Schilling Susanne, Schmid Sandra, Jäger Henry, Ludwig Michael, Dietrich Helmut, Toepfl Stefan, Knorr Dietrich, Neidhart Sybille, Schieber Andreas, Carle Reinhold
Institute of Food Science and Biotechnology, Chair of Plant Foodstuff Technology, Hohenheim University, August-von-Hartmann-Strasse 3, 70599 Stuttgart, Germany.
J Agric Food Chem. 2008 Jun 25;56(12):4545-54. doi: 10.1021/jf0732713. Epub 2008 May 22.
As an alternative to thermal pasteurization, pulsed electric fields (PEF) were applied to apple juices on laboratory and pilot plant scale, investigating the effects on juice quality. PEF application still falls under the EU Novel Food Regulation. Consequently, extensive investigation of quality parameters is a prerequisite to prove substantial equivalence of juices resulting from the novel process and conventional production, respectively. Juice composition was not affected by PEF treatment. However, browning of the juices provided evidence of residual enzyme activities. On laboratory scale, complete deactivation of peroxidase (POD) and polyphenoloxidase (PPO) was achieved when PEF treatment and preheating of the juices to 60 degrees C were combined. Under these conditions, a synergistic effect of heat and PEF was observed. On pilot plant scale, maximum PPO deactivation of 48% was achieved when the juices were preheated to 40 degrees C and PEF-treated at 30 kV/cm (100 kJ/kg). Thus, minimally processed juices resulted from PEF processing, when applied without additional conventional thermal preservation. Since this product type was characterized by residual native enzyme activities and nondetectable levels of 5-hydroxymethylfurfural, also when preheating up to 40 degrees C was included, it ranged between fresh and pasteurized juices regarding consumers' expectation of freshness and shelf life. Consistent with comparable iron contents among all juice samples, no electrode corrosion was observed under the PEF conditions applied.
作为热巴氏杀菌的替代方法，在实验室和中试规模上对苹果汁施加脉冲电场（PEF），研究其对果汁品质的影响。PEF应用仍属于欧盟新型食品法规的范畴。因此，广泛研究质量参数是证明新工艺生产的果汁与传统生产的果汁在实质等同性的前提条件。果汁成分不受PEF处理的影响。然而，果汁的褐变证明了残留的酶活性。在实验室规模下，当将PEF处理与将果汁预热至60摄氏度相结合时，过氧化物酶（POD）和多酚氧化酶（PPO）可实现完全失活。在这些条件下，观察到了热和PEF的协同效应。在中试规模下，当将果汁预热至40摄氏度并在30 kV/cm（100 kJ/kg）下进行PEF处理时，PPO的最大失活率达到48%。因此，在不进行额外传统热保鲜的情况下应用PEF处理可得到最低限度加工的果汁。由于这种产品类型的特点是残留天然酶活性且5-羟甲基糠醛含量不可检测，即使包括预热至40摄氏度的情况，就消费者对新鲜度和保质期的期望而言，它介于新鲜果汁和巴氏杀菌果汁之间。与所有果汁样品中铁含量相当一致，在所应用的PEF条件下未观察到电极腐蚀现象。
