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Nestlé cocoa processing and chocolate manufacturing

Posted: 18 August 2008 | Klaus Zimmermann, Head of Product Technology Centres and R&D Centres, Nestec S.A. and Hilary Green, Head of R&D Communications, Nestlé S.A. | No comments yet

Nestlé Chocolate Processing Research and Development has a long 100 year history, and is an important part of Nestlé’s rich innovation heritage. The ‘grandfathers’ of Nestlé’s chocolate history were François-Louis Cailler, Charles-Amédée Kohler and Daniel Peter. The history of Swiss innovation in chocolate started in the 19th century with Daniel Peter’s invention of milk chocolate in 1875. The Nestlé label was used for the first time in 1904, following the merging of Kohler’s and Peter’s companies. Cailler’s company was subsequently added in 1911. We have come a long way since then.

Kit Kats

Today, Nestlé manufactures chocolate or chocolate compounds in more than 50 factories world-wide. The earliest was built in the 19th Century by Alexandre-Luis Cailler, the grandson of François-Luis Cailler, in Broc, Switzerland. Most recently, in November 2007 Nestlé acquired the Ruzskaya Confectionery Factory, which is one of Russia’s leading premium chocolate manufacturers.

Taste and texture

Chocolate meets a number of emotional needs, including pleasure, reward and sharing. The two characteristics of chocolate that help to meet these needs are flavour and texture. Like tea and coffee, the flavour of chocolate is largely generated during the immediate post-harvest phase. This is during the preparation and treatment of the cocoa beans, with additional flavours such as vanilla being subsequently added. Chocolate is uniquely characterised by a texture that is solid at room temperature but which melts at body temperature (37°C). Chocolate is a dispersion of fine sugar, cocoa and milk particles in a continuous fat phase. Therefore, chocolate processing has to take both taste and texture into account.

The consumer ultimately decides whether the chocolate he or she buys has the desired sensory properties. Therefore, qualitative sensory panel testing is an essential part of chocolate research and development. However, quantitative approaches to assess flow and friction in molten chocolate also have their place.

To this end, Nestlé has evaluated the role of rheological or tribological (interaction or friction between different surfaces) measurements to assess the viscous properties of chocolate (Lee et al, 2002). The main factors that influence these properties are the cocoa butter content, the lecithin content and the particle size distribution. Nestlé research has shown that tribological measurements are sensitive to the lecithin content of chocolate, regardless of particle size distribution, whereas rheological measurements are sensitive to lecithin only when particle size is small. By contrast, tribological measurements are sensitive to particle size only when the lecithin content is high, whereas rheological measurements are sensitive to particle size only when the lecithin content is low (Lee et al, 2002) These techniques therefore provide additional research tools for evaluating the sensory properties of chocolate.

More recently, Nestlé has contributed to a detailed review of factors that influence the rheological and textural qualities in chocolate (Afoakwa et al, 2007).This review highlights the need for further research to better understand how processing as well as particle size distribution, and ingredients, influence flavour and texture.

Chocolate processing

Most industrial chocolate is manufactured conventionally from cocoa mass, sugar and milk solids using the well-defined steps of mixing, grinding (refining) and conching (Beckett 1999; Beckett 2001). There are opportunities for research and development at each of these stages.

Good chocolate manufacturing starts even before the cocoa beans arrive in the processing factory. Preliminary fermentation and subsequent drying help to promote flavour. Once in the factory, the beans are cleaned and roasted. The beans are then broken into particles of a few millimetres in diameter and excess shell is removed. During the cocoa nib preparation, Nestlé Research has included an evaluation of the use of near infrared (NIR) spectroscopy for measuring the amount of shell-in-cocoa nibs and nibs-in-shell (Nzabonimpa and Aparicio, 1995). In this study, NIR spectroscopy was found to be an accurate alternative to existing methods. In making chocolate, it is important to have the right tools to ensure that a good quality of cocoa nibs is used.

In a later stage of the chocolate manufacturing process, the dry chocolate mixture (cocoa particles, sugar and cocoa butter or milk solids) is mixed and ground into fine particles. In a mechanised, high throughput factory setting, mixing and grinding is generally performed in two separate steps, with the major mixing step taking place in a tank, known as a conche. Conching is also important for further flavour development. During the conching process, chocolate is agitated in a conche for a certain period of time, typically between eight and 72 hours, depending for example on the amount of cocoa mass in the chocolate. A longer conching time is needed for dark chocolate compared with milk chocolate.

