Next Article in Journal
High Pressure Processing of Bivalve Shellfish and HPP’s Use as a Virus Intervention
Next Article in Special Issue
Effect of Radio Frequency Heating on Yoghurt, II: Microstructure and Texture
Previous Article in Journal / Special Issue
Effect of Particle Orientation during Thermal Processing of Canned Peach Halves: A CFD Simulation
Article Menu

Export Article

Open AccessArticle
Foods 2014, 3(2), 318-335;

Effect of Radio Frequency Heating on Yoghurt, I: Technological Applicability, Shelf-Life and Sensorial Quality

Department of Chemistry and Pharmacy, Emil Fischer Centre, Friedrich-Alexander Universität Erlangen-Nürnberg, Schuhstr. 19, Erlangen 91052, Germany
Fraunhofer Institute for Process Engineering and Packaging (IVV), Giggenhauser Str. 35, Freising 85354, Germany
Author to whom correspondence should be addressed.
Received: 27 February 2014 / Revised: 14 April 2014 / Accepted: 4 May 2014 / Published: 15 May 2014
(This article belongs to the Special Issue Thermal Processing of Foods)
Full-Text   |   PDF [835 KB, uploaded 15 May 2014]   |  


This first part of a two-part study focuses on the technical feasibility of applying radio frequency (RF) heating at different temperatures (58, 65 and 72 °C) to a stirred yoghurt gel after culturing. For comparison, a convectional (CV) heating process was also applied. The aim was to increase the yoghurt shelf-life, by preventing post-acidification and the growth of yeasts and molds. At the same time, the viability of lactic acid bacteria (LAB) was investigated in view of existing legal regulations for yoghurts. Additionally, the yoghurt color, aroma and taste profiles were evaluated. It was found that the application of RF heating was effective for the rapid attainment of homogenous temperatures of 58 and 65 °C, respectively. For RF heating at 72 °C, it was not possible to establish a stable heating regime, since in some cases, there was significant overheating followed by strong contraction of the yoghurt curd and whey separation. Hence, it was decided not to continue with the RF heating series at 72 °C. In the case of CV heating, heat transfer limitations were observed, and prolonged heating was required. Nevertheless, we showed that yeasts and molds survived neither the RF nor CV heat treatment. LAB were found not to survive the CV treatment, but these beneficial microorganisms were still present in reduced numbers after RF heating to 58 and 65 °C. This important observation is most likely related to the mildness of RF treatment. While post-acidification was not observed on yoghurt storage, slight color changes occurred after heat treatment. The flavor and taste profiles were shown to be similar to the reference product. Furthermore, a trained sensory panel was not able to distinguish between, for example, the reference yoghurt and the RF 65 °C sample by triangular testing (α = 5%), showing the potential of novel strategies for further improvements of heat-treated yoghurt. View Full-Text
Keywords: heating; pH; radio frequency; sensory; shelf-life; storage; yoghurt heating; pH; radio frequency; sensory; shelf-life; storage; yoghurt

Figure 1

This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

Share & Cite This Article

MDPI and ACS Style

Siefarth, C.; Tran, T.B.T.; Mittermaier, P.; Pfeiffer, T.; Buettner, A. Effect of Radio Frequency Heating on Yoghurt, I: Technological Applicability, Shelf-Life and Sensorial Quality. Foods 2014, 3, 318-335.

Show more citation formats Show less citations formats

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Foods EISSN 2304-8158 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top