The milk taste test
Jenny White on how to produce great-tasting goat's milk
Milk taken from a healthy goat in hygienic surroundings and stored correctly in sterile containers should be sweet smelling and free from any noticeable flavour. A good indication of taint-free milk is when your visitors need to enquire whether or not you’ve served them cows’ or goats’ milk on their breakfast cereal or in their tea. I would describe goats’ milk as clean tasting, less cloying and slightly less sweet than cows’ milk with perhaps an occasional hint of coconut. The other day I asked a friend’s teenage daughter if she had tried goats’ milk.“Yuk!” she said. The look of distaste on her face had me convinced that she had had a bad experience somewhere. But no, the young person admitted she had never actually tasted goats’ milk and could give no logical explanation for her aversion.I don’t know which I find more frustrating, the consumer who has this ingrained aversion to goats’ milk, the consumer who has had one bad experience of poorly produced goats’ milk and refuses to try it again, or the one who assumes the milk is awful because they tried a goats’ cheese once and didn’t like it. I would like to be able to convince all smallholders that keeping a couple of dairy goats is a big step towards self-sufficiency but, it would seem, I first need to explain why some goats’ milk doesn’t taste as good as it should.Human health concernsIt’s not for no reason that dairy products attract so much attention from the environmental health department and other food agencies. Milk is an ideal medium for growing bacteria and absorbing taints from extraneous sources. Poor dairy hygiene can lead to nasty-tasting milk but it also has the potential to cause illness when specific bacteria are present. Bacteria reproduce at an alarming rate. Temperature is critical to their development as the figures below show.
Correct cooling not only slows down the growth of bacteria but also inhibits the activity of the enzyme lipase. Lipase will do you no harm but it’s responsible for imparting a ‘goaty’ taint to the milk. There seems to be a small minority of consumers who actually relish this flavour in their goats’ milk! I came across an article on the internet, written by a commercial cheese maker, extolling the presence of high levels of lipase which, said the writer, “gave goat cheese its distinctive flavour”. This may be acceptable, and even welcome, to the cheese connoisseur but, to most families, the presence of any noticeable goatiness is a real turn-off. Anyone choosing to sell goats’ milk must be licensed and their milk must undergo regular microbiological tests to ensure it’s not harmful to health. Supermarkets will also demand, as an extra measure, that it’s heat treated, to ensure all bacteria are killed off and homogenised to ensure it has a shelf-life in excess of 10 days. This will affect the flavour. I’ve purchased supermarket goats’ milk with almost no distinguishable flavour but, on other occasions, the same brand has been unmistakably goats’ milk – not unpleasant, just different to cows’ milk.LipolysisLipolysis, the release of excessive amounts of fatty acids into the milk, is responsible for the distinctive goaty flavour of some milk. Poor dairy hygiene and careless milking practices often shoulder the blame for goaty tasting milk but this is only partly true. The characteristic goaty flavour only becomes apparent with over activity of the lipase enzyme. Because the enzyme works with bacteria, a high bacteria count in the milk will exacerbate the situation but even the most hygienic milking regime can’t always prevent it.Bacteria may be present as a result of sub-clinical mastitis. Hormonal activity at oestrus and after kidding is often responsible for brief periods of tainted milk in some goats, and subjecting goats’ milk to excessive agitation will damage the fragile cells and also create this fatty acid taint. High lipase activity is often particular to an individual goat and generally only in the circumstances mentioned above.However, there are goats that manifest high levels of lipase at all times of their lactation. These goats are fortunately rare, but if you have such a goat, please don’t damage the reputation of goats’ milk by offering her milk for general consumption. Lipase cannot survive at a temperature of 56°C, therefore heating the milk to this temperature immediately after milking will destroy the enzyme and prevent any taint developing. This is a good way of testing for this fatty acid taint. If you have a goat with high lipase activity, pasteurising her milk as soon as possible after milking could solve the problem.External contaminationContamination of milk from external sources is usually fairly easy to identify and is invariably the result of careless storage. Never recycle plastic containers. Those that have held fruit juice can impart strange fruity flavours to the milk. Any that have previously held milk are notoriously difficult to sterilise because plastic has a softer, less robust, surface than glass or stainless steel. Containers that have held branded spring water can be used once but are then best discarded.Milk stored in the fridge should always be in a sealed container. Some excellent glass jugs are available, designed to stand in the door of the fridge, and they come complete with a plastic lid. As the milk isn’t in direct contact with the plastic, though, it doesn’t pose the same threat as a plastic jug or a recycled plastic bottle.
An unpleasant metallic taint in milk is the result of chemical traces left on equipment due to inefficient rinsing. Oxidation produces a cardboard flavour in the milk. It’s not a common cause of milk taint but will occur in milk left uncovered for any length of time in sunlight or under fluorescent light. Food
Taints that occur in very fresh milk fall into two categories. The most straightforward and possibly the easiest to diagnose are the transient taints connected with the consumption of strong flavoured foods. Large quantities of swede, cabbage or kale need the maximum time for digestion prior to milking. They are best presented immediately after a milking. Sugar beet pulp is a welcome and palatable addition to a goat’s diet, especially during winter but, if it’s fed to excess, it will impart a fishy taint to the milk.
