The hallowed cornerstone of kashrus. בחלב אמו אל תבשל, Do not eat a goat in the milk of its mother. The Torah repeats this prohibition מצות לא עשה three times,1 instructing us that we must not eat, cook or derive benefit from a combination of milk and meat. To distance ourselves from an inadvertent mistake, safeguards have been instituted and implemented by Chazal to preserve the integrity of the essential מצות לא עשה.
To this end, every kosher kitchen has two separate sets of pots, pans, cutlery and dishes. Similarly, if two people are eating together at the same table, one eating meat and the other eating dairy, the Shulchan Aruch instructs us to make a distinguishing separation between the two friends to avoid an inadvertent nibble.2 Moreover, the Shulchan Aruch also instructs us to wait after eating meat before eating dairy or drinking milk.3 There are a number of reasons given for this time separation, either the time it takes to digest meat or to neutralize any lingering taste that may remain in one’s mouth after eating fleishig. There is also a halachic dichotomy as to how long one has to wait: 6 hours, 3 hours or 1 hour. Regardless of one’s minhag, waiting between meat and milk is a halachic system already in place.
Does eating meat after dairy also warrant waiting? The halacha states that one who has just partaken of a dairy meal and wants to eat meat need only eat something pareve that is hard, such as a cracker, or drink something pareve, such as water, and wash one’s hands, this is known as קינוח והדחה.4
The only exception is hard cheese.5
In order to understand that exception, we first need to understand the rule; in order to understand the rule, we need to understand what constitutes cheese. Cheese is defined as a product that is created through a process of pressing or compressing coagulated curds into cheese. Essentially, all cheese – including soft cheese or “semi-solid” cheese – is the coagulation of milk solids through either acidification, coagulation or a combination of the two. The combination results in a coagulation of milk proteins, forming a gelatinous web that can be cut into curd blocks or pieces, separated from liquid whey and then gathered, processed, cooked and/or salted for further processing6 and aging. All cheese combines the same three basic ingredients: milk, bacterial culture and rennet. There are many types and styles of cheese. Some cheeses are soft and spreadable, i.e., cream cheese and mascarpone, which are called soft cheeses and do not fall into the traditional definition of cheese. There are cheeses that use a mold to transform the cheese, such as brie or camembert, which are categorized as semi-solid cheeses.
The generic term “cheese” doesn’t do justice to the artesan nature of this unique creation. If you break down cheese into small categories, there are hundreds of varieties of cheese ranging from a typical soft, soft hardened, slicing cheese to mild, ripened, hard … and variations in between.7
The kosher cheese assortments that we typically see on the shelf which include cheddar, muenster and mozzarella are produced in large cheese plants in an industrial setting, not in a small artesan textbook description of a cheese plant. Today’s popular sliced cheeses that are sold in the supermarket can and are produced in a day, not in weeks or months as cheese articles lead us to believe. Yet, there is a large selection of cheeses that are not typically seen on the supermarket shelf that are aged for long periods of time, such as Asiago and Parmegiano Reggiano that don’t find their way to the supermarket for 1-2 years. These varieties are classified as hard cheeses. Regarding the wait between dairy and meat, the Rema is as lenient about a quick החדהו חוניק as the Bais Yosef, save for one exception: hard cheese.
How does halacha quantify hard cheese? It is not simple. The Shach defines hard cheese by two criteria: Cheese that is aged for six months or cheese that has natural holes in it, known in the cheese world as Emmental (Swiss cheese). The Shach and Taz8 9 state that one must wait as long as one waits between meat and milk when first eating hard cheese followed by meat.
There is much conjecture amongst the Poskim as to the implication of the Shach’s six month criteria. Some Poskim go as far as to consider any cheese that slices as hard cheese. Some consider cheese that has been left to dry and harden as hard cheese. Some say cheese left on the shelf for six months is a hard cheese. Analyzing the Shach carefully in the context of the science of aged cheese, six months is not an absolute time frame. The six month criteria is as the Shach states, a result of aging cheese to achieve a desired result.
What happens during the aging process of cheese? According to cheese experts, during aging the moisture content of the cheese continues to decrease and the bacteria which ripens the cheese gives it a stronger flavor as it continues to age. As the moisture decreases the flavor increases and, as a result, the cheese hardens. The king of hard cheese, Parmigiano Reggiano, achieves its unique flavor profile after 24 months!10 18 months is the youngest that the Parmigiano Reggiano can be sold.
Of course, these flavorful hard cheeses have one common quality. After being aged for long periods of time they can’t be sliced, only grated. Furthermore, these hard cheeses have so much increased flavor, “a small sprinkle is powerful enough to season an entire dish.” These hard cheeses are categorized as grating cheeses – not crumbled, sliced, or spread – but grated. This is precisely how the Gadol Hador, Hagaon Harav Aharon Kotler, zt”l, understood the Shach’s halachic definition of hard cheese as corroborated by contemporary cheese experts. This is the STAR-K hard cheese policy according to the opinion of STAR-K’s Rabbinic Administrator, HaRav Moshe Heinemann, shlit”a.
Futhermore, the Shach continues and says that fatty cheese is not a determining criteria for hard cheese, as posited by others. Interestingly, in discussion with world famous Italian cheesemaker Raffaele Cioffi, whose family has been producing artesan Italian cheeses for over 160 years, he stated that in order to make Parmigiano the milk used must be skim milk with the fat removed!
Although not all hard cheeses are aged for 24 months, the grating criteria also applies to cheeses that are aged less than two years. For example, sharp cheddar cheese that is aged to the point it cannot be sliced – only grated – is considered a halachic hard cheese. The cheddar we purchase in the kosher cheese section that is pre-sliced or sold in sticks is mild cheddar. חוניק and החדה would be sufficient between mild cheddar and meat.
Does hard cheese that has melted retain the halachic hard cheese criteria? It is the opinion of HaRav Moshe Heinemann, shlit”a, that it remains “hard cheese”. As Raffaele Cioffi discussed, in Italy the qualities of Parmesan cheese that they use is only a sprinkle of the cheese to season a famous Parmesan flavored soup, where the cheese blends ever so smoothingly in the soup and the taste is outstanding.
Although defining hard cheese halachically is up for discussion, cheesemakers certainly agree that like good wine hard cheese improves with age.

1. שמות כ”ג” י”ט, שמות ל”ד: כ”ו. דברים י”ד: כ”א
2. יורה דעה פ”ח: א’,ב’
3. יור”ד פ”ט: א’
4. יור”ד פ”ט: ב’
5. רמ”א שם
6. Cheese 10: The Hard Facts
8. ש”ך ט”ו
9. ט”ז ד’
10. Cheese 10: The Hard Facts