Croustade

Milk Chocolate Praline Croustade

The light and flaky pâte croustade long ago entered my repertoire as a go-to dough preparation for savory tarts. Beyond that, I didn’t think of it much until it resurfaced as a solution to a three-fold ‘problem’, a moment of inspiration:

1. In general, I’m always thinking about reducing sugar where appropriate – not out of altruistic concerns about health and wellness, but rather in service of flavor. While sugar can be a great vehicle for flavor, sweetness can also obscure it.

2. More recently, I’ve also been thinking a lot about ‘reconstruction’. The dominant style of plated desserts these days still seems stuck in the rut of ‘piles of stuff’. It’s a pleasant aesthetic, but I’m starting to feel that it’s too easy. Where can we take it next? How can we put things back together in a way that ‘eats’ better, but also challenges the chef to move beyond this stylistic crutch? How do we clean up our plates and still manage to arrange these flavors and textures in an interesting way?

3. One of my favorite pastry chefs to keep tabs on is Christophe Michalak – like Pierre Hermé, he represents a great balance of contemporary and classic with work that is clean, precise, and to-the-point. About a year back I saw something he referred to as ‘tartelette slim‘ – a seemingly impossible, near-cylindrical tart shell. Here was an idea that both changed the notion of what form a ‘tart’ could be, but also presented an interesting vehicle to re-assemble components in a more ‘constructed’ way.

I never came across a formula for the specific dough Michalak used in his version (to be honest, I didn’t look all that hard), but I knew the challenges would be in finding a way to form the cylindrical shape, and then adapting a typical pâte sucrée/brisée  that would hold its shape in the baking process. I immediately ruled out anything with a substantial amount of sucrose – the appealing tenderness it provides in every other dough would be a serious structural disadvantage here. And then I remembered that  pâte croustade  - it’s capable of being rolled extremely thin, it can be formed into various shapes without shrinking or falling apart, and it’s lack of sweetness also appealed to my flavor forward sensibilities.

Croustade 1

The dough is a bit strange – whereas most flaky doughs require cold temperatures to keep small discrete pockets of fat from coalescing, this dough is assembled with melted butter and warm water. Indeed, the end result of mixing often resembles a broken – if not outright greasy – mass. But it is that very ‘broken quality that creates a fine flaky texture after chilling and sheeting. After a couple of years of not making it, the croustade has re-emerged as one of my favorite doughs to work with.

We used to fashion tiny croustade ‘tacos’ as a canapé at Le Bernardin – draped over stainless steel tubes (cannoli forms, actually) and baked – so the problem of form was also solved. When looking to achieve such geometric precision, the smallest things can throw that precision off; I’ve found that cold working temperature and ample resting between the steps of sheeting, cutting, and baking to be crucial. In addition to exact measurements, another challenge was keeping the cylinders stationary during baking; a tight wrap in foil not only holds the dough in place, but foil cut to a specific length can allow for the slack to rest under the narrow gap between the edges of the dough – this prevents the foil from unraveling and the tube from rolling around in general.

Croustade 2

The first iteration of this ‘tart’ appeared with my collaboration in the kitchen at L2O, with wintertime flavors of citrus and fennel (below). A more recent version forms a vehicle for milk chocolate and hazelnut (above).

Below, the recipe for the base dough, and the general dimensions necessary to produce the thin 3/4 cylinder shells:

Pâte Croustade – Opusculum

Courtesy of L2O

Image Courtesy of L2O

Gelatin

Gelatin

Gelatin – few products are as ubiquitous in the kitchen yet so wrought with confusion and potential for misuse. Whether discussing gelatin in front of students who have had little or no exposure to it, or with seasoned pros who use it every day, I’ve come to realize that a lot of cooks see gelatin – as I did for many years – through a lens of  vague, misleading, or just-plain-wrong information, however well-intended its source. Gelatin serves as a prime example of how subtle nuance with regard to ingredients and how we handle them can either lock us into a state of perpetual frustration or liberate us with better control, refinement, and creativity.  What I will attempt to do here is quickly cover some of the basics gleaned from practical experience, some experimental testing, and a lot of technical reading. As with many aspects of cooking, there aren’t always hard and fast rules or optimal ways of doing things; there is always room here for personal preference. Hopefully with a bit of guided navigation through the complex world of gelatin others can benefit as I have, with a better informed launching point from which to make those choices and explore new territory…

SIX THINGS TO CONSIDER ABOUT GELATIN


1. The word gelatin has its roots in the Latin verb gelāre, to freeze, but  eventually began to refer to any general transformation of a liquid into a solid - gelāta. It’s easy to see how it evolved over the years into terms we use today, such as congeal, heladogelato, and specifically gelée and jelly. It’s believed that the earliest ancient forms of gelatin were not put to use in food per se, but rather as crude glues and adhesives. And though its culinary value became better understood and exploited over the centuries, the commercial gelatin we take for granted today did not begin to appear until the early 19th century. Indeed, most gelled dishes up to that point – savory and sweet – began with calves feet, much like this recipe for blancmange from the classic  1832 cookbook by Eliza Leslie, Seventy-Five Receipts for Pastry, Cakes, and Sweetmeats:

Blancmange - Eliza Leslie, 1832

2. Gelatin is mostly protein, which is derived from collagen, which only comes from animal sources. It’s dry composition is roughly 87-92% protein, 7-12% water, and about 1% ash. The great majority of gelatin is produced from porcine (pork) or bovine (beef) sources – predominately from skins and hides, but also from bones (ossein). A lesser amount is derived from piscine sources (fish skin) – both cold and warm water species – and an even smaller quantity from avian (poultry) sources. Porcine gelatin still tends to dominate much of the worldwide production, especially in Europe, but elsewhere bovine gelatin is increasingly common; piscine and avian sources account for less than 2% of total production. The source of any given gelatin is important for those with dietary restrictions, but uncovering the source can be difficult. Package labeling can be frustratingly minimal, though a bit of internet searching can usually help. Lacking info directly from the manufacturer, we can make a few broad assumptions:

- If one sees ‘Kosher’ or ‘Halal’ labeling, one can assume it is of bovine origin (though I have seen some implausible internet rants that claim otherwise).

