Tender coconut husk waste as a potential source for extraction of Xylooligosaccharides

The present study demonstrates the application of alkali treatment coupled with steam for the extraction of xylan followed by its enzymatic hydrolysis for the production of xylooligosaccharide (XOS) from coconut husk. The chemical analysis of the husk revealed the presence of hemicelluloses, along with cellulose, lignin and ash demonstrating its suitability for XOS extraction. Application of 20% of NaOH coupled with steam treatment for 60 min enabled the fractionation of approximately 93% xylan from the husk. Response surface methodology was employed to optimize the different variables i.e. enzyme concentration, pH, temperature and time for the extraction of XOS from xylan, wherein, enzyme concentration and temperature were the influential variables affecting xylose yield and enzyme concentration, temperature, time and pH were influential variables affecting xylobiose yield significantly. FTIR analysis of the husk also confirmed the presence of hemicelluloses, whereas, the presence of xylan and XOSmix was also confirmed in the extracted mass. In nutshell, the present study was successful in establishing the suitability of coconut husk for extraction of xylan and XOS which can be further used as a prebiotic.

BackgroundPopulus (poplar) tree species including hybrid varieties are considered as promising biomass feedstock for biofuels and biochemicals production due to their fast growing, short vegetative cycle, and widely distribution. In this work, poplar was pretreated with acetic acid (AC) to produce xylooligosaccharides (XOS), and hydrogen peroxide–acetic acid (HPAC) was used to remove residual lignin in AC-pretreated poplar for enzymatic hydrolysis. The aim of this work is to produce XOS and monosaccharides from poplar by a two-step pretreatment method.ResultsThe optimal conditions for the AC pretreatment were 170 °C, 5% AC, and 30 min, giving a XOS yield of 55.8%. The optimal HPAC pretreatment conditions were 60 °C, 2 h, and 80% HPAC, resulting in 92.7% delignification and 87.8% cellulose retention in the AC-pretreated poplar. The two step-treated poplar presented 86.6% glucose yield and 89.0% xylose yield by enzymatic hydrolysis with a cellulases loading of 7.2 m/g dry mass. Very high glucose (93.8%) and xylose (94.6%) yields were obtained with 14.3 mg cellulases/g dry mass. Both Tween 80 and β-glucosidase enhanced glucose yield of HPAC-pretreated poplar by alleviating the accumulation of cellobiose. Under the optimal conditions, 6.9 g XOS, 40.3 g glucose, and 8.9 g xylose were produced from 100 g poplar.ConclusionsThe AC and HPAC pretreatment of poplar represented an efficient strategy to produce XOS and fermentable sugars with high yields. This two-step pretreatment was a recyclable benign and advantageous scheme for biorefinery of the poplar into XOS and monosaccharides.

The purpose of the present study was the production of xylooligosaccharides (XOS) from the sugarcane bagasse and evaluation of its prebiotic function in a synbiotic pomegranate juice. The XOS production was done in two steps: optimization of alkaline hydrogen peroxide extraction of xylan followed by the enzyme hydrolysis method by the response surface methodology based on the central composite design (CCD). The structural properties of the extracted xylan were also evaluated by HPLC and FT-IR analyses. The mixed xylooligosaccharides for protecting the prebiotic function of Bifidobacterium animalis Bb-12 in a developed synbiotic pomegranate juice was evaluated. The optimized extraction conditions for xylan via the response surface methodology (RSM) were 5.63 % H2O2, 12.91 % NaOH, and 17.51 h and corresponding to relative yield of xylan at the tune of 95.84 %. The minimum concentration of xylose (3.034 mg/ml) and maximum yield of XOS (5.52 mg/ml) through RSM were achieved at the enzyme dose of 85 U/g, substrate concentration of 3%, and reaction time of 10 h. The generated XOS could increase the viability of the probiotics during 30 days of storage at 4 °C. The prebiotic production of XOS from xylan of bagasse via enzymatic hydrolysis is preferred for the pharmaceutical and food industry applications owing to food safety and consumer awareness. Enzymatic production of XOS could be a suitable solution for the protection of probiotic bacteria in the low acidic environment of pomegranate and other acidic juices or non-dairy synbiotic beverages.

