Milk Powder Production

ROTRONIC HUMIDITY FUN FACTS Milk Powder Production Powdered milk in general owdered milk or dried milk is a manufactured dairy product Pmade by dehydrating liquid milk through several drying processes until it is a powder. One purpose of drying milk is to preserve it; milk powder has a far longer shelf life than liquid milk and does not need to be refrigerated. Milk Powder Facts • In the last three decades, world milk production has increased by more than 50 percent, from 482 million tons in 1982 to 754 million tons in 2012. • India is the world’s largest milk pro - ducer, with 16 percent of global pro - duction, followed by the United States of America, China, Pakistan and Brazil. History and Production while retaining all the desirable • Since the 1970s, most of the expan - n the 13th century, Marco Polo natural properties of the milk such sion in milk production has been in reported that soldiers of Kublai as color, flavor, solubility and nutri - South Asia, which is the main driver of milk production growth in the I Khan carried sun-dried milk on tional value. developing world. their expeditions. In more recent Whole (full cream) milk con - • Milk production in Africa is growing times, milk has been dried in thin tains about 87% water. Skim milk more slowly than in other develop - films on heated rollers. The earliest contains about 91% water. During ing regions, because of poverty and – in some countries – adverse cli - patents for this process date from milk powder production water is matic conditions. the turn of the last century. Such removed by boiling the milk under • The countries with the highest milk roller drying was the main method reduced pressure at low tempera - surplus are New Zealand, the United of producing milk powders until the States of America, Germany, France, ture in a process known as evapo - Australia and Ireland. 1960s when spray drying became ration. The resulting concentrated • The countries with the highest milk prevalent. The manufacturing of milk is then sprayed in a fine mist deficits are China, Italy, the Russian milk powder is a very big business into hot air to remove further mois - Federation, Mexico, Algeria and in the 21st century. Indonesia. ture thus forming a powder. Milk powder manufacture is a • An evaporator supplying concen - Approximately 13 kg of whole milk trate for a 15 tons per hour spray simple process able to be per - powder (WMP) or 9 kg of skim milk dryer contains up to 100,000 meters formed on a large scale. Production powder (SMP) can be made from of tubes. Approx. 150,000 cows are involves the gentle removal of needed to keep the plant running 100 liters of whole milk. continuously. water at the lowest possible cost under stringent hygiene conditions continued 1 ROTRONIC HUMIDITY FUN FACTS Why the need to measure humidity? Optimum dryer performance can be attained by monitoring the inlet and outlet flow to and from the dryer. Both, air temperature and relative humidity are measured. In most cases two probes are installed on each dryer. One is installed on the inlet and one on the outlet exhaust. The relative humidity and temperature meas - urement will then be used to bal - ance the dryer for optimum drying, thus reducing energy costs. Milk powder processing plant. Milk powder for a specified time ranging from a milk and it destroys bacteria, inac - production process few seconds up to several minutes tivates enzymes, generates natural (pasteurization: 72 ° C for 15 s). Pre - antioxidants and imparts heat sta - SEPARATION heating causes a controlled denat - / STANDARDIZATION bility. The exact heating/holding uration of the whey proteins in the The conventional process for the continued production of milk powders starts with taking the raw milk received at the dairy factory and pasteurizing BULK BUFFER SCRAPED BUFFER and separating it into skim milk STORAGE SILO SURFACE EVAPORATOR TANK and cream using a centrifugal HEATER SEPARATOR PRE - cream separator. If WMP is to be PASTEURIZER HEATER manufactured, a portion of the cream is added back to the skim milk to produce a milk with a stan - HOMOGENIZER dardized fat content (typically 26- 30% fat in the powder). Surplus cream is used to make butter or ATOMIZER CYCLONES anhydrous milk fat. DRYER PREHEATING The next step in the process is PACKER “preheating” during which the standardized milk is heated to tem - peratures between 75 and 120 ° C. FLUID BED The milk is held in this condition 2 ROTRONIC HUMIDITY FUN FACTS Milk powder production process PREHEATING (continued) regime depends on the type of product and its intended end-use. High preheats in WMP are associ - ated with improved shelf life but reduced solubility. Preheating may be either indirect (via heat exchang - ers), or direct (via steam injection or infusion into the product), or a mixture of the two. Indirect heaters Clockwise from above: powder milk generally use waste heat from being bagged. Milk powder stored other parts of the process in order in a warehouse in California, US. to reduce energy costs. EVAPORATION In the evaporator, the preheated milk is concentrated in stages or “effects” from around 9.0% total solids content for skim milk and SPRAY DRYING idized powder removing water to 13% for whole milk, up to 45-52% Spray drying involves atomizing the point of a moisture content total solids. This is achieved by the milk concentrate from the between 2-4%. boiling the milk under a vacuum at evaporator into fine droplets. This temperatures below 72 °C in a PACKAGING AND STORAGE is done inside a large drying cham - falling film on the inside of vertical Milk powders are immensely more ber in a flow of hot air (up to 200 tubes, and removing the water as stable than fresh milk but protec - °C) using either a spinning disk vapor. This vapor, which may be tion from moisture, oxygen, light atomizer or a series of high pres - mechanically or thermally com - and heat is needed in order to sure nozzles. The milk droplets are pressed, is then used to heat the maintain their quality and shelf life. cooled by evaporation and they milk in the next effect of the evapo - Milk powders readily take up mois - never reach the temperature of the rator which may be operated at a ture from the air, leading to a rapid air. The concentrate may be heated lower pressure and temperature loss of quality and caking or lump - prior to atomization to reduce its than the preceding effect. Modern ing. The fat in WMPs can react with viscosity and to increase the plants may have up to seven oxygen in the air to give off-flavors, energy available for drying. Much effects for maximum energy effi - especially at higher storage tem - of the remaining water is evapo - ciency. More than 85% of the water peratures (> 30 °C) such as found in rated in the drying chamber, leav - in the milk may be removed in the the lower lattitudes of the Tropics. ing a fine powder with around 6% evaporator. Evaporators are Milk powder is packed into either moisture content with a mean par - extremely noisy because of the plastic-lined multi-wall bags (25 kg) ticle size typically of <0.1 mm large quantity of water vapor trav - or bulk bins ( 600 kg). diameter. Final or “secondary” dry - elling at very high speeds inside ing takes place in a fluid bed, or in the tubes. a series of such beds, in which hot air is blown through a layer of flu - 135 Engineers Road, Hauppauge, NY 11788 Tel. 631-427-3898 • Fax. 631-427-3902 • [email protected] 3.

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