Thomas Eidenberger PhD, Jack (Jingang) Shi
Abstract: This article introduced a widely neglected factor by beverage manufacturers-- Freshness. It explained in detail the definition, importance, influential factors of Freshness, how to evaluate Freshness and the methods to restore or improve Freshness in fruit-flavored beverages. The control experiment clarified that the perception of Freshness is a multi-sensory decision process and can be improved by adding specific taste modulators (flavors), and thereby increasing the consumer liking of fruit-flavored beverages.
Key words: Freshness, fruit-flavored beverages, sensory attributes, flavor, mouthfeel, taste modulators, consumer liking
The success of non-alcoholic beverages on the market depends on a variety of factors. Although sensory quality (flavor) is a central factor, manufacturers tend to follow simple concepts to evaluate sensory quality: (1) Design of packaging, (2) Color & Appearance, (3) Smell & Taste, (4) Comparison with competitors.
Common sensory properties ascribed to beverages by consumers are "fresh" and "refreshing". Not surprisingly the Health and Wellness Survey conducted in 2015 in 60 countries and involving 30.000 consumers, revealed that the most desirable food attribute is Freshness (Nielsen Global Health and Wellness Survey (2015) http://www.nielsen.com/us/).
Manufacturers neglect widely the importance of Freshness as sensory property of finished goods. It might be speculated that from the manufacturer's point of view, Freshness is introduced in products with the raw materials and by manufacturing conditions. It should be emphasized that beverages are perceived as fresh by consumers who are not aware of raw materials or manufacturing conditions.
The non-alcoholic beverage market is estimated to be about 1.000 billion US $. Major trends in this segment are the consumer desire for beverages promoting health and well-being. Sugar reduction, functional ingredients, "all-natural" and no added food additives are important to satisfy the desire for health, green/organic/sustainability and creating new experiences to satisfy the desire for well-being. Beverages following these trends are seldom rated top in Freshness.
To overcome this discrepancy between the major trends in the beverage industry and products rated top, Freshness has become a challenging task. Consequently, many new beverages on the market flop and disappear quickly from the shelves or become niche products for every selected consumer group. In our experience, neglecting the consumer-driven expectation of Freshness is the main reason for failing success.
Perception of Freshness is for beverages the most important sensory attribute to trigger high consumer liking and a buying decision (Roque J, Auvray M, Lafraire J. Understanding Freshness Perception from the Cognitive Mechanisms of Flavor: The Case of Beverages. Frontiers in Psychology (2018) 8, Article 2360).
1. How Freshness can be perceived
The "Oxford Languages and Google" provides a series of definitions and examples for the term Freshness (anguages.oup.com/google-dictionary-en/). From the various definitions provided it is obvious that Freshness is used in a multitude of meanings. Although only few of the meanings are relevant for beverages, other meanings may be transported by marketing and advertisement activities.
Freshness can be triggered on a semantic and symbolic level (i.e. presenting orange juice under an orange tree, freshly cut apple on a juice package, presenting a beverage bottle within a group of young and healthy people celebrating, or presenting youngsters sipping a bottle at the beach at sundown with strong wind) (Editorial. Psychology of perception:sensory evaluation and context. Theory and applications Revue européenne de psychologie appliquée 56 (2006) 209–211, Roque J, Auvray M, Lafraire J. Understanding Freshness Perception from the Cognitive Mechanisms of Flavor: The Case of Beverages. Front Psychol. 2018;8:2360. Published 2018 Jan 11. doi:10.3389/fpsyg.2017.02360).
Freshness can be triggered on a perceptual level and is an important part of the sensory characteristics of a product (smell, taste, mouth feel, cognitive mechanisms, and psychophysiological factors).
Semantic and perceptual information is processed concomitantly, inter-connected, and each other influencing. The processing involves a continuous context-based alignment with information stored in our memory (Breslin PAS, An Evolutionary Perspective on Food and Human Taste, Current Biology, Volume 23, Issue 9, 2013, Pages R409-R418). At the end of the processing stands a decision on whether or not Freshness is perceived.
Table 1 provides a summary of the timed sequence of sensations when tasting a beverage.
