maize stem was used in a lightweight sculpting technique that was a synthesis of the Prehispanic and European traditions. These sculptures are mostly made from the stem of the maize plant, with or without bark. The use of stems may have two functions: structural, when the stem is used as the structural core, and volumetric, when it is used as a modeling paste (milled maize stem agglutinated with animal glue). Despite the importance of maize stem sculptures in Latin America and Spain, little is known about its degradation mechanisms and appropriate methods for their conservation. Therefore, this research determines the effects of different relative humidity and temperature treatments on morphology and chemical composition of the debarked maize stems. Also, dissociated and naturally aged samples from a New Spain sculpture were analyzed and compared with the treatments results. The maize stems treated samples were classified into lower and upper sections according to the distance from the root plant, while the New Spain samples were obtained from a New Spain temple in Michoacán, México. The samples underwent nine treatments: T1 (25%RH/25°C), T2 (25%RH/50°C), T3 (25%RH/75°C), T4 [control] (50%RH/25°C), T5 (50%RH/50°C), T6 (50 %RH/75°C), T7 (75%RH/25°C), T8 (75%RH/50°C) and T9 (75%RH/75°C). Morphology was determined using SEM and histochemical staining methods applying toluidine, safranine and phloroglucinol-HCl. For chemical characterization, cellulose and hemicellulose content was determined by sodium chlorite method, while lignin was quantified according to the Klason method. In addition, FTIR-ATR spectroscopy was used for identification of chemical groups. The chemical characterization shows that the upper section stems have a higher hemicellulose content than the lower section and that the higher temperatures decrease the percent of this component, such effect is aggravated by increasing the relative humidity, even beginning to affect cellulose. By morphological characterization, it was observed that the lower section stems tissues are weaker and as the hemicellulose decreases, the non-lignified cell walls become more susceptible to deformations and ruptures, mainly in parenchyma and phloem. For FTIR-ATR spectroscopy, it was identified that the higher parameters of relative humidity and temperature decrease the transmittance of the signal 1736 cm-1 that is related with stretching vibrations in the C=O alkyl-ester bonds that form the hemicellulose and pectin of the cell walls. In addition, the New Spain samples characterization determined a drastic low hemicellulose and cellulose percentage supporting the treatments results. The principal contributions of this study are the identification of the more vulnerable structural components in the maize stems, provide different methods to diagnose their degradation degree, and recognize the riskier relative humidity and temperature treatments, these allows to improve and develop accurate preventive and conservation methods. In further studies, mechanical resistance of the treated samples will be tested and compared with thus far obtained results.

Speakers
avatar for Alfredo Adolfo Ortega-Ordaz

Alfredo Adolfo Ortega-Ordaz

Conservator, Museo de El Carmen/ Laboratorio de Análisis y Diagnóstico del Patrimonio
Alfredo Adolfo Ortega-Ordaz, born in 1993 at Durango, Mexico, is part of the Conservation Department of the “Museo de El Carmen” in Mexico City, were he works with different types of New-Spain artworks and on a parallel project of mummies conservation. In 2011, he began his studies... Read More →

Co-Author
CC

Carlos Cruz-Cárdenas

Researcher, Centro Nacional de Recursos Geneticos/Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias
Carlos Iván Cruz Cárdenas was born on August 11, 1986 in Chiapas estate of México. In 2005 he began his studies at the Instituto de Biociencias (IBC) of the Universidad Autónoma de Chiapas (UNACH), in June 2010 with his research work Effect of biofertilizers and growth regulators... Read More →
avatar for Emanuel Bojóquez-Quintal

Emanuel Bojóquez-Quintal

Profesional de Investigación, Laboratorio de Análisis y Diagnóstico del Patrimonio-LADIPA
Emanuel Bojórquez-Quintal, born in 1983 at Yucatan, Mexico, is CONACYT-Professor assigned to the Laboratorio de Análisis y Diagnóstico del Patrimonio (LADiPA) of El Colegio de Michoacán A.C. (COLMICH). Member of the National System of Researchers (Mexico): Candidate Level 2017-2019... Read More →
ES

Esteban Sánchez-Rodríguez

Scanning Electron Microscope operator, El Colegio de Michoacán
Esteban Sánchez-Rodríguez, born in 1965, is technical staff assigned to the operation and maintenance of the Scanning Electron Microscope (SEM) in the “Laboratorio de Análisis y Diagnóstico del Patrimonio” (LADiPA) of “El Colegio de Michoacán” (COLMICH). In 1991 he obtained... Read More →
LR

Luis Rojas-Abarca

Mass Spectrometer operator, Laboratorio de Analisis y Diagnóstico del Patrimonio
Luis Rojas-Abarca born in 1980, is technical staff assigned to the operation of the mass spectrometer by Direct Analysis in Real Time (DART) carrying out the analysis of cultural and natural heritage samples at the “Laboratorio de Análisis y Diagnóstico del Patrimonio” (LADiPA... Read More →
avatar for Ángela Ku-González

Ángela Ku-González

Academic Research Technician, Centro de Investigación Científica de Yucatán
Angela Francisca Ku González, born in 1974 at Yucatán, Mexico, is an academic research technician in “Unidad de Bioquimica y Biología Molecular de Plantas” of “Centro de Investigación Científica de Yucatán A.C.” (CICY). Currently, responsible for the laboratory of microscopy... Read More →


Friday May 17, 2019 2:30pm - 3:00pm
Nehantic/Pequot/Paugussett Rooms Sky Convention Center, Mohegan Sun
  • Track Research & Technical Studies
  • Ticketed Included in Main Registration
  • Authors in Publication Order Alfredo Adolfo Ortega-Ordaz, Esteban Sánchez-Rodríguez, Luis, Rojas-Abarca, Ángela Ku-González, Carlos Cruz-Cárdenas, Emanuel Bojórquez-Quintal
  • Abstract ID 18616
  • Tags maize stems,lightweight sculptures,relative humidity,temperature chemical characterization,morphological characterization

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