Food Texture and Mouth Feel | Lecture 5 (2011) | Summary and Q&A

October 12, 2011
Harvard University
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Food Texture and Mouth Feel | Lecture 5 (2011)

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This video is a lecture on the science behind mouthfeel and texture in cooking, specifically focusing on the role of polymers in thickening ingredients. The speaker discusses the concepts of elasticity and viscosity and explains how polymers can control both properties. The speaker also showcases examples of different types of polymers, such as starches and proteins, and demonstrates how they can be used to manipulate the texture and mouthfeel of food. Following this lecture, the video transitions to a presentation on the cocktail program at a progressive cocktail bar called The Aviary, which incorporates science and technology in creating unique and immersive drinking experiences.

Questions & Answers

Q: What are polymers and how are they used in cooking?

Polymers are long, flexible molecules that can be found in various food ingredients, such as sugars, starches, and proteins. In cooking, they are used as thickeners to manipulate the texture and mouthfeel of food. When added to a fluid, polymers spread out and form a network through bonding. This network gives the material its elastic properties and can turn a fluid substance into a solid or viscous one.

Q: How do polymers affect the elasticity and viscosity of food?

Polymers play a crucial role in determining the elasticity and viscosity of food. Elasticity refers to the ability of a material to return to its original shape after being deformed, while viscosity refers to how easily a material flows. Polymers create a network structure that holds the material together and gives it elasticity. The more polymers present, the more elastic the material becomes. Additionally, polymers increase the viscosity of a substance, making it thicker and more resistant to flow.

Q: What are some examples of common polymers used in cooking?

Common polymers used in cooking include polysaccharides like sugars (glucose, sucrose), starches found in wheat and potatoes, pectins, and gums. These polymers can form long, flexible chains that contribute to the desired texture and mouthfeel of food. For example, cornstarch contains granules that release polymers when mixed with water, resulting in a thickening effect. Gelatin, a protein-based polymer, forms a network when heated and unfolded, creating a gel-like consistency.

Q: How do shorter polymers differ from longer polymers in terms of entanglement and texture?

The length of polymers affects their entanglement and, consequently, the texture of the material they are used in. Longer polymers have a higher tendency to become entangled, forming a network structure that imparts elasticity and viscosity. Shorter polymers do not entangle as much and have less impact on the overall texture. Longer polymers are preferred for achieving the desired texture, while shorter polymers may be used for different purposes or in recipes that require a different mouthfeel.

Q: How can the elasticity of polymers be understood from a molecular perspective?

The elasticity of polymers can be understood based on the concept of entropy and the multitude of possible configurations that the molecules can adopt. When a polymer is stretched, its possible configurations are reduced, resulting in stored energy. This stored energy behaves similar to a spring. By considering the energy and length scale of the polymer, its elasticity can be calculated using the formula elasticity = thermal energy / length cubed. This understanding allows us to model the elastic behavior of the polymer network.

Q: What factors contribute to the viscosity of a substance containing polymers?

The viscosity of a substance containing polymers depends on the interplay between elasticity and relaxation time. The concentration and length of the polymers affect their entanglement and, in turn, the viscosity. The more entangled the polymers are, the higher the viscosity of the substance. The relaxation time, or the time it takes for the polymers to rearrange when a force is applied, also influences viscosity. Higher elasticity and longer relaxation time contribute to increased viscosity.

Q: How does The Aviary incorporate science and technology into its cocktail program?

The Aviary, a progressive cocktail bar, applies the principles of science and technology in creating unique drinking experiences. The bar treats cocktails as dishes and uses ingredients creatively, thinking beyond traditional glassware and liquid-based drinks. They have eliminated the traditional bar setup and instead use stations similar to a kitchen, where cooks prepare the cocktails. The bar also collaborates with a designer, Martin Castner, to create custom service pieces that enhance the presentation, aroma, and overall experience of the cocktails.

Q: How does The Aviary use different kinds of glassware and service pieces to enhance the cocktail experience?

The Aviary challenges the notion that cocktails must be served in traditional glasses. They have custom-made glassware and service pieces designed by Martin Castner to enhance the overall cocktail experience. For example, they use a piece called the Porthole, which infuses the cocktail with various botanicals and spices, and a light bulb-shaped glass that contains a ginger snow cocktail. The bar also uses unique drinking vessels, such as the Plan and the Cloche, to capture aromas and enhance the sensory aspects of the cocktails.

Q: How does the use of innovative techniques and ingredients create unique cocktails at The Aviary?

The Aviary pushes the boundaries of mixology by incorporating innovative techniques and ingredients. They utilize a rotovap or a distiller to create unique flavors and infusions, such as clear root beer and clear vanilla. They experiment with different textures, such as the fluffy ice made with ginger snow, and play with aromas using smoke or vapor techniques. The bar also combines unexpected ingredients and flavors to create surprising and memorable drinking experiences.

Q: How does The Aviary make cocktails more engaging and immersive for the guests?

The Aviary aims to create an immersive and engaging cocktail experience for its guests. They accomplish this by involving the guests in the preparation and presentation of the cocktails. For example, guests may be given a task, such as swizzling their own cocktail using a lemongrass swizzle stick or pouring a tableside infused cocktail from a porthole. The bar also uses custom drinking vessels and service pieces that capture and enhance the cocktail's sensory elements, making it more interactive and memorable.


The lecture provided an understanding of how polymers, such as starches and proteins, affect the texture and mouthfeel of food. Polymers create a network structure that contributes to the elasticity and viscosity of a substance. Different types of polymers have varying entanglement capabilities, leading to different textural properties. The Aviary showcased a progressive approach to mixology by incorporating science, technology, and innovative techniques in their cocktail program. They challenged traditional ideas of glassware and presentation, creating immersive and unique drinking experiences. By involving guests in the cocktail preparation and utilizing custom service pieces, The Aviary aimed to enhance both the aesthetic and sensory aspects of cocktails.

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