The Mycobiota of Speck, a Traditional Tyrolean Smoked and Cured Ham
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1399 Journal of Food Protection, Vol. 63, No. 10, 2000, Pages 1399±1403 Copyright Q, International Association for Food Protection The Mycobiota of Speck, a Traditional Tyrolean Smoked and Cured Ham URSULA PEINTNER, JOHANNES GEIGER, AND REINHOLD POÈ DER* Institute of Microbiology, Leopold-Franzens-University Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria MS 99-383: Received 22 December 1999/Accepted 20 May 2000 ABSTRACT Downloaded from http://meridian.allenpress.com/jfp/article-pdf/63/10/1399/1685977/0362-028x-63_10_1399.pdf by guest on 27 September 2021 Speck is a ham specialty product traditionally produced in South Tyrol (Italy) and North Tyrol (Austria) by farmers, butcheries, and meat industries. To date, nothing has been learned about fungi associated with this smoked and cured meat. Therefore, it was the main objective of this study to assess the typical mycobiota of Speck in relation to the different production types and the geographic provenance. A total of 121 Speck samples from North Tyrol and South Tyrol was analyzed. From 63 isolated fungal species, only a few can be regarded as typical colonizers: Eurotium rubrum and Penicillium solitum were the dominating species in all types and parts of Speck (crust, meat, and fat). Eight other Penicillium spp. were relatively frequent. The species diversity increased from industrially produced Speck to products from butcheries and farmers, and it was higher in all types of South Tyrolean products. Among the typical mycobiota, Penicillium verrucosum, Penicillium canescens, and Penicillium commune are known as potentially mycotoxigenic. Speck is a smoked and cured meat specialty product known about the fungi associated with this special smoked produced in alpine regions for centuries, especially in South and cured meat product. An investigation of the molds Tyrol (Italy) and North Tyrol (Austria), using the same ba- growing on Speck is also important, because this traditional sic method. Pork is brined with curing salts and left in the Tyrolean product is produced not only by farmers but, due resulting pickling solution for about 3 to 4 weeks at 88C. to increasing demand, also by butcheries and meat indus- Then the meat is periodically cold smoked with wood tries. Thus, Speck has become widely available in European smoke at a temperature of about 208C for 6 to 8 weeks. supermarkets and specialty stores in recent years. No Eu- The frequency and the respective duration of smoking dur- ropean Union standards exist regarding the fungal species ing this period vary strongly. After this, the Speck is rip- composition and the colonization rates of Speck, nor do ened in well-ventilated ripening chambers at 10 to 158C for such standards exist in Austria or Italy, which are the main an average of 3 to 6 months. Speck-producing countries. However, directives regarding The technology of smoking and curing is used not only the production and quality of Speck have been established: as a preservation method, which prevents microbiological in Austria (North Tyrol and East Tyrol), Speck has to be spoilage through a combined salting-smoking-drying pro- produced following the general Austrian directives for salt cess, but also for the organoleptic qualities it confers to the meat (3). In Italy, the trademark South Tyrolean Speck meat. The availability of unbound water (water activity or (SuÈdtiroler Speck or Speck dell' Alto Adige) is marked aw), which is reduced in cured meat products, allows the with a protected logo and may be distributed only if strict growth of a limited number of competitive microorganisms, production guidelines and quality prescriptions are followed particularly in molds. The colonization of Speck occurs by the manufacturers (4). In both countries, the quality con- spontaneously by the mycobiota of the production environ- trol is mainly based on sensory testing, physicochemical ment or by contamination with spices (9). Also, the com- parameters (moisture, chlorides, nitrates, nitrites, pH), and panies that produce Speck on an industrial scale do not use classic hygienic parameters concerning bacteria, yeasts, starter cultures but rely on the indigenous mycobiota to mites, and parasites. Because of the lack of information carry out a spontaneous fermentation, because fungal concerning molds on and in Speck, no quality standards growth is appreciated for its bene®cial effects on ¯avor. regarding these organisms exist. Molds growing on the surface of meat products have li- Therefore, the objective of the present study was to polytic activities and, therefore, play a role in determining identify and characterize the typical mycobiota of