Which Foods Are Chametz?

Chametz: An Overview

One of the last jobs of cleaning the house for Pesach is to get all chametz out of the kitchen. Of course, the first things to be removed are those that are obviously chametz – bread, pasta, cookies, crackers, pretzels etc. Other foods can be identified by simply reading the ingredient panel, which shows that breakfast cereal, soy sauce, fish sticks, licorice, candy and many other foods often have wheat or flour (chametz) listed prominently. But only the most astute readers realize that the vinegar in their ketchup, the vitamins in the rice or milk, and the flavor in their favorite snack may in fact contain chametz. The goal of this article is to educate the reader of the many foods which potentially contain chametz, beginning with the more obvious and progressing to the more obscure.

Flour, Oats and Barley

If one of the five grains – wheat, barley, rye, oats and spelt – sits in water for more than 18 minutes it becomes chametz, and one may not eat, derive benefit from or own it on Pesach. In addition, Ashkenazim don’t eat kitniyot – a group of foods which includes (among other things) rice, corn, soy and their derivatives – but are allowed to own kitniyot foods on Pesach.

It is common practice that before wheat is ground into flour, the wheat kernels are tempered with water for many hours, and therefore flour should be treated as chametz (Mishnah Berurah 453:24). [In fact, matzah which isn’t baked especially for Pesach is made from tempered wheat and should also be treated as chametz!]. Similarly, all oats are heat-treated to prevent them from becoming rancid; if this heating is done with “wet” steam, the oats/oatmeal may be chametz. On the other hand, barley (a.k.a. pearled barley) is processed without water, and therefore a standard bag of barley isn’t chametz. However, some barley is steeped in water until the barley begins to sprout; this creates a product known as barley malt (a.k.a. malted barley, malt) which is definitely chametz.


The Torah says that one may not own se’or on Pesach. Are se’or and yeast the same thing? A quick lesson in bread baking will surprisingly show that se’or is yeast but yeast isn’t necessarily se’or!

Although a grain which soaks in water for 18 minutes is chametz, in order to make good bread one needs yeast. Yeast is the living microorganism which converts some of the flour into the carbon dioxide which fluffs-up the batter and causes it to “rise”. The air we breathe contains yeast, and therefore if one makes a batter of flour and water it’ll eventually rise even if no yeast is added, because yeast from the atmosphere will find their way into the batter. But most bakers don’t have the patience to wait all day for their bread to rise, so they add their own yeast into the batter to speed things up a bit.

The traditional method of collecting/creating yeast is as follows. Every day the baker would take one handful of dough out of the batter and not bake it. As the day went on, the yeast in that dough would multiply (and be joined by other yeast found in the air) to such an extent that that the batter would turn sour and inedible. This ball of concentrated yeast would be thrown into the next day’s batter to help that batter rise (and a handful of that batter would be taken out to be saved for the next day…). In English this concentrated yeast-ball is called “sourdough” due to its awfully-sour taste, and this is what the Torah calls se’or and forbids one from owning on Pesach.

However, one can also collect yeast from plant sources and produce it via fermentation. If yeast doesn’t contain any ingredients from the 5 grains (as it often doesn’t) it isn’t chametz even though it has the same characteristics as se’or (see Mechilta 9:19 on Shemot 12:19) and one may own it on Pesach. [The process of “fermentation” and the possible chametz concerns it raises will be discussed below]. Thus, se’or is concentrated yeast but the yeast which is commonly sold in stores is not se’or.

Brewer’s yeast is yeast recovered from beer production (discussed below). It is similar to se’or and one may not own it (derive benefit from it or eat it) on Pesach.

Beer and Whisky

If barley is soaked in water under proper conditions, it ferments into beer, and since the barley sat in water for more than 18 minutes, beer is chametz (Shulchan Aruch 442:5). Beer contains approximately 5% alcohol and people who want a drink with a higher alcohol content do the following. The grain is allowed to ferment until it reaches about 12-13% and then the alcohol is separated from (some of) the water using a process called “distillation” to produce whisky which contains 30-95% alcohol. The consensus of the Poskim is that whisky produced from one of the 5 grains is considered chametz even though it went through the process of distillation (see Shulchan Aruch Y.D. 92:8 & 123:24, and Mishnah Berurah 442:4). Even if the whisky is made from corn or another kitniyot grain, there are a number of other reasons why it may be chametz:

  1. The watery liquid that remains after distillation is called “backset” and is often used in creating another batch of whisky. Thus, even if the grain used in creating the whisky is kitniyot, the water may be from a chametz whisky.
  2. Before the yeast ferments the grain, the grain’s starch must be broken-down into individual glucose molecules, and this is traditionally done with barley malt (discussed above). Since the chametz barley malt plays such a crucial role in the creation of the whisky (and also dramatically changes the taste of the grain before it is fermented), the barley malt is considered a davar hama’amid and one may not own such whisky on Pesach (see Shulchan Aruch 442:5 and Mishnah Berurah 442:25).

As such, all types of whisky should be treated as chametz unless they are specifically certified as kosher for Pesach.


Vinegar is created when alcohol is (re)fermented, and the primary concern with vinegar is the source of the alcohol. As the name implies, malt vinegar is made from malt or beer which we’ve seen is chametz, and therefore malt vinegar is definitely chametz. In contrast, wine vinegar and apple cider vinegar are made from wine and apple cider which aren’t chametz. However, due to the possibility that the equipment used and/or the processing aids are chametz, it is prudent to only consume wine or apple cider vinegar which is certified as kosher for Pesach.

