Kashrut

One may not cook on Shabbos. This includes boiling, baking, roasting and frying. However we should make an effort to have hot food and drink as this is an honour for Shabbos.

We may have food that was heated before Shabbos and kept warm.

So it may be heated in an oven and then the oven can be switched off before Shabbos and the food kept warm until it is time to eat.

Food can also be kept warm on a hot tray. It is best to cover the temperature knob as a reminder not to turn it up or down on Shabbos.

Solid food that is hot can cook other food even when it is not on a heat source. So we need to be careful not to put lemon juice on to hot salmon as the salmon will cook the lemon juice.

Water from an urn may not be poured directly on to a teabag, coffee, milk or sugar as this counts as cooking.

To make a cup of tea or coffee, one should pour the water from the urn into a cup, then pour the water into a second cup, then add the tea, milk etc to the second cup.

One should also be careful that there is no room temperature water in the cup which receives the boiling water from the urn, as the water from the urn will cook the water in the cup.

If food is dry and fully cooked, some permit one to place it on a hot tray on Shabbos so that it heats up. If there is a knob that regulates the temperature that should be covered (e,g. with a piece of foil).

If there is so much solid fat on the food that it will melt and form a pool of liquid, one should not heat the food unless one would be happy to eat the fat in its congealed state.

If the food has a significant amount of liquid (e.g. goulash, soup) one may not heat it up on a hot tray even if it is fully cooked already, because heating a liquid up from room temperature is considered cooking even if the liquid has been cooked before.

One may not use on Shabbos an implement that is designed for grinding and mashing, such as a grater or a masher.

Grinding and mashing are forbidden for things that grow from the ground.

There are a number of exceptions to this rule:

• If the food is cooked so much or is so ripe that when one pulls at it falls apart, then one may mash or grind it in the usual way.
• If the food is chopped into pieces that are larger than usual (i.e. not as small as one can chop them) this is permitted.
• If the food is chopped or mashed for immediate consumption, this could be considered as part of the eating process and not a separate standalone activity. If one is preparing for a child or someone who is unwell, this leniency can be used.
• The prohibition only applies to things that grown on the ground or a tree. So eggs and fish may be ground or mashed as finely as one likes; however one may not use an implement designed for this purpose.

Kneading solids and liquids into a thick mixture that cannot be poured is forbidden by Torah law on Shabbos. If the mixture is easily poured, mixing it is forbidden by the rabbis.

If one is making

a thin mixture for a little child or an elderly person,

or

a thick mixture that cannot be made before Shabbos because it will spoil,

one may make the mixture on Shabbos by using two unusual actions:

• the ingredients should be put in the bowl in an unusual order

and

• the ingredients should be mixed with a criss-cross rather than a circular action.

There are rules about sorting a mix of things on Shabbos.

Different types of things are considered mixed if:

• they are difficult to separate (e.g. laundry in a basket)
• they are attached to each other (e.g. fish attached to bones)

OR there are small solids in a liquid

We may only take:

1. what we want
2. without using an implement
3. for immediate use

So…

• we may not pick bad grapes off a bunch since this is picking out what we don’t want and we may only pick out what we want.
• we may not use a sieve or a slotted spoon to scoop peas out of their water as this is use of an implement designed for separating.
• we may not pick out cutlery from a mix and use it to set a table for use the next day.
• we may not pick a bone out of a piece of meat or fish.

The rules of sorting do not apply to food in one’s mouth as this is considered part of eating. So if someone is eating meat and finds a bone in it, they may take the bone out of their mouth and leave the meat in their mouth.

One may take the bad from the good for immediate use without using an implement designed for this if there is no other way of getting to what one wants. This is considered part of the normal use of what one wants.

So…

• one may peel a banana or shell a boiled egg by hand.
• one may peel carrots with a knife as a knife is not considered designed for this.

However one may not use a peeler to peel a carrot.  

We may not normally squeeze juice out of a fruit on Shabbos.

When it is very common to squeeze a fruit, this is forbidden by Torah law. This applies to grapes and olives which are often cultivated specifically for their juice/oil.

The rabbis forbade juice that came from olives and grapes on Shabbos even if it came out by itself or by accident.

Other fruits may not be squeezed on Shabbos, but if juice came out of them by itself or accidentally, one may drink it. So if someone eats a fruit salad with a spoon and some juice is left over, they may have that juice.

Generally speaking, we may take something solid out of the freezer to defrost it, and we may put something into the freezer to freeze it.

It is preferable not to freeze water into ice on Shabbos because this is considered like making a new thing which the rabbis did not allow on Shabbos,. However in a case of need this is permitted because freeing liquid is a temporary change which only endures as long as the ice is in the freezer.

