FOOD PROCESSING II
Date of Experiment Performed: 01/30/2013
Date of Submission: 02/11/2013
Instructor: Iraj Mehrnia
Submitted By: RAMYASHREE. J (100508620)
Lab Partners: Ashok Bikku
ABSTRACT: The main Objective of this experiment is
(1) To become familiar with a spray-drying operation
(2) To observe the overall efficiency of a spray dryer
(3) To measure the moisture content of the final product at ...view middle of the document...
Air may be heated by direct firing of gas or fuel in an airstream or indirectly through a heat exchanger. Indirect heating is often used in the food industry to avoid contamination of food with carbon or dirt from fuel and contact with combustible products that could impart foreign flavors or odors. The primary function of the drying chamber is to provide an intimate mixing of hot air with finely dispersed droplets of the material to be dried in such a way that drying proceeds adequately and that the dry particles have the desired characteristics. The drying chamber may be in the form of a horizontal box or tall vertical tower and may have a relatively simple or extremely complex flow pattern for both air and feed droplets. The primary function of atomization is to generate small droplets that create a large surface area for moisture evaporation. In addition, an atomizer acts as a metering device to control the flow rate of product into the dryer. The three types of extensively used atomizers are centrifugal, pressure spray head, and fluid nozzles.
Coffee, eggs, milk, soups, and baby foods are among the foodstuffs normally spray-dried. The feed may be a solution, suspension, or paste, but the final product is normally a powder with variable physical properties according to the design and operational characteristics of the spray dryer. The process begins with slurry containing 12 to 70% solids, depending on the specific application and feed material. The advantages of this operation are that the process is continuous and adaptable to full automatic control, which increases product output without adding labor. However, the process is quite specific because spray dryers are not general purpose types of equipment. Their narrow range of products serves to improve the efficiency and quality of the final product.
Drying air is an important factor in spray dryer design, as this has great effect on dried product properties by influencing droplet behavior during spray drying.
There different types of spray drying systems. They are:
* Open cycle systems
* Closed cycle systems
* Semi-closed cycle systems.
There are 4 stages in the processing of spray dried food products.
1st stage the liquid feed is atomized into a spray of droplets.
2nd stage it involves the spray-air contact, mixing and droplet/ particle flow.
3rd stage it combines drying and particle formation. And in the final stage particle separates from the drying air and dried product is discharged.
In the 1st stage there are 3 basic designs of atomizers based on the source of energy utilized in the droplet formation process.
* Rotary atomizers.
* Pneumatic nozzle atomizers.
* Pressure nozzle atomizers.
Rotary atomizers consist of a rotating wheel or disk centrifugal energy is used as source of energy in the droplet formation process. And then the liquid feed is introduced centrally.
Pneumatic nozzle atomizers...