Someone recently asked me this question, so I figured it would be a good idea to clarify for all.
The concept of ChaNaN means that when a forbidden substance (like bacon) gets absorbed into a kosher food (like a meat stew), and there isn’t bitul b’shishim (a 1:60 nullification), that entire piece of kosher food becomes as if it is non-kosher itself—even though it began as 100% kosher. The stew is now treated like actual bacon.
Let’s break this down with a practical example:
Case:
• You cook a kosher meat stew.
• A small but noticeable amount of bacon falls in — let’s say 1/40th of the stew. That’s enough to impart flavor, so the bacon is not nullified.
• Now, according to all opinions, the stew becomes non-kosher because the forbidden flavor is present.
But now:
• That non-kosher meat stew falls into a large pot of chicken soup.
• The meat stew is only 1/40th of the chicken soup, and the original bacon is now 1/1600th (1/40 of 1/40).
• So the bacon flavor is completely gone, but the flavor of the meat stew itself remains.
Here’s the halachic split:
• According to Sephardic poskim (Shulchan Aruch):
Since the bacon flavor is no longer present, and ChaNaN does not apply in ta’arovet (liquid mixtures), the chicken soup remains permitted. The meat stew does not carry a status of bacon, and we evaluate only based on actual flavor of issur.
• According to Ashkenazic poskim (Rema):
The meat stew is now considered entirely non-kosher, and therefore it’s as if you dropped non-kosher meat into the chicken soup. If the flavor of the meat stew (even without bacon) is noticeable in the chicken soup, then the entire soup becomes forbidden. This is the halachic effect of ChaNaN — not because of bacon flavor, but because the entire piece is now a source of issur.
The Key Point:
This stringency is not a Torah law — it’s a chumrah accepted by Ashkenazic authorities, primarily the Rema, based on rulings of the Rosh and Tur. Sephardim do not follow this rule except in very specific solid cases, not in liquid mixtures.
Why This Is Rarely Relevant Today:
In modern food manufacturing, this kind of direct contamination followed by a second cooking or mixing stage virtually never happens.
• Ingredients are carefully portioned.
• If something non-kosher accidentally entered a batch, it is either nullified or discarded.
• Complex industrial mixtures almost never retain a distinct flavor of any forbidden component beyond detection.
Moreover, ta’arovet halacha is all about ta’am (flavor). And unless you are dealing with an actual kitchen scenario — like a home-cooked stew where something treif falls in and then transfers to another dish — the rule of ChaNaN does not apply.
Conclusion:
ChaNaN is a rabbinic stringency, applied by Ashkenazim in specific scenarios where a kosher item absorbed issur and becomes a new source of issur.
But in real-world practical kashrut, particularly in manufacturing, ChaNaN is rarely triggered.