Min+Weekly+summary


 * Min Ing's Weekly lecture summary **

Week 1-5

 __ What is Hydrocolloid? __




 * **The term ‘hydrocolloids’ - to aof polysaccharides and proteins (also known as ‘water soluble gums’ or just ‘gums’.) **
 * **Primary functions- Thickening agents, Gelling or texturizing agents **
 * **Secondary functions- Stabilization of emulsions, suspension of particulates, control of crystallisation, encapsulation, formation of film **


 * __Main classes of hydrocolloids __**
 * derivatives from exudation or sap of trees (e.g. cellulose, gum arabic, gum karaya, gum ghatti, gum tragacanth)
 * extract from seed (e.g. guar gum, LBG, tara gum, tamarind gum)
 * extract from seaweeds (e.g. agar, carrageenan)
 * microbial gums (e.g. xanthan, dextrun,curdlan)
 * extract from tubers (e.g. konjac)
 * extract from plant parts (e.g. starch, pectin, cellulose)




 * __Factors affect gum properties __**
 * molecular weight
 * monosaccharide composition
 * <span style="color: #008000; font-family: 'Times New Roman','serif'; font-size: 16px;">type of chains
 * <span style="color: #008000; font-family: 'Times New Roman','serif'; font-size: 16px;">number of side chains
 * <span style="color: #008000; font-family: 'Times New Roman','serif'; font-size: 16px;">distribution of side chains


 * <span style="color: #800080; font-family: 'Times New Roman','serif'; font-size: 18px;">Main Hydrocolloids - Thickeners **
 * 1) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">xanthan gum
 * 2) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">carboxymethylcellulose
 * 3) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">methylcellulose and hydroxypropyl cellulose
 * 4) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">galactomannas (guar and LBG)


 * <span style="color: #4747e0; font-family: 'Times New Roman','serif'; font-size: 18px;">Main hydrocolloids - Gelling agent **
 * __<span style="color: #6666f5; font-family: 'Times New Roman','serif'; font-size: 18px;">Thermoreversible gelling agents __**
 * 1) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">gelatin
 * 2) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">agar
 * 3) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">kappa carrageenan
 * 4) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">iota carrageena
 * 5) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">low methoxy (LM) pectin
 * 6) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">gellan gum
 * 7) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">methyl cellulose and hydroxypropyl cellulose
 * 8) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">xanthan gum and locust bean gum or konjac mannan


 * __<span style="color: #008080; font-family: 'Times New Roman','serif'; font-size: 18px;">Thermally irreversible gelling agents __**
 * 1) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">alginate
 * 2) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">high methoxyl (HM) pectin
 * 3) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">konjac mannan
 * 4) <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">locust bean gum


 * <span style="color: #808080; font-family: 'Times New Roman','serif'; font-size: 24px;">Pectin **
 * <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">derived from peel of citrus fruits, apple pomace, sugar beet, sunflower heads.
 * <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">types of pectin---High methoxyl pectin (HMP), DE> 50%

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> - <span style="color: #0000ff; font-family: 'Times New Roman','serif'; font-size: 16px;">High methoxyl pectin (HMP)
 * <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">DE---58% to 75%
 * <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">to form gel, soluble solid content 55-85%, pH 2.8-3.8. (e.g. jam and jellies)
 * <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">ultrarapid/rapid set (DE as high as 77)---used in jam with whole fruits, to ensure uniform distribution of fruits particles.
 * <span style="font-family: 'Times New Roman','serif'; font-size: 16px;">slow set (DE~58) ---used in very acid fruits such as blackcurrant to avoid premature gelation.

<span style="color: #0000ff; font-family: 'Times New Roman','serif'; font-size: 16px;">Low methoxyl pectin (LMP)

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> - DE < 50% — two sub-groups: Conventional low methoxyl pectin (LMP) and Amidated low methoxyl pectin (ALMP)

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> - Form gels in the presence of Ca2+, with a low solids content & wide pH range (1-7) [but soluble solids can be up to 85%]

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> - LMP – less Ca2+ reactive than ALMP <span style="font-family: 'Cambria Math','serif'; font-size: 16px;">⇒ <span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> used as a thickening agent in yoghurt fruit

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> - ALMP – very Ca2+ reactive <span style="font-family: 'Cambria Math','serif'; font-size: 16px;">⇒ <span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> assist gelation in low sugar fruit preparations, e.g. low-sugar jams & jellies



<span style="font-family: 'Times New Roman','serif'; font-size: 16px;">- Carrageenan is a highly refined extract of seaweed from the rhodophyta family.
 * <span style="color: #185e5e; font-family: 'Arial','sans-serif'; font-size: 24px;">Carrageenan **

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> - Chemically its composition is a long chain of galactose residues linked, resulting in a long chain of high molecular weight.

