Milk Powders for Food and health

Milk powders contain all twenty standard amino acids (the building blocks of proteins) and are high in soluble vitamins and minerals. According to USAID the typical average amounts of major nutrients in the unreconstituted milk are (by weight) 36% protein, 52% carbohydrates (predominantly lactose), calcium 1.3%, potassium 1.8%. Their milk powder is fortified with Vitamin A and D, 3000IU and 600IU respectively per 100g. Inappropriate storage conditions (high relative humidity and high ambient temperature) can significantly degrade the nutritive value of milk powder.

Commercial milk powders are reported to contain oxysterols (oxidized cholesterol) in higher amounts than in fresh milk (up to 30μg/g, versus trace amounts in fresh milk). The oxysterol free radicals have been suspected of being initiators of atherosclerotic plaques. For comparison, powdered eggs contain even more oxysterols, up to 200μg/g.
Fonterra, a New Zealand based multinational company, is the world's largest producer of milk powder controlling 40 percent of the global whole milkpowder. The dominance of New Zealand in the global dairy industry, for example Fonterra controls around 30% of the world's dairy exports, has prompted the formation of a futures market for trading whole milkpowder.

History and manufacture of Milk Powders

History and manufacture

While Marco Polo wrote of Mongolian Tatar troops in the time of Kublai Khan carrying sun-dried skimmed milk as "a kind of paste", the first usable commercial production of dried milk was invented by the Russian chemist M. Dirchoff in 1832. In 1855, T.S. Grimwade took a patent on a dried milk procedure, though a William Newton had patented a vacuum drying process as early as 1837. Today, powdered milk is usually made by spray drying nonfat skim milk, whole milk, buttermilk or whey.

Pasteurized milk is first concentrated in an evaporator to about 50% milk solids. The resulting concentrated milk is sprayed into a heated chamber where the water almost instantly evaporates, leaving fine particles of powdered milk solids.
Alternatively, the milk can be dried by drum drying. Milk is applied as a thin film to the surface of a heated drum, and the dried milk solids are then scraped off. Powdered milk made this way tends to have a cooked flavor, due to caramelization caused by greater heat exposure.
Another process is freeze drying, which preserves many nutrients in milk, compared to drum drying. The drying method and the heat treatment of the milk as it is processed alters the properties of the milk powder (for example, solubility in cold water, flavor, bulk density).

Uses

Powdered milk is frequently used in the manufacture of infant formula, confectionery such as chocolate and caramel candy, and in recipes for baked goods where adding liquid milk would render the product too thin.
Powdered milk is also a common item in UN food aid supplies, fallout shelters, warehouses, and wherever fresh milk is not a viable option. It is widely used in many developing countries because of reduced transport and storage costs (reduced bulk and weight, no refrigerated vehicles). As with other dry foods, it is considered nonperishable, and is favored by survivalists, hikers, and others requiring nonperishable, easy-to-prepare food.
Reconstituting one cup of milk from powdered milk requires one cup of potable water and one-third cup of powdered milk. Powdered milk is also used in western blots as a blocking buffer to prevent nonspecific protein interactions, and is referred to as Blotto.

The Advantages and Disadvantages of Airlift Bioreactor

The Advantages of Airlift Bioreactor:
1. Simple design with no moving parts or agitator for less maintenance, less risk of defects.
2. Easier sterilization (no agitator shaft parts)
3. Low Energy requirement vs stirred tank
Obviously doesn’t need the energy for the moving parts (agitator shaft).
4. Greater heat-removal vs stirred tank
At the Airlift bioreactor it doesn’t need the heat plate to control the temperature, because the Draught-Tube which is inside the bioreactor can be designed to serve as internal heat exchanger. It is difference to the Stirred tank bioreactor that needs the heat coat or plate surrounding the tank to make warm bioreactor. It is clear enough that the Airlift bioreactor has greater heat-removal compare to Stirred tank.
The Disadvantages of Airlift Bioreactor:
1. Greater air throughput and higher pressures needed
The agitation on the Airlift bioreactor is controlled by the supply air. To adjust the supply air then the higher pressure needed. And if the higher pressure of air needed then more energy consumption needed. And more cost must pay.
2. Inefficient break the foam when foaming occurs
Because there is no blades/shaft as a foam breaker compare with the stirred tank that has it at the surface.
3. NO bubbles breaker
There are no blades that used as a breaker the bubbles which produced from the air supply (sparger)

Stirred Tank Bioreactor with shaft agitator

The Advantages of Stirred Tank Bioreactor with shaft agitator:
1. Disperse air bubbles
The blades that used as agitator can break the bubbles which produced from the air supply (sparger).
2. Increase oxygen transfer efficiency
Obviously the efficiency of oxygen transfer in liquid will increase during the agitation.
3. Foam Breaker
At the surface of liquid the blades can be use to break the foam. This method can decrease the utility of additive to break the foam.
4. Axial impeller at top to drive liquid downward
Using a special axial impeller to driven the liquid on the surface downward to achieve the optimum circulation.

