The minhag of Ashkenazim is to apply the halachos of Chatichah Na’ses Nevaila (ChaNaN) to all issurim, not just to basar b’cholov; (Rema Y.D. 92:4). Therefore, if one kezayis of any issur is cooked with 9 kezaysim of heter, we would have 10 kezeysim of issur. If these 10 kezaysim of issur, are subsequently cooked with 90 kezaysim of heter, although this is more than 60 times the original kezayis of issur, nevertheless because we say ChaNaN the entire mixture becomes assur. However, there is a distinction between the original 10 kezaysim and the subsequent 90 kezaysim. The original 10 kezaysim are assur mid’oraisah because they were mikabel ta’am issur (ta’am k’ikar); however, the later 90 kezaysim are only assur mid’Rabbanan because of ChaNaN b’shar issurim.
As it name implies ChaNaN applies primarily to chatichos. Regarding mixtures that are lach b’lach (homogenous liquid blends) the Rema paskens that in situations of hefsed mirubah we do not say ChaNaN b’shar issurim. This implies that although the ikar halachah is not to say ChaNaN lach b’lach, nevertheless one may only be maikel b’hefsed mirubah. One should contact the office before making any decisions regarding what is considered a hefsed mirubah. It should be noted that ChaNaN lach b’lach applies to both cold and hot mixtures of liquids, or to powders that are dissolved in liquid.
Lach b’lach b’issur d’rabbanan
Igeros Moshe (Y.D. II:36) writes that there is room to be maikel not to say ChaNaN by an issur d’rabbanan lach b’lach. However, he cautions against relying on this heter unless there is a tzorech. Likewise the policy of the OU has been to use this only as a tziruf or in cases of shas hadchak.
Since ChaNaN is d’rabbanan, can we apply the rule safek d’Rabbanan l’hakel?
This is a disagreement amongst Poskim. Though Maharil apparently held that safek ChaNaN is also assur, Taz (Y.D. 92:12) disagrees and held that one can say safek d’rabbanan li’kula. Pri Migadim (92:12) explains the Maharil as follows. Since we pasken that the original 10 kezaysim (as per the example above) become vadai assur (safek d’oraisah lichumra), therefore the shailah of whether we say ChaNaN on those 10 kezaysim is viewed as a safek d’oraisah shenisgalgel le’di’Rabbanan. The Pri Migadim concludes that one should not be maikel except b’hefsed mirubah. However, Rav Schachter points out that regarding safek ChaNaN lach b’lach (which itself is mutar b’makom hefsed mirubah) one may be maikel1. In factories, lach b’lach mixtures are the more common scenario. If this mixture entails a safek, we do not say ChaNaN.
Example: One liter of an uncertified ingredient (that can be kosher or non-kosher) was mistakenly dissolved into 20 liters of water. Then an additional 50 liters of water were added. In this case the uncertified ingredient would be batel in the product. We would not say ChaNaN since it is a case of safek issur lach b’lach.
Do we say ChaNaN on mixtures of powders?
Rav Belsky has said that we do not say ChaNaN when there is a mixture of cold kosher and non-kosher powders, because there is no transfer of ta’am. In this regard powders are considered like yaveish b’yaveish about which we do not say ChaNaN2. Although regarding chametz we pasken that mixtures of powders are considered lach b’lach and we therefore do not say chozer v’niyur3, nevertheless regarding the potential issur of ChaNaN lach b’lach we can be maikel to view the powders as yaveish4, especially because there is no transfer of ta’am.
Example: A 50 pound bag (approximately 10 gallons) of powder stabilizers which is made up of 40% non-kosher gelatin and 60% other ingredients is dissolved into 500 gallons of milk. Do we need to kasher the keiliim? No, a thorough cleanout is all that is needed. Although the stabilizer is 2% of the product, because we do not say ChaNaN, we need only be concerned with the gelatin which is only .8% of the product. Although gelatin can be considered a davar hama’amiid which is not batel, still the keilim are not treif because the ta’am is batel.
ChaNaN with pork and beans
Many are startled to learn that the amount of pork in canned “pork and beans” is often less than 1.6%. Does that mean that there is really no need to kasher the keilim? In one particular plant the beans are cooked and then drained and filled hot into open cans. Chunks of pork and lard are manually added to each can. At this point the top layer of beans becomes assur and those beans become ChaNaN5. Saying ChaNaN on the top layer of beans will basically double the amount of issur in the can. Then hot brine is poured over the beans, the cans are sealed and retorted. The entire can would now become ChaNaN, unless the beans and brine are always 60 times the volume of the chazar and the top layer of beans. Even if the amount of chazar is less than 1%, all the equipment used for the pork and beans needs kashering.
1 Pri Migadim (Kellalim B’hora’as Issur V’heter s.k. 6) generalizes this concept and writes that cases which are mutar b’hefsed mirubah become mutar lichatchila when there is also a safek.
2 Rema Y.D. 92:4
3 Mishnah Berurah 453:17
4 See Teshuvas Beis She’arim Chaylek O.C. siman 4 who makes a similar argument
5 See Rema Y.D. 92:4 “או שהחתיכה כולה חוץ לרוטב”