DIY: Traditional Rennet

Warning: This post has a few photos that might bother some – internal organs just after being harvested. 

Although I’m a vegetarian in all other respects, I do eat classic cheeses such as Parmigiano Regianno and Roquefort, all of which are made with traditional rennet. I also butcher animals on our farm to feed my family. Included in that menu is the occasional goat.

Cheesemaking is a huge part of my life. I’m inquisitive nature and always wanting to learn more about all aspects of cheesemaking. One of those aspects that I had no experience with is the harvesting of a kid and production of natural rennet.

An opportunity presented itself while I was teaching a week long goat care class here at our farm and the attendees expressed an interest in learning how to butcher a goat. Athough slaughter and butchering are a very somber, intense, and private experience for me, I believe strongly in helping others learn not only how to do it properly, but that it can be a beautiful and educational experience as well.  The saying “every animal deserves a good life, a good death, a good butcher, and a good chef” is one of my favorites. So we selected a candidate, a two week old buckling. Not only would the students learn to butcher, but I would harvest the abomasum (the fourth stomach from which traditional rennet is made), our intern Amanda would tan the hide, and the entire

Baby ruminants are truly the first cheesemakers! These cheese curds were in the abomassum of a two week old kid.

Baby ruminants are truly the first cheesemakers! These cheese curds were in the abomassum of a two week old kid.

class would feast on roasted, suckling kid for our final meal.

 

I had read several accounts of how to harvest and make kid, calf, and lamb rennet. All of them varied and all of them stated that the curing time for the organ was anywhere from 6 months to a year. Hmm, why would that be, I wondered? The kid makes cheese curds immediately in its stomach, so it wouldn’t be for the sake of effectiveness. I believe now, but haven’t confirmed, that it might have to do with safety. The long pickling time might be to anticipate parasites or pathogens present in the organ. One of the students in the class told me that she had a Greek cheesemaking friend and would find out what he knew. Fortunately his recipe for kid rennet took only a few days of processing. The resulting rennet works beautifully!

I have made two varieties of our cheeses using the same batch to make one wheel using the homemade rennet and the rest of the batch with what I usually use. This way they will age side by side and any flavor differences will not be due to different milk or cultures. I’m still waiting for the cheeses I’ve made with it to age, but will report back to you on the flavor comparison. One of the cheese types I made usually uses purchased traditional rennet and the other microbial. So it should be quite interesting to compare. I can’t wait!

The abomasum is on the left in this image.  The esophagus can be seen at the bottom and the intestines at the top right

The abomasum is on the left in this image. The esophagus can be seen at the bottom and the intestines at the top right

The inside of the abomasum is covered with gentle folds of skin

The inside of the abomasum is covered with gentle folds of skin

 

 

 

 

 

 

 

 

 

 

Instructions for making kid, lamb, or calf rennet

  1. Harvest the abomasum of a kid, calf, or lamb under two weeks of age is ideal
  2. Rinse with non-chlorinated water, but don’t scrub
  3. Weigh the abomasum and place in jar.
  4. Add 12-15% salt and enough water to cover
  5. Let set at 65-70F for 24-36 hours
  6. Remove from the salt brine and shake off.
  7. Hang to dry in a cool room (no warmer than 70F) and dry until hard – depending on size 1-2 weeks.
  8. Weigh then cut into thin strips and place in food processor or run through a meat grinder.
  9. Slowly add 8 parts non-chlorinated water and process or use mortar to grind into a slurry or paste.
  10. Pour through a fine cloth, pressing with a spoon to extract as much liquid as possible.
  11. Add 4-5% salt by weight
  12. Keep in fridge.
  13. Use about ½ tsp (2.5 ml) per gallon (4L) of milk (you may have to adjust amount,  milk at 95F should coagulate within 10 min.)
  14. Lasts about six months in fridge.
The abomasum after drying

The abomasum after drying

Straining the rennet paste and brine after processing in food processor

Straining the rennet paste and brine after processing in food processor

During storage in the fridge, the whitish portion separates quickly from the salt water. I’m gently agitating mine periodically and for sure right before using. When used at the recommended ½ tsp (2.5 ml) per gallon (4L) of milk, our milk flocculates in under 10 minutes. So likely a bit less of the mixture is needed. So far, the strength hasn’t changed, but it’s only been six weeks since it was harvested and the processing begun. The strength could be checked before use using the steps in my book, Mastering Artisan Cheesemaking, for testing rennet (page 47) to better calculate the dosage before using.

