Flavoured chocolate bars can be broadly divided into 2 categories: Infusion (or flavouring) bars, and inclusion (or pieces) bars. There are some differences in how to evaluate these bars especially on the appearance and texture, however the general principles are similar.
One thing that you may be surprised is that the way we assess flavoured bars is not that different to filled chocolates. While the ratio of chocolate vs flavoured ingredients may be different, we would still look at similar aspects.
For inclusion bars, many chocolatiers would use a variety of colourful ingredients to make the bars look pretty - for example, any red fruit (e.g. strawberries, raspberries) pieces or powder would look stunning on a white chocolate bar. This can be more difficult with infusion bars, as the colour incorporated into the chocolate may not look so appealing. In any case, the chocolate should still have a nice touch to it. There should be a clean snap when you break into the bar - this can be more tricky with certain ingredients which may make the chocolate lose the snap (e.g. something with a high fat content).
Depending on the chocolate and ingredients used, the bar may have the aroma of the chocolate and/or the ingredients. This usually gives us the first clue on the quality of the bar and of the ingredients used.
One good way to understand this is to compare freshly-ground coffee versus instant coffee, or freshly-ground spice versus an old jar of spice. The freshly-ground ingredient will have a more vibrant aroma, while instant stuff (especially if it’s been opened for a while) would have a much duller smell.
The aroma can be a good indicator, especially on the defects. If the bar has a burnt smell or a rancid smell, it’s usually an indication that the chocolate used may not be of a good quality, or the ingredient used to flavour the bar has gone off.
The texture of the bars would be affected by the type of ingredients used, as well as the proportion of chocolate vs inclusion/infusion. While it’s nice to include a generous amount of nuts, if there’s not enough chocolate, then it would feel like eating a protein bar instead. Similarly if there’s so few nuts on a bar, then you would feel like you are eating just a plain chocolate bar when the piece you put in the mouth has got no nuts on it.
If you consider using soft inclusion pieces (e.g. candied fruit), you then have to consider whether the pieces would dry out and become hard after a few days especially if you place the pieces on top of the bar - this is a compromise between the appearance and the texture. Again the ratio between the chocolate and the pieces is important.
Another aspect relating to the texture is the mouthfeel, and this can be tricky when an ingredient is grounded to a powder form and incorporated into the chocolate. Depending on how fine the ground particles are, the chocolate may no longer be smooth and can affect the mouthfeel. For example, with coffee chocolate bars, some makers would dissolve instant coffee into the chocolate, which may be smooth but the flavour may not be so desirable; while some other makers may incorporate fresh ground coffee into the chocolate, which will have a better taste but the chocolate will have a gritty texture in the mouth. The best one we came across a few years ago was the coffee milk chocolate bar from Omnom when we visited their factory - they actually grinded the coffee beans with the cacao beans together, and the result was this smooth rich "cafe au lait" sensation.
The flavour of the inclusion or infusion should marry well with the flavour of the chocolate, and one should never overpower the other. This becomes important when it comes to the choices of chocolate used. For example, if a chocolate with a rather smokey flavour is used (such as one from Papua New Guinea or Indonesia), then using a smokey lapsang souchong tea may not be a good idea because it’ll be two different smokiness battling out with each other.
Also bear in mind that the flavour of the ingredient may develop over time and so if it appears too weak at the start, it may not be a bad idea as the flavour develops and intensifies when the chocolate melts. This is especially true for chilli – we have tried many chilli chocolates where the heat hits the tongue as soon as you put the chocolate in the mouth, and by the time you finish the chocolate, the taste bud was completely burnt out by the heat of the chilli and you cannot taste any chocolate whatsoever.
The finish should be on the chocolate, with perhaps a lingering pleasant taste of the inclusion or infusion to go with it. Again this is where the choice of chocolate becomes important – a bad quality chocolate would leave an unpleasant finish in the mouth; and if you try to mask it with an overpowering flavour, then the overall flavour would become unbalanced also.
To give you an example on some of these aspects, we'll use one of our products, Salmoran, as an example. This is not really a chocolate bar as such but it's a mixture of chocolate, crushed almonds, candied orange peel and sultana. The chocolate and almonds give a more crunchy texture, while the orange peel and sultana provide the contrasted soft texture. During the development process, we have tried various ratios of these ingredients - with too many pieces of soft fruit, we ended up with a very soft texture that is not associated with chocolate. We have opted for the Colombian 65% cacao dark chocolate, as the higher percentage did not work as well with these inclusion pieces in terms of the overall flavour profile. Some customers have asked if we do a milk chocolate version - we have tried it and the flavour balance is lost also.