Structural characteristics and in vitro digestibility of Mango kernel starches (Mangifera indica L.)

Structural characteristics and digestibility of starches isolated from the kernels of two mango cultivars (Chausa and Kuppi) were studied and compared with those of a commercial normal corn starch. Mango kernel starches showed an A-type X-ray diffraction pattern, with relative crystallinities of 35.4% and 38.3%, respectively for Kuppi and Chausa cultivars. The structural characterisation obtained, using high performance size exclusion column chromatography connected to multi-angle laser light scattering and refractive index detectors (HPSEC-MALLS-RI), revealed that the mango kernel starches had lower molecular weight (M_w) and radius of gyration (R_g) of amylopectin and amylose compared to those of corn starch. The M_w of amylopectin for Chausa and Kuppi starches were 179 × 10⁶ and 140 × 10⁶ g/mol, respectively. The amounts of readily digestible starch (RDS) and slowly digestible starch (SDS) were lower for mango kernel starch than those of corn starch. Resistant starch (RS) contents in the mango kernel starches (75.6% and 80.0%, respectively) were substantially higher than those of corn starch (27.3%). The glycemic index (GI) values for mango kernel starches were 48.8 and 50.9 (for Chausa and Kuppi, respectively), whereas that of corn starch was 74.8, indicating that the mango kernel starch granules were highly resistant to digestion with significant contents of RS.