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Chocolate Making: A Delicious Business

Chocolate is among the most popular non-essential food items globally [1]. An essential ingredient of several delicacies such as candy bars, milk shakes, cookies, and cereals [2], it makes a particularly important component for puddings, cakes, brownies, and other desserts [3].

Before it gets to the dining table, the chocolate has literally travelled around the world. The journey of chocolate begins on the evergreen cocoa trees located in the equatorial and tropical regions of South America, Mexico, Africa, and Southeast Asia.

After manually harvesting cocoa beans, workers ferment and dry them. Fermentation turns them brown and drying reduces their weight to half [2]. Next, cocoa beans are shipped to manufacturing facilities where they are roasted, winnowed, ground, and blended to form the chocolate we are familiar with [3].

From Roasting to Wrapping

Manufacturers first clean the beans to remove unwanted material. Next, they roast and winnow the beans to obtain the edible part called “nib,” which is the edible part of the bean.

Thereafter, they melt the nib, and add sugar and flavor to it. The liquid chocolate so produced is either stored or molded into the required solid form [2].

Let us examine each stage of the manufacturing process in detail:

  1. Roasting: is the important first step and plays several important roles:
    • Brings out the taste and flavor because it is the roasted cocoa beans that taste like chocolate, not the raw ones [4]. Typical cocoa bean color and aroma develop around 130-1500C [5].
    • Sterilizes the bean, eliminating any bacteria, molds, and fungi that are widespread in the tropical equatorial regions – the home of cocoa beans [4].
    • Simplifies cracking and winnowing by disconnecting the inner bean from the outer husk [4]. Roasting makes the outer cocoa shells brittle, making it easy to separate them [2]. Breaking down the inner cocoa bean gives tiny cocoa nibs [2].
    • Reduces moisture content from around 7% to about 1% [1]. This is important because chocolate and water do not mix. Lowering moisture simplifies grinding [6].
      For effective roasting, three conditions are essential viz. transfer of heat to the bean, smooth airflow in the roasting drum, and cooling [7].
  2. Winnowing: involves delinking the husk (outer shell) from the nib (edible part) of cocoa beans. The process directly impacts the final quality of the chocolate as better separation delivers top quality [8]. Any residual husk will introduce unwanted tastes [9]. Winnowing takes off 20-25% of the roasted beans’ weight [9].
    Equipment for winnowing cracks open the outer husks, which are then segregated from the nib by multiple stages of sieves (filters). Air blowing fans complete the separation as husks are lighter than nibs [10].
    Roasted beans are cracked open by passing them through serrated cones [11] or screw motion [10]. Vibration mechanisms may also be employed in addition to filters and fans for superior separation [10].
  3. Grinding: passes nibs through rotating metal drums to convert them into liquid called chocolate liquor [1]. Nibs contain 50-55% cocoa butter [12], which is a crucial ingredient for making chocolate.
    Depending on the requirements, manufacturers utilize three or even more grinding stages [12]. The roller speed rises in every successive stage [12]. Eventually, the size of chocolate liquor particles is crushed to 0.0254mm [1].
    From the middle of the grinding stage, the process handles liquid chocolate and this continues till step 8 i.e. molding stage.
  4. Separation: involves the use of hydraulic press [11] or rollers [1] to hike the pressure on chocolate liquor. This makes most of the cocoa butter inside the chocolate liquor flow out as a yellow liquid. The residue is the press cake and is processed into cocoa powder [1].
  5. Blending: manufacturers add cocoa butter to the press cake [1]. The quantity of added cocoa butter influences the consistency and texture, and, therefore, determines the type of chocolate produced [1].
  6. Conching: is the most critical stage in chocolate production [1]. Operating somewhat similar to eggbeater, the machine paddles move to and fro through the chocolate mass slowly to mix it thoroughly and aerate it [11]. Such action further reduces the chocolate particles’ size and removes any minor, residual bitterness.
    Process speed and temperature influence the quality of chocolate [1]. Other determinants of quality are the speed at which other ingredients (sugar, milk powder or milk, cocoa butter, flavors etc.) are mixed and when they are added [1].
  7. Tempering: is the slow cooling of the conched chocolate. Such machines can have heating and cooling mechanisms as well as mixers to maintain the molten chocolate’s homogeneity [13].
    Steady temperature drop in tempering imparts stability to the chocolate [14] i.e. prevents the ingredients from separating on solidification – when poured in molds for example [11].  It also maintains the chocolate’s crisp texture and luster [11]. It is the tempering stage that prevents chocolate from melting when people touch it [14].
  8. Molding: is the pouring of liquid chocolate into molds designed to provide the specifically shaped chocolate. Types of chocolates are pure chocolates, wafer or cookie including chocolates, raisin or dry fruit containing chocolates, or those with a core containing different materials such as jelly [15].
    Totally automatic, semi automatic, and manual are the three types of mold machines based on the level of automation [15].
    Stage 8 i.e. molding starts with liquid chocolate and ends with a solid one. Hereafter, all stages deal with solid chocolate.
  9. Wrapping: protects the chocolate from contamination while also lending it a catchy appearance and enabling the makers to brand their produce. After loading the wrapper material and chocolate (of the required size and shape) in the wrapper machine, the machine wraps the chocolate, cuts the wrapper, and seals it. Thereafter, the wrapped chocolates are packaged into cartons [16].
    Types of wrapper machines are Bar Wrapper, Coin Wrapper, Foil Wrapper, and Fold Wrapper. Different ways a chocolate is wrapped are Banding, Fold Wrapping, Foil Wrapping, Pleat Wrapping, Sleeve Wrapping, Twist Wrapping, and Foil and Band Wrapping [16].
    Chocolates can be wrapped as much as five times viz. primary, double primary, secondary, tertiary, and final wrappings [16].
    Molding machine is an auxiliary to the wrapping machine [15]. Equipment that serve as auxiliaries to both machines are [16]:
    • Tempering Machine
    • Chocolate Pump
    • Nut Feeder
    • Chocolate Enrober
    • Biscuit Feeder
    • Automatic Demolder
    • Feeder Mixer
    • Auto Chocolate Depositor
    • Chocolate Analyzer
    • Granule Doser
    • Granule Mixer
    • Weighing-Filling Mechanism

