Functional characterization of biodegradable films obtained from whole Paecilomyces variotii biomass.

The indiscriminate use of petroleum-based polymers and plastics for single-use food packaging has led to serious environmental problems due the non-biodegradable characteristics. Thus, much attention has been focused on the research of new biobased and biodegradable materials. Yeast and fungal biomass are low-cost and abundant sources of biopolymers with highly promising properties for the development of biodegradable materials. This study aimed to select a preparation method to develop new biodegradable films using the whole biomass of Paecilomyces variotii subjected to successive physical treatments including ultrasonic homogenization (US) and heat treatment. Sterilization process had an important impact on the final filmogenic dispersion and mechanical properties of the films. Longer US treatments produced a reduction in the particle size and the application of an intermediate UT treatment contributed favorably to the breaking of agglomerates allowing the second US treatment to be more effective, achieving an ordered network with a more uniform distribution. Samples that were not filtrated after the sterilization process presented mechanical properties similar to plasticized materials. On the other hand, the filtration process after sterilization eliminated soluble and hydratable compounds, which produced a reduction in the hydration of the films.

Sensory analysis for stuffed cheese with Penicillium nalgiovense superficial growth.

Sensory analysis for stuffed cheese with Penicillium nalgiovense superficial growth using a descriptive analysis was performed. Cheeses were manufactured in a pilot plant. Penicillium nalgiovense was superficially inoculated and the cheeses were ripened at 12 °C and 90% relative humidity until packaged using a microperforated polyethylene film on day 14. The ripening process continued at either 5 °C or 12 °C for 21 days. Results showed that P. nalgiovense not only confers the external desirable appearance but also has a protective effect against dehydration process. Inoculated cheeses showed descriptors of odour and flavour associated with moulds. Ammonia notes were perceived only for inoculated cheeses on day 35 being more pronounced at 12 °C than 5 °C. The high fat content of the cheeses and the transparent and microperforated packaging might affect the oxidative stability of cheeses at the end of the ripening.

Surface mycobiota of home-made dry cured sausages from the main producing regions of Argentina and morphological and biochemical characterization of Penicillium nalgiovense populations.

The characteristics and quality of home-made dry cured sausages can be recognized and associated with the region of origin. The characteristics of this type of sausages result from the superficial mycobiota that spontaneously colonizes the products. The aim of this study was to identify the house mycobiota associated with home-made dry cured sausages from different localities of Argentina and characterize the populations of Penicillium nalgiovense present by morphological and biochemical markers. To this end, 79 samples were collected from 10 localities of three main producing regions (Buenos Aires, Córdoba and La Pampa provinces). A total of 196 isolates belonging to six genera and 17 species were obtained. The predominant genus was Penicillium (134 of the isolates) and the predominant species was P. nalgiovense (108 isolates). The isoenzyme patterns of α-esterase (α-EST; EC 3.1.1.1) and Malate dehydrogenase NADP+(MDHP; EC 1.1.1.40) were characterized in 48 of these isolates (ten from Colonia Caroya, ten from Oncativo, ten from Tandil, nine from Mercedes and nine from La Pampa). A total of 26 bands were observed: 17 for α-EST and 9 for MDHP. α-EST was the most polymorphic isoenzyme, whereas MDPH presented no polymorphism. The results were subjected to numerical analysis. Cluster analysis revealed the formation of two groups: Group I formed by 24 isolates from Córdoba and Buenos Aires provinces and Group II with 24 isolates from La Pampa and Buenos Aires province. These data suggest the existence of morphological and biochemical variations among P. nalgiovense populations with different geographical origin.

Microbiological and Sensory Characteristics of Mould-Ripened Salami under Different Packaging Conditions.

