In addition to the most important nutrients (fat, protein), the quality and cost of the milk produced is influenced by its organoleptic and microbiological properties. Feeding-related changes can have a significant impact on milk by transferring aroma and flavor into milk. Oxidation processes (rancidity) also have a negative effect.
Aromas and flavors that are not characteristic of milk can affect milk in the following ways:
Due to direct contact with milk – especially in a warm state – milk picks up the smell of goat’s rue along with the feed. This can be avoided by maintaining milking and milk hygiene.
Fragrant and taste particles from the air of the goat’s rue pass through the inhaled air into the blood, and from there into the milk.
Substances can pass directly from a goat’s digestive tract into milk, or they undergo alterations in the digestive tract, such as betaine from beets, which converts to trimethylamine and gives the milk a fishy taste.
In the second and third cases, it is possible to help through the establishment of feed technology together with proper hygiene in the goat’s house. Strongly smelling feed is fed in small doses after milking, and the goat’s rue is thoroughly ventilated after feeding. In the relatively long period between milking, these substances will be mostly processed by the metabolism of the goat. Such fodder should never be stored directly in the goat’s house (be careful when thawing frozen silos or when storing unsealed silage film bales directly on the aisle).
Influence of different feeds on the taste of milk
Different feeds have different effects on the smell and taste of milk: green rye and green oats, as well as most legumes, especially fresh, cannot be fed thoughtlessly and a lot at one time. Turnip, kohlrabi, rapeseed, rape, when not fed properly and especially when frozen, lead to a pungent smell and a pungent, radish-like taste of milk. Wet silage should be fed more carefully than dried silage. But an unpleasant odor in the goat’s rue, associated with severe indigestion in goats, can also cause an unpleasant smell and taste in milk.
Bacteria in milk and feeding
The amount of bacteria in milk depends on the health of the animals, especially the health of the mammary glands, as well as the hygiene of the premises and milking. Feeding is also somewhat indirectly responsible for the amount of bacteria in milk. Feeding errors that lead to diarrhea in goats (abrupt change of feed, too little “structure” when feeding young and leafy green mass, dirty, missing or frozen feed, too much beet tops or green manure, an extremely large amount of fresh stillage fed, and etc.) help to increase the number of bacteria in milk. Silage containing butyric acid can increase the number of butyric acid bacteria in milk with poor milking hygiene and maintenance, and thus lead to disturbances in milk fermentation in the production of cheese (because of this, there is a ban on feeding silage fodder in the production of Emmentler cheese).
Animal hygiene, housing and milking are essential for perfect milk production. The use of feeds that have a negative effect on the organoleptic and microbiological properties of milk can only take place without economic risk if they are used carefully and deliberately from a feed management point of view.
With a sharp transition of animals to food from pastures, polyene fatty acids from grass are absorbed already in the small intestine and are included in milk fat. As a result, the oil becomes soft (“meadow oil”).
However, very hard and poorly spreadable oils can be influenced. This firm consistency is often observed with higher amounts of corn silage and concentrates (“winter oil”) in the diet.
Milk easily absorbs odors and tastes
Flavors and aromas easily and quickly pass from feed into milk. Poor quality feed is also to blame for the unpleasant taste of milk. If the goats are fed with admixtures of highly aromatic herbs, for example, garlic, onions, fennel, etc., then milk will acquire the smell and taste of these substances in a short time.
According to Dombrowski, after feeding garlic, milk acquires a repulsive taste that remains for a long time even after boiling and cooling. Hansen found that feeding flaxseed meal produces a bitter taste in milk.
Milk with a bitter aftertaste also appears, according to Ryde, after feeding rotten feed, feed with a high content of beets or beet leaves, and raw potatoes. The same effect is caused by the use of rotten straw as bedding. Palmer identified the onset of the bitter taste of milk with progressive lactation. He established a pattern that such milk contains a very large amount of lipase. When it is destroyed by heating fresh milk, this bitterness does not disappear.
After feeding the cabbage to the goats before milking, the milk tastes bad. This taste is less noticeable in cream than in milk. Feeding the potatoes before milking produced only a very slight aftertaste that weathered very quickly.
The widely held belief that feeding fishmeal gives milk a fishy flavor has not been confirmed. So Winberg conducted a study in which he observed how feeding fishmeal from herring affects the taste of milk and as a result found that it did not affect the taste of milk and butter in any way. Bunger came to the same meaning when feeding fishmeal; but this type of feeding had a very negative effect on the structure of the oil. The oil was loose at first; later left on the tongue during melting a hard, rubbery consistency and a bitter aftertaste …
The unique feature of milk, which has a huge surface due to the smallest particles of milk fat, promotes strong absorption of odors, therefore the milk absorbs odors and gases very strongly. A common complaint that milk smells like goats is due to the strong absorption of gases and odors from the air in the barn.
Likewise, milk becomes saturated with foreign tastes and odors when it is in a room with strong odors, especially fresh milk. It is known that even smoking in a room where milk is located can spoil the smell and taste of this product. The influence of aromatic oils, disinfectants, for example, bleach, is even worse.
The observation from practice that milk absorbs smells from the environment the stronger the longer it is in the room and the higher the temperature in it, gave Alto a reason to conduct a study on the absorption of gases by milk and the effect of temperature on this ability. It has been found that the duration of absorption plays a much less important role than the temperature at which the absorption of gases occurs. Milk absorbed odor maximally at a temperature of 35 ° C, and at 50 ° C any absorption ceased.Almost complete release from absorbed gases and odors is possible by heating milk to 70 ° C and subsequent rapid cooling.