Spontaneously growing fungi on the surface and processing areas of matured sheep ham and volatile compounds produced.

Raw ham is a dried and matured product traditionally made from pork leg, but other animals, such as sheep, can be used. The natural presence of bacteria and fungi in this product influences its characteristics throughout the process. This study analysed the fungal populations present during raw sheep hams' processing. Two types of products were developed: without and with the addition of seasonings. Mycological analyses were carried out from the ingredients, seasonings, facilities air, as well as on the surfaces of the hams and the air in the chamber throughout the maturation period (0, 45, 90, and 180 days) using 18 % dichloran glycerol agar and the data were submitted to Principal Component Analysis. Volatile compounds were evaluated at the end of the sheep ham manufacturing process through a gas chromatograph coupled to a mass spectrometer. At 45 days of aging, a more remarkable similarity was observed between the fungi present on the non-seasoned hams and those in the ripening chamber's air, while the seasoned hams showed a more evident relation with those fungi present in the spices. With time, the fungi in the air of the ripening chamber started to be influenced by Aspergillus ser. Aspergillus and Aspergillus ser. Rubri already installed in the seasoned hams at 45 days, and then it probably dispersed the non-seasoned ones due to the airborne spores, becoming the most prevalent in both treatments at 90 days. At the end of ripening, the mycobiota of both raw hams was composed mainly by xerophilic species of Aspergillus section Aspergillus. The total fungal count was 5.78 log CFU/cm2 for the non-seasoned and 7.19 log CFU/cm2 for the seasoned ones. A potentially ochratoxigenic Aspergillus ser. Circumdati was detected at the end of aging in raw, unseasoned hams. In conclusion, seasoning directly influences the species developing on the surface of seasoned hams throughout the ripening process, and indirectly affects the mycobiota of the non-seasoned hams when sharing the same ripening chamber. The presence of fungi in the matured sheep ham seems to contribute to the formation of volatile compounds, which are related to the sensory quality of these products.

Taxonomic Characterization and Secondary Metabolite Profiling of Aspergillus Section Aspergillus Contaminating Feeds and Feedstuffs.

Xerophilic fungal species of the genus Aspergillus are economically highly relevant due to their ability to grow on low water activity substrates causing spoilage of stored goods and animal feeds. These fungi can synthesize a variety of secondary metabolites, many of which show animal toxicity, creating a health risk for food production animals and to humans as final consumers, respectively. Animal feeds used for rabbit, chinchilla and rainbow trout production in Argentina were analysed for the presence of xerophilic Aspergillus section Aspergillus species. High isolation frequencies (>60%) were detected in all the studied rabbit and chinchilla feeds, while the rainbow trout feeds showed lower fungal charge (25%). These section Aspergillus contaminations comprised predominantly five taxa. Twenty isolates were subjected to taxonomic characterization using both ascospore SEM micromorphology and two independent DNA loci sequencing. The secondary metabolite profiles of the isolates were determined qualitatively by HPLC-MS. All the isolates produced neoechinulin A, 17 isolates were positive for cladosporin and echinulin, and 18 were positive for neoechinulin B. Physcion and preechinulin were detected in a minor proportion of the isolates. This is the first report describing the detailed species composition and the secondary metabolite profiles of Aspergillus section Aspergillus contaminating animal feeds.

Utilization of molasses and sugar cane bagasse for production of fungal invertase in solid state fermentation using Aspergillus niger GH1.

Agro-industrial wastes have been used as substrate-support in solid state fermentation for enzyme production. Molasses and sugarcane bagasse are by-products of sugar industry and can be employed as substrates for invertase production. Invertase is an important enzyme for sweeteners development. In this study, a xerophilic fungus Aspergillus niger GH1 isolated of the Mexican semi-desert, previously reported as an invertase over-producer strain was used. Molasses from Mexico and Cuba were chemically analyzed (total and reducer sugars, nitrogen and phosphorous contents); the last one was selected based on chemical composition. Fermentations were performed using virgin and hydrolyzate bagasse (treatment with concentrated sulfuric acid). Results indicated that, the enzymatic yield (5231 U/L) is higher than those reported by other A. niger strains under solid state fermentation, using hydrolyzate bagasse. The acid hydrolysis promotes availability of fermentable sugars. In addition, maximum invertase activity was detected at 24 h using low substrate concentration, which may reduce production costs. This study presents an alternative method for invertase production using a xerophilic fungus isolated from Mexican semi-desert and inexpensive substrates (molasses and sugarcane bagasse).

Utilization of molasses and sugar cane bagasse for production of fungal invertase in solid state fermentation using Aspergillus niger GH1

Agro-industrial wastes have been used as substrate-support in solid state fermentation for enzyme production. Molasses and sugarcane bagasse are by-products of sugar industry and can be employed as substrates for invertase production. Invertase is an important enzyme for sweeteners development. In this study, a xerophilic fungus Aspergillus niger GH1 isolated of the Mexican semi-desert, previously reported as an invertase over-producer strain was used. Molasses from Mexico and Cuba were chemically analyzed (total and reducer sugars, nitrogen and phosphorous contents); the last one was selected based on chemical composition. Fermentations were performed using virgin and hydrolyzate bagasse (treatment with concentrated sulfuric acid). Results indicated that, the enzymatic yield (5231 U/L) is higher than those reported by other A. niger strains under solid state fermentation, using hydrolyzate bagasse. The acid hydrolysis promotes availability of fermentable sugars. In addition, maximum invertase activity was detected at 24 h using low substrate concentration, which may reduce production costs. This study presents an alternative method for invertase production using a xerophilic fungus isolated from Mexican semi-desert and inexpensive substrates (molasses and sugarcane bagasse).

