Milk Facts - Cow, Goat, Sheep

Source:WorkSmartLiveSmart.com

Not all milk is the same, we all know that, but besides the obvious like the animal and which breed, what is the real difference?  

All milk is made up of water, fat, protein, lactose and minerals but it is the composition of these constituents that makes the difference between them.  The fat and protein vary greatly.  The higher the solids content, the stronger the affect on the acidification and coagulation properties for cheese but also how the human body deals with it in milk form.  The fat and protein content in cow's and goat's milk are fairly similar compared to sheep' milk; however the structure of the fat and protein is what's important.


Fat Content

98% of the fat in milk consists of triglycerides and are made up of fatty acid chains that vary in length. This issue is the size of the fat globules and the type of protein chain.  Sheep and goat’s milk have short to medium chains producing smaller globules, cow’s milk has longer structures. The longer the chain length, the more easily it separates from the water but the more difficult for the human body to breakdown.

While sheep are notoriously difficult to milk, mostly because they have very small teats, the milk is naturally homogenized. This means the cream does not separate out of it but it also makes the milk easier to digest. Sheep produce less milk than their confrere.  The upside is it has a very high fat content with the finest fat globules of the lot.  Goat’s milk come second to sheep’s milk; with cow’s milk a distant third, having the largest fat globules and the longer fatty acid chains. Goat's milk is the closest to human milk and the least fatty of the three. It is the easiest on the human digestive system. It generally requires more milk to make cheese but because of the milks’ fat structure, the cheeses are less suited to aging.

Cow’s milk is the highest in water content of the three, which of course helps produce more quantity-wise.  The typical breeds used for ‘industrial’ milk produce milk that is less well rounded in terms of character.  For drinking, this is not an issue and the fact that due to its' structure, the cream rises and allows for making different percentages of fat content milk.  For cheese production, the regional breeds in most countries produce milk with more complexity and a higher fat content which makes for better cheeses.


Milk Protein

Milk protein differs between milk types.  There are two major types: caseins and whey proteins.  Casein being the major of the two is what transforms when making cheese.  In sheep’s milk 82% of the proteins are casein while it is 80% cow’s milk and 75% in goat’s milk, the rest being whey based. Casein protein has four different types and the proportions differ between the milk types – goat contains more of the beta caseins while cows’ has more alpha caseins with a particular one being the protein responsible for cows’ milk allergies. 

What is important for cheese is that casein coagulates to form the structural backbone of cheese curd. Sheep’s milk coagulates more rapidly and forms much firmer curd thus sheep’s milk produces twice the amount of cheese per unit compared to cow’s or goat’s milk. The richness and cheese yield of sheep's milk makes up for the lower quantity of milk per animal.  Goat’s milk with its lower amount of alpha casein and its beta casein has a lower yield (10 to 15 percent less) and is less adaptable to different cheese type.

It’s the sugar stupid!

Somebody who cannot digest lactose is said to be lactose intolerant. But it is the major sugar – not protein – found in animal milk that causes the problem here.  The intolerance comes when the body’s ability to synthesizing the lactase is compromised.  Lactase is the enzyme responsible for lactose metabolism and in the cheese making process, it is the energy source for our friendly bacteria.

All three of the milk types contain similar levels of lactose; therefore, one is not better than another for those with lactose intolerance when it comes to drinking or using milk.  The good news is that during the process of making and aging cheese, most lactose is lost when the whey drains off and the little that is left begins to convert to lactase.  The older the cheese, the less lactose!  So long aged cheeses like Comté, Beaufort or the Pyrenees sheep’s milk cheeses all have practically no lactose left in them.

Just a fun note:  Milks vary in colour. Cow’s milk tends to be yellow and varies by season because of the level of beta-carotene found in green forages.  Some breeds process this pigment differently or more efficiently and produce very yellow milk – Jersey cows being a good example.  Sheep and goat milks lack beta-carotene because they convert it into vitamin A which is not pigmented so these milks are whiter than cow’s milk.