Speck. the ¯avor and aroma of the product (21). However, these molds are potentially mycotoxigenic. The composition and A species-speci®c identi®cation of the fungi growing on development of the mycobiota of meat products, in general, this meat specialty product is important, because some usually depend on the nature of the product, processing mold species are known to produce mycotoxins in meat time, and ripening conditions (1). Up to now, nothing is products and may, thereby, represent a health hazard (1).A further aim was to compare the impact of the three different * Author for correspondence. Tel: 143-(0)512-507-6002; Fax: 143- production types (products made by farmers, butcheries, (0)512-507-2938; E-mail: [email protected]. and meat industries) and the geographic provenance (South 1400 PEINTNER ET AL. J. Food Prot., Vol. 63, No. 10 TABLE 1. Water activity (aw), average colonization rate, and percentage of Speck samples with fungal growth in fat and/or meat for the six types of Speck produced by industries, butcheries, and farmers in North Tyrol (Austria) and South Tyrol (Italy) Fat and/or meat sam- aw Colonization (%) ples with fungal Type of Speck n Fat Meat Fat Meat growth (%) Industrial, Italy 15 0.86 6 0.04 Aa 0.89 6 0.02 A 33 6 32 AB 16 6 21 A 80 Industrial, Austria 15 0.86 6 0.03 A 0.89 6 0.02 A 20 6 24 A 24 6 28 AB 93 Butcheries, Italy 15 0.86 6 0.05 A 0.89 6 0.02 A 44 6 43 B 36 6 34 B 67 Butcheries, Austria 15 0.84 6 0.03 AB 0.89 6 0.03 AB 43 6 37 B 32 6 35 B 80 Farmers, Italy 31 0.83 6 0.08 BD 0.86 6 0.07 B 47 6 42 B 44 6 39 B 81 Farmers, Austria 30 0.78 6 0.11 CD 0.85 6 0.08 B 20 6 29 A 18 6 29 A 73 Downloaded from http://meridian.allenpress.com/jfp/article-pdf/63/10/1399/1685977/0362-028x-63_10_1399.pdf by guest on 27 September 2021 a Means in the column with different letters are signi®cantly different (P , 0.05). Tyrol and North Tyrol) on fungal species composition and media were used for species identi®cation: Czapek yeast extract the extent of fungal colonization. agar, Czapek yeast extract agar with 20% sucrose, 25% glycerol nitrate agar, creatine sucrose neutral agar, oat agar, and synthetic MATERIALS AND METHODS nutrient agar. For formulations of the media see Klich and Pitt (10), Pitt (17), and Pitt and Hocking (18). The isolates were usu- Sampling. A total of 121 samples (60 from North Tyrol, ally incubated at 258C for 7 days. Some molds (e.g., Fusarium Austria, and 61 from South Tyrol, Italy) were analyzed: 30/31 spp., Mycelia sterilia) were incubated for longer periods under produced by farmers, 15/15 from butcheries, and 15/15 from meat periodical changes of daylight and black light (360 nm; 12/12 h). industries. The samples were purchased as whole pieces of Speck (minimal size, 4 by 4 cm) in supermarkets, in stores, or directly Identi®cation of molds. As far as possible, all isolates were from the farmers. It was not possible to get Speck samples from identi®ed to species level using relevant taxonomical keys (6±8, exactly the same stages of ripening. However, all products were 10, 16±20, 23, 25). The nomenclature follows Pitt and Hocking sold as unspoiled products suitable for consumption. The indus- (18). Yeasts were not considered in this study. trial products were vacuum wrapped, and the other Speck samples were traditionally wrapped in paper (mostly plasticized paper). All Water activity (aw). The aw was measured at room temper- samples were photographed. Furthermore, the diameters of the fat ature by a thermohydrometer, Hygroskop DT (Rotronic AG, Zu- and meat parts were measured. As far as possible, all criteria con- rich, Switzerland) with a humidity sensor DMS 100 H (accuracy: 6 sidered in this study were investigated separately for the meat part, 2%) calibrated with saturated salt solutions. fat part, and crust (surface) of the Speck. After sampling, the Statistical analysis. The results were analyzed statistically 2 8 remaining part of the Speck was deep frozen at 20 C for future using Statistica (Statsoft Inc., version 5, 1997). Data were ana- physicochemical and toxicological investigations. lyzed with one-way analysis of variance. Separation of means was , Microbiological assays. Molds were isolated from the sur- tested by the Tukey honestly signi®cant difference test (P 0.05). face of the Speck samples by contact plating a piece of crust (3 RESULTS AND DISCUSSION by 2 cm) onto DG18 (Oxoid) agar plates (three replicates). For isolation of molds from within Speck, a thin surface layer of the The aw of Speck. The aw of the fat and meat parts original cutting face of the Speck sample was aseptically removed differed signi®cantly. In general, meat had an aw of 0.85 to using a sterile, specially constructed bent razor blade on a handle. 0.89, and fat had an aw of 0.78 to 0.86 (Table 1).