| Summary: | 碩士 === 國立中興大學 === 食品暨應用生物科技學系所 === 106 === Banana is rich in a variety of functional materials, especially resistant starch in green bananas. Resistant starch can be degraded during cooking, and thus the industrial applicability is limited by the reduction in the resistant starch levels. The objective of this work was to develop the procedures of starch production and modification, and the basic physicochemical, structural and morphological characteristics of different starch samples were evaluated.
The study was carried out in two stages. In the first stage, banana starches were isolated from green bananas with four kinds of solutions, including RO water (control), X, Y, and Z. The processing method was developed using the most suitable solution. In the second stage, the starch from the first stage was treated with citric acid in two ways, dry-heat and heat-moisture treatments. Physicochemical properties of different modified starch samples were evaluated.
The result showed that adding X, Y and Z solutions could improve the efficiency of banana starch isolation. Compared with the control (RO water), an addition of Z solution resulted in a significant (p ＜ 0.05) increase in yield (54%), purity (21%) and resistant starch content in total starch (64.01%) of banana starch. An improvement in the sample color changes due to enzymatic browning (ΔE* = 23.24) was observed.
For the dry-heat treatment, while conducting the reaction at 140℃ for 5 h with a C of CAS (DHBSC-C/5 starch), high resistant starch content in total starch (98.57%) was obtained. Compared with the native banana starch (NBS), DHBSC-C/5 starch had a significant (p ＜ 0.05) increase in thermal stability and changes in crystalline, but reduction in solubility and swelling power. In addition, there was no gelatinization peak formed in RVA amylographic curve and DSC thermogram in DHBSC-C/5 group. On the other hand, the suitable condition for heat-moisture treated banana starch was heating at 90℃ for 16 h with a moisture content at 30% (CHMBS-90/16). CHMBS-90/16 group was found to have an increase in the relative crystallinity (2.7%) and had significantly (p ＜ 0.05) higher gelatinization temperature (81.48-92.11℃) and enthalpy (ΔH) of endothermic peak than those of the NBS group (66.26-78.89℃). After the boiling process (100C for 30 min), CHMBS-90/16 group had a higher level of resistant starch in the total starch (25.98%) than that in the NBS (5.99%). In conclusion, our results have revealed that these two treatments as mentioned above could improve the thermal stability of native banana resistant starch.
|
|---|