- If the gelatin is of European origin, there is good chance it is from a porcine source – strictly based on the numbers and the brands readily available to cooks.

- We can also use the two primary types of gelatin – A and B – in determining the source. Before the extraction process, all raw material for gelatin is treated with either an acid (Type A) or an alkaline (Type B). Most porcine sources undergo acid-treatment (A) and bovine sources with alkaline (B), though that isn’t absolute. Adding to the confusion, sometimes ‘Type A’ is used to imply ‘food grade’, but from a manufacturing perspective, both A and B types can be food grade. Labeling by type is not necessarily definitive of overall quality – beyond this initial acid/alkaline pre-treatment, the production of both types are generally the same, though the properties of Type A and B gelatin can differ slightly in the final product.

- Gelatin can be of mixed sources, as is the case with the widely available Knox brand – its parent company Kraft states that it is a blend of both porcine and/or bovine sources.

- For those looking to bypass mammalian sources altogether, gelatin from warm-water fish  - sometimes referred to as isinglass – can approximate the properties of bovine and porcine of similar strength, though its setting and melting temperatures are generally lower, by a difference of up to 5°C/9°F. Cold-water species of fish gelatins form very weak gels by comparison and on the whole are not considered commercially viable.

- Though perhaps obvious to most, anything labeled ‘vegetable gelatin’ is not made from collagen, but rather one or likely a blend of plant-based hydrocolloids aiming to replicate the unique properties of gelatin.

Grea tLakes Gelatin

3. The most common identifier of gelatin is by its ‘strength’ – a grading system known as the ‘Bloom Scale’. This rating is named for Oscar Bloom, inventor of the gelometer patented in 1925 – an instrument that measured the amount of force needed to deform a gel to a specified degree. Though adapted over time, the same basic mechanism is still used as an industry standard in measuring gel strength: a 6.67% solution of gelatin in water is heated and set at specific temperatures for specific periods of time. The resulting gel is pressed with a cylindrical plunger to a depth of 4mm – and that force, measured in grams, is its Bloom rating. Thus, a gelatin whose tested gel requires 200 grams of force has a strength of 200 Bloom. All commercial gelatin lies within a range of 50 to 300 Bloom, however the range accessible to most cooks is generally narrowed from 125 to 250.

A higher Bloom value generally represents a stronger gel, a higher gelling temperature, a lighter color, and neutral odor/taste – but Bloom strength is not necessarily a complete means of determining a gelatin’s specific properties or purity. But overall quality is also a function of the extraction stage from which the the base gelatin is produced – early extractions of the raw material tend to have higher Bloom ratings than subsequent extractions – which number from three to six – requiring increasing amounts of heat and water to access the remaining protein. I like to think of it like olive oil – the first pressings at lowest temperatures offer the highest quality.

Regrettably, as with animal source, most retail gelatin labeling omits this very important Bloom number.  In its place we see instead a grading system using the names of precious metals (bronze, silver, gold, and platinum) in designating gelatin sheets of different strengths (more on this below). The aforementioned Knox powder does not list a Bloom number on its packaging, however my inquiry to Kraft revealed a ‘target’ Bloom strength of 235 (most sources list it as 225 – close enough – so I will stick to that ’rounded’ figure).

Before moving further – the use of the word ‘bloom’ can be confusing as it is used to refer to two things – a gelatin’s strength, and the initial process of hydrating or soaking in water.

4. Although sheet gelatin of different grades have different weights and different bloom strengths, they are theoretically interchangeable.

To quote Schrieber and Gareis (Gelatine Handbook):

In the case of leaf gelatine, the leaf thickness and hence the weight of the individual leaves is set according to the type of gelatine being processed. Thus, any particular leaf of gelatine dissolved in a given amount of fluid results in the same gelling power, independent of whether ‘‘high-Bloom’’ or ‘‘low-Bloom’’ gelatine is used in the leaf manufacturing process. This principle is valid for both major worldwide manufacturers and hence for all the brands available on the market.

The table below offers an average Bloom strength for each grade of sheet gelatin, its weight, and number of sheets in 1000g, alongside a common 225 Bloom powdered gelatin:

Gelatin Grades

The grade differentiates the gelling ability on a per gram basis, so bronze gelatin actually weighs more than gold yet achieves the same “set”.  For example, in a recipe calling for 2 sheets of silver gelatin, the same gel strength should be achieved by substituting 2 sheets of either bronze or gold grades. Recipes that call for a weight of sheet gelatin without also stating the Bloom strength can cause obvious confusion, as the weight of each sheet changes with an increase in Bloom strength. In such situations, while we might assume a silver grade will produce the desired result, it is often best to prepare small test batches in order to fine tune the formula.

            Converting between sheets and powdered gelatin can be more problematic. Several sources cite the powdered gelatin equivalent of one sheet to be approximately 1 teaspoon; however, volume measurements are not as consistently accurate as measuring by weight, and as we can assume from the table above, 2.3g of 225 Bloom powdered gelatin would most certainly result in a stronger gel than one sheet or 2g of 200 Bloom gold grade gelatin.

            The following conversion formula allows us to use the figures above to more accurately move back and forth between different gelatin grades, or between sheet and powdered gelatin:

The weight of the known gelatin x square root (known gelatin bloom strength/unknown gelatin bloom strength) = weight of unknown gelatin.

 

            For example, a formula calls for 2 sheets of silver grade gelatin (160 Bloom). At 2.5g per sheet, the total weight of the known gelatin is 5g. To substitute powdered gelatin in place of the silver grade sheets:

Weight of known gelatin = 5g

Bloom strength of known gelatin = 160 (silver)

Bloom strength of unknown gelatin weight = 225 (powdered)

160 divided by 225 = 0.71

The square root of 0.71 = 0.84

Multiplying our known weight of silver gelatin by a factor of 0.84 will give us our equivalent weight of powdered gelatin.

5 x 0.84 = 4.2

Thus, 4.2g of 225 Bloom powdered gelatin has the same gelling strength as 2 sheets or 5g of 160 Bloom silver gelatin, or for every sheet of silver, substitute 2.1g of powdered gelatin.

