Pâte de fruit is boring.
Maybe I should qualify that by saying instead that there is a reason why it ends up on most restaurant petit four programs. It’s fairly easy to prepare in bulk, it has a long shelf life when stored properly, and it’s relatively inexpensive in terms of ingredients and labor. There is a reason why an assortment of petits fours usually represents a round-up of the usual suspects (along with marshmallows, caramels, macarons, etc.). Rarely can one devote unlimited resources (time, space, money) to upgrade these tiny bites to the next level of complexity and deliciousness. That’s why – at least for pastry cooks – they tend to get boring, even with the occasional variation.
That’s a harsh stance, but I do feel room for innovation remains. As with most preparations, possibilities expand exponentially when afforded greater insight into their inner working. Below, a few fast facts regarding pectin gels such as pâte de fruit…
The broad range of available pectin and their properties present an understandable degree of confusion, compounded by the fact that in many cases our access to that spectrum is actually limited to vaguely defined products provided by a handful of purveyors.
Pectin exists in nature in most plant material as a high molecular weight polysaccharide ‘glue’ that holds its cell walls together. Some plants and their fruit contain more pectin than others, and its solubility is affected by factors such as ripeness of the fruit. Historically commercial pectin has been extracted from citrus peels and apples through a process of hydrolysis – using heat, water, and acid. Factors ranging from the type of raw material to the processing method will affect a pectin’s properties, primarily its DE, or ‘degree of esterification’, which determines its methoxyl content. While I don’t think pastry chefs necessarily need to fully understand the precise chemistry involved (I certainly don’t), what is important to understand are the key differences in properties of either high- or low-methoxyl pectin. Further, low-methoxyl pectin can be classified by DA, or ‘degree of amidation’, which also affects its performance. When discussing pâte de fruit, we will concern ourselves primarily with high-methoxyl pectin.
Low-methoxyl pectin does open up a world of possibility; it gels in the presence of calcium and within a broad range of solids content and pH. Generally, LM pectin is also thermo-reversible where HM pectin is not; one cannot ‘melt down’ an HM pectin gel like pâte de fruit and recast it. A common version of LM pectin available to pastry chefs is known as NH pectin, which is often used in preparations like neutral glaze.
High-methoxyl, or HM, pectins are those with a DM exceeding 50%, and their primary function is gelation. Pectins gel under conditions of reduced water activity – or a high degree of soluble solids such as sugars – and low pH. Generally an HM pectin will gel when the soluble solid content is between 55%-85% and the pH is in the range of 2.0 to 3.8. Generally the higher DM of a pectin, the easier the gel forms; a pectin of very high DM, for example 72%, will gel at a very high temperature and thus sets very quickly and is referred to as ‘rapid set’ pectin. ‘Slow set’ pectin may have a DM of 60% and gel at a lower temperature. Though the attributes of a gel are due to many factors including the specific recipe and its ingredients, often pectin is chosen based on processing needs. With pâte de fruit, I may wish to seek out the flexibility of slow set pectin if I am looking to deposit individual pieces, as opposed to casting a large slab to be cut later. Rapid or slow set can also play a role in aiding the suspension of solid pieces (rapid) or reduction of air bubbles (slow). If using a vacuum cooker (see below), the much lower cooking temperature would require a slow set pectin.
Final strength tends to be standardized by the industry (typically referred to as SAG 150±5), thus setting time and temperature is a common way of distinguishing one pectin from another; below is a general guideline of such ranges, though an increase in amount of solids or a lower pH can also affect the setting conditions :
The pectin we may have available to us does not usually offer its DE, let alone whether or not it is of a decidedly rapid, medium, or slow set variety. When possible I use a ‘yellow’ or ‘ruban jaune’ pectin for pâte de fruit, designed to offer a fairly slow set with a solids content greater than 75% and within a range of 3.2-3.5 pH. Otherwise, what often is labeled ‘apple pectin’ does the job well enough. At the end of the day, choosing one pectin over another comes down to what is available, and perhaps a bit of trial and error to find what works best on a consistent basis.
Dosage is most often determined by the amount of naturally occurring pectin present in the base fruit puree. Added pectin will generally be about 1% (or slightly higher) of the initial weight of ingredients – more for fruits that contain little usable pectin of their own. This is why it is common to fortify pectin-weak fruits with additional purees such as apricot, apple, or pear to offset this deficiency; indeed I come across many pâte de fruit recipes that call for apple juice as a consistent practice, no matter the base fruit being used.
Pectin is prone to clumping upon contact with liquid, so it’s vital to dry blend the pectin with some of the sugar used – typically about 5 times the weight of the pectin – to thoroughly disperse. I also like to heat the base puree to at least 40˚C/104˚F before adding the pectin, and most importantly, maintaining a temperature above 60˚C/140˚F during the addition the remaining sugars by adding them gradually – the most common fail with pâte de fruit occurs when all of the sugars are added at once, dropping the temperature and resulting in a weak final set.