The preservation of mould-ripened salami was investigated during 48 days at 19-20 °C under different packaging conditions: (i) high barrier film filled with air, 100% N2 or under vacuum, (ii) biaxially oriented polypropylene film, (iii) microperforated polyethylene film and (iv) unpackaged. Sensory, texture profile, physicochemical and microbiological analyses were performed. Fungal quantification revealed two data groups. In group 1 (consisting of salami in microperforated polyethylene film, biaxially oriented polypropylene film and unpackaged) the conidium viability was relatively constant. In group 2 (salami preserved in high barrier film filled with air, 100% N2 or under vacuum) the conidium viability decreased due to the absence of oxygen and the high carbon dioxide volume fraction. SEM micrographs showed micromorphological changes in fungal structure; microperforated polyethylene film, biaxially oriented polypropylene film and unpackaged conditions preserved the conidial morphology, while high barrier film filled with air, 100% N2 or vacuum conditions collapsed the hyphae and most of the conidia. Salami packed in microperforated polyethylene film and biaxially oriented polypropylene film showed the most acceptable organoleptic characteristics and lower hardness and chewiness values after packaging.

Indigenous filamentous fungi on the surface of Argentinean dry fermented sausages produced in Colonia Caroya (Córdoba).

Some producers of dry fermented sausages use fungal starter cultures with the aim to achieve a desirable surface appearance and avoid the growth of mycotoxigenic fungi. These commercial cultures are mainly composed of Penicillium nalgiovense biotype 6. In contrast, in the case of producers who do not use starters, sausages are spontaneously colonized by the house mycobiota, which generally consists of heterogeneous molds corresponding to different genera and species. In this work, the surface mycobiota of dry fermented sausages produced in Colonia Caroya (Córdoba, Argentina) was determined in both summer and winter seasons. All the sausages sampled had been made without the use of surface fungal starters. In the 57 sausages analyzed in the two winter seasons studied (2010 and 2012), we found a total of 95 isolates of filamentous fungi belonging to six genera (Penicillium, Aspergillus, Mucor, Cladosporium, Scopulariopsis and Eurotium) and ten fungal species, whereas in the 36 sausages analyzed in the two summer seasons studied (2011 and 2012), we found 89 isolates belonging to five genera (Penicillium, Aspergillus, Mucor, Cladosporium and Geotrichum) and ten fungal species. Although 16 different species were found in both winter and summer seasons, only 2 of them predominated completely. P. nalgiovense was found in almost 100% of the sausages analyzed, where biotype 4 was the most frequent. This species gives a whitish gray coloration to the sausages. Considering that the factories sampled do not use fungal starter cultures, this predominance is very interesting since mycotoxin production by this fungus has not been reported. Aspergillus ochraceus was isolated with a frequency of 80-90% in the summer seasons, but in none of the winter samples. The presence of this fungus in sausages produced in the summer was attributed to the high environmental temperatures and the uncontrolled temperature in the ripening rooms during the night. In all cases, A. ochraceus was responsible for the undesirable yellowish gold color of the casing. This fungus thus causes significant economic losses to the producers of Colonia Caroya during the months of high temperatures.

Mycoflora and natural incidence of selected mycotoxins in rabbit and Chinchilla feeds.

Mycotoxins are secondary metabolites produced by filamentous fungi that cause a toxic response when ingested by animals or man. Demand of natural fur, such as those from rabbit and chinchilla, produced under controlled conditions, has increased worldwide. The toxicogenic mycoflora contaminating feeds for these animals was enumerated and identified. Six of the major mycotoxins implicated in animal mycotoxicosis were detected and quantified. Moulds count ranged from <10 to 4.7 × 10(5) CFU g(-1); 14% of the samples exceeded the limit that determines hygienic feed quality. More than twenty species belonging to the five most important mycotoxigenic mould genera were recovered. Among the analyzed mycotoxins, aflatoxins were recovered in 100% of the examined samples, deoxynivalenol in 95%, fumonisins in 100%, ochratoxin A in 98%, T2 toxin in 98%, and zearalenone in 100%. Cooccurrence of mycotoxins was observed in 100% of the samples analyzed. Exposure to multiple mycotoxins was thus demonstrated for these animals.

