by Dennis Teets
What do we mean by tempering chocolate? We are talking about the creation of a sufficient number of beta crystals in a liquid chocolate so the chocolate will solidify with the desired physical traits of gloss, snap, mouth melt and proper handling for packaging.
While looked upon by many as art, it is actually the controlled crystallization of the cocoa butter in the chocolate’s fat system. This root process is the same, whether you work with a simple hand tempering process or a complex manufacturing process. This process consists of five physical steps: crystal melt out and flow maximization, cool down to nucleation development temperature, nuclei development, dispersion of nuclei and optimization of crystal growth to achieve desired flow properties. In this article we will explore how to use a microwave as a heat source for softening previously tempered chocolate to add beta crystal nuclei to the cooled supply chocolate.
Before we explore this topic it’s important to develop a common language for the different crystalline states of the chocolate found at different steps of the tempering process:
- Base Chocolate: the chocolate used in creation of the chocolate product.
- Supply Chocolate: the base chocolate heated to achieve maximum flow characteristics and remove all crystals.
- Seed Chocolate: a solidified, well-tempered chocolate whose temperature has been kept below 90°F to retain beta crystals.
- Nucleated Chocolate: the supply chocolate at a temperature between 85°F and 90°F to which seed chocolate has been added.
- Seed Crystal Burnout: the loss of beta crystals from a seed chocolate to the point that it will not nucleate the supply chocolate. Burnout begins when a chocolate reaches a temperature of 89°F to 90°F.
The Science behind Beta Crystal Nucleation
There are two basic ways to develop beta crystal nuclei in a chocolate during the tempering process: seed creation and seed addition. Seed creation is the forming of beta crystals by shearing it on a cold surface to form nuclei and tabling. Use this method when no seed chocolate is available. Seed addition nucleation is the dispersion of formerly formed beta crystals into a supply chocolate cooled to between 84°F and 89F. Most often, you can accomplish this by using a well-tempered chocolate, but you can also accomplish it by forming beta crystal in cocoa butter. This article will discuss how to accomplish seed nucleation using a microwave as a heat source to soften seed chocolate.
Microwave Heating of Chocolate
Traditional heating methods such as a double boiler, induction stove, or a hot plate all have an external heat source from which heat is transferred into the chocolate through conduction.
The microwave employs dipole heating. This heating occurs as polar molecules in the chocolate are excited by magnetic radiation, causing the molecules to vibrate. This process creates friction, which then creates heat. However, this vibration quickens as a chocolate liquifies, thereby causing more friction. You’ll need to shorten the time sequences as the chocolate approaches its desired softened state in order to prevent it from overheating. This change follows a pattern based on the melt point of the cocoa butter crystals.
You can apply this profile to any type of chocolate since it is based on the target temperature related to the crystal state and not the formula. This is important because the softening of a chocolate for nucleation requires a precise target temperature range that is only five degrees wide and must not go over 90°F, the temperature at which beta crystals actively begin to melt.
Now that we understand how a chocolate melts, let’s discuss the three factors that come into play when using a microwave to heat chocolate: total wattage (total power applied during a heat sequence), percent power and sequence time.
Total Wattage
Wattage is the total power applied during a heat sequence. The unit used for this article was a 1200-watt unit. In other words, the microwave generated 1200 watts of power while it operated. In general, the wattages for home microwaves range from 600 to 1700 watts. Lower wattage microwaves may require higher percent power, longer sequence times, or a combination of both. A higher wattage microwave may require a lower percentage of power, shorter sequences, or a combination of both. Future work needs to be done to predict more accurately the interaction among wattages, percent power, and sequence time.
Percent Power
Percent power represents the amount of time in a heat sequence that the magnetron is actually heating at the microwaves designated wattage. So, 30% power means the microwave is heating 30% of the time during the sequence at 1200 watts. In order to keep variables to a minimum 30%, we used power on all heat sequence presented in this article. It was high enough in power to melt efficiently, yet low enough to prevent instant overheating and thus burning of ingredients.
Heat Sequence Length
We made heat sequence adjustments based on the temperature difference from a target temperature that represented the crystal content of the chocolate. For nucleation, the goal is to reach a temperature at which the seed chocolate is dispersible but still maintains sufficient beta crystal to seed the supply chocolate. This temperature varies with formula, but was standardized in this case at 90°F to ensure the least number of issues with crystal burnout.
Defining the Seed Softening Process:
A solidified tempered chocolate softened first by the melting of lower melt-point fats (milk fat) and lower forms of cocoa butter crystals (Forms 1 to 4). This resulted in a softened semisolid state because the sugar, cocoa powder and cocoa butter beta crystals were free to move in the chocolate after these lower melt fats were heated. The goal temperature range can be categorized by three observable states. First, (see Figure 1), as a solid, penetrable by the temperature probe or other sharp item. This state occurs at temperatures ranging from 75°F to 82°F. You can generally reach this state by the end of the first sequence. Reaching 82°F is a sign to shorten sequence length to 30 seconds. Second, (see Figure 2), the chocolate becomes sliceable to compressible. This occurs between 83°F and 85°F and is a sign to shorten heat sequence length to 15 seconds. Finally, (see Figure 3), the chocolate can be compressed into a smearable mass, this generally occurs between 85°F and 88° F.
The actual temperatures will vary with the exact formulation and even the length of storage, which affects the amount of beta crystals in the product. If the chocolate is not in a dispersible state, future sequences should be in seven-second increments until you obtain a dispersible material. The goal is not to go over 90°F.
For the process of softening seed chocolate, this means that you need to shorten the length of the sequence as the chocolate moves towards its target temperature. These time changes correspond to the change of the crystalline structure of the chocolate’s fat system.
- Ensure supply chocolate is close to nucleation temperature range of 86°F to 90°F
- Determine the amount of seed chocolate required to temper your batch.
- Place seed chocolate on parchment paper or another flat microwaveable surface.
- Microwave at 30% power for 60 seconds.
- Mix the chocolate and check the temperature and condition of the chocolate – Normally the temperature of the chocolate after the first sequence will be around 80°F to 83°F. (See Table 1 for time-change guidelines.) Watch for cabinet warming. While testing this method, I discovered that the oven temperature increased after each sequence. This happened when I softened two chocolates back-to-back and the total amount of time exceeded 3.5 minutes. The result was a chamber temperature of 95°F and a chocolate temperature of 92.5°F. This chocolate was too warm to be used as seed.
- Continue with sequences until chocolate becomes smearable or temperature reaches 89°F.
- If the chocolate temperature exceeds 90°F, you should restart the process with new seed chocolate.
- Once you achieve desirable flow properties, immediately add the softened seed chocolate to the cooled supply chocolate and mix thoroughly. This chocolate is now tempered and can be used for the desired chocolate project.
Using Seed Softening Process
In summary, once we understand how a chocolate melts in a microwave, the microwave can provide a controllable, quick, and low-cost method for creating dispersible beta crystals for seed-addition methods of tempering. For more in-depth information on how to temper chocolate using a microwave as a heat source, go to sweetanchors.podia.com. Until next time, may all your seed crystals be beta.
Dennis Teets spent 30 years working in the confectionery industry as a product developer, researcher, scientist, trainer, innovator and consultant. He now runs a confectionery coaching website: https://sweetanchors.podia.com
(This article appeared in the Fall 2025 issue of Pastry Arts Magazine)
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