The first sensations are the color, the appearance (clear, cloudy, fizzy), and the temperature (ice in the glass, ice-coated bottle). These alone can already trigger a sensory decision (DLG Expert report 3/2017. Colours and their influences on sensory perception of products. http://www.evaderndorfer.at/pdf/DLG_3_2017_Expertenwissen_Sensorik_Farbe_englisch.pdf; Lawless H.T., Heymann H. (1999) Color and Appearance. In: Sensory Evaluation of Food. Food science text series. Springer, Boston, MA. https://doi.org/10.1007/978-1-4419-7452-5_12; A.G. de Bouillé, C.J.M. Beeren, 7 - Sensory Evaluation Methods for Food and Beverage Shelf Life Assessment∗,
Editor(s): Persis Subramaniam, In Woodhead Publishing Series in Food Science, Technology and Nutrition, The Stability and Shelf Life of Food (Second Edition), Woodhead Publishing, 2016, Pages 199-228, ISBN 9780081004357). In the case of unblinded tasting (i.e branded can) our brain may also trigger a decision solely on basis of the brand, the design of the can/bottle or the prize on the shelves.
The second set of sensations is related to the smell of a product, more precisely, ortho-nasal sensations experienced while breathing in. The smell (in the case of pleasantness "aroma") is a very important decision-making part of sensations as it determines whether we ingest a beverage or not (Purves D, Augustine GJ, Fitzpatrick D, et al., eds. (2001), "The Organization of the Olfactory System", Neuroscience (2nd ed.), Sunderland, MA: Sinauer Associates, retrieved 7 August 2016; Buck, L.2004 Olfactory receptors and odor coding in mammals. Nutr. Rev.62(11), S184 – S188). Interestingly, the recognition of a smell in our brain is more important than its pleasantness (i.e. the smell of tonic water is far from pleasant but quickly recognized).
When ingesting a beverage, contact with the tongue, the palate, and the cheek's mucosa create a variety of sensations that bombard our brain (Kikut-Ligaj D. et al. How taste works: Cells, Receptors and Gustaory perception. Cell Molec Biol Letter. 2015). Constant breathing while the beverage stays in the mouth, prompts retro-nasal sensations during breathing-out. Retro-nasal sensations affect the overall smell but also taste perception (Blankenship ML, Grigorova M, Katz DB, Maier JX. Retronasal Odor Perception Requires Taste Cortex, but Orthonasal Does Not. Curr Biol. 2019;29(1):62-69.e3. doi:10.1016/j.cub.2018.11.011; Rozin P. "Taste-smell confusions" and the duality of the olfactory sense. Perception &Psychophysics 1982,31 (4),397•401; Czarnecki L, Fontanini A. Gustation and Olfaction: The Importance of Place and Time. Current Biology 29, R16–R37, January 7, 2019). Evolutionary, the ortho- and retro-nasal "detection-system" is one of the most well-preserved systems and functions anatomically very similar to Dinosaurs and humans. The explanation is that ortho- and retro-nasal sensations are extremely important to prevent swallowing harmful food. While ortho-nasal sensations are acting as the first barrier preventing ingestion, retro-nasal sensations act as the last barrier preventing swallowing (Wilkes FJ, Laing D G., Hutchinson I, Jinks AL, Monteleone E. Temporal processing of olfactory stimuli during retronasal perception. Behavioural Brain Research 200 (2009) 68–75).
Swallowing of a beverage triggers anatomically the retro-nasal cavity which then is flooded with volatiles by breathing out immediately after swallowing (Steele CM, Miller AJ. Sensory input pathways and mechanisms in swallowing: a review. Dysphagia. 2010;25(4):323-333. doi:10.1007/s00455-010-9301-5).
In the last step, flavor receptors in the throat induce after-taste sensations.
2. Freshness is a multi-sensory decision
From a sensory point of view, perception of Freshness is a multi-sensory decision process (de Araujo IE, Simon SA. The gustatory cortex and multisensory integration. Int J Obes (Lond). 2009;33 Suppl 2(Suppl 2):S34-S43; Spence C. Multisensory Flavor Perception, Cell, Volume 161, Issue 1, 2015, Pages 24-35). Freshness cannot be perceived by single taste receptors nor is it represented by a single stimulus of somatosensory neurons.
The Freshness decision is based on olfactory (smell) and gustatory (taste) signals sent via chemoreceptors (receptor cells), somatosensory signals sent by mechanoreceptors (mechanical stimuli), and nociceptors (pain and temperature stimuli). Although different stimuli are recognized by different cells/neurons and the information is sent to the brain via different nervous pathways, the brain coordinates all the information concomitantly and aligns it with previous experience to make a decision (Shepherd GM. Smell images and the flavour system in the human brain. Nature, Vol 444, Nov 2006).
