Optimization of pulsed electric field assisted extraction of bioactive compounds from blackcurrant

MAITE GAGNETEN; GRACIELA LEIVA; DANIELA SALVATORI; CAROLINA SCHEBOR; NAHUEL OLAIZ

Ljubljana

Congreso; ELECTROPORATION-BASED TECHNOLOGIES AND TREATMENTS; 2018

INTRODUCTIONIn the last decades an increasing interest in natural foodswith high antioxidant activity has been observed worldwide.Blackcurrant is a berry grown in Argentinian Patagoniawhich is recognized for being a very rich source ofbioactive compounds, such as anthocyanins and otherpolyphenols, with inmunomodulatory, antiinflamatory andanticancer properties [1]. However, these components arevery difficult to extract from the fruit matrix. For thispurpose, pulsed electric field technology offers a ?green?,economically viable, and nonthermal solution to assist theextraction process without destroying the bioactivecompounds.The objective of this work was to optimize pulsedelectric field (PEF) pre-treatment to enhance the extractionof bioactive compounds from blackcurrant by cold pressing.MATERIAL AND METHODSIQF blackcurrants (Ribes nigrum, Titania cultivar) werethawed under controlled conditions. For PEF treatment acustom electroporation chamber was constructed, consistingof an acrylic cuvette with two confronted rows of 22needles each, separated by 80mm.Response surface methodology was used to determinethe optimal PEF conditions using the desirability approach.The independent variables analysed were the electric fieldintensity (0 to 1950 V/cm, determined by a high-voltageprobe (100x)) and the number of pulses (of constantduration; 50 to 500 pulses). The effect of these parametersover the total polyphenolic content (TPC) (Folin?Ciocalteumethod [2]) and the antioxidant activity (AA) (bleachingmethod of radical cation (ABTS+.) [3]) was studied withthe objective of maximizing both responses. A factorialdesign of 4x3 levels was used and a complete replicate ofthe whole design was conducted. Statgraphics CenturionXVI.I software was used for response optimization.RESULTS AND DISCUSSIONBoth the electric field intensity and the number of pulsesshowed a positive effect over the response variables though,the first one was more influencing than the latter one. TheAA increased when the electric field increased up to 1300V/cm but a further increase to 1950 V/cm caused a decreaseof the response (Figure 1). Other authors have reported thathigh levels of energy may cause degradation of bioactivecompounds in food [4].The response surface is shown in Figure 2. Thedesirability function reached a maximum value of 0.804,indicating that a good maximization for both responses wasachieved. The optimal treatment conditions determined bythe system were an electric field of 1256 V/cm and 319pulses which would result in TPC and AA values of 3.8 and1.8 mg GA/g. The predicting model was tested applying theoptimal treatment to a new set of samples reaching averagevalues of 3.8 ± 0.2 and 1.88 ± 0.06 mg GA/g for TPC y AArespectively.ACKNOLEDGEMENTSThe authors acknowledge the financial support from theSlovenia-Argentina bilateral project.REFERENCES[1] Gopalan, A., Reuben, S. C., Ahmed, S., Darvesh, A.S., Hohmann, J. & Bishayee, A. (2012). ?The healthbenefits of blackcurrants?. Food & Function, 3, 795.[2] Archaina, D., Leiva, G., Salvatori, D. & Schebor, C.(2018). ?Physical and functional properties of spray-driedpowders from blackcurrant juice and extracts obtained fromthe waste of juice processing?. Food Science andTechnology International, 24(1). [3] Cayupán C., Ochoa Y. S. & Nazareno M. J. (2011).?Health-promoting substances and antioxidant properties ofOpuntia sp. fruits. Changes in bioactive-compound contentsduring ripening process?. Food Chemstry, 126(2), 514?519.[4] Bobinaitė, R., Pataro, G., Lamanauskas, N.,?atkauskas, S., Vi?kelis, P., & Ferrari, G. (2015).?Application of pulsed electric field in the production ofjuice and extraction of bioactive compounds from blueberryfruits and their by-products?. Journal of Food Science andTechnology, 52(9), 5898?5905.