Caracterização do surimi de tilápia do Nilo: morfologia e propiedades físicas, químicas e sensoriais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Hidrolisados protéicos de anchoita (engraulis anchoita): obtenção, atividade antioxidante e aplicação em embutido emulsionado

Uma alternativa para pescados subaproveitados e subprodutos da industrialização de pescado é o desenvolvimento de processos para recuperação e/ou alteração das proteínas musculares de pescados. O objetivo deste trabalho foi a obtenção de hidrolisados protéicos de carne mecanicamente separada (CMS) de anchoita (Engraulis anchoita) e a avaliação da sua atividade antioxidante, aplicando-os bem embutido preparado com o surimi de anchoita. Foram produzidos diferentes hidrolisados com as enzimas microbianas Alcalase, Flavourzyme e Protamex, fixando a concentração de substrato e de enzima e os parâmetros pH e temperatura foram variados. Os hidrolisados foram efetivos contra a inibição da peroxidação lipídica (43,8±0,2%) e no poder redutor, onde o hidrolisado com a enzima Flavourzyme em 1 hora de reação mostrou-se mais efetivo. No seqüestro de radicais livres, como o DPPH, o hidrolisado com a enzima Flavourzyme, obtido em tempo de hidrólise de 5 horas, alcançou valores acima de 45,0% em concentração de 5 mg/mL. Na produção de surimi foram testadas lavagens da CMS de anchoita com soluções de bicarbonato de sódio 0,5%, ácido fosfórico 0,05% e cloreto de sódio 0,3%. O maior rendimento (90,5%) e uma coloração mais clara (W= 50,24±1,81) foram encontrados no surimi obtido por lavagens com bicarbonato de sódio e cloreto de sódio (BS), em comparação ao surimi que se utilizou água, ácido fosfórico e cloreto de sódio (AF) ou com soluções de cloreto de sódio, ácido fosfórico e bicarbonato de sódio (AB). Na força de gel o surimi AF (1154,25 ± 4,37 g.mm) obteve maior valor, sendo utilizado para a produção de salsichas. Foram analisadas diferentes concentrações de surimi (70, 75 e 80%) em salsichas, que foram submetidas às análises de cor e textura. Não houve influência da concentração de surimi nas características tecnológicas da salsicha, exceto nos valores de luminosidade. A salsicha com 75% de surimi de anchoita foi caracterizada pela composição proximal, valor energético total (VET) e conteúdo de sódio. A salsicha com surimi e comercial apresentou composição semelhante. O produto com surimi apresentou menor VET (193,7Kcal/100g) e conteúdo de sódio (520 mg/100g) que a salsicha comercial. Nas condições de estudo, no embutido emulsionado, não foi verificada ação antioxidante de hidrolisados, porém houve efeito sobre a CMS de anchoita.

Suitability of sodium lactate as cryoprotectant and its effect on gel forming ability and protein denaturation of croaker fish surimi during frozen storage

The effect of sodium lactate is compared with sucrose + sorbitol + sodium tri-poly phosphate as cryoprotectant on gel forming ability & protein denaturation of croaker surimi during frozen storage at -20±2°C for 90 days was evaluated. The quality of Croaker surimi with 6% (w/v) sodium lactate was examined in terms of biochemical parameters of muscle protein, thaw drip, gel strength and calcium ATPase activity :.omparing with those of surimi added with sucrose/sorbitol & without additive as control. Both the cryoprotectants minimized the negative effects of frozen storage on physico-chemical traits of myofibrillar proteins which was evident from the biochemical and sensory parameters. The residual Ca2+ ATPase activity and gel strength of surimi with sodium lactate were higher than those of control throughout 90 days of storage. Ca2+ A TPase activity and gel strength found a high positive correlation. From the results, it was found that sodium lactate was equally effective in preservation of croaker muscle protein native structure during frozen storage as the sucrose/ sorbitol and also less sweet without any risk of maillard browning.

