If you cook with fresh tomatoes at home, you probably know how to peel them by scoring the skin with an "x" and dropping them into boiling water for a few seconds. The skin is then easy to peel right off under cold water, and the tomatoes are ready for your recipe. The process takes just a few minutes. But if you're in a hurry to get dinner on the table, you can skip the peeling (and usually the seeding and dicing) by simply opening a can of already processed tomatoes.
Time is money, and in the arena of food production, labor and food waste represent dollars spent. Thus the mass producers of canned foods came up with a much more efficient means of removing the skin from tomatoes by using lye. Tomatoes are plunged into a bath of hot water and a caustic base of either Sodium Hydroxide (NaOH) or Potassium Hydroxide (KOH) for about 20 seconds. The tomatoes are then passed over a set of rollers which mechanically remove the peel. Years of research have been put into the specifics of chemically peeling produce. The optimal concentration and temperature of the lye solution, along with the amount of time the fruit spends in the solution, have been carefully studied and tested for decades to hone this process. The objective has been to ensure the tomatoes maintain the texture, color, and overall appearance desired by consumers.1 2
USDA inspection assures consumers that residual chemicals in food are at safe levels for consumption. However, disposal of the lye solution has posed a problem for some larger manufacturers in meeting water quality standards required by federal and state governments. California regulations are particularly stringent in this area, and have made waste disposal cost prohibitive to manufacturers, forcing some companies to find a more environmentally friendly option.3Steamy Alternatives
In the last few years, some manufacturers have looked into a more natural means of removing tomato skins: flash steam processing. In this procedure, the tomatoes are loaded into a large metal tube where they are quickly exposed to pressurized steam, heating the skins, but not the flesh of the fruit underneath. The steam is then quickly vacuumed out of that space which helps to loosen the skins. From there, the tomatoes are passed across rollers, similar to the final step of the chemical peeling process, and the remainder of the peel is removed there.1
, a subsidiary of the major food production company, ConAgra Foods
, began marketing their canned tomato products as peeled by steam, even registering the term, "FlashSteam," as a brand trademark.4
Heinz began to follow suit with their Escalon Premier Brand tomatoes,5
although does not yet make the same claim for other products of the parent company.
How does the consumer make an informed decision?
If you're concerned about the way your tomatoes are processed, the first place to look is the label on the packaging:
Technology Marches On
- According to the USDA National Organic Program, processed tomatoes claiming to be "Organic" cannot be peeled with lye6 7 so canned tomatoes and other processed tomato products cannot claim to be organic if they are chemically peeled.
- Claiming to be "natural" is an oft-used tactic by advertisers. Thus, if a manufacturer is able to tout the fact that their tomatoes are "naturally steam peeled," they're likely to put that on the label for all to see. If they're not advertised as such, you can likely assume those tomatoes are chemically peeled.
- Most food manufacturers have websites listed on their food labels, and those websites often list nutritional information and production methods. You can also usually contact the company directly via their website with any further questions you may have.
The peeling of tomatoes and other produce may soon go even more high tech. Although steam processed produce is better for the environment, it sometimes results in a lesser quality product by affecting the color and texture of the fruit. Food scientists at the Agricultural Research Service, a division of the United States Department of Agriculture, are currently testing a means of peeling tomatoes via exposure to infrared (IR) heating. The process uses no chemicals, nor water, and is thus being termed, "IR dry-peeling." IR dry-peeling appears to maintain the color and texture of tomatoes better than steam peeling, and does not have the deleterious effects on water quality of lye peeling. And because the skins are not contaminated with the salts
left over from chemical processing, they can be used in animal feed and other value added tomato products. Although not yet being used in mass production, the USDA is optimistic that IR dry-peeling will soon be the preferred method of tomato peeling.
Garcia, E., Barrett, D. M. 2005. "Peelability and Yield of Processing Tomatoes by Steam or Lye." Department of Food Science and Technology, University of California, Davis.
Matthews, R. F., Bryan, H. H. 1969. "Lye Peeling of Florida Tomatoes - Effects of Time, Temperature, and Concentration." Florida State Horticultural Society.
Pan, Zhongli. 2012. "Development of Sustainable Tomato Peeling System by Using Infrared Radiation Heating." Processed Foods Research.
USDA Agricultural Research Service. Web.4
"The Hunt's Tomato Difference." www.hunts.com/the-flashsteam-difference
. 2012. Web.5
"The Escalon Difference." www.escalon.net/escalon-difference.aspx
. 2012. Web.6
"National List of Allowed and Prohibited Substances." USDA Agricultural Markeing Service. www.ams.usda.gov/AMSv1.0/NOPOrganicLabeling
. 2012. Web.7
"Nonagricultural (nonorganic) substances allowed as ingredients in or on processed products labeled as "organic" or "made with organic." 7:205:G:605 e-CFR. www.ecfr.gov
. December 19, 2012. Web.