Production of bioavailable preparations

Colouration of hydrophilic media - Production of bioavailable preparations 

The industrially produced carotenoids are virtually insoluble in aqueous media. It was therefore a great challenge to develop water-dispersible preparations for the food and feed sector. As has been shown by application tests and animal experiments, sufficient colouring intensity and maximum bioavailability can be achieved by reducing the particle size to less than 0,5 xm. Fig. 2 shows the effect of particle size on the UVA is absorption spectrum of (3,P-carotene (3) in water [95]. The structure and size of particles in the submicrometre range are studied by electron microscopy, dynamic light scattering, microelectrophoresis and UVA is spectroscopy. 

The individual formulation methods differ in the measures used for micronizing the carotenoid crystals produced by synthesis. In a process developed by Danochemo [96], the crystals are reduced in size in aqueous media by mechanical means to give mean particle sizes of 0.4 pm, by grinding in the presence of a hydrocolloid to prevent reaggregation. Bioavailability is further improved by briefly heating this suspension to approximately 180°C, which causes the particles of the microcrystalline active compound to become substantially amorphous. Prior to further processing, an aqueous matrix solution is added to the carotenoid suspension. 

1)ballmill 2) pressure pump 3) heat exchanger 4) relief valve 5) tank 6) spray dryer 7) mixer 8) homogenizer 9) dissolution chamber 10) evaporator. MS = matrix solution. 

The matrix solution contains a protective colloid, usually gelatin, which is adsorbed in a thin layer on the surface of the carotenoid particles which are thus made hydrophilic and can form stable dispersions in water at suitable pH. Depending on the nature of the further processing, the matrix solution also contains additives, for example natural antioxidants such as tocopherol and ascorbic acid, emulsifiers such as lecithin and ascorbyl palmitate, and sugar and starch to improve the mechanical properties of the end products. 

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