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Shah Zaib Fareed. Production of Xylooligosaccharides from barley malt residue by microwave-assisted enzymatic hydrolysis and evaluation of their prebiotic potential. Master's Degree(Food Science and Technology). Chiang Mai University. Library. : Chiang Mai University, 2025.
Production of Xylooligosaccharides from barley malt residue by microwave-assisted enzymatic hydrolysis and evaluation of their prebiotic potential
Abstract:
Barley malt residue (BMR), an abundant by-product of the malting and brewing industries, was investigated for its potential as a sustainable raw material to produce xylooligosaccharides (XOS), recognized for their prebiotic benefits. The study employed microwave-assisted enzymatic hydrolysis to enhance the efficiency of XOS production, focusing on optimizing key process variables: microwave power (10001400 W), exposure time (26 min), and xylanase dosage (2100 U/g substrate). Response surface methodology using a Box-Behnken design (BBD) was applied to model the relationships between these variables and the yields of XOS. The predictive models demonstrated a strong correlation with experimental data, confirming their validity. Under optimal conditions, microwave power of 1235.1 W, exposure time of 6 min, and xylanase concentration of 89.12 U/g substrate a maximum XOS yield of 208.05 mg/g substrate was obtained after 4 h of enzymatic hydrolysis. Different purification strategies were compared to improve the purity of the XOS product. Treatment with Saccharomyces cerevisiae proved superior to conventional methods such as activated carbon adsorption and ethanol precipitation, leading to its selection for further studies. The purified BMR XOS was characterized using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) to determine its oligosaccharide composition. Fourier transform infrared spectroscopy (FTIR) confirmed the molecular structure and sugar components of the extracted XOS. In vitro fermentation assays were performed to evaluate the prebiotic activity of BMR-XOS with selected probiotic strains, includingLactococcus lactis TISTR 1401, Levicaseibacillus brevis FS 2.1, and Lactobacillus casei TISTR 1463. The results revealed prebiotic effects comparable to those of commercial XOS, galactooligosaccharides (GOS), and inulin. BMR-XOS significantly enhanced the growth rate of L. lactis TISTR 1401, L. brevis FS 2.1, and L. casei TISTR 1463, achieving maximum specific growth rates (μmax) of 1.085, 0.891, and 0.532 h−1, respectively. These findings highlight the functional equivalence of BMR-derived XOS to established prebiotic products. This research successfully demonstrates that barley malt residue can serve as an efficient and sustainable source for XOS production. The process not only adds value to an agro-industrial residue but also supports the development of eco-friendly, health-promoting ingredients for the food and nutraceutical industries.