Even with 25 years experience as a journalist and investigator of the food chain, Joanna Blythman still felt she had unanswered questions about the food we consume every day. How 'natural' is the process for making a 'natural' flavouring? What, exactly, is modified starch, and why is it an ingredient in so many foods? What is done to pitta bread to make it stay 'fresh' for six months? And why, when you eat a supermarket salad, does the taste linger in your mouth for several hours after? 'Swallow This' is a fascinating exploration of the food processing industry and its products - not just the more obvious ready meals, chicken nuggets and tinned soups, but the less overtly industrial - washed salads, smoothies, yoghurts, cereal bars, bread, fruit juice, prepared vegetables.