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La enzima Transglutaminasa microbiana (MTGasa) es ampliamente usada en la industria alimentaria como aditivo para mejorar las propiedades mecánicas y de textura de los alimentos. El proceso de producción de la enzima es caro debido al valor de los componentes del medio de fermentación utilizados, por ello se evaluó la posibilidad de utilizar materias primas baratas, como fuente de nutrientes para el crecimiento de Streptomyces mobaraensis. El estudio económico de la producción de MTGasa con una variedad de materias primas sería un proceso largo. El software de simulación de procesos industriales SuperPro Designer® v7.5 fue utilizado, basándose en datos obtenidos de fermentaciones a escala de banco, para estimar el consumo de servicios, costos de capital, costos de operación e ingreso por el producto. El modelo mostró el estimado de los costos de producción de MTGasa utilizando glucosa obtenida de la hidrólisis enzimática de granos de sorgo y suplementada con granos secos destilados con solubles (DDGS por sus siglas en inglés, Dried Distillers Grains with Solubles). En la planta productora de MTGasa, utilizando hidrolizados enzimáticos, se obtuvo una ganancia bruta anual de 12,326 x 106 US$ y un tiempo de recuperación de la inversión de 4.01 años.

Sorghum straw can be hydrolysed to obtain monosaccharide solutions, mainly containing xylose. The usual biotechnological application of xylose is its bioconversion to xylitol. The global process from straw to xylitol can give an added value to the sorghum straw. The process has the following sequential steps: reduction of size, acid hydrolysis, neutralization, detoxification, fermentation, recovery and purification. This work deals with the optimization of the detoxification process of sorghum straw hydrolysates with activated charcoal. The variables evaluated were pH (1–5), contact time (20–60 min) and activated charcoal charge (20–33 g kg−1). Mathematical models were obtained through a factorial experimental design. The models suggest that optimal conditions for detoxification are pH 1, contact time of 29 min and a charcoal charge of 33 g kg−1. These conditions allowed hydrolysates with 54.2 g xylose L−1, 13.5 g glucose L−1, 12 g arabinose L−1, 0.2 g furfural L−1 and 0.0 g acetic acid L−1 to be obtained. The results suggest that performing the detoxification step before the neutralization step gave the best outcome. Fermentations by Candida parapsilosis NRRL Y-2315 were performed and it was confirmed that the treated hydrolysate is suitable for xylitol production, yielding up to 17 g L−1 of this polyol. Copyright © 2006 Society of Chemical Industry

Restructured fish products from the filleting waste from silver carp (Hypophthalmichthys molitrix) were obtained using sodium caseinate (1%), whey protein concentrate (WPC) (1%) or MTGase (0.3%) at different levels of salt (0%, 1% or 2%). The restructured products were obtained by incubating at 40 °C for 60 min and then at 90 °C for 20 min. Changes in the mechanical properties were studied by measuring changes in the textural profile analyses, punch test and torsional test analyses and expressible water. The mechanical properties increased when the salt level was also increased. The mechanical properties of non-salted and low-salt products were increased by using dairy proteins. Sodium caseinate had a greater effect in improving mechanical properties than WPC. MTGase increased expressible water. The results obtained showed that the mechanical properties of low-salt restructured fish products can be improved by using dairy proteins combined with MTGase, with a slight increase in expressible water.

Sorghum straw is a raw material useful for the xylose production by hydrolysis. The main application of xylose is its bioconversion to xylitol, a functional sweetener with important technological properties. The objective of this work was to study the hydrolysis of sorghum straw with hydrochloric acid at 100 °C. Several concentrations of HCl (2–6%) and reaction time (0–300 min) were evaluated. Kinetic parameters of mathematical models for predicting the concentration of xylose, glucose, acetic acid and furfural in the hydrolysates were found and used to optimise the process and compared with results reported in the literature using other conditions and acids. Optimal conditions found for hydrolysis were 6% HCl at 100 °C for 83 min, which yielded a solution with 21.3 g xylose/l, 4.7 g glucose/l, 0.8 g furfural/l and 2.8 g acetic acid/l.

Lactic acid bacteria are generally recognized as nutritionally fastidious. The complexity of the media increases the cost of lactic acid production. In this study a low-cost nutrient medium based on corn steep liquor (CSL) was developed for lactic acid production by Lactobacillus delbrueckii NRRL B-445. Starting from a medium containing 90 g l -1 glucose and 20 g Pl -1 CSL as a sole nutrient source, 70.7 g l -1 lactic acid was obtained with an economic efficiency of 98 g lactic acid per € nutrient. Other media, made with CSL and each individual component (yeast extract, peptone, sodium acetate, sodium citrate, K 2 HP0 4 , MgSO 4 -7H 2 O, MnS0 4 -H 2 0 or FeSO 4 -7H 2 O) of a general (Merrier) lactobacilli medium were also assayed. The highest economical efficiency (134g lactic acid per € nutrient) was obtained supplementing 10 gl -1 CSL with 0.05 gl -1 FeSO 4 -7H 2 O. Additionally, lactic acid production and glucose consumption were mathematically modelled and the regression parameters obtained were correlated with CSL concentration by linear or exponential equations.

