Scaling up and process optimisation

After establishing LIFE microTAN enzymatic process at laboratory, it has been scaled up and a demonstration plant has been designed, constructed and set up.

Both pre-treatment and extraction conditions highly affect gelatine properties and, therefore, its end use. For this reason, during the scaling up of LIFE microTAN process, both the pre-treatment and extraction stages have been optimised in order to produce gelatine with suitable properties for microencapsulation applications.

scaling up

With this aim, and based on the results obtained at laboratory scale, a design of experiments (DOE) for the pre-treatment phase has been performed at medium-size scale and results have been statistically analysed. It consisted in a 2-level full design for 3 factors: temperature, time and protease concentration. In those studies, the effect of the processing parameters on both yield and gelling properties (the latter measured as Bloom value, according to ISO 9665) has been assessed.

Results have been statistically analysed by both factorial design and ANOVA. Main conclusions are summarised in the following table:

Factor/Interaction Yield Bloom
Significant Ranking1 Effect2 Significant Ranking1 Effect2
Temperature Yes 1 (-) No - n.a.
Time Yes 2 (+) No - n.a.
Concentration No - n.a. Yes 1 (-)
Temperature*Time Yes 3 (-)*(-)/(+) No - n.a.
Temperature*Concentration Yes 4 (-)*(+) No - n.a.
Time*Concentration No - n.a. Yes 2 (+)*(-)
Temperature*Time*Concentration No - n.a. Yes 3 n.p.

1 Ranking of relative significance of factors (1: highest significance). Only factors or interactions statistically significant have been included.
2 A positive effect indicates that the high level of the factor gives a hihger response. A negative effect indicates taht the low lwvevl of the factor gives a higher response.
n.a. Not applicable.
n.p. Not predictable.

This analysis has allowed selecting the most convenient process conditions. This information has been taken into account during the demonstration plant construction.

Results obtained in the medium-size scale were promising. In the project proposal, it was foreseen that at least 80% of collagen would be recovered as gelatine. According to the results obtained in the DOE, when the pre-treatment reaction is carried out under the selected conditions, a 75-80% of the dry waste (representing about 90% of native collagen in the waste) is transformed into gelatine with Bloom values of about 220 that had prove to be adequate for microencapsulation applications.

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