Side by sidecomparison

Component	Unit	Cow Whole (3.25% fat)	Goat	Sheep
		--- Amount per 100 g ---
Overall Composition
Water	g	88.32	87.03	80.7
Energy	kcal	60	69	108
Carbohydrate2	g	4.52	4.45	5.36
Fat	g	3.25	4.14	7
Protein	g	3.22	3.56	5.98
Minerals (Ash)	g	0.69	0.82	0.96
Vitamins
Vitamin A	µg	28	57	44
Riboflavin (Vitamin B2)	mg	0.183	0.138	0.355
Niacin (Vitamin B3)	mg	0.107	0.277	0.417
Pantothenic Acid (Vitamin B5)	mg	0.362	0.31	0.407
Vitamin C	mg	0	1.3	4.2
Vitamin D	IU	40	12	ND3
Minerals (Ash)
Calcium	mg	113	134	193
Magnesium	mg	10	14	18
Potassium	mg	143	204	137
Sodium	mg	40	50	44
Zinc	mg	0.4	0.3	0.54
Carbohydrate Detail
Lactose4	g	5.26	ND	ND
Fat Detail
Cholesterol	mg	10	11	27
Fatty acids, total saturated	g	1.865	2.677	4.603
Fatty acids, total monounsaturated	g	0.812	1.109	1.724
Fatty acids, total polyunsaturated	g	0.195	0.149	0.308
Source:
http://www.milkfacts.info/Nutrition%20Facts/Nutrient%20Content.htm#Tab2

Lactose Intolerance versus Milk Allergy, bis

from Culture Magazine 2013

My theory on Lactose Intolerance versus a Lactose Allegy has been vindicated!

An article on the Culture Magazine website - Cheeseographic: Lactose Intolerance on October 15, 2013, by Jessie Hazard is very too the point about this ongoing issue.  Lactose to lactase, aged cheeses versus fresh, cow's milk versus goat and sheep, allergy vs intolerance, yep, it's all there in graphic display! 

Want more information?  You can check out other articles on The Kitchen Blog - What is Lactose Intolerance and also Lactose and Cheese: Are You Really Lacotse Intolerant by Nora Singley who was a Cheesemonger and the Director of the Cheese Course at Murray's Cheese Shop in New York City and a chef on The Martha Stewart Show. All very interesting in terms of what you need to know about the two competing enemies of cheese lovers. 

Also here is an interesting bit from Wikipedia on the subject :

Dairy products - Lactose is a water-soluble substance. After the curdling process, lactose is found in the water-based portion (along with whey and casein), but not in the fat-based portion. Dairy products that are "reduced-fat" or "fat-free" generally have slightly higher lactose content. Low-fat dairy foods also often have various dairy derivatives, such as milk solids, added, increasing the lactose content. 

Cheese - Fermentation and higher fat content contribute to lesser amounts of lactose. Traditionally made Emmental or Cheddar might contain 10% of the lactose found in whole milk. In addition, the aging methods of traditional cheeses (sometimes over two years) reduce their lactose content to practically nothing. Commercial cheeses, however, are often manufactured by processes that do not have the same lactose-reducing properties.  


 

Cow's Milk - Bête noire ?

At the fromagerie, we often have people say they can't eat cheese because they are lactose intolerant. These same people invariably tell me that they can eat those made from goat's or sheep's milk.  Really? And why would that be true?  All milks have lactose, but most of the lactose in cheese is either drained away with the whey or converted to lactic acid during the aging process leaving little or no lactose. So how could this be true and what is the issue here? Is there any science to back this up? Is cow's milk harder on the body than goat's or sheep's milk?

Lactose intolerance is very common in adults and not dangerous, but milk allergies are more serious and broad reaching. Understanding the root cause of the problem is necessary because while symptoms associated with lactose intolerance are similar to those of dairy allergies; it is how & to what the body reacts that is different.  It is important to note that a person can be lactose intolerant and also have sensitivity to dairy proteins, i.e., be allergic, but these two maladies are not necessarily coexistent. In the case of lactose intolerance it is the milk sugars (lactose) that cause the hypersensitivity whereas in a milk allergies, it is the milk proteins.

