Animal fats and fats contain a variety of fatty acids, nutrients, and special flavor components [1], but due to the characteristics of oils and fats, such as unsaturated fatty acids, which are unstable in light, heat, and oxygen environments, they will cause oxidative deterioration of oils and fats [2, 3], and improper storage or transportation will lead to the loss of nutrients.
In addition, the range of applications of oils is limited because they are insoluble in water and are not easily added uniformly to a variety of foods, so microencapsulation technology has been introduced into oils and fats to prepare stable powdered oils and fats [4].
What is Powder Grease
Powdered grease is an oil-in-water (OW) product [5], which is a granular or powdery product made of oil as the core material, protein, carbohydrate, emulsifier, gel, etc. as the wall material, using microencapsulation technology, high-pressure homogenization, and spray drying.
Powdered oils and fats not only maintain the inherent biological functional properties of oils, but also make up for their shortcomings, because they are less affected by the external environment, have strong storage stability, and have good water solubility and dispersibility, which helps to improve food organization and facilitate carrying and transportation [6].
Preparation method of powder grease
The preparation methods of microencapsulated powdered greases can be divided into three categories according to their properties: physical, chemical, and physicochemical methods [7]. Among them, physical methods include spray drying and freeze-drying, chemical methods include in-situ polymerization and interfacial polymerization, and physicochemical methods include dry bath and composite coagulation [8].
Spray drying is commonly used [9], because the microencapsulated powder grease particles prepared by this method are small and uniform, have good uniformity and stability, the powder particles are more regular, more conducive to preservation, and at the same time, it has become the most commonly used method for preparing powder grease because of its advantages of short time and low cost.
Application in animal fats and fats
3.1 lanolin.
The saturated fatty acids in lanolin fat are higher than those of other animal fats, and it is rich in nutrition and flavor, but unprocessed lanolin is difficult to store for a long time and is easy to oxidize and deteriorate, so Wang Hao et al. [10] applied powdered oil technology to lanolin in order to improve the shortcomings of lanolin and the properties of oil substances, so as to improve storage stability.
The best wall material was screened out by emulsion stability, that is, the mass ratio of maltodextrin and -cyclodextrin was 4 1, 4% soybean protein isolate was selected as the protein wall material, the mass ratio of monoglyceride to sucrose ester was 1 4, and the mass ratio of wall material to core material was 4 1. The final sheep's tail oil powder is milky white in color, slightly oily, and can be quickly dissolved in hot water.
Fig.1 Effects of different indexes on emulsion stability and embedding efficiency.
3.2 butter.
Butter is popular among consumers in the Middle East because of its unique flavor and high nutritional value. In order to develop halal butter powder and grease products suitable for the Middle East and expand the international market.
Fan Tingting [6] used butter as the core material, yak sodium caseinate, maltodextrin, glucose syrup and gum as the main raw materials, and used microencapsulation technology to optimize the production process, and most of the particles had a complete and dense surface structure, no cracks, and uniform particle size, indicating that the embedding effect of the wall material on butter was better after spray drying.
Fig.2 Scanning electron microscope of powdered grease with different butter loading**.
The final butter powder had low moisture content, good solubility and preparation, low trans fatty acid content, and significantly improved storage stability. The reason is that the butter powder grease is protected by the wall material, and it is difficult for oxygen to penetrate into the dense wall structure, which effectively prevents the oxidation of the core material, thereby prolonging the shelf life of the product.
Fig.3 Comparison of POV values during storage.
3.3. Fish oil.
Fish oil is rich in polyunsaturated fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which play an important role in the prevention and treatment of cardiovascular diseases, improving eyesight, and strengthening the brain [11].
However, fish oil itself has a fishy smell, is insoluble in water, and is highly oxidative rancid. If fish oil is microencapsulated, it can not only isolate oxygen, light and heat in the environment, inhibit the oxidation of fish oil, prolong the shelf life, but also facilitate the use, transportation and storage of fish oil.
Huang Shanjun et al. [12] used low-viscosity octenylsuccinate starch ester (OSA S) and maltodextrin (MD) with good self-emulsification as compound wall materials, and prepared fish oil microcapsules by spray drying method, and obtained the best ones through optimization.
The preparation conditions of self-emulsifying fish oil microcapsules were as follows: OSA S and MD compound ratio 3 2, solid content 30%, core-wall ratio 1 3, homogenization pressure 30 MPa, and air inlet temperature 190.
Chen Q et al. [13] used spray drying and freeze-drying methods to prepare the performance and stability of fish oil microcapsules co-coated with phytosterol esters and limonene. The volatile components (p < 005) was significantly increased, and the surface oil content was significantly reduced, resulting in higher microencapsulation efficiency and significantly higher loss of limonene flavor in lyophilized samples. It shows that the powder produced by spray drying has better performance and better protection of the core material.
Chen Xiaowei [14] prepared a total oil content of 76. by spray drying technology after using natural soapskin saponin (QS) to self-assemble an emulsion with stable characteristics at the oil-water interface76% powdered fish oil, and finally concluded that the self-assembly characteristics of natural soapskin saponins at the oil-water interface will improve the embedding and oxidation properties of powdered fish oil, and provide good reconstitution properties and stability under extreme environmental conditions, which provides guidance for oil powdering.
Fig.4 Different concentrations of qs and 1Variation of peroxide value of 5% SC (traditional casein) to prepare powdered fish oil with induction time.
Summary
The microencapsulation technology can convert liquid oil into solid powder oil, and the wall material of microcapsule can protect the oil from the influence of external environmental factors such as oxygen, water, temperature, etc., isolate undesirable odors, improve the stability and shelf life of oil, improve food texture and flavor, and improve the bioavailability of functional factors.
The application of this technology to animal fats and fats has also broadened its range of applications. For the butter production industry, butter can not only be used in the production of hot pot bases, but also widely used in other food fields such as baked goods and solid beverages.
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