Emerging Research in Aromas & Sweetness Enhancement

August 24, 2017–The following presentation is from the “2016 Sweetener Systems Conference Summary,” sponsored by Orochem. All presentations and/or adapted versions made available by the speakers are posted on Global Food Forums Inc’s store page. Please consider attending our 2017 Sweetener Systems Conference, November 7th, at the Westin Hotel, Lombard, Ill., USA. 

Additions of tomato and strawberry volatiles associated with sweetness to their respective fruits to 2% sucrose solutions incrementally increased the perceived sweetness of the sucrose solutions by as much as 75%. [For larger PDF version of chart, click on image.]

The presentation by Thomas Colquhoun, Ph.D., Plant Biologist at the University of Florida (Gainesville), built further on the concept of multi-modal sweetness perceptions developed by previous speakers. The focus was on the potential role of volatiles and, perhaps also color and shape, on sweetness perception.

“I run a plant biotech lab that is affiliated with the UF/IFAS Plant Innovation Center, for which the overarching goal is to better people’s lives through better plant products,” explained Colquhoun. “We do this by enhancing the aesthetic appeal of plants; increasing flavor and nutritional value; and delivering plant products that consumers actually want.”

Colquhoun explained the process used: “The first step is to test and quantify consumer expectations and perceptions using methods referred to as ‘psychophysics.’ We try to understand what people’s perceptions are of plant products, from taste and flavor to emotion and perceived importance.”

Second, the germplasms of various plants are screened for biochemicals and physical attributes linked to specific, consumer-identified desirability traits. “We link molecular biology, biochemistry and psychophysics,” said Colquhoun. Finally, once the specific plant genes associated with desirable traits are identified, breeding programs are developed to imbed the desired characteristics into the targeted plants.

The laboratory’s first application of these methods identified that “sweetness” was the most desirable trait that consumers identified with strawberries. The next step was to
categorize all available strawberry germ plasms by their respective combinations of sugars, acids and volatiles (although, Colquhoun noted, geography and growing conditions can also affect these variables within specific cultivars). Sensory analysis, using the psychophysics process, was then used to identify the optimum combinations of these metabolites that consumers associated with sweetness.

“Going through this process, we stumbled upon the phenomenon of ‘volatile-enhanced taste,’” observed Colquhoun. “We identified volatiles that significantly contribute to
the perception of sweetness without the presence of sugar on the tongue.” This required the use of highly sophisticated and very expensive equipment, such as the laboratory’s triple-quad mass spectrophotometer, because when dealing with “human psychophysics data,” there is so much variation in the sensory data that it is necessary to obtain the highest

resolution available at the biochemical level. Even minute variations in biochemical data may be correlated to specific taste and flavor perceptions. In time, the scientists developed a  relational model that was sufficiently and consistently sensitive to be applicable to different fruits across different harvest conditions.

“When we applied a hierarchical cluster analysis to strawberries, tomatoes and blueberries, something very interesting popped out,” said Colquhoun. All three of these
fruits’ consumer profiles clustered out according to perceived sweetness; but, when clustered on the basis of their chemistry, they grouped out on the basis of their fruit identity. Thus, an important discrepancy was identified between the fruits’ basic chemical compositions and their perceived sweetness.

The question of “why?” necessitated building complex, multivariate models capable of associating specific and minute metabolite concentrations to specific sensory attributes.
The researchers found there were specific metabolites associated with “sweet” taste; and others associated with salty and bitter tastes, as well as “overall liking” and “overall fruit flavor” perceptions. Most compelling were the following two responses linked to sweetness:

1) The overall sweetness perceptions for blueberries were considerably lower than those for strawberries, at a fixed sugar content; i.e., it required a 2-3-fold higher sugar content in blueberries to match the perceived sweetness of strawberries. This result appears to support data, presented in an earlier presentation by Alex Woo, Ph.D., of W2O Food Innovation, indicating that red colors strongly evoke sweetness perceptions in foods and beverages.

2) Adding specific volatiles gleaned from strawberries and tomatoes to a 2% sucrose solution incrementally increased the sweetness perceptions of the sucrose solutions by 25-75%.

In conclusion, the roles of volatiles in modulating perceptions of sweetness are very real and substantial, as are the challenges of manipulating and measuring the presence of the same volatiles in the fruit. Thus, even tiny changes can offer enormous payoffs.

“Emerging Research in Aromas and Sweetness Enhancement,” Thomas Colquhoun, Assistant Professor, Plant Biotechnology, University of Florida, ucntcme1@ufl.edu


Posted on:August 24, 2017

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