The Disadvantages of Stirred Tank Bioreactor with shaft agitator:
1. More complicated for scale up with agitator shaft
More detail calculation that involved size, material, energy of the agitator for the scale up this bioreactor.
2. Risk of mechanical damage caused by agitator shaft
3. Need more energy to disperse bubbles and increase Oxygen efficiency
4. Need more energy, time and cost for agitator shaft
For the scale up bioreactor then the energy, time and cost consumptions will needed.

Bioreactor Characteristic of Baker’s Yeast Production

Bioreactor Characteristic of Baker’s Yeast Production
1. Using Saccarahomyces cerevisiae as a seed yeast
Baker’s yeast is produced from the genus and species of yeast called Saccharomyces cerevisiae. The scientific name of the genus of baker’s yeast, Saccharomyces, refers to “saccharo” meaning sugar and “myces” meaning fungus. The species name, cerevisiae, is derived from the name Ceres, the Roman goddess of agriculture. Baker’s yeast products are made from strains of this yeast selected for their special qualities relating to the needs of the baking industry.

2. Using molasses as a medium
Molasses obtained from the beet or sugar cane extraction.

3. Submerged
Submerged in here means the seed yeast and the medium immerse on the water tank.
At the past, before the submerged bioreactor technology appears, the scientist usually use the tray bioreactor. But because this method is inefficient for producing large commercial quantities, it fell quickly to the wayside with the emergence of submerged tank systems, which are designed to handle significantly higher volumes.

4. Fed-batch fermentation process
This hybrid of batch and continuous operations is found in many types of processes. One of the more frequently used is initiating the bioreaction in the batch mode, until the growth-limiting substrate has been consumed. Then, the substrate is fed to the reactor as specified (batch) or is maintained by an extended culture period (continuous). For secondary metabolite production, in which cell growth and product formation often occur in separate phases, the substrate is typically added at a specified rate.

5. Stirred tank
The most common type of aerobic bioreactor in use today is the stirred-tank reactor, which may feature a specific internal configuration designed to provide a specific circulation pattern. Ideal for industrial applications, this unit offers manufacturers both low capital and operating costs. For laboratory experiments with smaller volumes, the mixing vessel is typically made of glass. Stainless steel tank construction is the standard for industrial applications involving larger volumes. The height-to-diameter ratio of the vessel can vary, depending on heat removal requirements.


The operating principles of the stirred-tank bioreactor are relatively simple. The sterile medium and inoculum are introduced into a sterilized tank, and the air supply typically enters at the bottom. For optimal mixing, the tank features not only an agitator system but also baffles, which help prevent a whirlpool effect that could impede proper mixing. In the early stages of the process, warm water may be circulated through the baffles to heat up the system; later, cool water may be circulated inside of them to keep the process from overheating. The number of baffles typically ranges from four to eight. As the bioreaction progresses, the bubbles produced by the air supply are broken up by the agitator as they travel upward. Many types of agitators are currently used, with the most common one being the four-bladed disk turbine. Newer designs featuring 12 or 18 blades, or concave ones, have also been shown to improve the hydrodynamics. At the top of the tank, exhaust gas is discharged and the product flows back down, where it is drained from the tank. In a continuous flow stirred-tank reactor, the substrate is continuously fed into the system and the product is continually drawn out and separated, with the producing organism recycled back into the tank for reuse. As with conventional chemical reactors, bioreactors can be placed in series or parallel with controlled recycle streams.

Bioreactor Parameters

Bioreactor Parameters
1. Controlled temperature
2. Optimum pH
3. Sufficient substrate (usually a carbon source), such as sugars, proteins and fats
4. Water availability
5. Salts for nutrition
6. Vitamins
7. Oxygen
8. Gas evolution and
9. Product and byproduct removal.

Definition of Bioreactor

By definition, a bioreactor is a system in which a biological conversion is affected. Although this definition can apply to any conversion involving enzymes, microorganisms, and animal or plant cells, for the purposes of this article, we will limit the definition. The bioreactors referred to here include only mechanical vessels in which (a) organisms are cultivated in a controlled manner and/or (b) materials are converted or transformed via specific reactions.
In other words, bioreactor made to make our own conditions that required for optimum result of fermentation.

