How It's Made: Mayonnaise

According to one theory, mayonnaise originated in the town of Mahon in Spain, where it was known as salsa mayonesa. Mayonnaise makes sandwiches zestier, turns canned tuna into tuna salad, hard-boiled eggs into egg salad, and is a creamy dip for french fries, Belgian style. Mayonnaise recipes vary, but all have eggs and oil as the main ingredients. The eggs can be all yolks, all whites, or a combination of both. At this mayonnaise factory, the raw eggs arrive in liquid form by tanker truck. They've been pasteurized to kill off salmonella and other common bacteria. The egg supplier has also cleaned and sealed the tank valve, an additional food safety precaution. A worker clamps a sanitary evacuation hose to the tank, then with a few blows of a mallet, releases the valve. A pump draws the eggs through the hose into a refrigerated receiving tank. The second main ingredient, soybean oil, arrives by a railway tanker car. Like all bulk ingredient deliveries, for food safety, the tank is sealed at the supplier to ensure it isn't opened prior to arrival here. A pumping system transfers the oil to a large holding tank. Meanwhile, factory workers weigh out the ingredients that make up this company's secret blend of spices. Next, they mix this spice blend with white vinegar, cider vinegar, and salt. Then they add liquid natural flavors. They pour this mixture into a large tank of room temperature water, producing what they call a slurry. The raw eggs, meanwhile, have been transferred into a large refrigerated holding tank. So now there are three holding tanks at the ready, a slurry tank, an egg tank, and an oil tank. A computerized proportioning system extracts the required amount from each tank and sends it to a mixing vessel. A couple of minutes of mixing at high agitation merges the eggs, oil, and slurry into tangy, creamy mayonnaise. The factory draws samples periodically and sends them to its quality control department for analysis. The lab technicians there evaluate several criteria, such as color, consistency, and of course, flavor. In this test, for example, they mix the mayo with phenolphthalein, a pH level indicator, and deionized water to check the acidity level. Once the mayonnaise passes quality control inspection, this rotary filler dispenses it into recyclable polyethylene jars. It fills each jar in just a quarter second. The next machine twists on a plastic cap. Inside the cap is a foil seal. This machine uses targeted induction heat to fuse the seal to the rim of the jar without heating the mayonnaise in the process. The seal preserves freshness and indicates the jar wasn't tampered with after leaving the factory. The labeling machine glues on one end of the label, spins the jar to wrap the label around, then glues down the other end. The quality control lab also performs some post-production spot checks. In this test, technicians use a machine called a viscometer to measure the product's consistency. The factory also packages its mayo into single-serving pouches. They're made of polyethylene film on one side, foil printed with the product label on the other. This multitasking machine forms rows of pouches, inserts about 4 ounces of mayonnaise per pouch, then seals and separates the pouches. These pouches are shipped to ready-made sandwich vendors and fast food restaurants whose customers need mayo on the go.