RESUMO
Greening of tuna metmyoglobin (MetMb) by thermal treatment (TT) and free cysteine is associated with sulfmyoglobin (SulfMb) production. This greening reaction (GR) was once thought to occur only in tuna species. However, recent research has revealed that not all tuna species exhibit this behavior, and it can also occur in horse MetMb. Thus, the present study aimed to compare the GR-reactive (Katsuwonus pelamis and Equus caballus) and GR-unreactive (Sarda chiliensis and Euthynnus lineatus) MetMb using UV-vis spectrometry during TT (60 °C/30 min and free cysteine) to monitor the GR. We used molecular dynamics (MD) simulation to assess the stability of the heme group during TT. We discovered that using GR-unreactive MetMb resulted in an incomplete GR without producing SulfMb. Additionally, our MD simulations indicated that Met85 presence in the heme cavity from GR-unreactive is responsible for the heme group instability and displacement of distal His during TT.
Assuntos
Temperatura Alta , Simulação de Dinâmica Molecular , Mioglobina , Atum , Animais , Mioglobina/química , Cavalos , Proteínas de Peixes/química , Heme/químicaRESUMO
Proteolytic enzymes are widely distributed in nature, playing essential roles in important biological functions. Recently, the use of plant proteases at the industrial level has mainly increased in the food industry (e.g., cheesemaking, meat tenderizing, and protein hydrolysate production). Current technological and scientific advances in the detection and characterization of proteolytic enzymes have encouraged the search for new natural sources. Thus, this work aimed to explore the milk-clotting and proteolytic properties of different tissues of Vallesia glabra. Aqueous extracts from the leaves, fruits, and seeds of V. glabra presented different protein profiles, proteolytic activity, and milk-clotting activity. The milk-clotting activity increased with temperature (30-65 °C), but this activity was higher in leaf (0.20 MCU/mL) compared with that in fruit and seed extracts (0.12 and 0.11 MCU/mL, respectively) at 50 °C. Proteolytic activity in the extracts assayed at different pH (2.5-12.0) suggested the presence of different types of active proteases, with maximum activity at acidic conditions (4.0-4.5). Inhibitory studies indicated that major activity in V. glabra extracts is related to cysteine proteases; however, the presence of serine, aspartic, and metalloproteases was also evident. The hydrolytic profile of caseins indicated that V. glabra leaves could be used as a rennet substitute in cheesemaking, representing a new and promising source of proteolytic enzymes.
Assuntos
Apocynaceae/enzimologia , Leite/química , Peptídeo Hidrolases/química , Folhas de Planta/enzimologia , Proteínas de Plantas/química , Proteólise , Sementes/enzimologia , Animais , Concentração de Íons de HidrogênioRESUMO
Jumbo squid (Dosidicus gigas) muscle proteins show low functionality with limited use in gel products. This work aims to assess the influence of adding the natural and commercially available fibre, amidated low-methoxyl pectin (at 0.5, 1.0, 1.5, 2.0 and 3.0%), on the physicochemical and functional characteristics of jumbo squid (Dosidicus gigas) mantle muscle gels. The addition of 0.5% fibre showed an immediate effect on the gel texture profile analysis, improving hardness (p<0.05) from (3.4±0.7) N of the control (no added fibre) to (5.2±0.9) N, and increasing elasticity (p≥0.05). Shear force was significant only at 3.0% fibre addition. Water holding capacity also improved (p<0.05) with fibre addition (from 75% in the control to 90-95% after the treatments). Whiteness was affected (p<0.05) when 3.0% fibre was added. Differential scanning calorimetry showed two endothermic transition peaks in the gels. The second peak (actin) increased (p<0.05) by 1-2 °C with fibre addition. Therefore, the present study demonstrates that amidated low-methoxyl pectin (0.5-3.0%) is an excellent ingredient to improve jumbo squid mantle muscle protein functionality, increasing the gel texture and water retention characteristics.
