J. J. Figueiredo Marques

Cork taint in wine : Scientific knowledge and public perception : A critical review

The manufacturing process of cork stoppers includes a stabilization period of the cork slabs, following boiling, during which mold growth completely covers the cork slabs. This process has been used traditionally for several decades; however, due to the possibility of certain molds isolated from cork to produce off flavor compounds, especially 2,4,6-trichloroanisole and 2,3,4,6-tetrachloroanisole, recently cork stoppers are being unsoundly targeted with the accusation of inducing cork taint in wine. This article reviews the manufacturing process of cork stoppers, the diversity of microorganisms associated with cork, and finally the diversity and origins of the compounds associated with cork taint in wine, focusing on those currently considered as more important. Some important results recendy obtained by the authors are also included. The current idea of suppressing mold growth during cork stopper manufacturing is discussed, as well as the erroneous idea of imputing, direcdy and exclusively, to cork the responsibility of the so-called cork taint in wine.

Mycobiota in Portuguese 'normal' and 'green' cork throughout the manufacturing process of stoppers

The compounds responsible for the so‐called ‘cork taint’ include, among others, some microbial metabolites which can be produced by the microbial population colonizing the unprocessed cork and stoppers. This study was intended to obtain information on the mycobiota associated with Portuguese cork throughout the manufacturing process of stoppers. Samples of barks and stoppers of both ‘normal’ and ‘green’ cork were examined. Moulds were isolated from ‘normal’ and ‘green’ cork throughout the entire cork stopper manufacturing process. Yeasts were rarely detected in the corks. Fungal contamination was not detected in finished stoppers from the company under study.

Role of Chrysonilia sitophila in the quality of cork stoppers for sealing wine bottles.

The contribution of Chrysonilia sitophila in cork stopper manufacture was studied and a simulation of the industrial processing of cork stoppers was performed. Stoppers cut from slabs where mold development was inhibited were compared with others cut from slabs colonized by C. sitophila alone or with several molds, in terms of physical properties and chemical taints. C. sitophila does not produce 2,4,6-trichloroanisole, guaiacol, or 1-octene-3-ol on cork slabs incubated for 66 days. Since some chlorophenol-related compounds contaminate cork slabs during the production processes, metabolic tests were performed to investigate the capability of molds to produce 2,4,6-trichloroanisole by methylation of 2,4,6-trichlorophenol. Degradation of 2,4,6-trichlorophenol by C. sitophila resulted in a very high level of degradation without production of 2,4,6-trichloroanisole. C. sitophila restricted growth of other molds on maturing slabs for at least 30 days. These results show that C. sitophila can be exploited by industrial producers of cork stoppers since it is able to inhibit the development of other molds and it does not produce the compounds responsible for ‘cork-taint’, even in the presence of chlorophenols. Journal of Industrial Microbiology & Biotechnology (2000) 24, 256–261.

Cork stoppers industry: defining appropriate mould colonization

AIMS The main aims of this work were the study of cork slabs moulds colonization and the evaluation of the moulds diversity during cork processing steps, in different cork stoppers factories. Simultaneously, it was envisaged to perform an evaluation of the air quality. METHODS AND RESULTS Moulds were isolated and identified from cork slabs and cork samples in four cork stoppers factories. The identification was based on morphological characters and microscopic observation of the reproductive structures. Airborne spore dispersion was assessed using a two stage Andersen sampler. It was observed that Chrysonilia sitophila was always present on cork slabs during the maturing period, but mould diversity appeared to be associated to the different factory configurations and processing steps. CONCLUSIONS Spatial separation of the different steps of the process, including physical separation of the maturation step, is essential to guarantee high air quality and appropriate cork slabs colonization, i.e. C. sitophila dominance. The sorting and cutting of the edges of cork slabs after boiling and before the maturing step is also recommended. SIGNIFICANCE AND IMPACT OF THE STUDY This study is very important for the cork stopper industry as it gives clear indications on how to keep high quality manufacturing standards and how to avoid occupational health problems.