Physicochemical, functional, pasting and thermal properties of resistant starchtype III from banana (Musa acuminata X balbisiana cv. Awak) pseudostem

In Malaysia, banana is the second most widely cultivated fruit. The banana pseudostem (BP) is cut and dumped as waste after harvesting. Unfortunately, pseudostem is currently underutilised as a functional food ingredient due to its high-quality starch content. Therefore, this study aimed to determine the proximate compositions, physical attributes, and functional characteristics of starches produced from BP, in comparison with commercial starches, such as potato starch (PS) and corn starch (CS). Native starch from banana pseudostem (BPNS) was isolated. Then, resistant starch type III (RS3) was prepared from native starch (RS3BP) by an autoclaving process. The starches were subjected to physicochemical (i.e., proximate composition, water activity, bulk density, and colour), functional (i.e., amylose, amylopectin, water holding, and oil holding capacities), pasting (by using rapid visco analyser), and thermal properties determination (by using differential scanning calorimetry). The results showed that there were significant (p<0.05) increases in the amylose content of RS3BP after the autoclaving process. The water and oil holding capacities of BPNS did not change after autoclaving. The results of pasting and thermal properties indicated that BPNS contained a stronger starch granule and greater thermal stability than commercial starches (PS and CS). In addition, the autoclaving process decreased significantly (p<0.05) the content of moisture, crude protein, crude fat, and ash but increased significantly (p<0.05) the total carbohydrate and energy values in BPNS. The autoclaving process also resulted in a significant (p<0.05) darker and red-yellowish colour of RS3BP than other starches. In conclusion, the findings of this study demonstrated that the isolated BPNS has good starch granule stability and retains its functional properties after autoclaving during the production of RS3BP, even with an increased energy source. Therefore, BP can be considered a viable alternative raw material for producing native starch or resistant starch type III.