Alexandre da Trindade Alfaro

Fish Gelatin: Characteristics, Functional Properties, Applications and Future Potentials

Gelatin, an important biopolymer derived from collagen, is widely used by various industries because of its functional and technological properties. The vast majority of commercial gelatin is derived from mammals, but due to many sociocultural and religious reasons, there is an increasing demand for alternative sources. The by-products generated by the fish-processing industry are a potential source for the production of gelatin. The high potential of fish gelatin production is due to the large quantities of collagen by-products generated. However, the main restriction to its use regards their lower rheological properties when compared to mammalian gelatin, which limits its range of applications. This review discusses the latest scientific literature about the main characteristics and functional properties of fish gelatin, which shows the main strategies used to improve its properties, as well as its applications and future potentials.

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.

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.

Avaliação reológica e físico-química da gelificação térmica do surimi de jundiá

The objective of this work was to evaluate the rheological and physicochemical properties of thermal gelling of surimi from silver catfish (Rhamdia quelen). Four heating treatments were used: one-step heating at 90oC, for 15 min, was compared with three two-step treatments with pre-heating at 60oC for 30, 45 and 60 min, followed by heating at 90oC for 15 min. Each heat treatment was used on three formulations: two with protease inhibitors (bovine serum albumin + alpha2-macroglobulin and egg white) and a formulation without inhibitors. Samples with inhibitors and one-step heating reached better gelling, by an increase in the storage modulus and a decrease in phase angle. Pre-heated gels had large variation in viscoelastic parameters which interfered with the establishment of the protein network during thermal gelling of surimi. The soluble peptides concentrations did not change significantly, even when two-step heating was carried out, which indicates absence of proteolysis, besides showing protein network protection by inhibitors.

Application and evaluation of propolis, the natural antioxidant in Italian-type salami

O presente estudo teve por finalidade caracterizar a propolis quanto a sua atividade antioxidante e aplica-la na elaboracao de salame tipo italiano. Amostra de propolis foi coletada e submetida a caracterizacao fisico-quimica, quimica e capacidade antioxidante. Quatro formulacoes de salame foram elaboradas: F1 (sem antioxidante), F2 (adicao BHT 0,01%), F3 (adicao de propolis 0,01%) e F4 (adicao de propolis 0,05%). Os salames foram avaliados quanto as propriedades fisico-quimicas e oxidacao lipidica. A caracterizacao da propolis mostrou alto teor de ceras e baixo teor de compostos fenolicos e flavonoides, porem em quantidades suficientes para comprovar sua atividade antioxidante. Os salames tipo italiano apresentaram teor de umidade, proteinas e lipideos conforme limites preconizados pela legislacao brasileira. A formulacao F4 (0,05% de propolis) apresentou melhor resultado quando comparado as formulacoes F3 (0,01% de propolis) e F1 (sem antioxidante). No entanto, a F2 (0,01% de BHT) foi a formulacao que apresentou menor valor de oxidacao lipidica. Os resultados demonstraram que a propolis inibe a acao oxidativa, podendo ser adicionada em produtos carneos como antioxidante natural.

PRODUÇÃO DE GELATINA DE PELE E OSSOS DE BAGRE (Clarias gariepinus)

O presente estudo teve como objetivo produzir gelatinas de pele e ossos de bagre (Clarias gariepinus) e determinar a viscosidade, ponto de fusao, rendimento do processo e pH das gelatinas extraidas. Para a obtencao das gelatinas, as materias-primas foram submetidas a pre-tratamentos alcalino e acido, com posterior extracao por 12h a 45 oC. A viscosidade da gelatina de pele foi 1,13 cP e ossos 0,66 cP. O valor do ponto de fusao da gelatina de pele foi de 22,16 °C enquanto para gelatina de ossos 21 °C. A gelatina de pele apresentou um rendimento de processo (5,85%) consideravelmente maior que a de ossos (1,18%). O valor de pH das gelatinas foi semelhante.

The impact of the partial replacement of sodium chloride in the development of starter cultures during Italian salami production

Italian salami is a cured meat with high sodium contents which is easy, fast and convenient to consume. Starter cultures are used to improve its sensory characteristics and refine its technological manufacturing process. The goal of this study was to reduce the sodium content in Italian salami through the partial replacement of sodium chloride by potassium chloride, magnesium chloride and calcium chloride, and evaluate the viability of the Lactobacillus sp. and Staphylococcus sp. cells found in the starter culture. Four formulations were elaborated: one with, and one without the starter culture, but both with the addition of sodium chloride; and two with the partial replacement of 60% of the sodium chloride: the first with KCl, and the other with a mixture of KCl, MgCl2 and CaCl2. Physicochemical and microbiological evaluations were carried out to monitor the ripening and the quality of the final product. The partial replacement of NaCl by other salts (MgCl2, CaCl2, KCl) did not interfere in the growth of the starter culture in the Italian salami, neither did it affect the majority of the physicochemical parameters of the Italian salami nor the microbiological quality of the final product.