Milk-Clotting Properties and Primary Proteolysis of a Lyophilised Extract from Artichoke Flowers (Cynara scolymus L.)

Research background: A few studies have investigated Cynara scolymus enzymes as a substitute for calf rennet in cheese making. They used aqueous extracts prepared by maceration of plant material and stored by freezing. However, it was indicated that lyophilisation is a better alternative to preserve the coagulant properties of plant extracts over a longer period of time, as it is a more controllable, stable and hygienic alternative with a better shelf life that is easier to transport, store and standardise. Experimental approach. We obtained a lyophilised extract of mature artichoke flowers, named CS, which was characterised for its milk-clotting properties at different pH and temperatures. In addition, the potential yield, whey composition and the primary hydrolysis profile of caseins by urea-polyacrylamide gel electrophoresis (PAGE) of mini curds prepared with different doses of coagulant were determined. Results and conclusions: The lyophilised extract was able to hydrolyse casein and showed stable proteolytic activity at pH=6.4 and 37 °C for 50 min, which decreased when the process temperature was increased to 41 and 45 °C and was lost at 70 °C. On the other hand, milk-clotting activity increased significantly (p<0.001) when the temperature increased from 37 to 45 °C and the pH of the milk decreased from 6.8 to 5.8. Potential yield between 10 and 17 % was obtained for the mini curds prepared with the lyophilised artichoke extract, and the casein degradation pattern obtained by urea-PAGE was similar to that of the commercial coagulant. Novelty and scientific contribution: On a laboratory scale, our work has shown that the lyophilised artichoke extract has sufficient proteolytic and coagulant activity to be used as a milk coagulant, i.e. plant rennet, in cheese making as an alternative to animal rennet. As this extract is lyophilised, it has the advantage of being a better alternative in terms of preservation and shelf-life. It offers an innovative way to diversify cheese products and appeal to consumers with different dietary preferences and needs.Antecedentes de la investigación. Algunos estudios han investigado las enzimas Cynara scolymus como sustituto del cuajo de ternera en la elaboración de queso. Utilizaron extractos acuosos preparados mediante maceración de material vegetal y almacenados mediante congelación. Sin embargo, se indicó que la liofilización es una mejor alternativa para preservar las propiedades coagulantes de los extractos de plantas durante un período más largo de tiempo, ya que es una alternativa más controlable, estable e higiénica con una mejor vida útil y más fácil de transportar, almacenar y estandarizar. Enfoque experimental. Obtuvimos un extracto liofilizado de flores maduras de alcachofa, denominado CS, que se caracterizó por sus propiedades coagulantes de la leche a diferentes pH y temperaturas. Además, se determinó el rendimiento potencial, la composición del suero y el perfil de hidrólisis primaria de caseínas mediante electroforesis en gel de urea-poliacrilamida (PAGE) de mini cuajadas preparadas con diferentes dosis de coagulante. Resultados y conclusiones. El extracto liofilizado fue capaz de hidrolizar la caseína y mostró actividad proteolítica estable a pH=6,4 y 37 °C durante 50 min, la cual disminuyó cuando la temperatura del proceso se incrementó a 41 y 45 °C y se perdió a 70 °C. En el otro Por otro lado, la actividad de coagulación de la leche aumentó significativamente (p