-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.

Parmigiano Reggiano is a hard, cooked cheese produced in specific areas of Northern Italy. The raw material is obtained by mixing the partly skimmed evening milk and whole morning milk. The mixture is then heated to 22°C, and natural whey starter is added at 28–30 g/l after 1–2 min, bringing the pH of the mixture to 6·2–6·3. After coagulation, which takes ∼15 min and occurs at 32–33°C owing to the addition of calf rennet powder, the curd is broken up for 2–4 min, cut into fragments and cooked at a temperature raised gradually to 42–44°C and then more quickly to 55–56°C over 10–15 min. The curd is left undisturbed, covered by the whey, for 40–60 min, then removed and placed inside a circular wooden mould. The cheese is held at ∼20°C for 3 d during which it is turned at frequent intervals to facilitate complete whey drainage. The cheese, which now has its typical shape and size, is then salted by immersion in brine (260–280 g NaCl/l at 16–17°C) for 20–24 d. During this period the cheese absorbs 15–18 g NaCl/kg and its weight decreases by 4%. During the subsequent period of ripening (12–24 months) in store rooms at 16–18°C and 85% moisture, the cheese is frequently turned. At the end of ripening the cheese is cylindrical in shape, with a slightly convex side, 0·22–0·24 m high, 0·40–0·45 m diam. weighs 35–36 kg, has 320–330 g fat/kg dry matter and a minutely granulated internal structure with small holes formed by the activity of some heterofermentative lactic acid bacteria.

Some endodontic sealers have been shown to cause local and systemic effects, mainly due to microleakage of chemicals from the sealer. To avoid the risk of toxic effects in vivo, the biological compatibility of filling materials has to be assessed. In vitro compatibility of Proroot MTA cement in comparison with two different fillers used in clinical practice, was examined by testing the adherence, viability, proliferation and secretion of collagen of osteoblast-like cells. In our experimental system, Saos-2 cells challenged with Proroot MTA for 24 and 72 h showed a better behaviour than the cells exposed to the other compounds under assay. We found that the cells attached to the rough surface of Proroot MTA cement and spread onto the rough surface. Moreover, the cells on Proroot MTA were viable, grew, and released some collagen even at 72 h, while cell metabolism and growth was dramatically reduced onto sEBA and amalgam surfaces. A parallel behaviour was found after the cells were challenged with extracts of the different fillers. In conclusion, according to our in vitro study, Proroot MTA showed a good interaction with bone-forming cells: such behaviour may partially account for its satisfying clinical performance.

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