The physical, chemical and functional characterization of starches from Andean tubers: oca (Oxalis tuberosa Molina), olluco (Ullucus tuberosus Caldas) and mashua (Tropaeolum tuberosum Ruiz & Pavón)

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.

Quality parameters of some Brazilian panettones

In panettone, physical and chemical properties can determine the quality attributes in addition to consumer acceptability. The aim of this work was to assess the quality attributes of nine commercial samples of Brazilian panettone. Samples were characterized according to their physicochemical (moisture and color) aspects, quality attributes (specific volume, density and texture) and image analysis. The results of the statistical analysis (ANOVA and Tukey) showed significant differences (p<0.05) among the samples. Differences were observed in the specific volume and density. Samples showed moisture values between 22.83% and 26.86%. The texture analysis showed greater variation in values of crumb firmness (from 2.14 N to 7.55 N). Significant differences in crust (L* values between 31.58 and 44.85, a* between 12.34 and 16.47 and b* between 27.15 and 37.28) and crumb (L* values between 64.48 and 72.34, a* between -0.82 and 3.79 and b* between 33.43 and 40.97) color parameters were found for all samples. Through the image analysis, variability in the crumb structure was observed; however, the statistical analysis showed no significant differences between samples.

No panetone, propriedades físicas e químicas podem determinar além dos atributos de qualidade, a aceitabilidade pelos consumidores. O objetivo do presente trabalho é avaliar atributos de qualidade em nove amostras comerciais de panetone brasileiro. As amostras foram caracterizadas quanto a aspectos físico-químicos (umidade e cor), atributos de qualidade (volume específico, densidade e textura) e análise de imagem. Os resultados das análises estatísticas (ANOVA e Tukey) mostraram diferenças significativas (p < 0,05) entre as amostras. Diferenças no volume específico e densidade foram observadas. As amostras apresentaram valores de umidade entre 22,83% e 26,86%. A análise de textura do miolo mostrou elevada variação nos valores de firmeza (entre 2,14 N e 7,55 N). Diferenças significativas nos parâmetros de cor, para crosta (valores de L* entre 31,58 e 44,85, a* entre 12,34 e 16,47 e b* entre 27,15 e 37,28) e miolo (valores de L* entre 64,48 e 72,34, a* entre -0,82 e 3,79 e b* entre 33,43 e 40,97), foram encontrados em todas as amostras. Por meio da análise de imagem observou-se variabilidade na estrutura do miolo, porém a análise estatística não mostrou diferenças significativas entre as amostras.

Effects on starch and amylolytic enzymes during Lepidium meyenii Walpers root storage.

The high water content in maca (Lepidium meyenii W.) roots combined with the damage produced during or after harvest makes them vulnerable to attack by enzymes and microorganisms. Although starch degradation has been extensively studied, in maca roots there is a paucity of research regarding the starch reserves. In this paper, parameters of starch degradation are shown to be related to the action of amylolytic enzymes during storage at room temperature. Over the course of three weeks, the starch and protein content, soluble sugar, total amylolytic activity, and α- and ß-amylase activity were measured. In addition, the integrity of starch granules was observed by scanning electron microscopy. Despite the evidence of dehydration, there were no significant differences (p ≤ 0.5) in the total starch content or in the activities of α- and ß-amylase. After the third week the roots remained suitable for consumption. The results indicate a postharvest latency that can lead to sprout or to senescence, depending on the environmental conditions.