TLE COOKERY 10 Lesson 2 LO1 PREPARE CEREAL & STARCH Sources of Starch

TLE Philippines by Mylene Huliganga

9 Aug 202013:09

Summary

TLDRThe video lesson focuses on the preparation of cereals and starch dishes, highlighting sources of starch from plants, including cereal grains, roots, and tubers. It explains the types and classifications of starches—native, modified, and purified. The lesson covers the molecular structure of starch, including amylose and amylopectin, and their roles in cooking. Key reactions such as gelatinization, retrogradation, and dextrinization are discussed, along with the functional properties of starch in food preparation. It emphasizes the nutritional value of cereals and their importance in a balanced diet.

Takeaways

🌾 The main sources of starch come from seeds, roots, and tubers, including cereal grains (corn, wheat, rice, etc.) and tubers like potatoes and cassava.
🧬 Starches are composed of two fractions: amylose (contributes to gelling) and amylopectin (contributes to thickening).
🥔 Starches can be classified into native starches (naturally derived), modified starches (chemically altered), and purified starches (separated by wet milling).
🍚 Native starches are found naturally in plants, while modified starches are chemically altered to change their properties.
🔬 Starch molecules are polysaccharides made up of glucose molecules. The organization of these molecules in starch granules creates crystalline patterns observed under polarized light.
🍮 Gelatinization is the process where starch granules swell and absorb water, increasing viscosity as starch breaks down when heated.
🍯 Sugar influences the gelatinization process by competing for water, which affects the texture and structure of starch-based foods.
🍽️ Starch has many functional roles in food, such as acting as a thickener, binder, stabilizer, moisture retainer, and fat substitute in processed foods.
🍞 Dextrinization is the process where starches break down into dextrins during dry roasting or heating, such as in toasted bread or sauces.
🌾 Cereals, especially whole grains, provide essential nutrients like carbohydrates, proteins, fats, vitamins, and minerals, and enriched cereals offer added vitamins and minerals.

Q & A

What are the common sources of food starch?
-The common sources of food starch include cereal grains such as corn, wheat, rice, sorghum, and oats, as well as roots and tubers like potatoes, sweet potatoes, arrowroot, and cassava (tapioca).
What is the difference between native starch and modified starch?
-Native starch refers to starch as it is naturally derived from its plant source, while modified starch has been altered physically or chemically to change its key chemical or physical properties.
How is purified starch obtained?
-Purified starch is obtained from grains and tubers through a process called wet milling, which uses grinding, screening, and centrifuging to separate starch from fiber, oil, and protein.
What are the two main fractions of starch molecules?
-The two main fractions of starch molecules are amylose, a long chain-like structure responsible for gelling characteristics, and amylopectin, a highly branched molecule that contributes thickening properties but does not form a gel.
How do starch granules behave when heated in water?
-When heated in water, starch granules undergo gelatinization, where they absorb water, swell, and disrupt their organized structure, increasing the mixture’s viscosity.
What is retrogradation in the context of starch?
-Retrogradation is the process where starch molecules, particularly amylose, reassociate into an ordered structure after gelatinization, resulting in a crystalline texture.
What is dextrinization, and how is it achieved?
-Dextrinization is the process of forming dextrins, which are partially hydrolyzed starches. It is typically achieved by dry roasting starches, such as toasting flour or bread.
How does sugar affect starch gelatinization?
-Sugar influences the temperature and rate of gelatinization by competing with starch for water, which can slow down or alter the process.
What are the functional roles of starch in food?
-Starch functions as a thickener, moisture retainer, binder, stabilizer, and fat substitute in foods. It is used in products like gravies, sauces, processed meats, and puddings.
What nutritional value do cereals provide?
-Cereals provide carbohydrates, protein, fats, vitamins, minerals, water, and cellulose. Whole grains, in particular, are important for a balanced diet and contribute valuable nutrients like thiamine, niacin, riboflavin, and iron.

Outlines

00:00

🌾 Introduction to Starches and Their Sources

This paragraph introduces the lesson on cereals and starch dishes. It explains that starch is mainly found in seeds, roots, and tubers, with common sources being cereal grains like corn, wheat, and rice, as well as tubers such as potatoes, sweet potatoes, and cassava. The paragraph also distinguishes between different types of starches based on their plant sources, and introduces native or natural starches, modified starches, and purified starches, discussing their methods of processing and uses in food preparation.

05:03

🔬 Starch Composition and Molecular Structure

This section delves into the composition and structure of starch molecules. It explains that starch is a polysaccharide made of glucose molecules, and it contains two main fractions: amylose, which has a linear structure and contributes to gelling properties, and amylopectin, which has a branched structure and affects the thickness of starch mixtures. The paragraph also discusses the role of these molecules in the formation of starch granules and their physical characteristics, such as their arrangement in plants and the phenomenon of birefringence when observed under polarized light.

10:06

🥄 Properties and Reactions of Starch

This paragraph explores the various reactions and properties of starch when subjected to different processes. It explains gelatinization, the swelling of starch granules when heated in water, and how viscosity increases as more starch molecules break down. It also introduces retrogradation, the reordering of starch molecules after gelatinization, and dextrinization, the process of forming dextrins through roasting. The paragraph also covers hydrolysis, which occurs during cooking or chemical reactions involving water, and how it affects the viscosity and texture of food.

