How Did Anyone Keep Meat Before Fridges? Take the Water Out

Bacteria and moulds need available water to grow, and salt removes it in two ways at once. It draws water out of the meat by drawing it across cell membranes, and it binds the water that remains so that the organisms cannot use it, which together reduce what is measured as water activity to a level at which spoilage organisms cannot function. The meat is not sterile and does not need to be, since the conditions simply make growth impossible for the things that cause spoilage while remaining tolerable for a few useful organisms. Drying continues the process, and the two together account for most of the preservation, with smoke, acidity and specific additives handling the remainder.

Traditions differ and the techniques recombine in many ways:

• •Dry curing, rubbing salt onto the surface and letting it penetrate over weeks
• •Brining, immersing in salt solution, which works faster and more evenly
• •Injecting brine, which is the industrial method and is far quicker still
• •Air drying in controlled temperature and humidity, over months for whole muscles
• •Fermenting, allowing bacteria to produce acid that lowers the pH
• •Smoking, which dries the surface and deposits antimicrobial compounds

Small quantities of nitrate or nitrite are used in most cured meats and they do specific jobs that salt alone cannot. They inhibit the bacterium responsible for botulism, which tolerates the low oxygen conditions inside a curing joint and produces a toxin that is among the most lethal known, and this is the reason the practice became standard rather than a matter of appearance. They also produce the characteristic pink colour by reacting with the pigment in muscle, and contribute significantly to the flavour. Against that, they can form compounds associated with increased cancer risk, which is the basis of health advice about processed meat. Products advertised as free of them generally use celery extract, which supplies the same chemicals from a plant source.

Months of hanging do a great deal more than remove water, and the changes are the reason anybody bothers beyond preservation. Enzymes naturally present in the muscle break proteins into smaller fragments and eventually into individual amino acids, several of which taste strongly savoury, which is the main source of the depth these foods have. Fats oxidise slowly, generating aromatic compounds that account for much of the characteristic smell, and the same process taken too far produces rancidity, so the balance is a matter of time and temperature. Moulds encouraged on the surface in several traditions regulate drying and contribute their own compounds. Salt concentrates everything remaining. A young ham and an aged one differ in ways that have nothing to do with how much water each has lost.

Traditional practice looks casual and rests on conditions that took generations to work out. The salt concentration must be sufficient throughout the piece rather than only at the surface, which depends on thickness, on time and on temperature, and an under-salted centre in a large joint is exactly where dangerous organisms grow. Drying too fast seals the outside and traps moisture within, which is a recognised fault with a name in every tradition that does this. Temperature during the early stage determines which organisms establish first. Humidity must be held within a narrow band for months. The traditions that produce these foods reliably encode all of this as fixed procedure, which is why following one exactly matters more than understanding it.

Salt draws out water and binds what remains, lowering the availability that spoilage organisms need, and drying continues the process. Dry curing, brining, air drying, fermenting and smoking combine differently in each tradition. Nitrate and nitrite are used mainly to suppress botulism rather than for colour, and the risk in improvising lies in an under-salted centre, drying too fast and holding the wrong temperature early on.