It is better not to allow ice to melt by itself, but it may be put into liquid where its melting will not be noticeable.

However ice cream may be taken out of the freezer even if we know it will melt, because melted ice cream has the same function as frozen ice cream so the change if state is not considered important.

We may only have wine and grape juice that have been made by Jews. If a non-Jew even just moves them in an unsealed bottle they become non-kosher.

If the wine or grape juice is boiled, these restrictions no longer apply. This is known as yayin mevushal or pasteurised wine.

We may drink wine or grape juice with our non-Jewish friends if it is kosher and only handled by Jews, or if it is yayin mevushal.

Likewise, we may not eat bread baked by non-Jews in their homes even if all the ingredients and the equipment are kosher. However, if all the ingredients and processes are supervised and known to be kosher and there is no Jewish baked bread available, we may eat bread baked by a non-Jew in a commercial bakery.

Likewise, we may not eat “prestigious” foods cooked entirely by a non-Jew. However, if a Jewish person turned on the heat process this is permitted. Also, if the food was cooked by a Jew and then frozen, a non-Jew may defrost and reheat it for the Jew to eat.

Jewish law specifies that not only may we not eat or drink non-kosher things; we may not even eat kosher food/drink that has the taste of non-kosher things in them. This is derived from verses in the Torah.

Taste can be transferred through heat that is sufficient to make one pull one’s hand away instinctively defined in modern times as 43^oC. So for instance if a pot is used to cook meat, the taste of the meat goes into the walls of the pot. If that same pot is then used to cook milk, the taste of the meat will come out of the pot into the milk and make it non-kosher. This applies even if the pot was cleaned between uses.

If 24 hours pass between the first and second cooking, then the taste is no longer considered a problem. However, we should not plan to rely on this. Only if a mistake actually happened will we use this rule to say that the milk is kosher if the pot was used to boil milk more than 24 hours after it was used to cook meat.

Rabbi Moshe Feinstein ruled that we may cook meaty in a milky oven and vice versa provided that the lid stays on until the pot is completely out of the oven. Rabbi Shlomo Zalman Auerbach did not permit this.

Some are strict to have separate stoves for meaty and milky, or separate pan supports.

However this stricture is generally only observed for Pesach. For the rest of the year, it is common practice to use the same stove top for meaty and milky cooking. We can assume that food residue is probably burned to ash on the pan support and edible dry residue will not transmit its taste into the food in the pan.  Likewise, if any milk or meat lands on the pan supports it will probably not get transmitted to the pan on the support.

If one sees meaty food/liquid on the stove top, pan supports or burners, one should clean it off before cooking milk or something milky, and vice versa.

Rabbo Moshe Feinstein recommends turning on the heat for a little while when going from cooking meaty to milky and vice versa so that any food remnants are burned to ash.

We normally take a strict view to require a stove top that has been used for cooking non-kosher food to be kashered first.

For a detailed explanation of this law, see here: https://rabbikaganoff.com/is-my-stove-kosher/

This only starts to be a problem when the water is yad soledes bo (hot enough that when we hold it, our hand instinctively pulls away – 43^oC).

It also only starts to be a problem if the mix happened while the water was being poured into the bowl. If, on the other hand, the water was poured into the bowl and only then the mix took place, there is nothing to worry about because once the water is held in the bowl it is deemed unable to mix tastes.

If the water was yad soledes bo and poured on to the mix of utensils when they were already in the bowl, this means that taste can transfer from one to the other. However, if the problematic utensil had not been used for actual hot meat or milk in the last twenty-four hours, it can’t transfer taste across. It can only absorb taste and only it needs to be kashered.

Furthermore, if there is more than sixty times the volume of the offending utensil in the rest of the utensils and the water, then the taste coming form the problematic utensil is considered to be cancelled and only it needs to be kashered. This principle also applies to an offending utensil in a dishwasher.

If a sharp tasting food such as an onion is cut with a milky knife, then it draws the taste of the knife into itself even if the knife had not been used in the last twenty-four hours.

This means that if an onion is cut with both a milky knife and a meaty knife, it is non-kosher.

If a taste goes through two stages of transmission and is still not forbidden, it can be ignored. But we don’t rely on this in the first instance.

So for instance if pasta was cooked in a pot that had recently been used to cook meat, then the pasta is meaty. If one then accidentally cooked the pasta with cheese or in a milky pot, it may still be eaten.

An unhatched bird is not kosher. As a bloodspot may be a baby bird, we don’t eat free range eggs with bloodspots. However a barn egg just has to have the egg removed.

White eggs are easily checked for bloodspots so they are normally free of bloodspots.

https://www.kosher.org.uk/sites/default/files/checkingforbugs_klbd_-_a3_poster_0.pdf