WHEN I PREPARE NESCAFE INSTANT COFFEE ON SHABBOS, I POUR HOT WATER FROM AN URN DIRECTLY INTO A CUP, AND THEN ADD THE COFFEE. I’VE TAKEN A LIKING TO NESCAFE VANILLA AS WELL AS NESCAFE HAZELNUT. DOES THE PRESENCE OF THE FLAVOR COMPLICATE MATTERS?
It is permitted to cook on Shabbos a dry food that, before Shabbos, has already been fully cooked, provided that the additional cooking on Shabbos doesn’t further develop the taste of the cooked food (O.C. 318, 4-5, and see Taz s.k. 6).
TRADITIONAL NESCAFE – like any other kind of instant coffee – is made from coffee grounds that have already been roasted and then brewed. Nescafe is then dried through a process called freeze-drying. When the consumer pours hot water over the instant coffee powder, he is essentially rehydrating already fully cooked coffee. It is therefore permitted to prepare instant coffee using hot water on Shabbos.
Igeros Moshe (O.C. 4, 74:16) indicates that, strictly speaking, it is permitted to pour hot water directly onto instant coffee (though he writes that he himself is machmir to use a kli shlishi). Minchas Yitzchak (1,55) notes that since Nescafe dissolves when hot water is poured onto it, it is meritorious to view it not as a dry food, but rather as a cold liquid, which is subject to the concern of bishul achar bishul (Mishna Berurah, 318, 71). However, since reheating liquid in a kli sheini is permitted, one may add Nescafe to a kli sheini (Shulchan Aruch haRav, 318, 12).
As a matter of policy, OU caterers are instructed to transfer hot water to a kli sheini before adding instant coffee powder.
Ground coffee, which is made from roasted coffee beans but has not been previously brewed, may not be prepared on Shabbos even in a kli sheini. This is because foods which are kali habishul (easily cooked) will be cooked in a kli sheini so long as it is yad soledes bo. Many poskim rule that we are required to view all foods as kali habishul unless designated by the Gemara or poskim otherwise (see Mishnah Berurah, 318, 42). It is worth noting that Rav Ovadiah Yosef zt”l (Yebiah Omer O.C. 8:35) ruled that roasted coffee beans are considered already fully cooked. He agreed, however, that Ashkenazim may not brew ground coffee in a kli sheini on Shabbos, since the Rema is machmir for the opinion that yesh bishul achar afiya even in a kli sheini (318, 5).
FLAVORED NESCAFE TASTER’S CHOICE – In recent years Nestle has introduced two flavored Nescafe products, Vanilla and Hazelnut.
If these products were simply the result of adding vanilla extract, or hazelnut oil, to Nescafe instant coffee, there would be reason to think that a person should view the product as kali habishul. In the traditional process for extracting vanilla, an alcohol and water mixture colates through macerated, or chopped up, vanilla beans, stripping the vanilla beans of their flavor (after percolating through the vanilla beans once, the liquid is pumped back to the top of the tank and percolates again, each time becoming richer in vanilla flavor). The temperature of the solution used to extract the vanilla is 120°F (Igeros Moshe (O.C. 4, 74, 3) writes that yad soledes bo, l’chumra, is 160˚ F) and further processing steps simply cool down the product. In some cases vanilla extract is performed at ambient temperatures. Similarly, hazelnut oil is not necessarily heated in the extraction process.
There is, however, much more that goes into these products than the addition of the flavor to the instant coffee. Each of the products contains “natural and artificial flavor”, as indicated on their ingredients labels, and which, in each case, refers to a flavor compound consisting of several dozen flavor chemicals. Each component is carefully chosen by a flavorist to provide the rich, well-rounded, and consistent flavor profile we find in each of these products. More to the point, however, Nestle uses a very specific form of the natural and artificial flavor, the result of a process called encapsulation.
In this process a flavor compound is embedded in a protective coating. In the case of instant coffee, the flavor may be embedded in a material soluble in heat and water. The coating stabilizes, or preserves, the flavor compound until the magical moment when the consumer pours hot water onto the instant coffee, at which point the protective coating dissolves and releases the desired flavor.
Encapsulation occurs in a large, very hot chamber called a spray drier. The liquid product, mixed with a carrier (the protective barrier) is pumped through a small nozzle into this chamber, at which point the water component instantly vaporizes and the solid constituents, the carrier with the flavor, fall to the bottom, where they are recovered.
In order for this process to work efficiently, the liquid mixture must be preheated before being pumped to the spray-drier. The liquid is cooked to temperatures that exceed yad soledes bo, with the result that the natural and artificial flavor is mevushal. 
Also present in the flavored products is maltodextrin, a partially modified starch. The modification process involves a heating step that constitutes a proper bishul.
Two final ingredients identified on the label – caramel color and acesulfame potassium – are also heat-treated, but to protect the confidentiality of the process the methods cannot be disclosed here.
In sum, if a person prepares Nescafe and uses a kli sheini, he can continue doing so using the Nescafe flavored products as well.
by Rabbi Gavriel Price, RC, Ingredient Registry
The Halachic content of this article was edited by Rabbi Eli Gersten, RC Recorder of OU Psak and Policy
 Most instant coffees are spray-dried (in contrast to freeze-dried, the method used for
Nescafe). Rav Eliashiv zt”l (Meor Shabbos III, note 76) notes that the spray-drying component
of instant coffee may be considered an יופא and therefore, ideally, a person should be con-
cerned for bishul achar afiya achar bishul and use a kli shlishi. This concern would presumably
apply in this case as well. See also Rav Wosner (Kovetz Mibeis Yoel 8, Page 166). The OU poskim,
however, point out that the spray-drying process does not change a product’s taste and
therefore should be considered only mevushal (see also Taz, 318, 6).