| Meat flavor is an important additive in meat products. It can effectively improve the lack of mellow feeling and delicate sense caused by the meat loss due the process. So, it plays an important role to the flavor of meat, and becomes one of the fastest growing types of food ingredients in recent years. However, as its main subjects are volatile aromatic oils, it makes the flavor not only easier to loss, which will increases the amount of use and short lasting, but a greater impact on the space environment odor. Besides, the effect of the environment (light, oxygen, temperature, etc.) will lead to the distortion or spoilage of the flavor. All of these above make the use and conservation of the flavor limited a lot. Well, thanks to the rapid development of microencapsulation technology, which allows flavor can be protected in the wall materials to overcome the drawbacks above, to reduce its volatility greatly, to prolong the retention of flavor, and easily to use, transport and store.There are many kinds of methods to prepare microcapsules, such as interfacial polymerization, solvent evaporation, emulsion polymerization, etc. This study chose complex coacervation combined with spray-drying to prepare meat flavor microcapsules and to characterize their physical and chemical properties. Complex coacervation is easy to control the operation, few reagents used, and can get uniform products.Well, spray-drying has great process capacity and can get continuous productions, Firstly, the main volatile aroma components of representative meat flavor such as pork, beef and so on were analyzed to evaluate their major contributions to the different meaty. Secondly, ethylmaltol which is the highest content was selected as a representation of the flavor to establish a method to measure the flavor microencapsulation rate. Thirdly, the experimental conditions of the complex coacervation reaction were optimized. After that, the effects of dispersion and emulsification of ultrasonic to the microcapsules form, the flavor retention and the sensory quality were explored. Finally, the stability of the microcapsules was investigated.1. Sulfur containing compounds, such as3-methylthio-propanol, furfuryl mercaptan, etc. in the flavor, were the main materials to produce basic meaty. Mesityl oxide, methyl cyclopentenolone, ethylmaltol, etc. can provide the flavor caramel odour.2-acetyl pyrazine was one of the typical representative of roasted flavor.2-acetyl furan and phenolic compounds had a smoky flavor. Anethole, eugenol and so on were important components of natural spices to provide spicy flavor. In addition, special compounds contributed to the three meat flavors characteristic flavor respectively, such as nonanal and other aldehydes in the pork flavor, bis (2-methyl-3-furyl) disulfide and a variety of sulfur containing compounds in the beef flavor, and benzaldehyde, methyl heptenone and other carbonyl compounds in the chicken flavor. Particularly, among the volatile aroma components in these three meat flavor, ethylmaltol had occupied the absolute advantage of the percentage. It can be soluble in alcohol, chloroform and other organic solvents, and formed a stable solution to be detected easily. Therefore, ethylmaltol can be chosen as an iconic ingredient to indicate the quality of flavor ingredients.2. The standard curve of ethylmaltol was drawed, and the content of ethylmaltol for this experiment was0.44%in the pork flavor. Then the measurement method of flavor microencapsulation rate was established, and the reaction conditions of complex coacervation were optimized as follows. The isoelectric point of gelatin was5.05. The optimal pH was4.00for the reaction. The best ratio of the wall materials, gelatin:sodium alginate was3:1and best wall core ratio was1:4. Under these conditions, pork flavor microcapsules had good forms showed by microscopic image, and the average embedding rate of the products can reach to89.29%.3. The results of ultrasound-assisted preparation of microcapsules showed that phacoemulsification can make the oil phase dispersed in the solution more evenly before the complex coacervation reaction, to get the microcapsules with good form, uniform size, and clear background. The orthogonal experiment won the best ultrasound conditions during the complex coacervation reaction, which are30min of time,45℃, and power20%(x950W). The major and minor relationship among the influencing factors was temperature> Power> Time. In addition, the flavor loss rate was determined after a period of storage. It showed that ultrasonic power of the process make the greatest influence on the loss rate of the surface flavor, the lower power, the higher loss rate. Well, the total loss rate of flavor is greatly influenced by the reaction time, the shorter time, the weaker intermolecular force between wall materials and easier to lose flavor.4. Flavor and microcapsules GC-MS analysis showed that microcapsules obtained by complex coacervation, whether it is dry or wet, can protect the internal flavor and delay the loss within a certain temperature range. Microcapsules prepared by different way are basically consistent with the flavor not embedded on the types and proportions of the main volatile components. In different storage environments, mechanical stress caused by vacuum packaging was easy to make the wall rupture, leading to the decrease of embedding rate. And the influence factors of retention rate were temperature> humidity> oxygen. Cool and dry was most conducive to the preservation of microcapsules. Also, it should be protected from high-strength extruded and other external force.β-cyclodextrin was able to combine some of the water molecules, providing a supporting role to protect the integrity of microcapsules form. SEM graph shows that, to some extent, ultrasound can reduce the particle size of the microcapsule and increase its uniformity. The sensory evaluation results also show that it is the best way to put the microcapsules under refrigerated condition with β-cyclodextrin added for maintaining their shapes. |
PDF Full Text Request