Chocolate Behavior — What Influences Your Selection?

Marlene B. Stauffer The Blommer Chocolate Company

hocolate behavior—what do we mean ing, enrobing, hand-dipping, one-shot Cwhen we say this? How does chocolate depositing, panning or for the manufac- act in the many processes used in the con- ture of chocolate chips? fectionery industry? I will be touching on The chocolate type in any application some of the issues that relate to changes in needs a balance between the chocolate and As quality control chocolate behavior and that influence your the center. Milk chocolate can stand on its own and goes well with peanut butter, manager at Blommer, chocolate selection. Stauffer is responsible What issues need to be considered for caramel, nuts and inclusions. White cocoa for quality assurance, chocolate selection based on application butter based chocolate coating with just a product development, hint of chocolate aroma is often used for technical services and and what influences chocolate behavior in contrast in boxed goods or for its rich dairy, employee training. She these applications? What should we be vanilla flavor. Dark chocolate is more robust has been with the com- looking for? Many of these issues have pany since 1982. and aromatic and pairs better with tart fruits, been talked about before, but I want to strong coffee, liqueurs and mint centers. Stauffer is currently a try to give the practical aspects of why member of AACT and Compound coatings are used for their cost, chocolate acts the way it does. IFT, and is a board functionality and support in confections. member of PMCA. Viscosity, or how the product flows, is CHOCOLATE SELECTION key to many confectioners when selecting First, let’s talk about chocolate selection. a chocolate. The correct flow properties The main issues to consider when selecting influence how the product will work in the a chocolate are application, chocolate type, given application. viscosity, fineness, color and flavor. Each of Fineness selection is typically based on these items has an influence on how the fin- what the chocolate will be used for and ished piece will appear to the consumer. what market is being targeted. For example, The first consideration is the chocolate if a smooth, creamy center is being coated, application. Is it for hollow or solid mold- one could easily be distracted if a coarse Marlene Stauffer

The Manufacturing Confectioner • September 1998 75 Chocolate Behavior

Since our first coating is used. On the other hand, a coarse temperature, using a specific bulb diameter taste of any food coating would not be noticed on choco- and depth. It gives a number indicating late containing noisy inclusions such as how thick or thin a product is, but does is with our eyes, crisp rice, oats or nuts. not tell a lot about the flow characteristics the color of a The next item to be considered in choco- of the product. This is not as commonly chocolate gives late selection is color. Since our first taste used today, but the original numbers gen- us some of any food is with our eyes, the color of a erated from this method are still referred to indication of chocolate gives us some indication of what when selecting a specific coating. For exam- to expect. Color is determined by the type ple, a 65 viscosity refers to hollow molding, what to expect. and amount of chocolate liquor, sugar and a 145 viscosity might be used for enrobing dairy ingredients in a chocolate coating, and a 200 viscosity for solid molding. hence formulation. The Brookfield viscometer or rheometer Flavor is often considered to be the can give MacMichael numbers, but it can determining factor of whether or not a also give a more complete measurement of product will make it in the market. The the chocolate performance or flow prop- correct balance of acceptable attributes erties. Brookfield and Haake take a sample helps to determine the success of any prod- at a specific temperature and then readings uct. There are some 9,000 taste buds on are taken at increasing rates of shear rang- the human tongue, each containing 15–18 ing from 1 to 50 rpm, followed by similar sensory cells. Flavor perception and pref- readings at decreasing speeds. Using Cas- erence might be completely different from son’s calculations, viscosity is determined. Rheology is defined as the study of the one consumer to another, so pleasing flavor deformation and flow of matter with stress. is definitely an important issue for the cor- Viscosity is the name given to the internal rect chocolate selection. friction of fluids. Essentially, there are two CHOCOLATE BEHAVIOR types of liquids — Newtonian and non- Newtonian. Newtonian fluids are inde- What determines behavior of chocolate or pendent of shearing. Examples would be how the chocolate will perform? Following water, alcohol, liquid fat or glycerol. are some factors determining the behavior Chocolate is non-Newtonian and its vis- of chocolate: cosity is affected by the presence of solids • Product flow in suspension. Chocolate is often referred • Fat content to as a suspension of particles in a fat phase. • Particle size and distribution Therefore chocolate viscosity will decrease • Equipment with increasing rates of shear. This is why • Moisture the Brookfield and Haake rheometers will Let’s concentrate on flow properties of give more accurate measurements of flow chocolate and particle size due to their properties due to procedural shearing at a great influence on chocolate behavior and given rpm indicating a product’s resistance also chocolate selection. to flow.The MacMichael will not be able to shear the entire sample between the gap Viscosity and the wall of the sample cup; it is only Viscosity is a measurement used to describe measuring the torque at a given rpm.Think the flow properties of a product. Some ways of the friction created when sliding a deck of measuring viscosity are the MacMichael, of cards back and forth or the friction cre- Brookfield and Haake methods.All of these ated between sugar and cocoa particles in methods are used in industry today, with a fat phase.These products need a force to Brookfield being the most common. start them to flow. This is known as yield The MacMichael is a single-point sys- value. More specifically, the yield point tem. The product is measured at a specific should be redefined as the shear stress at

