Odor as an indicator of wine quality: Mapping the sources

Most of the stock photographs of wine notables that you encounter show them holding a glass of wine to their noses.  This is no accident as wine odor is one of the key markers of wine quality and they want to be shown either assessing the quality of the wine or wallowing in the enjoyment that accrues to a person who is fortunate enough to be sniffing a high-quality wine.  According to Vincent Ferreira (Laboratory for Flavor Analysis and Enology, University of Zaragoza), "The most relevant notes of great wines are caused by complex associations of aroma compounds playing different notes ..."  And it is these compounds and their notes that will be the focus of a series of posts (beginning with this one on the sources) on odor as an indicator of wine quality.  The arrow on the figure below shows our current position on the Wine Quality Assessment Framework.

We begin with some baseline definitions.  An odor is a volatile compound, or combination of volatile compounds, that stimulates the olfactory organ to register a smell.  The odor threshold of a compound is the lowest concentration at which its smell can be detected.  The perception threshold is the minimum detectable concentration for 50% of a group of tasters while the recognition threshold is the minimum concentration of that compound necessary for identification of the odor.

If we relate the foregoing to wine, quality wine can be characterized as having complex associations of aroma compounds that exceed the odor threshold; and, for a subset of tasters, exceed the recognition threshold.  But what are the sources of these odor?  The figure below shows the sources of wine odors.

As the figure shows, wine odors are a sum of the odors from the grape, maceration, yeasts, alcoholic fermentation, malolactic fermentation, and aging.  The Wine Institute characterizes these odors as shown in the table below.

Over the course of the next few posts I will detail the elements that ensure the production of quality wine grapes, characterize the sources of wine odor, and, finally, show how the interaction of these odor compounds aid in the perception of a quality wine.


© Wine -- The View From Orlando

Appearance as an indicator of wine quality

I recently developed and reported on a framework for the assessment of wine quality, a position at which I had arrived rather tangentially.  I was writing a post on wine balance as a quality measure and, upon concluding, realized that I had not defined quality as a concept or wine quality as an ideal.  Over the course of two subsequent posts I corrected these oversights and then returned to the task of elaborating the components of balance as contributory inputs to wine quality.  My starting point for these discussions, as shown in the quality assessment model below, was fairly "deep in the belly of the beast."  In my future posts on this topic I will be working in a more structured, top-down manner beginning with today's post on appearance as a wine quality marker.

There are two main factors to be considered when visually assessing a wine in terms of quality: clarity and color.

Clarity

According to the WSET® standards, clarity can be categorized as either clear or dull.  Most of the wines available commercially are pretty clear because, especially in the U.S. market, there is a "finickiness" about consuming products that are cloudy, or dull, or impregnated with suspended particles.  The factors which can contribute to dullness in a wine include: cloudiness/haze, bubbles, and suspensions.

Cloudiness

Cloudiness, if not the specific intent of the winemaker (e.g., Scholium Project, selected Gravner wines), could be the result of improper racking/clarification or protein instability.  Most wineries rack their wines from container to container in order to separate it from solid elements that have sedimented out of solution (There is, of course, an oxygen-exposure element to some racking but that is outside the scope of this discussion.).  Intuitively, there will be higher concentrations of large solids sedimenting out of the wine in the earlier stages of storage and then slower sedimentation rates with the passage of time as fewer and fewer large pieces of insoluble material remain in the wine. Some wineries will introduce fining agents such as egg white, bentonite, or isinglass which bind with proteins and fall to the bottom of the containment device.  Some of the flavor elements in the wine exists as solids and some winemakers refuse to fine because of fear of this process diminishing the wine's flavor profile.  If racking and fining does not clear up the wine, the winemaker may resort to filtration.  Again, many purists decry filtering because of fear of "flavor-napping."

A second potential source of cloudiness in wine is protein instability.  According to Dr. Bruce Zoecklein, Enologist at Virginia Tech (and my go-to guy), the major source of protein in wine is the grape and amounts can range between 10 and 275 g/l (Protein Stability Determination in Juice and Wine). White wines have large insoluble proteins which precipitate out of solution imperceptibly.  The more rapid precipitation, which is visible as protein haze, is, according to Dr. Zoecklein, probably the result of protein-flavonol bonding.  Addition of bentonite in the winery can eliminate this protein haze.  Some of the proteins in the solution may precipitate out if the wine bottle is subjected to heat and would manifest as the cloudiness/haziness that would render the wine's quality suspect in the eyes of the consumer.

