Bryan and Michael Voltaggio: Emulsions and Foams, Science and Cooking Public Lecture Series 2015 | Summary and Q&A

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April 12, 2016
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Harvard University
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Bryan and Michael Voltaggio: Emulsions and Foams, Science and Cooking Public Lecture Series 2015

TL;DR

The Voltaggio brothers demonstrate how to create emulsions and foams in cooking, using techniques and ingredients like yogurt, nitrogen, and hydrocolloids.

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Key Insights

  • 🫢 Emulsions in cooking involve trapping a gas within a liquid or solid, creating foams or aerated textures.
  • ❓ Ingredients like yogurt, nitrogen, yeast, and hydrocolloids are utilized to create emulsions and foams with unique textures and flavor combinations.
  • 🔇 The volume fraction in emulsions affects their properties, with a critical volume fraction of around 64% determining whether they behave like a liquid or a solid.
  • 😒 The use of hydrocolloids, such as xanthan gum and soy lecithin, helps stabilize emulsions and create desired textures.

Transcript

[LIQUID HISSING] MICHAEL BRENNER: So we should start. So it's really a great pleasure today to have the Voltaggio brothers. Clap. [APPLAUSE] It's really awesome. And as you see, they're going to put on quite an exciting show. But before we start, we have a couple of other items of business. And today actually, one of them is here we have Professor ... Read More

Questions & Answers

Q: What is the purpose of adding NO2 to the foam in the cucumber salad?

Adding NO2 gas to the foam helps create air bubbles in the liquid, making it light and fluffy. It prevents the foam from turning into frozen ice cubes and enhances the texture and mouthfeel of the salad.

Q: How is the emulsion in the savory porridge made?

The emulsion in the porridge is made by roasting yeast in brown butter, which accentuates the sauce's aroma and adds a savory element. Soy lecithin and xanthan gum are then used to emulsify and stabilize the sauce, creating a mayonnaise-like texture.

Q: How does the Voltaggio brothers achieve the bubbles in their emulsion sauces?

Using an immersion blender, the brothers agitate the hydrocolloids (soy lecithin and xanthan gum) in the emulsion sauce, creating bubbles and a thicker viscosity. This technique helps suspend air in the sauce and enhances the presentation when plated.

Q: How does the Voltaggio brothers' approach to cooking highlight creativity and scientific understanding?

The brothers showcase how creativity can be applied in the kitchen, transforming traditional dishes by incorporating scientific principles. They experiment with ingredients, techniques, and equipment to achieve unique textures, flavors, and presentations, demonstrating the marriage of science and culinary art.

Summary

In this video, the Voltaggio brothers demonstrate their cooking techniques and discuss the science behind emulsions and foams. They create a cucumber salad with a fluffy yogurt foam and a savory porridge with an emulsified sauce. The use of emulsifiers like xanthan gum allows them to stabilize their sauces and create unique textures in their dishes.

Questions & Answers

Q: What is HarvardX?

HarvardX is the online version of Harvard, which aims to create greater opportunities for learning across various platforms and settings.

Q: How do emulsions and foams work?

Emulsions and foams are created by trapping gas or air inside a liquid or solid. In the case of emulsions, ingredients like oil and water are mixed together using techniques like vigorous shaking or blending. Foams, on the other hand, are created by introducing gas into a liquid or solid through methods like whipping or using nitrous oxide (NO2).

Q: What is the volume fraction of the droplets in mayonnaise?

The volume fraction of the droplets in mayonnaise is approximately 64%, which means that 36% of the space is free (air).

Q: Can mayonnaise be considered a solid or a liquid?

Mayonnaise can be considered a solid, although it is not a very strong one. Its solid-like properties come from the presence of droplets (the oil and water) which are packed together in the emulsion.

Q: How are the cucumbers prepared for the cucumber salad?

The cucumbers are vacuum-packed to remove excess air and then cut into oblique pieces. This process helps to change the texture of the cucumbers and intensify their flavor.

Q: How is the emulsion sauce for the savory porridge made?

The emulsion sauce for the savory porridge is made by blending roasted yeast and brown butter together. Xanthan gum is added as a stabilizer and thickener, resulting in a creamy and flavorful sauce.

Q: What is the purpose of using xanthan gum in emulsions?

Xanthan gum is used as a stabilizer and thickener in emulsions. It helps to create a stable and smooth texture in the emulsion, making it easier to work with and ensuring that the ingredients do not separate.

Q: How do the Voltaggio brothers make egg yolk gnocchi?

The Voltaggio brothers make egg yolk gnocchi by cooking egg yolks sous vide at a specific temperature, then blending them with olive oil to create a pudding-like consistency. The gnocchi are formed by piping the mixture into hot water and poaching until they are cooked through.

Q: How do emulsifiers like xanthan gum help in creating sauces?

Emulsifiers like xanthan gum help stabilize emulsions and sauces by preventing the separation of fat and liquid. They also contribute to the viscosity and mouthfeel of the sauce, resulting in a smooth and creamy texture.

Q: What is the key temperature for making emulsions?

Understanding temperature is crucial in making emulsions. Different temperatures can affect the stability and texture of the emulsion, and finding the right temperature is important for achieving a successful result.

Q: How do the Voltaggio brothers use xanthan gum to stabilize their lobster sauce?

The Voltaggio brothers use xanthan gum to thicken and stabilize their lobster sauce, which is made from roasted lobster shells. By adding xanthan gum, they can create an emulsion without the need for extensive reduction, allowing them to have a rich and flavorful sauce without excessive cooking time.

Takeaways

In this video, the Voltaggio brothers demonstrate their culinary techniques and discuss the science behind emulsions and foams. They showcase how emulsions can be stabilized using emulsifiers like xanthan gum, allowing for greater control over the texture and stability of sauces. By understanding the principles of emulsification and the effects of temperature and ingredients, chefs can create innovative dishes that have unique textures and flavors.

Summary & Key Takeaways

  • The Voltaggio brothers showcase their culinary skills by creating emulsions and foams in their dishes.

  • They explain the science behind emulsions and the use of ingredients like yogurt, nitrogen, yeast, and hydrocolloids.

  • The first dish is a cucumber salad with a frozen yogurt foam, demonstrating the trapping of gas within a liquid or solid.

  • The second dish is a savory porridge with a yeast and beer emulsion, using hydrocolloids to stabilize and thicken the sauce.

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