Throughout human history, we've been working on food preservation techniques - methods to maintain the viability of our food supplies during periods of reduced availability.

You are roughly correct if you are only considering Pasteurization (18th century), industrial canning (late 18th and early 19th century), quick freezing (20th century).

These techniques do not cover the entirety of food preservation techniques. Not even close. For instance preserved cabbage such as sauerkraut in its various likely date back to prehistoric times, and was first described by Pliny the Elder in the first century AD.

Cheese, wonderful cheese, predates recorded human history. It's a fantastic way to preserve milk products. It is packed with calories and is highly portable. According to Pliny the Elder, it was a widespread enterprise in the Roman Empire.

There are many other examples of foods that predate your 1850 date, some predating recorded human history. Examples include smoked meats, lye cured fish (Lutefisk), aspics and jellies, and even simply cellaring or burying.

Of course there's also beer.

You might know something about industrial agriculture, but you need to get more 'edumaction' on food and history. Your grandmother would be embarrassed.