            Or you can save time and use the table below, which calculates this basic formula for substituting between different Bloom strengths by weight from commonly used 140 to 225 Bloom:

Gelatin Conversion

So, given all these options, which gelatin is ‘better’? Some feel that powder is somehow less ‘pure’ than sheets (in reality, all sheets are made from powdered gelatin). Some prefer the convenience of counting sheets over weighing of powder. Some use a specific gelatin for different applications. Some choose based on price (though for a true comparison, it’s best to compare the price per sheet between, say, silver and gold – a 1K box of silver may be cheaper overall, but remember that there are a hundred more sheets in that box of gold). And then some are limited by what is available from their local purveyors, though I’d argue that should no longer be an obstacle to sourcing anything in the age of internet.

5. Gelatin will absorb a fairly constant amount of water – about five times its own weight. So why do we tend to use large amounts of excess water for hydration? For example, one sheet of silver gelatin that weighs 2.5g will absorb about 10 to 12g of water. Because it can be difficult for such a small amount of water to cover the surface area of one gelatin sheet, it makes sense to hydrate the gelatin in a larger amount of water to completely submerge the sheets, and then gently squeeze out any excess water. This practice is perfectly acceptable, though care must be taken in handling the gelatin so that it loses none of its gelling power in the process; common loss can occur when the gelatin breaks into smaller pieces, is hydrated in warm water, or when it is squeezed with warm hands.

Hydration

Ideally gelatin sheets are bloomed in just enough ice water to cover, followed by draining through a sieve with gentle pressure to remove excess water. Excess water that is added to a recipe along with the gelatin will in effect dilute its gelling power. As a measure towards consistency, I have always preferred hydrate gelatin in a measured amount of water (about 5x)  for 10-15 minutes and simply add any excess with the gelatin, having accounted for the water within the recipe. A third method employed by some chefs (and one that I’m playing around with) is to prepare a ‘gelatin mass’ in bulk by hydrating a large amount of gelatin in a precise measurement of water and heating the whole until the gelatin is dissolved; this is further allowed to set, and these chefs’ recipes will then call for a measured weight of the set gelatin mass rather than a number of sheets. Converting recipes that use gelatin mass – and I see more and more of them – can be a pain if the variable includes gelatin of unknown Bloom strength.

Gelatin Mass

Powdered gelatin is hydrated in a similar manner; the gelatin is sprinkled over a small bowl containing 5-10 times its weight of cold water. Sprinkling the gelatin on top of the water will allow it to disperse and absorb water at an even rate – pouring the water over the gelatin will often result in lumps of dry granules that lose access to the water because the surrounding gelatin swells in size as water is absorbed. It is common practice to use water when hydrating either powdered or sheet gelatin, but most liquids are acceptable, as long as they are cold. When converting between sheets and powder, it is important to know that gelatin absorbs about five times its weight in water. That is, 5g of gelatin will absorb 25g of water. While this water is always listed in formulas using powdered gelatin, it is not listed in formulas where sheets are placed in excess water. This difference in water should be considered when converting between sheets and powder.

A couple more general reference points on the behavior of gelatin gels:

- In typical dosages, gelatin begins setting in the range of 15-20°C/60-70°F and melts at just about body temperature, 35°C/95°F. This narrow gap between setting and melting is referred to as hysteresis. Though visible signs of gelling occur rather quickly under refrigeration, it’s important to realize that the complete gel structure  and thus full strength may take up to 12 hours to set.

- Excess heat over extended periods of time can damage gelatin and produce a weaker gel; ideally, gelatin should never exceed temperatures 60°C/140°F.

6. Consider how other ingredients affect gel properties. Let’s take a step back to remember that gelatin is a hydrocolloid – it gels water. Although we set complex mixtures that also contain fats, sugars, and other ingredients, we should be mindful in determining gelatin dosage based on water content. For example, In setting a creme anglaise into a simple cremeux, we should look first at the weight of water, excluding the fat and nonfat solids; further fine-tuning of the gelatin ratio can then be done as one assess how these other factors may affect the gel’s properties, if at all.

A very worthwhile exercise is to set a range of plain water gels of various gelatin types and concentrations –  it’s a valuable exercise to try with all hydrocolloids – one can learn a lot about the subtle differences in products before other factors like fat, solutes, and pH are introduced…

Water Gels

Factors that can affect the properties of gelatin:

- High levels of dissolved sugars or salt can slow the hydration and dissolution of gelatin; because they bind water, the gelatin must compete for available water. However, sucrose and sugar alcohols like sorbitol help stabilize gelatin gels, increasing both the setting time and the melting temperature.

- Fats can soften or ‘plasticize’ gels, which may require a higher dosage of gelatin. On the other hand, similar items that contain solid fats like cocoa butter may require a lower dosage of gelatin, as those fats provide structure of their own.

- Gelatin is stable within a pH range of 5-9 – increasing the acidity can weaken gel strength. For gels with a lower pH, one can simply add more gelatin to compensate, or use a buffering salt such as sodium citrate at roughly 1% of the weight of gelatin.

- Some fruits – such as pineapple, papaya, kiwi, and fig – contain proteolytic enzymes (papain, bromelain) that inhibit proper gelling; using these fruits with gelatin requires prior heating to destroy these enzymes.

- Alcohol will also inhibit gel formation and requires higher concentrations of gelatin to achieve gels comparable to water alone. An intriguing formula and good starting point, for edible cocktails proposed by Martin Lersch of khymos.org% gelatin to add = (% alcohol in final mix x 0.1) + 2

- The synergistic effects of gelatin combined with other hydrocolloids are many; perhaps the best overview of gelling possibilities can be found in Volume Four of Modernist Cuisine.

I think that sets us up for some more in-depth topics in the future, as this only begins to scratch at the surface of gelatin. Below, of many variations of gummy candy that I’ve tried, my current favorite – adapted from a formula taught by Jean-Marie Auboine:

Passion Fruit Gummy Candy – Opusculum

Some invaluable references below on the subject of gelatin:

Gelatine Handbook: Theory and Industrial Practice, by Reinhard Schrieber and Herbert Gareis 2007

Handbook of Food Proteins, edited by G.O. Phillips, P.A. Williams 2011

Handbook of Hydrocolloids, edited by G. O. Phillips and P. A. Williams 2000

Modernist Cuisine, by Nathan Myhrvold, Chris Young, and Maxime Bilet 2011

How Baking Works, 2nd Edition, by Paula Figoni 2010

Gelatin Handbook,Gelatin Manufacturers Institute of America 2012

Chef Steps

And did you know that Kitchen Arts and Letters in NYC now sells books online? Awesome!