Xylooligosaccharides production by crude microbial enzymes from agricultural waste without prior treatment and their potential application as nutraceuticals

Barley malt residue (BMR) was subjected to microwave-assisted enzymatic hydrolysis to evaluate its potential as a raw material to produce xylooligosaccharides (XOS) suitable for use as a prebiotic. The influent factors on XOS production, microwave power, exposure time, and xylanase dosage were ascertained with response surface methodology based on Box-Behnken design (BBD). The fitted models of XOS and xylose yields were in good agreement with the experimental results. Using a microwave power of 1235.1 W, a 6 min exposure time, and a xylanase concentration of 89.12 U/g substrate gave the highest yield of XOS: 208.05 mg/g substrate at 4 h of enzyme incubation time. Based on the product composition, BMR-XOS purification by Saccharomyces cerevisiae treatment was superior to the process of activated carbon adsorption and ethanol precipitation treatment and was selected for further experiments. Thin-Layer Chromatography (TLC) and high-performance liquid chromatography (HPLC) clearly elucidated the oligosaccharide compositions, and the result of Fourier Transform Infrared Spectroscopy (FTIR) confirms the molecular structure and sugar components of achieved BMR-XOS. In vitro fermentation of BMR-XOS obtained from this study by the selected probiotics, Lactococcus lactis TISTR 1401, Levicaseibacillus brevis FS 2.1, Lactobacillus casei TISTR 1463, showed similar prebiotic activity compared with the commercial XOS, galactooligosaccharides (GOS), xylose, and glucose (control). In conclusion, the present study was successful in establishing the use of barley malt residue for the extraction of xylan and XOS, which could be further used as a prebiotic.

Production and optimization of xylooligosaccharides from corncob by Bacillus aerophilus KGJ2 xylanase and its antioxidant potential

Microwave-assisted acid hydrolysis to produce xylooligosaccharides from sugarcane bagasse hemicelluloses

Partial enzymatic cell wall disruption of Oocystis sp. for simultaneous cultivation and extraction

Rice husk (RH) is the major agricultural waste obtained during rice hulling process, which can be a sustainable source of xylooligosaccharide (XOS). The current study deals with the production of XOS from Thai rice husk using alkaline pretreatment and enzyme hydrolysis method. The response surface methodology consisted of central composite design and Box–Behnken design was employed to achieve the maximum response in alkaline pretreatment and XOS production, respectively. The optimum conditions for alkaline pretreatment to recover maximum xylan yield were 12–18% of alkaline concentration, the temperature at 110–120 °C, and steaming time for 37.5–40 min. The FTIR results suggested that the extracted sample was the xylan fraction. The maximum XOS production of 17.35 ± 0.31 mg XOS per mL xylan was observed in the run conditions of 6.25 mg enzyme per g xylan, 9 h of incubation time, and 5% of xylan. The results revealed that the xylan extracted from RH by using an effective base couple with the steam application and the enzymatic hydrolysis help to maximize the yield of XOS, which can be further used in functional foods and dietary supplements.

Xylooligosaccharides production from a sugarcane biomass mixture: Effects of commercial enzyme combinations on bagasse/straw hydrolysis pretreated using different strategies.

Efficient production of xylooligosaccharides and fermentable sugars from corncob by propionic acid and enzymatic hydrolysis

One-step sodium bisulfate hydrolysis for efficient production of xylooligosaccharides from poplar