Secondary Fermentation

If the wine is not a Vinho Verde (young, easy-drinking wine from the Minho region of Portugal), or a designated sparkling wine, it should not contain bubbles.  Bubbles in a still wine is an indication of secondary fermentation in the bottle, a situation that occurs when the wine is bottled while still containing appreciable levels of residual sugar and viable yeast cells.  Under the appropriate conditions, the yeast will begin to ferment the residual sugar (because that is what yeasts do) producing alcohol and releasing carbon dioxide in the process.  Given the anaerobic environment within the bottle, the carbon dioxide dissolves into the wine and will alert to its presence either by pushing the cork up through the capsule, causing the bottle to explode, or manifesting as bubbles when the wine is poured into a glass.

Suspensions

One potential suspension in a wine glass is sediment.  Now sediments are, of course, not harmful if ingested but if encountered in a glass poured in a restaurant the consumer should be teed off.  As wines age, pigments precipitate out and fall to the bottom of the bottle.  Ending up with a mouthful of sediment is an unpleasant feeling and is one of the reasons that older wines should be carefully decanted before being poured into wine glasses.

Another "deposit" which can sometimes be found in wine is tartrate crystals (sometimes called wine diamonds).  Wine contains both tartaric acid and potassium and under cold conditions they combine to form potassium bitartrate crystals.  These are harmless but unattractive to U.S. consumers so winemakers cold stabilize the wine in stainless steel tanks to force the crystals to form in a controlled environment.  The crystals formed in this manner adhere to the sides of the stainless steel tanks and the wine is then poured off leaving the crystals behind.  If a wine is not cold stabilized prior to bottling, tartrate crystals could precipitate out if the wine is subjected to very cold conditions.  Scch crystals, when they occur, are normally found on the underside of the cork or suspended in the wine.

Color

According to the Wine Spectator (Inside Wine: Color), consumers associate darker-hued red wines with greater quality and winemakers are responding to this perception by pursuing viticultural and vinicultural practices that result in wines with the color the customers are demanding.

The color in red wine comes from pigments called anthocyanins which reside in the skin of the berry and provide the red, blue, and purple colors associated with the fruit.  Red varieties such as Syrah, Cabernet Sauvignon, and Petite Sirah have higher anthocyanin concentrations than do varieties such as Pinot Noir and Nebbiolo.  Viticultural techniques such as yield reduction, foliage removal, and control of vegetative growth can yield grapes with darker color while vinicultural practices such as pre-fermentation cold soak, pumping over, andy punching down all seek to extract as much color (tannins and flavor) as possible from the skins (White wines are not generally brought into contact with their skins).

In general, white wines are colorless when young, gaining a brownish tint as it ages.  Red wine should be purple to ruby when young, browning as color sediments out. A young wine with a brown color could be manifesting the effects of oxidation.


© Wine -- The View From Orlando

The role of tannins in wine balance

Wine quality, as perceived by the consumer, has a number of elements, an important one of which is wine balance.  I have defined wine balance in a previous post but will reproduce Dr. Bruce Zoecklein's (Virginia Tech Enologist) Palate Balance Equation here to highlight the included elements.

              Sweet ⇄ Acid + Phenolics (Astringency and Bitterness).

I have treated the sweet (alcohol) and acid elements of this equation in prior posts and will focus on the phenolics element in this post.  The placement of phenolics (tannin) and wine balance in the quality assessment framework is indicated by the arrow in the figure below.

So what are tannins?  According to the indefatigable Dr. Zoecklein (Enology Note #116), tannins are "a heterogeneous group of phenolic compounds" with properties to include: astringency (caused when the tannin binds with protein in saliva; evidenced by mouth pucker and a bitter aftertaste); bitterness; the ability to react with ferric chloride; and the ability to bind with proteins.  A key characteristic of phenols, according to Dr. Zoecklein, is the ability to associate with (polymerize, in scientific lingo) themselves and other compounds thus yielding larger molecules.  The degree of polymerization (an actual metric) tends to increase with the passage of time.

There are two main types of tannins: hydrolizable and condensed (more properly called proanthocyanidins).  Hydrolizable tannins are found in the bark of oak and other plants and are formed in the growing tree for the purpose of food storage. These tannins are called hydrolizable because they can be broken down into smaller components in the presence of an acid or water.  Condensed tannins are insoluble and are found in tea, pomegranates, and the seed, skins, and stems of grapes.