There are different make ups of milk proteins (casein) in all of the milk types. It is the major protein in cow's milk alpha-s1-casein protein, not present in sheep or goat milk, which is to blame for the adverse reaction. The body's immune system attacks them as if they were an invader rather than breaking them down. Since these milk proteins are present in any related milk product, anyone with an allergy to the proteins is susceptible to varying degrees of allergic reaction. And as milk proteins are the main building block of any cheese, for someone with a milk allergy, eating cheese is pretty much impossible.

Those with lactose intolerance have a different problem.  Lactose intolerant people cannot digest lactose (milk sugars) which is different than milk proteins. The body is incapable of metabolizing lactose because of a lack of the enzyme lactase in the small intestines (known as lactase deficiency).  As enzymes help the body absorb foods, not having enough lactase means these sugars stay intact and the intestinal bacteria have a feeding frenzy. So when products containing high levels of lactose are ingested, gas is produced in the intestines and violà, discomfort ensues. 

According to Wikipedia, milk from buffalo has 4.86% lactose, yak 4.93%, unprocessed cow milk 4.7%, goat milk 4.7% and sheep milk 4.6%. So when someone says they are lactose intolerant to cow's milk, the same intolerance to sheep and goat's milk should exist, right?  Well, while these milks contain the same level of lactose, it is thought that goat & sheep milk are more easily digested than cow's milk because they do not contain the same concentrations of casein (milk proteins). Therefore, there is a strong possibility that folks who can drink non-cow milks with no problem, in reality have an allergy as opposed to being lactose intolerant. 

So what about cheese? Well, in the case of cheese, it comes down to how much actual lactose is still present in the finished product. Because lactose is a water-soluble molecule, higher fat percentages, fermentation, the curdling process and aging have an impact on the amount of lactose that remains in a cheese product.  To begin with, in the early hours of the life of a traditionally produced cheese, most of the lactose present in any milk passes into the whey, which is drained off.  The bit that remains in the cheese curd is converted into lactic acid during the ripening process and disperses as the water content evaporates and the milk proteins become more concentrated. 

The longer the aging, the less lactose is present in the curd.  Not true of milk proteins obviously as the pate is made is primarily made up of these proteins.  Traditional, aged hard cheeses have only about 10% of the lactose that is found in the original whole milk.  For instance, a 24 month old Emmental or Comté, both cow's milk cheeses, have practically no lactose remaining.  So theoretically, even if one is lactose intolerant, one will have problems with fresh and minimally aged cow milk cheese like camembert but not have problems eating long aged cow's milk cheeses.

So why is it that these folks seem to be able to deal with the other milk types?  In buffalo, goat & sheep milk cheeses; the basic milks have smaller fat globules to begin with, which do not clump together in the same was as in cow's milk, thus making the milk naturally homogenized and in general produce a more dense cheese. Assuming you do not have a major protein related allergy, these two factors in conjunction contribute to a higher digestibility of these milks and their respective cheeses. 
None of this is 100% applicable to commercial cheese, i.e., those manufactured by modern processes.  Here these processes generally do not have the same lactose reducing properties, in part due to the elimination of so called 'good bacteria' during the milk pasteurization process and/or the length of aging. 

Another culprit which might be part of this digestive problem can be found in an additive, Lysozyme (additive E1105). The additive is an anti-microbial enzyme which is extracted from fresh chicken egg white and is used for its antibacterial properties primarily in the manufacture of industrial cheeses.  Although it is not always the case, people allergic to eggs (different than dairy) may also be allergic to lysozyme; therefore they often present the same symptoms as someone with a milk allergy. So the rule of thumb for people with egg white allergies might be to avoid commercially made cheeses all together.  Not to fear however, because the use of lysozyme is not allowed in the production of French AOC cheeses (interestingly most being made from raw milk). 

With all this information, it would seem that people with lactose intolerance should be able to eat any, and I would say any traditionally made, milk type cheeses that have been long-aged. No scientific tests have been done to prove this that I can find, so I always try to enlist willing subjects to try a beautiful 24 month old Comté or Beaufort to see if what happens.  If they still report having a problem, then in my opinion, they are more likely to have a milk allergy than being lactose intolerant.