Butter

Butter

Though perhaps impractical on a large scale, making butter is a fun process through which we can better understand the wonders of milk. In speaking of butter, it helps to place it context within a broad view of milk and its derivations. All mammals produce milk whose purpose is to feed infant mammals of that species. The same is true of humans, although we didn’t always seem to be hard-wired for consuming milk as adults; in childhood our bodies are supposed to stop producing the enzyme needed to break down lactose – the sugar found in milk. Indeed it is lactose that the dairy intolerant have problems with. Depending on whom you ask, it is believed that an ancient genetic mutation or biological imperative (perhaps vitamin deficiencies due to human migration further away from the equator) led to a growing toleration of lactose well into adulthood, leading to widespread fresh milk consumption in the neighborhood of about 7,500 years ago, if not earlier.

Long before, however, domestication of animals for meat as well as dairy had led to the development of fermented milk products of many kinds – from yogurt to hard cheeses – which were not only easily digestible (bacterial fermentation ‘eats up’ most of the lactose), but nutritious, portable, and stable for longer periods of time. Think about it: fresh milk is highly perishable and made up of 88% water; if you’re a nomadic herder constantly on the move, it makes sense to remove some of that heavy water and concentrate milk’s energy and nutrients, in turn increasing its shelf-life, and in many cases expanding its flavor profile.

Below, an approximate composition for cow’s milk and another that compares it against other mammalian species:

 Composition of Cow's Milk

 Comparison of Mammalian Milk Composition

Not only is the composition important in determining the properties of milk, but looking at the physical structure is also helpful. Milk in its raw form is relatively unstable, in that the milk fat has a tendency to flocculate – to cluster together and rise to the surface. Because of milk fat’s natural tendency to form this ‘cream layer’, most commercial milk products are homogenized in order to separate the fat into small, stable droplets evenly dispersed throughout the product. In a process that has remained fundamentally unchanged for over a century, the milk is pumped through a screen of tiny openings at high pressure and velocity, effectively breaking the individual fat droplets into smaller ones. Homogenization is typically carried out immediately after pasteurization – the process of heat plus time used to destroy harmful microbes.

The structure of milk can be expressed in three different ways:

- An oil-in-water emulsion with the fat globules dispersed in the continuous water phase. An emulsion is an evenly dispersed mixture of two substances that do not readily mix – in this case the milk fat and water. Homogenization of the milk creates this emulsion.

- A colloidal suspension of protein particles; a suspension involves solid particles that are, in effect, ‘floating’ within in the milk.

- A solution of lactose, soluble proteins, minerals, vitamins other components; a solution refers to all of the substances dissolved within the milk.

World Science Festival Butter Lab, 2014

Generally speaking, both the price and perceived level of quality of any dairy product is proportional to the percentage of milk fat it contains. The fat component in milk adds richness, aroma, and flavor to pastry preparations, and can contribute a smooth texture and creamy body, adding a sensation of moisture and lubrication to the palate as it is consumed. In baked goods, milk fat shortens, or tenderizes the finished product. The moisture in butter can create leavening as the tiny droplets turns to steam in the oven. Milk fat can be provided by whole milk, but also from concentrated forms, such as heavy cream and butter. With regard to whipped cream and ice cream, it is the fat that provides their primary solid structure, a ‘scaffolding’ of sorts surrounding air that has been whipped into it.

Below, a table comparing the composition of the most commonly used products derived from milk:

Comparison of Milk Product Composition

On our way to butter, we must also discuss cream – that portion of milk that naturally clusters and rises before homogenization. As mentioned, traditionally this is referred to as the ‘cream layer’ skimmed off of fresh milk. Today, a range of high fat products are produced, tailored for specific uses. Like milk, creams are categorized according to their fat percentage. Below, a table that compares common consumer and commercial products by composition:

Comparison of Cream Product Composition 

 

Heavy cream or heavy whipping cream contains between 35% and 40% fat and is most commonly used in those two forms, providing flavor and texture to pastry preparations. The high fat content provides desirable boiling and whipping properties; the reason why boiled milk forms a ‘skin’ of protein and cream does not is because the extra fat in cream buffers the casein proteins, preventing coagulation when the cream is boiled (there’s also, of course, less protein cream to begin with). The fat also stabilizes whipped cream by forming a continuous, partially coalesced network around air that is whipped in. Because even a 5% difference in fat can adversely affect some delicate preparations, recognizing fat content and being able to adjust a formula is important.

An intermediate along the spectrum of cream and butter is clotted cream – also known as Devon or Cornish cream – a unique high fat product. Clotted cream is cream which has had a portion of its water cooked off, to produce a minimum fat content of 55%, though it can be higher.

           Whipping Cream

As with ice cream, we can better understand butter by first looking at liquid cream’s ability to whip up into a solid foam – an everyday example of shear-thickening. Technically speaking, all foams can be described as colloidal, two-phase systems in which air forms the dispersed phase and water forms the surface phase. In the case of whipped cream, the surface phase contains casein proteins that complex with the partially coalesced fat -destabilized by the physical force of whipping –  forming that ‘scaffolding’ surrounding the air cells that are incorporated during the whipping process.

The two primary factors responsible for cream’s ability to whip are fat content and temperature.A minimum 25% is necessary to create a solid structure. In order for the fat to properly adhere or coalesce, the milk fat within the cream must also be partially solid, or crystalline. Success also depends on a minimum of 5˚C/40˚F. Half and half, for example will never whip up to a solid because it lacks sufficient fat. Likewise, cream that is room temperature or warmer will fail to form a stable structure because a large portion of its milk fat will have begun to liquefy, simply forming larger fat globules rather than a network of small globules that retain some of their own identity.

