#go forth and gellify!

[femchef]

So today was the first day back for teachers (semester starts on Monday) and I was going over my notes from one of my classes and picking out things to share with another teacher who’s teaching the same class on one of our satellite campuses -

So anyway, does anyone want to read my lecture notes on thickening agents that I turned into a study guide (I wrote one up during the semester because we didn’t have any previously prepared materials because other instructors just skip or gloss over the chapter but I felt like it was worth the time to focus on the topic and also I’m a Nerd about stuff that makes things gooey).

You know what - I’m just going to post it under a cut below, because it’s fun and also an infodump.

**For context, even though my notes go into more specifics than the required reading, the book for the class is called How Baking Works by Paula Figoni (3rd edition, tbh needs an update but is a good reference), and the link I am telling them to refer to for more information on gelatin that includes conversion charts is here:

Thickening Agents Study Guide

1. Thickening vs. Gelling

1.1. Thickening = moving slowly, viscous, but still some movement while set

1.1.1. Either when sugars and proteins become loosely entangled or when water is absorbed and trapped by swollen starch granules, or when air bubbles in foams or fat droplets in an emulsion slow water movement.

1.2. Gelling = completely set, no movement whatsoever

1.2.1. When water and other molecules are prevented from moving around at all, usually when sugars and proteins bond or tightly entangle and form a larger network that entraps water and other molecules.

1.3. A number of thickening/gelling agents are interchangeable in different quantities.

2. Food-Grade Gelatin (Type A Gelatin) is produced by boiling or soaking pigskins in acid; the connective tissue breaks down into thick strands of collagen and thinner strands of gelatin

3. Powdered Gelatin is made from lower-grade pulverized sheets

4. For more information, take some time to view the attached link in blackboard and the conversion charts.

5. Vegetable Gums = polysaccharides that absorb large quantities of water and swell to produce thick liquids and gels. Veg Gums are a nice source of dietary fiber (think fiber one Powder added to drinks)

5.1. Pectin = present in all fruits

5.1.1. LM (low Methoxyl) Pectin = Also comes from citrus peels or apple. Used in low-calorie jams and jellies, relies on calcium rather than sugar to solidify. Suitable for dairy-based products. Becomes increasingly firm as calcium is added until it reaches saturation point, at which time it begins to reverse in process and soften.

5.1.2. HM (high Methoxyl) Pectin = Comes as Rapid Set or Slow Set; extracted from citrus fruit peels. Rapid-Set for products that require suspension; Slow-Set for recipes that require a smooth texture with no suspension (such as a jelly)

5.1.3. NH (Thermal Reversible) Pectin = Modified LMP; Requires sugar and acidity to gel (and less calcium), and can be melted, set and remelted – requires heat to activate properly. ‘NH’ because of the Ammonia Hydroxide treatment it receives to modify (NH3(aq))

5.1.4. Apple Pectin = Derived from apples. Usually sold as a powder, can be used as a gelling and thickening agent, as well as a stabilizer. Is high in healthy carbs, dietary fiber, sodium, manganese, copper, and zinc – which is why it is a common ingredient in health supplements and pharmaceuticals. Additionally used in laxatives for natural purgative qualities.

5.2. Agar = Is a polysaccharide extracted from either of two varieties of red algae (ogonori and tengusa); has gelling/setting properties that behave remarkably like animal protein. Less agar is required than gelatin, and agar has the benefit of holding shape at room temperature. Cannot be used to stabilize aerated products, and does not whip well.

5.3. Carrageenan = a family of sulphated polysaccharides, name comes from variety of red seaweed found off the Irish Coast termed “Irish Moss”. Typically used in conjunction with meat and dairy products, for which they work particularly well, in large-scale production for stabilization, thickening gelling and texturing.

5.4. Guar and Locust Bean Gum

5.4.1. Guar Gum = Extracted from the endosperm of Guar Beans (legume); does not self-gel like LBG, but is more soluble. Requires high temperatures, high ph and longer times to cause gelling. Low-cost alternative to many other agents and starches, and is 8 times more effective than cornstarch. Used commercially, and stays stable when frozen/thawed.

5.4.2. Locust Bean Gum = Extracted from endosperm of bean on Carob Tree. Dispersible in hot and cold liquid, and converts to gel with addition of minimal amount of sodium borate. Is naturally sweet and is typically used to sweeten foods and as a replacement for chocolate.

5.5. Gum Arabic = Acacia/Senegal/Indian/Sudani Gum = Harvested from Sap of two Acacia Tree Species. Primarily used as a stabilizer (such as in sodas and cosmetics).

5.6. Gum Tragacanth = derived from several species of legumes in the genus Astragalus (Tragacanth, lit. “Goat + Thorn��, which is common name). Largely produced/exported from Iran. Is viscous, odorless, and tasteless water-soluble sap. Traditional binder for pigments in artist’s pastels, and main gum used in fabricated Gumpaste.

5.7. Xanthan Gum = derived from a species of bacteria, Xanthomonas Campestris (same bacteria which causes a variety of plant diseases, such as black rot in brassicas and bacterial wilt in turf grass). Produced via fermentation of glucose and sucrose. Is used to stabilize emulsions (is not an emulsifier in itself). Also helps suspend solid particles in liquids. Commonly used as a thickener in egg white substitutes and to build matrix in gluten-free products where there is no gluten-development.

5.7.1. Shear Thinning/Pseudo-Plasticity: Non-Newtonian behavior of fluids who’s viscosity decreases under ‘shear strain’. Examples Ketchup and Salad Dressing.

5.8. Methylcellulose = “Modified Vegetable Gum” an emulsifier and bulk-forming laxative. Unique property of Setting when Hot and Melting when Cold – commonly used in ice creams for this reason.

6. Starches = Starch molecules are polysaccharides that are arranged in one of 2 ways: either as long, straight chains or as short, but highly branched chains.

6.1. Amylose = long, straight chain starches

6.1.1.  Clouds when cooled

6.1.2.   Firm, heavy-bodied gel when cooled

6.1.3.   Not freezer stable

6.1.4.   Thicker cold than Hot

6.1.5.  Masks flavors

6.2. Amylopectin = short, branched chain starches

6.2.1.   High Clarity

6.2.2.   Thickens, but does not Gel

6.2.3.   Less Likely to weep over time

6.2.4.  Less likely to weep when thawed (more freezer-stable)

6.2.5.  Same thickness hot or cold

6.2.6.  Less likely to mask flavors

6.3. Cereal Starches = extracted from endosperm of cereal grains

6.3.1. Cornstarch

6.3.2. Rice Starch

6.3.3. Wheat Starch

6.3.4. Waxy Maize

6.4. Root Starches = Extracted from roots/tuber plants

6.4.1. Potato Starch

6.4.2. Tapioca Starch

6.5. Modified Food Starches = Starches treated with one or more chemicals to possess more desirable properties or results. (i.e. increased stability with excessive heat/acid, texture, speed of setting)

6.5.1. Corn

6.5.2. Potato

6.5.3. Arrowroot

6.5.4. Tapioca

6.5.5. Waxy Maize (clear and clearer tasting)

6.5.6. Instant Starches = pregelatinized or cold-water swelling (jello cold pudding mix).

6.6. Refer back to previous chapters about gelatinization of starches

6.7. Refer to chart 12.5, pg. 337 for a comparison of properties

Homework: 1-30, Ch. 12