Putting Up Tomatoes:
What the 1930s Kitchen Knew

The Bureau Behind the Bulletin

Louise Stanley had led the USDA Bureau of Home Economics since 1923. Under her direction, the Bureau produced research on nutrition, household budgets, clothing construction, and food preservation — practical science aimed at the household rather than the farm or the processing plant. Stanley herself held a doctorate in chemistry from Yale. She brought a scientist's precision to questions that had previously been left to tradition and guesswork.

Farmers' Bulletin 1762 was a revision of an earlier bulletin, No. 1471, which Stanley had published in 1926. The 1936 edition reflected a decade of additional research and a changed context. The Depression had made home food preservation more economically significant than at any point since World War I. Extension agents across the country reported a sharp uptick in canning activity as families sought to reduce cash expenditures on food. The government's interest in getting the science right was no longer purely academic.

The Bureau's approach to tomatoes reflected the scientific understanding of the time: tomatoes were a high-acid food, and high-acid foods could be safely preserved using a boiling water bath because the acidity prevented the growth of Clostridium botulinum, the bacterium responsible for botulism. This was correct as far as it went. The complication — which took another four decades to fully surface — lay in how "tomato" was being defined.

What the Bulletin Taught

The 1936 bulletin's guidance on tomatoes was methodical. Stanley and Stienbarger distinguished between whole tomatoes, crushed tomatoes, and tomato juice, providing separate processing times for each. They specified selecting firm, fully ripe, disease-free fruit — not overripe, not from frost-killed vines. They detailed the hot pack method (heating tomatoes before filling jars) and noted that it produced a denser, more consistent product than cold pack. They specified processing times in a boiling water bath: 15 minutes for pints, 20 minutes for quarts of whole tomatoes at sea level.

Much of this guidance transfers directly to a modern kitchen. The emphasis on firm, undamaged fruit reflects a real principle: damaged or overripe tomatoes are more likely to harbor mold and more likely to have elevated pH. The hot pack preference aligns with current NCHFP recommendations. The attention to headspace and proper lid seating — ensuring no food residue on the jar rim before applying the lid — remains exactly as important today.

Where the 1936 guidance departed from current practice was on one specific point: it did not require acidification. Stanley and Stienbarger treated tomatoes as reliably high-acid and processed them without any supplemental acid. At the time, this was reasonable. The tomato varieties in widespread cultivation in the 1930s were generally more acidic than modern commercial and heirloom varieties. The systematic study of pH variation across tomato varieties had not yet been done.

How the Science Changed

The problem with treating all tomatoes as reliably high-acid became apparent slowly. In early 1974, the Centers for Disease Control reported two deaths from botulism traced to home-canned tomatoes. The public health investigation identified a combination of factors: overripe tomatoes with elevated pH, and processing methods that left surviving spores in conditions where they could produce toxin. Consumer researchers initially suspected the "new, low-acid" commercial varieties developed in the 1960s and 1970s for machine harvesting and long-distance shipping. Those varieties were, in fact, less acidic than traditional types.

The response was systematic. USDA and university researchers measured the pH of dozens of tomato varieties under different ripening conditions. They found that while most tomatoes fell below the 4.6 threshold, enough did not — particularly over-mature fruits, fruits from vine-killed plants, and certain modern cultivars — that the earlier assumption of universal high acidity could no longer be relied upon. The solution was straightforward: require a small amount of supplemental acid in every jar, regardless of variety. Bottled lemon juice and citric acid both work. The processing times stay the same.

The USDA incorporated the acidification requirement into its revised guidance in the 1980s. The 1988 Complete Guide to Home Canning, which replaced all previous separate bulletins, made it mandatory. The National Center for Home Food Preservation, established at the University of Georgia in 2000 to serve as the ongoing scientific authority for home food preservation in the United States, has maintained the requirement since.

What Still Transfers

The 1936 guidance was not otherwise wrong. Its core framework for tomato preservation — select good fruit, use proper jars, process in a boiling water bath for a defined time, check seals before storing — remains the current procedure. The specific attention Stanley and Stienbarger paid to jar preparation deserves credit. They wrote precisely about washing jars in hot soapy water, checking for nicks and cracks at the rim, and ensuring clean contact between the jar and the lid gasket. These are not procedural formalities. A failed seal on a jar of canned tomatoes means a jar that may not show visible signs of spoilage while harboring a hazard.

Their insistence on processing time — not sealing method — as the standard for safety was also correct and important. An alternate method called open-kettle canning was common in American households at the time: fill a hot jar with hot food, seal it immediately, and let the cooling process create a vacuum. Stanley and Stienbarger did not endorse this method for vegetables, and their instinct was sound. Open-kettle canning has since been explicitly rejected by the USDA because the food is not heat-processed after sealing. Bacteria that survived the initial cooking can survive in an open-kettle jar. The NCHFP now lists open-kettle canning as an unsafe method.

The bulletin's fruit and vegetable selection criteria also hold. Choosing firm, vine-ripened tomatoes is not merely about flavor — overripe or damaged fruit is more likely to carry mold spores and more likely to have elevated pH. Stanley and Stienbarger's prohibition on canning tomatoes from frost-killed or dead vines appears in current NCHFP guidance in almost identical language, nearly ninety years later.

The Wartime Years and What They Produced

Bulletin 1762 was revised in 1938, 1941, and 1942. By the time the 1942 edition appeared, the country was at war and the context had shifted again. Home canning was now a patriotic act, not just a household economy measure. Victory garden tomatoes needed to be preserved. Commercial canners were directed toward military supply. The extension offices that distributed Bulletin 1762 became community food preservation centers, helping households that had never canned before work through the process.

The USDA published a separate wartime folder specifically on tomatoes in 1943 — AWI-61, "Canning Tomatoes" — a simplified one-page guidance sheet that distilled Bulletin 1762's tomato section into the most essential steps. At the same time, community canning centers were established in schools and churches in areas with large Victory garden outputs, equipped with commercial-scale pressure canners and staffed by extension agents. The infrastructure that emerged during the war years trained a generation of American households in food preservation techniques that many had never previously practiced.

What a Modern Household Takes From This

The practical lesson from Farmers' Bulletin 1762 is not that old methods were dangerous — they were not, in the main — but that food preservation science is a living discipline that requires current sources. The 1936 bulletin represented the best available guidance of its time. The acidification requirement was added because researchers later identified a real gap. A household canning from a pre-1988 guide, or from an inherited family practice that predates the acidification requirement, is working from incomplete information on one specific point.

Beyond that specific update, the 1936 approach to tomato preservation is a useful model for thinking about home food storage more broadly. Stanley and Stienbarger were not interested in novelty or in selling equipment. They were interested in helping households do a specific thing reliably and safely. Their guidance is organized around the question: what can go wrong, and what prevents it? That is the right frame. Good fruit selection prevents spoilage at the source. Proper jar preparation prevents seal failure. Adequate processing time prevents bacterial survival. Correct storage prevents long-term degradation.

Home-canned tomatoes are useful year-round in a household that cooks from scratch. A shelf of properly processed tomatoes represents independence from the retail supply chain for one of the most versatile pantry staples. That was true in 1936. It remains true now. The method has not changed much. The one update that matters — add the acid — takes about thirty seconds per jar.