The kid I harvested was exactly two weeks old and hadn’t yet started to chew his cud. This is ideal, however younger would mean an even higher proportion of chymosin to pepsin (the best natural rennets have at least 95% chymosin). Older animals will have increasing amounts of pepsin that will still coagulate milk, but can lead to bitterness in aged cheeses. Our kid was half Nigerian Dwarf and half Lamancha, so not a very large animal. The abomasum yielded about ½ to ¾ of rennet liquid after processing (I forgot t.o measure it before I used some!)

The Greek cheesemaker, who makes barrel aged feta in Greece and who now uses industrially produced kid rennet, says his cheese hasn’t been as good since he switched. It’s a shame when concerns over food safety also remove aesthetic diversity and opportunities for cheesemakers to craft unique products.  I’m actually not sure what would be involved to legally be able to use “small batch” rennet. Certainly the animal would have to be slaughtered at a USDA facility, but I imagine the process steps would also have to take place in an inspected facility with a meat processing license. Oh well, that doesn’t have to stop any of you from trying this at home!

I recommend Adam Danforth’s book Butchering for an even more in depth, artisan approach to harvesting meat.

 

Early Release Signed Books

PrintHot off the press, I have 100 copies of my new book available now! (Before the official release date March 2016). If you would like to purchase a signed copy I can mail it to you or as a gift to someone else. The cover price is 29.95. I will ship it priority mail for 35.00.  Let me know who to sign the book for and if you want a gift note included.

Book details: Full color, 151 pages, a Mother Earth News Wiser Living recommended book, published by New Society Publishers

In the book I take the approach of teaching cheesemaking as organically progressing lessons – each cheese recipe adds a layer of information, technique, and ingredients. By the time you are through, you should truly understand how to make almost any cheese, and be ready to move on to the deeper science contained in my previous book, Mastering Artisan Cheesemaking (Chelsea Green Publishing).

You can pay via Paypal or check.
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Disbudding – Using Sedation

In the archives you’ll find my article on the Dehorning Dilemma . Because I seem to like inspiring a bit of controversy, here is a video and instruction on how producers can sedate their kids (or calves) and disbud while the animal is semi-conscious. This drug also provides pain control (analgesia).  While some of you may wonder what could be controversial about pain control when performing painful procedures on animals, I have already come under a bit of criticism mostly from professionals who seem concerned that farmers can’t learn how to do this safely and animals will die. I, on the other hand, believe that most of us have the capacity to learn and deserve these options.

Burrata – Forming the Dumplings

As an augmentation to the article I wrote for the summer culture the word on cheese magazine http://culturecheesemag.com/diy/beautiful-homemade-burrata , here are step by step photos of how to make burrata sachets, dumplings, packets or whatever you want to call them!

When the mozzarella texture is just right, you are ready to form the outside

When the mozzarella texture is just right, you are ready to form the outside

Place the ball on a plate and gently flatten it with your fingers, making it as even as possible

Place the ball on a plate and gently flatten it with your fingers, making it as even as possible

Place a well packed dollop of the ricotta and butter mixture in the center

Place a well packed dollop of the ricotta and butter mixture in the center

Gather two sides together in the middle, overlapping and press them together. Gather the other two sides, squeezing closed any openings, and overlap in the center.

Gather two sides together in the middle, overlapping and press them together. Gather the other two sides, squeezing closed any openings, and overlap in the center.

Place the closed packet on the ladle, with the overlapped edges down and immerse the bottom into the hot whey for a few moments, this seals the packet

Place the closed packet on the ladle, with the overlapped edges down and immerse the bottom into the hot whey for a few moments, this seals the packet

Serve immediately or cool in bowl of cold water then wrap and chill. Best right away, though!

