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 electric fields (MIPEF) and/or high pressure thermal (HPT) treatments improved the quality of processed pumpkin. MIPEF was applied to whole pumpkin in order to increase the bioactive compounds content, in contrast, HPT treatment was applied in order to preserve the purees. Traditional thermal treatment (TT) of pasteurization and sterilization was compared with equivalent HPT treatments. The effect of processing (TT vs. HPT) in purees made from pumpkin pretreated with MIPEF was evaluated. Microbiological counts, enzyme inactivation (polyphenol oxidase, PPO) and bioactive compounds content (carotenoids, phenolic compounds and antioxidant activity) were analyzed in all processed purees. Regarding the pretreatment of the pumpkin, the application of MIPEF increased the content of some bioactive compounds of interest, such as carotenoids. The HPT treatment equivalent to sterilization preserved high levels of carotene compounds and antioxidant activity of pumpkin puree although this treatment importantly modified the original color of puree. However, the HPT treatment equivalent to pasteurization did not inactivate PPO enzyme in contrast to the effect reached by the equivalent TT. The bioactive compounds levels in HPT treated puree were similar or lower than those treated by TT. Industrial relevance: Pulsed electric fields and high pressure thermal processing are emerging non-thermal food processing technologies. Moderate-intensity pulsed electric fields (MIPEF) were applied to increase the generation 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 best preserved pumpkin purees. The application of MIPEF to pumpkin and HPT treatment to the resulting purees could be proposed as a strategy for producing and preserving vegetable products with high bioactive compounds content.