Utilization of molasses and sugar cane bagasse for production of fungal invertase in solid state fermentation using Aspergillus niger GH1

Agro-industrial wastes have been used as substrate-support in solid state fermentation for enzyme production. Molasses and sugarcane bagasse are by-products of sugar industry and can be employed as substrates for invertase production. Invertase is an important enzyme for sweeteners development. In this study, a xerophilic fungus Aspergillus niger GH1 isolated of the Mexican semi-desert, previously reported as an invertase over-producer strain was used. Molasses from Mexico and Cuba were chemically analyzed (total and reducer sugars, nitrogen and phosphorous contents); the last one was selected based on chemical composition. Fermentations were performed using virgin and hydrolyzate bagasse (treatment with concentrated sulfuric acid). Results indicated that, the enzymatic yield (5231 U/L) is higher than those reported by other A. niger strains under solid state fermentation, using hydrolyzate bagasse. The acid hydrolysis promotes availability of fermentable sugars. In addition, maximum invertase activity was detected at 24 h using low substrate concentration, which may reduce production costs. This study presents an alternative method for invertase production using a xerophilic fungus isolated from Mexican semi-desert and inexpensive substrates (molasses and sugarcane bagasse).

Efeito da adição de dicloran ao diluente, para enumeração de fungos em alimentos desidratados utilizando-se o sistema petrifilm para bolores e leveduras / Effect of the addition of dicloran to the diluent, for enumeration of fungi in sustenances dehydrated utilizing itself the system petrifilm for fungi and yeasts

A contagem de bolores e leveduras nos alimentos é indicativa de falhas higiênicas ao longo do processamento ou matérias-primas de má qualidade. Nos alimentos desidratados, os fungos xerofílicos representam os principais microrganismos responsáveis de multiplicação. Diversas técnicas e meios de cultura tem sido utilizados para a sua enumeração para alimentos com baixa atividade de água. Dez amostras de diferentes alimentos foram divididas em 5 subamostras cada, totalizando 50 amostras. Os seguintes tratamentos foram avaliados: Petrifilm (controle), Petrifilm (com dicloran) e DG-18 (controle). Os resultados da análise estatística permitem concluir que não há diferença significativa, ao nível de 5 por cento, entre os tratamentos avaliados. A ocorrência de colônias espalhadas parece não estar associada a um tipo de alimento, mas às amostras de um determinado alimento. Ao se usar altas diluições, as colônias espalhadas não estiveram comumente presentes, não afetando, portanto, a contagem no Petrifilm Bolores e Leveduras.(AU)

The yeast and mold enumeration of foods is indicative of poor hygienical conditions in the processing or raw materials of bad quality. In dehydrated foods, the xerophilic fungi are the major responsible of deterioration. Several techniques and culture media have been used for its enumeration, being agar DG-18 recommended for foods with low water activity. Ten differents food samples were divided into five subsamples, totalizing 50 samples. The following treatments were evaluaied: PetrifiIm (control), PetrifiIm (with dicloran) and DG-18 (control). The results of the statistical analysis allow to conclude that it does not have significant difference to the 5% level between the evaluated treatments. The occurrence of spread colonies, seems not to be associated to a type of food, but with samples of one determined food. When high dilutions were used, spread colonies weren't present, not affecting, therefore, the Petrifilm Yeast and Mold counts. (AU)

Efeito da adição de dicloran ao diluente, para enumeração de fungos em alimentos desidratados utilizando-se o sistema petrifilm para bolores e leveduras / Effect of the addition of dicloran to the diluent, for enumeration of fungi in sustenances dehydrated utilizing itself the system petrifilm for fungi and yeasts

A contagem de bolores e leveduras nos alimentos é indicativa de falhas higiênicas ao longo do processamento ou matérias-primas de má qualidade. Nos alimentos desidratados, os fungos xerofílicos representam os principais microrganismos responsáveis de multiplicação. Diversas técnicas e meios de cultura tem sido utilizados para a sua enumeração para alimentos com baixa atividade de água. Dez amostras de diferentes alimentos foram divididas em 5 subamostras cada, totalizando 50 amostras. Os seguintes tratamentos foram avaliados: Petrifilm (controle), Petrifilm (com dicloran) e DG-18 (controle). Os resultados da análise estatística permitem concluir que não há diferença significativa, ao nível de 5 por cento, entre os tratamentos avaliados. A ocorrência de colônias espalhadas parece não estar associada a um tipo de alimento, mas às amostras de um determinado alimento. Ao se usar altas diluições, as colônias espalhadas não estiveram comumente presentes, não afetando, portanto, a contagem no Petrifilm Bolores e Leveduras.

The yeast and mold enumeration of foods is indicative of poor hygienical conditions in the processing or raw materials of bad quality. In dehydrated foods, the xerophilic fungi are the major responsible of deterioration. Several techniques and culture media have been used for its enumeration, being agar DG-18 recommended for foods with low water activity. Ten differents food samples were divided into five subsamples, totalizing 50 samples. The following treatments were evaluaied: PetrifiIm (control), PetrifiIm (with dicloran) and DG-18 (control). The results of the statistical analysis allow to conclude that it does not have significant difference to the 5% level between the evaluated treatments. The occurrence of spread colonies, seems not to be associated to a type of food, but with samples of one determined food. When high dilutions were used, spread colonies weren't present, not affecting, therefore, the Petrifilm Yeast and Mold counts.