Serve immediately or cool in bowl of cold water then wrap and chill. Best right away, though!

Aging Cheese on Wood Shelves and Food Safety – a Non-Issue

Wood Shelves

Don’t be afraid!

As a person who tends to want to follow rules, it is sad to be reminded that a good portion of food production regulations have little to do with actual food safety, rather they are the result of a ponderous, rigid system that steam rolls forward, sometimes based more on the ease of generalizing rather than the complexity of reality. The FDA has never liked wood shelves, especially when you sit food, in this case naturally rinded cheese, directly on its porous surface. Wood does not fit their Good Manufacturing Practice (GMP) model for a cleanable surface. While wood aging shelves have technically never been okay with the FDA, they have until now been mostly ignored and the decision to allow them been left to individual states .In many” big cheese” states, the regulators defer to the scientific knowledge of the leading expert within each state. For example, in both Oregon and Wisconsin (where at least 30 million pounds of cheese is aged on wood each year) the departments of agriculture have an official stance of “no wood shelves”. But in both states if a cheesemaker gets a thumbs up from the academic expert regarding their maintenance protocol for the shelves, then they have been allowed.

Isn’t that sensible? Did you hear me mention the words “scientific knowledge”? Let’s review what is well researched and known about wood shelves. (I’ll give you some references at the end of this post). Guess how many outbreaks of food borne illness they have been implicated in since the dawn of cheesemaking? Zero. This doesn’t mean that pathogens can’t exist on a wood shelf. If a cheese is contaminated and the wood poorly cared for, it will pass it to the shelf, no matter what material it is made from. Contamination of any aging shelf can happen when poor practices occur at any stage of cheese production, but it is not any more likely when wood is used. Bottom line.

Pros and Cons

So why do cheesemakers and affinuers (the folks that age cheese) love wood shelving? Tradition? Romance? Practicality? In the days before the invention of plastic, that ubiquitous, malleable material that we now take so for granted, wood was the logical and singular option. But fortunately it was also perfect. Like naturally aging cheese, wood “breathes”, it holds moisture without being wet, pulling it both out of the cheese, but also helping keep the aging space at a steady level of humidity. Not unlike the natural stone walls and bricks of the pre-modern aging space. Wood shelves used in aging room also take on the same family of fantastically helpful microflora – yeasts, molds, and especially bacteria – that help create distinctive, out-of-this-world cheeses. The usefulness of these microbes has not only to do with flavor, but also with the final safety of the cheese.

Given what I have just told you about how awesome wood shelving is, why isn’t everyone using it? (At least 60% of American Cheese Society cheesemaker members do) Or at least trying to use it? First it is, not surprisingly, highly discouraged thanks to the stance of our federal friends.  Second, the knowledge of how to properly care for wood is tucked away in the minds of a few and only a smattering of books and papers. Third many make only fresh cheeses where aging is not used. And finally, it is more work. More work is not what most cheesemakers need or can even contemplate. Let me tell you about our experience with wood shelves in our own aging room.

Wood Shelves at Pholia Farm

A few years ago we got permission from our inspectors to use wood shelves as long as we consulted with Dr. Lisbeth Goddik,Oregon State University’s Dairy Extension Specialist – a darned amazing woman. She suggested routine cleaning of the shelves with mild soap and warm water, then after rinsing with plain water either wiping the boards down with vinegar or a lactic acid bacteria wash. We did both. We marked which side of each shelf was treated with vinegar and which with bacteria. After aging the cheeses for many months, and before selling them, we swabbed the shelves and sent samples of the cheese to Agrimark lab. All results, for cheese and shelves, whether vinegar or lactic acid bacteria washed, were free from pathogens. So why did we stop? Ironically enough it was another aging room reality that is on the FDA’s hit list (not recent hits list…) cheese mites. I won’t go into too much detail about these little buggers (see one of my most popular posts for all of the itchy details), but what is pertinent is that the dark underside of the cheese sitting on the board was very desirable real estate for the mites. This required more frequent cheese rind labor, something that we were not prepared to do at that time. But I am now.

 So Why the Ruling?