Counter-intuitively perhaps, whipping cream to ‘stiff’ or firm’ peaks does not necessarily provide for maximum stability and volume of whipped cream. A firm textured whipped cream is a result of too much coalesced milk fat, which will eventually ‘squeeze out’ some of the air and water phases; an unstable, over-whipped cream will likely have a slightly grainy texture, will ‘weep’ water over time, and will be difficult to incorporate into another mixture, such as when using cream to lighten a mousse. Fat coalescence in whipped cream is irreversible, meaning that once adhered, the milk fat cannot be separated without heating and chilling the cream to liquefy and recrystallize the fat. Thus, over-whipped cream can rarely be ‘rescued’; it is often better to use the over-whipped cream for another use and start over, whipping the cream to a ‘soft’ peak for maximum volume and stability.

As noted above, cream can be described as an oil-in-water emulsion with milk fat globules dispersed in a continuous water phase. In whipped cream, that milk fat has partially coalesced to form a semi-solid structure. When the cream is whipped or beaten further, those milk fat globules continue to coalesce – they irreversibly increase in size, expelling much of the air and water phase to eventually form a water-in-oil emulsion where the remaining water is dispersed in a continuous fat phase. This simple inversion of the original cream’s original structure is how butter is produced.

Below, various stages of whipped cream stable soft peak to finished butter.

Whipped Cream, Soft Peak

Whipped Cream, Firm Peak

Whipped Cream, Stiff Peak

Whipped Cream, Broken

Whipped Cream - Coalescence

Early Stage of Butter

Final Stage of Butter

Drained Butter

As more and more of the fat becomes tightly packed together, it is further separated from much the cream’s original liquid, referred to as buttermilk. This buttermilk (a little less than half the original weight of the cream) contains only a trace of the cream’s original fat, but a majority of its nonfat solids. The buttermilk we produce as a byproduct of making butter ourselves is a bit different than the commercial buttermilk available. Although its name survives from the traditional practice of allowing ‘true’ buttermilk to spontaneously ferment, modern commercial buttermilk is produced by inoculating low-fat or skim milk with a bacterial culture (Lactobacillus bulgaricus or Lactococcus lactis), sometimes supplemented with additional nonfat milk solids to create a thicker texture (as in all cultured dairy products, the acids produced by the bacteria denature the proteins, which gives the product body). Even though it differs from the commercial version, the possible uses of fresh buttermilk are many; I recently made a fairly decent ricotta from it, as there remain a substantial amount of curd-forming proteins.

To salt, or not to salt: up to 1.5% salt can be added to butter (at the final kneading stages, otherwise it will dissolve and drain away with the buttermilk) in part for flavor, but traditionally relied upon as a preservative. It is generally preferable to use an unsalted butter, which allows the chef to better control the salt content of a preparation as well as to ensure a fresher product. If I intend to use salt with butter for bread service, I actually prefer to serve it with a sprinkle of coarse Maldon salt at the table.

Federal law requires that butter contain a minimum 80% milk fat. Most commercial butters are composed of roughly 82% fat, 16% water, and 2% nonfat milk solids. High fat butters, sometimes referred to as European-style, may have a fat content of 83% to 84%, and are desirable for their plasticity, especially in the preparation of laminated dough products. A simple means of determining the fat content is to cut a thin slice from the cold butter and try to bend or fold it – a low fat butter will break and feel brittle, whereas a high fat butter will maintain a greater degree of flexibility, even when cold.

A simple method for making cultured-style butter by hand from heavy cream and crème fraiche is given below. The butter-making process is relatively simple; the cream and crème fraiche are whipped until all of the fat has coalesced. The resulting liquid, or butter milk is drained off and further kneaded from the fat. This method can produce a butter of higher fat content more complex flavor than most commercially available butter:

Cultured Butter – Opusculum

Finished Butter, Washed and Kneaded

A few in-depth resources on milk:

On Food and Cooking, by Harold McGee

Milk and Milk Products: Technology, chemistry and microbiology, by A. Varnam and Jane Sutherland

Dairy Science and Technology, by Pieter Walstra, Jan Wouters, and Tom Geurts

University of Guelph (Ontario), Dairy Education Series

https://www.uoguelph.ca/foodscience/dairy-science-and-technology

Also of interest, from my dairy and ice cream guru, Cesar Vega:

The Kitchen as Laboratory: Reflections on the Science of Food and Cooking, by César Vega, Job Ubbink and Erik van der Linden

And did you know that Kitchen Arts and Letters in NYC now sells online? Awesome!

Crunchy Choux

Crunchy Choux

I should probably give pâte a choux a rest – I’ve been off and on obsessed with it for over two years – but I feel there is still much more to harness from this understated preparation and more to refine.  When it’s done well, there are few better pastry-based vehicles. But therein lies the problem: often viewed as ‘just a vehicle’ for whatever is inside of it, we don’t always give it the attention it deserves.

It’s true that the basic ratio of ingredients doesn’t vary all that much, and hasn’t really strayed from that of Carême, who is generally regarded as the author of the modern recipe use today. I went back to the only choux recipe I have in my files from Carême – an 1834 English translation of his Le Pâtissier Royal Parisien - though the quantities are surprisingly imprecise, any novice pastry cook would immediately recognize the general proportions and method:

Royal Parisian Pastrycook and Confectioner, Carême 1834

'Almond Choux' - Carême

Because the standard formula of liquid, fat, flour, and eggs is fairly constant, I get the impression that few chefs ever adapt beyond the first version of the recipe they acquire as a student or young cook. That’s a shame, because there is a lot more about the method to understand and subtle tweaks to fine tune in order to raise the bar for choux… Small adjustments in milk fat and nonfat solids can help determine texture, flavor, and color. Sugars – and sometimes salt – are omitted outright. From cake to bread flour, small adjustments in the overall protein content can affect the final structure and exterior appearance. Time and temperature of the preparation matter at each step – how long to cook the roux, at what temperature should the eggs be added…

I can’t say that I’ve worked through every variation of ingredient and procedure, but I’ve continued to improve my choux slowly but surely over time. A huge revelation came with understanding the best technique for applying a crunchy exterior to the finished piece: a sablée of sorts, but more so in proportions similar to a streusel (roughly equal parts of fat, sugar, and flour) that is ‘tender’ enough to expand with the choux, where a conventional dough would set too quickly and restrict the ‘puff’. In fact, perhaps counter-intuitively at first glance, the sablée- draped choux actually rises up to twice as much as an uncovered one – the sablée slows the drying and setting of the choux surface, allowing it to expand that much more.

