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International audience; A surface response experimental design was used to quantify the effects of the final cooling temperature and the residence time at this temperature on the filtration characteristics of the crystal suspension and the quality of the fractions during chicken fat dry fractionation. The crystal morphology was monitored to gain insight into the observed effects. Temperature affected crystallization and the characteristics of the olein and stearin fractions. The crystals became fragmented as the residence time increased, thus leading to a decrease in the filterability of the crystal suspension and an increase in the proportion of the entrained liquid phase. The residence time only affected the quality of the stearin fraction. This time effect was noted at high cooling temperatures in the investigated experimental domain. At low temperatures, increasing the residence time enhanced crystal growth and increased the extent of unsaturation of both fractions without modifying the filtration features. (Résumé d'auteur)

The impacts of the cooling program on crystal morphology, crystal suspension filtration properties and the characteristics of fractions resulting from chicken fat dry fractionation were assessed. The quality of the fractions was found to depend on the nature of the crystallized material and was also closely related to the filtration properties of the crystal suspension, which in turn were controlled by the cooling conditions. A slow cooling rate during the nucleation step was necessary to enhance process selectivity, and this rate could be accelerated once the first crystals had formed. These findings enhanced our understanding of the mechanisms involved during dry fractionation and highlighted the efficacy of a three-phase cooling program, including (1) cooling from 70 to 26°C, (2) slowdown in the cooling rate, and (3) a second rapid cooling down to the final temperature at which the fat is held for a specified time. (Resume d'auteur)

Chicken fat was processed by dry fractionation to obtain a solid fraction at ambient temperature. Crystallisation and separation were performed using industrial-type procedures. Crystal formation and changes were monitored, while determining the composition, physical characteristics and thermal behaviour of the initial fat and resulting fractions. Dry fractionation, under the described conditions, produced stearin that resembled other animal fats such as lard and tallow and with better physical features than the initial fat stock. The results of this study also highlighted the mechanisms involved during the dry fractionation process.