The baker’s yeast production process

The baker’s yeast production process flow chart attached below can be divided into four basic steps. In order these steps are, molasses and other raw material preparation, culture or seed yeast preparation, fermentation and harvesting and filtration and packaging. The process outlined in the flow chart takes approximately five days from start to finish.

General Flow Chart










The basic carbon and energy source for yeast growth are sugars. Starch can not be used because yeast does not contain the appropriate enzymes to hydrolyze this substrate to fermentable sugars. Beet and cane molasses are commonly used as raw material because the sugars present in molasses, a mixture of sucrose, fructose and glucose, are readily fermentable. In addition to sugar, yeast also require certain minerals, vitamins and salts for growth. Some of these can be added to the blend of beet and cane molasses prior to flash sterilization while others are fed separately to the fermentation. Alternatively, a separate nutrient feed tank can be used to mix and deliver some of the necessary vitamins and minerals. Required nitrogen is supplied in the form of ammonia and phosphate is supplied in the form of phosphoric acid. Each of these nutrients is fed separately to the fermentation to permit better pH control of the process. The sterilized molasses, commonly referred to as mash or wort, is stored in a separate stainless steel tank. The mash stored in this tank is then used to feed sugar and other nutrients to the appropriate fermentation vessels.

Baker’s yeast production starts with a pure culture tube or frozen vial of the appropriate yeast strain. This yeast serves as the inoculum for the pre-pure culture tank, a small pressure vessel where seed is grown in medium under strict sterile conditions. Following growth, the contents of this vessel are transferred to a larger pure culture fermentor where propagation is carried out with some aeration, again under sterile conditions. These early stages are conducted as set-batch fermentations. In a set-batch fermentation all the growth media and nutrients are introduced to the tank prior to inoculation.

From the pure culture vessel, the grown cells are transferred to a series of progressively larger seed and semi-seed fermentors. These later stages are conducted as fed-batch fermentations. During a fed-batch fermentation, molasses, phosphoric acid, ammonia and minerals are fed to the yeast at a controlled rate. This rate is designed to feed just enough sugar and nutrients to the yeast to maximize multiplication and prevent the production of alcohol. In addition, these fed-batch fermentations are not completely sterile. It is not economical to use pressurized tanks to guarantee sterility of the large volumes of air required in these fermentors or to achieve sterile conditions during all the transfers through the many pipes, pumps and centrifuges. Extensive cleaning of the equipment, steaming of pipes and tanks and filtering of the air is practiced to insure as aseptic conditions as possible.

At the end of the semi-seed fermentation, the contents of the vessel are pumped to a series of separators that separate the yeast from the spent molasses. The yeast is then washed with cold water and pumped to a semi-seed yeast storage tank where the yeast cream is held at 34 degrees Fahrenheit until it is used to inoculate the commercial fermentation tanks. These commercial fermentors are the final step in the fermentation process and are often referred to as the final or trade fermentation.

Commercial fermentations are carried out in large fermentors with working volumes up to 50,000 gallons. To start the commercial fermentation, a volume of water, referred to as set water, is pumped into the fermentor. Next, in a process referred to as pitching, semi-seed yeast from the storage tank is transferred into the fermentor. Following addition of the seed yeast, aeration, cooling and nutrient additions are started to begin the 15-20 hour fermentation. At the start of the fermentation, the liquid seed yeast and additional water may occupy only about one-third to one-half of the fermentor volume. Constant additions of nutrients during the course of fermentation bring the fermentor to its final volume. The rate of nutrient addition increases throughout the fermentation because more nutrients have to be supplied to support growth of the increasing cell population. The number of yeast cells increase about five- to eight-fold during this fermentation.

Air is provided to the fermentor through a series of perforated tubes located at the bottom of the vessel. The rate of airflow is about one volume of air per fermentor volume per minute. A large amount of heat is generated during yeast growth and cooling is accomplished by internal cooling coils or by pumping the fermentation liquid, also known as broth, through an external heat exchanger. The addition of nutrients and regulation of pH, temperature and airflow are carefully monitored and controlled by computer systems during the entire production process. Throughout the fermentation, the temperature is kept at approximately 86 degrees Fahrenheit and the pH in the range of 4.5-5.5.

