Obesity is a problem that has been increasing in prevalence, even attaining newfound status as a disease in recent months. With this issue brought to the fore, many have developed greater health consciousness and a targeted focus on better nutrition, resulting in the demand for products with less sugar, salt, fat and calories, and preferably fortified with nutrients.
This has had a direct impact on beverages, which is one of the top few categories blamed for providing empty calories or sugar laden products, especially in the case of juices and carbonated soft drinks. As a result, manufacturers have introduced formulations with reduced sugar and recipes that use non-nutritive sweeteners (sweeteners with few or no calories) as replacements.
Nonetheless, there is only so much sugar that manufacturers can remove before taste is compromised. Most non-nutritive sweeteners (eg: aspartame, saccharin and stevia) come with an aftertaste that consumers find unpleasant. This proves as an impediment as taste is after all, the hallmark of commercialisation success. Fortunately, flavour is a multi-faceted component that mirrors the complexity of the human sensory system.
Depths Of Flavour
D. Sharon Pruitt, Layton, US
Contrary to what is believed, flavour is not confined solely to the five taste perceptions of sweet, sour, bitter, salty and umami. In fact, the different types of tastes are not segregated to specific areas of our tongue as commonly taught.
Studies have shown that the human tongue has receptors for tastes that include fat, calcium, water, metallic, and even carbonation. In the same vein, overall flavour perception is much more than just what our taste buds detect; it is a multi-sensory experience that combines taste, smell and sensations like irritation, texture or mouth feel, and thermal levels.
This makes smell as important as taste or sensation, which has often been overlooked in product development. In a time when developments in the two latter areas may be saturated, olfaction serves as a complementary solution to better formulate flavoured food products that fulfil specific nutritional recommendations and consumer expectations.
For instance, some studies have highlighted the effect of aroma release on enhancing satiety and decreasing food intake. Foods contain volatile chemicals that activate our olfactory receptors, which happens when we actively sniff food (orthonasal olfaction), or are released when we chew our food, where the aroma then travels through the back of the throat (retronasal olfaction).
Flavour perception, depending on the activation route, is influenced by the dynamic release patterns of volatile compounds during chewing, as well as the signals that tastebuds on our tongue are sending to the brain. Known as the taste capture of odour, the brain consolidates sensory information from multiple sources before transferring it to our mouth.
It is through this unitary concept of flavour that abilities like masking an unpleasant flavour or making something taste sweeter than it really is are possible.
In light of the recent studies suggesting that sweeteners may be exposing consumers to the very same risks they are trying to avoid (eg: type 2 diabetes, cardiovascular disease, weight gain), aromatics could possibly be the reprieve that the beverage industry is looking for. Volatiles could be used to enhance the taste and perception of sweetness while allowing manufacturers to ease up on added sugar or sweeteners.
This works especially well in pairings that are appropriate and congruent in nature. Some tested models that successfully enhanced sweetness perception includes the addition of vanilla flavouring to milk, as well as the common pairing of the smell of strawberries to whipped cream.
Apart from increasing sweetness, adding sucrose to juices can also decrease sourness and bitterness while enhancing fruit odours. Another potential method of prolonging aroma delivery is the inclusion of fruit bits, which not only increase exposure time but also modifies oral processing.
However, odours can also be used to reduce taste intensity in cases where the pairings are incongruent. For instance, the smell of caramel has successfully decreased the intensity of sourness. Flavour technology can also be used to mask undesirable flavour notes like bitterness in sweeteners, a common issue today.
More importantly, aromatics can be used to increase the efficiency of sweet taste receptors, which allows developers to enhance the impression of sweetness without having to increase the quantity of nutritive or non-nutritive sweeteners.
David Pacey, Leeds, UK
A huge impediment to aroma delivery is its susceptibility to diffusion and degradation, either through chemical reactions with other ingredients or through oxidation after exposure to air. In certain cases, degradation could lead to off notes in the end product.