Low-salt restructured silver carp products were obtained using mechanically deboned fish meat from filleting wastes of silver carp (Hypophthalmichthys molitrix). The additives used were NaCl at three levels (0 (control), 10 and 20 g kg−1) and microbial transglutaminase (MTGase) also at three levels (0 (control), 3 and 6 g kg−1). The fish meat was massaged with the additives at

Xylose is a hemicellulosic sugar that can be used as a carbon and energy source for the growth of microorganisms. The main use of xylose is its bioconversion to xylitol. Sorghum straw is a raw material for xylose production that has not yet been studied. The objective of this work was to study xylose production by hydrolysis of sorghum straw at 122°C, using three concentrations of sulphuric acid (2%, 4% and 6%). Kinetic parameters of mathematical models for predicting the concentration of xylose, glucose, acetic acid and furfural were found and optimal conditions selected. These were 2% H2SO4 at 122°C for 71 min, which yielded a solution with 18.17 g xylose/l, 6.73 g glucose/l, 0.9 g furfural/l and 1.51 g acetic acid/l.

Sorghum straw is a renewable, cheap and widespread resource. The acid hydrolysis of sorghum straw to obtain xylose solutions could be a good alternative for this abundant resource. The H 2 SO 4 hydrolysis of sorghum straw at two different temperatures (80 and 100°C) and three H 2 SO 4 concentrations (2, 4 and 6%) using a solid/liquid ratio of 1:10 (wlw) was studied. Kinetic parameters of mathematical models for predicting the concentrations of xylose, glucose, acetic acid and furfural were determined. The activation energy of the release reaction was 183.3 kJ mol -1 for xylose and 185.8kJ mol -1 for glucose. The optimal conditions found were 6% H 2 SO 4 at 100 °C for 60min, which allow one to obtain a solution with 18.27 g xylose l -1 , 6.78 g glucose l -1 , 0.7 g furfural l -1 and 1.35 g acetic acid l -1 . It is concluded that this process has potential for utilisation of this renewable lignocellulosic resource. La paille de sorgho est une ressource renouvelable, pas chere et repandue et pourrait etre traitee par hydrolyse acide pour obtenir des solutions de xylose. L'objectif de cette etude est d'evaluer l'hydrolyse par H 2 SO 4 de paille de sorgho a pression atmospherique. Les parametres cinetiques de 2 modeles mathematiques pour predire les concentrations de xylose, glucose, acide acetique et furfural sont determines. Les resultats montrent le potentiel de ce procede pour l'utilisation de cette ressource lignocellulosique.

Sorghum straw is a waste that has been studied scarcely. The main application is its use as raw material for xylose production. Xylose is a hemicellulosic sugar mainly used for its bioconversion toward xylitol. An alternative use could be its conversion toward furfural. The objective of this work was to study the furfural production by hydrolysis of sorghum straw with phosphoric acid at 134 degrees C. Several concentrations of H(3)PO(4) in the range 2-6% and reaction time (range 0-300 min) were evaluated. Kinetic parameters of mathematical models for predicting the concentration of xylose, glucose, arabinose, acetic acid and furfural in the hydrolysates were found. Optimal conditions for furfural production by acid hydrolysis were 6% H(3)PO(4) at 134 degrees C for 300 min, which yielded a solution with 13.7 g furfural/L, 4.0 g xylose/L, 2.9 g glucose/L, 1.1g arabinose/L and 1.2g acetic acid/L. The furfural yield of the process was 0.1336 g furfural/g initial dry matter was obtained. The results confirmed that sorghum straw can be used for furfural production when it is hydrolyzed using phosphoric acid.

The efficiency of microbial transglutaminase (MTG), obtained by Streptoverticillum ladakanaum in the fermentation of sorghum straw hydrolysates to increase mechanical properties of restructured fish products, was evaluated. Fish gels were obtained from Mexican flounder (Cyclopsetta chittendenni) by (1) adding MTG obtained in the fermentation of sorghum straw hydrolysates (SMTG) at 0.3 units/g; (2) adding commercial MTG (CMTG) at 0.3 units/g; (3) adding 0.4% calcium chloride to activate the endogenous TG; and (4) without additives as control sample. SMTG more efficiently increased the mechanical properties of restructured products and induced a low value of expressible water, similar to the control (6% to 7%). Results demonstrated the feasibility of producing an efficient MTG from agricultural wastes. Keywords: fish, transglutaminase, microbial, restructured, sorghum