PROCESSING OF FOODS                                                                                              PROCESSING
                                                                                                                                                           RAW PRODUCT
                                                                                                                                                                PROCESS
                                                                                                                                                             PROCESSED 
                                                                      Michael Ngadi, PhD., P.Eng.                                                              PRODUCT
                                                                      Bioresource Engineering Department
                                                                      McGill University
                                       FOOD PROCESSING                                                                                                       PROCESSING OF FOOD
                                                OPERATIONS
                                                                                                                                   PRIMARY PROCESSING:                             SECONDARY PROCESSING:
                                                                                                                                  - conversion of raw materials                   - conversion of ingredients into 
                                 Food Processing is the conversion of                                                             to food commodities                             edible products 
                                                                                                                                  Eg: milling, chilling, drying,                  - this involves combining foods 
                                 agricultural product to consumable                                                               etc.                                            in a particular way to change 
                                 substances which have particular                                                                                                                 properties. 
                                                                                                                                                                                  Eg: processed meats, dairy 
                                 textural, sensory and nutritional                                                                                                                products, beverages and 
                                                                                                                                                                                  alcoholic drinks, food packaging, 
                                 properties using commercially feasible                                                                                                           baking, freezing, dehydrating
                                 methods                                                                                                                                          canning and bottling.
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                                     WHY PROCESS?                                                                 FOOD PRODUCTS
                              • to convert to edible products                                         Products may be made by several processes. Interactions 
                                                                                                      between product and processes differ.
                              • to preserve 
                                                                                                         Starch products                 Meat products 
                              • to extend availability and provide accessibility                               a. Bread                         a. Products from cattle
                                                                                                               b. Cakes and biscuits            b. Products from pigs
                                                                                                               c. Pasta
                              • to provide variety and choice                                                  d. Rice products           Fish products 
                                                                                                               e. Corn products
                                                                                                                                          Milk products 
                              • to provide convenience                                                   Oil products 
                                                                                                               a. Margarine               Chocolate manufacture
                              • to add value                                                                   b. low fat spreads) 
                                                                                                                                          Drinks 
                        TYPICAL FOOD PROCESSES                                                                   UNIT OPERATIONS
                      Several steps are required to manufacture food products.                                                           • Material Handling
                      The specific details of each may differ, but the basic                         Unique steps or                     • Cleaning
                      principles are the same.                                                                                           • Separating
                                 Source ingredients            Fillings added                        operations taken                    • Size reduction
                                 Delivery of ingredients       Finish applied                        to prepare food                     • Fluid Flow
                                Storage of ingredients           Cooked                              products                            • Mixing
                                 (hoppers, bins, etc.)                                                                                   • Heat transfer
                                                                 Cooled                                                                  • Concentration
                                   Weigh and mix 
                                ingredients - formulation        Stored                              These operations                    •Drying
                                  Mixture shaped or         Packaged and labeled                                                         • Forming
                                 formed – extrusion,                                                 can stand alone                     • Packaging
                                 cutting, rolling, etc.
                                                               Distribution                                                              • Controlling
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                                   TERMS                                        PROCESS FLOWSHEETS
                 • Process Design: the design of food processes             Process flowsheets are graphical 
                   and manufacturing methods, including process             representations of the layout and flow of 
                   flowsheets, design of processing and control             equipment and materials in the plant.  
                   equipment, and economic evaluation of the 
                   process.                                                 PBD: Process block diagram
                 • Plant Design: the design of whole processing             PFD: Process flowsheet diagram
                   plant, including the processing/control equipment,       PCD: Process control diagram
                   the utilities, the plant buildings, and the waste 
                   treatment units.                                         PID: Piping and instrumentation diagram
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             Energy accounting (process 
             block) diagram of tomato 
             paste manufacturing based 
             on an 8 hour shift
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