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Questions and Answers
The water attracted to polysaccharides when they are hydrated will freeze at -18°C.
The water attracted to polysaccharides when they are hydrated will freeze at -18°C.
False (B)
What is the primary characteristic of polysaccharides that makes them beneficial in frozen foods?
What is the primary characteristic of polysaccharides that makes them beneficial in frozen foods?
The ability to attract water that remains unfrozen at low temperatures.
Which factor is responsible for the strength, insolubility, and resistance to breakdown of cellulose?
Which factor is responsible for the strength, insolubility, and resistance to breakdown of cellulose?
The ______ of a polymer solution is a function of the size and shape of its component molecules.
The ______ of a polymer solution is a function of the size and shape of its component molecules.
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Match the following polysaccharide characteristics with their corresponding properties:
Match the following polysaccharide characteristics with their corresponding properties:
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Why are enzymes generally unable to break down cellulose efficiently?
Why are enzymes generally unable to break down cellulose efficiently?
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How do polysaccharides affect the texture and properties of food products?
How do polysaccharides affect the texture and properties of food products?
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Polysaccharides are only effective as thickeners or gelling agents at high concentrations (above 1%) in food formulations.
Polysaccharides are only effective as thickeners or gelling agents at high concentrations (above 1%) in food formulations.
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What are the factors that influence the viscosity of a polysaccharide solution?
What are the factors that influence the viscosity of a polysaccharide solution?
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Gels are three-dimensional networks of connected molecules that entrap a large volume of continuous fluid.
Gels are three-dimensional networks of connected molecules that entrap a large volume of continuous fluid.
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What are the two main characteristics of gels that make them distinct from pure solids or liquids?
What are the two main characteristics of gels that make them distinct from pure solids or liquids?
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Polysaccharides can be broken down during heating at lower ______ levels (pH 4.0 or less).
Polysaccharides can be broken down during heating at lower ______ levels (pH 4.0 or less).
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What are some of the negative effects of polysaccharide hydrolysis and attack?
What are some of the negative effects of polysaccharide hydrolysis and attack?
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Match the following characteristics with the correct category:
Match the following characteristics with the correct category:
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Why is it vital for processors to be aware of potential quality and food safety issues related to gums and gelling agents?
Why is it vital for processors to be aware of potential quality and food safety issues related to gums and gelling agents?
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Starch is an important source of energy for humans, accounting for approximately 70-80% of the global human caloric intake.
Starch is an important source of energy for humans, accounting for approximately 70-80% of the global human caloric intake.
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Which of the following is NOT a factor that affects the rate of the Maillard reaction?
Which of the following is NOT a factor that affects the rate of the Maillard reaction?
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The Maillard reaction is an enzymatic browning process.
The Maillard reaction is an enzymatic browning process.
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What is the name of the amino acid that is particularly affected by the Maillard reaction?
What is the name of the amino acid that is particularly affected by the Maillard reaction?
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The browning of baked goods in the oven is an example of a ______ reaction.
The browning of baked goods in the oven is an example of a ______ reaction.
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Match the following browning reactions with their descriptions:
Match the following browning reactions with their descriptions:
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Starch granules are soluble in cold water.
Starch granules are soluble in cold water.
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What are the two main polymers composing starch granules?
What are the two main polymers composing starch granules?
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What process does starch undergo when heated?
What process does starch undergo when heated?
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The initial temperature of gelatinization depends upon the starch/water ratio, [BLANK] , and the degree of heterogeneity among the granule population.
The initial temperature of gelatinization depends upon the starch/water ratio, [BLANK] , and the degree of heterogeneity among the granule population.
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Match the following starch granule characteristics with their impact on the gelatinization process:
Match the following starch granule characteristics with their impact on the gelatinization process:
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What can happen if starch granules are subjected to excessive heating?
What can happen if starch granules are subjected to excessive heating?
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Why is mixing of heated starch solutions a delicate operation?
Why is mixing of heated starch solutions a delicate operation?
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The migration of amylose molecules away from the starch granule into the surrounding solution is always beneficial for the finished product.
The migration of amylose molecules away from the starch granule into the surrounding solution is always beneficial for the finished product.
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The viscosity of a starch solution decreases as the starch granules swell.
