12 - Food Processing Flashcards
Which two sectors form the food industry?
Agriculture - provides fresh produce, minimally processed food or raw ingredients
Food production
What is food processing?
The use of physical, chemical or biological means to convert raw food materials into consumable food products (ingredients or consumer products)
What are the types of food processing methods?
Physical methods - size reduction and thermal treatments
Chemical methods - chemical preservatives
Biological methods - fermentation, enzyme treatment
Novel methods (physical) - high pressure, pulse electric field, irradiation
What are the 3 main effects of food processing on food?
Microbial activity (extend shelf-life, but directly impact sensory quality and nutritive value of food) Sensory quality (texture, smell, taste, appearance, can be desirable or not desirable) Nutritive value (digestibility and availability of nutrients, can be desirable or not desirable)
What are the desirable effects of food processing on nutritive value of food?
Improved nutritional quality of processed food - improved digestibility (moderately denatured proteins are more easily hydrolysed by digestive enzymes), bioavailability of nutrients (e.g., release of nutrients due to destruction of cell walls in plant materials)
What are the undesirable effects of food processing on nutritive value of food?
Loss of certain nutrients, especially vitamin C and folate
What are the physical methods of food processing?
Size reduction
Thermal treatments
- Mild heat - blanching, pasteurisation
- High heat - sterilisation, dehydration, baking and roasting, smoking
- Reduce temperature - chilling, freezing
Novel methods
- High pressure (non-thermal)
- Pulse electric field (non-thermal)
- Irradiation
Physical food processes:
Size reduction affects which macro- and micro- nutrients?
All
All
Physical food processes:
Blanching or pasteurisation affects which macro- and micro- nutrients?
None
Vit C and B complex
Physical food processes:
Sterilisation affects which macro- and micro- nutrients?
All
Vit C and B complex
Physical food processes:
Dehydration and baking, roasting affects which macro- and micro- nutrients?
Fats and proteins
Vit C and B complex
Physical food processes:
Chilling, and freezing affects which macro- and micro- nutrients?
-
Vit C and B complex
Thermal food processes:
What is the effect of freezing on microbial activity in food?
Cold
Decrease microbial growth
Reduce water activity
Thermal food processes:
What is the effect of chilling on microbial activity in food?
Cold
Decrease microbial growth
Thermal food processes:
What is the effect of pasteurisation or blanching on microbial activity in food?
Mild heat
Kills some microbes but require further processing e.g., chilling
Thermal food processes:
What is the effect of sterilisation on microbial activity in food?
High heat
Kills all microbes
Thermal food processes:
What is the effect of dehydration, baking, roasting, and smoking on microbial activity in food?
High heat + others
Kills all microbes
Reduce water activity
Thermal food processes:
What is the effect of freezing and chilling on sensory quality in food?
No detectable changes
Thermal food processes:
What is the effect of pasteurisation and blanching on sensory quality in food?
Slight or no detectable changes
Thermal food processes:
What is the effect of sterilisation on sensory quality in food?
Large detectable changes, sometimes undesirable
Thermal food processes:
What is the effect of dehydration, baking, roasting, and smoking on sensory quality in food?
Large detectable changes, desirable to create flavours
Can a raw ingredient be converted to different products using different food processing methods (e.g., size reduction, thermal, biological)?
Yes
Furthermore, each type of food processing method - thermal or biological can produce more than 1 product from the same raw ingredient (e.g., thermal UHT milk, milk powder, pasteurised milk)
What is the purpose of using food processing methods one after another?
To ensure food safety and product quality (e.g., homogenisation, pasteurisation, chilling)
Novel food processes: What is the effect of high hydrostatic pressure (HPP) on food? Macro-nutrients Micro-nutrients Microbial activity Sensory quality
Affects proteins
-
Reduces microbial activity with pressure
Retains most food quality and maintains natural freshness compared to other physical methods
Novel food processes: What is the effect of short pulses of a strong electric field (PEF) on food? Macro-nutrients Micro-nutrients Microbial activity Sensory quality
-
-
Reduces microbial activity with electricity
Minimal effect on sensory quality
Novel food processes: What is the effect of irradiation on food? Macro-nutrients Micro-nutrients Microbial activity Sensory quality
Affects fat and proteins
Affects vit B complex
Reduces microbial activity with irradiation
Minimal effect on sensory quality
Are natural (unprocessed) foods safe, or safer than processed ones?
Some natural foods contain natural toxicants, and processing makes some natural food safer
(anti-nutritional factors, cyanogenic compounds, mycotoxins)
But some food processing methods generate toxicants too
Process-generated toxicants:
What are the harmful effects of heterocyclic amines (HCA) and how are they generated?
Mutagens, carcinogens
Frying, grilling, roasting, BBQ of fish and meat
Process-generated toxicants:
What are the harmful effects of trans fats and how are they generated?
Increased risk of coronary heart disease by increasing blood cholesterol levels
Fried foods and baked foods
Partially hydrogenated plant oils
Process-generated toxicants:
What are the harmful effects of acrylamides and how are they generated?
Carcinogenic
Commonly found in fried, baked, roasted starchy foods
Temperature and time dependent
Mitigation - reducing cooking temp/time, no over-cooking, asparaginase (enzyme)
