Comparing the impact of high pressure, pulsed electric field and thermal treatments on the quality attributes of raspberry juice

Abstract

Raspberry juice is a nutrient-rich beverage valued for its high concentrations of anthocyanins, vitamin C, and volatile aroma compounds, which contribute to its health benefits and sensory appeal. However, processing methods can significantly impact these quality attributes. This study compared the effects of thermal pasteurization (TT), high-pressure processing (HPP), and pulsed electric fields (PEF), each at two intensity levels, on the physico-chemical and sensory properties of raspberry juice. Evaluated parameters included colour, viscosity, turbidity, browning index (BI), anthocyanin stability, ascorbic acid retention, and volatile aroma compounds. Thermal treatments caused significant colour changes, accelerating browning reactions and degrading anthocyanins and floral aroma compounds. Higher thermal treatment (80 °C) resulted in the most pronounced browning and colour loss, reducing sensory quality. HPP treatments demonstrated pressure-dependent effects, with low-intensity HPP treatment causing the highest BI due to enzyme activation, while high-intensity HPP moderated browning. HPP also reduced viscosity and turbidity likely due to pectin degradation. In contrast, PEF-treated samples exhibited minimal changes in colour and browning but retained the lowest ascorbic acid levels, likely due to temperature spikes during processing. Multifactorial analysis identified volatile aroma compounds, particularly α-ionone and β-ionone, along with viscosity, turbidity, and BI, as the key differentiating factors among treatments. Particularly, ascorbic acid was not a primary contributor to the model, highlighting its limited role in treatment differentiation. The findings suggest that high-intensity PEF treatment offers the appropriate balance between nutrient retention and sensory quality, while TT and HPP treatments require optimization to minimize quality losses.