Fat-dependent quality traits Flashcards
What is the composition of a fat molecule?
Glycerol backbone
3 fatty acids
Groups of fatty acids
Short-chain, saturated
medium-chain, saturated
long-chain, saturated
monosaturated (monoenoic acids, MUFA)
Polyunsaturated (polyenoic acids, PUFA)
Importance of omega 3 fatty acids
Good for cardiovascular disease
good for immune system
good for brain development
risk of rancidity, off-flavours
When are trans fatty acids formed?
during industrial, incomplete hardening of fats (vegetable oils)
when heating above 130°C (frying)
through bacterial metabolic processes in the rumen
What is the risk of consumption of trans fatty acids?
Increasing risk of cardiovascular diseases
Consumption of trans fatty acids naturally occuring in milk fat are not considered detrimental for health
Importance of conjugated linoleic acids (CLA)
+ Cardiovascular diseases
+ anticarcinogenic
+ Performance-enhancing (used by athletes)
- occurrence only together with other trans fatty acids
Indicators to predict the effect of dietary fats on coronary heart diseases in humans
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What are direct traits related to texture of fat?
Firmness / adhesion / spreadability
Melting properties
- solid fat index
- melting profile
- melting point
Recrystallisation point
Dripping point
Empty (watery) fat tissue
Iodine number
Soep formation index
Linoleic acid content
Ratio of neutral/complex lipids
Possibilities of modification of fat firmness by genetics
Species differences
Almost no direct genetic determination in meat/fat tissue, milk and egg
Genetically determined higher/lower degree of saturation of function lipids compared to storage lipids; less fat deposition -> softer fat
Meat and fatty tissue:
- localisation differences in hardness of different fat tissues
- higher slaughter age: firmer fat when animals are fatter
Modification of fat firmness by feeding
Intake of individual fatty acids: fat content and fatty acid profile of the diet
- prediciton of transfer rate with iodine number product in pigs
- efficiency of transfer: monogastric animal > ruminant
- Efficiency of transfer in ruminants: milk fat > body fat
- medium-chain and long-chain fatty acids: firm body fat
- conjugated linoleic acids: hard fat (pigs)
- Unsaturated, especially polyunsaturated fatty acids: soft fat
Starch: firm far due to de-novo synthesis of long-chain saturated fatty acid
minor nutrients: softer with niacin (milk) and Cu (lard) when given in supra-nutritional doses
Low feeding intensity causes softer fat in meat when animals are less fat; maybe also one of the causes of the ‘empty’ fat tissue
Modification of fat firmness by processing measures
Separation (e.g. backfat, fat fractionation into liquid and solid)
Mixing of different fats (e.g. meat products containing beef and pork
Technological faat hydrogenation (not wanted in natural products like butter)
Slight increase of saturated fatty acids by cooking
Stages of fat spoilage (Verderb)
Release of fatty acids from triglycerides (butyric acid from milk fat)
Randcidity: Oxygen accumulation on double bonds
Measures to prolong fat shelf life - feeding
Feeding:
- increase of proportion of saturated fatty acids, reduction of PUFA
- antioxidants in feed: vitamin E (continuously or at once), selenium, BHT, Ethoxiquin
- no use of spoiled fat
Measures to prolong fat shelf life - processing
Low temperature and short duration of heating during processing and cooking
prevention of contamination with copper containing materials
hygiene, pasteurisation/sterilisation to reduce microbially caused oxidation
Meat products: retrospecitve application of antioxidants
Milk: Maintenance of the fat globule membrane as a natural protection against oxidation poblematic products: intensively homogenised, intensively heated milk; butter milk
Egg: Protection of egg shell as natural protection against oxidation
Measures to prolong fat shelf life - Storage
Exclusion of (UV) light by suitable packaging material or brown stained glass bottles
High hygienic standard during storage
