The occurrence of late blowing defects in cheese produces negative effects on the quality and commercial value of the product. In this work, we verified whether the addition of raw jenny milk to bulk cow milk reduced the late blowing defects in semihard cheeses. During cheesemaking, different aliquots of jenny milk were poured into 2 groups of 4 vats, each containing a fixed amount of cow milk. A group of cheeses was created by deliberately contaminating the 4 vats with approximately 3 log10 cfu/mL milk of Clostridium tyrobutyricum CLST01. The other 4 vats, which were not contaminated, were used for a second group of cheeses. After 120 d of ripening, some physical, chemical, and microbiological parameters were evaluated on the obtained semihard cheeses. Differences in sensory properties among cheeses belonging to the uncontaminated group were evaluated by 80 regular consumers of cheese. Our results showed that the increasing addition of jenny milk to cow milk led to a reduction of pH and total bacterial count in both cheese groups, as well as C. tyrobutyricum spores that either grew naturally or artificially inoculated. We observed a progressive reduction of the occurrence of late blowing defects in cheese as consequence of the increasing addition of jenny milk during cheese making. Moreover, the addition of jenny milk did not affect the acceptability of the product, as consumers found no difference among cheeses concerning sensorial aspects. In conclusion, the important antimicrobial activity of lysozyme contained in jenny milk has been confirmed in the current research. It is recommend for use as a possible and viable alternative to egg lysozyme for controlling late blowing defects in cheese.
Thermal treatments are used to improve milk microbial safety, shelf life, and biological activity of some of its components. However, thermal treatments can reduce the nutritional quality of milk, affecting the molecular structure of milk proteins, such as lysozyme, which is a very important milk component due to its antimicrobial effect against gram-positive bacteria. Jenny milk is characterized by high lysozyme content. For this reason, in the last few years, it has been used as an antimicrobial additive in dairy products as an alternative to hen egg white lysozyme, which can cause allergic reactions. This study aimed to investigate the effect of pasteurization and condensation on the concentration and antimicrobial activity of lysozyme in jenny milk. Furthermore, lysozyme quantity and activity were tested in raw and pasteurized milk after condensation at 40 and 20% of the initial volume. Reversed-phase HPLC was performed under fluorescence detection to monitor lysozyme in milk samples. We evaluated the antimicrobial activity of the tested milk against Bacillus megaterium, Bacillus mojavensis, Clavibacter michiganensis, Clostridium tyrobutyricum, Xanthomonas campestris, and Escherichia coli. Condensation and pasteurization did not affect the concentration or antimicrobial activity of lysozyme in jenny milk, except for B. mojaventis, which showed resistance to lysozyme in milk samples subjected to heat treatments. Moreover, lysozyme in jenny milk showed antimicrobial activity similar to synthetic antibiotics versus some gram-positive strains and also versus the gram-negative strain X. campestris.
Late blowing on semihard and hard cheese may have an important economic effect on dairy production. Many studies have attempted to prevent this defect by physical treatment, the use of additives, and the use of bacteriocins. In this paper, we look at the effect of jenny milk as an inhibitor of blowing caused by clostridia and coliforms in ewe cheese making. Bulk ewe and jenny milk samples were collected in the morning by mechanical milking and were refrigerated at 4°C. On the collected samples, the count of somatic cells, coliforms, Clostridium butyricum, and Escherichia coli were determined. The bulk raw milk was divided in two 45-L vats: vat 1 was used as a control, whereas 0.5L of jenny milk was added to vat 2. Four semihard cheeses, weighing about 2 kg each, were made from each vat. Cheese making was replicated twice. After a ripening period of 60 d, the count of coliforms and of C. butyricum was determined. In the treated group, a significant inhibition of coliform bacteria was observed. The addition of jenny milk in cheese making may prove to be a useful and innovative approach for the inhibition of spore-forming clostridia strains.
In this study, we examined the annual diet composition\ud of Lepus corsicanus in two different sites within a\ud southern Italy Regional Park. Vegetation of site 1 was composed\ud of a mixed scrub forest (Viburno–Quercetum ilicis s.l.),\ud a ripisilva (Roso sempervirentis–Populetum nigrae), some\ud thermophilous scrubs (Pruno–Rhamnetalia alaterni), and a\ud Pinus halepensis reforested area. Site 2 comprised a mixedoak\ud forest (Centaureo–Quercetum pubescentis s.l.) with\ud meadows and arable lands. Micro-histological analysis of\ud faecal samples revealed that hares utilised 70 different species\ud of plants during the year, indicating the capability of the\ud Apennine hare of exploiting a wide variety of vegetation.\ud Herbaceous plants (Hemicryptophytes, particularly graminoid\ud grasses, and Geophytes) predominated in the diet.\ud Brachypodium sylvaticum (9.44 %) and Allium subhirsutum\ud (8.28 %) were the major contributors to the diet in sites 2 and\ud 1, respectively. Other taxa found most often in the diet were\ud Trifolium pratense (site 1: 8.19 %; site 2: 5.80 %) and Prunus\ud spinosa (site 1: 7.03 %; site 2: 4.10 %). Significant differences\ud were found between sites in terms of diet richness, diversity,\ud and evenness. Nevertheless, both the similarity indices\ud (Morisita–Horn: 0.79; Sørensen: 0.87) showed that the food\ud composition of the hare’s diet was broadly the same in both\ud sites. Some qualitative and quantitative differences between\ud sites were due to the availability or consumption of some plant\ud species and evidenced that the Apennine hare can modify its\ud trophic niche in order to adapt its dietary requirements to the\ud availability of food
The addition of jenny milk during cheesemaking has been recommended as a viable alternative to egg lysozyme for controlling late blowing defects. However, little is known on the sensory properties of the cheeses made with jenny milk. In this study, the effect of the addition of jenny milk during cheesemaking on sensory properties and consumer acceptability of cheese was evaluated. A sensory profile was carried out by 10 trained panelists on 4 cow milk cheese types. Two types of cheeses were made by adding jenny milk to cow milk during cheesemaking; the cheeses were then left to ripen for 45 and 120 d. The remaining 2 cheese types were made with only cow milk and were also left to ripen for 45 and 120 d. The attributes generated by a quantitative descriptive analysis sensory panel were effective for discriminating the 4 products. Among them, added jenny milk samples aged for 45 d had the highest intensity of some appearance descriptors (structure and color uniformity), as well as the highest intensity of sweetness. The analysis of acceptability data obtained from 89 consumers showed that added jenny milk aged for 45 d was the most preferred type of cheese, whereas no significant differences were found among the other products, which had higher intensity of bitter, salty, acid milk, and so on.
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