-The possibility of producing a fermented beverage from donkey's milk using the probiotic bacterial strains Lactobacillus rhamnosus AT 194, CLT 2/2, and Lactobacillus casei LC 88, isolated from Parmigiano Reggiano cheese was investigated. The chemical-physical and microbiological properties of the raw milk demonstrated that it has a low microbiological load and an elevated content of lysozyme. The bacterial strains employed for fermentation had a good growth capacity in donkey's milk only after an initial adaptation phase. An extremely high percentage of viable bacteria were found in the final beverage, even after a 30-day shelf life. Likewise, the activity of lysozyme was virtually unchanged with respect to initial values. Sensorial analysis permitted the individuation of differences between the three bacterial strains used for fermentation in terms of descriptors relative to aromatic-olfactory qualities. Based on the above results, technology can be proposed for production of a fermented beverage from donkey's milk that can be utilized by small producers. This would allow the production of a beverage that would be well accepted by consumers interested in a product with favorable therapeutic properties integrated with probiotic bacteria. CLT 2/2 et la souche Lactobacillus casei LC 88 toutes isolées du fromage Parmigiano Reggiano. Le lait, caractérisé du point de vue physico-chimique et microbiologique, a comme caractéristiques prédominantes une charge microbienne faible et un contenu en lysozyme élevé. Les souches utilisées ont montré une bonne capacité de développement dans le lait d'ânesse seulement après une phase d'adaptation. Les bactéries inoculées sont restées vivantes plus de trente jours dans les boissons obtenues, garantissant ainsi une longue durée de conservation. Au terme de l'essai, l'activité du lysozyme n'a présenté aucune variation sensible par rapport à l'activité initiale. L'analyse sensorielle à laquelle ont été soumises les boissons fermentées a permis de discriminer les différences induites par les trois souches utilisées en ce qui concerne quelques descripteurs relatifs au tableau aromatique et olfactif. Une technologie de production d'une boisson fermentée applicable à de petits ateliers artisanaux a donc été proposée, permettant d'obtenir un produit en mesure d'être accepté par un consommateur intéressé à la fois par les caractéristiques thérapeutiques du lait d'ânesse et les propriétés bénéfiques pour la santé des bactéries probiotiques.
-The aim of this work was to gain a comprehensive view of the microbiological characteristics of milk, natural whey starter, and cheese during the first months of ageing of Parmigiano Reggiano. A significant presence of different microbial groups in raw milk from the initial moments of production was rapidly substituted by various lactic acid bacteria. Natural whey starter contained a large number of thermophilic lactic acid bacteria (Lactobacillus helveticus, L. delbrueckii ssp. lactis, L. delbrueckii ssp. bulgaricus) and some facultatively heterofermentative lactic acid bacteria belonging to L. rhamnosus. Thermophilic lactic acid bacteria disappeared within 30 d. Rod-shaped mesophilic facultatively heterofermentative lactic acid microflora, consisting of L. casei, L. paracasei ssp. paracasei, L. paracasei ssp. tolerans, L. rhamnosus and pediococci, progressively increased up to the fifth month of ageing. Results showed that thermophilic lactobacilli were derived from natural whey starter whereas Streptococcus thermophilus originated from raw milk. Further, natural whey starter was the source of L. rhamnosus which was present throughout the entire period of the cheese ageing. The other components of non-starter lactic acid microflora derived from raw milk.
The aim of this work was to study the interaction of corrugated and plastic materials with pathogenic and spoiling microorganisms frequently associated to fresh produce. The effect of the two packaging materials on the survival during the storage of microorganisms belonging to the species Escherichia coli, Listeria monocytogenes, Salmonella enteritidis, Saccharomyces cerevisiae, Lactobacillus plantarum, Pseudomonas fluorescens, and Aspergillus flavus was studied through traditional plate counting and scanning electron microscopy (SEM). The results obtained showed that cardboard materials, if correctly stored, reduced the potential of packaging to cross-contaminate food due to a faster viability loss by spoilage and pathogenic microorganisms compared to the plastic ones. In fact, the cell loads of the pathogenic species considered decreased over time independently on the inoculation level and packaging material used. However, the superficial viability losses were significantly faster in cardboard compared to plastic materials. The same behavior was observed for the spoilage microorganisms considered. The SEM microphotographs indicate that the reduction of superficial contamination on cardboard surfaces was due to the entrapping of the microbial cells within the fibers and the pores of this material. In addition, SEM data showed that the entrapped cells were subjected to more or less rapid lyses, depending on the species, due to the absence of water and nutrients, with the exception of molds. The latter spoilers were able to proliferate inside the cardboard fibers only when the absorption of water was not prevented during the storage. In conclusion, the findings of this work showed the reduction of cross-contamination potential of corrugated compared to plastic packaging materials used in fruit and vegetable sector. However, the findings outlined the importance of hygiene and low humidity during cardboard storage to prevent the mold growth on packaging.
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