Food science tutorials Flashcards
fresh or cellular foods are made from what
animal/plant tissue
what are the orders of structure in natural foods (3 different levels)
Atoms -> Molecules –>Macromolecules –>Supra-molecular complexes -> Organelles -> Cells -> Tissues
[chemistry, biochemistry]
Tissues ->Organs ->Systems ->Whole organism [physiology]
Whole organisms -> Communities -> Ecosystems [biology]
what is the basic structure unit for animal foods
muscle/ meat structure
how long is a muscle cell, myofibril
1 metre long
what is myofibril surrounded by
sarcolema (cell membrane)
what is the order for myofibrils
Myofibrils -> muscle fibers ->higher orders of muscle structure or whole meat [increasingly complex structure]
what is Muscle supplied with
blood vessels
what examples of connective tissue
Muscle is supplied with blood vessels; these and covering fascia and tendons are all connective tissue
what gives meat its tough texture
tendons and other connective tissue
what fills muscle cells
sarcoplasm
what does the sarcoplasm contain
organelles (mitochondria, lysozomes, endoplasmic reticulum, nucleus) and enzymes of glycolytic and Krebs cycle
what is the energy source for meat
glycogen
where are High amounts of myoglobin are found
aerobic muscle or “red meat”
what does white meat contain
White meat (esp. poultry & fish) contains low levels of myoglobin
look at diagrams in booklet
what do Plant leafy tissue components include and what do they contribute to
epidemal cells, parachymer cells, phloem, xylem
(all contribute to structure)
what do the seeds & roots of many plants contain
vast quantities of starch granules
why is the large central vacuole of plant cells important
Provides outward pressure leading to firmer texture
* Compartmentalizes phenol,
organic acids and other waste
components
* Separates phenol substrates
from the enzyme PPO in the cytoplasm and so avoids browning in the absence of tissue damage
what does the cell wall of plant cells consist of
The cell wall consists of a multiple layer of cellulose and hemi-cellulose fibrils embedded in a pectin comment Cell wall components may be lignified producing woody- texture
what are prepared foods typically made from
secondary ingredients
what are the structures of secondary ingredients
fabricated not cellular
Food structure involves interactions between
water, polysaccharides, proteins and lipids.
what are the 3 main colloidal systems
emulsions, foams, gels
what are the 2 major classes of food emulsions
- Oil inwater(O/W)emulsionsaremadefromlipid(oil)phasedispersewithinacontinuous
water phase (e.g. milk) - Water-in-oilemulsionismadefromwaterphasedispersedwithinanoilcontinuousphase
(e.g. margarine)
what does the droplet size of O/W emulsions determine
milky colour
The type of emulsion formed depends on the surfactant used, which can be
Inedible: detergents or soaps
Edible: monoglycerides, diglycerides,
phospholipids and Tweens, Span & Food
proteins
what is Emulsion destabilization caused by
- Creaming
- Flocculation
- Oswald ripening
what are food foams
A foam is air droplet surrounded by water layer Surfactants are needed to produce stable foams Examples of edible foams include:
* whipped topping
* head on a pint of Guinness * ice cream (a frozen foam) * bread (heat set foam)
what are food gels
Gels are a 3D-network of food polymers, with large amounts of entrapped water that provide structure and texture to a food. Unstable food gels contract by expelling water leading to syneresis.
* Polysaccharide gels can be formed with any straight chain polymer, e.g. amylose, pectin * Example protein gels include:
formed with egg white/blood proteins in heating
Casein forming an acid coagulated gel at pH 4.6 (yoghurt) Casein gels after hydrolysis by chymosin (cheese)
what are some examples of multiple structures in prepared foods
Cooked minced meat > emulsion-gel | Bread > heat set foam-gel | Whipped cream > foam-emulsion
what are emulsions, gels and foams all form the basis of
structure
what are examples of emulsions
oil-in-water, or water-in-oil milk, butter margarine mayo
what are examples of foams
air droplets in water phase- bread whipping topping
what are examples of gels
3-dimensional network of biopolymers that hold large amounts of water
Jelly, jam
Egg white
Yoghurt, cheese
what are the main sources of variability
production, processing, analytical
what substance are involved in the Maillard reaction
chemical reaction between amino acids and reducing sugars that gives browned foods their desirable flavor. The compound that participates in the Maillard reaction is Glycine
what are colloidal systems
give structure, texture, mouthfeel to different products- colloids are formed when one substance is dispersed through another, but does not form a solution. There are many types depending on the state of the 2 substances mixed together e.g gels/foams
what is the difference between true solutions, suspensions and colloidal systems
true solutions have solute particles at the molecular level and do not scatter light, suspensions contain visible solid particles that settle out over time, and colloidal systems consist of colloidal particles that are intermediate in size between true solutions and suspensions