The viscosity of a starch solution decreases as the starch granules swell.
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The process of starch becoming less soluble as it cools is called ______.
The process of starch becoming less soluble as it cools is called ______.
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What is a potential problem associated with retrogradation in bread?
What is a potential problem associated with retrogradation in bread?
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What is the primary way in which glucose syrup is manufactured?
What is the primary way in which glucose syrup is manufactured?
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Match the following starch modifications with their primary purpose:
Match the following starch modifications with their primary purpose:
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Which of these is NOT a potential consequence of starch granule fracture?
Which of these is NOT a potential consequence of starch granule fracture?
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What is the primary difference between unmodified and modified starch?
What is the primary difference between unmodified and modified starch?
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Low moisture dough results in a more elastic product than high moisture dough.
Low moisture dough results in a more elastic product than high moisture dough.
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Which of the following properties can be controlled in starches?
Which of the following properties can be controlled in starches?
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Cold water starches are pre-cooked starches that are soluble in cold water.
Cold water starches are pre-cooked starches that are soluble in cold water.
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Cellulose is a natural component of ____ and ____.
Cellulose is a natural component of ____ and ____.
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What is the primary function of cellulose when added to food products?
What is the primary function of cellulose when added to food products?
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Match the following polysaccharides with their primary applications:
Match the following polysaccharides with their primary applications:
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Which of the following polysaccharides is known for generating the greatest viscosity?
Which of the following polysaccharides is known for generating the greatest viscosity?
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Xanthan gum is a polysaccharide produced by a bacterium found on plant leaves.
Xanthan gum is a polysaccharide produced by a bacterium found on plant leaves.
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What is the polysaccharide called that is produced by Xanthomonas campestris?
What is the polysaccharide called that is produced by Xanthomonas campestris?
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Study Notes
Carbohydrates: Part 2
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Reducing sugars, under certain conditions, can produce brown colours. These colours can be desirable or undesirable.
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Examples of desirable browning:
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Browning of baked goods in the oven.
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Examples of undesirable browning:
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Browning of stored sugar
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Overcooking browning
Maillard Reaction
- This browning reaction is caused by the reaction of glucose with amino groups on protein molecules.
- It is a non-enzymatic browning process.
- It alters proteins, notably those containing the essential amino acid lysine.
- The loss of lysine can be a concern for ensuring nutritional content in food products.
- For example, bread can lose up to 40% of its lysine through this reaction.
Total Maillard Effects
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Factors affecting Maillard reaction:
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Time
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Temperature (increased temp speeds up the reaction)
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pH (increased pH increases the rate, decreased pH slows the rate)
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Fructose, compared to glucose, reacts with protein at a slower rate in the Maillard reaction.
Caramelization
- Caramelization is a reaction that occurs when carbohydrates, especially sucrose, are heated.
- It is a non-enzymatic polymerization.
- Results in characteristic brown color and flavors through linking unsaturated carbohydrate rings.
- The reaction does not involve any C=O bonds.
Polysaccharides
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Polymers of monosaccharides
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Made up of sugar units arranged linearly or branched.
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Most have 200 to 3000 sugar units; some, like cellulose, have 7,000 to 15,000.
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Starch amylopectin contains more than 60,000 sugar units.
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Estimated that 90% of carbohydrate mass in nature is polysaccharide.
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Sometimes referred to as 'glycans'
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If all sugar units are the same, it is a 'homoglycan'.
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Examples: Cellulose, starch amylose, starch amylopectin.
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Cellulose has a linear arrangement of glucose units. Hydrogen bonding between the homoglycans causes the strength and insolubility of cellulose fibers (found in cotton and wood). Enzymes have difficulty breaking down these structures.
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Branched heteroglycans(like Guar Gum, Algins, Locust Bean Gum) typically are more soluble in water compared to homoglycans.
Polysaccharide Solubility
- Polysaccharides have strong affinity for water due to hydroxyl units of the molecules.
- They absorb water and swell; may hydrolyze; hydrated water does not freeze.
- This characteristic is important in avoiding phase separation of solutes in frozen foods.
Starch
- A major plant food reserve.
- Estimated to provide 70-80 % of global human caloric intake.
