Proteins in catfish by-products were extracted by two methods: Alkaline extraction (AE) and salt extraction (SE). Properties of the fish protein isolate (FPI) were measured by protein yield and content, moisture content, SDS-PAGE protein patterns, color and texture profile, and compared with commercial surimi products. Our results showed that catfish frame had higher protein yield and color similarity with commercial products than the head; AE-FPI had higher yield and gel strength than SE-FPI; SDS-PAGE protein patterns of FPI from catfish frame by SE method was comparable with commercial surimi products. Based on the results, further optimization of the recovery yield of protein extracted by alkaline extraction method, and effect of microbial transglutaminase (MTGase) on gelation properties under various concentration and reaction time was investigated. Results indicate that the protein yield reached up to 60%, and the addition of MTGase in protein isolate effectively improved the gel forming ability.

Rice flour possesses functional properties in enhancing texture and whiteness. This study was carried out to evaluate rice flour as a functional ingredient for premium crabstick and to develop a commercially viable recipe for premium crabstick. Crabstick pastes were formulated with constant surimi (42%) and combined rice flour and starch (8%) concentrations. Rice flour concentration was varied (0, 1, 3, and 5%) in order to evaluate changes in physicochemical properties of crabstick pastes. The physical properties of cooked gels were measured during refrigerated and frozen storage. Rice pastes with various concentrations of rice flour (5 to 40%) mixed in water, demonstrated similar patterns for differential scanning calorimetry (DSC) with endothermic peaks at around 63.5°C. During refrigerated storage up to 21 days, gel strength increased gradually, while cohesiveness was not significantly changed (P>0.05). At 1% rice flour addition, fracture gel properties during 21 days of refrigerated storage showed optimum results. During frozen storage, water retention ability (WRA) gradually decreased as freeze-thaw (F/T) cycles were extended. However, the water loss was minimized as rice flour concentration increased. Two different crabstick samples (control and 1% rice flour) demonstrated no significant difference (P>0.05) in gel hardness and cohesiveness, respectively. Rice flour (1%) can, therefore, be used to replace various starches as a functional ingredient in premium crabstick formulations. / Graduation date: 2012

Surimi is a seafood product which is used to manufacture restructured products such as artificial crab and lobster. Surimi is produced from fish fillets by washing to remove sarcoplasmic proteins and increase the concentration of myofibrillar proteins, and mixing with cryoprotectants. A valuable attribute of surimi is its ability to form an elastic gel, the gel network being formed by the myofibrillar proteins of fish muscle. It is generally accepted that the quality of surimi gels is influenced by the activity of endogenous protease which acts on the myofibrillar proteins. The proteases in Pacific whiting surimi (Merluccius productus) are particularly problematic due to their high catalytic activity on muscle myosin. The addition of whey protein concentrate (WPC) to Pacific whiting surimi has been shown to enhance the gel strength of the corresponding products produced from this surimi. The mechanism through which WPC enhances the gel strength of Pacific whiting surimi has not been determined, but it has been suggested that WPC acts to inhibit surimi autoproteolysis. The objective of this study was to determine whether the incorporation of WPC into Pacific whiting surimi inhibits autoproteolysis and/or protects the myosin fraction from proteolytic degradation. The effect of supplementing surimi with WPC, beef plasma protein (BPP) and bovine serum albumin (BSA) on its apparent autoproteolysis activity was determined. Three WPC preparations were tested, WPC 34, 34% protein; WPC 80, 80% protein; and WPC 95, 95% protein. Each of the additives was incorporated at the 1, 2, 3 or 4% level. Proteolysis of surimi and supplemented surimi samples was allowed to occur at 55°C. Proteolytic reaction mixtures were terminated by the addition