The advertisement for Hunt’s Tomatoes says they use “no harsh chemicals” to peel their canned tomatoes. This statement does not openly suggest other companies do use harsh chemicals, but it implies that they do. In fact, chemicals used to peel tomatoes is common. Hunt says it uses steam.
Having my interest aroused, I decided to look into the matter. Technically, Hunt is telling the truth. Nevertheless, the use of lye in the peeling of fruits and vegetables is anything but new or unusual. Although 70% of tomatoes are peeled using hot water or steam, approximately 30% of tomatoes are peeled using lye.
These facts are found in the publication by the University of California, Davis¹ entitled, Peelability and Yield of Processing Tomatoes by Steam or Lye. It discusses the peeling of two well-known tomato varieties by means of boiling water, steam, and lye peeling. Two of the control factors that affect results are temperature and exposure-time. Vacuum is employed to remove the loosened peel.
When the article mentions lye, it refers to either sodium hydroxide¹ (NaOH) or potassium hydroxide² (KOH). Pure lye, or even a strong water solution is harsh. It can be used to clean stopped drains. It is also used in the manufacture of paper, cellophane, and mercerized cotton. Thrown into the eyes, lye burns, and can even blind the victim.
So why is the use of lye among the tools used for peeling tomatoes? Ordinarily, tomatoes are harvested as an entire crop—when 90% of the yield is ripe. Of course, some of those tomatoes are a little beyond ripe. The goal is to peel the tomatoes with as little loss of fruit and as little softening as possible. This needs to be accomplished without diminishing color.
Although lye has the potential of hurting the individual coming into contact with it, the consumer is in no way faces exposure, as it is not part of the finished product. Although the advertisement is true, to the average consumer, it may as well be written in a foreign language. Lye is used in the manufacture of soap. It is used in the preparation of eating olives. For decades it was used by homemakers to remove hulls in the making of corn hominy. Even some cookie recipes list lye in the list of ingredients!
¹ also called caustic soda
² also called caustic potash
References or Resources:
- Seasoned Advice: Why is Lye Used in Some Recipes for Cookies?
- National Center for Home Food Preparation: Hominy without Lye
- The National Academie Press: Sodium Hydroxide