Spectrophotometric Analysis of Wine Colour Can Enhance Sensory Perception

Colour is so essential to our experience of wines that it can fundamentally alter our sensory perceptions. Image Source: Pexels user stock.tookapic.com

I don’t like red wine. I have unshakeable faith that there is a difference between how red wines taste and smell and I will pass them over in favor of a white wine regardless of type or origin. I also know that this has no basis in reality.

A 2001 psychological study led by Frédéric Brochet from the University of Bordeaux invited a panel of 54 wine experts to evaluate the flavor and scent of one white wine and one red. The experts responded by describing white wines in terms commonly used when speaking about white wines while the red wines were described in typical red wine terms, with phrases like “crushed red fruit” and “jammy.” The problem is that the wines were, in fact, identical white wines, one of which had been dyed with scentless artificial food coloring. The flavor and olfactory differences reported were not qualities of the wines themselves, but ascribed based on pre-existing associations with visual information. Rather than describing the wines, the experts were describing their assumptions about wine colour.1 If people who have devoted their careers to the categorization, description, and experience of wines can’t tell the difference between whites and reds, what chance do I have? But despite this knowledge, I cannot suppress this automatic response to wine colour, which Brochet described as “a perceptual illusion.”2

The fact that we may not be able to tell the difference between whites and reds based on taste and scent alone doesn’t mean that wine colour is irrelevant. In fact, it demonstrates just how central colour is to shaping our experiences of wine and how vital colour is to sensory perception. As Ronald S. Jackson points out in Wine Tasting: A Professional Handbook, “Colour is such is a critical element in sensory memory that identification may become markedly distorted without it.”3 Under the larger umbrellas of white and reds, specific hues within each category can deeply affect our sensory expectations and associations and, by extension, inform how we ultimately understand a particular wine. Fully harnessing the potential of this perceptual phenomenon to create wines that speak to consumers requires thorough colour measurements to evaluate the colour quality of each wine.

Wine colour relies on not only the raw materials used to make the wine, but the processing and aging of the wine. Image Source: Pexels user Jason Hughes

Factors Impacting Wine Colour

The colour a wine takes is the result of both its innate qualities and ongoing environmental influences throughout the lifespan of a wine. The type and variety of grape, where it is grown, its growing conditions, its maturity at harvest, and its physical properties all have a significant impact on the hue the wine will eventually acquire. Processing of the grapes, bottling, and storing of the wine introduce a host of new factors that will shape colour, including phenol composition, alcohol level, oxygen and sulphate dioxide concentration, temperature, anthocyanin to tannin ratios, and the natural aging process.4

As such, colour can serve as a kind of visual history of a wine, signaling its age and quality and alerting the wine producer to potential issues should it not conform to colour expectations. Often, wine producers will use a spectrophotometer to measure the spectral absorbency of wines in order to determine whether or not it is performing as it is meant to at various stages of production. For example, young red wines typically reach maximum absorbency at 520nm, but as it ages “the maximum absorption decreases” from 520 nm and increases at 420 nm, the yellow colour region. This explains the shift in well-aged wine from a red to an orange hue, and brick red colour.”5 Premature darkening of red wines may be an indicator of compromised quality and require a reassessment of production methods. However, while the spectral absorption method of colour analysis can be used by wine producers to monitor colour as abstract data for purposes of process analysis, spectral absorption does not necessarily correlate to human perception of wine colour and our attendant sensory response.

Correlating spectrophotometric data to manufacturing variables can give wine producers valuable information to improve their harvesting and processing methods. Image Source: Unsplash user Jassy Onyae

Measuring Wine Colour to Enhance Sensory Perception

To more reliably analyze wine colour for the purposes of sensory enhancement, a spectrophotometrically-based method that combines instrumentation allowing for analysis of colour over “the full range of the visible spectrum” with specialized software to calculate CIE L*a*b* values is needed. Designed to mimic the way humans see colour, this measurement method allows researchers and wine producers to meaningfully quantify wine colour as it is perceived by the human eye. The data produced can be used to evaluate the quality of a particular wine while also facilitating a precise combination of blended wines, which now represent “some of the most sought-after wines in the market today.”6 More importantly, this data may be used to create industry colour standards that Jackson believes would “increase the value of colour in sensory observation.” As a result, wine producers would be able to tailor their production methods to enhance the sensory appeal of their products to consumers and colour could become a more stable and meaningful indicator of smell and taste.

The HunterLab Difference

HunterLab’s advanced range of spectrophotometric instruments and software packages offers wine producers the most reliable and sophisticated methods of evaluating wine colour available today. As leaders in the field of colour measurement for over 60 years, we have distinguished ourselves for both our technical innovation and our responsiveness to the needs of our customers. Contact us for more information about our products and how we can help you enhance your production methods and, ultimately, the experiences of your customers.