Effects of different drying methods on physicochemical properties of egg yolk powder
Abstract: spray drying, vacuum freeze drying, microwave drying equipment, infrared drying and hot air drying were used to study the effects of different drying methods on the physicochemical properties of egg yolk powder. The moisture content, thermal stability, color, emulsifying property and powder structure of yolk powder prepared by different drying methods were determined.
The results showed that the moisture content of egg yolk powder was the lowest (2.5%), and the moisture content of yolk powder was the highest (3.9%), and there was a significant difference between the two (P<0.05). The moisture content of yolk powder from these 5 drying methods was less than 4%, which accords with the current standard of egg products.
The yolk powder with hot air drying has the worst color (brightness is only 83.45), and the freeze-dried egg yolk powder has the highest emulsifying ability, while the spray drying egg yolk powder has the worst emulsifying ability. The egg yolk powder prepared by spray drying is spherical and uniform, while the other 4 kinds of dried egg yolk powder are massive. According to the above results, the physical and chemical properties of egg yolk powder are greatly affected by drying methods, and different drying methods can be adopted according to different requirements in actual production.
Special yolk powder for production.
Key words: drying method; microwave drying of yolk powder; physicochemical properties; powder structure
Egg yolk is about 28%~29% of egg weight, including egg yolk lecithin, low density lipoprotein, high-density lipoprotein, high vitelloprotein and other bioactive substances. Therefore, egg yolk has high nutritional value and multiple functional properties (such as emulsification, gelation, etc.).
After separating the yolk from the egg white, the yolk powder can be prepared by drying. The yolk powder contains about 30% protein, 38% glyceride and 19% phospholipids. In addition, there are a small amount of sugar, minerals, vitamins, pigments, enzymes and so on.
Compared with yolk liquor, yolk powder has the advantages of long shelf life, good functional stability, easy production, transportation and storage. Its uses include extracting lecithin in the pharmaceutical industry, using it in the food industry as mayonnaise, salad dressing, baking food, cold drinks (ice cream, ice cream) and auxiliary materials of full-price nutritional food.
In the production of egg yolk powder, it is necessary to remove water from the yolk liquid to make powder. At present, domestic and foreign scholars mainly focus on the extraction of emulsifying active ingredients in egg yolk and the modification of egg yolk. However, in the production of egg yolk powder, the effects of different drying methods on its physical and chemical properties have not been reported.
Therefore, 5 kinds of drying methods commonly used in the production of egg yolk powder (spray drying, vacuum freeze drying, hot air drying, infrared drying and microwave drying) were used to prepare egg yolk powder. The effects of different drying methods on the moisture content, thermal stability, color, emulsification and microstructure of yolk powder were studied in order to provide theoretical basis and technology for the production and processing of egg yolk powder. Operative support.