Chapter 3.1 Functional roles and interaction of food ingredients in food system

What is carbohydrate?
Carbohydrate are organic compounds occurring in foods and living tissues and including sugars, starch, and cellulose.They contain hydrogen and oxygen in the same ratio as water (2:1) and typically can be broken down to release energy in the animal body. Carbohydrate can be classified into complex carbohydrate ( di-,oli-, & polisaccharide) and also into simple carbohydrate (monosaccharide).

Carbohydrate can be divided into 3 categories in food:
A)Sugar
B)Starch
C)Fiber

A)Sugar

1.Sugar can be divided into monosaccharide and disaccharide from the carbohydrate diagram below.

> The function  of sugar in food:
1) Sweetness
-In terms of sweetness, the sweetness level goes up from lactose, maltose, glucose, fructose and finally fructose as the sweetest.
-The sweetness of the sugar may also be affected by the temperature of the food.

2) Crystallization
-Crystallization is the (natural or artificial) process by which solid forms, where the atoms or molecules are highly organized into a structure known as crystal. In other words, when sugar dissolves, sugar has the ability to crystallize. 
-Factors affecting crystallization and quality of end product:
  a) Water content initiate solution
  b) Rate of crystallization
-Food application:
     a) In cookies: Sugar can contribute crispiness and the snapping mouthfeel at the end                  product. Sugar would also affect the spreading in baking cookies.
     b) In candies: Sugar would give different characteristic in the candy making. By applying          different temperature to the sugar syrup, different characteristic such as thread (230                degrees F), soft ball (234 degree F) and hard ball (250 degree F) can be formed.
-In order to prevent and control crystallization, one can use invert sugar, add a mild acid such as lemon and also add the concentration of sugar.

3) Caramelization & Maillard reaction
-Caramelization is the formation of brown color and desirable flavor. It is the process of breaking down the sugar by high heat. (pyrolisis process). It will also form aromatic molecules.
   *In order to speed up caramelization;
    1) Add: protein (egg,milk), Reducing sugar ( fructose, glucose or lactose)
    2) Remove : water
    3) Increase : temperature and pH
-Maillard reaction is the formation of brown color when the amino acid react with carbohydrate molecules(reducing sugar) and undergo a complex chemical reaction. It will form flavour components furfural and hydroxymethyl furfural (HMF)

4) Humectant / hygroscopicity
-All sugar is hygroscopic. As they have hygroscopic characteristic, they are more attracted to water than proteins, starches & gums.
-Sugar will pull water away from these structures builders.
- Sugar such as brown sugar and icing sugar can have a little effect on the moisture of baked goods & nutritional value.

5) Solubility & texture modification
-The solubility of sugar in water would affect the texture and enhance the mouthfeel.
For example: When a sugar is dissolved in water, the water tends to get sticky and have a viscous characteristic sugar as sugar syrup.(invert syrup; fructose : glucose 50:50)
-Besides that, Brix value is used to measured the percentage of soluble solids in aqueous solution.

6) Fermentation
7) Preservative
8) Flavor enhancer & addictive agent

B) Starch

1. Starch can be divided into amylose and amylopectin

2. Functions of starch in food.
 - thickening ability
The thickening ability of the starch happens when starch is heated in excess water. The water migrate into granules and causes swelling of starch. Eventually, granule rupture, amylose dispersed in solution producing a viscous colloidal state. Thus, controlling the structure and texture in water products.
The process : Gelatinization > Pasting > Gelation > Retrogadation > Syneresis

*Retrogradation :  Starch will crystallize when stored or cooled down at room temperature. It is the result of amylose molecule re-arranging in an orderly fashion. It also reduces the quality of food and is undesirable.
*Syneresis: occurs in low temperature, where water molecule formed on food surface.
> The swelling power of starch can be determined by :
#Size of the granule, (higher size, higher sp) >> molecular weight
#The amount of amylopectin.

 - water binder
The thickening ability and water binder affect food properties in terms of clarity, viscosity, and stickiness.

 - gelling agent
The gel formation occurs after gelatinization as the product is cooled. Gelatinize mixtures may exist in sols or gels.

