Characterization of young bamboo culm starch from Dendrocalamus asper

Abstract

The search for new and natural ingredients has been stimulated by the food and non-food industries, and the fresh young bamboo culm of Dendrocalamus asper emerges as promising for industrial production due to its composition with >10% of starch. So, this study aimed to characterize starch, extracted in aqueous solution, from three different parts (bottom, middle and top) of the young bamboo culm of D. asper (SB, SM and ST, respectively). Morphological and physicochemical characteristics of the young bamboo culm starches were evaluated, besides thermal properties, and the obtained data were evaluated by ANOVA and Scott-Knot test (p < 0.05). The starches presented pale yellow coloration, with high luminosity (L* > 89), and lower index in the red region. SEM images showed compound granules, which under polarized light exhibit a Maltese cross. The starches presented polyhedral shape and small size with an average diameter of 5.4 μm. All the samples presented low moisture (7.0 g/100 g), protein (2.0 g/100 g), lipid (0.3 g/100 g) and ash (1.0 g/100 g) contents. ST and SB showed apparent amylose content similar to starches from cereals and isolated from bamboo seeds. This agress to molecular size distribution of starch chains, since the SB, SM and ST presented amylopectin levels higher than those of amylose, as well as normal starches. The chain length of amylopectin presented the main peak at DP 12–13 and the second on at DP 43, similar to cereals like wheat, rice and barley. Its chain has higher proportion of short chains, which corroborates with the A-type polymorph presented. Concerning about thermal properties, all the samples presented high gelatinization temperature (>78 °C) and low enthalpies values (<6.35 J·g−1), which indicates the greater molecular organization. The gelatinization temperatures of gelatinized starches were lower than the native ones. The physicochemical and thermal characteristics of the obtained starches corroborate with the success of the extraction, which keep the starch granule native, and were similar to those of other starches already used in food and non-food products.