Chapter 3.1: Carbohydrates
3.1 Sugar
Properties of sugar - Solubility & Hygroscopicity
How solubility of sugar affect the food❓
1. the high solubility sugar helps to increase viscosity (thickening) = affect food texture !
2. the sugar absorb water in the food ↦ lower water activity↦ inhibit the growth of microbial = preserve the food!
Btw, the solubility depends on the temperature of water and the type of sugar😇
The high temperature helps to dissolve sugar faster and the solubility increases.
Fructose has higher solubility than normal sugar (sucrose)!
If fructose vs. lactose, which one produce softer candy❓
Fructose will produce softer candy as fructose has high solubility which can dissolve more water where both candy cook in the same temperature and time. Lactose will produce harder candy because less dissolve with water and more sugar crystal(those cant dissolve) available in the solution.
In the market, syrup and invert sugar also commonly used in food.
glucose corn syrup ≠ invert sugar ! because it only contains glucose
fructose corn syrup = invert sugar
Btw, what is the function of invert sugar in food ❓
invert sugar is more soluble than normal sugar ↦ high affinity of water (humectant) ↦ absorb water ↦ solubility increase ↦ prevent crystallization & lower water activity & retain mositure = Prolong shelf life ! 😲😲😲
How invert sugar is made❓
Invert sugar is from the inversion of sucrose hydrolysis.
Heat 🔥& acid 💧help in the process of inversion.
Next, Hygroscopicity!
hygroscopicity of sugar give the function as humectant in food !
the hygroscopic of sugar can be good or bad.
for example, add into baked goods like bread- moist inside(good)😋; add too much into candy - sticky(bad)😕
Brown sugar is more hygroscopic than normal sugar.
how about icing sugar vs caster sugar in same amount of water ❓ which one higher solubility❓
Icing sugar contain starch which will help to absorb part of the water and hence better solubility compared to caster sugar 😲😲😲
Role of sugar in food - Sweetness, Tenderizer, Browning, Crystallization & Preservation
① Sweetness
Factor affecting sweetness - Preference, temperature, type of sugar & concentration
② Tenderizer
Why sugar can act as tenderizing agent in baked products❓
Baked products contain flour ↠ starch & protein ↠ glutenin and gliadin
Glutenin and gliadin help to develop gluten when mixing with water ↠ produce elasticity!
The addition sugar will tenderize the baked products.
Sugar compete the water with the glutenin and gliadin ↠ when lack of water ↠ less starch gelatinization ↠ gluten formation ⇊ ↠ extend time for CO2 to expand ↠ need longer time to suspend - Give lighter and airy product!
③ Browning
Maillard reaction and Caramelization = non enzymatic reaction
Maillard reaction : involve the condensation of reducing sugar + amino acid + heat ; condition = high pH, low moisture
Caramelization : only involve the pyrolysis of sugar [ sugar + dry heat - high temperature ]; form aromatic molecules
④ Crystallization
Concentration of sugar influence crystallization.
Factors affecting crystallization & food quality❓ water content initiate solution & rate of crystallization
The crystallization of sugar can be controlled [depends on what is the outcome you want]
For example, you want softer texture crystalline candy like fudge - add invert sugar/ acid; increase sugar concentration if you want chewy/brittle candy.
⑤ Preservation - due to the solubility of water ↦ control moisture lvl in food ↦ inhibit the growth of microbial 👍
Alternative sweetener is not carbohydrates although they taste sweet.
Starch granule - amylose (linear) & amylopectin (branched)
4 Functionality of starch in food
1. Water binding
2. Thickening ability
3. Gelling agent
4. Retrogradation
The functionality is mostly affected by the Changing state of starch when exposed to heat & water!
What will happen when [Heat + excess water + Stach]❓
Hydrogen bonds break down
amylose swelling (Amylose swell more compared to amylopectin) - granule rupture
keep heating↝Gelatinization occur
Gelatinization temp. = 60 to 70 degree celsius.
Gelatinization -> Continue heating -> Pasting (viscosity increase and reach the peak viscosity)
Gelation happens (sol/gel) (depends on the percentage amylose & amylopectin)
When the starch fully gelatinized, the solution is transparent.
