How do you determine a good cork ?

That was the question posed to a diverse group of wine consumers and restaurant employees in a recent study. The research was sponsored by one of the California Wine Industry’s quality leaders, who with the assistance of three major cork suppliers, held a series of focus groups concerning attitudes toward wine corks.

The research was based on a three-part interview of premium wine consumers and restaurant employees who regularly recommend and serve wine. These results are provided courtesy of Amorim Cork America, Portocork America and Cork Supply, USA.

Summary of Findings

Most Participants, both consumers and wait staff, volunteered that corks serve the primary purpose of sealing the wine so that it does not leak. Some consumers and to a greater extent restaurant wait staff, perceived natural corks as a means to allow enough oxygen exchange to facilitate the aging process. Many in both groups saw corks as a “traditional” component that added general romance and sophistication to the wine. Most respondents had definite and positive opinions about the proper feel, sound and appearance of a “good” cork.

The overwhelming criteria used to judge the quality of cork centered on extraction characteristics. Most importantly, participants wanted a cork that is moist and can be easily extracted without breaking or crumbling. Corks that are moist and more pliable were strongly preferred over brittle, dry or hard to remove corks. Other criteria mentioned were:

• Length - medium to long is better than short.
• Coating - waxy and slippery is best - easy to extract and replace.
• Texture - porous is good - but not too porous.
• Printing - text or graphics strongly preferred.
• Color - lighter is better (especially with consumers)
• Absorbency - like to observe wine color and smell without saturation.
• Real Cork - prefer natural materials over synthetic.

When asked to judge individual corks both groups ranked the two highest classifications (A’s and B’s) ahead of all other corks regardless of length or washing treatment. All corks in these categories received over 80% positive ratings.

The two lowest quality grades (C’s and D’s) received between 40% and 50% positive ratings. Samples of colmated and agglomerate corks were rated in the middle - with positive ratings between 55% and 75%.

I. Characteristics of a High Quality Cork

Part One of the interview called for the respondents to describe what characteristics they felt were most important to a high quality cork. The responses were not prompted and the answers were recorded verbatim. There were a total of 159 responses that were summarized into 15 different categories. These 15 responses are further grouped into the 5 general topics listed below. The topic and the corresponding frequency of response are displayed.

Criteria for judging cork quality as a percent of total responses

Rank	Criteria	%
1	Extraction Characteristics	57%
2	Physical Appearance	19%
3	Wine Absorption	19%
4	Physical Dimensions	10%
5	Natural Materials	3%

Extraction Characteristics:
The most important criteria for consumers and the trade centered on qualities having to do with extraction. The consumer groups’ most frequent response cited “does not crumble” and “easy to extract and replace”. The restaurant groups most frequently mentioned that they desired a cork that is “moist and supple". The consumers showed a definite interest in how easily a cork can be replaced into the bottle. Their ideal cork is sealed tightly enough to create the traditional sound when pulled, but not so tightly that it might break or crumble during extraction.

Physical Appearance:
Generally more important to consumers than the trade, the overall response showed a strong preference for text or graphics printed on the cork. The consumers also preferred lighter coloring and associated lightness of color to overall quality. The trade groups were not so concerned with color or printing and primarily discussed the “texture” of the cork as the most important visual characteristic.

Wine Absorption:
Both consumers and the trade felt that a good cork should absorb some portion of wine. They felt this aided the practice of sniffing the cork. Both groups described “porosity” as a critical factor.

Physical Dimensions:
Both consumers and the trade consider longer corks to be of higher quality than shorter corks. Some participants did mention that they disliked some of the extremely long corks because they have a tendency to break if the cork screw cannot reach to the bottom.

Natural Materials:
Consumers appreciated the “natural” quality of cork. They felt that the wine cork provides an important component of the ceremony and tradition of the wine experience. Some trade comments were negative towards plastic stoppers, with the majority of complaints concerning difficulty of extraction.

