Portocork logo




560 Technology Way
CA, 94558
United States
(707) 258-3930
(707) 258-3935


Portocork is the premier supplier of natural cork closures to the North American wine industry. For nearly a quarter-of-a-century, our company has produced a wide range of natural cork closures, ranging from high-end still and sparkling wine cork to 1+1 and Microagglomerated cork products designed for value wines.

Portocork is proud to be the first in our industry to screen every single United States-bound cork bale for 2,4,6-trichloroanisole (TCA) using gas chromatography mass spectrometry (GC/MS). Since 2001, we have experienced an 80% reduction in TCA scores through the use of this technology.

Portocork was established in 1983 through a partnership between Portocork International and Fleming Packaging Group of Napa. The partnership continued until 1996 when Portocork International acquired 100% of Portocork America.

Portocork was a founding member of the Cork Quality Council (CQC) which was established in 1993 with the goal of continuing to increase quality standards and awareness of the benefits of natural cork. Portocork co-sponsored TCA research that was conducted jointly by the CQC and ETS Laboratories to establish a non-subjective cork testing methodology using GC/MS. Portocork continues as an active CQC member today.

Portocork International, located in Santa Maria de lamas, Portugal, is the world's most technologically-advanced producer of cork. Portocork has developed ultra-modern production facilities to process natural cork which is sourced only from company owned and leased natural forests that have existed in Portugal for decades. We control the cork from the time it is harvested until it arrives at your winery. This complementary combination of centuries-old natural practices and state-of-the-art production facilities, along with rigorous testing both in our ISO-9002 certified Portuguese facilities (with in-house GC/MS) and our California facility located in the Napa Valley, assures that our cork is the highest quality and most consistent cork year after year. Portocork America provides the world's finest cork.


Natural Cork Closures
Natural cork is a cylindrical stopper obtained by punching raw cork with manual or automatic machines.
download pdf

Twin Top® Closures
Twin Top® is a closure based on Champagne cork technology that has a granulated body with a disk of high-quality natural cork at each end.
download pdf

Neutrocork® Closures
Neutrocork® is a high-tech, competitively priced stopper designed for early-drinking still wines, light sparkling wines and beer.
download pdf

Champagne Stoppers
Champagne stoppers are closures designed specifically to meet the unique needs of Champagne and sparkling wine producers.
download pdf

FAQs About Our Products


Natural cork is a cylindrical stopper obtained by punching raw cork with manual or automatic machines. The stoppers are rectified to obtain the exact desired length, and then the various classes are selected by sorting with state-of-the-art optical cameras. After the sort the most important step, which makes Portocork stand out from other cork companies: every single bale of 10,000 corks are tested for TCA using GC/MS for TCA. Not only is it virtually unheard of to test every single bale, a key to our success is to test prior to washing which minimizes the possibility of cross contamination. The stoppers are then washed in an automated washing process which includes the use of hydrogen peroxide, dried with sterilized air, and then sorted again by manual selection to refine quality. Before the corks are counted into bags of 5,000 for shipment to California, another test using GC/MS is done on 40% of all cork bales. This rigorous standard, second to none in the Portuguese cork industry, is one of the many reasons Portocork America is the leading supplier of Natural cork stoppers to the United States wine market.


