Physicochemical, structural, and digestibility properties of enzymatic modified plantain and mango starches

The effect of two enzymatic treatments (increasing the branch density of starch and shortening of AP and amylose chains) on the fraction of slowly digestible starch (SDS) and resistant starch (RS) of plantain (Musa paradisiaca L.) and mango (Mangifera indica L.) starches was investigated. The enzymatic modifications were carried out using beta-amylase (beta-AMY) and beta-amylase-transglucosidase (beta-AMY-TGs), in gelatinized starches. Plantain starch showed an increase from 10.9 to 18.5% of SDS, when it was modified by beta-AMY-TGs, while the treatment with beta-AMY alone showed reduction from 10.9 to 7.1% in SDS. RS content increased with both treatments. On the other hand, mango starch showed an increase in SDS from 6.3 to 22.3% using beta-AMY treatment and from 6.3 to 11.7% using beta-AMY-TGs treatment. The latter treatment also increased RS content. The enzyme modified starches showed a reduction in the values of molar mass and gyration radius compared with the native starch. The content of short chains of AP, particularly in the DP range 512, increased, the percentage of crystallinity decreased in treated starches, and 1H NMR spectra showed a significant increase of a-(1???6) linkages in the starches modified with beta-AMY-TGs. These characteristics were related to an increase in the slow and resistant digestion properties of plantain and mango starches.