Carvalho 2013 XOS Review

Food Research International 51 (2013) 75–85Contents lists available at SciVerse ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres Review Xylo-oligosaccharides from lignocellulosic materials: Chemical structure, health benefits and production by chemical and enzymatic hydrolysis Ana Flávia Azevedo Carvalho a,b,⁎, Pedro de Oliva Neto b, Douglas Fernandes da Silva b, Gláucia Maria Pastore a a b Department of Food Science, School of Food Engineering, State University of Campinas (UNICAMP), Rua Monteiro Lobato, 80, ZIP code 13083-862, Campinas, SP, Brazil Department of Biological Sciences, School of Science and Letters, São Paulo State University (UNESP), Rua Dom Antonio, 2100, ZIP code 19806-380, Assis, SP, Brazil a r t i c l e i n f o Article history: Received 27 June 2012 Accepted 20 November 2012 Keywords: Lignocellulosic materials Chemical and enzymatic hydrolysis Xylanases Xylo-oligosaccharides a b s t r a c t Currently, there is worldwide interest in the technological use of agro-industrial residues as a renewable source of food and biofuels. Lignocellulosic materials (LCMs) are a rich source of cellulose and hemicellulose. Hemicellulose is rich in xylan, a polysaccharide used to develop technology for producing alcohol, xylose, xylitol and xylo-oligosaccharides (XOSs). The XOSs are unusual oligosaccharides whose main constituent is xylose linked by β 1–4 bonds. The XOS applications described in this paper highlight that they are considered soluble dietary fibers that have prebiotic activity, favoring the improvement of bowel functions and immune function and having antimicrobial and other health benefits. These effects open a new perspective on potential applications for animal production and human consumption. The raw materials that are rich in hemicellulose include sugar cane bagasse, corncobs, rice husks, olive pits, barley straw, tobacco stalk, cotton stalk, sunflower stalk and wheat straw. The XOS-yielding treatments that have been studied include acid hydrolysis, alkaline hydrolysis, auto-hydrolysis and enzymatic hydrolysis, but the breaking of bonds present in these compounds is relatively difficult and costly, thus limiting the production of XOS. To obviate this limitation, a thorough evaluation of the most convenient methods and the opportunities for innovation in this area is needed. Another challenge is the screening and taxonomy of microorganisms that produce the xylanolytic complex and enzymes and reaction mechanisms involved. Among the standing out microorganisms involved in lignocellulose degradation are Trichoderma harzianum, Cellulosimicrobium cellulans, Penicillium janczewskii, Penicillium echinulatu, Trichoderma reesei and Aspergillus awamori. The enzyme complex predominantly comprises endoxylanase and enzymes that remove hemicellulose side groups such as the acetyl group. The complex has low β-xylosidase activities because β-xylosidase stimulates the production of xylose instead of XOS; xylose, in turn, inhibits the enzymes that produce XOS. The enzymatic conversion of xylan in XOS is the preferred route for the food industries because of problems associated with chemical technologies (e.g., acid hydrolysis) due to the release of toxic and undesired products, such as furfural. The improvement of the bioprocess for XOS production and its benefits for several applications are discussed in this study. © 2012 Elsevier Ltd. All rights reserved. Contents 1. 2. 3. 4. 5. Introduction . . . . . . . . . . . . . . . . . . . . . . Chemical structure of xylo-oligosaccharides . . . . . . . . Health benefits of xylo-oligosaccharides . . . . . . . . . Soluble fibers as substitutes for antibiotics in feed . . . . . Technologies for obtaining xylo-oligosaccharides . . . . . 5.1. Pretreatments for xylan extraction . . . . . . . . . 5.1.1. Autohydrolysis . . . . . . . . . . . . . . 5.1.2. Alkaline and acid pretreatments . . . . . . 5.2. Enzymatic treatment of pre-hydrolyzed LCM residues 5.2.1. Xylanases . . . . . . . . . . . . . . . . 5.3. Enzymatic technology for XOS production . . . . . . . . . . . . . . . . . . . . . and . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XOS production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 76 77 77 78 78 78 79 80 80 82 ⁎ Corresponding author at: São Paulo State University (UNESP), Rua Dom Antonio, 2100, ZIP code 19806-380, Assis, SP, Brazil. Tel./fax: +55 1833025848x5716. E-mail addresses: [email protected] (A.F.A. Carvalho), [email protected] (P.O. Neto), [email protected] (D.F. da Silva), [email protected] (G.M. Pastore). 0963-9969/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodres.2012.11.021 the XOSs are stable over a wide range of pHs (2. . Chemical structure of xylo-oligosaccharides XOSs are oligosaccharides commercialized as a white powder containing two to ten xylose molecules linked by β 1–4 bonds (Fig. . . . . XOS is a promising oligosaccharide class that stimulates increased levels of bifidobacteria to a greater extent than does FOS (Tuohy. . . Wang. & Montané. . 2002. fructooligosaccharides (FOS) it is related that in a 10% solution of pH 3. . Rodrigues et al. the total bagasse generated in this season will be approximately 80. Some prebiotics such as fructo-oligosaccharides and mannan oligosaccharides are currently widely used in feed (for pigs. beginning in 2006. Samanta.. .0).5– 8. . . . 1998). & Rastall. . . . . which includes a chemical pretreatment. 2000). temperature and pH). . the bioprocess parameters (such as reaction time. or when subjected to prolonged storage under room conditions. . . . Brück. 2008. Most oligosaccharides can be hydrolyzed. Some sugar mills also use cane bagasse to co-generate electricity. . . In other LCM residues such as tobacco stalk. some cane bagasse remains that can be used for other purposes. . . Xu. represented by 1-arabino-(4-0-methyl-D-glucurono)-D-xylan. . Saha. or the enzyme can be produced in situ via fermentation. 2009). 1999). . . Gibson.. 2000. . Gullón. XOSs are produced by hydrolyzing xylan. .4% lignin.. . XOSs are oligomers containing two to ten xylose molecules linked by β 1–4 bonds (Mäkeläinen et al. . . & Soccol. . The oligosaccharide production by enzymatic processes is influenced by some critical factors. Erdogan. The biochemical characterization of XOS-producing microorganisms. ring forms and anomeric configurations. Senani. . when treated at high temperatures for short time periods. . . aiming to contribute to improvements in XOS production technology. . . and temperatures up to 100 °C. Moreno. . & Silva. generating steam. . . . linkages. Ebringerová. Nigam.1% acid detergent fiber. . & Bostanci. 83 1. XOS stabilities can differ greatly depending on the types of oligosaccharide and sugar residues. the search for new molecules with powerful prebiotic activity is essential. ..F. . 2005). . Jones.. . . . 2007). 2007. . et al. Rouzaud. . . . 83 References .8% xylan. . especially to produce products with high added value. . 