| Author | Thapa, Sabitri Siris |
| Call Number | AIT Thesis no.FB-19-01 |
| Note | A thesis submitted in partial fulfillment of the requirements for the
degree of Master of Science in
Food Engineering and Bioprocess Technology, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ;no.FB-19-01 |
| Abstract | Xylitol is a five-carbon sugar alcohol that is used as an antidiabetic sweetener due to its high sweetening power equivalent to that of sucrose but exerting 40% lower calories. It can be produced form agro-industrial wastes (sugarcane bagasse) through biotechnological approaches (microbial fermentation and enzymatic conversion). The aim of this study was to extract xylose from bagasse which can be converted into xylitol by fermentation. Ultrasound assisted alkaline pretreatment was optimized for xylan extraction. Effect of three different parameters; NaOH concentration (0.0-1.0 M), bagasse: alkali solution ratio (1:10-1:40) and ultrasonication time (10-40 min) on % true recovery of xylan was studied by response surface methodology (RSM). The optimized condition predicted by RSM was by using NaOH concentration (0.73 M), solid: liquid ratio (1:38.55) and ultrasonication time (34.77 min) resulting the maximum % xylan recovery value of 12.059% (w/w). Xylan extracted from the optimized condition was hydrolyzed by β-1,4-xylanase to produce D-xylose. Optimization of enzymatic hydrolysis revealed that the highest xylose production (84.32 ± 3.93 mg/g bagasse) was achieved with enzyme concentration of 800 U/g xylan at 48 h of incubation. During the investigation for the effect of different starter culture on xylitol production, sugarcane bagasse hydrolysates was fermented in the presence of yeast (Candida guilliermondii), bacteria (Corynebacterium glutamicum) and their mixed culture for different time periods (0-96 h). This study revealed that use of yeast for the fermentation of bagasse hydrolysates resulted in the highest xylose consumption (80.85 ± 2.51 %, w/v), xylitol production (2.39 ± 0.13 g/L) and xylitol yield (Yp/s= 0.43 ± 0.02 g/g) at 72 h as compared to other two cultures. Hence, C. guilliermondii was determined as the best starter culture for xylitol production from bagasse hydrolysates. Furthermore, xylitol present in the fermentation broth was partially purified and freeze dried to evaluate its structural characteristics by Fourier Transform Infrared (FTIR) Spectroscopy. Pure xylitol and freeze-dried xylitol spectra showed similar bands of transmittance at different wavenumbers and some peaks resembled to that of pure xylose indicating the presence of residual sugars (xylose). |
| Year | 2019 |
| Corresponding Series Added Entry | Asian Institute of Technology.|tThesis ;|vno. no.FB-19-01 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Anal, Anil Kumar; |
| Examination Committee(s) | Loc Thai Nguyen;Thammarat Koottatep; |
| Scholarship Donor(s) | Her Majesty the Queen’s Scholarships (Thailand); |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2019 |