Inhibition of Protease Activity in Muscle Extracts and Surimi from Pacific Whiting, Merluccius productus, and Arrowtooth Flounder, Atheresthes stomias

Muscle extracts of Pacific whiting, Merluccius productus, and arrowtooth flounder, Atheresthes stomias, were assayed for proteolytic activity using azocasein as a substrate. Pacific whiting extracts showed maximum activity at pH 5.0-5.2 and a temperature of 50°C, while arrowtooth flounder extracts had maximum activity at pH 5.5 and 55°C. Three sources of inhibitors (potatoes, egg white, beef plasma protein) were evaluated in vitro for inhibition of protease activity. All three were found to be effective inhibitors in crude muscle extracts. Further studies utilizing these inhibitors in surimi showed that potato was equivalent to both egg white and beef plasma protein in preserving the gel forming characteristics ofheated kamaboko in both species.

Surimi based dried fish cake

Minced fish prepared from the fillets of the sciaenid fish (Lutjanus sp.) was washed with cold water (<10 °C) three times. The washed muscle was pressed through a piece of fine cloth to a moisture content around 80%. The pressed cake (Surimi) was ground with 2.5% sodium chloride and 3% tapioca starch. The mixed material was shaped in the form of a cake and left for one hour for the gel to set. The cakes were then steamed. The cooled cakes were cut into pieces of 1 cm length x 1 cm width x 0.5 cm thick. The pieces were either dried in an electrical oven at 50°C or dried in sun to a moisture content of 11-12%. Biochemical, bacteriological and organoleptic evaluation revealed that the cakes were in very good acceptable form for 8 months. The cakes could be rehydrated by soaking in water at ambient temperature for half an hour and boiling in water for 10 minutes.

The 66 k-Da protein identified as a light meromyosin is involved in the setting of surimi

The 66 kilo-Dalton (k-Da) protein split off from the cross linked myosin heavy chain (CMHC) formed due to the setting of Alaska pollack surimi, frozen-storage of Pacific cod flesh, and vinegar-curing of Pacific mackerel mince was identified as a light meromyosin (LMM). Puncture and stress-relaxation tests showed that the actomyosin subunits (AMS) of Alaska pollack surimi, upon setting at 30°C, transformed into gel, although the elasticity of this gel was very low when compared to the gels from surimi or actomyosin (AM). Electrophoretic studies showed that the band due to LMM in the gel from AMS gradually disappeared with the progress of setting but higher molecular weight polymer did not form. The intensity of the bands due to other myosin sub-fragments decreased a little. The findings suggest that at setting temperature, LMM of MHC molecule leads to an unfolding resulting in an intramolecular aggregation through non-covalent interactions, and thus plays a significant role in the crosslinking of MHC.

Role of transglutaminase-mediated cross-linking of protein in the temperature-dependent setting of Alaska pollack surimi

During the low temperature setting of fish paste, myosin heavy chain (MHC) is polymerized to cross-linked myosin heavy chain (CMHC), which is considered to occur by the action of endogenous transglutaminase (TGase). In this study the contribution of TGase on the setting of Alaska pollack surimi at different temperatures was studied. Alaska pollack surimi was ground with 3% NaCl, 30% h2o and with or without ethylene glycol bis (β-aminoethylether) N, N, N¹,N¹- tetra acetic acid (EGTA), an inhibitor of TGase. Among the pastes without EGTA, highest TGase activity was observed at 25°C but breaking force of the gel set at 25°C was lower than that set at 30°, 35°, and 40°C. Addition of EGTA (5m mol/kg) to the paste suppressed TGase activity at all setting temperatures from 20° to 40°C. Gelation of the pastes and cross-linking of MHC on addition of EGTA were suppressed completely at 20° and 25°C, partially at 30° and 35°C, and not at all at 40°C. The findings suggested that during the setting of Alaska pollack surimi TGase mediated cross-linking of MHC was strong at around 25°C but the thermal aggregation of MHC by non-covalent bonds was strong at above 35°C. Setting of surimi at 40°C and cross-linking of its MHC did not involve TGase.