Sucrose is overwhelmingly the bulk sweetener of choice, with the addition of some glucose to both inhibit crystallization and slightly reduce overall sweetness. I occasionally see invert sugar used in small amounts as well. Added sugars will also fluctuate slightly based upon the amount of sugar supplied by the fruit itself. Part of what makes pâte de fruit boring is that because of the need for high solids content (sugar), most of the potential flavor is obscured by sweetness. To this end, I’ve been playing around with sugar alcohols and even low DE maltodextrin (here, meaning ‘dextrose equivalence’) to reduce sweetness. With the end goal of perhaps approaching what one might even call a ‘savory’ pâte de fruit. There may be limits to how much sucrose can be replaced with other sweeteners, but I hope to discover just what those limits are. Below a general reference chart for sweetener composition and properties:
The addition of acid is also critical in dropping the pH, allowing for the pectin to reach its final setting conditions. We most often see citric or tartaric acid used in pâte de fruit, but malic acid also works just fine. Something as simple as lemon juice will work, but is perhaps difficult to control. Given the circumstances I do not personally feel that one can taste any difference when one acid is used in place of another. I usually do not find it a problem to add the acid in dry form directly to the cooked mass, but it is far safer to dissolve the acid in an equal weight of water to help disperse it into the molten mix, especially when working with a rapid set pectin.
As previously mentioned, maintaining high temperatures during the addition of the sugars is crucial, but so is cooking to the correct temperature. Final cooking temperature is a fairly standard 106-107˚C/222-224˚F. This temperature also correlates to the final solids content of a water/sugar mixture – boiling point elevation as a function of dissolved solids is what we call a colligative property (as is the depression of the freezing point). Part of the reason it seems that confectioners use temperature to calculate solids content is in part out of ease, but also because it is an imperfect science: it is difficult to precisely measure solids/water content under the extreme conditions of heat (see the Hartel article below).
Values vary widely by source, but the chart below begins to offer a rough idea on the correlation between temperature and the solution of sucrose in water (alongside the old school visual test method). Of course in the case of pâte de fruit, the addition of other sugars such as glucose would cause these figures to change ever so slightly:
The above figures of course hold up under normal atmospheric pressure, but I’ve been recently turned on to the possibilities of vacuum cooking, which allows for moisture reduction at far lower temperatures. For example, if cooking a sugar syrup to 150˚C/300˚F to achieve a solids content in the neighborhood of 2-3%, pulling a vacuum to 25inHg (inches of mercury) would give the same results cooked to the far lower temperature closer to 93˚C/200˚F. Not only is this far lower than the caramelization point, but it is also below the threshold where Maillard reactions begin to take place – allowing for ‘white’ caramels. So what would this mean if applied to pâte de fruit? I’m not sure yet, but the final cooking temperature could be reduced to 81˚C/178˚F (from 106˚C/223˚F using an open system). Perhaps when cooked under a vacuum it would retain better color and flavor and result in less inversion of the sucrose and less degradation of the pectin. This small batch vacuum cooker below is currently on my wish list should be arriving to a shiny new ICE confectionery lab in a few months:
Back to the cooking process before moving on, and a point that I cannot stress enough: outside of inaccurate scaling or undercooking, from my observation the most common cause of improperly set pâte de fruit is the sudden drop in temperature that occurs when the sugars are added too quickly. Slow and steady wins the race. And of course once the acid is added setting begins at a rapid pace, so that’s when one must act quickly and decisively. Recently wrapping my head around the idea of how to use the pasteurizer portion of our Bravo Trittico machine to cook pâte de fruit, it became more a question of how to extract it. The solution was a simple one: cook the mixture to the necessary temperature and extract from the machine (while still quite fluid) into a bowl before adding the acid.
The typical finishing of pâte de fruit is sort of like adding insult to injury – sugar on top of sugar. Whenever practical, I like to blend 1-2% of an acid into the sucrose used for dusting, or a dry spice, or any dried and powdered flavoring. Such a simple detail of added flavor can do a lot to elevate the ho-hum status of pâte de fruit to above-average.
So, with better insight into the mechanics of how pâte de fruit really works, what do we do with it? Well, for me, even the most boring tasks become exciting again once I better grasp the science, so there’s that. Though I had already begun playing around with savory flavors and alternative sugars, I was inspired to go back to square one and make pâte de fruit with nothing but water; a ‘pure’ starting point from which to remove conventional associations and move in new directions. If through baby steps I arrive today at a less sweet carrot, red pepper, or balsamic vinegar pâte de fruit, perhaps tomorrow might bring jellies flavored with mushroom, artichoke, white bean, etc. I realize that there are several methods beyond pectin that we could use to gel a savory liquid. But none would give me just that texture a conventional pâte de fruit provides. In the end maybe these flavors and that texture just aren’t compatible (or palatable).
If the journey is in fact more important than the destination, I’m more than happy to take this ride to see what happens along the way.
Below, the formula for a recent favorite of mine, a duo of grapefruit and Campari:
An interesting (and free) paper by confections experts Richard Hartel, Roja Ergun, and Sarah Vogel that in part addresses the difficulty in measuring solids content of high temperature syrups:
A great way to begin understanding pâte de fruit formulas is to reference the parametric charts published by companies like Boiron; their latest edition below:
Chocolates and Confections: Formula, Theory, and Technique for the Artisan Confectioner, 2012
by Peter P. Greweling
Science of Sugar Confectionery, 2000 by William P. Edwards
Alternative Sweeteners., 2001 by Lyn O’Brien-Nabors.2001
And did you know that Kitchen Arts and Letters in NYC now sells books online? Awesome!