Grape tannins are a combination of compounds (cathecin, epicathecin, epigallocathecin) which link up in chains and of which at least two need to be present for the compound to be termed a tannin. Seed tannins weigh, on average, 3.5 - 5mg per berry while skin tannins weigh in between 0.5 and 0.9 mg.  Seed tannin polymers are shorter than skin tannin polymers (the longer the tannin chain the higher the astringency) yet seed tannins are perceived by winemakers to be harsher, greener, and more astringent than skin tannins and that is evidenced in the way that the berry is handled once it enters the winery.  Oak tannins are astringent in tree matter and need to be seasoned and toasted -- as a part of the barrel treatment -- in order to increase their usefulness.

Grape tannins accumulate during the first period of berry growth with skin tannin synthesis beginning earlier than seed tannin synthesis and then ending with the conclusion of the first phase of growth. Seed tannin synthesis continues into the early period of berry ripening before concluding.  Both skin and seed tannins continue to mature during the berry ripening phase.

Tannins release is a function of how the grapes are handled in the winery.  Tannins are not desirable in white wines so white wine grapes are pressed lightly and there is no contact between the juice and skin.  In the case of red wines, tannins are desirable for color, mouthfeel, and aging and there is extensive skin contact. The amount of tannins released are a function of skin thickness (Cabernet Sauvignon, Nebbiolo, and Syrah are thick-skinned and thus release more tannins than do thin-skinned varieties like Pinot Noir, Gamay, and Cabernet Franc), the length of maceration, and the number of cap punch-downs to which the must is subjected.  Skin tannins release early and easily (as they are water soluble) but then plateau.  Seed tannin release is slow, steady, and long and requires alcohol as a solvent.  Once grape tannins are in solution, 80% of them undergo one or the other of the structural changes listed below:

• Tannin-tannin linkages
• Oxidative change
• Acid-catalyzed reactions
• Bind with anthocyanins (color compounds) to form polymeric pigments that ensure long-term color stability
• Formations that provide structure and mouthfeel to wines.

Grape tannins provide color, flavor, structure, and texture to the wine and serves a preservative function.  Oak tannins play an essential role in wine maturation in that they: (i) promote oxidation products (react with oxygen in the presence of a transitional metal to release activated oxygen which, in turn, oxidizes alcohol to acetaldehyde);  (ii) produce astringency; and (iii) aid in the removal of off-notes.  Tannin-anthocyanin complexes sediment out of wines as they age resulting in browner, less tannic wines.

Tannin affects wine balance in the following ways:

• The lower the tannin levels, the greater the amount of acidity the wine can support; conversely, the higher the tannin levels, the lower should be the acidity
• High-acid, high-tannin wines tend towards astringency
• Too much tannin results in wines that are heavy on the palate, lacking in finesse, and possessing a rough finish
• Increasing alcohol content increases the intensity of bitterness and decreases the sensation of astringency
• Low alcohol levels will result in dominant acidity and astringency and harsh, thin wines
• Lowering wine pH increases the astringency of the tannins.

The winemaker has a number of tools at his/her disposal to increase/reduce tannin levels as required and I will discuss those tools in a follow-up post.

© Wine -- The View From Orlando

The role of alcohol in wine balance

Wine balance is one of the important measures of wine quality and attainment of said balance, according to Dr. Bruce Zoecklein (Virginia Tech oenologist), requires the harmonic functioning of each element in the Palate Balance Equation reproduced below. The arrow on the figure following the equation illustrates where balance and alcohol fall within the wine quality assessment framework.

              Sweet ⇄ Acid + Phenolics (Astringency and Bitterness).

Fortunately for wine drinkers, the structure that grape vine plants have evolved for the protection and nourishment of their genetic-material-carrying seeds, also serves as the raw material for the drink of their choice.  At harvest, the vitis vinifera berry has the following composition (Murli Dharmadhikari, Director and Enologist, Iowa State University Extension):

• Water (70 - 80%)
• Dissolved solids
• Sugar (primarily glucose and fructose; 150 - 200 g/L if ripe)
• Organic acids
• Phenolic compounds
• Nitrogenous compounds
• Aroma compounds
• Minerals
• Pectic substances (primary role is cementing plant cells together).

The dissolved solid of interest herein is sugar so we will focus exclusively on that topic for the remainder of this post.

