ABSTRACT
RESUMEN Dentro de los tubérculos andinos de mayor importancia, después de la papa, se encuentra la ibia (Oxalis tuberosa Mol.) ya que constituye un alimento básico para las comunidades campesinas. Boyacá es uno de los departamentos de Colombia, en donde todavía existe la tradición de cultivar y consumir tubérculos como los cubios, ullucus y rubas o ibias, sin embargo están amenazados por la erosión genética. No existen estudios sobre estos recursos fitogenéticos en Boyacá, por lo cual el objetivo de esta investigación fue colectar y caracterizar morfológica y molecularmente materiales de ibias en este departamento. El análisis morfológico mostró que las características más discriminantes fueron: color de los tallos aéreos, pigmentación de las axilas, color del follaje, color de la flor, color del pedúnculo y pedicelo, color predominante de la superficie del tubérculo, color secundario de la superficie del tubérculo, color predominante y secundario de la pulpa, distribución del color secundario de la pulpa y forma de los tubérculos. El análisis de similitud diferenció a los materiales en dos grandes grupos, de acuerdo principalmente a características morfológicas como el color y hábito de floración. El valor de heterocigosidad promedio para la población total fue de 0.39 el cual se considera alto al compararse con otros estudios de diversidad genética en ibias. El análisis de varianza molecular y el Fst (coeficiente de diferenciación genética) muestran que existe una alta variabilidad genética entre los materiales de ibias evaluados la cual debe ser conservada y aprovechada dentro de futuros programas de mejoramiento.
ABSTRACT Among the most important Andean tubers, after potato, is the ibia (Oxalis tuberosa Mol.) because it is a staple food for peasant communities. Boyacá in one of the departments of Colombia, where there is still tradition to grow and consume tubers like cubios, ullucus and rubas or ibias; however, they are threatened by genetic erosion. There are no studies on these plant genetic resources in Boyacá, therefore the goal of this research was to collect and morphological and molecularly characterize ibias in this department. Morphological analysis showed that the most discriminate characteristic were color aerial stems, pigmentation armpits, foliage color, flower color, color peduncle and pedicel, predominant color of the tuber surface, secondary color of the surface tuber, dominant and secondary color of the pulp, distribution of secondary pulp color and shape of tubers. The similarity analysis discriminate the materials in two groups according mainly to morphological characteristics such as color and flowering habit. The value of average heterozygosity for the total population was 0.39, which is considered high when compared with other studies of genetic diversity in ibias. The analysis of molecular variance and Fst (coefficient of genetic differentiation) show that existed a high genetic variability among the ibias evaluated which it should be maintained and exploited in future breeding programs of Andean tubers.
ABSTRACT
The physical, chemical, and functional properties of starches isolated from the Andean tubers oca (Oxalis tuberosa M.), olluco (Ullucus tuberosus C.) and mashua (Tropaeolum tuberosum R. & P.) were studied. The tubers were obtained from a local grocery. The morphology of the starch granules (size and shape) was studied with scanning electron microscopy (SEM), which revealed ellipsoid, oval, conical, pear-shaped and prismatic forms: ellipsoids and oval granules with lengths up to 54.30 µm in oca; with lengths up to 32.09 µm for olluco starch granules; and with predominantly truncated spherical or oval forms and smaller dimensions (up to 16.29 um) for mashua starch granules. Amylose contents were similar among the samples: 27.60% (oca), 26.49% (olluco) and 27.44% (mashua). Olluco starch had less swelling power, forming opaque, less firm gels. All three starch gels showed the same stability on refrigeration and presented high syneresis under freezing temperatures, with a variation of 40.28 to 74.42% for olluco starch. The starches cooked easily, with high peak viscosity. The low gelatinization temperatures and high stability during cooling make these starches suitable feedstock for use in formulations that require milder processing temperatures and dispense freezing storage.
As propriedades físicas, químicas e funcionais de amidos isolados das tuberosas andinas, oca (Oxalis tuberosa M.), olluco (Ullucus tuberosus C.) e mashua (Tropaeolum tuberosum R. & P.), obtidas no comércio local, foram estudadas. A morfologia dos grânulos de amido foi avaliada por microscopia eletrônica de varredura (SEM) revelando formas elipsoidais, ovais, cônicas, periformes e prismáticas: grânulos elipsoides e ovais com dimensões de até 54,30 µm de comprimento para a oca, de até 32,09 µm para o amido de olluco, e com formas predominantemente esféricas ou ovais truncadas, de menores dimensões de até 16,29 µm para grânulos de amido de mashua. Os conteúdos de amilose foram similares entre as amostras: 27,60% (oca), 26,49% (olluco) e 27,44% (mashua). O amido de olluco teve menor poder de intumescimento, formando géis opacos e menos resistentes. Os géis dos três amidos mostraram a mesma estabilidade sob refrigeração e apresentaram alta sinérese após congelamento, com variação de 40,28 a 74,42% para amido de olluco. Os amidos tiveram cocção rápida com alto pico de viscosidade. A baixa temperatura de gelatinização e alta estabilidade durante a refrigeração fazem destes amidos matérias-primas adequadas para formulações que requeiram temperaturas brandas de processamento e que dispensem conservação por congelamento.