Consider for a moment that the FDA is tasked with an enormous responsibility. As that responsibility grows and food systems expand it becomes more expeditious to simplify. This means generalized rules that apply to everyone – versus thoughtful, logical exceptions. Think about it, before a couple of decades ago, you would be hard pressed (like one of those fabulous wood aged European Comtes) to find any US made cheese that was aged in a cellar type situation with a natural rind. Consequently the paradigm for aging became a squeaky clean walk in cooler. The regulations that developed reflected that reality. With the looming burden of the Food Safety Modernization Act, it’s not surprising that they are now seeking to streamline and enforce existing regulations, rather than allow states to take the responsibility of allowing exceptions.

As we move forward as cheesemakers, I think we need to nurture a new paradigm, one in which the aging room is not treated as a processing room, but as a separate type of space in which a different set of GMP’s apply. When I was at a cheese science conference in England, it was repeatedly said that “The dairy/cheese plant is NOT A HOSPITAL”, nothing could be more true in a room in which you are counting on microbes to flourish.

What Can We Do?

I am a member of the American Cheese Society’s Regulatory and Academic committee. This morning (June 10th) we finalized the press release and position of the largest body of cheese professionals in the United States. (See the document at: http://www.cheesesociety.org/wp-content/uploads/2014/06/ACS-Statement-on-Safety-of-Aging-Cheese-on-Wood.pdf )

So support ACS (join if you are not a member), contact your state representatives, let the FDA know how you feel, and most importantly keep buying and making great cheese! Now, I am going to go put those beautiful Pacific maple shelves back in the aging room. Watch out cheese mites, I’m watching you!

References
The best overall summary of the topic: Donnelly, Catherine, Cheese and Microbes (2014), American Society for Microbiologists, 171-174
Ak, N. O., Cliver, D. O., & Kasparl, C. W. (1994). Decontamination of Plastic and Wooden Cutting Boards for Kitchen Use. Journal of Food Production, 57, 23–30.

Guillier, L., Stahl, V., Hezard, B., Notz, E., & Briandet, R. (2008). Modelling the competitive growth between Listeria monocytogenes and biofilm microflora of smear cheese wooden shelves. International Journal of Food Microbiology, 128, 51–57.

Mariani, C., Briandet, R., Chamba, J.-F., Notz, E., Carnet-Pantiez, A., Eyoug, R. N., & Oulahal, N. (2007). Biofilm ecology of wooden shelves used in ripening the French raw milk smear cheese Reblochon de Savoie. Journal of Dairy Science, 90, 1653–1661. 

Mariani, C., Oulahal, N., Chamba, J.-F., Dubois-Brissonnet, F., Notz, E., & Briandet, R. (2011). Inhibition of Listeria monocytogenes by resident biofilms present on wooden shelves used for cheese ripening. Food Control. 

Nese, AK, Cliver, Dean, Kaspar, C. (1994). Cutting Boards of Plastic and Wood Contaminated Experimentally with Bacteria. Journal of Food Protection, 57(1), 16–22.

Oulahal, N., Adt, I., Mariani, C., Carnet-Pantiez, A., Notz, E., & Degraeve, P. (2009). Examination of wooden shelves used in the ripening of a raw milk smear cheese by FTIR spectroscopy. Food Control. 

Schvartzman, M. S., Maffre, A., Tenenhaus-Aziza, F., Sanaa, M., Butler, F., & Jordan, K. (2011). Modelling the fate of Listeria monocytogenes during manufacture and ripening of smeared cheese made with pasteurised or raw milk. International Journal of Food Microbiology, 145 Suppl 1, S31–S38. 

Zangerl, P., Matlschweiger, C., Dillinger, K., & Eliskases-Lechner, F. (2010). Survival of Listeria monocytogenes after cleaning and sanitation of wooden shelves used for cheese ripening. European Journal of Wood and Wood Products, 68(4), 415–419. 

