Lash (Part 8) Instants Foods

  • Rav Yosef Zvi Rimon

Lash, Part VIII

 XIV) Instant Foods


Is one allowed to make instant soup, pasta or mashed potatoes on Shabbat?  How may one prepare instant baby food or formula on Shabbat? 


In this, our final shiur on the melakha of lash, we will examine the complex issue of how this prohibition relates to the increasingly pervasive phenomenon of the past half-century: instant food.  Very often, preparing these foods means adding liquid to grains or powder and stirring the mixture.  Is this lisha?


We must note that aside from the issue of lash, preparation of these foods needs to avoid the melakha of bishul (cooking).  To summarize the conclusion of my analysis as pertinent to this discussion, one may not prepare these in a primary vessel (the one “on the fire”) or in secondary vessel (which one pours into from the primary vessel), there is room to do so in a tertiary vessel (poured into from the secondary vessel).  (Nevertheless, it is best not to do this regularly, since this resembles cooking on Shabbat.)  In cases where the bishul issue has been overcome, the question then arises: is there a problem of lisha in preparing instant food? 


To answer this, we must differentiate among three types:

1.    If the instant food is a liquid, such as soup, or of similar consistency, there is generally no problem of lisha.

2.    If the instant food consists of pasta with sauce and the like, it may be as liquid as soup; but at times, the mixture is more viscous, and the sauce makes the pasta cohere.

3.    If the instant food consists of a powder, the water may sometimes turn the powder into a very thick mass; this is the case with instant mashed potatoes (potato puree).  In this case of a belila ava (thick mixture), sometimes the very addition of water creates the belila, without any further action, and sometimes there is a need to stir it so that a mass will form. 


In the second case — e.g., pasta with tomato sauce — the resultant mixture can be pourable and thus defined as a belila rakka (thin mixture), and sometimes it is defined as a belila ava.  A belila rakka may be created with a shinnui (alteration), according to the rules we mentioned in our previous shiurim.  In other words, one must alter the sequence of ingredients — instead of putting boiling water in a container of instant food, one should empty the contents into another vessel, pour hot water into the now-empty container and afterwards put the instant food back into its container.  In addition, one should do the mixing with a shinnui, e.g., sheti ve-erev (crosswise).[1]


Nonetheless, even if the resultant mixture is a belila ava, one may be lenient and prepare it with a shinnui, because generally speaking, instant food cannot be prepared on Erev Shabbat, as it will be cold and unappetizing by mealtime on Shabbat.  As we have explained in previous shiurim, one should stir the belila with a shinnui, and it is desirable to change the sequence of ingredients. 


When Stirring is Unnecessary


If the instant food consists of a powder which becomes a thick mass on its own after hot water is added — e.g., potato puree — it is questionable whether a shinnui renders the lisha permissible.  The Gemara in Zevachim (94b) discusses sowing flaxseed in water.  In the Gemara, it is explained that there is a prohibition of lash, since the flaxseeds stick to each other.  The Rambam (8:16) rules:


Whoever puts sesame seed, flaxseed and the like in water is liable because of lash, as they mix and adhere to each other.


It would stand to reason that this ruling is based on the view of Rabbi, who believes that the very act of putting flour into water makes one liable because of lash.  According to Rabbi Yosei bar Yehuda, who believes that one is liable only for actual kneading, even one who puts flaxseed in water would not be liable.  However, we have not found in the Gemara or in the writings of the Rishonim that Rabbi Yosei bar Yehuda challenges this law, and the implication is that it applies according to all views.  Similarly, the Rambam and other Rishonim rule in according with the view of Rabbi Yosei bar Yehuda, yet they also rule that one is liable for putting flaxseed into water.  This is also the view of the Shulchan Arukh (340:12).


In light of this, it seems that all agree that if by adding water alone a true mass is created, this constitutes a violation of the melakha of lash.  When one puts flour into water, a true mass is not created; therefore, according to the view of Rabbi Yosei bar Yehuda, one is not liable until one kneads the mixture.  However, putting flaxseed into water creates a fully blended mixture and a true mass, and there is no need for additional kneading or stirring; therefore, this act is viewed as an act of lisha — on a Torah level — according to all views.


This case would seem to be similar to instant foods which do not require stirring to form a mass.  Here too, the very act of adding liquid to the powder creates an agglomerated mass.  As we have said, creating a mass in this way is forbidden by the Torah according to all views.  Does a shinnui help here?


The Gemara does not explicitly address whether, in the case of putting flaxseed into water, a shinnui makes the act permissible.  From a logical point of view, it appears that a shinnui in mixing will certainly not suffice here, because the mass is created before the stirring, and only a shinnui in ingredient sequence would be effective.  As we have seen, this shinnui, which is not a total shinnui, is effective only for a belila rakka, which is rabbinically prohibited, and not for a belila ava, which may not be kneaded by Torah law.  However, is this shinnui effective also according to the view of Rabbi Yosei bar Yehuda (whose view is considered authoritative by the letter of the law)?


In a previous shiur, we saw an argument of the Acharonim as to whether a shinnui in ingredient sequence is effective only according to the view of Rabbi, or even according to the view of Rabbi Yosei bar Yehuda.  According to the view of the Terumat Ha-deshen (Ch. 53) and the Rema (321:16), this shinnui is not effective according to the view of Rabbi Yosei bar Yehuda, and only a shinnui of kneading is effective according to his view.  The Mishna Berura (68) seems to confirm this.  The Shulchan Arukh (321:14), on the other hand, indicates that a shinnui in ingredient sequence is effective even according to the view of Rabbi Yosei bar Yehuda, and this is the view of the Chazon Ish (58:5, s.v. U-mashma).


