Gustavo Graciano Fonseca

Evaluation of frankfurters obtained from croaker (Micropogonias furnieri) surimi and mechanically deboned chicken meat surimi-like material

In order to develop a healthy low-fat frankfurter-type sausage, different levels of surimi-like material prepared from mechanically deboned chicken meat (MDCM) and whitemouth croaker (Micropogonias furnieri) meat surimi were employed in five different recipes in the percentage ratios of 100/0, 70/30, 50–50, 30/70, and 0/100, respectively. The functionality of both fish and chicken protein concentrates was evaluated based on texture analysis (breaking force, deformation, gel strength and shear force). Growth kinetics for aerobic bacteria were analyzed using the modified Gombertz model. Shelf-life was determined based on microbiological counts and sensory analysis on acceptance tests. Surimi source reflected in the physical properties of the frankfurters. Addition of MDCM surimi-like material to sausage favored greater shear force, breaking force, and gel strength. On the contrary, the increasing levels of croaker surimi reduced rheological parameter values. Deformation presented no evident correlation between the formulations and with other textural properties. Average of textural properties obtained during storage where 2.29 ± 0.16 N for breaking force, 0.74 ± 0.02 cm for deformation, 1.69 ± 0.14 N cm for gel strength, and 14.2 ± 0.8 N for shear force, for frankfurters prepared with MDCM surimi-like material. Frankfurters presented an average shelf-live of 42 days at 4°C. Mathematical models had good correlation, and may be utilized for predictive applications.

Bioprospecting of yeasts for amylase production in solid state fermentation and evaluation of the catalytic properties of enzymatic extracts

Profiling microorganisms with potential for amylase production in low cost culture media has been widely recognized due to its broad applicability. The aim of this study was to select yeast strains with potential to produce amylolytic enzymes by solid state fermentation. Fifty-four (54) strains were assessed and three exhibited ability to produce amylases: Candida parapsilosis with 14.68 U/mL (146.8 U/g substrate); Rhodotorula mucilaginosa with 25.0 U/mL (250 U/g substrate), and Candida glabrata with 25.39 U/mL (253.9 U/g substrate), in solid state fermentation, for 120 h at 28°C, using wheat bran with 70% moisture. The enzymes exhibited maximum activity at a pH of 7.0 and at 60°C. Amylases demonstrated satisfactory structural stability, maintaining their catalytic activity after 1 h at 50°C. All enzymes were ethanol tolerant and retained more than 70% of their original activities in 15% ethanol solution. Corn starch was efficiently hydrolyzed by enzymes and the extracts produced by C. parapsilosis and C. glabrata exhibited dextrinizing activity, while those produced by R. mucilaginosa exhibited saccharifying activity. Key words : Candida parapsilosis, Candida glabrata, Rhodotorula mucilaginosa , dextrinizing and saccharifying activity

Production and characterization of β-glucosidase from Gongronella butleri by solid-state fermentation

Among the enzymes of the cellulolytic complex, β-glucosidases are noteworthy due to the possibility of their application in different industrial processes, such as production of biofuels, winemaking, and development of functional foods. This study aimed to evaluate the production and characterization of β-glucosidase from the filamentous fungus Gongronella butleri, recently isolated from Cerrado soil and cultivated in agro-industrial residue substrates. The highest production of β-glucosidase, about 215.4 U/g of dry substrate (or 21.5 U/mL), was obtained by cultivation of the microorganism on wheat bran with 55% of the initial moisture, for 96 h at 30°C. This β-glucosidase showed higher catalytic activity at pH 4.5, and a temperature of 65°C. The original enzymatic activity was recovered in a pH range of 3.0-7.5 after 24 h of incubation. The enzyme retained 80% of its catalytic activity when incubated for 1 h at 50°C. The enzyme was strongly inhibited by glucose, an effect that was completely reversed by increasing substrate concentration in the reaction mixture, which is typical for competitive inhibition. High catalytic activity was observed in solutions containing up to 20% ethanol, allowing the application of this enzyme in processes with high alcohol concentrations (for example beverages and biofuels). The significant production of β-glucosidase by the selected strain, along with these enzyme characteristics, highlights the biotechnological potential of the fungus G. butleri. Key words: Microbial enzyme, biofuels, agro-industrial residues, cellulases, hemicellulases.

Production and Catalytic Properties of Amylases from Lichtheimia ramosa and Thermoascus aurantiacus by Solid-State Fermentation

The present study compared the production and the catalytic properties of amylolytic enzymes obtained from the fungi Lichtheimia ramosa (mesophilic) and Thermoascus aurantiacus (thermophilic). The highest amylase production in both fungi was observed in wheat bran supplemented with nutrient solution (pH 4.0) after 96 hours of cultivation, reaching 417.2 U/g of dry substrate (or 41.72 U/mL) and 144.5 U/g of dry substrate (or 14.45 U/mL) for L. ramosa and T. aurantiacus, respectively. The enzymes showed higher catalytic activity at pH 6.0 at 60°C. The amylases produced by L. ramosa and T. aurantiacus were stable between pH 3.5–10.5 and pH 4.5–9.5, respectively. The amylase of L. ramosa was stable at 55°C after 1 hour of incubation, whereas that of T. aurantiacus maintained 60% of its original activity under the same conditions. Both enzymes were active in the presence of ethanol. The enzymes hydrolyzed starch from different sources, with the best results obtained with corn starch. The enzymatic complex produced by L. ramosa showed dextrinizing and saccharifying potential. The enzymatic extract produced by the fungus T. aurantiacus presented only saccharifying potential, releasing glucose monomers as the main hydrolysis product.