Sugars exist in the grape vine as sucrose (a one-to-one bond of the single-molecule sugars glucose and fructose) and are transported to the berry from the vine where it is metabolized.  As the berry develops (see figure below), the vine-sourced sucrose decreases in volume and is replaced by carbohydrates from surrounding leaves.  Once in the berry, sucrose is separated into its constituent parts by the enzyme invertase.

As the figure below shows, xylem flow (water and nutrients from the roots) to the berry stops shortly after veraison but the flow of nutrients from surrounding leaves (via the phloem) continues through the bulk of the ripening phase.  As the figure shows, the sugar, measured in °Brix (the sugar-content metric used in the US; % sugar by weight), begins to accumulate in the berry post-veraison as sugar consumption declines.  The sugar content at berry maturity can range between 12 and 28% with the optimal level for harvest falling between 19 and 25 Brix.

Grape berry development (Source:www.extension.org)

In a 1966 study, W. Mark Kliewer of UCDavis concluded that the following sugars resided in a mature grape berry: Stachyose, Manninotriose, Raffinose, Melibiose, Maltose, Sucrose, Galactose, Glucose, and Fructose.  With the exception of glucose and fructose, all of the sugars are found in minute amounts and do not contribute in any way to the sensory characteristics of fermented wine. 

Glucose is a 6-carbon-atom sugar resulting from the breakdown of sucrose by the berry and is the first sugar to be broken down by the yeasts during the fermentation process.  There is 5 times more glucose than fructose in the berry at the beginning of the ripening stage but the levels are about equal at the time of harvest due to rapid fructose accumulation in the later stages of berry development.  Through its participation in the development of glycosides, glucose plays a role in the flavors of wine based on the interaction of those glycosides with phenolic compounds such as anthocyanins and terpenoids.  Fructose is twice as sweet as glucose and is a key component in the sweet sensation of wine.  Depending on the time of harvest, the ratio of glucose to fructose in the berry will vary: In an unripe berry, glucose will be dominant; at the ripening stage, the levels will be even; if the grape is over-ripe, fructose will dominate; and if the grape is ripe, the levels will vary depending on whether the variety is high-fructose (e.g., Chardonnay and Pinot Blanc) or high-glucose (e.g., Chenin Blanc and Zinfandel).

Wine is a result of using yeasts (Saccharomyces) in an anaerobic (oxygen-free) environment to convert the sugars from the pressed grape juice into ethanol in the two-step process illustrated in the figure below.  The first step -- glycolysis -- results in the 6-carbon glucose being split into two 3-carbon pyruvate molecules.  In the next step --- alcoholic fermentation - four atoms of oxygen and two atoms of carbon leave the pyruvate, resulting in acetaldehyde which is converted into ethanol.

Alcoholic fermentation (Source: http://alcoholicfermentation.net/) 

Wine is never fermented completely dry as sugars such as xylose and arabinose survive the fermentation process unscathed.  The amount of alcohol produced as a result of fermentation is directly related to the amount of sugar present in the juice initially.  The conversion ratio is ºBrix x 0.55 = alcohol in wine (Dr. Dharmadhikari).  Residual sugar is the measure of sugar solids remaining after alcoholic fermentation and is stated in g/L.  For dry wines the residual sugar ranges between 0.2 and 0.3 g/L while the measure for sweet dessert wines ranges between 5 and 15 g/L.

In wine, the sweetness of sugar balances out the bitterness of phenols.  Sweetness is perceptible by humans at around 1% of volume but that perception is dependent on the size of the sugar molecule. Both fructose and glucose are single sugar molecules and are perceived as sweet by humans because they fit neatly into the receptors on the tongue.  Carbohydrates, on the other hand, are long chains of sugars, do not fit neatly into the receptors on our tongues, and are not perceived as sweet.

As stated previously, wine balance is viewed as a key indicator of wine quality.  If a wine has insufficient sugar in relation to its acids and phenols, it will present as harsh and acidic and will retard the evolution of flavors in the mouth.  In such a case the winemaker may choose to add sugar (chaptalize) in the form of cane sugar (sucrose in cane sugar is inverted by the enzymes present in the wine and converted into glucose and fructose) or corn sugar (dextrose which will be fermented quickly by the yeasts).

Alcohol adds to the sensation of sweetness in a wine. It also adds a thickness. Too much alcohol and the wine can present as hot, lead to a reduced perception of wine aroma, and can impart a sense of intoxication.  For a winemaker doing business in the US, there is an approximately $.50 difference in the taxes paid per gallon of produced wine if the alcohol level goes beyond 14.001%.  If the winemaker believes that the wine would benefit from de-alcoholization, there are three methods available to him/her: reverse osmosis, spinning cone, and adding water.  These methods will be discussed in greater detail in a subsequent post.