Xylanase production strain, Aspergillus carneus M34, which was isolated from soil by our laboratory, was used to study the growth condition for optimal xylanase production, extraction methods and enzyme characterization by solid state fermentation used coba husk and corn steep liquor for the medium. In addition, possibility of the crude enzyme degrading coba husk hemicellulose to produce xylooligosaccharides was evaluated. Solid-state was the better fermentation type to ferment coba husk for xylanase production of Aspergillus carneus M34. In one factor test, the better cultivation conditions as follows: inoculums size 106 spores g-wm-1, cultivation temperature 25℃, initial pH value of medium pH 8.0. For optimization of the cultivation conditions, central composite design and response surface methodology were practiced. The optimal cultivation conditions were 25.6℃ of cultivation temperature, initial pH value of medium pH 7.96, the predicted maximum xylanase activity under optimal conditions was 6,781 U gdm-1. This represented 3.9-fold gain in xylanase activity. The better extraction conditions as follows: extraction temperature 25℃, extraction time 1 hour, pH of extractive pH 5.0 ~ 6.0, Tween 80 concentration of extraction solution 0.1%. The test of crude enzyme degradation of coba husk hemicellulose. The optimal pH and temperature were pH 5.0 and 50 ~ 60℃, respectively. It also exhibited a good pH stability at range of pH 4.0 to 7.0. In respect to thermostability, the residual activity of xylanase activity was 80% at 50℃ for 70 min. The crude enzyme hydrolyzed product contented xylooligosaccharides. The predicted xylooligosaccharides yield pre kg coba husk were xylobiose 61 g, xylotriose 11 g and xylotetraose 22 g under 30 min reaction.

Xylanases produced by microorganisms hydrolyze xylan, into xylose or xylooligosaccharides (XOS). Xylan is an abundant noncellulosic polysaccharide found in the plant biomass. The enzyme is of great practical importance for the conversion of xylan containing agricultural residues into XOS for use as prebiotics. A Bacillus subtilis strain DFR40 a generally recognized as safe (GRAS) organism was found to produce extracellular xylanase in a growth medium containing wheat bran, mineral salts, peptone, and yeast extract at pH 7.0. The optimum activity of the enzyme was around 100°C and pH 9.0 with stability over a broad range of pH (7.0–12.0) displaying enzyme stability of more than 70% even after pre-incubation at 55–85°C for 30 min. The enzyme hydrolyzed wheat bran into short chain XOS as revealed by TLC, HPLC, FT-IR, and NMR analysis. Practical applications The thermostable and alkali resistant characteristics of extracted xylanase along with ability to hydrolyze wheat bran for the production of xylooligosaccharides (XOS), for use as prebiotic ingredients in food, are relevant in the present health conscious worldwide scenario. XOS are emerging class of prebiotics with thermal resistance up to 100°C, and are suitable for incorporating into thermally processed food products with extended shelf life. The XOS preparation was also found suitable suggesting the prebiotic nature of XOS on known probiotic bacterial strains. The study also indicates a valuable application for wheat bran, a cheap agro residue for further cost effective scale up of XOS production. The xylanase produced is of significance as the producing bacterium is a GRAS organism for further scale-up of the processes of enzyme and XOS production.

Xylooligosaccharides (XOS) are non-digestible and fermentable oligomers that stand out for their efficient production by enzymatic hydrolysis and beneficial effects on human health. This study aimed to investigate the influence of the main reaction parameters of the beechwood xylan hydrolysis using crude xylanase from Aureobasidium pullulans CCT 1261, thus achieving the maximum XOS production. The effects of temperature (40 to 50°C), reaction time (12 to 48h), type of agitation, substrate concentration (1 to 6%, w/v), xylanase loading (100 to 300 U/g xylan), and pH (4.0 to 6.0) on the XOS production were fully evaluated. The most suitable conditions for XOS production included orbital shaking of 180rpm, 40°C, and 24h of reaction. High contents of total XOS (10.1mg/mL) and XOS with degree of polymerization (DP) of 2-3 (9.7mg/mL), besides to a high percentage of XOS (99.1%), were obtained at 6% (w/v) of beechwood xylan, xylanase loading of 260 U/g xylan, and pH 6.0. The establishment of the best hydrolysis conditions allowed increasing both the content of total XOS 1.5-fold and the percentage of XOS by 9.4%, when compared to the initial production (6.7mg/mL and 89.7%, respectively). Thus, this study established an efficient enzymatic hydrolysis process that results in a hydrolysate containing XOS with potential prebiotic character (i.e., rich in XOS with DP 2-3) and low xylose amounts.