It is important to understand that perception of Freshness cannot be created de-novo by sensations. Freshness is perceived as a consequence of associative stimuli processing that relates to people’s previously experienced and memorized sensations and their meaning to us (D. Labbe, E. Almiron-Roig, J. Hudry, P. Leathwood, H.N.J. Schifferstein, N. Martin, Sensory basis of refreshing perception: Role of psychophysiological factors and food experience, Physiology & Behavior, Volume 98, Issues 1–2, 2009, Pages 1-9).
Freshness perception is mandatory to generate a refreshing feeling that is associated positively in the memory with Freshness. Fresh fruits are a good model to comprehend the perceived Freshness and the refreshing feeling (i.e. apple, orange). Freshness is not necessarily associated with a refreshing (i.e fresh bread, fresh fish) but in the case of beverages, especially fruit-based ones, a refreshing feeling is in most cases the ultimate target to achieve. A refreshing feeling is connected to the positive experiences of alleviating unpleasant symptoms in the mouth and throat (dry mouth, thirst) as a consequence of feeling hot, from exercise, or mental fatigue.
The Freshness decision depends on the combination of sensory signals and their fit with our acquired perception of Freshness. The more clearly and the easily recognizable a set of signals appear the quicker and easier our brain can decide on favor of Freshness perception. Ambiguity in a set of signals prevents a quick decision-making process. A set of unclear and/or unrecognized sensory signals triggers uncertainty in our brain. This uncertainty is either interpreted as "not recognizable" or yields a decision telling us "similar to …with following defects". Both are decisions against Freshness.
Quick and early recognition of a flavor is not only of major importance for the Freshness decision. Our brain tends to stop further considerations once a decision is made (an evolutionary useful feature as thinking costs a lot of energy). In other words, once a Freshness decision is made, sensory attributes will stop making failure responses or defect analysis much less probable than in cases where it took a long time to recognize a flavor.
Freshness perception is an important contributor to "consumer hedonic preference". A complicated and long-lasting sensory decision-making process to recognize a flavor triggers failure search and defect analysis (lower overall quality rating).
3. Freshness in beverages
The aroma (smell) is the first sensory attribute contributing to Freshness. The Freshness of fruit-based beverages is assessed by the perceived closeness of the smell to the perception of the original, unprocessed fruit. The closer the smell resembles the fresh fruit, the quicker our brain assigns it to the corresponding fresh fruit. Complex aromas in mixed fruit beverages can easily create ambiguity and disturb the decision-making process. In such cases, it should be considered to formulate the beverage with a quickly recognizable lead (dominant) aroma. Table 2 shows the effects when comparing a commercial "mixed red fruits juice" without and with added bilberry flavor to create a dominant aroma.
In an ideal scenario, the smell triggers the decision-making process and a fresh expectation is already created. It has to be emphasized that such an expectation needs confirmation by taste.
Taste is a major player in the Freshness perception as it can confirm expected Freshness or direct the brain by additional sensory attributes to the favored decision. Taste is part of the overall sensations in the mouth which include also the temperature, viscosity, sparkling properties, and mechanical stimuli (shredded fruits).
Freshness is the consequence of a flavor perception (processed sensory attributes) if all sensory signals point in a balanced, coordinated, and unambiguous way to the same stored image in our brain associated with Freshness.
A refreshing feeling results from a Freshness decision together with a mouthfeel that is described as mouth-watering (Fischer, U., Boulton, RB., and Noble, A.C. (1994). Physiological factors contributing to the variability of sensory assessments: relationship between salivary flow rate and temporal perception of gustatory stimuli. Food Qual Pref 5 :55-64). Mouth-watering is triggered by a balanced sweet/sour balance, a harmonic embedded taste signaling Freshness, and the absence of mouth-coating and lingering (fresh milk would be an example where Freshness is perceived by smell and taste, but due to the lack of sweet/sour balance and mouth coating properties milk is usually not associated with refreshing).
4 . Creating Freshness during flavor perception
Aroma and taste are mainly responsible for perceived Freshness. Mouth feel contributes to the Freshness perception and is of utmost importance for a refreshing feeling.
Recently, to connect the impact of mouth feel on the overall flavor perception, a model for universal flavor factors has been used (Klosse PR. Flavor Classification, Another Paradigm. Towards a universal flavor model, (2017), DOI: 10.13140/RG.2.2.35017.65126), see Table 3.
In this model, beverages are classified according to the mouth feel (contracting, coating, drying) and flavor intensity/complexity (low, high). Contracting mouth feel is experienced as tactile "tingling" or "stinging" impression which is perceived as a refreshing feeling. Acidity, saltiness, and coldness (ice cubes) trigger a contracting mouth feel in the mouth. Refreshing is closely associated with a dominant mouth contracting and a low flavor intensity/complexity (equivalent to quick recognition).