Twin Top® Closures

Introduced in 1997, Twin Top® is among the most successful technical corks ever developed. Based on champagne cork technology, it has a granulated body with a disk of high-quality natural cork at each end. Twin Top® is manufactured at Amorim's specialist production facility at Coruche in southern Portugal. With the capacity to produce over one billion corks annually, it is the world's largest cork factory. Unlike synthetic wine closures, Twin Top® retains much of the tradition and quality that wine consumers associate with cork. While not recommended for long-term cellaring of wine, Twin Top® has gained acceptance with many leading wineries due to its reputation as a high-quality seal with virtually no incidence of cork-related taint. The performance of Portocork's Twin Top® technical cork has been enhanced by the application of Amorim's proprietary ROSA steam distillation treatment. Routine testing of Twin Top® corks by ETS Laboratories in the USA and Stellenbosch University in South Africa, confirm average taint levels to be below detectable levels. Independent research by European and Australian laboratories has established Twin Top® as a top performer on all key parameters for storage of wine for up to two years. In a trial undertaken by the Australian Wine Research Institute, Twin Top® outperformed a large field of synthetic stoppers on parameters such as oxidation, ease of extraction and preservation of fruit attributes. More than five years into the Australian trial, the wine bottled with Twin Top® closures showed good retention of sulfur dioxide and no sign of either the reduced characters evident under the ROTE-sealed wine or premature oxidation evident under synthetic stoppers. The outstanding sealing ability of Twin Top® was confirmed in a study by the University of Bordeaux 2 in which Twin Top® demonstrated very low and consistent rates of oxygen ingress compared to other closures.


Neutrocork® Closures

Neutrocork® is the latest addition to Portocork's portfolio of high-quality cork closures. A high-tech, competitively priced stopper, Neutrocork® is designed for early-drinking still wines, light sparkling wines and beer. Since its launch in 2001, winemakers have embraced Neutrocork® as a natural cork alternative to synthetic stoppers. With a consistent diameter and regular shape, Neutrocork® creates an excellent seal and performs well on the bottling line and on the shelf. Its smooth good looks also make it attractive to consumers. Because Neutrocork® is individually molded from fine cork granules of uniform size, it shows very little variation in diameter. This increases production efficiency and reduces the costessential for a stoppers in the price-sensitive, high-turnover market sector. All granules used in Neutrocork® are made from natural stopper-quality corkwood and treated with Amorim's proprietary ROSA process to minimize the risk of TCA. A recent trial by the University of Bordeaux 2 found that Neutrocork® had consistently low rates of oxygen transmission. Its performance in this important area is far superior to synthetic closures, which allow oxygen to pass into the bottle at a relatively high rate, potentially leading to undesirable "oxidized" characters.


Champagne Stoppers

Champagne stoppers are closures designed specifically to meet the unique needs of Champagne and sparkling wine producers. Portocork Champagne stoppers come from a modern facility in northern Portugal called Amorim Champagne. The plant is capable of producing 450 million closures a year. Portocork's sparkling cork stopper has achieved worldwide recognition for bottling the most prestigious champagnes and sparkling wines around the globe. A result of intense scientific and technological research, Portocork's sparkling stopper has the highest levels of physical, chemical and enological performance. Its excellent mechanical behavior and ease of use in bottling make it an essential partner for champagne and sparkling wines.
Portocork - Premier supplier of Natural Cork
Portocork - Premier supplier of Natural Cork
Take a look behind the scenes of Portocork and learn what separates us from the competition.
All about Quality at Portocork
All about Quality at Portocork
Take a look behind the scenes of the rigorous quality control every cork goes through to insure we supply the best possible. Gain a better understand of what separates Portocork from the competition by spending these few minutes with us.
Laser Printing, Ink Printing and Fire Branding
Laser Printing, Ink Printing and Fire Branding
Learn more about the various formats Portocork can use to produce branding artwork in order of preference.
Short intro to Portocork's ICON CERTIFIED individual cork inspection process.

News Archive

Trefinos USA and Portocork Partnership
01 March, 2019

Offering technical corks utilizing Supercritical CO2 via its CWINE Brand

(NAPA, Calif.) – Portocork and Trefinos USA announce strategic partnership allowing Portocork representation of CWINE and COMPAC Technical cork stoppers in North America.

“Since establishing Trefinos USA with a permanent US presence in 2017, we’ve seen tremendous growth and acceptance from the market. We are very excited to be partnering with Portocork’s first class sales team to continue growing our CWINE and COMPAC line of technical corks. Their newly built, state of the art processing facility in Napa will allow us to continue to grow while maintaining our high level of quality and service.” Said Ron Angold, Trefinos Business Development Manager for North America.

