Abstract
Proteinase inhibitor 2 (PI2), isolated from potatoes is associated with the release of cholecystokinin (CCK), a satiety factor in humans. PI2 is the active ingredient of Slendesta® Potato Extract. The effect of harvest date on the levels of proteinase inhibitor 2 (PI2), total protein content and total glycoalkaloids (TGA) was studied in two potato (Solanum tuberosum L.) clonal lines. In addition, tuber specific gravity, tuber yield, and tuber size distribution were measured in response to harvest date. The two potato clonal lines designated as KI-PSt0018 and KI-PSt0034 were planted in a randomized complete block design with four replicates. Tubers were harvested at four different dates during the growing season; 4 weeks and 2 weeks to vine-kill; at vine-kill; and 2 weeks post vine-kill. Sample tubers from these four harvest dates and from 2 months of storage, post vine-kill stage were analyzed for PI2, total protein and TGA. Harvesting at different dates had a significant influence on most of the traits studied in both clonal lines. The two clonal lines responded differently to different harvest dates for all traits except PI2 and specific gravity. PI2 levels increased with maturity with the highest levels observed at full maturity in both clonal lines. The protein levels did not show any specific trend in either clonal line. TGA levels increased gradually in small increments with maturity in KI-PSt0018 but did not have a clear pattern in KI-PSt0034. Tuber yield and size increased with maturity of the crop in both clonal lines. Higher tuber yields were seen during final vine-kill and 2 weeks post vine-kill compared to the earlier stages of harvest in both clonal lines. Tuber specific gravity declined when tubers were left in the ground for 14 to 21 days after vine-kill in both clonal lines. This study indicated harvest of potato prior to vine-kill is not beneficial for the extraction of PI2 for use as functional food or dietary supplement ingredient.
Resumen
El inhibidor de proteinasa 2 (PI2) aislado de papas se asocia cercanamente con la liberación de colecistocinina (CCK), un factor de saciedad en humanos. PI2 es el ingrediente activo del extracto de papa Slendesta®. Se estudió el efecto de fecha de cosecha en los niveles del inhibidor de proteinasa PI2, así como también el contenido total de proteína y glicoalcaloides totales (TGA) en dos líneas clonales de papa (Solanum tuberosum L.). Además, se midieron la gravedad específica de tubérculo, su rendimiento y la distribución de su tamaño en respuesta a la fecha de cosecha. Se plantaron las dos líneas clonales, designadas como KI-PSt0018 y KI-PSt0034, en un diseño de bloques completos al azar con cuatro repeticiones. Se cosecharon los tubérculos en cuatro diferentes fechas durante el ciclo de cultivo; cuatro y dos semanas antes de la eliminación del follaje; durante la eliminación del follaje; y dos semanas después. Se analizaron para PI2, proteína total y TGA, muestras de tubérculos de estas cuatro fechas de cosecha y de dos meses de almacenamiento después de quema de follaje. Las cosechas en diferentes fechas tuvieron una influencia significativa en la mayoría de las variables estudiadas en ambas líneas clonales. Estas respondieron de manera diferente a las fechas de cosecha para todos los caracteres excepto para PI2 y gravedad específica. Los niveles de PI2 se incrementaron con la madurez, con los niveles más altos observados en completa madurez en ambos clones. Los niveles de proteína no mostraron alguna tendencia específica en cualquiera de los clones. Los niveles de TGA aumentaron gradualmente en pequeños incrementos con la maduración en KI-PSt0018 pero no tuvieron un patrón claro en KI-PSt0034. El rendimiento y tamaño de tubérculo aumentaron con la maduración del cultivo en ambos clones. Los mayores rendimientos de tubérculo se observaron durante el final de la destrucción del follaje y dos semanas después, comparados con los estados más tempranos de cosecha en ambos clones. La gravedad específica de tubérculo declinó cuando se dejaron en el campo de 14 a 21 días después de la destrucción del follaje en los dos clones. Este estudio indicó que la cosecha de la papa antes de eliminar follaje no es benéfica para la extracción de PI2 para usarse como alimento funcional o como ingrediente en suplementos de dietas.
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Narasimhamoorthy, B., Zhao, L.Q., Liu, X. et al. Effect of Harvest Date on PI2, Total Protein, TGA Content and Tuber Performance in Potato. Am. J. Potato Res. 90, 561–569 (2013). https://doi.org/10.1007/s12230-013-9329-9
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DOI: https://doi.org/10.1007/s12230-013-9329-9