Hopefully the normal grape-growing and alcoholic fermentation process would have produced a balanced wine but if an imbalance were brought about by an insufficiency or excess of alcohol, the winemaker has tools available to address the problem.

© Wine -- The View From Orlando

Development of A Framework for the Assessment of Wine Quality

My current objective is to develop of a framework for assessing wine quality and that effort was launched with yesterday's post on the definition and high-level scope of wine quality.  I herein examine three efforts which seek to define the elements of wine quality and then use the learnings resulting from these explorations to construct a broad-based framework for the assessment of wine quality.

The first study considered was Stephen Charters study titled The Intrinsic Dimensions of Wine Quality: An Exploratory Investigation.  In this study the author conducted interviews and focus groups with 105 participants and, as a result of that effort, developed the quality dimensions contained in the figure below.

The Dimensions of Wine Quality (Source: Figure 1 of The Intrinsic Dimensions of Wine Quality)

The study did uncover some extrinsic wine quality factors (appellation systems, classification systems) but the focus was on development of intrinsic factors -- those identified in the glass when the wine is consumed.  It should be noted that this study was conducted in Australia using Australian participants and Australian wines.

I have a number of concerns with this study.  In my earlier post on defining the wine quality space, I indicated that customers with objective knowledge use objective cues to define quality.  In this study, the author used 105 individuals (60 consumers, with the remainder divided between wine producers and other wine industry players) with the consumer participants categorized as low-involvement (24), medium-involvement (25), and high-involvement (11).  With this obvious disparity in objective knowledge, the likelihood of getting solid input on intrinsic factors is low.  And the results bear this out.  As can be seen in the figure, a number of the components appear to me to be non-objective (drinkability and pleasure, for example) and most lack a sense of dimension (How do you measure drinkability?).  So, while the model is good for directionality, the questions raised render it unsuitable for our purposes.

The second model explored was Richard Leahy's Components of Wine Quality which appeared in a December 19, 2011 post on crushpadwine.com/blog.  Leahy divides wine quality factors into two camps: primary (sensory) parameters of wine quality and secondary elements of wine quality.  In that the scenario he describes entails judging a large group of wines, I will assume that these are intrinsic wine quality factors.  The components are, according to Leahy:

Primary Elements                  Secondary Elements
Visual                                    Balance
Aroma                                   Intensity
Taste                                     Length
Texture

My issues with this list is that: (i) it only considers intrinsic quality elements; (ii) it is presented at too high a level; and (iii) no potential values are presented for the identified elements.  Also, no material is presented which allows one to assess whether a wine is of low or high quality.

The final model evaluated was the WIne and Spirits Education Trust (WSET) Systematic Approach to Tasting Wine.  A copy of the tasting sheet, showing the categories, and potential values associated with each category, is presented below.

A few points of note: (i) This mechanism is clearly targeted at the objective individual; (ii) it clearly identifies each of the categories that exists in its model and provides potential values for each; and (iii) it posits that an assessment of quality is a journey rather than a eureka moment.  In the case where a product is being assessed for quality, the metrics associated with each parameter is provided  so thatthe customer can assess that parameter against his or her requirements.  For example, in the case of a car, the parameter miles per gallon will come with a number, 26 let's say.  In the case of wine quality assessment using this tool, we know the parameter but the value or metric associated with that parameter has to be teased out through tasting; metrics cannot be assigned to flavors or flavor intensity until the wine is tasted. For someone who is appropriately trained in the method, a quality bottle of wine would have the following characteristics:

• Appropriate quality
• Intensity and color befitting its age and variety
• Clean nose
• Intensity, development, and aroma characteristics befitting its age and variety, as perceived by the taster
• Sweetness level appropriate for the wine style
• Balance between variety, tannin, and alcohol
• Body appropriate for the varietal and wine style as perceived by the taster
• Medium-to-pronounced flavor intensity
• Flavor characteristics that are appropriate to the variety, style, and age of the wine.

Based on how well the taster feels that the wine addresses the above characteristics, it can be rated as having poor, acceptable, good, very good, or outstanding quality.