Finally

A process as long and complex as chocolate making demands diligent focus from the involved people and machines. Automation is a great way to make the process precise and fast.

Cybernetik Technologies has delivered customized automation and equipment solutions for the chocolate industry that enable close monitoring and control over each stage to make exceptional quality chocolate.

Contact us at +91 20 6790 9600 or sales.automation@cybernetik.com to feel the joy of made-to-order solutions.


References

  1. Chocolate, Advameg.
  2. The production of chocolate, Simon Fraser University.
  3. Chocolate, Wikipedia.
  4. Cocoa Bean Roasting, Chocolate Alchemy.
  5. Cultivation, Preparation & Roasting the Cocoa beans, Ritter Sport.
  6. An Introduction To Cocoa Roasting, XTC Chocolate.
  7. Cocoa Roasting Machine, Coffee Direct Pro.
  8. Cocoa Bean Winnowing, Oklahoma State University.
  9. Making Exceptional Chocolate: Winnowing Cocoa Beans, Wild Mountain Chocolate.
  10. Winnowing, Nemisto.
  11. How To Make Chocolate: From Cacao Bean to Chocolate, The Gourmet Chocolate of the Month Club.
  12. The Nib-grinding Process, The Manufacturing Confectioner.
  13. Tempering, ProBake.
  14. Tempering Chocolate, Ghirardelli.
  15. Chocolate Moulding Machine, SaintyCo.
  16. Chocolate Wrapping Machine, SaintyTech.

Natural by Design

Robots are not a new entrant in the food industry. They have handled palletizing and packaging jobs with speed and efficiency. It is only with the recent advances in gripper and vision technology that they are foraying into secondary food processing.

Managing sturdy or even the not-so-delicate parts is not a big task for robots. What is challenging is dealing with handle-with-care parts [1]. Take fragile foodstuffs such as raw eggs, soft chocolates, or strawberries for example. Or odd shaped apples and pears.

Quality and Speed are the two pivotal benefits of automation [2]. Employing conventional robots will damage these foodstuffs, and negate the quality advantage. In their mission to get over this barrier, robotic engineers turned to nature and came up with a simple yet excellent solution – the bionic gripper.

Nature has always triggered engineering developments. Bionics or engineering modelled on biology or living creatures [3] goes back centuries [4]. Jack Steele conceived the term bionics back in 1958 to describe engineering based on biology [5].

Japan’s Shinkansen trains for example employ the design of the Kingfisher’s beak to avoid sonic boom. Whale fin contours are the basis for the quieter, more efficient wind turbines with serrated edges [6]. And, there was the Gator Sharkote project that studied shark shin to develop an anti-fouling coating [7].

Robots & Grippers

Robots utilize two types of end effectors viz. grippers and tools. Connected at the robot wrist, they are usually custom built for specific operations. End-of-Arm Tooling (EOAT) is among the principal robot parts because it comes in touch with the part [8].

