Morphology and strength of cellulose derivatives coatings in fluid bed processing

Microencapsulation is defined as a process in which small particles or droplets are surrounded by a coating in order to obtain small capsules with many valuable properties. One of the most commonly used and most promising techniques to realise microencapsulation in the food industry is fluidized bed coating. The effectiveness of the fluidized bed coating process can be verified by the quantification of the coating quality. Verification of coating quality is an important issue for companies that produce encapsulated food ingredients since deviations from the intended value of coating thickness may cause problems related to release of core material. The main goal of this PhD study was to examine the quality of coatings obtained from four selected water-soluble cellulose derivatives: methylcellulose, low and high viscous type of carboxymethylcellulose and hydroxypropylcellulose. The quality of the coatings was examined for two aspects: coating morphology and coating strength. To this end, the Confocal Laser Scanning Microscopy (CLSM) was used to determine the coating morphology and the repeated impact tests (RIT) were applied to evaluate the attrition strength of cellulose derivative coatings on various core materials. Within this PhD research, coating quality and coating thickness of selected materials were quantified. Furthermore, the relationship between coating material properties and the coating quality was examined

Effect of food processing of pearl millet (Pennisetum glaucum) IKMP-5 on the level of phenolics, phytate, iron and zinc

Pearl millet is consumed as a staple food in semi-arid tropical regions. With a view to upgrading the micronutrient status of pearl millet-based foods, the effects of single operations and of porridge preparation scenarios on levels and in vitro solubility (IVS) of iron and zinc and mineral complexing factors (phytates: inositol phosphates and phenolic compounds) were tested. Disc milling of grain may add significant iron but this is not necessarily IVS iron. Soaking of grains results in a 25% loss of iron, but also facilitates endogenous phytate degradation, particularly when combined with milling and cooking. Germination and lactic acid fermentation both result in partial phytate degradation. Cooking does not decompose phytates, but results in complex formation of phenolic compounds as measured by a significant reduction in reactive hydroxyl groups. Because of its different distribution in the grain, zinc is generally less affected than iron. Phytate reduction by endogenous phytases is inhibited at low pH as caused by fermentation. Kanwa (alkaline rock salt) could be a functional cooking ingredient as a source of minerals and to react with phenolic substances. The relative IVS of iron was doubled by germination of grain and increased 3-fold by fermentation of wholemeal slurry. Zinc IVS tended to increase on cooking with kanwa, but decreased in cooked fermented flou

Etude experimentale des configurations bruyantes

SIGLECNRS-CDST / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Water soluble cellulose derivatives as coating agents in fluidized bed processing

The quality of a particle coating is strongly affected by both the parameters of the fluidized bed process and the properties of coating materials. Within this research, the effect of solution properties (viscosity of the coating solution, coating solution droplet size) on the quality of coatings obtained from three water-soluble cellulose derivatives (methylcellulose, carboxymethylcellulose, and hydroxypropylcellulose) was investigated. Coating quality was quantified using confocal laser scanning microscopy (CLSM). The results showed a pronounced effect of viscosity on the quality of methylcellulose and carboxymethylcellulose coatings. The best results for methylcellulose coatings were obtained when the least concentrated and at the same time least viscous solution was sprayed onto the fluidized particles. In the case of carboxymethylcellulose the best results were obtained using an intermediate (5w/v %) concentrated coating solution. The quality of the hydroxypropylcellulose coatings was not influenced by the coating solution viscosity and presented very similar values after performing all fluid bed experiments. For the materials covered in this work, the best coating quality was obtained for hydroxypropylcellulose. The least uniform coatings with the highest number of coating deficiencies and highest degree of agglomeration of coated beads were found for carboxymethylcellulose