Shelf life and sensory attributes of a fruit smoothie-type beverage processed with moderate heat and pulsed electric fields

Smoothie-type beverages are usually preserved by mild pasteurisation (MP) but combining moderate heat (H) and pulsed electric fields (PEF) could represent an alternative technique achieving similar, or better, microbiological safety and shelf life, and possibly lowering the thermal impact on physical and sensory product properties. Following H (55 degrees C after 60 s) and PEF (34 kV/cm, 60 mu s) the microbiological shelf life of smoothie stored at 4 degrees C was extended over that of mildly pasteurised (72 degrees C, 15 s) smoothie (21 vs. 14 days (P < 0.05), respectively). Similar trends were obtained for both treatments regarding the shelf life stability of smoothie pH and conductivity (P >= 0.05). H/PEF-treated smoothie achieved better stability of Brix and viscosity than MP (P < 0.05) while better colour stability was obtained for the latter than for H/PEF-treated smoothie (P < 0.05). Sensory evaluation of untreated, MP-treated and H/PEF-treated smoothie indicated comparable overall acceptability of the products (P >= 0.05). Due to superior microbiological shelf stability and generally comparable attributes of the smoothie-type beverage H/PEF preservation proved to be a feasible processing alternative to fruit smoothie treatment with MP. (C) 2010 Elsevier Ltd. All rights reserved.