Effect of ante-mortem hypoxia on the physicochemical and functional properties of white shrimp (Litopenaeus vannamei) muscle stored on ice.

The effect of ante-mortem hypoxia on the physicochemical and functional properties of raw and cooked white shrimp was studied. Hue angle was greater (p ≤ 0.05) for stressed raw shrimp compared to control (greener color); whereas a lower angle was detected for cooked stressed shrimp (redder/orange coloration). In addition, hue angle increased (p ≤ 0.05) over the ice storage period for control and stressed shrimp (raw and/or cooked). Muscle hardness and shear force showed no differences when comparing control and stressed shrimp (raw and/or cooked). However, during ice storage, shear force increased (p ≤ 0.05) by 22% and 9% for control and stressed raw shrimp, respectively; in contrast, shear force and muscle hardness decreased for cooked shrimp (p ≤ 0.05). Control showed more (p ≤ 0.05) elasticity than stressed cooked shrimp. Stressed raw shrimp showed a water holding capacity 10.8% lower (p ≤ 0.05) than control. However, during the storage, water holding capacity increased (p ≤ 0.05) reaching similar values to control after day 4. Muscle protein solubility of stressed shrimp was 31% lower than control; however, no differences (p > 0.05) were observed after the second day. The thermal stability of myosin (T max) showed differences (p ≤ 0.05) among control and stressed shrimp, whereas no differences for ΔH were observed. Results showed the influence of ante-mortem hypoxia on the physicochemical and functional properties of white shrimp muscle.

Partial characterization of an effluent produced by cooking of Jumbo squid (Dosidicus gigas) mantle muscle.

Jumbo squid (Dosidicus gigas) mantle muscle was cooked simulating industrial procedures (95 degrees C x 25 min, 1.2:5 muscle:water ratio). The effluent produced was analyzed for chemical and biochemical oxygen demands (COD and BOD(5), respectively), proximate analysis, flavor-related compounds (free amino acids, nucleotides and carbohydrates) and SDS-PAGE. The COD and BOD(5) exhibited variation among samplings (N=3) (27.4-118.5 g O(2)/L for COD and 11.3-26.7 g O(2)/L for BOD(5)). The effluent consisted of 1% total solids, 75% of which represented crude protein. Sixty percent of the total free amino acid content, which imparts flavor in squid species, corresponded to glutamic acid, serine, glycine, arginine, alanine, leucine and lysine. The nucleotide concentration followed this order, Hx>>ADP>AMP>ATP>IMP>HxR. The variation observed in the present work was probably due to physiological maturity differences among the squid specimens (i.e., juvenile versus mature). Solids present in squid cooking effluent could be recovered and potentially used as flavor ingredients in squid-analog production by the food industry.

Efecto de la concentración de quitosano y ph sobre la remoción de sólidos en agua de cola de la industria sardinera / Effect of chitosan concentration and ph on the removal of solids from stickwater produced in the sardine industry / Efeito da concentração de quitosana e ph sobre la remoção de sólidos em resíduos líquidos da indústria de sardinhas

El agua de cola es un efluente complejo compuesto por una gran variedad de sólidos, los cuales deben ser removidos en su mayor parte para generar un efluente que pueda ser vertido directamente al mar. En el presente estudio el agua de cola se centrifugó y posteriormente se trató con quitosano a distintos valores de pH y concentraciones con la finalidad de remover sólidos presentes. Mediante la centrifugación se logró remover el 33,88% de los sólidos totales; 28,52% de proteína; 97,50% de grasa; 40% de ceniza y 20% de NNP, y disminuyeron la DBO5 y la DQO en un 42,2 y 63,3% respectivamente. El porcentaje de transmitancia aumentó de 14,6 a 18,4 siendo éste un cambio pequeño en relación al contenido de sólidos removido. La adición de quitosano al agua de cola centrifugada redujo en 25% el contenido de sólidos totales, 55% el de proteína, 40% el de grasa, 24% el de cenizas y 60% el de NNP. De igual forma, disminuyó la DBO5 y la DQO en un 48,4 y 31,2% respectivamente. Como resultado de la adición el porcentaje de transmitancia aumentó de 18,4 a 86,0; indicando que tal aumento se debió principalmente a la remoción de pigmentos y no de materia orgánica. Se logró una disminución importante en DBO5 y DQO; sin embargo, se requieren otras herramientas para reducir estos valores a concentraciones establecidas en la reglamentación sanitaria.

The stickwater is a complex effluent consisting of a variety of solids, most of which should be removed to produce a new effluent that can be directly poured into the sea. In this study, stickwater was centrifuged to remove solids and the resulting liquid was then treated with chitosan at different concentrations and pH to eliminate the solids left in it. Centrifugation extracted 33.88% of total solids, 28.52% protein, 97.50% fat, 40% ash and 20% NPN. It also decreased in 42.2 and 63.3% the BOD5 and COD, respectively. Transmittance percent increased from 14.6 to 18.4, a small change in relation to the content of solids removed. The addition of chitosan to centrifuged stickwater decreased 25% of the total solids content, 55% of protein, 40% fat, 24% ash and 60% NPN. Likewise, the addition of chitosan decreased the BOD5 and COD in 48.4 and 31.2%, respectively. As a consequence, transmittance increased from 18.4 to 86.0%, indicating that such increase was mainly due to the elimination of pigments rather than organic matter. A significant decrease was achieved in BOD5 and COD; nevertheless, other tools are required to reduce these figures to the levels established by the environmental health regulations.

O residuo liquido (stickwater) é un efluente complexo composto por uma grande variedade de sólidos, os quais deven ser removidos principalmente para gerar un efluente que possa ser vertido diretamente ao mar. No presente estudo o residuo líquido foi centrifugado e posteriormente tratado com quitosana a distintos valores de pH e concentrações com a finalidade de remover sólidos presentes. Mediante a centrifugación se conseguiu remover 33,88% dos sólidos totais; 28,52% de proteína; 97,50% de gordura; 40% de cinza e 20% de NNP, e diminuiram a DBO5 e a DQO em 42,2 e 63,3% respectivamente. A porcentagem de transmitância aumentou de 14,6 a 18,4 sendo esta uma mudança pequena em relação ao conteúdo de sólidos removido. A adição de quitosana no residuo líquido centrifugado reduziu em 25% o conteúdo de sólidos totais, 55% o de proteína, 40% o de gordura, 24% o de cinzas e 60% o de NNP. De igual forma, diminuiu a DBO e a DQO em 48,4 y 31,2% respectivamente. Como resultado da adição, a porcentagem de transmitância aumentou de 18,4 a 86,0; indicando que tal aumento foi devido principalmente à remoção de pigmentos e não de matéria orgânica. Alcançou-se uma diminuição importante em DBO5 e DQO; no entanto, são requeridas outras ferramentas para reduzir estes valores a concentrações estabelecidas na regulamentação sanitária.