Pistachio Choux

Always looking to refine and streamline production along with quality, the crunchy choux also offered a unique efficiency – in part thanks to a push from my friends at the PreGel training center, run by Frederic Monti. Understanding that choux can be frozen before baking as well as after, the choux is piped into silicon molds (perfectly consistent size and shape) and frozen; the sablée is sheeted, cut into discs and draped over the frozen choux domes. The choux is then baked comme d’habitude – high heat to begin for maximum oven spring, with a gradual decrease in temperature to dry out the interior.

Choux Method 1  (Photo Credit - Lauren DeFilippo)

Choux Method 2  (Photo Credit - Lauren DeFilippo)

Choux Method 3  (Photo Credit - Lauren DeFilippo)

Below, the full recipe for the choux and  sablée, with one of my favorite fillings, a chartreuse mousseline:

Crunchy Choux – Opusculum

Finding ultra-technical, underlying science of choux is not as easy as one would think. A few of my favorite general baking science references are:

How Baking Works: Exploring the Fundamentals of Baking Science, by Paula Figoni

Understanding Baking: The Art and Science of Baking,
by Joseph Amendola, Nicole Rees, Donald E. Lundberg

Baking Problems Solved, Stanley Cauvain and Linda Young

Eclairs!, by Christophe Adam

And did you know that Kitchen Arts and Letters in NYC now sells online? Awesome!

Crunchy Choux (photo credit Stephen Kenny)

Pain au Lait

Pain au Lait, Lamination

 

Pain au lait – literally, ‘milk bread’. I first became aware of this soft buttery bread very early on in my career, but it never really entered my repertoire. And then I transitioned into restaurants, and my bread interests were eclipsed by the world of plated desserts. For some fifteen years I just never got much of a chance to exercise those bread skills.

But the urge to put my hands into dough from time to time never went away. It was working with bread that unexpectedly pulled me over to the dark side of professional cooking. It was the sartorial moment I realized bread dough is a living thing; the baker is merely a facilitator, creating the right conditions for a humble lump of flour/water/yeast/salt to transform itself into the very staff of life. The variability of what we can coax from their sum, let alone the fact that it becomes anything edible at all, makes the head spin. It’s easy to imagine, therefore, how a young mind could be seduced by the mechanisms of bread into the wonders of food and cooking at large. As I continued to move away from the day-to-day rigors of the professional kitchen, it made sense in recent months to refresh that repertoire and expand it. When I pick up a smooth ball of dough, sensing its stage of development, shaping it into the loaf it will become, I discover physical memories apart from those of the mind. Just like riding a bicycle, or tying your shoes, your body remembers those movements without thinking. When you fall out of practice with anything, revisiting it feels awkward for a few moments. But it comes back.

 

Pain au Lait, Turns

My interest in pain au lait was rekindled after hanging out in the kitchen at L2O in Chicago, which has perhaps one of the most impressive restaurant bread programs I’ve come across. I struggle to describe the flavor and texture of pain au lait - the best I’ve come up with is to say that its like a cross between brioche and well made biscuit – light and tender, not too rich. The formulation mirrors brioche in ingredients, but in different proportions. And its lightness is due in part to further lamination – rolling and folding the dough. The result is a consistency that allows for rare precision in portioning and make-up to create a striking, uniform size and shape.

Though I’ve seen larger loaves, I think pain au lait is best expressed in small format. Well-rested after a third single-turn, the chilled dough is rolled and portioned with the aid of a ruler. After a gentle proof, the top is brushed with egg wash and sprinkled with coarse salt to produce a striking individual piece.

 

Pain au Lait

This return to bread has inspired a new discipline of near daily regimen of baking sessions – only a week in, I’m having a blast!

Pain Seigle

 

Below, my formula for pain au lait:

Pain au Lait – Opusculum

 

Just a few of many, many favorite bread resources include:

Bread: A Baker’s Book of Techniques and Recipes, by Jeffrey Hamelman

Special and Decorative Breads (The Professional French Pastry Series)

Tartine Bread, by Chad Robertson

For general inspiration:

Stephen Jones and the Washington State University Bread Lab

Dan Barber, at the MAD Symposium, 2012

 

Peter Reinhart’s TED talk, 2008

And in case you haven’t heard, the Modernist Cuisine lab is currently at work on their own exploration of bread - with Francisco Migoya and Peter Reinhart on the team, I’m beyond excited to see how that project develops!

 

Ice Cream

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My history with ice cream probably mirrors that of most other cooks: from not really knowing what I was doing to becoming fully obsessed with its inner workings. As one begins to grasp a better understanding of ice cream, it becomes at once easier and oddly far more difficult. The more you know, the more you realize you don’t know.

Let me be honest – this is not going to be the epic treatise on ice cream or the last word on a subject that I’m wholly unqualified to author. I will instead propose a handful of obvious (or not so obvious) concepts that might simply serve as a launching point deeper into the science of the subject.


FIVE THINGS TO CONSIDER ABOUT ICE CREAM

1. While there may be no one ‘ideal’ ice cream formula, one can assemble that formula much like an algebraic equation based on the desired end result. The key to success is knowing which components are proportionally fairly static and which are variable. And then it’s about knowing how your ingredients supply these basic components.

One can very generally place ice cream formulas and their constituent components within the following ranges:

Milk Fat 10% – 16%

Egg Yolk Solids 0% – 2%

Nonfat Milk Solids 9% – 12%

Sweeteners 12% – 16%

Stabilizers and Emulsifiers 0% – 1.0%

Water 55% – 64%

There are, of course, exceptions. Gelato-style products often have a fat content in the 7-8% range; soft serve products may contain 5% fat or less. My own go-to formulas tend to fall within a range of 7-9%, though technically I could never commercially call it ‘ice cream’, which is defined by U.S. law as containing a minimum 10% milk fat.