The more difficult question is the Pesach status of white distilled vinegar, as follows. White distilled vinegar is made from distilled alcohol (described above) and the most serious concern is whether the grain used was chametz (e.g. wheat), kitniyot (e.g. corn), or something innocuous (e.g. potatoes). Additional concerns stem from questions about the equipment, enzymes, yeasts, and nutrients used in creating the alcohol and vinegar. [The nutrients are generally batel b’shishim but some Poskim hold that since they are intentionally added to the vinegar they aren’t batel; this issue, discussed in Magen Avraham 442:1, Noda B’ Yehudah Y.D. II:56, Mishnah Berurah 447:14 and others, is beyond the scope of this article]. In addition, the fermentation of vinegar always begins with a “starter” taken from a previous batch of vinegar (similar to the way se’or is used) and if that starter is chametz, the entire batch will be forbidden.

The question of whether grain-based/distilled vinegar is chametz has far-reaching implications because many foods are preserved with vinegar (e.g. pickles, olives) and vinegar is a prime ingredient in many condiments (e.g. ketchup, mustard, mayonnaise, salad dressing), and in general it is distilled vinegar which is used in these applications. Certainly, any food containing vinegar shouldn’t be consumed on Pesach unless the food is specifically certified for Pesach use. But do the concerns with vinegar mean that we must destroy or sell all of the products in my pantry which contain vinegar?

As a result of the concerns outlined above, many Rabbanim recommend that people whose minhag is to not sell chametz gamur, shouldn’t sell (or retain possession) of vinegar-containing products on Pesach. However, others with knowledge of the food industry argue that due to the abundance of corn in the United States, the overwhelming majority of the vinegar sold and used in the United States does not contain chametz (although it does contain kitniyot). Therefore, since there isn’t any reasonable way for the average consumer to figure out whether the vinegar in their ketchup (for example) is chametz, they may rely on the rov (majority) and assume that the vinegar is not chametz at least to the extent that it may/should be sold to a non-Jew. As with all matters of halacha, one should consult with their local Rav. It is noteworthy that the aforementioned leniency does not necessarily apply to (a) vinegar or vinegar-containing products from other countries and (b) organic vinegar (even if it is produced in the United States, due to the difficulty in obtaining organic corn).

Pesach products are generally made with white distilled vinegar which is specially-made without any chametz or kitniyot concerns. However, some companies choose to substitute glacial acetic acid for the vinegar in their Pesach products. Glacial acetic acid is chemically identical to vinegar, but is made from petroleum feedstock as opposed to being fermented, and poses little Pesach concern.

Enzymes, Vitamins, Flavors and Other Complex Issues

Microbiology has played a great role in the advances in food technology in the past few decades. Food scientists have identified numerous microorganisms which can either serve as or help to create, enzymes (see below), vitamins (e.g. Riboflavin, Vitamin B12), flavorful chemicals (e.g. MSG) and other items (e.g. xanthan gum, citric acid, yeast). In addition, scientists have learnt new ways to react chemicals with one another (and use other methods) to create emulsifiers, acidulants, sweeteners, flavors and other chemicals (e.g. polysorbates, ascorbic acid, aspartame, esters, magnesium citrate). This technology has allowed food scientists to create an array of foods which were inconceivable 50 years ago, and to improve on the way that they produce “older” foods.

Of all these items, enzymes have arguably had the most far-reaching effect. Enzymes are chemicals which act as a catalyst for change in other items. A common example is rennet which causes milk to coagulate into cheese, but the range of uses goes well beyond cheese. One enzyme liquefies and sweetens corn into corn syrup so that another enzyme can make it even sweeter and become the high fructose corn syrup used to sweeten soft drinks. An enzyme is used to create the “right” kind of sugar molecule so that hard-candies won’t stick to the wrapper, and a different one makes sure that beer doesn’t get cloudy when its put in the refrigerator.

The kashrus issues raised by all of this technology is beyond the scope of this article, but one issue is quite relevant to our discussion. One of the prime ingredients used in making just about all of the items discussed above is “glucose” (a.k.a. sugar), and glucose can be created from any starch, which means that these items may be wheat (chametz), corn or rice (kitniyot), sweet potatoes (kosher for Pesach) or something else, depending on what is available in the country where the glucose is being produced. This issue is further complicated by the emergence of the “global marketplace” where it may be cheaper to buy xanthan gum from France or China than from the local producer. Additionally, many of the ingredients listed above are used in tiny proportions which would theoretically be batel b’shishim, and Poskim have taken different positions as to which of these serve as a davar hama’amid and/or a milsah d’avidah lit’amah, which can’t be batel.

In light of the seriousness of eating chametz on Pesach, it’s obvious that no one would consider eating any food on Pesach which contains (or may contain) any of these ingredients, unless the food is certified as kosher for Pesach. [Many children and adults must consume baby formula, soy/rice beverages or nutritional supplements (which cannot be certified for Pesach since they contain kitnios) and require information as to whether those items contain chametz. That issue is beyond the scope of this article and will IY”H be dealt with separately]. Some Rabbanim say that for the same reason one shouldn’t own any of these items on Pesach, but as noted above regarding vinegar, others argue that one may rely on the fact that the overwhelming majority of these items sold and used in the United States do not contain chametz (although they contain kitniyot). As with all matters of Halacha, one should consult with their local Rav.

Chag Kasher V’sameach

OU Kosher Staff