of trichloroacetic acid (TCA). Proteolytic activity was estimated by measuring the difference in TCA-soluble peptides present in reaction mixtures of paired (identical) samples, one having been incubated at 55°C while the paired sample was kept on ice. Peptides were quantified by the bicinchoninic acid, Lowry, dye-binding and trinitrobenzenesulfonic acid methods. Results based on the different peptide assays were compared in order to asses the reliance of results on specific assay methods. BPP was found to have the most inhibitory activity in the autoproteolysis assays, followed by the WPC preparations and then BSA. Autoproteolysis was completely inhibited by the incorporation of 1% BPP, 3% WPC 80 and 2% WPC 95. The extent of inhibition by the WPC preparations was related to their protein content, the higher the protein content the greater the extent of inhibition per unit weight added to surimi. BSA was not an inhibitor of autoproteolysis under the conditions used in this study. The relative extents of inhibition observed for the different additives were independent of the method used to quantify the soluble peptide products. Each of the additives was also tested for their ability to protect the myosin component of surimi from proteolytic degradation. These experiments were done as described above for the autoproteolysis assays with the exception that following the incubation period a portion of the sample, either surimi or a surimi/additive mixture, was completely solubilized in detergent solution, subjected to SDS-PAGE electrophoresis and visualized by protein staining. In these experiments the additives were incorporated at the 4% level. No apparent degradation of myosin could be detected over a 60 min reaction period for surimi samples that were supplemented with BPP, WPC 80 and WPC 95. In contrast, surimi samples incubated without additive clearly showed a loss of myosin after 15 min reaction period. Some myosin degradation was apparent following the 60 min incubation period for the WPC 34-supplemented surimi. A further experiment was conducted to determine the mechanism through which WPC protects myosin and inhibits autoproteolysis. In this experiment WPC 95 and BPP were separately incubated at 55°C with a crude fish protease preparation, i.e. the reaction mixture approximates that used in the autoproteolysis assays except that it contains no surimi. The results indicate that BPP and WPC 95 behave in a similar manner. However, the results were inconclusive with regard to explaining the additive's mechanism of action. Plausible mechanisms which are consistent with the results are discussed. / Graduation date: 1994

A novel method for isolating fish proteins by shifting pH to high acid or high alkali pH was the focus of the study. Biochemical and physicochemical properties of various pH-treated soluble fish proteins as a function of ionic strength were determined. Effect of ionic strength and various storage conditions on gelation properties and stabilization of fish protein isolate (FPI) were also elucidated. At low ionic strength (IS 10 mM NaCl), the solubility of Pacific whiting (PW) proteins was low between pH 5 and 10, but increased significantly as the pH was shifted to either acidic or alkaline pH. The isoelectric point (pi) shifted toward acidic direction as IS increased to 600 mM. High IS (600 mM NaCl) resulted in protein aggregation at low pH but improved myosin heavy chain (MHC) solubility at pH 6 - 10. Changes in total sulfhydryl (SH) content and surface hydrophobicity (S [subscript o]) were associated with the different molecular weight distributions of the soluble proteins. At pH 4 and IS 10-100 mM, MHC was soluble but degraded. At pH 10, the formation of high MW polymers was observed at IS [greater than or equal to] 150 mM. Gels obtained from FPI prepared at pHl1/IS150 and conventional surimi (CS) were superior to FPI prepared at pH 3 and/or other IS levels. There was no correlation between protein solubility and gel properties of FPI. Gelation mechanisms of acid and alkali-treated FPI were identical under the same IS condition. FPI prepared at pH 3 or 11 could be partly refolded at pH 7. No significant difference in texture was observed between alkali-treated protein isolates (AKPI, pH 11) kept frozen at pH 5.5 and 7.0. Strongest gel was found for AKPI with cryoprotectants (C) and without freeze/thaw (FT) cycles at both pH storage (5C & 7C), while poor gel was obtained from AKPI without cryoprotectants (NC) and with FT (5NC-F & 7NC-F). 