Yield, viscosity, and gel strength of wami tilapia (Oreochromis urolepis hornorum) skin gelatin: Optimization of the extraction process

A factorial design and response surface methodology were used to optimize the extraction process of tilapia skin gelatin (Oreochromis urolepis hornorum). The concentrations of NaOH (0.15%–0.35%) and H2SO4 (0.15%–0.35%), the extraction temperature (40°C–60°C), and the extraction time (3–15 h) were independent variables. Response variables were yield (%), viscosity (mPa·s), and gel strength (g). The NaOH (%) and H2SO4 (%) concentrations had significant influences (p<0.05) on viscosity and gel strength, while the extraction temperature (°C) and the extraction time (h) showed significant influences (p<0.05) on all dependent variables. Increasing the temperature and extraction time provided higher yields with a reduction in the gelatin viscosity and gel strength. Tilapia fish skin can be used as a source for production of gelatin.

Physical and chemical properties of wami tilapia skin gelatin

Gelatin was extracted from the skin of tilapia (Oreochromis urolepis hornorum) and characterized according to its physical and chemical properties. It had pH 4.66, which is slightly higher than the values reported for gelatins processed by acid solubilization. In general, the ionic content was low, and the average yield of the process was 5.10 g/100 g. The proximal composition of the gelatin was similar to that of the commercial gelatins, with slightly higher moisture content. The tilapia skin gelatin had whitish-yellow color and average turbidity of 67 NTU.

Low-fat frankfurters from protein concentrates of tilapia viscera and mechanically separated tilapia meat

In order to develop a healthy low-fat frankfurter-type sausage, different formulations were developed with tilapia viscera surimi (T1) and two with mechanically separated tilapia meat (MSTM) surimi (T2 and T3), all without pig lard addition. Due to technological problems observed for T1 sausage during cooking, it was not further investigated. The functionality of the other two formulations was evaluated based on proximate composition, pH, water activity, and texture. Finally, microbiological and sensory analyses based on acceptance tests were performed. Listeria monocytogenes and Salmonella spp. were found to be absent. T2 showed higher frequencies for the attributes color (90.0%) and overall acceptability (86.7%), while T3 showed higher frequencies for taste (86.7%) and texture (96.7%). The surimi concentration was reflected in the physical properties of the sausages. It was found that the addition of MSTM surimi to sausage favored greater cutting strength (3.9 N for T2 and 4.9 N for T3). Beyond the surimi utilization, the total replacement of pig lard by cassava starch and soybean protein had also contributed with the texture properties.

Influence of treatments in the quality of Nile tilapia (Oreochromis niloticus) fillets

Abstract In this study, the influence of different treatments was evaluated: nonwashing, washing in chlorinated water and washing/soaking in chlorinated water and sodium chloride on the quality of Nile tilapia (Oreochromis niloticus) fillets during storage at 1.0 ± 0.5°C through daily analysis of pH, moisture, and lipids content. Microbiological analysis and growth modeling for mesophilic and psychrotrophic bacteria and Staphylococcus sp. were also carried out. Finally, we confirmed the microbiological safety through sensory analyses. The main results suggest that fillets washed or soaked in chlorinated water and sodium chloride present clear and narrower blood line coloration; that is, they are less oxidized than those that received other treatments and are microbiologically safe for use within 12 days of storage. It was concluded that the treatments in chlorinated and salinized water favored the quality maintenance of fillets.

Characterization of wami tilapia (Oreochromis urolepis hornorum) skin gelatin: microbiological, rheological and structural properties:

Gelatin was extracted from the skin of tilapia (Oreochromis urolepis hornorum) and its microbiological, rheological and structural properties were characterized. The tilapia skin gelatin presented typical molecular weight distribution of type I collagen with contents of imino acids (proline + hydroxyproline) of 21.67%. Gel strength and viscosity values were 221 ± 5.68 g and 5.98 ± 0.34 cP, respectively, with the maturation time of 18 ± 1 h, and both parameters increased with the maturation time. Melting and gelling points of 25 ℃ and 21 ℃, respectively, were obtained for tilapia skin gelatin. The gelatin presented microbiological standards in accordance with the Brazilian Legislation.

Production, characterization, and evaluation of the stability of biodiesel obtained from greasy agroindustrial waste during storage.

ABSTRACT Greasy agroindustrial waste from the process of cooking hog meat was used to produce biodiesel (fatty acid methyl esters and fatty acid ethyl esters) under a specific storage condition. The operating conditions necessary to achieve the optimal relationship between quality and productivity were assessed. Next, batches of methyl and ethyl biodiesels were produced, generating 2 L of each product to evaluate their stability during 150 days of storage. The following study indicates that, for methyl route, the molar ratio (1:5) and catalyst (0.5%) yielded the best result of 90.77% (w/v) and quality parameters within the international standards. The ethyl route also showed the highest yield (77.09% w/v) and better quality parameters with a molar ratio (1:5) and catalyst (0.5%). No significant differences were observed in the methyl biodiesel obtained from the batch process for up to 45 days, while the ethyl biodiesel degraded in 30 days of storage.