3.Factors affecting the viscosity of starch sols and gels.
-types of starch
> Amylose have a linear chain, strong films and form firm gel formation. (gelling and firming)
> Amylopectin have branched chain, weak films and is non-jelling to soft.( Gummy and cohesive texture)

-concentration of starch
> Thinner starch paste results wither starch content is decreased or liquids are increased.

-extent of heating
> The viscosity of the product will increase at the end of the cooling phase.

-agitation (increase energy, decrease viscous, increase stirring)
> Agitation is to avoid lumping of starch during cooling.
> However, too much agitation can cause fragmentation, pasty texture and weakened gel structure.

-ingredients
> Ingredients such as sugar, protein & Fat and lemon are ingredients that give negative impact to the viscosity. This is because these ingredients act ( coating, binding or complexes) with the granule for available water.

4. Modified starch (How to control syneresis?<use modified starch)
> Changes by physical/ chemical means are useful in creating special starches of unique characteristic:
          -moisture retention, improve texture, improve cell structure, increase volume, enhance              shelf life.
           A) Physical method: modify starches include extruding, drying by drum or spray and                   heating.
                ~ Pregelatinized starch ( cook up starch/ instant starch)
           B) Chemical modification: modify with acids or other compounds to form esters or                       ethers. (replace some hydroxyl groups)
                ~Crosslinking starch ( high shear, able to stand acidic condition, tolerate high                              temperature and control granular swelling)
                ~Substitution starch ( used in frozen food, increase peak viscosity, lower                                     gelatinization temperature, minimize and prevent syneresis)

5. Resistant starch (RS)
>Starch that is resistant to digestion in the stomach and small intestine. (low-calorie profile)
> it provides low water-holding capacity( does not contribute stickiness and not compete for the water by other ingredients)
> complement to natural fibre and it can be labeled as dietary fibre.


C) Fiber

1. Soluble Fiber is fiber that dissolves in water and form gels (viscous) and easily digested by intestinal bacteria. It lowers blood cholesterol and improves blood glucose control.

2. Insoluble fiber is no-viscous and are not digested by intestinal bacteria. It promotes bowel movements, alleviates constipation and prevents diverticular disease.

3. Hydrocolloids are a heterogeneous group of long chain polymers ( polysaccharides and proteins) characterized by their property of forming viscous dispersions and/ or gels when dispersed in water. The increase in hydrocolloid will increase the affinity for binding water molecules rendering them hydrophilic compounds.
> The hydrocolloid form thickening when they are in the concentrated system. These molecules will begin to come into contact with ea other molecules, thus restricting the movements of the molecules. The transition from free moving molecules to an entangles network is the process of thickening. However, in dilute dispersion, hydrocolloids move freely.

4. Type of hydrocolloid:
> Gums : found in plants, undergo low digestion thus provide low calorie.
-less gel formation, fat replacer, prevent crystallization and extent shelf life.
-thickeners, stabilizers, gelling agent in salad dressing.ice-cream, fruit pieces.
- guar gum (endosperm) - good water solubility, stability, efficient thickening property and high shear rate.( does not form gelling properties): frozen products, drinks, sauces, pastries

-Xanthan gum ( aerobic fermentation) of glucose/sucrose with pure culture. - efficient thickening property, good stability to temperature, acid base and salt, good water solubility and good suspension & emulsifying property. : dairy products. mayo, sauces, pastry, topping

5. Agar and carrageenan
> agar are insoluble in cold water and very soluble in hot water > it form a strong and transparent gel.
> Carrageenan are able to interact with protein to aid in stabilization and are heat reversible.
- it can also combine with other gum, because of its propensity for cross-linking.
- milk products, ice-cream, cheese product, chocolate milk

6. Pectin ( mostly are from citrus and apple pomace peel)
> used as gelling agents, thickeners, and stabilizers
> The gel forming characteristics and properties of pectin can be influenced by the degree of methoxylation
> Ingredients such as sugar and acid can effect the properties.
-sugar will compete with water thus reducing attracting force between the pectin and water molecules.
-acid will increase the pectin-pectin attraction.
*sugar and acid are essential for high methoxyl pectin.