2012). even the relatively low pH value of gastric juice. Commercialized as a white powder. Moure.. The increase in food production must be sustainable and avoid the deforestation of new areas that are currently occupied by forests. . . . Although there are multiple treatments for xylan extraction. sunflower stalk and wheat stalk. . 9. Tamashiro. . . . . XOS production from LCM is not simple or economical because it depends on two treatment steps. After two days at 30 °C less than 50% is hydrolyzed (Voragen. Santos. Rycroft. arabinose. chickens. . Nevertheless. Cane bagasse is currently used in sugar mills for burning in boilers. . the free enzyme can be produced and used in mixtures with the reaction substrate. 2010. 83 Acknowledgments . Pandey. virulent strains of pathogens are increasing. . . . Vázquez et al. . . . XOSs are considered non-digestible oligosaccharides (NDOs). . . 2006. . its microorganism source and the stability and activity of the xylanase at different pHs and temperatures. lignin. However. & Milagres. . & Parajó.. Sugar cane bagasse has 24–29% hemicellulose. 75. Therefore. . 2005) or other oligosaccharides (Rycroft et al. & Gibson. . . . . . The type and concentration of substrate. Considering only the sugar and ethanol in Brazil. Converti. . 2008). . Generally. waxes and other compounds (Brienzo et al. heating cane juice and operating the mills. . Yang. . 2012). . . . . Xylan is also a heteropolysaccharide with a backbone formed by xylose homopolymer subunits (Nabarlatz.9% neutral detergent fiber and 37. . .. . 33–44% cellulose and 20–29% lignins (Akpinar.b). . . . suggest the presence of glucan 31–35%. .0. . & Parajó. but molecules with degree of polymerization (DP) ≤ 20 have been considered XOS (Mäkeläinen et al. 2002.A. . . one of the most important LCMs studied for xylo-oligosaccharides (XOS) production. . Dominguez. This is an advantage compared with other NDOs such as FOS and inulin (Bhat. . . research into the use of agro-industrial residues for food production should be intensified because these wastes are underutilized and billions of tons are discarded annually. Rivero-Urgell & Santamaria-Orleans. Therefore. Domínguez. . .5 less than 10% is hydrolyzed after heat treatments of 5 min at 45 °C or 60 min at 70 °C. . . . . . . & Pastore. . . 2002. . Rodrigues et al. . . . one of the greatest challenges is to increase the production of healthy and economically affordable foods that are available for a large proportion of the world's population. productivity and type of oligosaccharide produced depend on the type of enzyme. non-cariogenic in humans and have important biological properties. . . 2. thus saving energy in the process. . . Carvalho et al. . immobilized and recycled. . . . . there has been increasing interest in new prebiotics such as XOS. Samanta. . Reports on the chemical composition of corncobs. . . . . . . . 2001. For example. . Soccol. galactose. Rastall & Maitin. . . Rivaldi. (2012) found similar results for corncobs: 27. . the European Union banned the use of growth promoting antibiotics (GPAs) in farming (Falcão et al. . 1998). Lignocellulosic materials (LCM) represent the most abundant organic residues in the world. Wallace. Oliveira. . .. At 135 kg of dried bagasse per ton of crushed cane (Brienzo. They are used as dietary sweeteners in low-calorie diet foods and for consumption by individuals with diabetes (Choque Delgado. The pretreatment methods discussed in this paper are autohydrolysis and acid and alkaline hydrolysis. 2001. Conclusion . . & Rastall. cotton stalk. developing an efficient and economical xylanase production bioprocess for use in XOS production is necessary. . . . the main chemical composition is 19–21% xylan.5 billion tons.7% cellulose. Siqueira. Vázquez et al. / Food Research International 51 (2013) 75–85 6. . Song & Wei. . 2000). . 2010). .. .76 A. . . 2007. . . & Yang. 2009a. . . . 2001). The second step includes the xylanase enzymatic reaction or the acid hydrolysis of xylan. . the type and conditions of pretreatment for xylan extraction and downstream processes are considered in this study. . . . . minerals. as well as cellulose. . 2010). . Senani. . including the emergent prebiotic XOS (Olano-Martin. . Junior. . 1). 2003. . lignin 10–14% and a high xylan content (30–35%) (Garrote. Furthermore. resulting in the loss of nutritional and physicochemical properties at pH b 4. 2010. cattle and pets). .. . Tan et al. their modes of action and their xylanase activities are included in the present review. 2010. . 2009.6 billion tons (CONAB. 2010. . & Bom. . Introduction Currently. Domínguez. Sarrouh. . . . Gottschalk. . et al. . . Due to the overuse of antibiotics. . . The first step is the xylan extraction from LCM. . Consequently. 38. . . & Parajó. the estimated production of sugar cane for the 2012/13 season will be 596. 2011. Gibson. . there is no consensus favorite among them. . In this regard. . and hexoses are more strongly linked than pentoses. β-linkages are stronger than α-linkages. replacing the use of antibiotic growth promoters (AGPs). . . Hemicellulose is a heteropolysaccharide with xylan as the major carbohydrate and mainly comprises polymers of xylose. The yield. and there is the possibility of antibiotic residues in meat. In recent years. mannose and glucose (Garrote. Vázquez et al. 2000). leading to widespread adoption of AGP inclusion in feeds. Health benefits of xylo-oligosaccharides XOS are not digested by humans because the human body lacks the enzymes required to hydrolyze the β-links. 2007). 2007. Nabarlatz et al. (2000) Vázquez et al. calcium absorption and lipid metabolism.. (2008). not only to treat or prevent infection in farm animals but also for low dose-long term administration. 1. XOSs with fewer than four monomer units are important for prebiotic applications because they promote the proliferation of bifidobacteria. 2007). XOS provides beneficial effects on: skin. XOS can improve the microbiota increasing the presence of beneficial bacteria. 2000)... to help animals gain weight more quickly and increase the productivity and yield in animal production. 2007).g. that inhibit the growth of pathogenic and putrefactive bacteria (Mussatto & Mancilha. 2007. particularly Bifidobacterium. including improvement in bowel function. Antibiotics have been widely used in animal production. Therefore. anti-oxidant activity.A. Improvements in bowel function and calcium absorption. 2000).. However. (2009) Decrease in the number of pathogenic and putrefactive bacteria. 