Purification of Xylitol Obtained by Fermentation of Corncob Hydrolysates

Abstract

Hydrolysates obtained by autohydrolysis-posthydrolysis of corncobs were detoxified with charcoal, concentrated, supplemented with nutrients, and fermented with Debaryomyces hansenii. After biomass removal, the fermented media contained 0.1137 kg of nonvolatile components (NVC)/kg of liquor, which corresponded mainly to xylitol (0.6249 kg/kg of NVC) but also to minor amounts of inorganic components (measured as ashes), proteins, nonfermented sugars (xylose and arabinose), uronic acids, arabitol, and other nonvolatile components (ONVC). The media were subjected to further processing (sequential stages of adsorption, concentration, ethanol precipitation, concentration, and crystallization) to obtain food-grade xylitol. Adsorption experiments were carried out at various solid-to-liquor ratios. Under selected conditions (1 kg of charcoal/15 kg of liquors), the xylitol content increased to 0.6873 kg/kg of NVC, and almost total decoloration was achieved. The resulting liquor was concentrated by evaporation to increase its NVC content to 0.4032 kg/kg of liquor (corresponding to a xylitol concentration of 0.280 kg/kg of liquor), and ethanol was added to precipitate a part of the NVC (mainly proteins, but also uronic acids, ashes, and other nonvolatile compounds). Refined liquors (containing 0.7303 kg of xylitol/kg of NVC) were concentrated again, and ethanol was added (to reach 40-60% volume of the stream) to allow crystallization at -10 or -5 degrees C. Under selected conditions, 43.7% of xylitol contained in the initial fermentation broth was recovered in well-formed, homogeneous crystals, in which xylitol accounted for 98.9% of the total oven-dry weight. Material balances are presented for the whole processing scheme considered in this work.

Simultaneous lactic acid and xylitol production from vine trimming wastes

“…11,12 The worldwide production is abut 30 000 tons per year. 13 With a sweetening power similar to sucrose, xylitol shows additional technological and biological properties fostering its utilization in the food industry as a food ingredient, including: (i) anticariogenic properties; (ii) suitability for diabetics; (iii) negative heat of solution (about -34.8 cal g −1 , causing a 'freshness' feeling when coming into contact with the saliva); (iv) it does not undergo the Maillard reaction, responsible for both darkening and reduction in the nutritional value of proteins; (v) when continuously supplied in diet, it limits the tendency to obesity; and (vi) incorporation of xylitol in food formulations improves the color and taste of preparations without causing undesired changes in properties during storage.…”

Synthesis and Characterisation of Polyethersulfone Membranes Incorporated with Titanium Dioxide Nanoparticles for Xylitol Separation from Mixed Sugars Solution

“…3 Xylitol could also be commercially obtained chemically by using catalyst, 4 or biotechnologically by using fungi, bacteria or yeast. 5 The separation performance of xylitol is a complicated process due to presence of impurities and this separation can be achieved by using different techniques such as: (1) crystallisation (75%), 6 (2) adsorption (60%), 7 or (3) membrane technology (82%). 8,9 Based on this, membrane technique is reported to have given the highest purity compared to others.…”

Evaluation of wine vinasses as alternative nutrients in biotechnological processes Evaluación de vinazas vínicas como nutriente alternativo en procesos biotecnológicos

“…The global demand is expected to be around 200,000 tons/year by the end of 2011 (Reddy, Altaf, Naveena, Venkateshwar, & Kumar, 2008). Meanwhile, xylitol, a five-carbon polyol with increasing interest owing to its dietetic and clinical properties, has a comparatively high added value and growing market, the world-wide production being estimated about 30,000 tons/year (Rivas, Torre, Dominguez, Converti, & Parajo´, 2006a). Owing to its negative dissolution heat, xylitol produces a feeling of vaporisation in the oral and nasal cavities, when used as a part of the coating of confectionery or pharmaceutical products such as vitamins or expectorants, and in the formulation of dietary complements (such as amino acids, vitamins, trace elements and non-reducing sugars) (Parajo´, Domı´nguez, & Domı´nguez, 1998).…”