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> **a) Iota Carrageenan** - It is extracted from //Eucheuma Spinosum// seaweed.

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> **b) Lambda Carrageenan** - It is extracted from //Gigartina//, //Iriadeae// and //Chondrus crispus// seaweed.

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> **c) kappa Carrageenan -** It is a extracted from //Eucheuma cottonii// and from //Chondrus crispus// seaweed.



<span style="font-family: 'Times New Roman','serif'; font-size: 16px;">- Derived brown seaweed (Laminaria hyperborea)
 * <span style="color: #c95f5f; font-family: 'Times New Roman','serif'; font-size: 24px;">Alginate **

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> - Made up of blocks of Dmannuronic acid (M-blocks) & Lguluronic acid (G-block)

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> - Alginate gels are heat- and freeze/thaw-stable, and can be prepared at very low solids and low temperatures with moderate shear.

<span style="font-family: 'Times New Roman','serif'; font-size: 16px;"> - Alginates work well as stabilizers in a wide variety of food applications, and are particularly useful in the formulation of restructured fruits and vegetables.



<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- Derived from guar ( <span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 11.3333px;">Cyamopsis tetragonolobus <span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">) seeds, this long, rigid, linear molecule of beta-1,4-D-galactomannans with alpha-1,6-linked D-galactose.
 * <span style="color: #8e5fc9; font-family: 'Times New Roman','serif'; font-size: 24px;">Guar Gum **

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- This galactomannan is soluble in cold water, hydrating quickly to produce viscous pseudoplastic solutions that, although shear-thinning, generally have greater low-shear viscosity than other hydrocolloids.

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- It is stable over a wide pH range, but will degrade at pH extremes at high temperature. The molecules’ interfacial binding allows guar to act as an emulsifier.

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- Guar gum binds water and retards ice-crystal growth.

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- An exudate from the <span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 11.3333px;">Acacia senegal <span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">tree, gum arabic is comprised of arabinogalactan and a lesser amount of polysaccharide/ protein complexes.
 * <span style="color: #5f7fc9; font-family: 'Times New Roman','serif'; font-size: 24px;">Gum Arabic **

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- It is very water-soluble (except at a pH lower than 3), compatible with high solids and provides low viscosity with Newtonian flow at concentrations below 40%.

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- Its applications include encapsulating flavors, emulsifying beverages, clarifying wine, coating candy shells and controlling water.

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- Gum acacia seyal comes from the Acacia seyal tree and is used for coatings and encapsulation.

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- Also called carob gum, as it’s derived from carob (Ceratonia siliqua) seeds, locust bean gum (LBG) has an irregularly shaped molecule with branched beta-1,4-D-galactomannan units. - This neutral polymer is only slightly soluble in cold water; it requires heat to achieve full hydration and maximum viscosity.
 * <span style="color: #106666; font-family: 'Times New Roman','serif'; font-size: 24px;">Locust Bean Gum **

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- LBG finds use mainly in dairy products, particularly ice cream, where it protects against heat shock and imparts a desirable mouthfeel.

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- It can also act as a binder in meats and stabilize sauces, gravies and dressings.

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- A fermentation product of <span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 11.3333px;">Xanthomonas campestris <span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">bacteria, xanthan gum develops a weak gel for high-viscosity solutions at low concentration that show little effect in the temperature range from 0° to 100°C. It is pseudoplastic (shear-reversible) over broad shear rate and concentration ranges, but imparts a stringy texture.
 * <span style="color: #ff0016; font-family: 'Times New Roman','serif'; font-size: 24px;">Xanthan Gum **

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- Xanthan has excellent solubility in hot or cold mediums, exhibits stability to heat and pH and in the presence of high salt concentrations, and resists many enzymes.

<span style="color: #000000; font-family: 'Times New Roman','serif'; font-size: 16px;">- This gum is often used to thicken and stabilize emulsions, foams and suspensions in applications including sauces and dressings.