Beat Migration Bloom on Chocolate Products by Optimizing ... - AAK

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<strong>Beat</strong> <strong>Migration</strong> <strong>Bloom</strong> by Optimizing Your Process Heat treatment at 28°C for one week purifies the polymorphism and at the same time inhibits visual bloom development for 12 months despite the oil migration. Dsc performed on the chocolate at a distance of 0.5mm from the nuts shows a 0.6°C higher melting peak value in the chocolate which is heat treated at 28°C compared with the 20°C “heat-treated” chocolate, and exactly the same difference is found 10mm from a nut surface for both. It seems that heat treatment at 28°C for one week purifies the polymorphism and at the same time inhibits visual bloom development for 12 months despite the oil migration. This suggests that either the tempering or the cooling or both favored Form IV crystallization that was expressed as bloom in the non-heat-treated samples. It shows how important it is to control crystal development and ensure crystal stability to re- tard bloom development. A theory could be that if this transformation happens fully above the solidification point of Form IV for this chocolate’s particular TAG composition, no visual bloom is developed and all Form IV crystals are moved to Form V without bloom development. However, if this transformation happens at a lower temperature, below the Form IV solidification temperature, larger bloom crystals will appear. One week at 28°C has speeded up the migration to an equilibrium state and no essential Form IV-to-V transformations happen after the one week and therefore no bloom develops. Of course, bloom will reappear when the Form V-to-VI transformation starts, but that takes much longer and is therefore not the big- gest problem for producers of filled products. The above theory explains the results from Results from Heat-treated Filled Praline Bars 6 May 2010 • Reprint from The Manufacturing Confectioner a real production line (Figure 9), which is one example among many. The application is a standard praline bar with a soft “bloom-critical” filling inside and a dark chocolate shell.All the praline bars were produced one week before the test was start- ed and all pralines were glossy and free from any bloom. The pralines were divided into two batches and unwrapped. • Reference batch is kept for 24 h at 20°C before it is stored in 15°C and 23°C isothermal bloom test cabinets • Test batch is kept for 24 h at 25°C before it is stored in 15°C and 23°C isothermal bloom test cabinets Other examples are tests made where some FrozenCone (FCT) shells are heat treated before the filling is deposited. Some dark praline shells are made on FCT pilot equipment. Cooling is 3 seconds at 15°C and the shell thickness is 1.5mm.Afterwards all shells are cooled for 20 minutes at 12°C and then divided into two batches. Batch 1, reference • Shells are filled with a nougat filling with high amounts of hazelnut paste • Cooled for 15 min at 12°C • Backed off and then cooled at 12°C for 30 min. Batch 2, test samples • Shells are stored for 30 min at 30°C • Filled with nougat filling with high amounts of hazelnut paste • Cooled for 15 min at 12°C • Backed off and then cooled at 12°C for 30 Batch 1, Reference Batch 2, Test Samples 20°C for 24 hrs 25°C for 24 hrs 15°C isothermal cabinet 7 weeks, strong bloom > 25 weeks, no bloom 23°C isothermal cabinet 9 weeks, strong bloom > 25 weeks, no bloom Figure 9 min
The above two examples show how two different heat treatments at different production stages are able to compensate for some production “fault.” The first examples (Figure 9) show that even a one-week-old product is still able to be “re- paired” by heat treatment, probably by a Form V purification. It is the same phenomenon as seen in the earlier example (Figure 6) with ha- zelnuts in milk chocolate where migration happens but there is no visible bloom. The example in Figure 10 is slightly more complicated with two variants in the trial—the heat treatment and the storage time of the shell before filling. Dsc analyses show that the dsc melting peak and end set of the shell increase around 0.3°C when the shell is heat treated as mentioned for batch 2, but only between a third to a half of this increase in peak/end set value is caused by the extra 30 minutes’ storage time. The re- mainder is due to the higher temperature (heat treatment) applied. The conclusion is that this 30-minute pe- riod at 30°C makes a significant difference to the shelf life, caused by some changes in the shell, maybe purification of Form V crystals in the chocolate shells (which is supported by the slightly higher dsc peak values) and/or a type of aftertempering with longer residence times. Tests have been done using microwaves as a fast online heat treatment method instead of using longer times in heat cabinets. It is possible to find the correct combination of energy and time to delay bloom development by using <strong>Beat</strong> <strong>Migration</strong> <strong>Bloom</strong> by Optimizing Your Process microwaves early in the production process but very difficult to control. The optimal energy level and time is a ques- tion of recipes, applications and fat composi- tions. SUMMARY No two cases are the same with respect to migration bloom development.The application is too complex, therefore, it is important to look at all factors influencing migration bloom development before changing recipe, application and process parameters, for example. The above examples show that the process is a major factor as regards fast migration bloom in chocolate products. Results from Heat-treated FCT Shells—Filled Praline Shells A nonoptimal tempering process combined with a too high cooling rate favor a final crystallization mix of Form IV and Form V and that is probably the most common reason for fast migration bloom.The transformation of some fat from Form IV to Form V together with oil migration seems to have a larger influence on the development of migration bloom than expected. Even though a chocolate shows a well-tempered curve, it does not guarantee the production of Form V seeds.The effect of heat treatments shows that the chocolate is not perfectly tempered and it is possible to purify the crystal polymorphism even in a well-tempered chocolate shell, adding more bloom stability as a result. It’s also important to realize that changing the fat composition of a filling recipe will not solve this process problem but only help to delay it. The objective is always to start with perfect tempering at the highest inflection point level Batch 1, Reference Batch 2, Test Samples 20°C isothermal cabinet 9 weeks, strong bloom > 25 weeks, no bloom 23°C isothermal cabinet 7 weeks, strong bloom 25 weeks, strong bloom Figure 10 A nonoptimal tempering process combined with a too high cooling rate favor a final crystallization mix of Form IV and Form V, probably the most common reason for fast migration bloom. Reprint from The Manufacturing Confectioner • May 2010 7
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Beat Migration Bloom on Chocolate Products by Optimizing ... - AAK

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