During storing time, Retrogradation occur (crystallized the starch = "hydrogen bond continue forming (orderly alignment) between amylose molecules" when cooled in room temperature)
BUT, Retrogradation is undesirable; example: staling of bread; but freezing can inhibit retrogradation. Retrogradation is reversible process.
Then, store in chiller,Syneresis happens in cold temperature.
Btw, the swelling power depends on the granule size and amylopectin content.
Large granule size and high amylopectin content will give higher swelling power.
The outcome gelation is depend on ratio of amylose and amylopectin, why❓
Amylose (linear chain- from firm gel); Amylopectin (branched - soft gel)
because linear chain structure easily re-associate back when cooled down
Basically, it can conclude that factors affecting the viscosity of sols& gel :
- Types of starch - composition of amylose and amylopectin
- Concentration of starch - the ratio of water & starch
- Extent of heating
- Agitation - stirring will weaken gel structure - Fragmentation
Any other factors affect the viscosity of sols&gel❓
INGREDIENT!
Sugar
Sugar increases/decreases viscosity?
Ans: sugar gives negative impact to viscosity.
Why increase/decrease?How sugar affect viscosity?
Ans: Sugar is hygroscopic and it will bind with water. This caused the sugar and starch will fight for water. if lack of water for starch, the starch cannot gelatinize and pasting cannot reach peak and less viscous.
Fat& protein
Fat decreases viscosity. why?
Fat will coat the starch, no water can go into starch granule, lumping happens and no gelatinization happens, less viscosity.
Acid
Acid will undergo hydrolysis, weaken bonding and viscosity decreases.
how about syneresis? 😔how to solve it?
Modified starch!
- change by physical method (pregelatinised starch) or chemical modification (cross-linking starch& substition starch)
- advantages: control syneresis by retain moisture; improve texture, cell structure, increase volume, enhance shelf-life.
How about resistant starch❓
- low calorie
- low water-holding capacity
- as "dietary fiber"
3.3 Fiber
Soluble vs. Insoluble fiber
- Soluble fiber can dissolve in water and form gels(high viscous) where insoluble fiber is unable to form gel(less viscous)
- Soluble fiber can be digested by intestinal bacteria but insoluble fiber cannot 😕
In market, people less prefer on high insoluble fiber food because it is poor mouthfeel - dry, dense and rough! 😔how to solve it? Hydrocolloid!
Hydrocolloid
- hydrophillic = bind water ⇨ movement of molecules restricted ⇨ help in thickening & gelling]
- oil binder (depends on fiber used)
- prevent crystallization
- prevent syneresis
- antioxidant properties - prevent oxidative rancidity
Gum
- Fat replacer
- Prevent crystalization
- Extent shelf-life
- Form viscous solutions
- Mostly dont form gel
Guar gum - from seed
- high surface area (may cause lumping)
- can dissolve in cold water
- good stability
example,
act as stabilizer in frozen products (provide smooth texture, prevent crystalization & syneresis)
also in drinks (form homogeneous product, can stand in cold condition, control viscosity)
- good emulsifier
example,
in mayonaise, can act as emulsifier and reduce fat & calorie content at the same time.
- can extend shelf-life
in bakery products, prevent retrogradation ;
in candies, prevent crystalization and control viscosity too.
Xanthan gum - Microbial exudates
- Good suspension & emulsifying property
- Good water solubility (hot and cold water)
- Efficient thickening property
- Good stability to temperature, acid base and salt
- Viscosity unaffected by temperature
example,
yogurt - stabilizer, pH resistance,temperature resistance
tomato sauce - pH resistance, stabilizer
dairy product - additional guar gum will make better result
Agar & Carrageenan - Seaweed exudates
Form Gel!
Agar only can dissolve in hot water
carrageenan can react with protein to aid in stabilization, heat-reversible gel
Pectin
- function as gelling agent, stabilizer and thickening agent.
- classified by the degree of methoxylation (HMP & LMP)
- HMP only need sugar to form gel
- LMP need ion like Ca2+ and acid to lower the pH and form gel
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