At the end of fermentation, the fermentor broth is separated by nozzle-type centrifuges, washed with water and re-centrifuged to yield a yeast cream with a solids concentration of approximately 18%. The yeast cream is cooled to about 45 degrees Fahrenheit and stored in a separate, refrigerated stainless steel cream tank. Cream yeast can be loaded directly into tanker trucks and delivered to customers equipped with an appropriate cream yeast handling system. Alternatively, the yeast cream can be pumped to a plate and frame filter press and dewatered to a cake-like consistency with a 30-32% yeast solids content. This press cake yeast is crumbled into pieces and packed into 50-pound bags that are stacked on a pallet. The yeast heats up during the pressing and packaging operations and the bags of crumbled yeast must be cooled in a refrigerator for a period of time with adequate ventilation and placement of pallets to permit free access to the cooling air. Palletized bags of crumbled yeast are then distributed to customers in refrigerated trucks.

The Function of Baker’s Yeast in Baking

The Utility of Baker’s Yeast
Yeast is the essential ingredient in many bakery products. It is responsible for leavening the dough and imparting a delicious yeast fermentation flavor to the product. It is used in rather small amounts in most bakery products, but having good yeast and using the yeast properly often makes the difference between success and something less than success in a bakery operation.


The Function of Baker’s Yeast in Baking
In the production of baked goods, yeast is a key ingredient and serves three primary functions:
1. Production of carbon dioxide:
Carbon dioxide is generated by the yeast as a result of the breakdown of fermentable sugars in the dough. The evolution of carbon dioxide causes expansion of the dough as it is trapped within the protein matrix of the dough.
2. Causes dough maturation:
This is accomplished by the chemical reaction of yeast produced alcohols and acids on protein of the flour and by the physical stretching of the protein by carbon dioxide gas. These results in the light, airy physical structure associated with yeast leavened products.
3. Development of fermentation flavor:
Yeast imparts the characteristic flavor of bread and other yeast leavened products. During dough fermentation, yeast produces many secondary metabolites such as ketones, higher alcohols, organic acids, aldehydes and esters. Some of these, alcohols for example, escape during baking. Others react with each other and with other compounds found in the dough to form new and more complex flavor compounds. These reactions occur primarily in the crust and the resultant flavor diffuses into the crumb of the baked bread.

Definition of Baker’s Yeast

Yeasts are single-celled fungi. As fungi, they are related to the other fungi that people are more familiar with. These include edible mushrooms available at the supermarket, common baker’s yeast used to leaven bread, molds that ripen blue cheese and the molds that produce antibiotics for medical and veterinary use. Many consider edible yeast and fungi to be as natural as fruits and vegetables.

Yeast's Cells

Instant Baker's Yeast
Baker’s yeast is used to leaven bread throughout the world and it is the type of yeast that people are most familiar with. Baker’s yeast is produced from the genus and species of yeast called Saccharomyces cerevisiae. The scientific name of the genus of baker’s yeast, Saccharomyces, refers to “saccharo” meaning sugar and “myces” meaning fungus. The species name, cerevisiae, is derived from the name Ceres, the Roman goddess of agriculture. Baker’s yeast products are made from strains of this yeast selected for their special qualities relating to the needs of the baking industry.
The typical yeast cell is approximately equal in size to a human red blood cell and is spherical to ellipsoidal in shape. Because of its small size, it takes about 30 billion yeast cells to make up to one gram of compressed baker’s yeast. Yeast reproduce vegetatively by budding, a process during which a new bud grows from the side of the existing cell wall. This bud eventually breaks away from the mother cell to form a separate daughter cell. Each yeast cell, on average, undergoes this budding process 12 to 15 times before it is no longer capable of reproducing. During commercial production, yeast is grown under carefully controlled conditions on a sugar containing media typically composed of beet and cane molasses. Under ideal growth conditions a yeast cell reproduces every two to three hours.

Milk Powder

Definition

Milk is an opaque white liquid produced by the female mammals, and it provides the primary source of nutrition for newborns, before they are able to digest other types of food. Milk is an emulsion of butterfat globules within a water/protein-based fluid.
The early lactation milk is known as colostrum, and carries the mother's antibodies to the baby. It can reduce the risk of many diseases in the baby. The exact components of raw milk varies by species, but it contains significant amounts of saturated fat, protein and calcium as well as vitamin C. Cow's milk has a pH ranging from 6.4 to 6.8, making it slightly acidic.

Milk reception and pre-treatment of milk

Projecting a milk powder plant involves many unit operations one being the milk reception and pre-treatment. When milk isreceived at the factory, the quality is tested, before it is sent to the storage tanks. Pre-treatment typically involves pasteurization, separation of fat for standardization and then cooling before further storage and/or processing.