 

Once a Day Milking – a Viable Option for Quality of Life

Think about it, 75-80% of the milk for about half the labor, half the chemicals, half the grain, AND evenings (or mornings) with a few extra hours of “free” time. Once a day milking (OAD), as opposed to the more conventional twice a day (TAD), is a popular option in several other countries as a way to improve working conditions for farmers. When milk stays in

Milking can be an enjoyable time, especially for observers

Milking can be an enjoyable time, especially for observers

the udder for 24 hours, though, there are some management concerns that must be addressed. Let’s take a look at why OAD might be a good choice, some of the drawbacks, and some of the surprising benefits. First, let me tell you what drove us (or led us) to give it a try.

I had written about the option of milking OAD in my first book, The Farmstead Creamery Advisor. I knew of two commercial dairy farmers, one with cows and one with goats, that only milked one time a day. The former as a way to make up for the lack of extra labor to do these tasks while the farmer was at market during evening milking hours, and the latter as a way to ensure time spent with young children and family. I read about this option in a French dairying document and while in Argentina, learned that many farmers there were intentionally selecting for and breeding cows that did well being milked OAD. I was tempted to give it a try, but as our herd of Nigerian Dwarf goats has been on official milk testing, through Dairy Herd Improvement, for the last 10 or more years, I was very nervous about potentially ruining their records. It also felt very “naughty”.

Then our youngest daughter Amelia, my cohort in goats and barn slave, moved out. Reality check! I was trying to finish writing a third book (about small dairying) and found myself doing far more chores than ever before. Since I am always preaching to cheesemakers and dairy folks about making choices that sustain your both your livelihood and lifestyle (translated not wanting to run away from the farm or divorce your spouse), I realized we needed to give it a try.

What do the Experts Say?

SCC and Mastitis: The first question that people usually ask, is doesn’t once a day milking lead to mastitis? The data says that most animals experience an initial increase in somatic cell count (SCC) but it does not correlate with an increase in mastitis causing organisms within the udder. The initial increase is followed by a decrease in SCC, but usually it stays more elevated than on twice a day milking. (Our experience has had different results). For cows that might already have a low grade udder infection (subclinical mastitis) there is an increased likelihood that once a day milking will lead to acute mastitis. This makes sense, since milking more frequently is one of the best treatments for an udder infection – an empty udder helps “starve out” the invading microbes. Increased SCC alone, does not indicate mastitis. So if you are planning on trying this technique, you should closely monitor SCC’s before switching and after.

Udder with large storage capacity - at start of milking

Udder with large storage capacity – at start of milking

Volume and Components: The research (you can read two articles whose links I have provided below) indicates that production dropped by an average of 15-20% depending upon the animal breed, age, and stage of lactation. In most of the studies, cows held their production levels best, when milked TAD until the peak of their lactation was reached. (For most goats this is at 100 or so days, but for Nigerian Dwarf goats, more like 60 days into the lactation) Interestingly, udder anatomy also played a role. Cows (and in our herd so far goats too) with a larger cistern, that’s the animals own milk bulk tank, were able to maintain good production levels – especially when compared to those with udders made up of more productive tissue and a smaller cistern. In the data, Holsteins typically had more productive tissue and smaller cisterns than cows such as Jerseys. But no matter what the breed, selective breeding for this characteristic can accomplish the desired udder type.  See the photos for an example of one of our two LaMancha does with large cistern capacity. (Indeed, her milk production has increased on 1x a day milking).

In the studies, milk components – butterfat and protein – increased, potentially meaning an increase in cheese yield for cheesemakers. But enzymes also increase, which could lead to shorter shelf life for fluid milk and coagulation or aging

At the end of milking the entire udder is empty and the cistern area is quite visible

At the end of milking the entire udder is empty and the cistern area is quite visible

changes for cheese. I could not find information that delved into this aspect. The cheesemakers I know that milk OAD do not seem to have any issues.

Feed Usage and Body Condition: Grain consumption, if fed at milking time only, can decrease by half and dry matter intake (hay and forage) decreases as well. In general, cows body condition scores improved and a side effect of lower rates of hoof and leg problems resulted.

