Amylose content and micromorphology of popcorn progenies with different popping expansion volumes

Abstract

Popcorn (Zea mays var. everta) has a higher commercial value than common maize, in addition to being a popular food among consumers. Today, there is a constant search for cultivars with superior performance for several traits of interest in the case of popcorn, yield and popping expansion. On this basis, this project proposes to characterize progenies of popcorn with different values of expansion capacity regarding chemical composition and micromorphology. Kernels from the fifth cycle (C5) of intrapopulation recurrent selection were evaluated. The progenies were selected based on the popping expansion volume of their kernels. The kernels were quantified for amylose and analyzed for starch granule arrangement and pericarp thickness by scanning electron microscopy. Progenies with low popping expansion volume (0 and 7 mL g-1) showed amylose contents of 21.24 and 20.18%, respectively; a less compact endosperm, with individual starch granules interspaced with empty spaces; and pericarp thickness between 40.94 and 38.99 µm, respectively. By contrast, progenies with high popping expansion volume (30 and 35 mL g-1) showed amylose contents of 23.92 and 26.10%; a vitreous endosperm; more-compact starch granules without empty spaces in between; and pericarp thickness between 107.66 and 107.84 µm. Progenies with higher popping expansion volume exhibited a thicker pericarp, a high amylose percentage and a more-compact endosperm, whereas those with the lower expansion volumes showed a thinner pericarp, a lower amylose percentage and individual starch granules.

Influence of agronomic and kernel‐related properties on popping expansion in popcorn

“…These results corroborate those of Freire et al. (2020), who demonstrated that the progenies with highest PE volume had coarser pericarps. Thus, the importance of kernel pericarp thickness in the complex process of popcorn kernel popping is highlighted, suggesting that this trait can favor gains in PE both in the process of direct and indirect selection.…”

“…On the other hand, Freire et al. (2020) reported that PE is strongly associated ( r = .95; p ≤ .01) with a higher starch percentage. It should be noted that the study by Freire et al.…”

“…It should be noted that the study by Freire et al. (2020) estimated the amylose content, in which popcorn with low expansion capacity (0 and 7 ml g −1 ) had lower amylose content (21.24 and 20.18%, respectively) and popcorn with high expansion capacity (30 and 35 ml g −1 ) had a higher amylose content (23.92 and 26.10%, respectively).…”

“…(2006) and Freire et al. (2020). With regard to these aspects, it is worth emphasizing that the physical traits are generally related to the chemical composition (Park et al., 2000).…”

“…Thus, studies focused on physical traits have investigated kernel size and density (Cabral et al., 2016; Carpentieri‐Pípolo et al., 2002; Park & Maga, 2002; Rangel et al., 2011; Song et al., 1991), percentage of unpopped kernels (Tian et al., 2001), flake size (Tian et al., 2001), and influence of pericarp thickness (Freire et al., 2020; Mohamed et al., 1993; Silva et al., 1993). In addition, studies related to the kernel chemical composition have determined the protein, starch, and oil contents, as, for example, those of Borras et al.…”