Crucial to understanding how to build an ice cream formula is knowing the composition of your ingredients. Of course, I think this basic information is important no matter the preparation at hand. With knowledge of an ingredient’s composition, structure, and function comes true power to the cook. Rather than thinking of milk as simply ‘milk’, one must look at it as a system of water, fat, protein, and sugar; it’s structure is at once an emulsion, a suspension, and a solution.

Below, a useful chart for comparing the composition of milk and its commonly used derivatives:

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And if we employ egg yolks in the formula, it is helpful to know the following:

One “Large” Egg Yolk = 20g

Comprised of, approximately:

50% water

10% proteins

30% fat

10% lecithin

 

Milk fat and sweeteners will be covered further below, but these charts alone can immediately set us on the path of formulating new ice creams, or reverse-engineering existing recipes to see where its components may fall along the formulation spectrum.

2. Water containing dissolved solids such as salt and sweeteners are affected by something we refer to as colligative properties. These solutes will raise the boiling point of water on the high end of the temperature range, and at the low end, they lower the freezing point of water. It is this very property of freeze point depression that makes ice cream possible at all – that at serving temperatures below water’s freezing point it is soft enough to scoop and chew.

Different solutes – for the sake of our discussion, sweeteners – will lower the freezing point of water to different degrees. The measurement that we use to correlate freeze point depression is a sweetener’s molecular weight – the lower the molecular weight, the greater the effect of freeze point depression. Sucrose, for example has a molecular weight of about ‘342’, with fructose coming in at about ‘180’ and an average glucose at ‘428’. With this we can say that a solution of fructose will lower the freezing point water nearly twice that of sucrose, while a glucose solution will raise the freezing point. What does this mean for an ice cream maker? Simply put, we can use multiple sweeteners to modify the freezing point – the relative firmness or softness – of an ice cream.

Different sweeteners also have a different ‘sweetening power’, which allow us the ability to fine tune the perceptible sweetness in addition to adjusting freeze point depression, all while maintaining a fairly constant percentage of total sweeteners. Sucrose is given a sweetening power of ‘100’, with fructose at about ‘125’, and glucose somewhere in the range of ‘50’ (glucose can offer a confusing range of properties based on how it is processed – that may well be a different discussion at a different time). Thus, for the sake of comparison, replacing some of the sucrose in a formula with fructose will simultaneously give us more sweetness while also lowering its freezing point. Far more useful to us is the fact that added glucose will offer less sweetness while also raising the freezing point, giving us firmer textures at higher temperatures. It is also helpful to know that lactose, with a relatively low perceptible sweetness will still lower the freezing point at the same rate as sucrose.

The chart below offers a rough comparison of these properties among a range of sweeteners. RFDP refers to relative freeze point depression in relation to sucrose, which is given the arbitrary factor of ‘1’. SP refers to sweetening power. The column under Max. % refers to a generally accepted use in ice cream formulas. These figures were culled from various sources over a long period of time – one may see slight differences between sources – especially with regard to sweetening power – but I think this gives us a good rough guideline to work with.

Sweetener Properties

It may also be worth noting the molecular weight and RFDP of sodium chloride – salt – at ‘54’ it will lower the freezing point of water over six times that of sucrose (which why we put salt on icy roads and not sugar!). And ethanol – a component in alcohol – will lower the freezing point by a factor of seven times that of sucrose, with its molecular weight of ‘46’. Formulating ice creams with alcohol can often be frustrating; two general rules of thumb to consider are the need for a reduction in dissolved solids (down to 23-25%) and the addition of a maximum of about 7% pure alcohol. Formulations must also be adjusted when adding ingredients like chocolate and fruit – which might bring sweeteners, water, or fats of their own. I know, the math just got a lot harder.

3. In addition to supplying creamy mouth feel, the milk fat content of ice cream will determine its basic physical structure. The best way to understand the structure of ice cream is to step back and consider first the structure of whipped cream. As we whip heavy cream, we can begin to visualize individual fat particles swirling around the continuous phase of water, slamming into each other almost as if in a mosh pit (my favorite way to describe it). We know that cream whips up best when it’s cold; this is because at low temperatures most of the milk fat is crystallized – solid – which allows the individual particles to stick to one another while maintaining to some extent their own identity (as opposed to simply fusing into larger and larger fat particles). With help from some of the milk proteins, these partially coalesced fat particles begin to form a kind of ‘scaffolding’ – a solid structure – that also traps the air bubbles that are incorporated into the cream as it is being whipped. Ok, that’s whipped cream.

Understanding the structure of whipped cream helps us understand the structure of ice cream because, on a microscopic level, they are really quite similar – the only differences being that there is usually a lot more ‘stuff’ dissolved in the water phase of ice cream (sweeteners) and that some of the water exists as ice. Below, a set of graphics that helps illustrate this idea, courtesy of my friend Cesar Vega, and one of his mentors in ice cream, Douglas Goff (2007):

Whipped Cream  Ice Cream

Also important in the formation of the structure of our finished ice cream is the relative size and dispersion of the milk fat particles. We almost always heat our ice cream bases in order to dissolve sweeteners, cook proteins, and pasteurize the final mix. This heat will liquefy the previously crystalline milk fat; upon cooling the milk fat will have a tendency to form large fat particles. In recent years I have become fanatical about homogenizing the mix after cooking, to aid in breaking up those fat particles, which ultimately give way to better structure. A thorough buzzing with an immersion blender, while not the perfect tool, will certainly yield better results than skipping the step outright. An aging period is also important, among other reasons, as it allows those milk fat particles to properly crystallize.

In short, understanding how the milk fat in our ice cream behaves on this underlying structural level can lead us to make certain determinations on how we process ice cream, its overrun, and its melting qualities. More food for thought: spinning ice cream in a batch freezer allows this partial coalescence of fat to occur (the ‘scaffolding’), while processing the same ice cream in a PacoJet merely ‘slices’ the already frozen base into finer particles. An interesting experiment to try is comparing the melt down of identical ice cream formulas processed in each machine – which do you think might melt faster? Why?

