Chametz Mixtures on Pesach

Everywhere else in kashrus, a forbidden trace that falls into sixty times its volume of permitted food is nullified. On Pesach that stops working.

Chametz on Pesach is not nullified even b'mashehu — in the smallest quantity there is. A crumb in a stockpot forbids the whole pot, and not only to eat: the mixture is forbidden in benefit too.

That one departure from the ordinary rule of bitul explains most of what Pesach preparation looks like.

Why chametz is treated this way

Three reasons are given, and they are worth separating because they do not all reach the same answer.

1. The severity of chametz itself. One is not separated from it all year — it is an ordinary permitted food for fifty-one weeks — so the risk of lapse is real. And eating it on Pesach carries kares.
2. It is a davar sheyesh lo matirin — something that will become permitted later. After Pesach the mixture is permitted again, and the rule is that anything with a future permit is not nullified even in a thousand. This is the Rambam's reason.
3. The Torah's demand goes beyond eating. Chametz must not be seen or found in your possession, which is not true of other forbidden foods.

Where the reasons diverge

Here is the case that tells them apart. Chametz falls into a dish on erev Pesach, after midday but before the festival begins. Is it nullified in sixty?

• On the davar sheyesh lo matirin reason: no. It already has a future permit, so nothing has changed.
• On the severity reason: yes. At that hour there is no kares for eating it, so the stringency has not yet attached and it behaves like any other prohibition.

The accepted position follows the first reason — the severity of chametz — so chametz that fell in on erev Pesach is nullified in sixty. It is a clean illustration of a reason doing real work rather than decorating a conclusion.

The same logic gives two further limits. The mashehu stringency applies only during the seven days of Pesach — not on erev Pesach from midday until nightfall, when the prohibition is only a lav. And a mixture formed on the eighth day in the diaspora, which is rabbinic, is likewise nullified in sixty.

Nullified before Pesach stays nullified

This is the practically important one. Where chametz mixed into food before Pesach and there was sixty against it, it was nullified then — and it does not reawaken on Pesach to forbid b'mashehu.

The mixture may be eaten during Pesach. And this holds even where nobody discovered the mixture until Pesach had already started.

The worked examples in the sources:

• Wheat rained on, or that fell in water, mixed into a much larger quantity of wheat with sixty against it — may be ground and baked into matzah before Pesach.
• Raisin wine made before Pesach, where split wheat or barley grains are found in the soaking water — since there is taste and not substance, and sixty against the grain, it is not reawakened. The wine is fit even for the four cups.
• Bread soaked in wine for days, then removed and strained before Pesach through a strainer fine enough that no crumbs passed — permitted to drink on Pesach.
• Barley beer, which is outright chametz, mixed before Pesach with other drinks with sixty against it — permitted. And where there is not yet sixty, one may add more liquid before Pesach until there is, and nullify it then.

Where Ashkenazi practice differs

The permissive treatment above is for a liquid-in-liquid mixture, and on that the Rema agrees — barley beer diluted before Pesach is permitted for Ashkenazim too.

But where a solid was mixed in, or where a mixture is merely suspected, the Rema forbids on Pesach — bread that fell into wine, for instance, even after it was taken out, because crumbs may have stayed behind and will give taste on Pesach. Ashkenazi communities follow this.

A wheat grain in the food

The classic case, and the answer turns on one observable fact: is the grain split?

One further point on the forbidden case, which shows how carefully the benefit prohibition is applied: the dish may still be sold to a non-Jew. Chametz on Pesach is forbidden in benefit — but the buyer is not paying anything extra for the taste of one wheat grain, so the seller derives no benefit from the chametz at all.

For inedible chametz, which runs on different rules, see chametz nuksheh. For the wider picture, Pesach basics.

A real mixture in your own kitchen is a question for your rav — and the split-grain distinction in particular is one to have checked rather than judged.