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Introduction to Unit Processing: Fundamental Concepts
Food Science: Food Science can be defined as the application of basic sciences and engineering principles to study the fundamental physical, chemical, and biological nature of food and the principles of food processing. Food Technology: is the use of information generated by food science in the selection, processing, preservation, packaging and distribution as it affects the consumption of safe, nutrition, and wholesome food.
Food Engineering: The application of engineering concept and principles to the conversion of raw foods into safe consumer products of the highest possible quality. Food engineering involves study of engineering concept and unit operations used in food industry. It should include materials and energy balances, thermodynamics, fluid flow and heat and mass transfer.
Process: Process is the set of methods and techniques used to transfer raw ingredients into food or to transfer food into other forms for consumption by human or animals.
Production of Fruit Juice Concentrate
Unit Operations: Unit operation is a basic step in a process. Unit operations involve a physical change or chemical transformation such as separation, crystallization, evaporation, filtration, polymerization, isomerization, and other reactions. For example, in milk processing, homogenization, pasteurization, chilling, and packaging are each unit operations which are connected to create the overall process. A process may require many unit operations to obtain the desired product from the starting materials.
Unit Operations: Classifications) 1. Fluid flow processes: including fluids transportation, filtration, and solids fluidization. 2. Heat transfer processes: including evaporation, condensation, and heat exchange. 3. Mass transfer processes: including gas absorption, distillation, extraction, adsorption, and drying. 4. Thermodynamic processes: including gas liquefaction, and refrigeration. 5. Mechanical processes: including solids transportation, crushing and pulverization, and screening and sieving.
Unit process A ''unit process'' is one or more grouped operations in a manufacturing system that can be defined and separated from others. Unit process involves a chemical change or sometimes it is referred as chemical changes along with Physical Change leading to the synthesis of various useful product. Example : Hydrogenation, oxidation, nitration etc.
Ø Cleaning Separates contaminants from the raw materials. Ø Sorting Separates the raw material into categories of different physical characteristics such as size, shape and colour. Ø Grading Separates the raw material into categories of different quality.
Heat Transfer Unit Operations These operations are controlled by temperature gradients. They depend on the mechanism by which heat is transferred: Conduction: in continuous material media, heat flows in the direction of temperature decrease and there is no macroscopic movement of mass. Convection: the enthalpy flow associated with a moving fluid is called convective flow of heat. Convection can be natural or forced. Radiation: energy transmission by electromagnetic waves. No material media are needed for its transmission. Thermal treatments (sterilization and pasteurization), evaporation, heat exchangers, ovens, solar plates, etc. are studied based on these heat transfer mechanisms.
HEAT PROCESSING Thermal properties of foods: 1. Specific heat 2. Thermal conductivity 3. Thermal diffusivity
1. Specific heat: is the amount of heat required to increase the temperature of a unit mass by 1 o C or 1 o. F. This is denoted by Cp Q = MCp∆T Factors that influence the specific Heat Ø Moisture content Ø Temperature Ø Pressure 2. Thermal conductivity: thermal conductivity of a product gives in quantitatives terms the rate of heat that will be conducted through a unit thickness of the materials if a unit temperature gradient exists across that thickness. Q = KA d. T/dx Where K= thermal conductivity A = area through which heat flows X = length T = Temperature Applications of thermal conductivity • Prediction of processing time • Heat calculation • thermophysical properties –predictions
Books For Food Engineering 1. Introduction to Food Engineering by R. Paul Sing 2. Food Process Engineering by Heldman 3. Hand book of Food Engineering By Dennis R. Heldman 4. Introduction to Food Process Engineering by P. G. Smith 5. Food Engineering Operation by J. G. Brennan 6. Unit operation in Food Engineering by Gustavo V. Barbosa-Cánovas 7. Fundamentals of Food Process Engineering by Romeo T. Toledo