Powdered milk

Powder milk is a manufactured dairy product made by evaporating milk to dryness. 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, due to its low moisture content. Another purpose is to reduce its bulk for economy of transportation. Powdered milk and dairy products include such items as dry whole milk, non-fat dry milk, dry buttermilk, dry whey products and dry dairy blends.

Processing Diagram of Milk powders and Yogurt Production

Preliminary

Milk powder manufacture is a simple process now carried out on a large scale. It involves the gentle removal of water at the lowest possible cost under stringent hygiene conditions while retaining all the desirable natural properties of the milk - colour, flavour, solubility, nutritional value. Whole (full cream) milk contains, typically, about 87% water and skim milk contains about 91% water. During milk powder manufacture this water is removed by boiling the milk under reduced pressure at low temperature in a process known as evaporation. The resulting concentrated milk is then sprayed in a fine mist into hot air to remove further moisture and so give a powder. Approximately 13 kg of whole milk powder (WMP) or 9 kg of skim milk powder (SMP) can be made from 100 L of whole milk.

The milk powder manufacturing process is shown in the following schematic and is described in detail below.

Bioprocess Technology

Do you know definition about Bioprocess ? Bioprocess is very important on Food engineering processing. A bioprocess is any process that uses complete living cells or their components (e.g., bacteria ,enzymes, chloroplasts) to obtain desired products

Transport of energy and mass is fundamental to many biological and environmental processes. Areas, from food processing to thermal design of building to biomedical devices to pollution control and global warming, require knowledge of how energy and mass can be transported through materials[mass,momentum,heat transfer.

Food and Bioprocess Technology provides an effective and timely platform for cutting-edge high quality original papers in the engineering and science of all types of food processing technologies, from the original food supply source to the consumer’s dinner table. It aims to be a leading international journal for the multidisciplinary agri-food research community

Topic of Food Engineering

In the development of food engineering, one of the many challenges is to employ modern tools and knowledge, such as computational materials science and nanotechnology, to develop new products and processes. Simultaneously, improving quality, safety, and security remain critical issues in food engineering study. New packaging materials and techniques are being developed to provide more protection to foods, and novel preservation technologies are emerging.

Additionally, process control and automation regularly appear among the top priorities identified in food engineering. Advanced monitoring and control systems are developed to facilitate automation and flexible food manufacturing. Furthermore, energy saving and minimization of environmental problems continue to be important food engineering issues, and significant progress is being made in waste management, efficient utilization of energy, and reduction of effluents and emissions in food production.

Typical topics include:

1. Advances in classical unit operations in engineering applied to food manufacturing
2. Progresses in the transport and storage of liquid and solid foods
3. Developments in heating, chilling and freezing of foods
4. Advanced mass transfer in foods
5. New chemical and biochemical aspects of food engineering and the use of kinetic analysis
6. New techniques in dehydration, thermal processing, non-thermal processing, extrusion, liquid food concentration, membrane processes and applications of membranes in food processing
7. Shelf-life, electronic indicators in inventory management, and sustainable technologies in food processing
8. Modern packaging, cleaning, and sanitation technologies

source : www.wikipedia.org

Definition of Food Engineering

The application of natural science and mathematic by means of studying, experiments to economically utilize materials and natural resources for human welfare

Food engineering is a multidisciplinary field of applied physical sciences which combines science, microbiology, and engineering education for food and related industries. Food engineering includes, but is not limited to, the application of agricultural engineering and chemical engineering principles to food materials.

Food Engineering is the application of engineering design and analysis to the conversion of raw food materials into processed products

Food engineers provide the technological knowledge transfer essential to the cost-effective production and commercialization of food products and services.

If you read on www.wikipedia.org. definition of Food Engineering :

Food engineering is a multidisciplinary field of applied physical sciences which combines science, microbiology, and engineering education for food and related industries. Food engineering includes, but is not limited to, the application of agricultural engineering and chemical engineering principles to food materials. Food engineers provide the technological knowledge transfer essential to the cost-effective production and commercialization of food products and services.

Food engineering is a very wide field of activities. Prospective major employers for food engineers include companies involved in food processing, food machinery, packaging, ingredient manufacturing, instrumentation, and control. Firms that design and build food processing plants, consulting firms, government agencies, pharmaceutical companies, and health-care firms also hire food engineers. Among its domain of knowledge and action are:

• research and development of new foods, biological and pharmaceutical products
• development and operation of manufacturing, packaging and distributing systems for drug/food products
• design and installation of food/biological/pharmaceutical production processes
• design and operation of environmentally responsible waste treatment systems
• marketing and technical support for manufacturing plants.