Abstract

MARTINEZ-CORONA, R. et al. Effect of initial substrate concentration and agitation on xylitol production by fermentation of hydrolyzed tamarind seed media with Kluyveromyces marxianus. Rev. Mex. Ing. Quím [online]. 2015, vol.14, n.2, pp.393-403. ISSN 1665-2738.

Tamarind seed consists of 50 to 72 % of a branched heteropolysaccharide, called xyloglucan. By fragmenting xyloglucan with a coupled process of acid hydrolysis and thermal treatment, it is possible to obtain considerable amounts of fermentable sugars, glucose and xylose being the most abundant Xylose is the precursor of xylitol, a sugar with similar characteristics to sucrose. Chemical synthesis of xylitol is very expensive and of low-yield. On the other hand, xylitol can be obtained by fermentation, using yeasts that incorporate xylose in their metabolism, such as Kluyveromyces marxianus. Being a biological process, xylitol production by fermentation depends on different environmental factors. In this paper, the effect of two factors on xylitol production was evaluated based on a 3² factorial experimental design: initial substrate concentration (20-80 g/L) and agitation (120-240 rpm). Both factors considerably influenced xylitol production of K. marxianus, where the optimization of the experimental design predicted a yield of 0.57 g of xylitol/g of xylose, with an initial substrate concentration of 50 g/L and an agitation of 177 rpm, from a source substrate of which there are no reports of its use in this field, such as tamarind seed.

Keywords : xylose; fermentation; xylitol; initial substrate concentration; agitation.

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