“Trefinos has a proven history of innovation and quality when it comes to technical cork closures and their CWINE and COMPAC products are a testament to that. The combination of supercritical CO2 technology, three different permeability levels, and a product which is certified to have a minimum 75% natural cork results in a high-end technical closure that can be tailored to the winemakers needs. This is a great addition to our product portfolio and am looking forward to building on the already established success the Trefinos brand has already experienced in such a short period.” Said Dustin Mowe, President and CEO of Portocork.

Trefinos USA is a worldwide leader in the manufacturing of technical cork stoppers, offering supercritical CO2 for the eradication of TCA below detectable levels and over 150 other nondesirable aromatic compounds. Each cork has an individual guarantee and is offered in 3 different ranges of permeability, ensuring consistency from bottle to bottle.

Since 1982, Portocork has been the leading supplier of natural cork to the American wine, spirits and beer market. With innovation and quality at the forefront of our mission we strive to provide technical solutions to today’s market with reliable, high quality natural cork products coupled with best in class service.

For more information about please contact or

Napa’s Portocork protects health, reputation of wine corks
04 February, 2015

Portocork America already controls the North American market for producing natural cork stoppers, but not all of them are being sold to vintners. A growing number are finding their way into beer and hard spirits bottles.

Read the full article in the Press Democrat including interview with Portocork President Dustin Mowe

Portocork introduces laser printing for natural cork stoppers!
26 August, 2014

This revolutionary technology has the capability to add traceability and identifiable numbering and/or text to each closure making every cork unique. There is no ink on the cork surface or drying time necessary.

The most complex images will turn out clean and perfectly detailed giving you the flexibility to add virtually any logo or artwork to cork. Additionally, the lighter shading areas of some images can now be reproduced without compromising the darker lines, keeping the visual effect of your artwork true to its original form. Dates, serial numbers and other codes are also available should you wish to personalize each cork for traceability or authenticity purposes. The best part, the laser printing process is completely safe for your wine and the environment!

For more information, please call us at (707)258-3930 or send an email to to see samples of laser branded corks with your logo.

All about Quality at Portocork
08 April, 2014

Take a look behind the scenes of the rigorous quality control every cork goes through to insure we supply the best possible. Gain a better understand of what separates Portocork from the competition by spending these few minutes with us.

Portocork at WIN Expo - booth 242
25 November, 2013

We are excited to be showing at the NCWE again this year so please, stop by and say hi to our team! We will be in booth #242.

For more information about the North Coast Wine Expo click here:

Title Name Email Phone
Portocork Sales and Service 707-258-3930

Q: Why use cork as a wine closure?
A: Not only is cork the traditional and most popular choice for the world's finest wineries, cork is unique and a long-proven wine closure. No other stopper combines the inert nature, impermeability to liquids, flexibility, sealing ability and resilience of cork. A natural product, cork is also environmentally-friendly, renewable, recyclable and biodegradable. Premium cork manufacturers such as Portocork combine the natural qualities of cork with the latest technology to produce the ultimate wine stopper.

Q: Are all corks the same?
A: No. Wine corks are graded in up to seven levels of quality dependent upon the grade of the raw cork used as well as the production and quality-control process of the manufacturer. Corks also vary in shape and size as they are created for many different bottle types and products such as fortified, sparkling and still wines.

Q: What are cork manufacturers doing to improve the quality of their product?
A: Portocork's parent company the Amorim Group shares the mission of the entire cork industry to keep standards high. To fulfill their commitment to quality, Amorim invests more than $6 million annually in natural cork research and development with the goal of eliminating 2,4,6-trichloroanisole (TCA) from its wine corks.

Q: What guarantee does the winemaker have that the wine will reach the consumer in peak condition?
A: Industry standards are defined in the European Cork Federation's Code of Good Manufacturing Practice. The Portuguese Cork Industry Association has adopted a program, Cork 2000, to help individual producers comply with the standards. An independent auditor will assess producers for accreditation under the scheme. Winemakers buying from an accredited producer can be confident in the quality of the cork they purchase. Portocork's high standards set the benchmark for the code.