Lemon beverages follow this categorization and are a prototype model for Freshness/refreshing feeling. Pear juice can be perceived as fresh but is seldom refreshing. Low-quality orange juice (pressing whole oranges at elevated temperature) is not perceived as fresh due to off-tastes contributed by skin and albedo (white skin) ingredients present in the juice.
5. Why beverages lack freshness
Lack of Freshness can be caused by defects in a product. This case is excluded from further considerations below.
Frequently beverages lack Freshness due to a mismatch of aroma and taste. Any mismatch creates ambiguity and prevents an early and clear flavor recognition which is important for Freshness perception. Aroma creates an expectation and if the expectation is not confirmed by taste, ambiguity in the processing of sensory signal occurs.
Crude aroma and taste mismatches are nowadays seldom seen due to better flavors on the market and improved technology.
However, even subtle mismatches cause ambiguity and delay in recognition but are much more difficult to correct. Especially improvement of taste is challenging due to the multitude of different sensations and their inter-dependence.
Following list shows frequent causes for subtle taste deficiencies:
Off-Notes (artificial, metallic, bitter, herbal)
Impaired sweet/sour balance
Too sweet or too sour
Time to onset and to peak intensity unbalanced
Mouth-feeling
Unexpectedly mouth-coating (thickener, high viscosity, aged or over-ripe fruits)
Weak mouth-watering (weak taste, lack of sourness)
Empty/void (lack of sugar)
Sweetness profile (especially sugar reduced/sugar free products)
Onset of sweetness too slow
Long lasting peak sweetness
Lingering sweetness
Impaired Time/Intensity sequence
Flavor, sweetness and acidity time/intensity curves are not congruent (not fitting to
the expected fruit flavor)
6. How freshness perception can be improved
EPC Natural Products has developed a range of products to improve the flavor perception and guide our brain to a Freshness decision.
One example is to add Zestaroma™ 200LN (200 ppm) to lemon juice with 5 % sugar. A comparative sensory evaluation showed that the addition of Zestaroma™ 200LN accelerates the time to peak flavor intensity, with a quicker recognition of the flavor. The Freshness perceived is rated substantially higher (4 against 2 on a five-point scale) in the sample with Zestaroma™ 200LN added (see Figure 1).
Figure 2 shows a sensory comparison for a commercial apple juice (7 % sugar) with the addition of Zestaroma™ 200LN (200 ppm). The effect observed relates to an increase in the timed congruence of sweetness, acidity and flavor. The overall effect of the addition of Zestaroma™ 200LN is described as more balanced flavor, more matching natural (apple) and as better Freshness perception.
Figure 3 shows a sensory comparison of orange juice samples prepared with a 50 % sugar reduction by adding Aspartame/Acesulfame-K without or with Zestaroma™ 200LN (200 ppm). In these samples, Zestaroma™ 200LN can almost reverse the changed perception of acidity and sweetness introduced by artificial high-intensity sweeteners.
Figure 4 shows a comparative sensory evaluation of a sugar-free carbonated orange/mango beverage with or without Zestaroma™ 200LN. In this example, the Time Dominance Sensations for 3 attributes (acidity, sweetness and adequate mouth feel) was recorded. As seen addition of Zestaroma™ 200LN corrected the inadequate mouth feel and the inadequate time dominance of acidity/sweetness to yield a flavor perception rated as much more sugar-like sweetness, improved sweet/acidic balance and improved mouth feel.
These examples show convincingly that the product range of Zestaroma™ is able to correct the flavor perception in various aspects to yield increased Freshness perception and ultimately a refreshing feeling.
7. Conclusions
The market for non-alcoholic beverages exceeds the 1.000 billion US $ margin. The success in this market depends on the Freshness and Refreshing feeling associated with a beverage by consumers. Perception of Freshness for beverages is the most important sensory attribute to trigger high consumer liking and a buying decision.
From a sensory point of view Freshness is a multi-sensory decision mainly based on smell and taste signals processed in our brain. Quick and easy recognition of a flavor is the basis for Freshness perception. Complicated flavor with ambiguous signals sent to the brain prevents quick recognition and finally a Freshness perception.
Many products on the market suffer from more or less subtle deficiencies in smell and taste. Usually smell creates an expectation which needs confirmation by taste. Any mismatch between smell and taste disturbs the required quick recognition required for Freshness and refreshing perception,
The product range of Zestaroma™ corrects various aspects of smell and taste deficiencies as well as mismatches yielding improved Freshness perception and ultimately a refreshing feeling.