2009). XOSs provide health benefits as the active ingredients in functional foods. usually given in feed. In recent decades. Wang et al.. the European Union banned the use of growth promoting antibiotics (GPAs) in farming (Falcão et al. Grootaert et al. including stability at acidic pH. / Food Research International 51 (2013) 75–85 HO O X1 = xylose OH HO 77 OH HO HO OH X2 = xylobiose O HO O OH O OH HO HO OH O O O HO O n O OH HO OH OH n = 1: n = 2: n = 3: n = 4: n = 5: X3 = xylotriose X4 = xylotetraose X5 = xylopentaose X6 = xylohexaose X7 = xyloheptaose Fig. and they are considered important prebiotics. Soluble fibers as substitutes for antibiotics in feed The use of antibiotic growth promoters (AGPs) in animal production began half a century ago when residues of chlortetracycline production were added to chicken feed. 2007. The addition of XOS to food adds physiological properties beneficial for the body. The biological activity of a XOS depends on its molecular weight distribution (Hughes et al. XOS Benefits References Modulation of the colon microbiota increasing the number of bifidobacteria and Lactobacillus. Van Haren. These residues were added to serve as a source of vitamin B12. which are considered as beneficial microorganisms in the human intestine (Gullón et al. non-toxicity and other properties that have yet to be studied (Vázquez et al. Vázquez et al. 2000). (2007). (2000) . reduction of osteoporosis).. immunological action. Wallace. XOS also have favorable technological features. This property allows XOSs to be used as dietary sweeteners for low-calorie diet foods and for consumption by individuals with diabetes (Choque Delgado et al. Biological effects at low doses. 2007. In addition. Vázquez et al. heat resistance. Van Laere. and Voragen (2000) Mussatto and Mancilha (2007) Blaut (2002).. the prevention of dental caries. Wang et al. anti-inflammatory and antiallergic action. immunological system. Carvalho et al. anti-oxidant. Mannan oligosaccharides (MOS) act mainly by preventing colonization more than by stimulating beneficial microorganisms. Consequently. 1999). Growth of health-promoting bacteria in the intestinal tract leading to the production of short chain fatty acids. overuse of antibiotics encourages resistance and the production of more virulent strains of pathogens. and they show several health benefits (Table 1)..A.. Moure et al.. 3. Grootaert et al. 2011. Hartemink. 2007). This observation was quickly extended to other antibiotics and other animal species. beginning in 2006. antiinflammatory effects and antiallergic activities (Aachary & Prapulla. they are classified as NDOs. (2009) Aachary and Prapulla (2009). (2006). 2001. as both therapeutics and growth promoting agents (Falcão et al. These components may be present in food or as added industrial products (Nabarlatz et al.. 2007). NDOs are noncariogenic because they are not utilized by mouth microbiota (Vázquez et al. Protection against cardiovascular disease and reduction of the risk of colon cancer due to the formation of these acids. (2007). low calorie content. Low calorie. considerable amounts of antibiotics have been used in animal production. blood.. Wang et al. but they caused a growth stimulation that was far too large to be explained as only a vitamin effect (Brezoen.. 2008).. prevention of dental caries. & Hanekamp. Bosveld. 4. Many pathogens have fimbriae that Table 1 Xylo-oligosaccharide benefits for the healthy human. Rivero-Urgell & Santamaria-Orleans. the ability to achieve significant biological effects at low daily doses. 2009). Effects related to skin and blood. Gullón et al. protection against cardiovascular disease and reduction in the risk of colon cancer due to the formation of short-chain fatty acids (Grootaert et al. Some studies indicate that 4 g of XOS per day for 3 weeks improved the intestinal microbiota among people who are above 65 years old (Chung et al.. Schematic structure of xylose and xylo-oligosaccharides.F. Schols. so they are considered prebiotics and soluble fiber because they are not degraded in the stomach and reach the large intestine intact. which cause beneficial effects for metabolism (e. 2002).. 2006).. 2007).. 2004. 2001).g. 2008. lactosucrose.g. the products released by autohydrolysis require extra treatment. possibly as a result of the reduction in microbial counts. (Gill. 2002. On the other hand. sugars and aldehydes. 2005). They were evaluated in a medium for promoting the growth of Bifidobacterium adolescentis CECT 5781. waxes and pectin) and make the later XOS-producing steps easier (Brienzo et al.. by groups in Europe (Tuohy et al. which includes soyoligosaccharides. Pinheiro et al. USA) or 1% crude XOS produced by the authors. and Wolf (1997) fed rats a 6% (w/w) diet of XOS and reported a significant increase in both cecal and fecal bifidobacteria. 2010. reported that MOS increased the length of ileal villi. 2008. Pretreatments for xylan extraction Various pretreatments have been used for the complete extraction of hemicellulose to make xylan for enzymatic reactions. Bifidobacterium longum CECT 4503.. These bacteria satisfied the major probiotic criteria (Senani et al. glucooligosaccharides and pecticoligosaccharides (Olano-Martin et al. & Cross. adolescentis was 77% in 24 h of culture and the highest percentage of consume corresponded to xylotriose (90%). Autohydrolysis Autohydrolysis involves the deacetylation of xylan by the thermal hydrolysis of hemicellulose to produce acetic acid (Garrote et al. Wu. 2005) and other oligosaccharides (Rycroft et al. 2002. 2002. Castillo. 2001). L. Zhang. if they bind to mannose residues of MOS they will not attach to the mucosa. Japan and the United States. the LCM can be separated into two fractions. (2001) showed that XOS as the sole carbon source resulted in a significant increase in bifidobacterial numbers after 24 h (Sharp. The bifidogenic nature of XOS has been confirmed in rats. Lin... 2001. which they also detected.40 h −1. acid or alkaline pre-hydrolysis and enzymatic hydrolysis. All of them grew on XOS medium. Fructooligosaccharides. 2001). and others. XOS produced by autohydrolysis contains a significant proportion of compounds with a high degree of polymerization (Nabarlatz et al. and L. The authors believe these quantitative differences may be due to the crude preparation of XOS compared against pure FOS. Moura et al. enzymatic or acid hydrolysis (Moure et al.F... (2012) studied the “in vitro” effect of crude XOS (from corncob xylan) on the growth of the following probiotics responsible for improvement of digestibility in ruminants gut: Enterococcus fecalis CCD10. 1998. anti-infective activities of prebiotics have been studied in mice. 2006). Falcão. The bacterial growth was higher with E. fecalis. Other studies have been showed the XOS ability in the growth of some beneficial bacteria. 0.. thereby requiring further purification (Zhu. including the production of cellulose pulp (Caparrós. hygienic conditions and the nature and amount of the prebiotic added to feed. working with rabbits. The percentage of total XOS by B. 2006. it is possible that prebiotics show benefits in long-living beings. 2007) and fermentable sugars or fuel (Yáñez et al. Li. according to Falcão et al. Fahey. such as soluble oligosaccharides. & Gao.g.. Samanta. Fishbain. Shu et al. However.37. furfural. 