Department of Engineering Science, University of Auckland, Auckland, New Zealand.|Gut Health and Food Safety Research Programme, Institute of Food Research, Norwich, United Kingdom.|Gut Health and Food Safety Research Programme, Institute of Food Research, Norwich, United Kingdom.|Gut Health and Food Safety Research Programme, Institute of Food Research, Norwich, United Kingdom.|Gut Health and Food Safety Research Programme, Institute of Food Research, Norwich, United Kingdom.|School of Mathematics and Statistics, University of Sheffield, Sheffield, United Kingdom.|Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom.|Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Oxford, United Kingdom.