More food for thought: ‘re-spinning’ ice cream should be discouraged solely for hygienic reasons, but we can also begin to imagine how it can be problematic from a structural point of view…

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4. Ice cream is made up of a lot of ice. Obviously, right? Ice defines its nature, yet improper formulation or handling can result in the ice emerging as negative attributes – too much of it, or in too large a crystal size. Two important concepts to remember:

The amount of solutes in the unfrozen water phase determines volume of ice crystals that form.

and

The rate and speed of freezing the base mix determines crystal size – the lower the temperatures, the faster the base freezes to produce the smallest possible ice crystal. These ice crystals will always be at their greatest number and smallest size the moment they are extracted from the machine – they can never get smaller.

In other words, where the type of sweeteners we choose will determine the freeze point depression and overall sweetness of the ice cream, the sum total of those sweeteners will determine how much of the water will turn to ice. Easy. Also interesting to consider is the idea of freeze concentration: as a solution freezes, only pure water crystallizes in to ice, which means the concentration of solutes in the remaining unfrozen water increases, which also means that the freezing point of that water continues to drop as more water turns into ice. Thus, even at a temperature of about 3˚F/-16° C – below the typical serving temperature of ice cream – only about 72% of the total water in a base mix is frozen as ice. The rest remains unfrozen as a very concentrated sugar solution.

And then we turn to keeping those ice crystals as small as possible. It’s all about speed and temperature. A high end batch freezer that can process ice cream in a few minutes will make better ice cream than lower end methods that may take much longer to freeze. It’s a classic example of getting what you pay for. Rather than using visual clues to determine when the ice cream is ‘done’, I typically spin my ice creams to a temperature of about -5˚C/23˚F, (at this point only half the water in the mix has frozen) and transfer to a blast freezer to fully ‘harden’ the ice cream. From here it makes sense that as the ice cream is exposed to increasingly higher temperatures some of that frozen water will melt, forming increasingly larger crystals if and when the temperature drops again. This is usually referred to as thermal shock. Related but slightly different, is accretion, the fusing of large ice crystals stored at higher temperatures over time. For example, the acceptable ‘shelf-life’ – texturally speaking – of ice cream stored at -4˚F/-20˚C may be up to two weeks, but increase the storage temperature to 5˚F/-15˚C and that shelf-life dramatically drops to one or two days.

Spin your ice cream as quickly as possible and store it as cold as possible.

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5. Stabilizers and emulsifiers do different things. Stabilizers collectively refer to a category of additives  – most often polysaccharide hydrocolloids – that act upon the water phase alone. Technically speaking, stabilizers do not interact with or directly influence emulsions of fat and water.

HYDROCOLLOID = HYDRO + COLLOID = WATER + STRUCTURE

Stabilizers are responsible for adding viscosity to the unfrozen portion of the water contributing to overall mouth feel, and enhancing  the ability of the base mix to hold air during the freezing process. Binding water stabilizes it, so that it cannot migrate within the frozen product. Without the stabilizers, the ice cream would become coarse and icy very quickly due to the migration of this free water and the growth of existing ice crystals. Stabilizers improve (slow) melt down and help to prevent thermal shock.

 Emulsifiers are a group of compounds in ice cream which aid in developing the appropriate fat structure necessary for the smooth eating and good meltdown characteristics desired in ice cream. Milk proteins present act as initial emulsifiers and give the fat its needed stability. Supplemental emulsifiers are added to ice cream to actually reduce the stability of this fat emulsion by replacing proteins on the fat surface, leading to a thinner membrane more prone to coalescence during whipping.

Emulsifiers are characterized by having a molecular structure which allows part of the molecule to be readily ‘anchored’ in water, and another part of the molecule to be more readily ‘attached’ to fats: hydrophilic and lipophilic. When we use egg yolks in an ice cream base, the 10% lecithin that they contain performs this function to some degree. Common emulsifier additives used in commercial stabilizer blends include mono- and di-glycerides or polysorbate 80.

When the mix is subjected to the whipping action of the batch freezer, the fat emulsion begins to partially break down and the fat particles begin to destabilize. As previously mentioned, the air bubbles which are being beaten into the mix are stabilized by this partially coalesced ‘scaffolding’ of fat. If emulsifiers were not added, the fat globules would have a ‘chaotic’ structure, resistant to coalescing, resulting in a weaker structure and less desirable texture. Interestingly, as the milk fat content of the base increases, the need for a stabilizer blend decreases.

Attached here is my standard formula that, after years of tweaking, I often use to build from as I plug in other ingredients. But starting from zero on your own is well worth the exercise.

Vanilla Ice Cream – Opusculum

There are numerous resources from which I’ve gathered this information over time, and from which the subject can be further explored. A few of my favorites include:

Ice Cream, by H Douglas Goff , Richard W Hartel

Frozen Desserts, Francisco Migoya

 

i Segreti del Gelato, Angelo Corvitto

http://www.angelocorvitto.com/

University of Guelph (Ontario), Dairy Education Series 

https://www.uoguelph.ca/foodscience/ice-cream

Also of interest, from my ice cream guru, Cesar Vega:

The Kitchen as Laboratory: Reflections on the Science of Food and Cooking, by César Vega, Job Ubbink and Erik van der Linden

 

 

 

To learn more detail on the underlying science of ice cream, I’ll be teaching a short form class on the subject on July 30th 2014 at the Institute of Culinary Education in NYC!

 

Minor Works

“Success is the sum of a lot of small things correctly done.”

Fernand Point, Ma Gastronomie

The word opusculum typically refers to small, minor works of literature or music. Our work in the kitchen – even at its most grand and complex – is really just the sum total of smaller singular efforts brought together to make, one hopes, a greater whole. An attempt to put one’s arms around the broad scope of ingredients and methods at our disposal – at once and with authority – is daunting at best. In order to bring focus to our methods and to sift through the static of ideas and inspiration, I prefer to magnify the individual actions and elements that make up our movements. And for whatever reason, as in the past with other projects, I feel compelled to share the work as a means of giving something back in return for all that I’ve seen and tasted over the years.

To follow is a personal exploration of the inventory – a lexicon, if you will – of the pastry kitchen and whatever spheres that may intersect it, the small moments of discovery and rediscovery and continuous efforts of honing one’s craft.

Lamination - pain au lait, May 2014