3- Preparing Raw Materials Containing Complex Carbohydrates Flashcards
Complex carbohydrates
Grains, potatoes, agave, starch & fructans, long chains of sugar (glucose or fructose), more stable way for plants to store sugars
Starch
In all grains (barley, corn, wheat, rye, rice, sorghum), potatoes, formed in plant cells by bonding glucose molecules, as bond forms, a molecule of water released, can contain 10’s of 1000’s of glucose molecules, wrapped into tight granules for easier storage
Starch conversion
3 elements: modification, gelatinisation, enzymatic hydrolysis
Modification
Only for grains, starch granules not stored in living cells, kept in 3-D protein net, needs to be broken down to release starch granules
Gelatinisation
Starch granules insoluble but if exposed to water over a period of time, they start to unravel & become soluble in water, can be sped up with heat
Enzymatic hydrolysis
Once starch granules unraveled enzymes needed to break them into individual glucose molecules, enzymes not used up or destroyed so small amount needed, speed is temp dependent, inactive if too cold, effectiveness increases with rise in temp, all have optimum temp, if too high become ineffective or can be destroyed
Enzymes
Catalysts that start reactions that might not otherwise happen or speed up rate of reactions
Hydrolysis
To break each bond between individual glucoses in starch, a molecule of water is required
Amylase
Enzymes required to break up starch
Cereal plant
Grow from a grain, die in a single year, flowers & seed (grains), contain embryonic plant with store of starch to feed on
Husk
Hard outer covering, protects
Bran
Different layers, for barley has important role in creation & release of enzymes
Germ
Part that grows into new plant when conditions warm & damp, germination
Endosperm
Where starch granules stored, grain ripens & starch granules secured in 3-D protein net
Making green malt
1- grain is dormant
2- initial phase when grain swells with water
3- 1st visible signs of growth, root emerges
4- roots clearly id’ed, growth halted, modification completed & amylase enzymes released, roots removed
Glucose to starch to glucose
1- plant bonds up to 20,000 glucose molecules releasing water
2- plant rolls up large starch molecules into tight granules & stores them in protein net
3- modification- protein net broken by enzymes or heat
4- gelatinisation- heat used to unravel starch molecules making them soluble
5- enzymatic hydrolysis- amylase helps water react with glucose in starch, breaking bonds, no limit to # of times enzyme performs this task
European traditions for converting starch
Malting, relies on enzymes from barley (endogenous enzymes)
Making a sugary liquid from barley
2 stages:
1- malting (modification takes place)
2- milling & mashing (gelatinisation & enzymatic hydrolysis occur)
Malting
Tricks grain into starting to grow (germination), warm location, soak with water, drained & soaked again several times, grain swells, shoots & roots appear, constantly turned, stops root from knotting together, releases heat generated & keeps at constant temp, ensure all grown at same rate
Green malt
Growth continues, roots as long as grain
Kilning
Growth stopped, heated & dried (warm, dry air), modification & enzyme release needs to be complete before kilning
- If too early- protein structure not broken down & difficult for enzymes to access, may not be enough enzymes
- If too late- too much starch consumed by plant while growing, reducing amount of sugar available
Malted barley
Once dried any attached roots removed, stored in cool, dry conditions, can store for several months
Milling
Cracks open grains creating grist, makes starch more accessible for mashing
Grist
Particles of various sizes, from large husk fragments to flour