Grippers are generally involved with loading-unloading operations. One area where robots have an edge over manual labour is that they cause minimal damage to the handled part – the quality advantage of automation. But this advantage materializes only with the proper design and fabrication of gripper [8].

Robots utilize four main types of grippers [8]:

  • Vacuum Grippers are flexible, making them a standard EOAT. Polyurethane or rubber suction cups or closed cell layer of foam rubber acts as the pickup mechanism.
  • Hydraulic Grippers deliver up to 2000 psi gripping force, but are prone to oil leakages and maintenance issues.
  • Pneumatic Grippers are small sized and lightweight.
  • Servo-Electric Grippers use electronic motors for better control over gripper jaws. Plus, they are cost effective and can operate with varied material tolerances when working with parts.

Bionic Grippers

From the far reaching tentacles of the monstrous octopus and the mighty trunk of the colossal elephant to the sticky foot pads of the humble gecko lizard, nature presents countless examples for robotic engineers to derive inspiration from.

Festo’s Nano Force Gripper requires energy only to initially grip the object, not to maintain its hold. Located on the underside of the gripper is Gecko Nanoplast, a tape with 29,000 gripping members per square centimetre (cm2). Similar to suction cups, the gripping elements borrow their concept from foot pads of the gecko lizard [9].

Compressive force is applied on the tape to release the held part. The force reduces the size of the holding surface to a point where the part is smoothly released. Release action is based on the Fin Ray Effect, wherein the ends of a flexible structure bend towards the direction of a compressive force applied to its middle [10].

Four Fingers Lip by The Gripper Company has solid fingers for flexibly gripping parts and reinforced fingers for holding parts with greater force. With elastic material construction for smooth handling, the gripper has serrated tips for superior gripping of wet parts [11].

Ingrained self-compliance means the gripper can smoothly yet firmly handle parts of a whole range of size and shapes. Plus, it is available in three different configuration modules that allow eight different configuration builds for diverse utilization capabilities [11].

Tentacle Gripper is patterned on the octopus. Festo has made this gripper from silicone with suction cups in a double row formation lining the internal surface. Pumping compressed air bends the gripper towards the inside, enabling it to smoothly grip the part. And its soft structure allows it to assume the shape of the part [12].

Vacuum-actuated larger suction cups are actively involved in gripping. The smaller cups towards the gripper tip are passive. Coupled with its soft, pliable structure, the suction cups empower the gripper to grasp parts of umpteen shapes [12].

Gripper Selection & Productivity

Regulations dictate the use of grippers certified as food grade. EC 1935/2004 regulation deals with such grippers for use in Europe. The corresponding certification in the United States is FDA 21 CFR [13].

Soft grippers are best suited for handling random shaped, delicate foodstuffs. Vacuum grippers are better reserved for sturdier applications such as handling food boxes and beverage cans, as well as for palletizing solutions [13].

For maximum productivity and minimal downtime, use grippers that are [13]:

  • Compatible with the existing robotic set up.
  • Certified.
  • Suitable for dishwasher cleaning.
  • Of the required payload capacity.
  • Easy to replace with other grippers.

Finally

Robotic workspaces are moving towards zero separation and maximum collaboration between humans and robots. Festo’s BionicSoftArm robot, for example, eliminates the need for a safety cage. Based on the elephant’s trunk, it does not hurt technicians even in case of collision [14].

With the soft, human touch built into them, bionic grippers hold great potential in the times to come.

Cybernetik Technologies has successfully provided customized robotic automation solutions for the Food, Pharma, and Automotive industry since 1989.

Get in touch with us at +91 20 6790 9600 or sales.automation@cybernetik.com and harness the quality, speed, and productivity advantage of automation.

References

  1. 7 Types of Robot Grippers and their Industrial Applications, Ramon Ruiz, Ennomotive.
  2. Adaptive Gripper: Bionic Robotic Handling Solution.
  3. Bionics.
  4. Biomimicry: A History, Wyatt Schreiner, eHistory.
  5. When was Bionics Discovered.
  6. Biomimicry: 9 Ways Engineers Have Been Inspired by Nature, Donovan Alexander, Interesting Engineering.
  7. How Biomimicry & Other Innovations Will Make Ecoship the Greenest Cruise Ship, Kemplon Engineering.
  8. Grippers for Robots.
  9. Bionic Grippers for Automation, Control Engineering.
  10. The Fin Ray® Paper Kit.
  11. The Four Fingers LIP.
  12. Tentacle Gripper.
  13. New Robotoc Grippers Transforming the Food Sector, Kristian Hulgard, Robotics Tomorrow.
  14. BionicSoftArm.
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