Gels Flashcards
hydrocolloids.
The term hydrocolloid is derived from the Greek words hydro (water) and kolla (glue) (Wüstenberg, 2015) and simply refers to a substance that forms a gel when combined with water.
benefits of gels
When applied externally, hydrocolloids act as emollients that soften, soothe, and hydrate the skin and mucous membranes.
They hold moisture on the skin’s surface and protect localized tissues, acting as a barrier to environmental pathogens. This barrier quality allows them to hold other herbal constituents on the skin’s surface for a longer period of time, a trait enhanced by suspending astringent herbs in gel solutions; according to herbalists Kerry Bone and Simon Mills, “in modern clinical application, suspensions of decoctions of high-tannin herbs in gum tragacanth or gum arabic can produce impressive healing effects in open wounds and skin lesions” (Bone & Mills, 2013, p.141).
Ultimately, gel formulas are an excellent delivery method for herbs to support many topical conditions, particularly for wound healing and scar repair;
with the addition of antispasmodic and/or anodyne herbs, gels can also be formulated for pain management and nervous system support.
Although they are not technically emulsifiers, as they do not have any lipophilic molecules to bind specifically to oils, hydrocolloids are often used in cosmetic creams to stabilize emulsions, in conjunction with other emulsifying agents (Wüstenberg, 2015).
Different catagories of hydrocolloids
Hydrocolloids are classified into four major groups:
hydrocolloids purely isolated from plants (without chemical modification),
plant-derived hydrocolloids that are chemically modified,
hydrocolloids obtained by fermentation,
hydrocolloids from animal species.
What is the main source of carrageenan extract?
Irish moss (Chondrus crispus): Irish moss is a species of seaweed harvested off of the Atlantic coasts of Europe and North America with small, reddish-purple to reddish-green fronds (“leaves”) that grow in a fan-like manner (Pitchford, 2002). The excellent thickening quality of Irish moss is due to the abundance of the polysaccharide carrageenan within its fronds. Refined and powdered, Irish moss is one of the easier hydrocolloids to source for home use, and requires less powder by weight than some other hydrocolloids to form a firm gel.
What is Xanthan gum derived from
Xanthan gum: Xanthan gum is derived from bacterial fermentation of glucose or sucrose and has been used as a commercial thickening agent since the 1970s (Wüstenberg, 2015). The refined, off-white powder makes gels firm up quickly with the aid of an immersion blender; it works well if added to formulas once they are at room temperature.
What are the 3 categories of hydrocolloids purely isolated from plants (without chemical modification),
- exudates,
- seed flours,
- extracts
What are exudates?
Protective substances deposited in plant’s wounds
Ghatti gum
gum Arrabic
Karaya gum
Tragacanth
What are extracts?
substances that provide structural support
Cellulose Agar -Agar Alginate Carrageenan Furcellaran Larch Arabinogalactan Pectins Starches
What are seed flours?
Reserve polysacherides
Guar gum
locust bean gum
Tara gum
Tamarind seed gum
Which plant derived hydrocolloids are chemically modified?
Amidated pectin Cellulose derivatives Modified starches Propolyne glycol Alginate
Which hydrocolloids are obtained by fermentation?
Curdlan Dextran Gellan Pullulan Scleroglucan Xanthan
Which hydrocolloids are obtainde from animal species
Gelatin
Caseinates
What is gum arabic?
Gum arabic: Gum arabic is sourced from the hardened sap of various tree species; it was originally sourced from Acacia senegal and is also called acacia gum. It is frequently used in foods as a stabilizer and emulsifier, and it is also used as a binder in paints, glues, and glazes. Acacia gum contains the immune-active polysaccharide arabinogalactan, so it could theoretically help enhance immune response through the complement system (Bovo et al., 2016)—though when it comes to gel-making this is mostly just an interesting sidenote, since the amount of acacia gum used is unlikely to have a significant immune effect.
What is Guar gum?
Guar gum (Cyamopsis tetragonoloba): Guar gum is the powdered endosperm from the seeds of the guar or cluster bean, which is often used as a thickener and binder in commercial foods. Like other types of soluble fiber, guar gum acts as a bulking laxative by absorbing water in the gastrointestinal (GI) tract. Consequently, extremely high amounts of guar gum can swell enough as they move through the digestive tract to cause significant digestive problems, which is why there are U.S. Food and Drug Administration (FDA)-mandated limits on the amount of guar gum that can be used in foods (Link, 2017). For most people, small amounts of guar gum are safe and have no side effects, although for those with an especially sensitive GI tract, it may cause gas, bloating, or digestive discomfort (Kresser, 2017).
What is Agar Agar?
Agar-agar: Agar-agar is obtained from the cell walls of some species of red seaweeds, collectively classified as agarophytes. The most common species used to produce agar-agar are species in the Geldium genus, which primarily come from the Pacific coast of the United States, Japan, and Chile (Wüstenberg, 2015). These seaweeds have been used for hundreds of years in China and Japan, serving as thickeners in household cooking, somewhat like gelatin (Pitchford, 2002).