Study of physicochemical, microbial and sensory properties of surimi produced from black mouth croaker (Atrobucca nibe) at freezing condition (-18ºC)

Black mouth croaker (Atrobucca nibe) is considered as a new valuable fish stock in the Oman Sea. In this study, surimi was manufactured from nonmarket size of the fish, manually and different cryoprotectant agents were added to the surimi. Finally changes in physiochemical, microbiological and sensory quality, characteristics of the surimi and kamaboko gel samples were assessed during 6 months at freezing storage (-18ºC). Surimi samples with the addition of Iranian tragacanth gum (TG), xanthan gum (XG), chitosan (CS) and whey protein concentrate (WPC) at 1% (w/w) were prepared to evaluate their impacts as a cryoprotectant on the surimi, individually. The results showed that the whiteness and lightness indexes in all surimi samples were gradually decreased during frozen storage. This trend of decreasing was more intensity in the control sample from 61.08±0.131 to 54.21±0.067 was recorded (p<0.05). Water holding capacity (WHC) in all treatments was decreased during 6 months. The lowest WHC (g/g) was obtained in the surimi without cryoprotectants and maximum WHC was measured in Tcs and Twpc samples, respectively (p<0.05). The lowest breaking force was calculated in Txg (166.00±22.627 g) and Tc (271.50±263.16 g) during 6 months at frozen storage, respectively (p<0.05), while Twpc treatment with slight variations showed the highest breaking force (p<0.05). Also, the lowest gel strength was obtained in Txg (68.22±6.740 g.cm) after 6 month of frozen storage (p<0.05). All Kamaboko surimi gels texture profile analysis parameters decreaced with increasing shelf life. This decreasing trend in the control sample was more severe. Floding results were reduced in all samples during storage (p<0.05). The best protective results probably were obtained in WPC, chitosan and commercial cryoprotectant agents, respectively due to protein stabilization of myofibrillar proteins and the protein-protein network structure, leading to the formation of surimi gel with strong textural properties during frozen conditions. The average number of surimi polygonal structures were significantly decreased (number per mm2) and their area were significantly increased (μm2) in all treatments (p<0.05). With increasing storage time, moisture, protein contents and pH were decreaced. Maximun TVB-N index was calculated in Tc (7.93±0.400 mg/100g) and Txg (7.88±0.477), respectively (p<0.05). TBRAs index was increased in all treatments during frozen storage, while this trend was reached in maximum value in Tc (p<0.05). Sensory evaluation of the fish finger quality characteristics (color, odor, texture and overall acceptability) preapare from frozen black mouth croaker surimi was decreaced during 6 month frozen storage. After the period of frozen storage the highest quality scores were measured in Twpc, Tcs and Tcc samples, respectively (p<0.05). In this study, coliform bacteria were not found in all treatments during frozen storage. The surimi sample containing chitosan showed lower mesophilic and psychrotropic bacteria (log cfu/g) than other treatments during frozen storage (p<0.05). Salt-soluble proteins extractions of all treatments were decreased during frozen storage. This decreacing trend was highest in Tcs (45.74±0.176%) and lowest in Tc treatments after 6 month of frozen storage (29.92±0.224%) (p<0.05). Although commercial cryoprotectant agents were successful in limiting the denaturation of proteins but sugar contents were not accepted for diabetics or those who disagree with the sweet taste and high calorie food. Hence, commercial cryoprotectant agents can be replaced with whey protein concentrate and chitosan at 1% level (w/w) consider that they were showed proper protection of the surimi myofibrillar proteins during storage.

Biochemical and Storage Characteristics of Myofibrillar Protein ( Surimi ) from Freshwater Major Carps

School of Industrial Fisheries, Cochin University of Science and Technology

Rheological characteristics of suwari and kamaboko gels made of surimi from Indian major carps

The gel strength, compressibility and folding characteristic of suwari (set) and kamaboko (set and cooked) gels prepared from rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) surimi were examined to understand the occurrence of suwari and modori phenomena in surimi from major freshwater carps. Suwari setting of gels did not take place at lower temperatures. Suwari gels showed good gel strength at 50 °C for rohu and at 60 °C for catla and mrigal after 30 min setting time. Incubation for 60 min decreased the gel strength at 60 °C for rohu and catla. Setting at 25 °C followed by cooking at 90 °C increased the gel strength. Increased setting temperature, however, decreased the gel strength of cooked gels. Gel strength and compressibility data were supported by folding characteristics.

Rheological characteristics of suwari and kamaboko gels made of surimi from Indian major carps

The gel strength, compressibility and folding characteristic of suwari (set) and kamaboko (set and cooked) gels prepared from rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) surimi were examined to understand the occurrence of suwari and modori phenomena in surimi from major freshwater carps. Suwari setting of gels did not take place at lower temperatures. Suwari gels showed good gel strength at 50 C for rohu and at 60 C for catla and mrigal after 30 min setting time