Conching is not only time consuming, but it is also demanding on energy. Nestlé Research has found energy savings of up to 32 per cent by using a reciprocating multihole extruder, in addition to the conche (Jolly et al 2003). Whilst generalisation of these results to other systems may not be appropriate, the results do provide data that show how the desired results of conching can be achieved more efficiently.

Quality

Nestlé is committed to quality throughout the chocolate manufacturing process. One example of where Nestlé Research is playing a role in ensuring quality is through its work in assessing authenticity in order to ensure label compliance.

In this regard we have assessed the feasibility of using the combined bulk stable carbon isotope and compound specific isotope analyses for identifying and quantifying the fatty acid profiles of cocoa butter (CB) and cocoa butter equivalents (CBE) (Spangenberg and Dionisi 2001). This approach allows us to distinguish the fatty acids in CB from those in CBE. This provides the means for ensuring that the labelling of milk chocolate meets the requirements of the European Union Directive 2000736/EC in which the amount and composition of permitted vegetable fats other than cocoa is prescribed.

Healthy options

While chocolate addresses consumers’ emotional needs, Nestlé R&D is also providing the scientific basis for providing healthier options. This includes but goes beyond providing smaller portion sizes.

A variety of additional processing technologies can be used to generate healthier chocolate options, including extrusion, sintering and aeration.

Extrusion technology is used to make confectionery not only from chocolate but also from cereals and fruit. This has been used to develop Nestlé Bocaditos in Latin America, made from corn, wheat and oat, which provide some dietary fibre. This product is also lower in calories than regular chocolate (124kcal/30g serving vs 154 kcal/30g block milk chocolate).

Sintering is used in the manufacture of Trencito Milki. In this product, sintered milk powder is coated with milk or white chocolate, and once in the mouth, the milk powder turns to liquid milk.

Aeration allows products to have a low weight in relation to volume, thereby reducing the calories in relation to volume, albeit not by weight. Nestlé has used aeration in the development and manufacturing of the Aero range of chocolate confectionery in several countries. There are various ways of including bubbles in chocolate, but the science of bubble formation is still poorly understood. Therefore, one avenue for Nestlé research has been to better understand this process (Haedelt et al 2005). In collaboration with the University of Reading, UK, Nestlé researchers have compared the effect of using various combinations of carbon dioxide, nitrous oxide, nitrogen and argon on flavour and gas retention in chocolate. While cocoa flavour was perceived as more intense in chocolate made with nitrogen and argon, bubble size and gas retention was better when carbon dioxide and nitrous oxide were used (Haedelt et al 2007).

In addition, the nutritional profile of chocolate can be improved – for example, by using less fat or sugar, or adding ingredients with positive health benefits. One example is the Milky Bar with added calcium, which is available in India. Nestlé Research has shown that consuming high-calcium chocolate (98-101g/day of chocolate that is 0.9 per cent w/w calcium for 2 weeks) has a measurable effect in reducing fat absorption, and lowering LDL-cholesterol (Shahkhalili et al 2001).

Communicating the benefits

When it comes to communication, Nestlé ensures that science-based facts are made in a rational and informative way. Nestlé Research has a role in providing science-based information about the potential health benefits of chocolate. For example, Nestle scientists have just published a detailed review of the last 10 years of research relating to the effect of cocoa on health (Cooper et al, 2008).

This review article focuses on the potential cardiovascular benefits of cocoa polyphenols. Interest in the antioxidant properties of cocoa polyphenols began in 1996 with the publication of a letter in the medical journal “Lancet”, reporting an antioxidant effect in vitro. Since then there have been approximately 30 human trials, mainly in healthy volunteers, testing the heart health-related benefits of cocoa or chocolate. Most studies have shown a measurable improvement of at least one cardiovascular parameter, such as blood pressure or blood antioxidant status.

Polyphenols are found in the cocoa liquor, and we have found that they are positively correlated with astringency and bitterness (Luna et al, 2002). They tend to be higher in dark chocolate than in milk chocolate, but this is not always the case since polyphenols can be destroyed by the manufacturing process (Cooper et al, 2007). It is not possible to reliably recommend an effective dose of polyphenols, cocoa or chocolate needed for cardiovascular health benefits. This is partly because the heterogeneity of the studies make generalised conclusions difficult, and because the bioavailability of relevant polyphenols (the flavanols) is important in determining dose. However, it is clearly the bioavailable polyphenol content and not the amount of chocolate which is relevant for health.

