How to Get Food Grade Beta Carotene Powder by Spray Drying Technology?

Beta-carotene is the most common carotenoid and the most widely used carotenoid, hereinafter referred to as carotene. Humans and many animals cannot synthesize carotene on their own, and carotene is the main source of vitamin A [1]. Carotene is broken down into two molecules of vitamin A in the human body. Vitamin A is essential for human growth, and can prevent disease and improve the body's immune system [2].

Carotene is very unstable and prone to degradation under the influence of light, oxygen and heat. The polyene system in its molecular structure makes the molecule extremely susceptible to degradation and isomerisation [3]. As pure carotene is crystalline, insoluble in water and slightly soluble in fats and oils [4], and is itself highly susceptible to oxidation, its use in beverages and other foods is greatly limited. When added to solid foods, the coloring effect is uneven, and in liquid foods it floats or settles. These limited solubility and high sensitivity to oxygen, as well as the difficulty of carotene in its crystalline form being broken down and absorbed in the human body, affect its bioavailability and also result in a great waste [5].

People have gradually shifted their research focus to the study of carotene dosage forms. In practical applications, carotene is generally formulated into different dosage forms, such as oil suspensions, water dispersible emulsions, and water dispersible dry powders, according to the characteristics of different foods, in order to meet the different processing needs of foods [6].

Spray drying refers to the process of spray drying tower, using the mechanical force of the atomizer to atomize the liquid into very fine droplets, the droplets come into contact with the drying medium hot air, after mass transfer and heat exchange [7], to obtain the dried carotene water dispersible dry powder.

This paper mainly studies the spray drying process of carotene water dispersible dry powder. Carotene water dispersible dry powder is a yellow to red or reddish brown, fine particle powder with good fluidity, which can be dispersed in cold water and produce a yellow to orange color. Carotene dispersible dry powder is made by evenly dispersing carotene in a matrix composed of gelatin, carbohydrates, etc., adding food-grade vitamin E and vitamin C as a complex antioxidant, and then forming the carotene into small microcapsules with a shell-like packaging material on the outside through a molding process. This isolates the carotene from air, light, oxygen, etc., greatly improving the stability of the product.

1. Index control during research

1.1 Quality control of carotene water dispersible dry powder

Carotene water dispersible dry powder can be evenly dispersed in water. It is widely used in hard capsules and tablets of health food, which is more convenient for packaging and transportation. It can be evenly dispersed in cold water, which is convenient for use in beverages and liquid foods. Since it is wrapped in a shell-like packaging material, it reduces contact with the outside world and has a longer shelf life. Therefore, the embedding technology of carotene dispersible dry powder is particularly important. The unique reticulated molecular structure of gelatin is used to effectively encapsulate the carotene molecules. Vitamin E and vitamin C are added as a complex antioxidant to effectively protect the carotene molecules. Filling ingredients such as sucrose are added to improve the flavor of the carotene dosage form. The product is packaged in automated aluminum-plastic packaging to ensure effective storage. The spray-drying microencapsulation technique is used to prepare the carotenoid water-dispersible dry powder, in which the high-purity carotenoids are completely encapsulated in a matrix of gelatin and carbohydrates with a complex antioxidant, forming a microcapsule structure with good dispersibility. It exists stably in the form of a microemulsion in an aqueous solution.

1.2 Energy-saving control of the preparation process for carotene water dispersible dry powder

In industrial production, energy conservation and environmental protection have always been research hotspots. By controlling the moisture content of the carotene water dispersible dry powder solution, the liquid is atomized through a high-speed rotating atomizer. Under the condition of high-speed rotation of the atomizer, the emulsion enters the atomizer chamber from the axis of the atomizer. The material generates centrifugal force F=mrω2 due to the rotation. When F<mrω2, the material moves in the direction away from the center of the circle and is thrown out of the ring by the atomizer through the small holes in the atomizer disc, forming small liquid droplets and atomizing the liquid.

Energy-saving measures are related to the shape of the atomizer disc, its rotational speed, the nature of the liquid and the feed rate. Generally, industrial atomizing discs are single-row circular, oval, rectangular, or M-shaped. By modifying the shape of the atomizing disc, a multi-row circular atomizing disc can be used, and the number of holes in the atomizing disc can be increased. The aperture can also be reduced while maintaining the same area through the disc, doubling the number of holes. This structure can maintain a small mist distance, and the corresponding tower diameter can be smaller, resulting in a more even atomization effect and a larger spray volume. The atomizer atomizes the liquid material by mechanical force.

Increasing the rotational speed is conducive to increasing the cutting speed of the atomizing disc and also increases the feed rate. Reducing the moisture in the liquid material and lowering the viscosity, controlling the moisture in the preparation of the liquid material, as the viscosity is related to the moisture content, too low moisture content will lead to high viscosity of the liquid material. By seeking the appropriate moisture content, it is conducive to atomizing the liquid material and also increases the feed rate, thereby increasing the output. The purpose of atomizer modification is to achieve better atomization. The smaller the droplet size, the larger the specific surface area, and the larger the contact area with the hot air and the area for moisture evaporation, which is conducive to drying the material and increasing the output, improving thermal efficiency, and thus achieving energy-saving control.

1.3 Safety monitoring of the preparation process of carotene water-dispersible dry powder

The carotene water dispersible dry powder contains a large amount of carbohydrates, and the dust cloud concentration in the drying tower is within the explosion limit. In order to ensure safe production, a low-temperature spray process is used. The inlet air temperature is controlled to be less than 150 ℃, and the inlet air is treated at the same time. The air temperature is raised, the relative humidity of the air is further reduced, and the mass transfer rate of the air is greatly increased, thereby increasing the feed rate and reducing the inlet air temperature, which is conducive to maintaining the drying tower operating at a relatively low temperature and maintaining the safety of the drying tower. Through effective control of the spray drying process, the molecular structure of the prepared carotene water dispersible dry powder is closer to that of naturally occurring carotene, ensuring that it is more easily absorbed by the body in the final product.

1.4 Prospects for the industrial production of carotene water dispersible dry powder

Carotene effectively quenches singlet oxygen and triplet oxygen, inactivating free radicals. The well-known antioxidant vitamin E has a quenching rate constant of 0.3 for singlet oxygen, while carotene is 14, making it a high-quality antioxidant. Beta-carotene can enhance the body's disease resistance and reproductive capacity, effectively absorb ultraviolet rays, greatly reduce the incidence of skin cancer, and effectively reduce the incidence of this type of ultraviolet-induced skin cancer, so it is approved for use in sunscreen products. The biological functions of beta-carotene are increasingly being valued, and the prospects for its industrial production are also growing.

2 Conclusion

Spray drying technology for carotenoids is still developing, and it is an energy-efficient, safe and hygienic production method that is being used more and more widely in the food and pharmaceutical industries. The special physicochemical properties of carotenoids mean that spray drying technology for food-grade β-carotene is still being improved. Future research will focus on high-content, high-quality food-grade β-carotene spray-dried powders, as well as the formulation of these powders. This paper combines the current status of spray drying theory and the progress of technical applications, summarizes the spray drying experience in production over the past few years and the key points of improving spray dryer equipment, and serves as a reference for future improvements and production.

References

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