2004. LeBlanc. Fujikawa. Okazaki.. The precipitated solids are high in cellulose and lignin. Rycroft et al. 2001). Technologies for obtaining xylo-oligosaccharides 5. et al. Mourão et al. but do not in short-lived species. including Salmonella. XOSs were obtained by autohydrolysis of rice husk and purified by nanofiltration and ion exchange processing. e.. However.. (2006). Crude XOSs were capable to growth probiotic organisms as compared to either control or 1% glucose. a much wider range of emergent prebiotics exists. lactulose and galactooligosaccharides are well established as prebiotics in Europe.. 2005). 2009). 2009. The soluble and liquid phase is rich in hemicellulose... Escherichia coli and Listeria monocytogenes.. . Ebersbach. Silva et al.A. López. but the specific growth rate of B. and Frøkiær (2012). XOS can be effectively fermented by bifidobacteria (Jaskari et al. Enterococcus faecium TCD3. In several animals trials. & Spring. & Perdigon. In addition. isomalto-oligosaccharides. MOS performances were comparable to those obtained with AGPs (Fonseca.. 2005). infantis and B breve (0. After prehydrolysis. 2000. This inconsistency can be explained by differences in experimental protocols. Moreover. Campbell. faecium. & Macfarlane. The current methods used for pretreatments are autohydrolysis. 2006). monosaccharides. Mourão et al. followed by E. the influence of FOS on the growth stimulation of probiotics was higher than either XOS or glucose. This treatment can be used as a first step in the fractionation processes for LCM. and they can be separated for further processing to enable a variety of possible applications. However.. When LCM containing xylan is submitted to autohydrolysis under mild operating conditions. Kabel et al. The organisms were grown in MRS broth supplemented with 1% (w/v) glucose or 1% FOS (Sigma. Kocher. Vázquez et al. / Food Research International 51 (2013) 75–85 specifically attach to the mannose residues of intestinal cell receptors.. Rastall & Maitin. respectively). According to review of Otieno and Ahring (2012a) XOSs have been recently regarded as emerging prebiotics that may present the same or more desirable properties than the more established oligosaccharides... xylotetraose (83%) and xylopentaose (71%) (Gullón et al. The products obtained from LCM by this process contain a variety of undesirable components such as lignin. such as rabbits. 1999. Furthermore.. The growth of Lactobacillus brevis and their capability to utilize XOS from corncob as carbon and energy source was proved (Moura et al..30 and 0. 2007). faecium indicated that this bacteria possessed enzymes for hydrolyzing the glycosidic bonds present in the XOS. Bifidobacterium infantis CECT 4551 and Bifidobacterium breve CECT 4839. Much of the supportive evidence for these new prebiotics has been generated by researchers in Japan and. 2008). Before starting the pretreatment. autohydrolysis requires specialized equipment that needs to be operated at high temperatures (Zhu et al. gentiooligosaccharides. there is a lack of consistency in the results obtained with prebiotics. e. (2007).. xylo-oligosaccharides. Carvalho et al. viridiscens. longum. Truusalu et al. The pretreatments include thermal and chemical methods (Aachary & Prapulla. the number of animals. Several studies have shown a protective effect of prebiotics in animals infected with typical food borne bacteria. The XOS diet stimulated the increase in bifidobacteria levels to a greater extent than did FOS (Tuohy et al. 5.1. 5. and it can be decomposed into valuable products. followed by xylobiose (84%). Rycroft et al.. Mourão et al.1. 2008). 2009). rats. Senani. pigs. increasingly. inulin. the raw material can be prepared by washing with ethanol or ethyl acetate to remove impurities and other compounds (e. Rutherfurd. (2006) confirmed that the amount of prebiotics required for efficient animal production could limit its use due to high cost.. Vázquez et al.78 A. & Díaz. adolescentis (0.. alcohols and ketones can be used in the recovery of soluble xylan or to concentrate the released XOS (Akpinar et al. xylo-oligosaccharides (XOSs) are the main products of the hydrolysis of hemicellulose. broilers. According to Licht. Lactobacilllus maltromicus MTCC108 and Lactobacillus viridiscens NCIM2167. Vieira et al. 2006). but otherwise. 1990). contributed to diarrhea prevention. Ariza. hamsters and guinea pigs and generally showed that prebiotics improved host resistance to bacterial infections. 2004). 2009b. and increased animal survival.58 h −1) was higher than the ones determined for B. decreased microbial colonization and translocation of the pathogen.1. The enhanced growth of E. Shu. Garrote. & Matsumoto. XOS shows an ability for suppressing the growth of Clostridium and bacteriostatic action against Vibrio anguillarum (Izumi & Azumi. maltromicus. B. To obtain XOS with a degree of polymerization of 2–6 xylose units. 2007. The content (19. The alkaline pre-hydrolysis has the disadvantage of not preserving the acetyl groups present in xylan (Nabarlatz et al. Although the acid concentration used was low. 2009).. the best procedure is to use alkaline and thermal hydrolysis. sunflower stalk (12. & Yilmaz. 2009.7 mg/ml). 2). two of the major disadvantages of acid hydrolysis are the production of considerably high amounts of monosaccharides and the formation of undesirable toxic furfural (Akpinar et al.F.90% H2SO4) on XOS production from xylans of tobacco stalk (TSX).6%) and wheat straw (10. The evaluation of pretreatment methods is based on two criteria: xylan content after pretreatment and quantities of XOS produced under certain standard conditions. since there was an increase of 18..06 mg/ ml).22%–4. with the acid pretreatment followed by cooking. These last products make purification steps more difficult and expensive in addition to decrease in the XOS yield.9% sulfuric acid at 100 °C produced mainly monosaccharides rather than oligosaccharides. The effect of different acid concentrations (1. & Su. Oliva-Neto. Erdogan. 79 the reaction time was long. These results justify the use of pretreatment before xylanase reaction of crude xylan.4%) was slightly lower than from acid hydrolysis. and probably allowed the degradation of xylan to xylose under these conditions. if the xylan extraction yields were similar (approximately 40%). Alkaline and acid pretreatments The exposure of hemicellulose to enzymatic hydrolysis must frequently be preceded by pretreatment with acid or alkali (Fig.5%) (Brienzo et al. When the alkaline. sunflower stalk (SSX) and wheat stalk (WSX) was evaluated (Akpinar et al.. However even under these condition the XOS yield was low for tobacco (13%). cotton stalk (7. alkaline pretreatment with hydrogen peroxide in sugar cane bagasse showed good efficiency in delignification and hemicellulose solubilization. 2010).4% to 83. the XOS yields and concentrations.. The alkaline prehydrolysis showed the best performance in exposing xylan to the action of endoxylanases. respectively.2%) using rapid thermo-acid process (0. Different methods of corncob pretreatment were evaluated to make the xylan more accessible to the xylanase reaction and for the complete extraction of the xylan.. Sun.. These results showed the importance of higher alkali concentrations in hydrolysis. 