The Chocolate-Tempering Process is Simple to Initiate, but Difficult to Control
Most times when we hear the term chocolate tempering we think about the initial creation of Form V nuclei that causes the chocolate to solidify with traditional cocoa-butter-based chocolate characteristics: gloss, snap, and smooth mouth feel. While it is important to nucleate chocolate with Form V crystals, it is equally important to control the multiplication, growth, and agglomeration of those crystals in order maintain the chocolate at an acceptable thickness for the longest timeframe possible.
To achieve this goal, we need to monitor the thickening of a tempered chocolate over time. Picture 1 demonstrates a simple spatula drag test that provides a low-cost, subjective way to measure changes in a chocolate thickness. Picture 2 shows the spatula used to perform the test. When used properly, this simple test provides the chocolatier with information that equips him to make decisions related to how much heat can be added without melting too many Form V crystals. We are demonstrating the monitoring techniques discussed in this article by using a rotary bowl tempering unit. However, you can use the principles and techniques with any batch tempering system to which the temperature of the chocolate can be controlled and to which there is safe access to the chocolate pool.
You can break down every tempering process, whether manual or mechanical, into several stages. The first stage is the complete melt-out of some or all of the chocolate. The purpose of this stage is to achieve maximum fluidity of the chocolate mass through the liquefaction of the fat system. The second stage is the cooling of the chocolate to the proper seed addition or seed creation temperature range. The third stage is nucleation. You can accomplish this by either seed creation or seed addition. By seed, we mean Form V crystals that are either added by the incomplete melting of a previously solidified tempered chocolate or created by shearing a chocolate on a surface at a temperature at which Form V crystals actively form. This mass, seed, is mixed back into the fully melted chocolate that is cooled to a temperature at which the crystals become nuclei that transform lower forms of cocoa butter into Form V upon solidification of the chocolate. The fourth stage is the growth and multiplication of nuclei, Form V seed, into crystals.
Multiplication and growth of nuclei in this stage start slowly but increase rapidly as more and more nuclei are available to interact with one another. In the fifth and final stage, crystal formation slows down, but crystals increase in size through absorption of other crystals and agglomeration of multiple crystals. In this stage, a chocolate will quickly become too thick to use unless you control crystallization by increasing the temperature of the chocolate or by diluting of the chocolate using non-tempered chocolate. While learning to control each stage is important, the focus of this article will be on monitoring and controlling stages three and four, as this leads to the ability to increase usage time and the amount of product that can be made from a single tempering session.
With the understanding that a tempered chocolate thickens over time due to both an increase in crystal number and size, we can now discuss how to monitor and control this process. Figures 3 to 5 illustrate this change in thickness. For the purpose of this article, we tempered a dark chocolate with a 31% fat content. Picture 3 shows the chocolate 30 minutes after seed was added to the chocolate held at 88.7˚F. Notice how the chocolate quickly rolls back on top of itself. Figure 4 shows the same chocolate after three hours at 88.7˚F. Notice the deepness of the V after the blade cuts through it. This indicates that there are more crystals then at the 30-minute time point. Picture 5 shows the same chocolate as in Picture 4 after its temperature was increased 1˚F to 89.7˚F. Notice how the V formed by the blade is much less defined then in Picture 4, but more defined then in Picture 3, indicating there are still plenty of crystals. With experience, the chocolatier can monitor the presence of the V formed by the blade, allowing him to decide when adjustment to a process is necessary. Pictures 3 through 5 were taken in a rotary bowl batch tempering unit with the bowl turning.
Picture 6 depicts the same unit during a stage when the bowl was not turning. The blade was simply pulled through the chocolate from the edge of the bowl to the baffle. As Form V crystals form, they do not flow back into one another when moved, but rather stack on top of each other. This metric measures the structure of Form V crystals in relation to other forms and can be used as an indicator of a well-tempered chocolate.
It is important to maintain a consistent chocolate thickness over time, since that allows you to control a quality parameter such as truffle center-to-chocolate ratio. That also affects the ease of air-bubble removal, corner fill of molded items, and ability to obtain a uniform thickness of the shell form in hollow molds.
There are two primary methods available to control the crystallization rate of a tempered chocolate. First, you can increase the temperature of the chocolate to minimize or even stop nucleation, but retain the desired amount of Form V crystals. This requires increasing the chocolate’s temperature over time as the chocolate thickens. Since every chocolate will have its own rheology and crystallization properties, it is best to Increase the chocolate’s temperature from the seed addition temperature in small increments as the chocolate thickens and is known to have sufficient seed to solidify properly (0.1 to .5˚F). Once that happens, you can increase the temperature in larger increments of .5 to 1˚F as long as you never go over 92˚F as the hold temperature. Again, this is very dependent on the formulation, because of how the amount of milk fat in a formula will affect the rate of crystal growth.
The second option is to dilute the mass with non-tempered chocolate to reduce thickness by not only decreasing the quantity of Form V crystal through dilution, but also melting out some of the present seed by controlling the temperature of the chocolate being added. When used properly, this method allows you to continue a tempering session almost indefinitely. When you do this, keep in mind two parameters that you need to control: the temperature and the quantity of the chocolate you add back to the chocolate. In this process, the diluting chocolate must be totally melted and then conditioned to a temperature between 90 F and 94 F. The higher the temperature of the chocolate, the lower the amount of unseeded chocolate that you can add back to the tempered chocolate. In general, between the temperature of 86˚F and 90˚F you can add back up to 2/3 of the total amount of tempered chocolate when the chocolate in the bowl is about 1/3 full, or 160% of the chocolate in the system. You can repeat this process as long as the remaining chocolate is in a well-tempered state. After each backfill, you should stir the chocolate well and let it sit for at least three minutes to ensure a homogenous mixture. If you don’t perform this mixing, you may get streaks in the chocolate as it solidifies if lower forms of crystals solidify without being in contact with a sufficient number Form V crystals.
While this technique will take a little time to learn, the user can expect a triple payoff of longer production times, less rework and more controlled chocolate usage. For more information on this subject or if you would like assistance in another area, please visit sweetanchors.podia.com for other training opportunities.
(This article appeared in the Winter 2024 issue of Pastry Arts Magazine)
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