Rheological property modification and microbial inactivation of hawthorn jam under ultra-high-voltage electrostatic field

Abstract

Ultra-high-voltage electrostatic field sterilisation (UVEFS) is an emerging technology for the non-thermal modification and microbial inactivation of soft food materials. However, the effect of UVEFS on soft food materials remains unclear. In this study, hawthorn jam, a type of soft food material, was subjected to continuous UVEFS at 60 kV and a flow rate of 5 g/min to assess its rheological properties, microbial inactivation, and quality attributes in comparison with those of hawthorn jam treated with water bath, microwave, radio frequency. The UVEFS-treated hawthorn jam displayed higher viscoelasticity (G' = 1902 Pa, G" = 718 Pa), rheological properties (K = 310 Pa·sⁿ), gel strength (20.84 g*cm), and water-binding capacity than the jams treated using other methods. Furthermore, the UVEFS group demonstrated a microbial lethality rate of over 90 %, with the population of moulds and yeasts were reduced by 1.78 log CFU/mL, and its nutrient contents were better maintained. Unlike the jams subjected to other thermal treatments, which showed a decrease in total phenolic content (TPC), hawthorn jam treated by UVEFS demonstrated a 2 % increase in TPC. The pectin content of the UVEFS-treated jam was basically identical to that of the non-treated sample, and improvements in flavor and colour were observed (ΔE = 1.32). Overall, the rheological and quality properties of the hawthorn jam prepared by UVEFS were significantly better than those of hawthorn jam prepared by other thermal treatment methods. Therefore, as a new non-thermal processing technology for soft food materials, UVEFS has potential application value in the processing and storage of uniform and viscous soft food materials such as fruit and vegetable jams and pastes.

Industrial relevance

Soft foods are thermally treated to achieve sterilisation. However, this process can affect the gel properties and quality of food. In this study, we developed a novel non-thermal sterilisation technology using ultra-high-pressure electrostatic fields. Food treated using this technology showed improvements in gel properties and better quality than food subjected to thermal treatment. Therefore, as a new non-thermal processing technology for soft food materials, UVEFS has potential application value in the processing and storage of uniform and viscous soft food materials such as fruit and vegetable jams and pastes.