2012a. were 89% (2. & Pastore. The rapid thermo-acid treatment of sugarcane bagasse seems to be also more interesting for the XOS yield (92%) when compared to the yield of 39–40% by enzymatic method (Brienzo et al.5% to 63. The xylan extraction yield from raw corncob (without any pretreatment) is about was 31. 2009b). acid and pressure pretreatments were used. The major impediment of the acid treatment is the production of toxic components (furfural and HMF) that require a greater degree of purification. Vázquez et al. Bakir.9%) when it was compared with enzymatic hydrolysis (22. Reducing sugar production rates increased with time and acid concentration.2%). 2010. the best pretreatment according to the XOS yield was alkaline (Aachary & Prapulla. these extractions must be mild to limit the amount of xylose released by the acid treatment and avoid or decrease the resulting corrosion and pollution. 2005). . 2004). The XOS yield from enzymatic hydrolysis using xylan extracted from tobacco stalk by alkaline pretreatment (11.1.5% (for sodium hydroxide). which may limited the water solubility of XOS (Nabarlatz et al.5%). 2010).8. 81% (5. 2007). These last pretreatments were superior to an acid process since the XOS yield was considerably lower (52%) (Aachary & Prapulla. When the alkaline. acid (0. these yields increased to 40. Experiments carried out with corncob demonstrated that acid pretreatment alone did not alter the xylan–lignin complex but the subsequent baking did modify this structure. resulting in a high yield of XOS (Akpinar. More recently.9%.1% H2SO4 at 145 °C for 1 h).b). Furthermore. 39.7%) and quality of XOS (70% X2 to X4) from cane bagasse was also interesting and xylose content was not high (5. However. Therefore. Some alternative chemical pretreatments and acid or enzymatic treatments for XOS production from lignocellulosic residues.6% in xylan extraction yield. The type and chemical structure of the substrate and the enzyme specificity are important factors in the enzymatic hydrolysis of xylan to produce XOS.01 M H2SO4 at 60 °C in 12 h) and pressure steam cooked (135 °C/30 min) pretreatments were compared using the reaction of xylan extracted by a commercial xylanase (Table 2). The best conditions for acid hydrolysis were 2. Carvalho et al. However. An extraction from corncob using 2% and 12% alkali and steam hydrolysis improved the xylan recovery from12. respectively.. 2009).A.. 2009).0%. 2. Acid and alkaline pretreatments of corncob were compared. 2010).2% (for potassium hydroxide) and 14.2 and 40. If the importance of pretreatment and the limitation of acid hydrolysis is to be proven. allowing the removal of lignin and production of XOS after enzymatic hydrolysis (Yang et al. However. / Food Research International 51 (2013) 75–85 5. Xylan obtained by this Fig.9%) and cane bagasse (92.A..2. respectively (Aachary & Prapulla. preserving its chemical structure (Brienzo et al.1%). Sun. 2005). Carvalho. with increased xylan recovery at increased alkali levels. cotton stalk (CSX).4. Otieno and Ahring (2012b) obtained high yield of XOS from switchgrass (Panicum virgatum — 84.45% H2SO4 in 30 min of reaction time at 100 °C. the first treatment is simpler in the hydrolysis step. Sun. morning light (Miscanthus sinensis — 64.8 mg/ml) and 77% (3. A.1 55.8 – – – 12.4% (0. Ruminococus.8 U/ml) (Oliveira et al. 1999). the microorganisms Aspergillus flavus. 1999.1 86. (2012) Samanta. followed by oat bran (5.1 2.2.9 86. 2010). The higher levels of xylanase (547. The fungi produce xylanases..0 U/ml) and corn straw (23.0 17. oat hulls and sugar cane bagasse with the liquid fraction used in the production of xylanases by Penicillium janthinellum (Christov et al. janthinellum Trichoderma reesei RUT-C30 Aspergillus awamori 2B. Corncob Alkali pretreat. Streptomycetes. Reference Reaction time XOS production XOS Treatment XOS production Xylan yield (%) production extraction for XOS (g/l) production yield (%) Enzymatic hydrolysis – Enzymatic hydrolysis Enzymatic hydrolysis Enzymatic hydrolysis enzymatic hydrolysis Enzymatic hydrolysis Enzymatic hydrolysis Acid hydrolysis Enzymatic hydrolysis Enzymatic hydrolysis Acid hydrolysis Acid hydrolysis Acid hydrolysis Enzymatic hydrolysis Enzymatic hydrolysis 40. (2005) Botella et al. 2007). Wang.79 0. Srinivasan.1. Xylanases 5.6 20.7 3.4 U/ml). (2009b) Chapla. & Rele.0 15. and Milagres (2010) Samanta..1 U/ml) (Terrasan et al. Senani. 1992. 1992). and Shah (2012) Brienzo. Corncob Acid pretreat. Guez. (2010) Gottschalk et al.4 68.5% (0.0 24 h 24 h 24 h 24 h 24 h 24 h 24 h 24 h 30 min 8h 96 h 15 min 30 min 60 min 14 h 8h method was submitted to 0. Penicillium oxalicum and Trichoderma harzianum were common among isolates from the three substrates.8 2. and Saini (2010) Christopher et al. (2012) Samanta.0 37.8 1.0 1. barley grain (4. Sunflower stalk Alkali pretreat. Strains Xylanase activity Substrate Fermentation Reference Cellulosimicrobium cellulans Penicillium janczewskii P.5 83. et al. Jayapal.. Corncob Steam cooked Palm oil Autohydrolysis Tobacco stalk Alkali pretreat.9 13. and Xu (2011) Jayapal et al. Tobacco stalk Alkali pretreat. Clostridium.8 – 5. Enzymatic treatment of pre-hydrolyzed LCM residues and XOS production 5.0 – 21. (2006) Gottschalk et al. oats and residues from a bleaching effluent were compared. (2006) Oliveira et al.9 21. awamori Malbranchea flava MTCC 4889 Thermomyces lanuginosus ATCC 46882 0. the agro-industrial wastes rice straw.8 2. Senani.. Fusarium. The optimum conditions for the maximum yield of xylanases by T. corncobs.0 52. According to Abdel-Sater and El-Said (2001). Cane bagasse Alkali pretreat. Penicillium corylophilum. Penicillium chrysogenum. LCM residue Pretreatment xylan extraction Corncob Alkali pretreat..7 5. Triploid Populus tomentosa Alkali pretreat.000 U/g 5098 U/g Cane bagasse Wheat bran Oat bran Cane bagasse Pretreated corncob Pretreated cane bagasse Pretreated cane bagasse Pretreated cane bagasse Grape marc Wheat bran Rice straw Cellulose bagasse SmF SmF SmF SmF SmF SmF SmF SmF SSF SSF SSF SSF Song and Wei (2010) Terrasan et al. Dutta-Choudhary. Corncob Alkali pretreat. pretreatments for xylan extraction. harzianum (50. Martin. Pandit. Table 3 Fungal producers of xylanases and enzymatic activities on different substrates and fermentation process. Song. Microorganisms that produce of xylanases and substrates. awamori A. Noor.8 3.5 – 85.5 83. In Table 3.1. Phanerochaetes.6 U/ml) were 8 days of incubation at 35 °C in submerged fermentation (SmF) using starch and maltose as the sole carbon substrates. 2012a. SSF: solid state fermentation. but they usually co-secrete cellulases that can adversely affect the quality and purity of the product (Balakrishnan.2.65 mg/ml).F. and different treatments for XOS production. Pretreatments were performed using acidic residues of cassava hulls.8 U/ml).5 – 6. 82. 