II. Quality Rankings of Specific Cork Samples

Part Two of the interview consisted of ranking various types of cork based on their perceived quality. Each respondent was asked to examine nine different corks and assign them a quality level of “High", “Medium” or “Low”. The respondents could assign as many corks as they wished to any category.

The results are summarized here using the combined percentage of responses to “High” or “Medium” quality. All the corks of grade A and B received over 80% “positive” rankings. All the corks of grade C and D received less than 50% “positive” rankings. In the middle were a colmated cork and a twin top agglomerated cork. The attached displays 2A-C show the detailed responses.

• Top Visual Rankings - over 80% Positive

  95% - Grade A 1.75” Light peroxide wash
  89% - Grade B 1.75” Chlorine wash
  88% - Grade B 1.75” Light peroxide wash
  83% - Grade B 2.00” Light peroxide wash (1)
  

• Mixed Visual Rankings - between 50% and 80% positive

  75% - Colmated 1.75” Light peroxide wash
  55% - Agglomerated 1x1 1.75” Light peroxide wash
  

• Low Rankings - less than 50% positive

  44% - Grade C 1.75” Light peroxide wash
  43% - Grade D 1.75” Light peroxide wash (2)
  40% - Grade C 2.00” Light peroxide wash (1)
  

(1) The two inch corks generally received more “high quality” rankings than their 1.75” counterparts. A small but significant number of consumers (16%) ranked the longer corks at the “low” level. Presumably the rankings are a manifestation of concern about ease of removal and replacement of the longer cork.

(2) Grade “D” corks received the lowest ranking among the restaurant employees but the consumers group, ranked the “D” grade higher than both “C” corks. This may be a manifestation of an opinion mentioned by some consumers that “a good cork has pores in it”.

Terminology:

Washes refer to the rinsing procedure and color for each cork. The “light peroxide washes” possessed a “natural” color. The chlorine wash was several shades lighter in color.

Colmated Corks describe corks that have undergone a process in which the pores and imperfections have been filled with cork material.

Agglomerated Corks describe corks consisting of two natural cork disks located on both ends of a centerpiece comprised of granulated cork,

III. Benefits of Natural Cork

Part Three of the interview consisted of an examination of what perceived benefits are offered by natural cork Most participants, both consumer and restaurant staff, volunteered that cork serves the primary purpose of sealing the wine. Other perceived benefits that were mentioned included the following:

1. seen as “traditional” and adds to general romance and sophistication
2. prevents oxygen from spoiling the wine
3. facilitates the aging of wine
4. can be used to re-seal the wine
5. provides an early warning of a wine’s quality once extracted
6. adds authenticity to a wine (with name/logo or vintage printed)

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Methodology
This study was commissioned by an anonymous California winery and enacted by an independent research organization. Four groups were conducted in San Francisco and four groups were conducted in Chicago. Four of the groups consisted of consumers of premium wine and four consisted of restaurant wait staff personnel. Each focus group lasted approximately 90 minutes and contained 5 to 8 participants. This was a focus group study - directed at eliciting a depth of response. It is not a statistically projectable study.

Criteria for Consumer Group: 1. Between ages of 25 and 64; 2. Not employed in a competitive industry; 3. Having consumed wine for at least one year; 4. Having purchased and consumed at least one 750ml bottle of wine priced at $8 or $9 minimum in the past six weeks (depending on the market); 5. Having purchased at least 3 bottles of any wine in the past 6 weeks; 6. Personally open their wine at least 50% of the time; 7. Primarily use a cork screw to open wine.

Criteria for “Wait Staff” Group 1. Between ages of 25 and 64; 2. Not employed in a competitive industry; 3. Work full-time in a restaurant which offers a selection of wine; 4. Personally serve wine to restaurant customers; 5. Personally extract corks, primarily with cork screw, at least 20 times in the past 6 weeks; 6. Have served at least 20 bottles of wine and at least 5 bottles priced at $29 or $31 or more (depending on the market)