References
—————
[1] Nielsen Global Health and Wellness Survey (2015) http://www.nielsen.com/us/ (accessed October 22nd 2020)
[2] Roque J, Auvray M, Lafraire J. Understanding Freshness Perception from the Cognitive Mechanisms of Flavor: The Case of Beverages. Frontiers in Psychology (2018) 8, Article 2360
[3] Editorial. Psychology of perception:sensory evaluation and context. Theory and applications Revue européenne de psychologie appliquée 56 (2006) 209–211
[4] Roque J, Auvray M, Lafraire J. Understanding Freshness Perception from the Cognitive Mechanisms of Flavor: The Case of Beverages. Front Psychol. 2018;8:2360. Published 2018 Jan 11. doi:10.3389/fpsyg.2017.02360
[5] Blankenship ML, Grigorova M, Katz DB, Maier JX. Retronasal Odor Perception Requires Taste Cortex, but Orthonasal Does Not. Curr Biol. 2019;29(1):62-69.e3. doi:10.1016/j.cub.2018.11.011
[6] Rozin P. "Taste-smell confusions" and the duality of the olfactory sense. Perception &Psychophysics 1982,31 (4),397•401
[7] Czarnecki L, Fontanini A. Gustation and Olfaction: The Importance of Place and Time. Current Biology 29, R16–R37, January 7, 2019
[8] Wilkes FJ, Laing D G., Hutchinson I, Jinks AL, Monteleone E. Temporal processing of olfactory stimuli during retronasal perception. Behavioural Brain Research 200 (2009) 68–75
[9] Steele CM, Miller AJ. Sensory input pathways and mechanisms in swallowing: a review. Dysphagia. 2010;25(4):323-333. doi:10.1007/s00455-010-9301-5
[10] de Araujo IE, Simon SA. The gustatory cortex and multisensory integration. Int J Obes (Lond). 2009;33 Suppl 2(Suppl 2):S34-S43
[11] Spence C. Multisensory Flavor Perception, Cell, Volume 161, Issue 1, 2015, Pages 24-35
[12] Breslin PAS, An Evolutionary Perspective on Food and Human Taste, Current Biology, Volume 23, Issue 9, 2013, Pages R409-R418
[13] DLG Expert report 3/2017. Colours and their influences on sensory perception of products. http://www.evaderndorfer.at/pdf/DLG_3_2017_Expertenwissen_Sensorik_Farbe_englisch.pdf
[14] Lawless H.T., Heymann H. (1999) Color and Appearance. In: Sensory Evaluation of Food. Food science text series. Springer, Boston, MA. https://doi.org/10.1007/978-1-4419-7452-5_12
[15] A.G. de Bouillé, C.J.M. Beeren, 7 - Sensory Evaluation Methods for Food and Beverage Shelf Life Assessment∗, Editor(s): Persis Subramaniam, In Woodhead Publishing Series in Food Science, Technology and Nutrition, The Stability and Shelf Life of Food (Second Edition), Woodhead Publishing, 2016, Pages 199-228, ISBN 9780081004357
[16] Purves D, Augustine GJ, Fitzpatrick D, et al., eds. (2001), "The Organization of the Olfactory System", Neuroscience (2nd ed.), Sunderland, MA: Sinauer Associates, retrieved 7 August 2016
[17] Buck, L.2004 Olfactory receptors and odor coding in mammals. Nutr. Rev.62(11), S184 – S188
Kikut-Ligaj D. et al. How taste works: Cells, Receptors and Gustaory perception. Cell Molec Biol Letter. 2015
[18] Shepherd GM. Smell images and the flavour system in the human brain. Nature, Vol 444, Nov 2006
[19] D. Labbe, E. Almiron-Roig, J. Hudry, P. Leathwood, H.N.J. Schifferstein, N. Martin, Sensory basis of refreshing perception: Role of psychophysiological factors and food experience, Physiology & Behavior, Volume 98, Issues 1–2, 2009, Pages 1-9
[20] Fischer, U., Boulton, RB., and Noble, A.C. (1994). Physiological factors contributing to the variability of sensory assessments: relationship between salivary flow rate and temporal perception of gustatory stimuli. Food Qual Pref 5 :55-64
[21] Klosse PR. Flavor Classification, Another Paradigm. Towards a universal flavor model, (2017), DOI: 10.13140/RG.2.2.35017.65126
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