Application of innovative technologies, moderate-intensity pulsed electric fields and high-pressure thermal treatment, to preserve and/or improve the bioactive compounds content of pumpkin

The application of novel technologies such as moderate-intensity pulsed electricfields (MIPEF) and/or highpressure thermal (HPT) treatments improved the quality of processed pumpkin. MIPEF was applied to wholepumpkin in order to increase the bioactive compounds content, in contrast, HPT treatment was applied in orderto preserve the purées. Traditional thermal treatment (TT) of pasteurization and sterilization was compared withequivalent HPT treatments. The effect of processing (TT vs. HPT) in purées made from pumpkin pretreated withMIPEF was evaluated. Microbiological counts, enzyme inactivation (polyphenol oxidase, PPO) and bioactivecompounds content (carotenoids, phenolic compounds and antioxidant activity) were analyzed in all processedpurées. Regarding the pretreatment of the pumpkin, the application of MIPEF increased the content of somebioactive compounds of interest, such as carotenoids. The HPT treatment equivalent to sterilization preservedhigh levels of carotene compounds and antioxidant activity of pumpkin purée although this treatment im-portantly modified the original color of purée. However, the HPT treatment equivalent to pasteurization did notinactivate PPO enzyme in contrast to the effect reached by the equivalent TT. The bioactive compounds levels inHPT treated purée were similar or lower than those treated by TT.Industrial relevance:Pulsed electricfields and high pressure thermal processing are emerging non-thermal foodprocessing technologies. Moderate-intensity pulsed electricfields (MIPEF) were applied to increase the gen-eration of bioactive compounds in vegetables. This treatment enhanced the carotenoids content in pumpkin.High pressure thermal treatment (applied at conditions equivalent to sterilization) was the method that bestpreserved pumpkin purées. The application of MIPEF to pumpkin and HPT treatment to the resulting puréescould be proposed as a strategy for producing and preserving vegetable products with high bioactive compoundscontent.

The authors wish to acknowledge the financial support by the project INIA RTA2010-00079-C02. R. Ramírez thanks Extremadura Government for her grant (TA130125, DOE 22/07/2014).