ID: 2283

  • Title:
    A new generation of extracts obtained from cardoon flowers (Cynara cardunculus L.) using Pulsed Electric Fields

    Barracosa, Paulo -  Escola Superior Agrária de Viseu, Instituto Politécnico de Viseu, Quinta da Alagoa, 3500-606 Viseu, Portugal; Centro de Investigação CERNAS-IPV, Instituto Politécnico de Viseu, Campus Politécnico, Repeses, 3504-510 Viseu, Portugal
    Aguiar, Mafalda Energy Pulse System
    Oliveira, Jorge - ESAV; Cernas
    Pinto, António - ESAV; Cernas
    Coutinho, Rui - ESAV
    Gaião, Davide - ESAV
    Antunes, Manuela - Cynatura
    Redondo, Luis - Instituto Superior de Engenharia de Lisboa

    A new generation of extracts obtained from cardoon flowers (Cynara cardunculus L.) using Pulsed Electric Fields

    Cardoon flower (Cynara cardunculus L.) is a mandatory ingredient for the coagulation of a set of PDO cheeses whose coagulant action results from the specific biochemical activity of cardosins over the milk caseins. For the success of the PEF technology, it is essential to know the morphology and ultrastructure of the cardoon flower with the respective locations of the cardosins and the size of the cells and organelles. CYNEXT involves the production of a new generation of extracts with a standardized biochemical formulation obtained from cardoon flower for application in the coagulation process of sheep cheese with PDO. The extracts were produced from frozen cardoon flowers subjected to the application of distinct treatments of Pulsed Electric Fields (PEF). The use of frozen flowers was an innovative procedure that can optimize the extraction. The extracts were evaluated by biochemical markers to respond in a very specific way to guarantee cheeses with a brand of identity and exclusivity.

    For each treatment, including the control, 20 g cardoon flowers were added to 200 mL of water. Four PEF treatments (A-D) with distinct number of pulses and specific energy were performed, each with three replications. Treatment A (1kV/cm, 1.8kJ/kg, 20 μs, 10Hz, 60 pulses). The other three treatments (B-D) used the same electrical field strength and distinct number of pulses: (B) ; 2kV/cm, 2.4kJ/kg, 20 μs, 10Hz, 20 pulses (C) 2kV/cm, 3.6kJ/kg, 20 μs, 10Hz, 30 pulses ; and (D) 2kV/cm, 7.6kJ/kg, 20 μs, 10Hz, 60 pulses. There was a control treatment without PEF application.

    During the assay, the parameters pH, conductivity, turbidity, protein concentration and absorbance at 230, 260, 280 and 320 nm were evaluated before PEF application (T0) and after PEF [1h (T1), 2h (T2), 4h (T3), 12h (T4), 24h (T5) and 48h (T6)]. The samples collected at distinct times and treatments were analysed by electrophoresis using a native PAGE system (Bio-rad Miniprotean II).

    The data were analyzed through one-way Analysis of Variance (ANOVA) to test the effects of treatments and time, independently, in the dependent variables, and post hoc Tukey Honestly Significant Difference tests to compare the means. IBM SPSS v29 software was used, with a significance level of 0.05.

    The pH value, in average, started at 6.0 and after 48 h attained 4.9. The control obtained the highest pH compared with all other PEF treatments (p<0.05). The lowest pH is related with higher elution of cardosins which are acidic proteinases.

    The conductivity at time T0, 30 min after the addition of the flowers, in average, started at 1.4 μS cm-1. After the PEF assay, the control showed the lowest increase. After 4 h the turbidity increases 49.5% in treatment A and 20.0% in the control.

    The turbidity, in average, started at 100 NTU. After application of PEF, the treatment B increase 87.2%, followed by the treatments A, C and D with 50-55% compared with 5% of control. These values were maintained for 4 hours. The protein concentration, 4 hours after PEF, showed an increase to a double concentration for all treatments (A-D) compared with control (p<0.05). The absorbances at 230 nm, 260 nm and 280 nm showed the same pattern.

    The PEF, independently of the treatment (A-D) increase the extraction of cardosins using all parameters compared with the control. Based on turbidity, the treatment A showed the highest increase. All the other parameters showed not statistically differences between the PEF treatments. Further studies are necessary to confirm these previous results and evaluate the extract stability related with biochemical composition and microbiology for cheese production.

    Cardoon; PDO Cheese; Cardosins

    Acknowledgments The authors acknowledge to the INOVC+/IPV program and BCheeSE project (PRR-C05-i03-I-000168). Furthermore, we would like to thank the CERNAS Research Centre and the Polytechnic Institute of Viseu for their support.

    Topic 1:
    10. Food safety and food preservation

    Topic 2:
    11. Agricultural crops and farming

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