Our Experience

The first night, boy did I feel like I was slacking off. I also expected the goats to be a little peeved, but no one seemed to have any issues. For the next two – three mornings, the two higher producers had tight udders and one dripped a little milk. After a few days, their production adjusted itself to simply just a full udder. Total milk production for a 24 hour period fell from 12 gallons to 7.5 and then after 6 weeks, came back up to 8.  As of this writing, we are about 10 weeks into the experiment, and production varies between 7.25 – 8 gallons a day. This is amazing to me, as by now many of the does should be dropping a bit and we had four does that had been in milk for about 18 months, and I expected these to start drying off, but they are holding pretty well. Nigerian Dwarfs tend to peak much earlier than standard breed does, so this factors into our lower numbers as well. I am paying close attention to the does that are holding their volume the best.

After four weeks we had our first DHI milk test. The results reflected what the research shows, components go up as do somatic cell counts (SCC). Aha! you say, mastitis will be a problem.   Our increase – to a herd average of 282,000 for the Nigerians and 500,000 for the LaMancha and Lagerians (our Lamancha Nigerian crosses) was still well within our year round normal. Components went way up as well, almost a full 2% for fat and 1% for protein. During this time our cheese yield increased from our normal (for our hard, aged cheeses) of about 14% (on our hard cheeses) to 16%. (If making it just with Nigerian milk, the yield was 17.5%). So the usual 20 gallons of milk produced 3 or 4 more pounds of cheese (from 23.8 pounds to 27.2 pounds).  If we had been milking twice a day, there would have been about 25 gallons of milk which would have yielded (at 14% yield) 30 pounds of cheese. So only about 3 pounds less cheese for a lot less work, feed, and chemicals.

After eight weeks we had our 2nd DHI test. Interestingly, components and SCC all went back to normal, but total herd production held, thanks to the high producing LaMancha and crosses. During test week, we were having a heat wave of all the days over 100F, so I am hoping that was what affected components, as they just don’t spend as much time browsing when the weather is so severe.

Here are the test day herd numbers comparing one year to the next:

June 2012, Twice a day milking: Nigerians: Milk = 2.8 pounds, Fat = 5.92%, Protein = 4.20 %, SCC = 134,000

July 2012, Twice a day milking: Nigerians: milk=2.6 pounds, fat = 6.2%, protein 4.00%, SCC 76,000

June 2013, Once a day milking, Nigerians: Milk = 2.1 pounds, Fat = 7.4%, Protein = 4.26 %, SCC = 282,000

July 2013, Once a day milking: Nigerians: milk = 1.6 pounds, Fat = 5.83  , Protein 4.46 %, SCC = 86,000 (Note temperatures were over 100F during the days surrounding this milk test)

Here are how some of our better milkers are holding up:

Brown Sugar (2nd freshening 2 year old ND) May TAD: 3.1 pounds, June OAD: 2.7 pounds, July OAD: 2.7 pounds

Cocoa (first freshening yearling ND) May TAD: 2.8 pounds, June OAD: 2.6 pounds, July OAD 2.0 pounds

Prudence (first freshening, but extended lactation 50:50 Nigerian LaMancha) May TAD: 3.5 pounds, June OAD 4.6 pounds, July OAD 3.5 pounds

Wanda (2nd freshening 2 year old LaMancha) May TAD, 9.2 pounds, June OAD 8.9 pounds, July OAD 9.3 pounds . (This is the doe whose udder shots are above)

I will definitely update this post once our August test is complete. For now, most of the doe’s production has lowered, but we didn’t  have any does in 2012 that were on extended lactations, that really has to make a difference. The purebred LaManchas and Lamancha crosses are doing better than most of the Nigerian Dwarfs, no surprise there, either. But I believe I can improve upon these numbers by paying close attention to the does who can sustain it well – as we already do by testing how they do with extended lactations, and then choosing those genetics.

Stay tuned!

Update: 9/15/13 – Just found this research paper on high producing Alpine Goats on once a day milking. really great! http://www.journalofdairyscience.org/article/S0022-0302(09)70879-3/fulltext

http://www.cowtime.com.au/edit/QuickNotes/QUICKNOTE_1.4_VERSION_3.PDF

http://www.dairynz.co.nz/file/fileid/27389