Impact of salt and sugar reformulation on processing parameters for orange juice and tomatoes using ohmic heating

The purpose of this paper is twofold: first, it aims to investigate how salt and sugar reduction in foods due to the pressure from the emerging food regulations will affect the physico-electrical properties (PEPs) of orange juice and tomatoes during a selected PEP-dependent thermal processing. Second, the authors are keen to understand how variations in salt and sugar ingredients will affect the time-temperature processing requirements.

PEPs of the samples (orange juice and tomatoes) were measured using the KD2 thermal analyser and RS conductivity metre. Both samples with varying salt and sugar levels were subjected to ohmic heating processing using a 10 kW ohmic heater. Dehydration rates and processing times for pasteurisation were obtained.

Electrical conductivity increases with added salt in tomato puree but decreases with added sugar in orange juice. Statistical evidence confirmed significant changes in heating rates and processing times of tomatoes and orange juice as their relevant salt and sugar levels change. Reduction in salt content in tomato puree led to increase in time and energy for the thermal processes. While reduction in added sugar in orange juice results led to reduction in processing time and energy requirement for the processing operation.

The study is limited to small change in salt and sugar variations in order to reflect recommended limits. There were therefore no significant changes in thermal conductivity for the range investigated. Also this study is focussed on two food products.

Current pressure on the need to reduce salt and sugar in foods necessitates research to increase food processing industry insight into the process and product impacts of such recipe changes, with particular regard to processing efficiency and product safety and quality.

This study represents an attempt to understand the impact of salt and sugar variations on properties and processing requirements of tomato puree and orange juice.