5NC-F & 7NC-F demonstrated the lowest S [subscript o] and total SH probably suggesting that proteins were more aggregated as a result of hydrophobic interactions and disulfide bonds. Scanning electron microscope (SEM) revealed the most discontinuity of gels from AKPI without cryoprotectants and with FT and showed less protein stability when stored at pH 5.5 than at neutral pH. Raman spectral analysis demonstrated that refolding of AKPI by pH adjustment to 7.0 was achieved, but not identical to the native protein. CS contained higher α-helix content (~50%) than AKPI (~20-30%). Frozen storage induced a decrease and an increase in the α-helix of CS and AKPI samples, respectively. Alkali-treated proteins were slightly less stable than CS during frozen storage. / Graduation date: 2005

Proteolysis of myofibrillar proteins in Pacific whiting surimi occurs when the 50- 70°C temperature range is reached during standard cooking procedures (e.g. 90°C for 15 min). This proteolytic activity results in the softening of surimi gels. Bovine plasma protein (BPP) is the most effective of the food-grade inhibitors used to prevent this reaction, and enhance gel strength in PW surimi. The objective of this study was to determine the effective components of bovine plasma that enhance gel strength in PW surimi. Five bovine plasma fractions were evaluated for components that contribute to gel strength enhancement in PW surimi. Fraction I, which consists mostly of fibrinogen and albumin, was found to also contain plasma transglutaminase (PTGase) activity. Part of fraction I gel-enhancing ability may be attributed to an unknown component which inhibited papain independently of Ca²⁺ and inhibited 40% of surimi proteolytic activity. Fibrinogen or albumin did not inhibit papain activity or enhance gel strength of surimi. For fraction I-S, which is a more concentrated PTGase fraction, gel-enhancement of PW surimi was completely dependent on the presence of Ca²⁺. Autolytic inhibitory activity of fraction I-S in surimi was completely eliminated by the presence of Zn²⁺. Fraction II+III (1%) inhibited over 50% of surimi autolytic activity and displayed a small amount of PTGase activity. Fraction II+III (1%) gel enhancing abilities were low when compared to the other fractions and BPP, and only slightly effected by EGTA. Fraction IV (1%), which contains approximately 50% albumin and 15% α₂-macroglobulin, inhibited over 70% of surimi autolytic activity. It enhanced gel strength at a 1% (w/w) concentration when set for 20 hr at 4°C before cooking, and was not affected by EGTA. This fraction displayed no apparent PTGase activity. Fraction IV-1 (1%), which contains approximately 20-30% α₂-macroglobulin, gel strength enhancement surpassed the other fractions and BPP when set for 20 hr at 4°C and 2 hr at 25°C before being cooked at 90°C for 15 min. The gel strength enhancing abilities of fraction IV-1 were significantly affected by EGTA. Fraction IV-1 (1%) inhibited over 80% of surimi proteolytic activity. The gel strength of 1 mM (0.03%) E-64, which is a cysteine protease inhibitor, was equivalent to that of BPP (1%) after setting at 4°C for 20 hrs before cooking. E-64 (1 mM) inhibited 83% of the autolytic activity of PW surimi and BPP (1%) inhibited 78%. These data indicate that a cysteine protease inhibitor can increase gel strength, and suggests that BPP is acting as a cysteine protease inhibitor. Ca²⁺ dependent gel strength enhancement was attributed to transglutaminase (TGase) activity, both added PTGase and endogenous TGase. Gel strength enhancement that was Ca²⁺ independent was attributed to cysteine protease inhibitors, specifically α₂-macroglobulin. Overall, it was determined that gel strength in PW surimi was greatly enhanced by both concentrated PTGase (I and I-S) and concentrated α₂-macroglobulin (IV-1) fractions, with a combination of these fractions being most effective in gel strength enhancement, when the surimi is first set at 4°C or 25°C before cooking at 90°C for 15 min. These data suggest that the mechanisms of gel strength enhancement of BPP are from cysteine protease inhibition, possibly from α₂-macroglobulin, and from crosslinking of myosin in surimi from both added (PTGase) and endogenous TGase activity. / Graduation date: 1996