2012).6% (0. followed by bagasse (23. including Aspergillus. Chadha. & Balakrishnan.0 77. Corncob Alkali pretreat. et al. et al. Xylanases are produced by a variety of organisms. Cane bagasse Alkali pretreat.79 mg/ml) and 68. respectively (Samanta.. using various industrial residues (Bastawde.9 60. but there are some residues and microorganisms that stand out.b. substrates and different bioprocess conditions show a wide range of xylanase production in the literature. Among these species. The corncob (55. 5. (2010) Terrasan et al. Szakacs. (2010) Terrasan et al. 93% of the isolates 81. Carvalho et al.4 5. Carvalho et al.0 83. a study using the SmF of Penicillium janczewskii indicated that wheat bran was the best inducer (15.4 100 U/g 15. et al. (2005) SmF: submerged fermentation.3 23.4 U/ml) were reached when the medium with corncob was inoculated with Aspergillus foetidus ATCC 14916 (Christov et al. (2009a) Akpinar et al.3 U/ml) and oat hulls (54..5 36. (2010) Oliveira et al. corncob (5. (2012) Yang.1.8 39. Gomes.2.2 40. 1999). some strains of fungi that produce xylanases using different substrates and their corresponding enzymatic activities are shown.0. corncobs. NaNO3 and peptone as nitrogen sources and the pH of the nutrient solution adjusted to 6.25 M sulfuric acid hydrolysis at 90 °C for XOS production.6 82. Christov.7 Aachary and Prapulla (2009) Aachary and Prapulla (2009) Aachary and Prapulla (2009) Sabiha-Hanim.. and Rosma (2011) Akpinar et al. (2009a) Akpinar et al.8 10 U/ml 25 U/ml 4. However.7 0. According to these results. 2006).9 U/ml) and cane bagasse (3. Wheat straw Alkali pretreat. Penicillium and Trichoderma showed the highest enzymatic activities on xylan. Trichoderma. Penicillium funiculosum. Fibrobacter. (2013) degraded xylan. it seems more convenient to use weak acids only during the xylan hydrolysis for XOS production and not in the xylan extraction step. janczewskii Penicillium janthinellum P.8 18. U/ml U/ml U/ml U/ml U/ml U/ml U/g . Submerged fermentations using wheat bran. Aspergillus niger.65 0. (2009a) Akpinar et al. (2009a) Akpinar et al. 30 and 60 min (Table 2) were obtained. / Food Research International 51 (2013) 75–85 Table 2 Sources of LCM residues. corn husks.361 U2/1 A. The best substrates for extracting xylan to produce XOS and the best xylanase microorganisms are not yet entirely clear. Bacillus and Thermoascus. (2010) Botella et al. (2005) Sharma. Senani. & Silva. Chytridiomycetes.7 3. wheat straw and sugarcane bagasse were used to isolate 26 species using an agar medium containing xylan. and the genera Aspergillus.7 15. Cotton stalk Alkali pretreat.3 U/ml).8 U/ml) were the best inducers of xylanases. Corncob Alkali pretreat. The combination of several fungal strains. XOS yields of 86.3 20.88 4. janczewskii P.80 A.7 1.88 mg/ml) in 15. Carvalho. 10. modes of action and substrate specificities (Collins.. Kristian.1.. Sharma et al. Some comparative studies of SSF and SmF bioprocess suggested 5–10 times more xylanases in the production by Penicillium brasilianum. & Saini./fer. β-D-xylosidase (β-1. Pinto. 1997). 1997).1.000 U/g substrate in SSF after optimization of the parameters glycerol. 2007).. 8. Chadha.139).55). .2. / Food Research International 51 (2013) 75–85 The grape bagasse was used in solid state fermentation (SSF) by Aspergillus awamori (yield of 40. Some studies showed the highest level of xylanases using the SSF process (Christopher et al. & Olsson. Vršanská. A. the fungus shows good tolerance to low water activity and high osmotic pressure 81 conditions making this process more efficient for bioconversion of solid substrates (Raimbault. Considering the fungi culture in various hemicellulose sources has been shown differences in expression of functionally distinct xylanases (Badhan. Jacqueline. & Saddler. the most studied families are 10 and 11.4-xylan xylohydrolase.2. Sonia.2.1. According to Sharma and Chadha (2011) aeration limitation and the need for mechanical agitation in submerged processes. 2005).37) acts from the non-reducing end of xylobiose or other XOS releasing xylose monomers.. 7. Xylanases: general characteristics and applications. Endo-β-1. such as oligosaccharides from cellulose. 2010). Some microorganisms really stand out in the production of xylanases. In addition. This family consists only of xylanases. & Kluepfel.72).1. Thomson. Tan. Moreover. Members of this family have a molecular weight greater than 30 kDa and a low isoeletric point. & Thonart.4-D xylan xylanohydrolase. EC 3. Hobbs. 1988).1. 2005). Studies have shown that the family 10 xylanases are not totally specific for xylan and can be active on other substrates. a heteropolymer with a complex structure mainly containing xylan. primary amino acid sequences. Tenkanen. after 6 days of incubation at 45 °C (Sharma et al. and Melanocarpus albomyces when cultured under SSF (Jorgensen. 2001. Rodrigues. 2005. Biely. Gerday. and Saini (2005) working with the same specie and sorghum straw as substrate showed 48. 2007). it has been estimated that SSF is 100 times more economical for cellulase production as compared to SmF (Antoine. however. Chadha. 3. niger. α-D-glucuronidases (EC 3. 1995. In contrast. besides better aeration compared with the submerged cultivation (Leite et al. 3) to complete its hydrolysis (Biely. Hemicellulose.. 5.5 times in 72 h showing the importance of substrate in xylanase production (Botella et al. especially batch process with stirred tank reactor are limiting factors in the xylanase production by fungal aerobic process. acetyl xylan esterases (EC 3. There are several types of xylanases and each microorganism can show differences in enzymatic production (Hinz et al. & Goncalves. another culture (Malbranchea flava MTCC 4889) had a high rate of xylanase (15.4-β-xylosidase α-D-glucuronidase 3 β-Xylose α-L-arabinofuranosidase α-araf. considering genetic aspects of biosynthesis and mechanisms of enzyme induction. these enzymes are highly specific for small xylo-oligosaccharides (Biely. when wheat bran was used.. 2010). 2009).1. & Prakasham. requires the catalysis of various enzymes (Fig. Schmidt.73) and p-coumaric esterases (EC 3.4-xylanase (β-1.F. The removal of side groups is catalyzed by α-L-arabinofuranosidases (EC 3.1. 1985).2.4 linkages (Sunna & Antranikian. the enzymes of family 11 show low molecular weights and high isoelectric points (Wong. and they are termed true xylanases. 11 and 43. The production of xylanase with other specie (Aspergillus terreus MTCC 8661) in SSF showed a better performance (115 U/g) in palm oil residue at 35 °C after 60 h incubation (Lakshmi. The interaction between the organism and the source of substrate may be crucial in qualitative and quantitative aspect of enzyme production. The α-4-O-Me-GluUA Acetylxylan Endo-1.. Sahai. Rao. & Feller. ferulic acid esterases (EC 3. Xylo-oligosaccharides 2 2 pcou. Despite the difficulties in the scale up of SSF process when compared with SmF. Pandey et al. Thermomyces lanuginosus ATCC 46882 cultivated in SSF at 45 °C after 4 days of incubation in cellulose bagasse presented 5098 U/g of xylanase (Christopher et al.1. One of the advantages of the SSF process is the low moisture content resulting in lower energy consumption and prevent bacterial contamination. 