Advances in classical unit operations in engineering applied to food manufacturing
Unit operation is the term used for basic step in the process, unit operations are the physical change and chemical transformation. The classical unit operations involved in food manufacturing along with their applications are:
These unit operations are common for many industries yet serving many different purposes. These unit operations are simplified using three common phenomenons:
- Heat transfer
- Mass transfer
- Momentum transfer
Properties of food products:
The selection of the unit operation is highly dependent upon the properties of food.
- Thermal properties: Thermal properties of food include such as specific heat, conductivity, diffusivity, and boiling point rise.
- Optical properties: Optical properties include color or for some food gloss and translucency.
- Structural and geometrical properties: Shape, density, particle size, and porosity.
- Mechanical properties: Textural and rheological properties.
- Other properties are mass transfer related properties, gelling properties, radiation absorption, and surface tension.
- Internal circulation of fluids: Movement of fluids through the interior of the tube
- External circulation of fluids: Circulation of fluids through the porous fixed bed, pneumatic transport.
- Distillation: separation based on the vapor pressure difference.
- Absorption: A liquid absorbs the component of gas according to the solubility of a gas in a mixture.
- Extraction: It is based on the diffusivity of a mixture in a selective solvent.
- Adsorption: Adsorption is the separation of one or more components of fluids.
- Ionic exchange: exchange of ions between two solutions.
- Humidification and dehumidification: Humidification and dehumidification of a gas.
- Crystallization: Formation of solid glossy particles.
- Dehydration: Moisture removal
Principals of unit operation:
Important law followed by all unit operations are:
Conservation of Mass and energy:
The law of conservation of mass states that mass can neither be created nor be destroyed.it is a rule that what comes in the processing plant must leave from the plant. e.g.
If the milk is fed into the centrifuge to separate it into skim milk and cream, under the law of conservation of mass the milk weight in kilograms entered in the centrifuge must leave as skim milk and cream in kilograms from the centrifuge.
Similarly, the law applies to every component for e.g butterfat, proteins, milk, sugars, and so on.
The law of conservation of energy states that the energy can neither be created nor be destroyed .this means that the total energy entering the plant should equal the total energy leaving.
But this case is complicated because energy can be converted in various forms such as kinetic, potential, heat, chemical, electrical energy, and so on.
For instance, consider the purifying procedure for milk, where milk is siphoned through a warmth exchanger and is first warmed and afterward cooled. The vitality can be considered either over the entire plant or just as it influences the milk. For all-out plant vitality, the equalization must include: the change in the siphon of electrical vitality to motor and warmth vitality, the active and expected energies of the milk entering and leaving the plant and the different sorts of vitality in the warming and cooling sections, as well as the leaving heat, active and likely energies.
To the food technologist, the energies influencing the item are the most significant. On account of the pasteurizer, the vitality influencing the item is the warmth vitality in the milk. Warmth vitality is added to the milk by the siphon and by the high temp water going through the warmth exchanger. Cooling water at that point evacuates some portion of the warmth vitality and a portion of the warmth vitality is additionally lost to the environmental factors.
The warmth vitality leaving in the milk must rise to the warmth vitality in the milk entering the pasteurizer give or take any warmth included or removed in the plant.
Warmth vitality leaving in milk = starting warmth vitality
+ heat vitality included by siphon
+ heat vitality included warming area
– the heat vitality has taken out in the cooling segment
– heat vitality lost to environmental factors.
The law of preservation of vitality can likewise apply to part of a procedure. For instance, considering the warming segment of the warmth exchanger in the pasteurizer, the warmth lost by the high temp water must be equivalent to the whole of the warmth picked up by the milk and the warmth lost from the warmth exchanger to its environmental factors.
From these laws of protection of mass and vitality, a monetary record for materials and vitality can be drawn up consistently for a unit activity. These are called material adjusts and vitality adjusts.
Characteristics of Unit operations applied in food manufacturing
Some of the unit operations involved in food manufacturing treat products on the open conveyor or in open vessels and they also include close human proximity which leads to the question about the hygienic conditions, and due to this microbiological control of the atmosphere and aerobic protection of equipment’s are applied.
Heterogeneity is the part of product quality for example the combination of soft and crispy layers consists of composite objects. The problem persists in these types of food to control the transfer of water in these layers.
Many of the unit operations are results of the industrialization of manual operations in the kitchen.
Breakthrough advances in unit operations:
The recent advances in unit operations using in food manufacturing factories are:
Pasteurization is an excellent thing – thank you, Louis Pasteur and Nicolas Appert. But being “cooked” has its terrible points. Gentleness isn’t always one of the attributes of maximum heat-pasteurization processes.
The pressure of 87,000 psi might not sound mild, either, however its consequences on the feel of ingredients are negligible; its effect on pathogens is deadly. That’s the type of stress carried out in high-stress pasteurization (HPP) systems, which might be cold-pasteurizing meats, juices, ready-to-devour food and different top rate meals merchandise that might go through beneath neath high-temperature pasteurization.
An HPP device packs packaged meals merchandise into torpedo-like cylinders which can be moved into water-stuffed chambers. As the water stress is raised, microorganisms inclusive of salmonella and listeria are killed via way of means of collapsing their molecular walls. The meals product is unaffected. But its packaging ought to be tough.
It’s an extra steeply-priced manner than retorting, however, it’s mild and provides no ingredients (inclusive of antimicrobials), thereby assembly cutting-edge purchaser needs for minimum processing and fewer ingredients.
The robotic enterprise made its mark with inside the Eighties with hundred-unit installations inside the car enterprise that took tough jobs (welding, heavy lifting) far from line employees with tireless efficiency. Few jobs with inside the meals plant healthy that task description.
But there are some. Nowadays, many meals and beverage plant life have at least one robotic. It’s in all likelihood toiling on the cease of the line, stacking bins of product onto pallets. Some plant life has one some ft. upstream assisting to fill the one’s bins with the product. And there’s a developing perception that any time you may get rid of human palms from the process, you may boom meals protection and employee protection.
Advancement development comes gradually and carefully to the food and refreshment industry. Unveiling a blonde Oreo to the expending open is much simpler, a surer business wager and more satisfactory than, state, utilizing radiation to slaughter microbes in meat. Or on the other hand, growing a burger in a petri dish.
The Food Industries are continuously focusing on new technologies used for the manufacturing of food .these new technologies and recent searches in the field of unit operations are bringing the new soul of comfort and ease to production, handling, preservation, and distribution of food.