As the mother of Forrest Gump, played in the cinema by Tom Hanks, said: "Life is like a box of chocolates, you never know what you're going to stumble upon." But when it comes to making chocolate-based fillings, process control systems require much higher levels of confidence. These can be guaranteed with the latest in-line refractometers from Vaisala (Finland), which are used at different points in the process, delivering continuous measurements of the concentration of TS (total solids) or degrees Brix (dissolved solids).
Online refractive index (IR) monitoring, with automatic feedback control and alarms when measurements approach alert levels, allows process operators to ensure a consistent and reliable product, so that ongoing production complies with regulatory requirements and product specifications. This technology finds its application in a wide variety of sectors, including in the field of process monitoring associated with the sugar and chocolate filling industry!
Quality control of the manufacture of luxury pralines
Vaisala is a global specialist in meteorological, environmental and industrial measurement. One of its customers, a chocolate manufacturer known as "Quality First", has invested in Vaisala K-Patent sanitary refractometers to continuously monitor Brix degrees as part of the final quality control.
At the heart of the pralines is a cherry dipped in a cherry-brandy liqueur and covered with a generous coating of dark chocolate. Known internationally, the brand packages its pralines individually.
The chocolate manufacturer uses Vaisala refractometers for quality control of the liqueur; the objective is to ensure that the production strictly meets the recipe. Alcohol is added to the brandy to achieve the desired concentration of liquor, and measurements in Brix degrees are taken immediately before the phase of adding the brandy to the cherries.
Areas for the production of products with a high alcohol content must be at least Zone 2 environments certified in accordance with the Atex Directive. Thus, in addition to the fact that the monitoring device is approved for sanitary applications, it must also have an Atex classification. In this case, it was necessary that the refractometer be intrinsically safe and comply with the requirements of zones 0/1 with Atex certificate. Vaisala's solution therefore combines compliance with both the 3-A health regulations and the European EHEDG standard + Atex zone 2, 1 or 0 certification.
Prior to the installation of Vaisala refractometers, testing was performed by manual sampling for laboratory analysis. This was both costly and time-consuming, resulting in delays in the disclosure of test results. Any deviation from specifications could therefore result in the loss or waste of products. Now, with online monitoring, problems are detected immediately so that appropriate action can be taken immediately.
There are two types of cocoa powder. Natural, brown and naturally acidic cocoa powder (pH 5 – 6), and solubilized cocoa powder, or "alkalized cocoa powder", which is made from cocoa beans treated with an alkaline solution to neutralize their acidity. Alkalization produces a variety of cocoa powders that can be used in different applications. However, the qualities of alkalized cocoa powder are significantly affected by the type and concentration of alkali, so Vaisala K-Patents process refractometers are used to ensure that the process falls within precisely defined concentration limits and meets specifications.
At the end of fermentation, the cocoa beans are cleaned and usually broken into pieces, also called "cocoa grué", before making chocolate or cocoa products. Regarding the alkalization process, the size of the cocoa particles is further reduced and the cocoa clump is then mixed with an aqueous alkaline solution.
The alkalinization process is done in a closed double-walled tank at about 120 °C. The total cooking time depends on many factors, including the alkaline concentration, the cocoa material to be processed and the temperature used, but it usually takes 10 to 30 hours. The alkalized cocoa powder is then removed and the grué is roasted, cooled to room temperature, crushed to form a chocolate liquor which is then pressed to remove the fat and generate a cocoa cake. The meal is then crushed, dried and sieved to obtain an alkalized cocoa powder.
The Vaisala K-Patents sanitary refractometer can be installed directly in the preparation tank of the aqueous alkaline solution to measure the concentration in real time. The refractometer can also be installed in a recirculation line, or directly in the tank.
Continuous measurement of the Brix level of the cooking solution
Chocolate sweets and fillings are produced by preparing a diluted mixture of ingredients and then concentrating the sugar content to the desired level during cooking and evaporation of water. The final Brix degree of the mixture determines the flavor, consistency and overall quality of the final product. Careful monitoring is therefore necessary to ensure consistent and reliable product quality.
Incorrect humidity can adversely affect the physical characteristics of the final product; causing upstream processing problems and affecting the quality of the final product. Excessive moisture can also lead to deterioration of the product by promoting the growth of microorganisms.
The Vaisala K-Patents sanitary refractometer continuously measures the Brix level of the cooking solution. It offers real-time information to determine the end point of cooking and to ensure consistent product quality.
The refractometer can be installed directly in the cooking cell or at its exhaust line. As part of a batch process, a recessed refractometer is installed at the bottom of the tank. As part of continuous cooking, the refractometer is installed at the evacuation of the cooking cell. A recessed refractometer can be installed in a cooking cell without hindering the action of scrapers or mixers, and the prism is cleaned with steam or high-pressure water from a cleaning nozzle installed with the refractometer.
Another refractometer can be installed at the premixer to ensure the desired flow concentration to the cooking cell. Continuous measurement is particularly important to ensure the continuous operation of vacuum cooking cells.
The refractometer provides Ethernet and 4-20 mA output signals for real-time process control. If the Brix degree at the end of cooking does not match the specified value, the refractometer sends a signal to the process control system regarding the valve control. For example, the control system opens the valve to recycle the product to resume processing and sends the information to adjust the proportion of ingredients.
One technology, many applications
Unlike many other methods of measuring liquid concentration, the Vaisala K-Patents refractometer is not affected by particles, bubbles, crystals or color. These instruments can therefore be used in many solutions to measure the concentration of liquids. What's more, Vaisala K-Patents refractometers comply with 3-A sanitary standards and are EHEDG certified. In addition to the confectionery industry, Vaisala refractometers are commonly used in various food and beverage applications as well as other sectors, such as semiconductors, chemicals and refining, pulp and paper, textiles and pharmaceuticals.
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