Is it permitted to spray whipped cream from a can on Shabbos?
Some kosher products, such as whipped cream, come in spray cans which bear a warning to consult a Rav before using it on Shabbos. One issue relevant to whipped cream may be creating a specialty shape on Shabbos, which violates the melachah of boneh (construction).
Even if one doesn’t create a specific shape, there remains the question of whether using a spray can on Shabbos is permissible—or does it violate the melachah of zoreh (winnowing – employing the force of the wind)? According to the consensus of poskim, this isn’t an issue due to the mechanics of the cans, since the spray is expelled due to internal pressure and is therefore not comparable to the force of wind.
On the other hand, a pump spray, such as a Windex bottle—which uses a venturi tube system— might be considered zoreh according to some opinions, because it’s akin to using the force of wind, which is not permissible on Shabbos.
While some authorities prohibit spraying whipped cream from a canister on Shabbos due to the issur of molid (creating a new substance), since the cream changes temporarily from a liquid to foam, there are many grounds for leniency.