Recap
The right diet for a dairy herd is a balance of fresh and fermented pasture and a protein supplement. There is a direct relationship between the nutrition of a herd and the level of nutrients in the milk.
Microorganisms in milk lead to rapid deterioration in raw milk. The common milk-pasteurisation technique known as the high-temperature short-time (HTST) protocol requires milk to be heated to 72°C for 15 seconds. HTST pasteurisation doesn’t sterilise milk; it just elongates its shelf life.
The long-term solution to stable, long-life milk is known as ultra-heat treatment (UHT). UHT processing causes the proteins that bind the milk fat globules together to unwrap, releasing sulphur-containing compounds. These aromatic gases impart a sulphurous, cooked smell to the milk.
With current farming technology in the US, dairy farming is responsible for per-kilo carbon emissions three times higher than those of the orange juice industry.
Much work remains to be done to reduce milk wastage and to improve biogas digestion technology at the farm level.
Glossary
Adsorption The process by which atoms, ions, or molecules spread across the surface of a material to form a film
Anaerobic bacteria Bacteria whose metabolisms do not require oxygen
Coalescence The process by which separate regions of the same substance merge to form a homogenous mass
Colloids Small (<1 um) undissolved particles in a liquid; unlike particles in a suspension, colloids do not settle out due to gravity.
Emulsion A liquid mixture of two or more substances that are not dissolved into each other
Eutrophication a detrimental process wherein nutrients are leached from pasture and washed into waterways, leading to deoxygenation of the aquatic environment and algal blooms
High-temperature short-time (HTST) pasteurisation A process that heats milk to a minimum temperature and holds it at that temperature for the required time, followed by immediate cooling of the milk. The regulated minimum heat process for the holding time and temperature combination of milk pasteurisation in Australia is 72°C for 15 seconds.