Food Processing & Preservation


Flashcards on Food Processing & Preservation, created by Cleo Smiley on 05/06/2015.
Cleo Smiley
Flashcards by Cleo Smiley, updated more than 1 year ago
Cleo Smiley
Created by Cleo Smiley about 9 years ago

Resource summary

Question Answer
what is food processing? The conversion of raw animal and plant tissue into forms that are convenient and practical to consume. e.g Wheat flour.
What can processing food remove? Substances such as: phyphate, polyphenols and oxalate which can affect nutrient utilization.
Advantages of food processing. Mechanical processing, soaking, fermentation and germination/malting- can increase bio-availability of some nutrients. E.g. phytate inhibits iron, zinc, and calcium absorption.
what is food preservation? Prevents food from being spoiled by the action of enzymes and micro-organisms.
How do enzymes affect food? The alter texture, taste & colour. E.g. Apples browning when cut Fat/oil becoming rancid.
how do micro-organisms and yeast affect food? Microorganisms and yeast cause mould to grow, due to the nutrient and water content of food.
Advantages of food preservation: INCREASES: 1)safe storage of food 2) availability- out of season foodstuff. 3)availability- Transportation easier 4) shelf life and reduces production costs.
Definition of food preservation: Use of specific thermal & non thermal techniques to: * Minimize the # of spoilage microbes in food. * make food safe- extended shelf life.
What should be maintained in food preservation? Nutritional value Texture Flavor of food.
What are methods of preservation & storage? Heating cooling reducing water content irradiation chemical preservatives novel Techniques
What are 2 types of heating methods? Pasteurizing & heat sterilizing.
What are 2 types of cooling? Freezing & Refrigeration.
What are 5 types of reducing water content? Sugaring (Jam) Salting Pickling Drying Smoking.
What are 3 other types of preserving food methods? Irradiation, chemical preservatives & Novel techniques.
What is pasteurization and what effect does it have on food? Mild treatment (Temp between 80 °C-90 °C) Minimizes pathogenic microbes. Effect on food: Minor changes to nutritional & sensory characteristics of foods. Shelf life extended by a few days or weeks.
What are some foods that are pasteurized and how is this done? Milk Heated for 15 sec @ 72 °C Destroys pathogenic organisms.
What are some public health concerns with raw/unpasteurized milk? Banned in Scotland. In the UK 0.01% of raw milk. Associated with food borne diseases. mishandled raw milk= 3x more hospitalization than other food borne diseases.
What is heat sterilization? Complete destruction of organisms Effect on food: Increases shelf life up to 6 months @ ambient temperature.
What is an example of food that is heat sterilized and how? Milk -Heated for 15mins @ 12 °C -destroys all contaminating bacteria -causes flavour changes Loss of Vit c & B Vitamins.
What is UHT? UHT= Ultra heat Treated/ Ultra High Temperature processing. -Higher processing temperatures for a shorter time. Shelf life @ least 6 months (No Fridge)
example of UHT food and how. UHT Long life milk, juice, yogurt, wine Heated for 1 sec @ 135 °C -destroys all bacteria tastes better than sterilized more widely available- abroad.
What is Blanching? Blanching= heating food to 75 °C-85 °C for 1-8 Minutes. Food heated rapidly to a pre-set temperature, held for a pre-set time , cooled rapidly to near ambient temperatures.
What happens in blanching? What are Nutrient losses/gains in Blanching. Examples? It inactivates autolytic Enzymes. It is a pre-treatment before canning/freezing. There are minimal losses. Examples: Vegetables.
What is canning? Food heated and sealed in an air tight container. Destroy microbes + prevent re entry 2 ways of processing: *Boiling- Water bath *Pressure canner.
What foods can be canned? Vegetables, meat, pasta.
Are there any gains or losses in canning? Texture + taste changes Longer shelf life Nutritional losses- Vit C Nutr Gains: Lycopene + Dietary fiber.
What is freezing? Food frozen below -18 °C Domestic freezers (-6 °C to -12 °C) Preserves food for months/years if properly stored. Stored in bulk- cost effective.
Are there any changes in freezing? minimal change 2 flavour + Nutrient loss Emulsions= destabilized Damage to cells by ice crystal growth
What is refrigeration? House hold fridges = 2-8C T > 10 C avoided
Are there changes in refrigeration? Reduces rate of biochemical + microbiological changes Extends shelf life of fresh + processed food Biochem & Physical changes during Fridge storage= loss of quality- limit shelf life
What is sugaring? Creates hostile environment- water removed. Food= heated with sugar = packed in sugar
Changes in sugaring? Sugar attracts water= fermentation Increased Energy content.
Examples of foods that are sugared. Jam.
What is salting? Addition on NACL 1 of the oldest methods of preservation Most bacteria, fungi, pathogenic organisms cannot survive in high salt environment – hypertonic nature
Changes in salting? Increases sodium content of food which has health implications- High blood pressure.
What is pickling? Anaerobic fermentation = produce lactic acid (Salt in water=brine) Marinating + stored in acidic solution usually vinegar (acetic acid) pH <5
Changes in pickling? Increases sodium- Health implications.
What is drying? Moisture removed- heat. Moisture content too low for microbes to grow. Sun, air/wind + freeze dry UNLIMITED SHELF LIFE IN PROPER STORAGE
Changes in drying? Nutrients + flavour concentrate Texture changes Chem changes to chlorophyll + carotenoid pigments. Prevented by treatment with ascorbic acid/ or SO2 VITAMIN LOSS
What is smoking? Process of flavoring, cooking or preserving food by exposing to smoke from burning or smoldering plant materials e.g. wood.
Smoking Health concerns? Polycyclic aromatic hydrocarbons (PAH) - production of heterocyclic amines & polycyclic aromatic hydrocarbons that can cause colon cancer
Changes in smoking? Removes water (nutrients concentrate) Forms surface layer Vitamin loss Addition of flavour
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