Articles

By Rabbi Dovid Cohen, Administrative Rabbinic Coordinator

Q. What is freeze-drying and what are its kashrus implications?

A. The general idea of “drying” is that removing the moisture/water from a food prevents it from spoiling (since the microorganisms that cause spoilage won’t function in that environment).  The simplest and cheapest way to do that is to put the food into a hot (or warm) chamber, which causes the water to evaporate.  However, in cases where it is important to maintain the food’s taste and structure, companies may opt for “freeze-drying”, which operates as follows:  The food is placed in a single layer on trays and frozen solid.  The trays are put into a sealed chamber where all air is removed to create a vacuum, and then the trays are gently heated for 16-24 hours.  Due to the vacuum and precisely controlled environment, the moisture goes from being a solid (i.e., frozen in the food) to a vapor/gas, without ever being a liquid (i.e., water).  [Some common examples of freeze-dried foods are the vegetables in instant soups, and the berries in some breakfast cereals.]

The machinery used for freeze-drying is complex and expensive and can also be used for many different foods.  Thus, it is unlikely that a vegetable or herb company will own their own freeze-dryer.  Instead, they will send their product to a freeze-drying company that will process their foods, and on other days will use the same machines for all types of other things, such as pork, shrimp, ice cream, or yogurt.  For this reason, any food that is freeze-dried requires hashgachah to ensure that the equipment is kosher.  [The trays that the food is on requires kashering, but it is not as clear whether the chamber (which has no direct food contact) also does.  That issue is beyond the scope of this article.]

What about if herbs are freeze-dried?  Will that affect the bugs found in the herbs?  It is generally accepted that if food is put into an oven to dry it out, any insects that were on/in that food become permitted.  This is based on a halacha that bugs which dry out for 12 months are like “dust” and are permitted, and the Poskim say that heat drying has a similar effect.  At first, some contemporary Poskim thought that since freeze-drying is such a gentle process, it does not have the same effect as heated drying, and, therefore, the bugs would remain forbidden.  However, they then tested this by intentionally freeze-drying several insects.  The bugs retained their shape and form, but as soon as someone touched them, they disintegrated into a pile of dust.  This indicated that freeze-drying had the same effect as (heat drying and) aging the insects for 12 months, and removes that kashrus concern.

This article first appeared in the Let’s Talk Kashrus column, Yated Ne’eman, November 22, 2024.