Microbial and Enzymatic Changes in Fruit Juice Induced by High-Intensity Pulsed Electric Fields

Abstract

High-intensity pulsed electric fields (HIPEF) treatment is a nonthermal technology that has been studied in the last few years as an alternative to heat treatments. It consists of applying pulses of high electric field (kV/cm) during a short time (μsec or msec) at low or moderate temperature.

Because of their properties, fruit juices are appropriate products to be processed by HIPEF. Studies on the effects of HIPEF on microorganisms show that this treatment destroys microorganisms at levels of heat pasteurization with lower destruction of vitamins, flavor compounds, and other micronutrients. The majority of enzymes that are responsible for adverse biological reactions in fruit juices are inactivated by HIPEF. The effects of HIPEF, as for thermal treatments, are mainly described by first-order models. Furthermore, others models are also proposed to fit some effects of HIPEF on the enzymatic activity or microorganisms population. Fewer works are focused on the effects on organoleptic, physical, and chemical properties of fruit juices, but results show that most of the properties remain unchangeable. The changes, if they occurred after a HIPEF treatment, are always less important than those produced by heat.

Keywords:

• High-intensity pulsed electric fields
• Fruit juices
• Microorganisms
• Enzymes

Acknowledgments

The authors thank the Interministerial Commision for Science and Technology (CICYT) of Spain for its support of the work included in projects ALI 99-1228 and AGL 2002-04399-C02-02 ALI. Moreover, Alexandre Espachs thanks the Departament de Universitat, Recerca i Societat de la Informació of the Generalitat de Catalunya for the predoctoral grant.