Estudios preliminares de la contribución de las fases lipídica y acuosa de una emulsión cárnica modelo a la percepción de aroma a carne
Meat aroma is composed of a wide variety of chemical compounds. It has been reported to be made of more than 700 chemicals. Among the most important reactions responsible of meat aroma are Maillard reaction and lipid autoxidation or oxidative rancidity. However, aroma perception is modified by the p...
| Autor: | |
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2007 |
| País: | México |
| Institución: | Universidad Autónoma Metropolitana |
| Repositorio: | Repositorio Institucional de la UAM Iztapalapa |
| Idioma: | español |
| OAI Identifier: | oai:bindani.izt.uam.mx:3n203z326 |
| Acceso en línea: | https://doi.org/10.24275/uami.3n203z326 |
| Access Level: | acceso abierto |
| Palabra clave: | info:eu-repo/classification/LEM/Carne -- Sabor y olor info:eu-repo/classification/LEM/Biotecnología info:eu-repo/classification/LEM/Productos cárnicos info:eu-repo/classification/LEM/Meat -- Odors -- Flavor info:eu-repo/classification/LEM/Emulsiones info:eu-repo/classification/LEM/Emulsions info:eu-repo/classification/LEM/Biotechnology info:eu-repo/classification/cti/6 |
| Sumario: | Meat aroma is composed of a wide variety of chemical compounds. It has been reported to be made of more than 700 chemicals. Among the most important reactions responsible of meat aroma are Maillard reaction and lipid autoxidation or oxidative rancidity. However, aroma perception is modified by the physical system where the odor-related compounds are trapped. Many food materials are emulsions; a number of meat products are considered being this type of physical system. Odor compounds must be soluble in the disperse or continuous phase, or both, due to the emulsion structure. Therefore, each phase contributes in a different way to the overall aroma of a meat emulsion. The objective of this work was to study the contribution of disperse and continuous phases of a model meat emulsion by analyzing the release of five aroma indicator compounds, and myofibrillar protein concentration and depletion in the phases. Hexanal, octanal and nonanal were taken as indicators of lipid oxidation whereas 1- ethyl-3,5-dimethyl pyrazine and 2-methyl pyrazine were Maillard reaction indicators. Four systems were studied: I) a model meat emulsion; II) phosphate buffer; III) phosphate buffer+myofibrillar proteins; IV) canola oil. Release of indicator compounds from each of the studied systems was analyzed in the headspace. In a further experiment, the extraction index of the five compounds were analyzed; the disperse (lipid) phase was extracted with methanol, whereas the continuous (aqueous phase) was extracted with chloroform. From preliminary tests, it was concluded that the two models better describing a meat emulsion were: Model I: pH 7.5 (fixed effect), protein extract (20, 25, 30 and 35%; Model II: 35% protein extract (fixed effect), pH (4.5, 5.5, 6.5 and 7.5). Emulsion capacity increased with protein concentration and pH; proteins were partially denatured during emulsion formation, increasing the ability to emulsify fats. The emulsion showed a monodisperse particle size distribution, decreasing the averge size as pH and protein concentration increased. A pseudoplastic behavior was observed as apparent viscosity decreased with increasing shear rate. When a commercial emulsifier was included in the formulation, scanning electron microscopy showed a more homogeneous particle size and high emulsion stability. Disperse phase fraction volume in both model emulsions increased with protein concentration and pH. As expected, protein concentration was higher in the continuous phase (phosphate buffer) than in the disperse phase (oil) due to their solubility in medium ionic strength solutions. However, actin was present in similar amounts in disperse and continuous phases, probably at the interface. The solid phase microextraction technique (SPME) showed that aldehyde release indexes (k) were the highest in the buffer system, with or without proteins, but considerably low in the lipid system; hexanal and nonanal had very low release indexes in the emulsion. Conversely, octanal had a high release index in the emulsion. Both pyrazines had very high release indexes in the protein solution (buffer+protein extract) and in the oil, but low in the emulsion and buffer without proteins. It was concluded that pyrazines mainly contributed to aroma in lipid systems and in protein solutions, but not in emulsions and non protein aqueous systems. Hexanal, octanal and nonanal were minor aroma contributors in lipid media. The solvent extraction technique showed that extraction indexes (kext) with methanol were considerable higher than with chloroform; octanal sowed the highest extraction index. The lowest index in the disperse phase (extracted with methanol) were for nonanal and 2-methyl pyrazine, whereas in the continuous phase (extracted with chloroform) were for nonanal y el hexanal. This method did not detect any difference between nonanal and 2-ethyl-3,5-dimethyl pyrazine indexes, and between hexanal and 1-ethyl-3,5-dimetil pyrazines; conversely as the results obtained with the SPME. Therefore, SMPE was more sensitive than solvent extraction method. |
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