- In nature, starch appears as granules.
- Granules are insoluble and hydrate only when heated; this makes them easy to transfer and mix.
- Composed of amylose (linear polysaccharide) and amylopectin (highly branched polysaccharide).
- Rice starch granules are the smallest, tuber starch are the largest.
Starch Granule Gelatinization
- Starch granules are insoluble in cold water.
- When heated, starch granules gelatinize which disrupts the molecular order within them due to the water absorption.
- Gelatinization depends on several factors such as Starch/water ratio, Granule type, and Heterogeneity among granule population.
- As water is absorbed, the granules swell and amylose molecules migrate to the surrounding solution, which can create problems for processors.
Starch Hydration Viscosity/Temperature Curve
- Viscosity increases as starch granules swell making it difficult for them to move past each other.
- Excessive heating may lead to starch granule fracture, lower viscosity, water loss and phase separation, and loss of product structure.
Starch Retrogradation and Staling
- The solubility of starch decreases as it cools.
- This process is called retrogradation;
- Problems associated with retrogradation include bread staling, and precipitation in soups and sauces.
Starch Modification
- Modifications lead to more consistent behavioral properties than natural starches regardless of seasonal variations in starch supply.
- This is helpful in the production of pastes and gels from starch.
- Some desirable characteristics of modified starch include:
- Heat tolerance
- Shear resistance
- Introduction of specific functionalities.
- Chemical modifications often involve the hydroxyl groups of the starch molecules using chemical transformations.
- Increased cross-linkages between starch molecules will increase gelatinization temps and viscosity of the matrix
Cold Water Starches
- Gelatinized starches that have been thoroughly cooled.
- Many starch granules are broken allowing fast release of amylose/amylopectin.
- Soluble in cold water, do not require cooking, and have high shear tolerance. Good for dry mixes (e.g. pudding mixes).
Cellulose
- Made of flat linear chains of polymerized glucose, linked by hydrogen bonds, resulting in insolubility in water.
- Cellulose provides structural strength to plant fibers.
- Considered as crude fiber by dieticians and is not digested by humans.
- Used to add bulk to food products like bread, minimal flavour, minimal color change, minimal microbial contamination.
Guar and Locust Bean Gum
- Used as thickening agents; Guar gum produces the highest viscosity among natural commercial gums..
- Found in the endosperm of seeds.
- Locust Bean gum has fewer branched units and works well in combination with other gums.
- Widely used in dairy, frozen food and dessert industry; Guar gum is widely used in ice cream.
Xanthan Gum
- Produced by bacterium Xanthomonas campestris.
- Has a similar polysaccharide chain structure to cellulose.
- Increases viscosity of products it is added to.
- It also shows a synergistic effect with guar gum.
- Soluble in both hot and cold water, constant viscosity over a broad temperature range.
- Ideal for pourable products (like gravy), especially those that are hot or refrigerated.
Carrageenan
- A glycan extracted from red seaweed.
- Increases viscosity of food matrices.
- Forms gels in milk and water and binds to proteins, holding them in suspension.
- Used in the chocolate milk industry to suspend cocoa particles.
- Can also assist in brine absorption in cold processed meats and poultry foods.
- Issues with dissolving in hot acids.
Agar
- Seaweed origin.
- Used as a moisture holder in canned meat products and bakery mixes.
Pectin
- Found in plant cell walls and between the cell walls.
- Commercially obtained from citrus and apple peels.
- Acid resistant and useful in forming spreadable gels.
Dietary Fiber and Carbohydrate Digestibility
- Cellulose (insoluble fiber) and some gums are dietary fiber.
- Some carbohydrates (and their component parts) are broken down in the large intestine and simple sugars are absorbed giving the product a caloric value.
- Dietary fiber has several important effects incl. proper functioning of the intestinal tract, increasing fecal bulk, and increased intestinal throughput.
- It's often thought to lower cholesterol levels and reduce the risk of heart and colon cancer.
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Description
This quiz focuses on the role of polysaccharides in food products, particularly in frozen foods. You'll explore their characteristics, properties, and how they function as thickeners and gelling agents. Understand the factors influencing their viscosity and the challenge enzymes face in breaking down cellulose.