🍞 Functional Properties and Uses of Starch

The final paragraph outlines the functional roles of starch in food preparation, including its use as a thickener, colloidal stabilizer, moisture retainer, and fat substitute. Starch also enhances the flavor and texture of processed meats and serves as a binder and filler in foods like hot dogs and sausages. The section emphasizes the nutritional value of cereals, particularly whole grains, which provide essential vitamins and minerals, and advocates for including at least four servings of grains in a daily diet. It concludes by highlighting the importance of enriched and restored cereals as nutrient-dense food options.

Mindmap

Keywords

💡Starch

Starch is a polysaccharide composed of glucose molecules, and is a key carbohydrate found in many plants. It serves as a major energy source in human diets and can be derived from cereals, roots, tubers, and legumes. In the video, starch is discussed in detail, with emphasis on its sources, types, and various applications in cooking and food preparation.

💡Amylose

Amylose is a linear chain of glucose molecules found in starch. It contributes to the gelling properties of starch when cooked and cooled, allowing the mixture to hold its shape. In the video, it is explained how amylose plays a role in the structure of starch and contributes to the formation of gels in food such as puddings.

💡Amylopectin

Amylopectin is a branched form of starch, consisting of glucose molecules. Unlike amylose, it does not contribute to gelling but rather to thickening properties. In the video, the distinction between amylose and amylopectin is made clear, with amylopectin contributing to the thickness of starch-based mixtures during cooking.

💡Gelatinization

Gelatinization refers to the process that occurs when starch granules are heated in water, causing them to swell and lose their organized structure. This transformation leads to the thickening of food mixtures. The video emphasizes how gelatinization is an essential process in cooking with starches to achieve desired textures in sauces and gravies.

💡Retrogradation

Retrogradation is the process where starch molecules, particularly amylose, re-associate after gelatinization, forming a more ordered structure. This results in a firmer texture and can cause staling in baked goods. The video explains how retrogradation can affect the texture of food products like breads and pies as they cool.

💡Cereals

Cereals refer to grains such as wheat, rice, corn, and oats, which are staple sources of carbohydrates. The video highlights cereals as a primary source of starch in the human diet, as well as their health benefits and their use in various processed food products.

💡Modified Starch

Modified starches are starches that have been chemically or physically altered to enhance certain properties, such as thickening, stability, or texture. In the video, modified starch is discussed in contrast to native starch, showing how modifications improve its performance in industrial food production.

💡Dextrinization

Dextrinization is the process of breaking down starch into smaller dextrin molecules, usually by dry heating. This process results in a change in color and flavor, as seen in toasted bread or roasted flour. The video explains this reaction as a common culinary technique used to enhance flavor and texture in baked goods.

💡Syneresis

Syneresis refers to the expulsion of water from a gel, often seen when a starch-based gel is cut or left to stand. It is commonly known as 'weeping,' and the video describes how this phenomenon occurs in foods like custards, jellies, and puddings.

💡Hydrolysis

Hydrolysis is a chemical reaction where starch molecules are broken down into simpler sugars in the presence of water. This process can be accelerated by heat and acidity, leading to a reduction in the thickness of starch-based mixtures. The video uses the example of cooking acidic foods like pineapple pie to explain how hydrolysis can impact the texture of pie fillings.

Highlights

The parts of plants that store most starch are seeds, roots, and tubers. Common sources include cereal grains like corn, wheat, rice, sorghum, and oats, as well as roots like potatoes and tropical cassava.

Starches are named after their plant sources: corn starch from corn, rice starch from rice, and tapioca from cassava.

Native or natural starches refer to starches as originally derived from their plant source, whereas modified starches are chemically or physically altered to change properties.

Purified starch is separated from grains and tubers by a process called wet milling, which uses grinding, screening, and centrifuging techniques.

Starch is a polysaccharide made of hundreds or thousands of glucose molecules. The two main types of starch molecules are amylose and amylopectin.

Amylose is a linear molecule that contributes to gelling characteristics in cooked and cold starch mixtures.

Amylopectin has a branched structure and contributes to thickening properties when starch is cooked in water, though it does not form a gel.

Most natural starches are mixtures of amylose and amylopectin. Cereal starches contain higher amylose content than root starches like tapioca and potato.

The starch granule has a crystalline-like structure observed under polarized light. This phenomenon is called birefringence, which disappears when the starch is heated.

Gelatinization is the process of starch granules swelling as they absorb water, causing changes in their structure during heating.

Viscosity increases as gelatinized starches break and release more molecules, thickening the mixture.

Retrogradation occurs when starch molecules, particularly amylose, reassociate into a crystalline structure after being disrupted by gelatinization.

Dextrinization is the process of forming dextrins by dry roasting starches, commonly seen in toasting bread or flour.

Starches act as thickeners, stabilizers, moisture retainers, binders, and fat substitutes in various food products like gravies, sauces, processed meats, and sausages.

Whole grain cereals provide essential nutrients like carbohydrates, protein, fats, vitamins, and minerals. At least four servings of whole grains should be consumed daily for optimal health.