ABSTRACT
Salted noodles were prepared with different contents of wheat grits and plantain starch (PS). The blends were hydrated with 2% NaCl (w/v), homogenized, and the resulting doughs were sheeted through a pasta machine, cut into strips ~30cm in length, cooked, and their composition and in vitro starch digestibility was assessed. Moisture (6.43-7.60%) and ash contents (2.08-3.12%) increased by the addition of PS. Fat level decreased from 0.41 to 0.31% as the substitution of wheat grits increased. Results showed a 7.39% lower total starch content in the control sample as compared to the noodle containing 30% PS. A similar pattern was observed for potentially available starch content, but the difference was greater (12.46%). Approximately 50% of total resistant starch (RS) in the noodles was resistant starch associated to fiber, showing that a part of RS is due to the physically inaccessible and retrograded starch fractions. Pure wheat (control) noodles presented a greater final a-amylolysis value, which is suggestive of potentially lower glycemic impact for the plantain/wheat products.
Se elaboraron tallarines salados con diferentes contenidos de sémola de trigo y almidón de plátano (AP). Las mezclas fueron hidratadas con solución NaCl 2% (p/v), homogenizadas y las masas laminadas en una máquina para elaborar pasta. Se cortaron en tiras de ~30cm de longitud, se cocinaron y se estudió su composición, así como la digestibilidad del almidón in vitro. El contenido de humedad (6,43-7,60%) y cenizas (2,08-3,12%) incrementaron con la adición del AP. El contenido de lípidos disminuyó de 0,41 a 0,31% conforme el nivel de sustitución de la semolina incrementó. El contenido de almidón total fue 7,39% menor en la muestra control comparado con el tallarín con 30% de AP. Un comportamiento similar se encontró en el almidón disponible, pero la diferencia fue mayor (12,46%). Aproximadamente 50% del almidón resistente total (AR) en los tallarines fue almidón resistente asociado a fibra, mostrando que una parte del AR es debido al almidón físicamente inaccesible y al almidón retrogradado. El valor final de la a-amilólisis fue mayor en el control de trigo puro, lo cual sugiere que los tallarines elaborados con la mezcla semolina/AP tienen menor impacto glucémico.
ABSTRACT
Se estudió la composición química y digestibilidad in vitro del frijol "ayocote" cocido (Phaseolus coccineous). El contenido de proteína y cenizas fue de 20,46 y 1,39%, respectivamente, los cuales se encuentran entre los más bajos reportados para el género Phaseolus. En el caso de los lípidos su contenido fue relativamente alto (3,31%). Los valores de almidón disponible (AD) disminuyeron con el tiempo de almacenamiento, variando desde 37,93% (muestra recién cocinada) hasta 32,18% (muestra almacenada por 96h). El comportamiento inverso se encontró para el contenido de almidón resistente (AR). Los valores estuvieron entre 2,24% (muestra control) y 3,49% (muestra almacenada por 96h), lo cual representa un incremento del 56% en el contenido de AR. El almidón resistente asociado a la fibra dietética (ARAF) presentó un comportamiento similar, ya que los valores se incrementaron con el tiempo de almacenamiento. La velocidad de a-amilólisis disminuyó con el tiempo de almacenamiento; por ejemplo, las muestras almacenadas por 96h mostraron una velocidad de digestión lenta. El índice glucémico estimado estuvo entre 62,9 y 59,7%, sugiriendo que el almidón del frijol "ayocote" libera muy lentamente la glucosa cuando es hidrolizado por las enzimas digestivas.
"Ayocote" beans (Phaseolus coccineous) were cooked and studied regarding their chemical composition and in vitro starch digestibility. Protein and ash contents were 20.46 and 1.39%, respectively, which are among the lowest levels for seeds of the Phaseolus genus. On the contrary, lipid content was relatively high (3.31%). Available starch (AS) values decreased with storage at 4ºC, changing from 37.93 (freshly cooked "control" seeds) to 32.18% (seeds stored for 96h). An inverse pattern was found for resistant starch (RS) content. RS ranged between 2.24 and 3.49% for the control and 96h-stored samples, which represents a 56% increase in the RS content. Resistant starch associated to dietary fiber (RSAF) had a similar behavior, as its values increased with the storage time. The a-amylolysis rate decreased with storage, i.e. long-stored (96h) cooked samples exhibited slower starch digestion features. The predicted glycemic index ranged between 62.9 and 59.7%, suggesting slow glucose-release features for starch in "ayocote" beans.
Estudou-se a composição química e digestibilidade in vitro do feijão "ayocote" cozido (Phaseolus coccineous). O conteúdo de proteína e cinzas foi de 20,46 e 1,39%, respectivamente, os quais se encontram entre os mais baixos reportados para o gênero Phaseolus. No caso dos lípidos seu conteúdo foi relativamente alto (3,31%). Os valores de amido disponível (AD) diminuíram com o tempo de armazenamento, variando desde 37,93% (amostra recém cozida) até 32,18% (amostra armazenada por 96h). O comportamento inverso encontrou-se para o conteúdo de amido resistente (AR). Os valores estiveram entre 2,24% (amostra controle) e 3,49% (amostra armazenada por 96h), o qual representa um incremento de 56% no conteúdo de AR. O amido resistente associado à fibra dietética (ARAF) apresentou um comportamento similar, já que os valores se incrementaram com o tempo de armazenamento. A velocidade de a-amilólisis diminuiu com o tempo de armazenamento; por exemplo, as amostras armazenadas por 96h mostraram uma velocidade de digestão lenta. O índice glicêmico estimado esteve entre 62,9 e 59,7%, sugerindo que o amido do feijão "ayocote" libera muito lentamente a glicose quando é hidrolisada pelas enzimas digestivas.
ABSTRACT
Potato, corn and banana starches were blended in various combinations and ratios. Stability and clarity, freeze-thaw stability, water retention capacity and apparent viscosity of the pastes (prepared with a hydrothermic treatment using 100 C for 30 min) were evaluated. In general, the samples stored at room temperature (28 C) presented stability as well as low retrogradation rate. However, in the samples stored at 4 ÆC the propagation and maturation of crystals in the amylopectin component were favored, increasing sample retrogradation. A synergistic effect was shown in some starch blends. The blends had poor stability to freeze-thaw cycle, but a high synergestic effect was presented in water retention capacity. Potato: banana and corn: potato blends showed a synergistic effect in the apparent viscosity and in general, starch blends had stability during the 30-min test.