Question
When shopping for cheese, I often notice that some products carry a regular kosher certification, while others are labeled Mehadrin, with both labeled as Chalav Yisrael. I was told that both are kosher, but that Mehadrin cheese follows a stricter standard. What exactly is the difference? If both are Chalav Yisrael how can one be more Kosher than the other?
Answer
The primary difference between many regular kosher cheeses and Mehadrin cheeses is that Mehadrin hashgachos often require that the Mashgiach himself place the rennet (curdling agent) into the milk, while regular kosher certifications may suffice with Jewish supervision of the cheese-making process. This dispute is rooted in a major halachic disagreement between the Rama and the Shach regarding what is required to avoid the prohibition of Gevinas Akum (gentile cheese).
Accordingly, many Mehadrin certifications are stringent to satisfy the opinion of the Shach, while standard kosher certifications generally rely on the ruling of the Rama and many other Poskim.
Explanation
The Original Decree of Gevinas Akum: Chazal decreed that cheese made by a gentile is forbidden, even if the milk itself is kosher. The classic concern was that gentile cheesemakers would use non-kosher animal stomachs as the catalyst that turns milk into cheese. Since the catalyst creates the cheese, the Sages prohibited such cheese. Furthermore, the Michaber rules that even if the gentile used a kosher catalyst, the cheese remains forbidden because the Sages enacted a broad decree and did not distinguish between different methods of production.
The Opinion of the Rama: The Rama records the accepted Ashkenazic custom that if a Jew supervises the cheese-making process, and sees the gentile inserting the Kosher rennet into the milk, then the cheese is permitted. According to this approach, active Jewish supervision of the manufacturing process is sufficient to classify the cheese as kosher. This became the accepted practice in Ashkenazic communities and is the basis for many standard kosher cheese certifications today.
The Opinion of the Shach: The Shach strongly disagrees. He argues that supervision alone does not help. Since Chazal prohibited gentile cheese, merely watching the process is insufficient. Rather, the cheese must actually be made by a Jew, and this is accomplished by having the Jew place the catalyst into the milk. According to the Shach:
- A gentile adding the rennet while the Jew merely supervises is insufficient.
- The Jew must actively participate in the cheese-making process by adding the catalyst.
What Is Rennet? Rennet is the ingredient that transforms liquid milk into solid cheese. Without the rennet, the milk remains milk. Once the rennet is added, the milk begins the curdling process and becomes cheese. Since this is the critical act that creates the cheese, the Shach requires that this act be performed by a Jew.
The Practical Difference Between Regular Kosher and Mehadrin: This is where the practical difference often emerges. A regular kosher cheese may be produced in a facility where:
- The Mashgiach supervises the process.
- The gentile worker adds the rennet.
- The certification relies on the ruling of the Rama.
A Mehadrin cheese will often require:
- A full-time Mashgiach present.
- The Mashgiach himself adding the rennet every time cheese is produced.
- Compliance with the stricter opinion of the Shach.
Thus, both products may be fully kosher, but the Mehadrin product follows an additional level of stringency.
Is the Cheese Factory Owned by a Jew? The Shach notes an important qualification in his stringency. If the milk belongs to a Jew and the cheese is being produced on behalf of a Jew, then according to all opinions a gentile may perform the process when a kosher catalyst is used. Therefore, the ownership structure of the plant may also affect the practical halacha.
The Ruling of the Alter Rebbe: The Alter Rebbe appears to rule leniently like the Rama that supervised cheese is permitted, even if the gentile inserted the catalyst. Nevertheless, many Mehadrin hashgachos choose to be stringent for the opinion of the Shach and require Jewish insertion of the rennet.
Practical Summary
| Level | What Happens |
| Regular Kosher Cheese | Jewish supervision of production; certification often relies on the Rama. |
| Mehadrin Cheese | The Mashgiach personally adds the rennet in order to satisfy the opinion of the Shach. |
| Jewish-Owned Production | Greater leniency exists according to all opinions when the milk belongs to a Jew. |
Sources
Hakashrus 8:20
The prohibition of Gevinas Akum even when made from kosher milk: Michaber Y.D. 115:2; Shach 115:19; Taz 115:9-10; Avodah Zarah 29b
The ruling of the Rama permitting supervised cheese: Rama Y.D. 115:2; Admur 307:38; Toras Chatas 81:1; Darkei Moshe 115:2; Minchas Yaakov 81:3; Peri Toar 115:3; Noda Beyehuda Tinyana O.C. 37; Tiferes Limoshe; Pischeiy Teshuvah 115:6; Aruch Hashulchan Y.D. 115:19; Igros Moshe YD 3:16
The ruling of the Shach requiring the Jew to place the catalyst into the milk if the milk is owned by a gentile: Shach Y.D. 115:20; Taz 115:11; Peri Chadash 115:15; Biur HaGra Y.D. 115:15; Chochmas Adam 67:7
The ruling of the Alter Rebbe permitting supervised cheese even when the gentile inserted the catalyst: Admur 307:38