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 It appears that the process is the major part of many migration bloom problems and this opinion is supported by different investigations. A typical well-tempered chocolate contains approximately 2 to 4 percent Form V seed crystals when leaving the tempering unit; the Form V crystals just survive because of their higher melting point in this specific fat phase. An exception is a new technique that seeds with approximately 0.5 percent Form VI crystals, which ensures Form V crystallization in the remaining 99.5 percent cocoa butter and is stable enough to induce crystallization at a slightly higher temperature. The purpose of all tempering techniques is basically to start and ensure the Form V crystallization in a chocolate. If a chocolate is not seeded correctly with sufficient Form V crystals, the chocolate will crystallize in a lower form fol- lowed by transformation, resulting in problems such as poor contraction and bloom. Even producing a well-tempered (Form V) chocolate does not guarantee that the rest of the chocolate will crystallize in the same poly- morphic form. The outcome is highly depend- ent on process cooling and heat treatments. Too fast a cooling will favor Form IV crystallization even if the tempering has created perfect Form V seeds. Too much heat treatment will melt the seed. The application has a significant influence upon bloom. For applications with only one fat phase, such as solid bars or solid pralines, it is not very critical, whereas for applications with more than one fat phase, like filled bars and pralines, it is much more critical and much more difficult to understand. Applications containing more than one fat phase constitute perhaps 90 percent of all bloom problems and for that reason it is the most important problem to solve. It appears that the process is the major part of many migration bloom problems and this opinion is supported by different investigations. 2 May 2010 • Reprint from The Manufacturing Confectioner Tri-unsaturated tri-acylglycerols (TAGs) such as 1-oleoyl-2-oleoyl3-oleoyl-glycerol (OOO) accel- erate the transformation from Form V to Form VI and it is very likely that the same will happen with the Form IV to Form V transformation. The tri-unsaturated TAG, OOO, is the major TAG in many nuts, e.g., hazelnut, almond and peanut, and all are frequently used in many fillings in large amounts and migration bloom is often seen in this kind of application. In this paper, the focus is on the tempering test, tempering and the production cooling, especially for shell cooling. TEMPERING The traditional way of tempering is a process where all the chocolate is cooled to a temperature where the fat phase starts crystallizing in a mixture of Forms III, IV and V. This process is based on the possibility of remelting all Form III and Form IV crystals in a following reheating zone.Then, by testing the tempering curve on a standard instrument, it should be possible to determine the tempering conditions of the final chocolate. It is quite easy to evaluate the slope of a tempering curve but not as easy to evaluate the plateau level or inflection point of the curve. It is found that the plateau is correlated to the crystal stability and bloom stability of the chocolate.A lower crystallization plateau produces less stable crystals and a less bloom- resistant chocolate. The target for the inflection plateau must therefore be as high as possible for a certain chocolate composition. It is well known that the fat phase composition affects the inflection point level. More milk fat in a recipe, for example, produces a lower inflection point. This fact does not directly influence the purity of Form V seed crystals because it is possible to adjust for it. But when tempering
equipment is unable to make the high inflection level or there is ignorance about how important it is or how to change it, then it is much worse and more difficult to change. COOLING FOR TEMPER TESTERS AND SHELL COOLING Nearly all tempermeters use a cooling temperature somewhere between +7° and +10°C even though cocoa butter prefers gentle cooling to ensure Form V crystallization. Years ago an ice- and-water bath was used; this was even further away from “perfect” chocolate cooling. Tests carried out in our pilot laboratory on a dark chocolate using a standard tempermeter have shown a clear correlation between the chosen cooling temperature on the tempermeter and the inflection point level and slope for a certain chocolate (Figure 2). From Figure 2 it can be seen that as the cooling temperature in the tempermeter increases so does the slope. For example, the 17°C cooling temper ature gives a slope of +0.41, an indication of under- temper, that there is an insufficient quantity of Form V seed. To correct this, slightly lower cooling temperatures in the crystallization zones and slightly less heat in the heating zones of the temperering unit are needed. Figure 3 shows the correlation between the inflection point for the same chocolate as used in Figure 2 and the cooling temperature, but now the tempering unit has been optimized (see above) for each of the four cooling temperatures on the tempermeter. It seems that increasing the cooling temperature increases the inflection point of the chocolate.That indicates that more stable crystals are produced at higher cooling temperatures. In Figure 4 the well-tempered chocolate from the above tempering-test measurements is <strong>Beat</strong> <strong>Migration</strong> <strong>Bloom</strong> by Optimizing Your Process evaluated. After the tempering test is finished, the different chocolates are kept for 10 minutes at 15°C and refined on a grater and weighed into dsc (differential scanning calorimeter) cups and melted using the following program on a Mettler Toledo DSC 823: The temperature regime is 2 min. at 15°C and then 15°C to 60°C at +5°C/min. Figure 4 shows the correlation between the dsc peak values for the melting curves and the cooling temperature on the Exotherm equipment. It seems that the higher the cooling temperature, the higher the peak value, which indicates a purer Form V crystallization. Cooling and Temper Curve Slopes Temperature curve slope 0.6 0.5 0.4 0.3 0.2 0.1 Figure 2 Correlation of Inflection Point on Optimized Temper Unit Inflection point °C Figure 3 0 7 9 11 13 15 17 19 Cooling temperature °C 26.5 The influence of cooling temperature on the slope of temper curves 26 25.5 25 24.5 24 23.5 7 9 11 13 15 17 19 Cooling temperature °C Increasing the cooling temperature increases the inflection point of the chocolate. That indicates that more stable crystals are produced at higher cooling temperatures. Reprint from The Manufacturing Confectioner • May 2010 3
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Beat Migration Bloom on Chocolate Products by Optimizing ... - AAK

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