1985).8) is essential for the depolymerization of xylan. 2010). These enzyme families differ in their physicochemical properties. 2005).000 U/g) with rice straw in SSF process. The main chain consists of xylose residues with β-1. Carvalho et al. Jorgenson. acting on the main chain and releasing oligosaccharides. 2003)..2.A.1. Narang. EC 3. Morkeberg.4 U/g in 24 h). inoculation level and ammonium sulfate concentration. 2005. 2000.73−) (Belancic et al. The definition of the bioprocess is an important factor for xylanase production. Rao.1. Dantas. 2009) according to the structure of different substrates. niger demonstrated better xylanase yield and productivity were obtained with bubble-column and an air-lift bioreactor than in stirred-tank reactor. Studies comparing different types of fermenters with A. In addition to this aspect. & Olsson. Xylanolytic enzymes can be classified as glycoside hydrolases belonging to the families 5.2. In the SSF process the best substrate is one which generates spaces where the growth of hyphae may occur in the presence of oxygen. Thygeson.A. 1998).1.. Schematic structure of hemicellulose and the sites of xylanase reactions. 2007. p-coumaric acid or β-Xylosidase ferulic acid esterase Fig. the production was increased about 2. & Bisaria. wheat straw and corncob) in the culture media for the growth of microorganisms and enzyme production should help to decrease the production costs for the enzyme complexes. to increase XOS production. Furthermore..2 h for maximizing xylobiose yield. with 20 U of xylanase/g xylan at 45 °C (Chapla et al. Akpinar et al. the best production was with xylan from tobacco stalk (XOS yield of 13. suggesting that the immobilized enzyme was more limited to acting on shorter xylans (Lin.8 mg/ml of XOS. XOS yield produced by xylanases from A. such as xylanase type. 1. Catalysis using immobilized and free endo-xylanases from Bacillus halodurans for XOS production from corncob xylan was compared. / Food Research International 51 (2013) 75–85 enzymes of this group are only active on substrates containing D-xylose and long chains of xylo-oligosaccharides. pH 4.. industrial and food wastes (Beg. pH 4.82 A. Under these conditions.. Dupree. XOS was produced by the catalysis of xylan extracted from corncob pretreated by mild alkali conditions (extraction yield of 17.15 mg/ml of xylobiose and 0..59 mg/ml).8%). 2012). Consequently. Akpinar et al. corresponding 10. 87 U/g xylan in 10. 2004). & Sasaki.. with a xylobiose yield of 7. and this demand is a force driving research on xylanases and cellulases. 2009).. producing β-anomers of XOS. Oliva-Neto & Menão. 2010). Fractionation of XOSs with different degrees of polymerization can easily be accomplished by ultrafiltration to remove oligosaccharides with undesirable degrees of polymerization (Akpinar et al..1 mg/ml). and 95% of the total oligosaccharides were xylobiose. Enzymatic technology for XOS production After the pretreatment of the LCM. several processes have been and are being developed to use agro-industrial residues to generate products such as ethanol. after reaction of 8 h. Corncob has high potential to produce endo-xylanases and XOS. 2013).. On the contrary. 1. the bioconversion of these substrates may help reduce the environmental impact caused by the accumulation of waste (Camassola & Dillon. Moreover. The maximum yield of xylobiose (11%) was obtained at pH 5. enzyme dose 15. other aspects influence XOS yield and the composition of oligosaccharides produced by enzymatic reactions. and xylotriose (7%) at pH 5. 2009. due to the production of undesirable products such as furfural and hydroxymethylfurfural and the large amount of monosaccharides released. The conditions of the enzymatic reaction were as follows: 50 °C. the extracted xylan must be treated by enzymatic hydrolysis (Ai et al.95% (1. time and other parameters of the reaction (Table 2). The family 10 xylanases produce XOSs that are smaller than those produced by xylanases from family 11 (Maslen. the immobilized xylanase converted xylan to XOS with shorter lengths and 25.7%).9%) using a partially purified xylanase from Aspergillus foetidus MTCC 4898.1 h (Jayapal et al. 2011).. The enzymatic hydrolysis produced 60% (6. equivalent to 3. 2010). niger was greater than xylanases from Trichoderma longibrachiatum on extracted xylan. The incorporation of cheap sources (such as sugarcane bagasse. Oliva-Neto.1%.4 and 50 °C for 14 h. USA) for hydrolysis of xylan from grass extracted by alkaline hydrolysis produced approximately 2. produced in situ via microbial fermentation or immobilized inside the biomass (Dorta. xylan composition. Brienzo et al. 2009). . while for maximum xylotriose yield. mainly xylobiose and xylotriose.. A response surface analysis predicted the ideal conditions to be41 °C. Goubet. and xylobiose (70.b. Moure et al.5 h. suggesting that free xylanase worked on both longer (insoluble) and shorter (soluble) xylan chains. xylobiose (1.95 mg/ml.9. 2001. Watanabe. Subramanian & Prema. efficiently exposed the xylan to the action of endo-xylanases.0. acid hydrolysis is not recommended for this step. viridae (Sigma..9% xylobiose.1 h. However. the demand for enzymes is growing faster than ever. niger at 50 °C over 24 h. In the enzymatic process of oligosaccharide production. & Lee. 2011) or an acid treatment (Akpinar et al.4 bonds in the main chain of xylan. According to Song and Wei (2010).. In addition. 2007).. was obtained. The enzymatic complex must have a low activity of exoxylanases (β-xylosidases) to attenuate the production of xylose. dose 29.. Kapoor. However. the production costs and low yields are important problems for industrial applications.6 U/g and reaction time 19. to improve flour for bakery food products. 2006.A. The same work compared the xylanases from different microorganisms.. Jayapal. (2004). Adam.4 U/g and an incubation time of 18. xylotriose and xylotetraose (Yang et al.7 mg/ml) xylooligosaccharides..4 xylan bonds. Tseng. 2010). 2010.5%) was the major component of the XOS mixture produced (Aachary & Prapulla. Moreover.0 at 45 °C.1 mg/ml. et al.3. the type of pretreatment. Carvalho et al.0 at 40 °C and 66 U/g xylan in 16. after 96 h with 2. 2012a. The free enzyme was more efficient in XOS production than the immobilized one. 1997). 2009a. 2005. Experimental studies using 233 U/g endo-xylanase from Aspergillus oryzae MTCC 5154 and alkali-pretreated corncob (6%) at pH 5. the enzyme can be added directly to the reaction medium (Akpinar et al. a high yield of XOS (79.6% xylose (Sabiha-Hanim et al. Moreover. Techapun. 2010). According to Sun et al. 1.63% xylotetraose and 25.F.97% xylotriose. the conditions were 40 °C. 2009).57 mg/ml of xylotriose were obtained.. 2002).. USA) was observed at 40 °C.. 2011). 2009). 