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 Why do these special heat or cooling treatments sometimes improve bloom stability in filled products? In general, it is a question of compensating for some defects in the basic production. DSC Peak Values Peak values Figure 4 33.5 33.4 33.3 33.2 33.1 33.0 32.9 32.8 32.7 32.6 32.5 Figure 2 shows that when making a temper test at a low cooling temperature the same chocolate would be undertempered if it had been measured at a higher cooling temperature, which actually is more similar to the temperature used in production lines. The lower the cooling temperature, the lower the inflection point, see Figure 3.The only ex- planation for this kind of lower inflection point for the same chocolate and lower values for dsc peak (Figure 4) must be the different ratio between Forms IV and V in the final chocolate samples. The more the cooling, the more Form IV crystals are generated in the final chocolate. Pure Form IV crystals are very unstable and for that reason they will quickly transform into Form V depending on fat composition and tem- Peak value Linear (Peak value) y = 0.0622x = 32.17 R² = 0.92 7 9 11 13 15 17 19 Cooling temperature °C Cooling Rates vs. Melting Peak Values Cooling Peak value °C Rates melting curve 28°C –> 15°C 32.3 Rate 0.3°C/min 10 min at 15°C 15°C –> 60°C with 5°C/min 28°C –> 15°C 32.0 Rate 0.5°C/min 10 min at 15°C 15°C –> 60°C with 5°C/min 28°C –> 15°C 31.6 Rate 1.5°C/min 10 min at 15°C 15°C –> 60°C with 5°C/min Figure 5 4 May 2010 • Reprint from The Manufacturing Confectioner perature. Smaller amounts of Form IV crystals in mixtures with a lot of Form V will probably make the chocolate unstable, too, but how much probably depends on the ratio between the two polymorphs and the above-mentioned factors. Nobody knows how much Form IV “contamination” you can have in a chocolate without influencing contraction, gloss, etc. Figure 5 shows a well-tempered dark chocolate cooled on a dsc with three different cooling rates. The chocolate is tempered on a 50 kg three- zone tempering unit and a small sample is weighed into preheated dsc cups and placed in the dsc equipment. The samples are stored for 2 minutes at 28°C and then cooled with three different rates to 15°C, kept at 15°C for 10 minutes and then remelted at 5°C/min from 15°C to 60°C. The different values for the melting peaks are shown in Figure 5. These results show the same tendency as seen from the results mentioned in Figures 3 and 4. The faster the cooling, the lower the peak value and the wider the melting curves. SPECIAL HEAT OR COOLING TREATMENT Individual companies sometimes use different types of special treatment to optimize bloom stability. Some store in cool conditions for a week or more, others store in hot conditions for a few days up to one week. Why do these special heat treatments or special cooling treatments sometimes improve bloom stability in filled products? And why is this effect different from application to application and time to time? In general, it is a question of compensating for some defects in the basic production. It seems that a heat treatment compensates for
a tempering with some amount of Form III/IV formation and/or too fast a cooling of the chocolate where some Form III/IV formation happens afterwards. While alternatively a special “after” cooling compensates for too high a production speed and for that reason an insufficient remov- al of crystallization heat from the product before packing and an insufficient structure building in the filling. Often product is stored in rooms held at 12°C to 16°C. During this special cooling the TAG composition in fillings and shells has found its optimum network structure. <strong>Migration</strong> speed will be minimized and therefore the migration-induced bloom will be reduced. Again it is a compensation for insufficient cooling time in the production line and it actually takes much longer to remove all crystallization heat from a filling if it is in the center of a pallet and the risk of migration-induced bloom is higher than if the product had been cooled correctly at the start. <strong>Bloom</strong> Evaluation Results Weeks before visible migration bloom Special storage around nuts 1 week at 20°C, reference 29 1 week at 23°C 45 1 week at 25°C > 52 1 week at 28°C > 52 Figure 6 Chocolate without Heat Treatment Figure 7 <strong>Beat</strong> <strong>Migration</strong> <strong>Bloom</strong> by Optimizing Your Process The following example shows the effect of heat treatment on milk chocolate with whole nuts. A milk chocolate is well tempered and mixed with 10 percent whole hazelnuts. The mixture is deposited into 100 g moulds and cooled in a three-zone cooling tunnel (at 12°C, 10°C, 14°C) for 30 minutes, 10 minutes in each zone. After cooling, all the tablets are stored for one day at 20°C and then divided into four batches: • one batch is kept at 20°C for one week • one batch is kept at 23°C for one week • one batch is kept at 25°C for one week • one batch is kept at 28°C for one week After one week all tablets are placed in a 20°C isothermal cabinet for bloom evaluation. Re- sults from the bloom evaluation are found in Figure 6. Figures 7 and 8 show the difference between heat treatment and no heat treatment. The only production difference between the two tablets is the one-week heat treatment. An analysis of the TAG composition of the chocolate at a dis- tance of 0.5 mm from the nuts does not show a significant difference in the TAG composition. For both cases, migration of triunsaturated TAG (OOO) has taken place, but with two different bloom results. Chocolate with Heat Treatment One week at 20°C followed by 29 weeks at 20°C One week at 28°C followed by 52 weeks at 20°C Figure 8 It takes much longer to remove all crystallization heat from a filling if it is in the center of a pallet and the risk of migrationinduced bloom is higher than if the product had been cooled correctly at the start. Reprint from The Manufacturing Confectioner • May 2010 5
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Beat Migration Bloom on Chocolate Products by Optimizing ... - AAK

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