The WSET approach is comprehensive and allows an objective taster to arrive at a quality conclusion about a specific bottle of wine at a specific time.  It is conceivable that someone else tasting that same bottle may arrive at a different conclusion but that illustrates human differences (number of taste buds, for example) rather than being an inherent weakness in the approach.  The shortcoming of this approach is that it does not take account of the vast majority of consumers who will never use it.  That is to say, its lack of extrinsic quality components renders it unusable by the wine drinker who is equipped with subjective knowledge.

Let's stop at this point and take stock of the situation.  I have shown that the quality of a wine can be derived using the WSET Systematic Approach to Tasting Wine.  That tool is only suitable, however, for individuals with pertinent, objective knowledge, leaving the large mass of the wine drinking public to its own devices as it relates to assessing the quality of wine.  And assessing the quality of wine is not a parlor game; it is more often than not a precursor to a purchase decision.  A comprehensive wine quality assessment has to address the unaddressed issue in the WSET tool and provide a mechanism for the assessment of wine quality by those with a subjective bent.  We have identified a number of these subjective cues and have coalesced them with the WSET tool to create a comprehensive wine quality assessment framework.  The proposed framework is illustrated in the figure below.

The extrinsic cues can be used either singly or in combination by the customer in order to arrive at quality decisions.  For example, the customer may use the objective opinion of the wine critic as an indicator of quality and use that as a basis for a purchase decision.  Or, on the other hand, the customer may use pricing and vintage cues in order to make that decision.

In closing, I would like to note that quality in the world of wine differs from quality in most other products and services because of the variability in terroir, production methods, and, most importantly, the differences in perception that accrue to us a result of our human condition.  Wine quality, at the end of the day, is a truly personal assessment.

I will be reviewing the various elements of the wine quality assessment framework in future posts.

© Wine -- The View From Orlando

A Framework for the Assessment of Wine Quality: Defining the Space

In my most recent post I wrote about balance as a measure of wine quality and promised to detail its constituent components in follow-up posts.  As I was mulling over my approach to fulfilling this promise, it occured to me that I had not provided a context for the quality discussion.  I will correct that oversight in this blog post by developing a wine-quality framework and will discuss the wine balance components in subsequent posts.

Before we begin depiction of the wine-quality framework, I will explore some definitions of the quality concept.  ISO, the Geneva-based, international standards-setting organization, famed for development of the ISO series of quality standards, avers that "The quality of something can be determined by comparing a set of inherent characteristics with a set of requirements.  If those inherent characteristics meet all requirements, high to excellent quality is achieved."  If the requirements are not met, ISO stipulates that the product or service provided is of low or poor quality.

According to what-is-quality.com, the formal definition of quality in the U.S. is "the characteristics of a product or service that bear on its ability to satisfy stated or implied needs.  A product or service that is free of deficiencies."

The two definitions are congruent in that they both address quality levels (high and low quality in the case of ISO and quality/no quality in the case of the U.S.) but they appear to differ in the degree of rigor associated with requirements-identification.  ISO refers to a set of requirements while the U.S. standard refers to stated needs, which gives the impression of customer-driven requirements.  But the U.S. standard further refers to implied needs inferring, in my opinion, that by buying a product or service, a customer is admitting to a set of needs, regardless of whether those needs are formally stated or not.

According to Clodfelter and Fowler (Do Consumers' Perceptions of Product Quality Differ from Objective Measures of Product Quality?), "Quality is a multi-dimensional construct that cannot be equated with or measured by a single cue or attribute." In assessing quality, customers call on objective (accurate and current information on relevant measurable and verifiable standards) or subjective (their judgement about a product's/service excellence) knowledge.  Individuals with objective knowledge will respond to intrinsic -- cannot be changed without changing the nature of the product or service -- cues while the consumer with subjective knowledge will respond to extrinsic -- related to, but outside of, the offered product or service. In the wine world we can think of minimum alcohol level as an intrinsic cue and price as an extrinsic cue.

With quality defined in the foregoing, we should be pivoting to an identification of the elements of wine quality.  But it is not that easy.  The first level of difficulty is encountered when seeking a consensus on the elements that should be included in a wine quality framework; or whether quality should be broadly discussed at all.  The great French oenologist Emile Peynaud, for example, felt that quality was such a personal thing that it only existed in relation to an individual.  In the cases where components of quality are identified, no qualitative or quantitative values are associated with the components.  And, finally, no attempt is made to differentiate between the relative contribution of each component to the overall quality measure.

I will examine a number of wine quality schemas and propose a comprehensive framework in my next post.

© Wine -- The View From Orlando