2008).18 mg/ml) and yields of other XOSs in lesser amounts (Akpinar et al. 2010. proteins and enzymes using microorganisms (Lakshmi et al. an endo-xylanase. 2009. pH 4. 2005.7 mg/ml) and xylotriose (1.6% substrate.. Production of XOS is carried out by xylanases hydrolyzing β-1. Xylanolytic enzymes are highlighted due to their potential applications in the bioconversion of lignocellulose to sugars (Lakshmi et al. with T. The free enzyme converted xylan to higher-level oligomers with a degree of polymerization greater than 4. The pretreated xylan from triploid Populas tomentosa was converted into XOS by a crude xylanase from Pichia stipitis.13. 2009). Under these conditions. Mahajan.. Santos et al. and enzymes that remove side groups must be used (Aachary & Prapulla.. Currently. immobilized (Jiang et al. The hydrolysis of different xylans was compared for XOS production using 200 U/g of xylanase from A. This enzyme converted 36. the enzymatic hydrolysis with the xylan extracted from sugar cane bagasse pretreated with alkali and peroxide showed a maximum XOS conversion of 37.8% of the xylan to XOS. Poosaran.. 2012). The use of the endoxylanase from Trichoderma viridae (Sigma. which inhibits XOS production (Vázquez et al. The sugar yield was: 13. 2009a). 5. pH 8. They also have potential applications in industries in the clarification of juices and vegetable oil extracts. The maximum XOS production using xylan from sugar cane bagasse extracted by alkali and reacted with a commercial endoxylanase from T. Under these conditions. Yang et al. & Moura. which hydrolyses β-1.. xylanases can be used to produce high-value xylo-oligosaccharides (Vázquez et al.3 U/g in 8 h. 2011). the agroindustrial residue of palm oil was pretreated by autohydrolysis and the solid residue obtained was hydrolyzed using xylanases from Trichoderma viride. 2000).8 U/g xylan and 2% of substrate in 24 h. Rodrigues et al. longibrachiatum producing large amounts of monosaccharides. they have low catalytic versatility and the products of their action can be hydrolyzed by the enzymes of family 10 (Biely et al.. a xylotriose yield of 5. 12. Polizeli et al. 2006. & Stephens.2% of the mixture composed by xylobiose and xylotriose. 2002. Cruz.5% xylobiose and xylotriose. as bleaching agents in pulp and paper and in the saccharification of agricultural. as well as 32. & Hoondal. enzymatic hydrolysis is considered the best option to produce XOS for the food industry (Aachary & Prapulla. as aids in the digestive acquisition of nutrients by pigs and birds that use cereal-based diets.0 with a dose of 13. 2003). (Samanta.9% (1. Carvalho et al. .. M. Tamashiro... S. S.. D. Penicillium purpurogenum produces several xylanases: Purification and properties of two of the enzymes. Szakacs. (2007). M. 119–125. M. The maximum concentration of XOS obtained in the experiments was 5. 83 Ai. H. L. 1003–1009. Blaut.. Peirano.. Selected indigestible oligosaccharides affect large bowel mass and fecal short-chain fatty acids. B.7 mg/ml (Brienzo et al. FEMS Microbiology Reviews. (2011).. Bissoon.0. P. R.. National company of supply. Food Research International. & Balakrishnan.. A...7–5. Collins. H.. Carvalho. 41. Cellulase-free xylanase production from an alkalophilic Bacillus species. & Pastore. López. A. XOS production research is as important as studies of applying XOS to replace antibiotics in feed and to prevent important diseases in animals and humans. the using lignocellulosic residues for XOS production represent an addition to the economic value of these products and an increase in food production without the increase of agricultural areas because XOS can be produced from agroindustrial residues. 46. Balakrishnan.. Szendefy. C. M. & Saini. A.. Antoine. J.. Chadha.. W. P. Steiner. Enzymatic production of xylooligosaccharide from selected agricultural wastes. & Szakacs. & Li. Biochemical Engineering Journal. Akpinar. & Blandino. 41. 756–761. World Journal of Microbiology and Biotechnology. and mixtures of these XOS at 1. & Shah. Conclusion The production of XOS. b) corncob is the one of the best substrates for XOS production. A. Y.. F. but other substrates can be used. Xylo-oligosaccharides production from alkali-pretreated sugarcane bagasse Using xylanases from Thermoascus aurantiacus. Abdel-Sater. & Thonart. 2011)... M. & Hoondal. Badhan. The Journal of Nutrition. A. G. The enzymatic reaction yielded 40% of XOS (xylobiose and xylotriose) after 48 h of reaction (Carvalho et al.F. 8. 130–136. & Pastore.. J. Chapla et al. Microbial xylanases and their industrial applications: A review. D. M. 34. J. and pH value in the elderly. J. (2006). Biochemical Engineering Journal. (2009). Ko. S. A. Value addition to corncob: Production and characterization of xylo-oligosaccharides from alkali pretreated lignin-saccharide complex using Aspergillus oryzae MTCC 5154. such as sugar cane bagasse. / Food Research International 51 (2013) 75–85 60 U/g of crude enzymatic extract from Thermoascus aurantiacus at 50 °C and pH 5. 991–995. 115. CONAB (2012). P. I. P. Optimization of Paulownia fortunei autohydrolysis–organosolv pulping as a source of xylooligomers and cellulose pulp. 973–981. Campbell. G... Emergence of a debate. aiming to improve the yield and quality of XOS and its use as a functional ingredient in human and animal nutrition. & Chan... Gerday.... T. I. Industrial and Engineering Chemistry Research. D.. (2009).. S.. M. K. F..4-xylanase families: differences in catalytic proprieties. 660–666. Jacqueline. & Kluepfel.. Journal of Biotechnology. 47. and their mode of action. A.. & Bostanci. including alkaline and acid hydrolysis pretreatments and XOS production by acid or enzymatic hydrolysis. H. 11–16. D. H. Ory. Carvalho. Oliva-Neto. AGPs and public health. Christopher. (2001).. Current research must focus on developing viable and economic technologies from lignocellulosic residues reducing production cost and increasing the availability of XOS to develop a wider market for XOS consumption.0.A. (2007).gov. 215–221. & Wolf.. A. can contribute to the food and feed industries because it is an important functional food ingredient with benefits for human and animal health. Lin et al. & Milagres. C. 326–338. Journal of Industrial Microbiology and Biotechnology. In addition. G. Production. 3167–3173. 3230–3235. 2010. L. F.. Christov. depending on the microorganism. Biely. V. Production of xylooligosaccharides from corncob xylan by fungal xylanase and their utilization by probiotics. 2012a. (2005)... C. Xylan-decomposing fungi and xylanolytic activity in agricultural and industrial wastes. xylanases. 24. Nutrition Research. Pandit. Microbial xylanolytic systems. Other option is the rapid thermo-acid hydrolysis of LCM. Foz do Iguaçu. Q. 145–151.. H. 57. (1995).. As exposed in this review. L.. 29. Brazil. J. & Rele. C.. (2002). more studies of microorganisms and the production and application of xylanases to improve XOS yields are necessary. Xylan structure. W. http://www. 33. 29. 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