Squashing, Filtering, and Other Ways We Process Food

As I have discussed throughout this book, mankind has relied on heating to preserve and make safe our food for a very long time, even long before the science of how and why this works was understood. However, clearly using heat to process However, clearly using heat to process food is a rather blunt tool, sometimes as subtle in its effects as hitting it with a club or bat. Just as it kills bacteria, molds, and other microorganisms, it inflicts collateral damage on the sensory and nutritional quality of the food. The greater the level of kill, and hence stability and safety conferred, the greater damage to the “fresh-like” characteristics of the food has usually been caused. A question could then be posed as to whether, instead of applying such a crude and damaging (although undoubtedly effective) treatment, we could treat food with more of a surgical-scalpel or laser-focused treatment, which zoomed in on and very specifically destroyed the target microorganisms while leaving the surrounding food as little changed as possible. This is the target of so-called minimal (sometimes called invisible) processing, and today there are a range of technologies that have promise for achieving this goal. Indeed, because of the desirability of such an outcome, this has been thus one of the most active areas of research on food processing in recent years. We have encountered the importance of pressure several times already in this book, usually in how its manipulation can affect properties of water such as boiling. Pressure has another important application in food processing, though, in that it can replace heat as the physical force we apply to achieve desirable change in food. In food processing circles, high-pressure (HP) processing is often referred to as a novel processing technology, but in fact it has been around for quite a long time. Remarkably, around the same time that Pasteur was explaining how heat works in terms of preserving food, on the other side of the Atlantic an American scientist called Bert Hite at the West Virginia Agriculture Station was doing experiments on his own homemade pressure-generating apparatus.