Q: As a winemaker, does it matter which manufacturer or supplier I buy my wine corks from?
A: Yes. As in all manufacturing sectors, each cork producer uses its own methods. At Portocork only tried and tested procedures are employed and only the most modern equipment and technology are used in processing the cork. Systematic and detailed laboratory tests are conducted throughout production. All the products used in Portocork's manufacturing process meet the most demanding international standards for quality, safety and contact with human food, including those of the United States Food and Drug Administration.

Q: If I buy good-quality corks from a reputable supplier, will that ensure the corks will always perform as required?
A: Portocork's manufacturing procedures ensure the quality of its product on dispatch to the winemaker. However, after receiving the corks, winemakers need to handle them carefully to ensure they remain in peak condition. Care also needs to be taken in the transporting of corks to avoid contamination and to maintain the correct humidity. Portocork provides guidelines on ordering, storing and handling of corks.

Q: What is the incidence of cork taint?
A: "Cork taint" is a misnomercork itself does not affect wine, but cork may become contaminated with TCA, a contamination affecting many food and beverage products worldwide that can migrate into wine and cause the taint. There is no definitive research that accurately determines the incidence of cork-related taint, although oenological studies suggest that 2-5% of wines are affected by some sort of taint, of which cork taint is only one factor. Random sensory testing of Portocork corks in 2005 revealed that from a sample of 24,000 corks, fewer than half a percentage point (0.48%) were defective. Portocork's goal is to reduce this number to zero.

Q: Can wine be affected by TCA only through the cork?
A: No. TCA is often referred to as "cork taint" which wrongly suggests that cork is the sole cause of TCA. However, TCA can be found in bottled water, wine bottled with screw caps, beer, spirits, soft drink, packaged food products and even raisins. TCA in wine may be due to contaminated oak barrels or corks, contaminated winery machinery or bottling equipment, airborne molds in the winery environment or molds in transport containers or even the home cellar.

Q: Is all wine spoilage caused by TCA?
A: No. There are no definitive figures on TCA contamination. TCA is only one type of wine spoilage. Some types of wine spoilage are wrongly identified as cork taint caused by TCA.
Back to FAQ Top

Q: Is it true that cork taint is caused by the widespread use of pesticides in the 1950s and 1960s?
A: Some researchers believe the historical use of pesticides containing compounds such as pentachlorophenol may be contributing to the TCA problem. However, these chemicals have not been used for maintenance of the cork forests for many years. Amorim has 40-year-old purchasing records that help identify the best quality cork sources and Portocork's manufacturing process is designed to thoroughly clean cork of all contaminants.

Q: How do champagne corks differ from natural corks?
A: Champagne corks are made from a single moulding of high-quality natural granulated cork, giving it uniform physical and mechanical characteristics. At one end these corks have two or three discs of fine natural cork. Natural corks are punched whole from the finest cork bark.

Q: What is a Twin Top® cork?
A: Twin Top® corks are known as technical corks to distinguish them from natural straight corks, which are punched in one piece from the bark. Technical corks are assembled from granulated cork. The Twin Top® cork has discs of fine natural cork at either end of the cork and a granulated cork body made from high-grade natural cork left over after cork punching.

Q: Is there a world shortage of cork?
A: There is enough cork in the cork forests of Portugal to last more than 100 years. The introduction of new products such as Twin Top® corks for commercial wines allows even better utilization of existing cork resources. Ongoing reforestation is increasing the cork forests by 4 percent every year.
Back to FAQ Top

Q: Are the cork trees cut down to obtain the material to produce wine corks?
A: No. To harvest the cork, the outer bark is stripped from the tree once every nine years and then the tree regenerates the bark. The cork industry is environmentally friendly and truly sustainable. Cork trees are only removed when decrepit with age or to reduce overcrowding.

Q: What is a colmated cork?
A: Colmated corks are made from lower-grade natural cork with larger lenticels or structural imperfections. After punching, the corks are coated with a mixture of fine cork particles and natural latex to seal the surface of the cork and improve its performance as a wine stopper.