Fungal diversity and natural occurrence of fusaproliferin, beauvericin, deoxynivalenol and nivalenol in wheat cultivated in Santa Fe Province, Argentina.

The Fusarium diversity and the mycobiota associated with moldy wheat kernels from Santa Fe province, Argentine, was assessed. The wheat cultivated area in Santa Fe province is divided according to agrometeorological conditions into two zones: Zone I (north-central) and Zone II (south). The natural occurrence of Fusarium toxins BEA, FUP, DON and NIV was also determined. Cladosporium was the most abundant of the 19 genera identified, followed by Fusarium, Phoma and Alternaria. Zone II shows a predominance of F. graminearum and F. culmorum. In Zone I, DON was present in 13/32 samples (range 0.43-3.60 mg kg(-1)) and NIV in 6/32 samples (range 0.11-0.40 mg kg(-1)). In zone II, DON was found in 11/21 samples (range 0.57-9.50 mg kg(-1)) and NIV in 4/21 samples (range 0.10-0.60 mg kg(-1)). BEA and FP were not detected in both zones.

Toxicological assessment of Penicillium nalgiovense strains for use as starter cultures in the manufacture of dry fermented sausages.

The use of fungal starter strains in the casing of dry fermented sausages allows standardization of the manufacturing process and ensures consumer safety. Penicillium nalgiovense is normally used for this purpose. Even though this species is reported as safe with respect to the production of the most common mycotoxins, its safety may be strain specific. The aim of the present work was to assess the toxicogenic potential of nine P. nalgiovense strains isolated from dry fermented sausages that were previously suitable as starters. The strains were tested for toxicity on brine shrimp larvae and the human cell line MCF7, for mutagenicity in the Ames test, and for antibacterial activity against gram-positive and gram-negative bacteria. According to our results, several P. nalgiovense strains were positive in more than one bioassay. Therefore, it is important to use different toxicological assays when characterizing strains intended for food use. Strains S1-2 and S14-4, which belong to biotypes 6 and 5, respectively, were nontoxigenic under the conditions tested. Overall, strain S1-2 of P. nalgiovense proved to be best suited as a starter in dry fermented sausage manufacture because in addition of being nontoxicogenic it produces white conidia, which is a desirable feature.

Determination of growth characteristics and lipolytic and proteolytic activities of Penicillium strains isolated from Argentinean salami.

The growth of Penicillium spp. on the surface of meat-based dry fermented sausages provides them with a protective effect against some undesirable microorganisms. Penicillium also acts as an antioxidant, minimizes the risk of excessive drying, and it is responsible for flavor development due to the decomposition of proteins, free fatty acids and lactic acid. With the aim of developing starter cultures, important physiological properties such as growth and proteolytic and lipolytic activities were evaluated on 13 mold strains belonging to the genera Penicillium. These strains were isolated from Argentinean dry fermented meat sausages named "salami". The selection was based on color, mycellium appearance and growth characteristics. The most important factors of the drying process of salami, such as temperature (14 and 25 degrees C), water activity (aw) (0.90, 0.95 and 1.00) and presence of 2.5% sodium chloride (NaCl), were analyzed. Although all strains analyzed were able to grow under the different conditions evaluated, they showed different growth velocity (K = mm/day) in response to temperature, aw and presence of NaCl in the media. All strains showed both proteolytic and lipolytic activities under the studied factors of the drying process. Nevertheless, differences in inter-species and even intra-species were found. The addition of NaCl gave a stimulant effect to the proteolytic activity at 25 degrees C, but the response at 14 degrees C was variable. The same variability was observed in the presence of salt, both at 25 and 14 degrees C, when the lipolytic activity was assayed. According to our results, detailed assays of the physiological capacities of indigenous strains proposed as starter cultures are required.