Sugar, browning and caramelization Flashcards
Enzymatic
Phenols, O2,
polyphenoloxidase
Non-enzymatic
maillard reaction and caramelisation
Enzymatic Browning:
- _________ ________ are responsible for the browning & bruising that often occurs in ripening fruit
- Stage 1: ___________ -> ___________ -> ___________
(Polyphenoloxidase + O2)
- Stage 2: _________ -> ___________ (at pH __ to __)
_____ _____________ and _______ are needed to start
enzymatic browning
Phenolic compounds
Monophenols -> Diphenols -> Quinones
Polyphenoloxidase + O2
Quinones -> Melanins
5 to 8
Cell disruption& oxygen
How to Inhibit Enzymatic Browning:
* _______/________ enzymes e.g. through ____/_____ ______
* Adding _____ to lower pH &/or ______ _______ e.g. lemon juice
* ________ the storage temperature
* Blocking exposure to ______ through the use of coatings (e.g. sugar syrup)
* ______ acid reduces quinones to colourless diphenols OR inhibits PPO??
* Removal of ______ (polyphenoloxidase contains Cu)
* Sulphites
* _______ modification
- Denaturing/deactivating ; heat/high pressure
- acid ; chelate copper
- Lowering
- oxygen
- Ascorbic
- metals
- Genetic
What is the Maillard Reaction?
- A series of reactions between a ______ ______ and ______ ______ which results in the formation of brown
complexes in food
- Maillard browning is the browning of
food as a consequence of the Maillard
reaction
- Reducing sugar: sugars that have a free _____ (ketone or aldehyde) group which can react with a free ____ ____
reducing sugar
amino acids
carbonyl
amino acid
Maillard Reaction results:
- Brown pigments called ________
* _____ compounds – often potent aromas
* _______ compounds – bitter substances
* Desirable - aroma and colour of browned baked goods, cooked meat, chocolate flavour, roasted coffee, production of compounds that can
stabilize food
* Undesirable – off odours and browning with long storage of multiple foods e.g. dried egg whites, milk powder, instant mashed potatoes, reduction in
availability of digestible essential amino acids during storage due to glycosylation, compounds with potential mutagenic properties
melanoidins
Volatile
flavour
Factors influencing the Maillard Reaction
- The sugar: __________ sugars are needed. These include glucose, fructose, galactose, lactose or maltose. ________ is not a reducing sugar but participates after
being broken down to glucose and fructose (e.g. through _____ &/or addition of _____). - The amino acid: ______ react with the _______ in the amino group of amino acids.
Therefore amino acids with _______ ______ in their side chains (e.g. lysine, arginine) are better substrates. Different amino acids results in different end products. ___ _____ _____ are more ______ than _______ ______. - Water: The reaction peaks at a _____ _____ (aw) of ~.
- pH: The reactions are accelerated at _____
- Temperature: Proceeds more _____ at ~___-____°C although can occur (_____) at room temperature
reducing, Sucrose, heat, acids, Sugars, nitrogen, amino groups , Free amino acids, reactive, peptide chains, water activity, 0.6, pH ≥6, quickly, 140-160°C, slowly
Caramelisation:
- Breakdown of ____ due to
* _____ or
* High or low ___
* Involves ____ sugar or sugar ______ with most _____ evaporated
* No ____ ________ is identified as caramel
sugars
heat
pH
dry
syrup
water
single compound
Caramelisation steps:
* 1. ______ (if used) breaks into glucose and fructose
* 2. ___________ are rearranged to give ______
* 3. Enediol converts to ___________ compounds through ________ or ____________
* 4. Further ________ to multiple products e.g. caramelan, caramelen or caramelin groups
* Specific products formed depends on the type of _____,____ and __________
sucrose
Monosaccharides
enediol
α-dicarbonyl
dehydration
β-elimination
degradation
sugar, pH and temperature
Caramel flavours
* ______ - butterscotch
* ______ and ______ - sweet rum like
* ______- - nutty
* ______ - toasty
Diacetyl
Esters
Lactones
Furans
Maltol
Caramelisation – Practical Factors
* Caramelisation occurs at ~ ___°C (sucrose or glucose) or ~____°C
(fructose)
* Increase temperature slowly to allow _______ and _______ to occur
at ~ the same time
* Timing is important – too soon is too ____, too late is _____. As
caramel becomes _____ it also becomes _____ sweet.
* Using _____ sugar can make it easier to identify readiness
170°C
110°C
breakdown
melting
sweet
bitter
darker
less
white
Dextrinisation
* Occurs when _____ is heated without ____ being added
* Temperature rises rapidly beyond that possible with ______
* High energy → _______ ______ of _____ through a chemical reaction with the water in starch
* → The starch molecule is split at ______________ between the _______ units
* → ______: molecules of varying lengths derived from the breakdown of starch.
* ______ taste _____ than starch
starch
water
water
chemical degradation
starch
1 or more linkages
glucose
Dextrins
Dextrins
sweeter
Crystallisation
* Crystallisation – The _______ of crystals from a solution
into a solid, geometric network
* Crystal – _______ _______ of molecules
precipitation
Orderly arrangements
Sugar Confectionary 4 steps
Step 1: Creating a syrup solution
Step 2: Concentrating the contents of this
mixture via heating & evaporation
Step 3: Cooling
Step 4: Beating
Sugar confectionery
From the syrup solution:
* Rapid cooling & beating results in _________ confectionery
e.g. fondant, fudge
From the syrup solution:
* Slow cooling without agitation results in _______ confectionery
e.g. hard lollies, caramels, peanut brittle, toffee
CRYSTALLINE
NONCRYSTALLINE