76 September 1998 • The Manufacturing Confectioner Chocolate Behavior which not only deformation occurs but sta- (>0.5 percent). Polyglycerol polyricinoleate It is best to add tionary flow begins. (pgpr) and ammonium phosphatides lecithin as late in (yn)— manufactured from rapeseed oil — Yield value is reported in dynes/square the process as centimeter. Plastic viscosity is then the are also known to greatly reduce viscosity. force needed to maintain this flow once it Their usage depends on the legislation of possible so it is moving, which is known as poise. Brook- the particular country. does not bind up field can measure these values, known as Percent moisture, fat content and par- moisture. Casson values.Yield value has a number of ticle size also influence yield value. Figure practical aspects. For example, a high yield 1 shows a comparison of percent fat in value is needed for drops so the curl will chocolate, plastic viscosity, yield value stand up on the drop and not produce a and MacMichael number.As you can see flat-looking drop like a disc. Also, a high in Figure 2, the yield value and plastic vis- enough yield value is needed in enrobing to cosity for solid items are the highest. The prevent decorations from collapsing and yield value and plastic viscosity decrease to avoid feet formation on the bottom of with increased fat, which would correlate pieces, in other words, so chocolate will to different applications in confectionery flow over the piece and not off the center. manufacturing such as enrobing, hollow A lower yield value is desired for molding, items and panning.Actual values for yield especially with inclusions, so proper shake- value and plastic viscosity need to be determined based on what will work best out can occur and removal of air pockets is in your specific application and equip- successful. A low yield value is also desir- able for enrobing bakery items. Percent Fat versus Viscosity Measurement

26% 27% 30% 34% Yield Value Influences 180 Proper emulsification in the chocolate 160 140 mass is necessary to aid in yield value 120 reduction. Lecithin was introduced to the 100 80 industry over fifty years ago. It is primar- 60 ily extracted from soybean oil. Lecithin 40 has both lipophilic (fat loving) and 20 0 hydrophilic (water loving) properties.This Plastic Yield MacMichael surface-active agent greatly affects choco- Viscosity Value late fluidity. The degree of flow is depen- Figure 1 dent on the ease with which the solid par- ticles are able to move over one another Viscosity at Various Fat Percentages 140 Four samples within the liquid phase, which is cocoa YV butter. Lecithin is an economic value to Decreasing yield value with 120 PV chocolate due to the ability to manufacture added fat 26 percent solid items chocolate with less cocoa butter.The time 100 27 percent enrobing and amount of lecithin is critical for its 30 percent hollow full effect on changing viscosity. It is best 80 34 percent panning to add lecithin as late in the process as 60 possible so it does not bind up moisture and maximum cocoa butter has been made 40 available through the conching process. 20 An addition of 0.1–0.3 percent has the same viscosity-reducing ability as ten times 0 the amount of cocoa butter. Too much 26 27 30 34 Figure 2 lecithin will cause the viscosity to increase