Graduation date: 1993

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias. Programa de Pós-graduação em Ciência dos Alimentos / Made available in DSpace on 2012-10-22T04:14:30Z (GMT). No. of bitstreams: 0 / O surimi pode ser definido como um concentrado de proteínas miofibrilares produzido a partir de carne de peixe moída lavada, adicionada de crioprotetores para melhor conservação, e congelada em blocos. Uma das propriedades mais apreciadas do surimi é sua alta capacidade de formação de géis. As características do Kamaboko, gel obtido a partir do surimi pela adição de sal e amido e posterior cocção, são utilizadas como referência da qualidade do surimi. Neste trabalho o surimi foi processado de duas diferentes formas a partir da carne moída de peixe, sendo uma denominada de tradicional e outra precipitação isoelétrica (pI), diferenciados na etapa de lavagem., onde a pI sofre adição de ácido para redução do pH do meio ao pI da carne (5,3), ocasionando a precipitação das proteínas). A partir dos surimis tradicional e pI elaborou-se os Kamabokos. Determinaram-se a capacidade de retenção de água e composição centesimal dos diferentes kamabokos e estes foram analisados sensorial e instrumentalmente pelo método do perfil de textura (TPA). Para a textura realizaram-se as análises sensorial e instrumental, através de equipe treinada e em texturômetro TA-XT2, respectivamente. Avaliaram-se os parâmetros elasticidade, dureza, adesividade, mastigabilidade, gomosidade. Os resultados de textura sensoriais e instrumentais foram comparados e correlacionados através da análise de componentes principais (PCA). A elasticidade apresentou baixo grau de correlação com os demais parâmetros avaliados, porém apresentou boa correlação entre si. Os demais parâmetros apresentaram alto grau de correlação. Os dados de composição centesimal e capacidade de retenção de água foram analisados através da análise de variância (ANOVA - proposto por Fischer), seguida do teste de Tukey quando houve diferenças significativas entre as amostras. Para a análise de composição, a percentagem de proteínas dos diferentes kamabokos elaborados, bem como a capacidade de retenção de água, apresentaram níveis de diferença superiores a 100%. O rendimento final do surimi elaborado através de processamento por precipitação isoelétrica foi 20% maior em relação ao surimi elaborado por processamento tradicional.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias. Programa de Pós-Graduação em Ciência dos Alimentos. / Made available in DSpace on 2012-10-22T06:01:02Z (GMT). No. of bitstreams: 0 / Foram desenvolvidas três formulações de hambúrguer de peixe, utilizando diferentes tipos de amido (mandioca nativa, milho ceroso e mandioca modificada) para determinar diferenças texturiais nestas amostras através da análise de perfil de textura (TPA) sensorial e instrumental. Na sequência, as variáveis sensoriais e instrumentais foram correlacionadas utilizando o método de regressão dos mínimos quadrados (PLS). O resultado da análise de perfil de textura instrumental da amostra de hambúrguer de peixe utilizando amido de mandioca modificada, caracterizou-se pelos atributos dureza, gomosidade, mastigabilidade e elasticidade diferentes das duas outras amostras analisadas. Para a análise de perfil de textura sensorial, as amostras de hambúrguer de peixe utilizando amido de milho ceroso e mandioca modificada caracterizaram-se pelos atributos dureza e elasticidade. A correlação sensorial e instrumental resultou em uma correlação positiva para atributo dureza instrumental com os atributos sensoriais de textura, como, dureza, elasticidade, gomosidade e mastigabilidade, contribuindo desta forma, para a percepção da dureza durante a mastigação do hambúrguer de peixe. A segunda parte deste trabalho foi realizar um estudo de viabilidade econômica da produção de hambúrguer de peixe, utilizando os métodos de valor presente líquido (VPL) e taxa interna de retorno (TIR). O projeto para produção de hambúrguer de peixe apresentou ser viável economicamente, com um retorno bastante satisfatório.