Moreover, the benefits are likely to be more relevant in people with impaired nutritional status (e.g. chronic antioxidant deficiency) or increased risk of cardiovascular disease, than in healthy individuals. Chocolate is a pleasurable way of obtaining polyphenols. However, the high energy density of chocolate means that the quantity consumed should be controlled.

By having a rigorous understanding of the health benefits and issues around chocolate, Nestlé is able to act responsibly in its communication about chocolate to consumers. The company uses the label to inform consumers, not just about the nutrient profile of chocolate products but also to provide information about the role of chocolate in a healthy balanced diet, including recommended portion size.

Premium and Luxury chocolate

Nestlé research and development for chocolate confectionery takes place mainly in our Product Technology Centre in York, UK. However, in order to strengthen its research and development capability in chocolate, Nestlé will open a new Centre of Chocolate Excellence at its factory at Broc in Switzerand, next year.

Premium and Luxury chocolate products, such as those under the Cailler brand, are at one end of the spectrum of chocolate products that meet emotional needs. The new Centre at Broc, which will open during the first half of 2009, will specifically address this line of products as well as the science of cocoa.

It will provide patisserier and confiseur expertise, as well as expertise in design and packaging. This in-house expertise will be enriched through an open innovation approach. Nestlé embraces collaboration and partnerships with external experts and organisations because, with the exponential growth in scientific knowledge, no single company can expect to have all the scientific and technical expertise that it needs in-house. This new capability in the Premium and Luxury end of the market will be further supported by Nestlé’s existing chocolate R&D competencies in the mainstream sector.

In conclusion, Nestlé has a long term commitment to research and development in chocolate, not only in chocolate processing, but also in the areas of consumer health and wellness. We are building on a strong innovation heritage, and will continue to bring chocolate innovations to consumers in the years ahead.

References

Afoakwa EO, Paterson A and Fowler M (2007) Factors influencing rheological and textural qualities in chocolate – a review. Trends in Food Science and Technology 18: 290-298.

Beckett ST (1999) Traditional Chocolate Making. Chapter 1 in “Industrial Chocolate Manufacture and Use” Ed Beckett ST, Oxford Blackwell Science.

Beckett ST (2001) Milling, mixing and tempering – an engineering view of chocolate. J Process Mechanical Engineering. 215:1-8.

Cooper KA, Campos-Giménez E, Jiménez Alvarez D, Nagy K, Donovan JL,

Williamson G. (2007) Rapid reversed phase ultra-performance liquid chromatography analysis of the major cocoa polyphenols and inter-relationships of their concentrations in chocolate. J Agric Food Chem. 55:2841-7.

Cooper KA, Donovan JL, Waterhouse AL and Williamson G (2008) Cocoa and heath: a decade of research. B j Nutr 99: 1-11.

European Union Directive 2000736/EC (2000) Directive 2000736/EC of the European parliament and of the council of 23 June 2000 relating to cocoa and chocolate products intended for human consumption. Off J commission Eur Communities L197:19-25.

Haedelt J, Pyle DL, Beckett ST, and Niranjan K (2005) Vacuum-induced bubble formation in liquid-tempered chocolate. J Food Sci 70: E159-E164.

Haedelt J, Beckett ST, Niranjan K. (2007) Bubble-included chocolate: relating structure with sensory response. J Food Sci. 72:E138-42.

Jolly MS, Blackburn S and Beckett ST Energy reduction during chocolate conching using a reciprocating multihole extruder Journal of Food Engineering 59 (2003) 137–142.

Lee s, Heuberger M, Rousset P and Spencer ND (2002) Chocolate at a sliding interface. F Food Sci 67: 2712-2717.

Luna F, Crouzillat D, Cirou L, Bucheli P. (2002) Chemical composition and flavour of ecuadorian cocoa liquor. J Agric Food Chem. 50:3527-32.

Nzabonimpa R and Apaicio A (1995) Determination of shell-in-cocoa nibs and nibs-in-shell by near infrared spectroscopy. pp277-281 in “Leaping ahead with near infrared spectroscopy” Ed Batten GD. Publ NIR Spectroscopy Group, Royal Australian Chemical Institute, North Melbourne, 1995, Australia.

Shahkhalili Y, Murset C, Meirim I, Duruz E, Guinchard S, Cavadini C, Acheson K. (2001) Calcium supplementation of chocolate: effect on cocoa butter digestibility and blood lipids in humans. Am J Clin Nutr.73:246-52.

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