Processed Foods.docx

5 Pages
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Department
Food Science
Course Code
F_S 1030
Professor
Clarke- Universityof Missouri- Columbia

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Description
Processed Foods Wednesday, February 12, 2014 4:35 PM What are Processed Foods? • Processed foods are products that have been preserved so they will not spoil as quickly as fresh, whole foods. • Most raw materials are perishable and require processing to prevent loss • Shelf stable products are foods that may be kept at room temperature Why are foods processed? • The primary reason is to reduce or eliminate harmful microbes • Another reason is to stop the loss of nutrients due to enzyme action • Common methods: o Sterilizing o Pasteurizing o Fermenting o Blanching Benefits of Processing • Processed food is more likely to be eaten • Shelf stable foods are ready when we are • Loss of nutrients and quality is slower • Processed foods have less waste • Processed foods take more energy to produce, but use less energy to store Processing Steps • Unit operations are distinct steps for converting raw materials into processed foods • Examples of unit operations o Material handling o Cleaning o Pumping o Mixing o Heat Exchanging o Packaging Types of Processed Foods • Processed whole foods o Canned peas, corn oil, orange juice • Formulated foods o Bread, jams, chocolates • Chilled foods o Ice cream, deli meats, margarine • Prepared foods o Pizza, potato salad, food service Heating • Cooking kills spoilage and pathogenic microbes but does not sterilize food • Blanching is a unit operation to inactivate enzymes • Pasteurization kills pathogens but not all spoilage microbes • Canning sterilizes the product in a container • Aseptic processing sterilizes product prior to packaging Canning Considerations •Types of microbes o Clostridium botulinum, Bacillus, stearothermophilus •Headspace vacuum •Heat treatment o Cold point •Acidity of product Heat Treatment •Conduction involves heat transfer through a material due to molecular movement •Convection involves heat transfer through movement of heated fluid from hot regions to cold •Conducted in a retort or pressure cooker Acidity Factors •The acidity or pH of a product affects the amount of heat treatment needed •Low acid foods are those with a pH greater than 4.6 and aw of 0.85 or more •Acid foods are those that have a natural pH of 4.6 or less •Acidified foods are low acid foods to which acids are added so the pH is 4.6 or less and aw of 0.85 of more Freezing •Freezing is mild treatment that results in less loss of nutrients and quality than heat treatment •Freezing slows the growth of microbes but does not kill them so there may be safety and spoilage problems when thawed Freezing Methods •Still air (freezer at home) •Forced (blast) air (commercial, faster) •Indirect contact •Scraped surface •Individual Quick Freeze (IQF) (keeps things separately frozen) •Cryogenic Drying •Removing moisture reduces the ability for microbes to grow •Even dry foods (flour) contain moisture (10-15%) •Water activity (a ) refers to water that is available for microbial growth • Moisture content is not the same as water activity! Drying Methods •Sun or air •Oven •Vacuum •Spray •Freeze •Drum Concentrating •Removal of water from a liquid food without changing it into a solid is concentration •Common examples are juice concentrates and syrups Curing •Another way to decrease availability of water by adding preservatives •Salt and sugar are the most common choices •Sodium nitrite and sodium nitrate are additional curing agents applied to cured meat products Milling •Cereal grains are milled into flour to improve digestibility •Dry milling separates the seed into fraction based on anatomical structure (bran, germ, endosperm) •Wet milling separate components on anatomical and solubility differences (protein, oil, and starch) (corn starch vs corn oil) Extracting •Involves the r
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