RESUMO
Summary Anamnesis: eight Silla Argentina breed horses imported from Argentina presented with an abnormal gait and skin lesions. Clinical and laboratory findings: all cases showed different degrees of hind limb hyperflexion, atrophy of the lateral digital muscles, skin lesions, and poor body condition. They underwent several clinical and laboratory examinations, including endoscopy of the upper respiratory tract, skin and liver biopsy, blood count, biochemical profile, and electromyography that showed evidence of a neuropathy and dermatitis. Treatment approach: the horses were treated with phenylbutazone and thiamine. The response was patient dependent with different degrees of recovery resulting. Conclusion: this is the first report of an outbreak of bilateral Australian Stringhalt in Colombia and the first associated to skin lesions according to the veterinary medicine scientific literature.
Resumen Anamnesis: ocho caballos de raza silla Argentina importados de Argentina presentaron un andar anormal y lesiones de piel. Hallazgos clínicos y de laboratorio: todos los animales presentaron hiperflexión de los miembros anteriores de forma bilateral, en diferentes grados de severidad; atrofia del músculo digital lateral, lesiones de piel y condición corporal deficiente. Se realizaron endoscopias, biopsias de piel, hematología, química sanguínea, electromiografías que indicaron una neuropatía y dermatitis. Abordaje terapéutico: los caballos fueron tratados con fenilbutazona y tiamina, con una respuesta variable entre los animales. Conclusión: este es el primer reporte de un brote de arpeo australiano en Colombia y el primero asociado a lesiones de piel de acuerdo a la literatura científica médico-veterinaria.
Resumo Anamnese: oito cavalos de raça Silla Argentina foram importados a partir da Argentina por una marcha anormal e lesões cutâneas. Achados clínicos e de laboratório: todos os animais apresentaram hiperflexão bilateral dos membros anteriores com diferentes graus de gravidade; atrofia do músculo digital lateral, lesões de pele e condição corporal baixa. Foram efectuadas endoscopias, biópsias de pele, hematologia química sanguínea e electromiografias que indicaram uma neuropatia e uma dermatitis. Abordagem terapêutica: os cavalos foram tratados com fenilbutazona e tiamina obtendo uma resposta variável entre os animais. Conclusão: este é o primeiro relatório de arpejo Australiano reportado na Colômbia e o primeiro associado com lesões de pele de acordo com a literatura científica médico-veterinária.
RESUMO
Conformational and thermal-rheological properties of acidic (APC) and neutral (NPC) protein concentrates were evaluated and compared to those of squid (Dosidicus gigas) muscle proteins (SM). Surface hydrophobicity, sulfhydryl status, secondary structure profile, differential scanning calorimetry and oscillatory dynamic rheology were used to evaluate the effect of treatments on protein properties. Acidic condition during the washing process (APC) promoted structural and conformational changes in the protein present in the concentrate produced. These changes were enhanced during the heat setting of the corresponding sol. Results demonstrate that washing squid muscle under the proposed acidic conditions is a feasible technological alternative for squid-based surimi production improving its yield and gel-forming ability.
Assuntos
Decapodiformes/química , Manipulação de Alimentos/métodos , Proteínas Musculares/química , Alimentos Marinhos/análise , Animais , Varredura Diferencial de Calorimetria , Concentração de Íons de Hidrogênio , Músculos/química , ReologiaRESUMO
Several proteases from plant sources have been proposed as milk coagulants, however, limited research has been done on their milk-clotting properties. The effect of temperature on the milk-clotting activity of kiwi fruit, melon and ginger extracts was evaluated, as well as the effects of the different extracts on curd properties. Melon extracts showed high milk-clotting activity over a broad temperature range (45-75 °C) while kiwi fruit and ginger extracts showed high activity over a narrower temperature range, with a maximum at 40 and 63 °C, respectively. Curds produced using kiwi extracts had textural properties comparable with those obtained using commercial rennet, while melon extracts produced a fragile gel and low curd yield. The milk-clotting behavior of the three plant extracts was related to the protease specificity present in these extracts. The kiwi proteases displayed chymosin-like properties and thus hold the best potential for use as a milk coagulant in cheese production.
Assuntos
Actinidia/química , Queijo/análise , Cucurbitaceae/química , Aditivos Alimentares/química , Leite/química , Extratos Vegetais/química , Zingiber officinale/química , Animais , Bovinos , Concentração de Íons de Hidrogênio , TemperaturaRESUMO
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.