Ascorbic acid in orange juice-milk beverage treated by high intensity pulsed electric fields and its stability during storage

The degradation of ascorbic acid was determined in a ready-to-drink orange juice-milk beverage treated by high intensity pulsed electric fields (PEF). The effects of PEF treatment were compared to those of heat pasteurization (90 degrees C, 20 s). Four electric field strengths (15, 25, 35, 40 kV/cm) and six treatment times for each field (from 40 mu s to 700 mu s) were studied. Ascorbic acid degradation was adjusted to an exponential model. The obtained ascorbic acid degradation rate constants (k(E)) were -0.11.10(-3) +/- 0.03.10(-3) mu s(-1), -0.23.10(-3) +/- 0.07.10(-3) mu s(-1), -0.42.10(-3) +/- 0.09.10(-3) mu s(-1) and -0.60-10(-3) +/- 0.06.10(-3) mu s(-1) for field strengths of 15, 25, 35 and 40 kV/cm, respectively. For the shelf-life study a 25 kV/cm at 280 mu s treatment was applied and the beverages were stored at 4 and 10 degrees C. The ascorbic acid degradation rate during storage was adjusted to zero-order kinetics showing that beverages stored at 4 degrees C had better ascorbic acid retention than beverages stored at 10 degrees C. No significant differences were found between heat pasteurization and PEF treatments during storage. Industrial relevance: Food beverages are mainly preserved and made available to the consumer by different thermal treatments which involve a destruction of desirable food constituents such as nutrients, bioactive compounds, colour, flavour and texture. The present work demonstrates that the ascorbic acid degradation in an orange juice-milk beverage treated by pulsed electric fields was adjusted to zero-order kinetics and degradation rate during storage was adjusted to first-order kinetics. The shelf life of the orange juice-milk beverages is similar so much for the pasteurized beverages as for the treated by PEF. (C) 2009 Elsevier Ltd. All rights reserved.