Consequently, efforts have been focused on building sophisticated encapsulation systems, such as those that can deliver controlled releases of sweet smelling aromas to boost sweetness. In terms of fortified beverages, such systems also protect nutrients like vitamins, minerals and polyunsaturated fatty acids from degradation due to oxidation.
Drawing inspiration from shelf life enhancement of beverages, coacervation techniques are promising in controlling aroma releases as well. Coacervates are tiny lipid molecules (eg: fat, oil) that are held together by hydrophobic forces and surrounded by a tight skin of water molecules.
This method is particularly useful with viscous, semi-solid products, where in one example, limonene was successfully encapsulated. However, flavour release is dependent on capsule sizes and the cross linkages across wall materials.
Another way of incorporating flavour into beverages is through oil encapsulation in gel particles, which could be made out of gelatine, agar or starch. Depending on the medium, the flavours are then released through thermal triggers (gelatine), interactions with digestive enzymes (starch), or chewing (agar), resulting in a burst of aroma.
Should encapsulation be insufficient, masking techniques can be used to account for undesired flavours that may occur along a product’s shelf life. Depending on the flavours inherent in the product, selected volatile compounds can be added to block access to an olfactory receptor that is responsible for a specific odour that is undesired.
Because finding the right compounds to mask a specific set of odours are traditionally time consuming, some researchers have devised an olfactoscan screening method that makes use of an olfactometer and a gas chromatography with odour port to speed things up.
A novel way of using encapsulation for aroma delivery is incorporating it into packaging, which bypasses the challenges of chemical reactions or atmospheric degradations. US company ScentSational has developed packaging applications where specially engineered, FDA approved food grade flavours are added to the plastic packaging at the time of manufacturing.
This results in a stable delivery of volatile compounds, which may be released at point of purchase, package opening, product preparation or consumption. Suitable for both flexible and rigid packaging, standard barrier layers are used to keep the flavours sealed within the package until it is opened.
Effervescent methods are extremely useful for instant drinks like coffee, which are heavily dependent on aroma delivery for the perception of product quality. Particularly for processed coffee, a lot of flavour is degraded during processing due to its delicate and unstable nature, leaving behind unpleasant notes that are unlike coffee.
To prevent this from happening and to prolong the intensity and duration of aromas in headspace, researchers from the University of Nottingham have devised an alternative to using conventional agents like sodium hydrogen carbonate or citric acid to release volatile compounds.
In their method, spray dried coffee powder is heated beyond its transition temperature and put under elevated pressure until it becomes plasticised and permeable, which allows internalised gas to be incorporated into the powder. Upon adding water to the instant powder, gas will be released either when it rises to the surface or when it forms the crema (the top layer of froth covering the coffee). Compared to using effervescent agents, this method of trapping pressurised gas has much faster and intense results.
Meanwhile in beverages like beer, champagne and carbonated soft drinks, effervescent techniques are used to increase in-vivo aroma delivery. Carbonation in beer increases aroma delivery after consumption, while in champagne, the formation of gas bubbles significantly enhances the release of aromas.
SteFou!, Toronto, Canada
Vox Efx, Baltimore, US
In other studies, it has been found that the content of carbohydrates and lipids in instant beverages has a direct impact of aroma delivery. Adding fructose increases the viscosity of the solution as well as its solubility, enhancing the delivery of volatiles. As a result, beverage manufacturers must be mindful that reformulations involving fat reduction or nutritional enhancement could affect not just functionality, but also attributes like aroma delivery.
With its technical limitations, the use of volatiles is not a one-fit solution for all industries. However, its potential in helping beverage manufacturers achieve their fat and sugar reduction goals is simply too big to ignore. Not to mention, volatiles have an unimaginable impact on sensory evaluation and the overall development of health-oriented products. Despite its challenges, continual developments technologies like encapsulation and effervescent methods are successfully bringing the volatile concept much closer to reality, and with it, the sweet dream of tasty, healthy, sugar-free drinks.