Least cost formulations for surimi seafood were studied by linear programming (LP) and nonlinear programming (NLP). The effects of water and starches on functional properties of Alaska pollock and Pacific whiting surimi gels were investigated. Six starches (modified potato starch, potato starch, modified wheat starch, wheat starch, modified waxy corn starch, and corn starch) and their mixtures were used as ingredients. Mixture and extreme vertices design were used as experimental designs. Canonical models were applied to the optimization techniques. Blending different kinds of surimi showed linear trends for each functional property, so that LP was successfully employed to optimize surimi lots. Strong interactions were found between surimi and starch or in starch mixtures. Two optimum solutions, obtained from LP and NLP, were compared in this study. Corn starch and modified waxy corn starch greatly improved the functional properties. / Graduation date: 1997

Made available in DSpace on 2014-06-11T19:30:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-16Bitstream added on 2014-06-13T19:00:43Z : No. of bitstreams: 1 fogaca_fhs_dr_jabo.pdf: 1949132 bytes, checksum: 05710f824c05c437e276a4d91a9a839a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / O surimi é uma carne de pescado, submetida a lavagens sucessivas, onde se eliminam gordura, sangue, substâncias odoríferas e proteínas solúveis em água, resultando em uma pasta branca, sem odor e sabor característicos de peixe, permitindo melhor aproveitamento do pescado e dos resíduos gerados pelo processamento dos peixes. O estudo teve o propósito de caracterizar o surimi de tilápia nilótica, determinando suas características morfológicas, físicas, químicas e sensoriais. A partir de ensaios prévios foi delineado um planejamento experimental baseado na metodologia da superfície de resposta, composto por duas variáveis independentes: número de lavagens da carne mecanicamente separada - CMS (uma, três ou cinco) e porcentagem de adição de amido de mandioca (zero, 10 ou 20%). As variáveis respostas foram: força de cisalhamento (FC) e umidade (U %), pois estão diretamente correlacionadas com a qualidade fmal do surimi. Os resultados mostraram efeito linear da adição de amido e do número de lavagens na umidade do surimi, sendo que o tratamento com 10% de amido de mandioca e três lavagens da CMS apresentou os melhores valores. A FC apresentou diferença entre os tratamentos, não sendo possível definir um tratamento com melhor textura segundo os parâmetros avaliados. Os parâmetros físicos e químicos: pH, atividade de água, degradação lipídica e proteica, composição centesimal, cor, e o rendimento foram determinados para o surimi elaborado com: I) uma lavagem da CMS, 2) cinco lavagens da CMS, 3) uma lavagem e 20% de amido de mandioca, 4) cinco lavagens e 20% de amido de mandioca e 5) três lavagens e 10% de amido de mandioca, segundo a metodologia da superfície de resposta. O rendimento do surimi foi alto devido à capacidade de retenção de água do produto durante o processamento. As análises de pH e Aa não... / Surimi is a fish protein concentrate, submitted to successive washings, for removing fat, blood, odorous substance and water soluble protein, resulting in a white paste, without fish characteristic (odor and flavor), allowing better exploitation for fishes and their industrials residues. The objective of this study was tilapia surimi characterization, through the morphology, sensorial and physicochemical properties determination. From previous works, a central composite designs was modelled, with two independent variables: numbers of washings (1, 3 or 5) and cassava starch addition (zero, 10 or 20%), baseaded on the response surface methodology. The response variables were: moisture (%) and breaking force (FC) directIy correlated with the good quality of surimi. The results showed a linear effect of cassava starch addition and minced washing cycles. The treatment with 10% of cassava starch and three minced washings showed the better response variables. The FC showed differences between treatments, but wasn't possible to define a better treatment for texture analysis. The physic and chemical parameters: pH, Wa, lipid and protein oxidation, centesimal composition, color and surimi yield were determinated for surimi treatments: 1) one minced washing cycle, 2) tive minced washing cycles, 3) one washing cycle and 20% of cassava starch addition, 4) tive washing cycle and 20% of cassava starch addition and 5) three washing cycle and 10% of cassava starch addition. The surimi yield was higher due to the high water retention capacity of surimi during the washing processing. The pH and water activity analysis showed no differences between the treatments. The chemical composition was different for tilapia minced and surimi, the minced showed lower protein and lipid levels caused by washing of the minced. Treatments with 20% of cassava starch showed lower protein and lipid concentration... (Complete abstract click electronic access below)