By: Katharina Pletsch and Frithjof Raab *
The Main component of classic sugar confectionery products, like hard boiled or gummy candies of course, is sucrose. However, as candies are increasingly a target for sugar reduction exercises, polyols, such as isomalt, would then be the main ingredient. Flavor is then added to give the candy the desired taste. But in order to create a well-balanced, delicious product, one more ingredient is essential. For a rounded, optimized taste profile an organic acid is needed to counteract the sweetness. Traditionally citric acid has been the acidulant of choice in the sugar confectionery industry. But acids do not simply provide sourness. Depending on the type of acid and its individual taste characteristics, it will influence the whole taste profile of the final product. The interaction of flavor, sweetener and acid defines the flavor profile.
Acid/sweetness balance for a harmonious taste impression
Human beings are able to perceive five basic tastes: sweet, sour, salty, bitter and umami. In confectionery, sweet and sour play the most important role. Initially, confectionery products should impart sweetness. However, for a rounded taste impression an acidic component is needed, and it is crucial to achieve a good balance between these two basic ingredients. Citric acid is often used for acidification in sugar-based products. The combination works well, because the time-intensity curves for the two components are almost identical, i.e. the sweet and sour tastes reach their maximum almost simultaneously. Replacing sugar with high intensity sweeteners (HIS) usually results in a typically sweet aftertaste and off-note detection which outlasts the sourness of citric acid. Therefore a combination of citric acid and malic acid is often used to cover the persisting sweetness of HIS.
In combination these two acids display a synergy in sourness intensity and persistence resulting in a rebalanced acid/sweetness perception in HIS sweetened products. Figure 1 demonstrates the sourness intensity and persistence of citric acid and malic acid used as single acidulants, as compared with combinations of the two. Citric acid has slightly greater sourness intensity than malic acid but the sourness does not last as long. Both acids correspond quite well with the sweetness perception time associated with sugar, but the typical sweet aftertaste of HIS cannot be covered using either of these acids alone. However, in combination the two acids synergistically prolong the perception of sourness and therefore compensate the sweet aftertaste (indicated by the greenish background).
Figure 1 also shows the acidic taste profile of a 50/50 mixture of citric acid and lactic acid, which performs an even stronger synergistic effect.
In total the acidic taste intensity of the citric acid/lactic acid combination is slightly higher and the acidic taste is clearly prolonged compared to the combination containing malic acid. Hence the sweet aftertaste and other off-notes are better compensated. This combination therefore represents a feasible alternative to malic acid.
Both citric acid and lactic acid manufacturing processes are based on fermentation. This is a clear advantage when it comes to consumer desires for more natural ingredients. Malic acid, in contrast, is a synthetic product made from petrochemical raw materials. Citric acid and lactic acid are therefore clearly preferable.
Descriptive Sensory Study: Taste modulation in hard boiled candy
In the quest for a particular taste a broad range of different flavor types with many variations are available to confectionery manufacturers. It may take a long time until the perfect match is found, but often just a slight adjustment to the basic formula provides the desired finishing touch.
A descriptive sensory study was designed to demonstrate the effect of different acids and combinations thereof on overall taste in sugar confectionery products. An expert panel examined a test matrix representative of sugar-free candies in a conventional sensory profile (DIN ESN ISO 13299).
As test matrixes, 30 percent solutions of previously cooked and then dissolved sugar-free candies containing different acid combinations were chosen. Acid dosages had been 1.5 percent except for the combination of citric acid/ gluconic acid (50/50) with 2 percent. These were tested on two natural flavors especially suited for confectionery applications: strawberry (creamy, ripe, juicy) and orange (fresh, peely)
Eight trained panellists initially characterized the samples with relevant and objective sensory attributes (from the categories odor, basic taste, flavor and mouthfeel) and subsequently rated the perceived intensity of each descriptor on a 7-point-scale.
The results of this study provide reasonable evidence that changing the acidulants significantly influences the overall taste of strawberry-flavored hard boiled candies and thus gives every end product a distinctive character.
For example, compare the sensory profile of pure citric acid (CA 100) against its combinations with lactic acid (CALA 50/50) and the relatively mild gluconic acid (CAGA 50/50) (Figure 2): replacing half of the citric acid can either emphasise (lactic acid) or suppress (gluconic acid) the greenish-unripe tones of the strawberry flavor. While gluconic acid also reduces sourness and astringency, it maintains the jammy/cooked and ripe tone of citric acid alone. The addition of lactic acid emphasises green-unripe flavors by increasing sourness and astringency while reducing ripe and jammy/cooked flavors.
An example which indicates rather the opposite, namely the exchangeability of one acidulant with another, is shown in Figure 3. This figure is based on the results of the orange flavor evaluation and compares citric acid alone (CA 100) to the common combination of citric acid with malic acid (CAMA 50/50) or with lactic acid (CALA 50/50) already described above. The only significant differences found were for the highest acid perception. Overall the picture clearly indicates that the acid/sweetness profile of CALA 50/50 is equivalent to that of CAMA 50/50. Taking citric acid alone as baseline, the lactic acid combination is close to or even matches the malic acid combination. Both combinations influenced sour (increase) and sweet (decrease) taste in the same direction and to a comparable extent.
In order to get the most out of a sugar confectionery product, it is above all important to achieve a good balance between acidity and sweetness. The acids and sweeteners used therefore need to fit together in terms of persistence and intensity profile. The profile of citric acid matches perfectly to the sweetness of sugar. However, imbalances occur as soon as the sugar is replaced by other substances, e.g. high intensity sweeteners. Here, optimized acid combinations can help to cover lingering sweetness or even off-tastes.
Different acidulants can also influence the flavor characteristics of sugar confectionery beyond adjusting acidity and sweetness. The sensory profiling of a strawberry- or orange-flavored sugar-free hard boiled candy formulation demonstrates that different acid combinations modulate the original flavor in different directions. This knowledge provides some flexibility to product developers in emphasising specific flavor notes. Hence, it is possible to reduce the sweet impression while increasing the unripe notes of a certain flavor just by exchanging one acid component for another or by changing the ratio of an acid combination. Conversely, some acids can be exchanged for others with only a minor influence on the taste profile of the formulation. This can be advantageous in terms of cost savings or if more natural solutions are required.
Even if specific tests would be required to determine the flavor-modulating effect of different acids and their combinations on a case by case basis, this study provides a good guide as to how to use acids in a more sophisticated way and how to improve the overall taste of a sugar confectionery product with only small adjustments.