Yet, it stands to reason that in the case of putting flaxseed into water, all will agree that a shinnui in ingredient sequence would help, even according to the view of Rabbi Yosei bar Yehuda.  Only when the mass is created at the time of kneading is there an argument to say that a shinnui at the stage of adding ingredients is not effective, because this stage is not part of the lisha, and this is what the Terumat Ha-deshen and the Rema maintain.  However, when the mass is created on its own by putting in water, and the very act of adding water makes one liable for lash according to all views, as explained above, it makes sense that Rabbi Yosei bar Yehuda would concede that a shinnui at this stage is effective, because this is a stage which makes one liable for lash.


According to this, one may be lenient and add hot water to a powder which will then form a mass on its own if one changes the ingredient sequence, and on the condition that we are talking about a belila rakka.  This is what Rav Moshe Feinstein (Iggerot Moshe, OC, Vol. IV, Ch. 74, Lash, 12) indicates:[2]


Is it permissible to prepare instant potatoes or instant pudding by a shinnui of putting in the water afterwards and a shinnui of the mixing?


Answer: Instant potatoes are forbidden in any case, but one may prepare instant pudding as a belila rakka if one puts in the water afterwards and mixes it with a shinnui.  For a belila ava, it is forbidden in every way. 


According to this view, one may prepare pudding on Shabbat, even though it forms on its own after the addition of water, on the condition that it will be made as a very fluid pudding, so that it will be considered a belila rakka.  Furthermore, one must alter the sequence of adding ingredients (if one wants to stir, one should stir with a shinnui).


On the other hand, Rav Feinstein forbids preparing potato puree from a powder, since the belila is created on its own without stirring, and this belila is ava.  In this case, a shinnui in the method of mixing will not be effective, since the mass is created before the stirring occurs, and a shinnui of ingredient sequence will not be effective, since this shinnui is not effective for a belila ava.


However, if it is impossible to prepare the puree before Shabbat, and one wants to prepare it on Shabbat itself, (for example, one is stuck for Shabbat in a place with no prepared meals), one should prepare the puree with a lot of water, so that it will be runny and considered a belila rakka.  In this case, one may be lenient on the condition that one puts the water in first and afterwards the powder (the reverse order from the weekday) and if one wants to stir, one should stir with a shinnui, i.e., sheti ve-erev instead of a circular motion. 


Gelatin Desserts


Gelatin desserts would apparently be similar to instant potato puree, in that it hardens on its own and becomes a belila ava, so that it would be forbidden to make them on Shabbat.  This is what the Shevet Ha-levi writes (Vol. VII, Ch. 41).  However, it may be that the case of a gelatin dessert is different, since there is no mass per se (as with pudding); rather the powder dissolves in its entirety and becomes fluid, and after that it congeals on its own, so that there may be no prohibition of lash at all.  This is what the Orechot Shabbat (Ch. 6, n. 83) writes; nevertheless, he indicates that it should be forbidden because of uvdin de-chol (a weekday practice — something inappropriate for Shabbat but not falling under the rubric of any particular melakha).  Practically, allowing this is very questionable, and therefore one should not make gelatin desserts on Shabbat.  However, in a case of great need, if one prepares the gelatin desserts with a very soft consistency and also alters the sequence of ingredients, there are opinions on which one may rely in order to prepare it.


Baby Food


When one prepares instant cereal for infants, one is often dealing with a powder which forms a mass on its own, and if so one may prepare it as a belila rakka (pourable) if one changes the ingredient sequence, and this is the preferable practice.  However, many times we are dealing with a granular substance which requires additional stirring; therefore, the law will be that of a regular belila: one may prepare it for an infant with a shinnui even if the belila is ava (as we explained previously).


When one is preparing formula for a baby — i.e., powdered milk — generally it is very fluid (even if it is a bit thicker than coffee or chocolate milk).  Therefore, it does not even rise to the level of a belila rakka, and one may prepare it on Shabbat normally, without any shinnui (one should first put in the hot water and afterwards the powder, to avoid a concern of bishul).  If the liquid is more viscous and defined as a belila rakka, one should prepare it with a shinnui.[3]


This is our final shiur on lash.  The next melakha, bishul, has been dealt with at length by HaRav Baruch Gigi in his 27-part “Hilkhot Shabbat” series (available at  We will resume our course of study by going back to the beginning — to the melakha of zoreia (sowing).



Translated by Rav Yoseif Bloch

[1]     As we have explained above, according to the Sefardim one shinnui suffices — in either ingredient sequence or mixing, while according to the Ashkenazim, one should first change both the ingredient sequence and the mixing.  However, in cases where this is difficult or for a very thin mixture, a shinnui in ingredient sequence suffices. 

[2]     See also Shevet Ha-levi, Vol. VII, Ch. 105; Vol. IX, Ch. 73.  See Shalmei Yehonatan, 321:16, 55 as well. 

[3]     When there is a doubt as to whether a mixture is a true liquid or a belila rakka, it is appropriate to change the ingredient sequence; however, if this proves to be difficult, one may be lenient, as we have explained previously.