The Manufacturing Confectioner • September 1998 77 Chocolate Behavior

If the particle ment.An experimental design might be to fine the chocolate needs to be. size distribution measure the plastic viscosity and yield Laser light-scattering measuring equip- ment has been developed and is widely shows large value when a product line is operating within tolerating limits. This way you can used for determining the particle size dis- amounts of fines develop a range of values that will work tribution of a mass. This will identify the in the analysis, for the given application. Working with size and amount of all particles within more cocoa manufacturers of ingredients and equip- the determining range of the instrument. butter will be ment will also help this be successful.The The mass is suspended in a surfactant and injected into the unit. Particles will dif- needed to get to following issues also influence the flow- property behavior of chocolate: fract the laser beam at different angles a specified Temper — the lack of control of temper depending on their size. The laser beam is viscosity. can destroy any specifications already set focused on a field of particles and then for plastic viscosity and yield value. the angle of diffraction is observed. Vibration — this is needed to remove excess Smaller particles diffract light at wider chocolate and air bubbles; it is the level of angles and different intensities than larger vibration that is important, based on the particles. This type of analysis can tell us yield value of the product. the distribution of the particles, informa- Method of manufacture — whether the tion that is needed to evaluate fat require- product is one-stage or two-stage refined. ments, yield value and mouthfeel. Degree of conching — releasing the most Let’s look at these three issues with respect to particle size. Cocoa butter is the available cocoa butter for viscosity reduction. most expensive ingredient a chocolate man- Particle Size ufacturer has in a chocolate formulation. If the particle size distribution shows large Next, let’s look at particle size and distri- amounts of fines in the analysis, more cocoa bution and how they can influence choco- butter will be needed to get to a specified late behavior. We have already discussed viscosity.This difference in grind could be how particle size can influence our selec- related to equipment used to manufacture tion of a given chocolate for the applica- the chocolate. tion and the sensory experience, so let’s Single-stage refining, for example, will look into what this means when we talk give more fines than two-stage refining, as about chocolate performance.A particle is shown in Figure 3.The amount of fines will any object having definite physical bound- contribute to more surface area and create aries in all directions without respect to a system that will need more fat to coat all size.Traditionally, fineness (how coarse or of the particles. On the extreme, large fine) of chocolate was determined by a amounts of coarse particles will contribute handheld micrometer measuring only the to a lower fat content. A bimodal particle largest particle in the sample. The choco- size distribution is what the chocolate man- late is mixed with mineral oil and placed ufacturer is looking for due to different on one anvil of the micrometer.The anvils particles having different strengths and are then closed to a certain pressure to breaking down differently. give a fineness in either ten thousandths of In a paste to be refined, there are par- an inch or in microns. This method mea- ticles of chocolate liquor, sugar and pos- sures the diameter of some of the larger sibly milk.The chocolate liquor will most particles in the chocolate. This is used to likely already be ground to release avail- evaluate refining grade if the primary con- able fat, therefore, particles to be ground cern is mouthfeel. It does not, however, by the refiner are sucrose and milk pow- describe anything about the size, shape or der. Sucrose particles are typically ground amount of fine particles. This number is by abrasion (friction) and milk powder still used today to specify how coarse or principally by fracture (rupturing cells).

78 September 1998 • The Manufacturing Confectioner Chocolate Behavior

It is important to Single-stage versus Two-stage Refining

100 5 100 5 select the 90 90 80 4 80 4 chocolate that 70 70 complements 60 3 60 3 50 50 the end product 40 2 40 2 DIF VOLUME DIF VOLUME % DIF VOLUME DIF VOLUME % CUM VOLUME CUM VOLUME % CUM VOLUME CUM VOLUME % 30 30 to be 20 1 20 1 10 10 manufactured. 0 0 0 0 0.1 1 10 100 1000 0.1 1 10 100 1000 MICRONS MICRONS

Single-stage Two-stage Figure 3

Due to these differences, a bimodal par- Typical Fineness Values ticle distribution will be seen during refin- Microns ing. Because of this, some fine particles are Truffles 10–15 needed to fill the voids created by the Boxed goods 10–20 larger particles, referred to as packing Solid bars 10–25 Panning 15–30 efficiency. The total fat content can be Chocolate chip 15–35 altered by this particle packing. If particles Inclusions 20–40 can pack tightly, not as much cocoa butter Hollow 15–45 will be required. Figure 4 Yield value in products is also directly also issues in chocolate behavior—mainly affected if the particle size distribution is flow properties and particle size. It is impor- altered. It will pretty much be changed the tant to select the chocolate that comple- same way when total fat has to be ments the end product to be manufactured, increased, as shown in the discussion on and decide the quality parameters neces- flow properties.There are times and certain sary together with the ingredient and applications that are ideal for generating equipment manufacturers that will best more fines, to help increase yield value. meet your needs.The final evaluation of the Mouthfeel may not be considered a chocolate, of course, will be in the actual behavior of chocolate, but it does influ- piece intended for consumption. So go ence how the product melts in your mouth. forth, with ideal chocolate behavior, and Typical fineness values shown in Figure 4 make sweet confections! give an idea of what specifications might be required for mouthfeel. This is more for REFERENCES what the palate will detect. Most individu- Beckett, S.T. Industrial Chocolate Manufacture als will not detect particles less than 20–25 and Use, Blackie & Son Ltd., NY, 1988. microns on their tongue. Fischer, B.J., A. Zuritz, G.R. Ziegler. Particles When the amount of fines — meaning Size Distribution and Rheology of Molten Semi-Sweet Chocolate. AICHE, 1994. smaller than 10 microns —increases too Jackson, K. Chocolate: Defining the Need. much, you will get a gummy or clawing feel PMCA Production Conference, 1996. in your mouth similar to peanut butter.This Minifie, B.W. Chocolate, Cocoa, and Confec- could be objectionable and would need to tionery. Third Edition, Van Nostrand Rein- be considered for the specific application. hold, NY, 1989. Monigia, G., G.R. Ziegler. Controlling the Flowability of Molten Chocolate with its CONCLUSION Particle Size Distribution. Penn State Uni- ■ As you can see, some of the issues in select- versity, PA. ing a chocolate for a given application are Presented at the AACT National Technical Session.

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