It’s difficult to control what a goat chooses to eat while she’s free ranging but being aware that several plant species can be problematic will help to manage the situation. There are several items listed under the heading of Plants that can taint milk in HMSO Book of Poisonous Plants. Some, for example hemlock, yew, horsetail, bracken, buttercup, henbane and laburnum are poisonous to a greater or lesser degree, and if eaten in any quantity, the goat isn’t likely to live long enough for milk taint to be a problem!
Other plants known to taint milk include wild garlic, elderflower, mint, fools’ parsley, birdsfoot trefoil, shepherd’s purse, ivy leaves (a useful tonic in small doses but beware of the poisonous berries), oak, cress, sweet clover (melilotus), wood sorrel and various plants from the compositae family. Apart from those known to be poisonous, there’s no need to ban these plants from a goat’s diet, but if you notice off flavours in the milk that can’t be explained any other way, a walk around the pasture observing what the goats are eating may give you an answer. It’s also worth noting that carrots and peas sweeten the milk.
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The second category of tainted fresh milk involves the health of the goat and is a much more complicated issue. Mastitis, metabolic disorders, worms and mineral deficiencies all have an effect on milk production and flavour. Mastitis is usually accompanied by physical changes in the milk such as clots and stringiness. In severe cases the goat will appear ill and be running a high temperature. Her milk looks distasteful and is obviously unfit for consumption.
Goats suffering from sub-clinical mastitis will show no symptoms other than a lowered milk yield. The milk will look normal but the taste test will reveal a slight saltiness. This must be investigated as the goat could be shedding harmful bacteria into her milk.
Ketosis or acetonaemia is caused when the goat can’t consume sufficient energy foods for her needs and is unable to digest protein efficiently. Acute cases are recognised by the smell of keytones present in the milk and often on her breath – the smell is distinctive, of pear drops or nail varnish. The milk will also taste strangely sweet. The condition occurs shortly after kidding and is accompanied by a reluctance to eat concentrate at the very time she should be having maximum rations. Ketosis is a life threatening metabolic disorder caused because the goat isn’t eating and is living off her body reserves. It won’t get better by itself but responds quite quickly when treated with drenches available from the vet.
Sometimes it’s difficult to describe an off-flavour. Is it bitter? Does it lack sweetness? Does it leave an aftertaste? When I kept goats commercially, my taste test awarded marks out of 10. I awarded full marks for milk that tasted wholesome, creamy and sweet, that I knew would be enjoyed by small children. It was rare for any goat to achieve less than eight.
If any goat did have a problem, it occurred soon after kidding and, in my experience, was more likely to be related to its metabolism rather than its hormones. Vitamin B12 is produced in the rumen. A deficiency affects the goat’s metabolism, and according to the Goat Veterinary Society, is the most frequent cause of tainted goats’ milk. Normal healthy goats receiving a well-balanced and mineral rich diet shouldn’t suffer any deficiency but there are certain conditions, notably infection from worms and shortage of cobalt, which will upset this delicate balance and hinder the production of vitamin B12.
Bitter-tasting milk is often blamed directly on a shortage of the trace element cobalt. The full story is that cobalt is essential for the production of B12 and as it’s not stored in the goat’s system, it must be available in the goat’s diet on a daily basis. A diet containing a wide variety of plant species, either fresh or as hay, and ideally from a herbal ley containing chicory, together with the provision of a mineral supplement formulated for goats and a cobaltised mineral lick should ensure there is no shortage of cobalt.Worm control is an essential aspect of goat husbandry and even a relatively mild worm infection will inhibit the production of B12. Therefore, if your goat is giving tainted milk, check your worming routine and arrange a faecal egg count.
Lack of published research means that goat keepers often have to try and work out their own management strategies. Some goat keepers routinely inject newly-kidded goats with vitamin B12. Others maintain that tempting their goat with a Marmite sandwich gives good results. I’ve heard of the problem of bitter tasting milk being resolved by giving a goat proprietary antacid tablets for a few days. The calcium carbonate appears to address the calcium to phosphorus ratio that can be upset following kidding.
A diet high in roughage but with insufficient energy foods to meet the goats’ requirements will result in strong-tasting milk. This often occurs after kidding and rights itself after a week or so but should be viewed as a warning that diet management during and after kidding wasn’t perfectly suited to the goat’s needs.
All off-flavours in milk have a cause and should be investigated and, if necessary, corrected. If the milk isn’t destined for human consumption, it doesn’t really matter if it tastes of wild garlic or has been left to oxidise under a fluorescent light. If lack of vitamin B12 or an inappropriate diet is the cause, the taint is a warning that all is not right with the goat and her long term health could be jeopardised.
This article is from the June 2006 issue of Country Smallholding magazine. << To order back issues click the link to the left.