2. Universidad Cardenal Herrera-CEU

The use of human milk in milk banks requires thermal processing to eliminate microbiological hazards. An evaluation is made of the stability of overall human milk bactericidal capacity following 2 modalities of thermal pasteurization: 63°C/30 minutes and 75°C/15 seconds. Ten milk samples (mature milk) were analyzed. In each sample, the effect of both thermal treatments on bactericidal capacity against Escherichia coli was evaluated in relation to the capacity of fresh milk (control). All the samples analyzed possessed bactericidal capacity. Human milk pasteurization induced a significant loss of this capacity that was more pronounced after high-temperature treatment than after low-temperature processing. Untreated milk, low-pasteurized milk, and high-pasteurized milk yielded a reduction in E. coli growth of 70.10%, 52.27%, and 36.39%, respectively. In conclusion, human milk possesses antimicrobial activity that is lost in part as a result of thermal processing. Such bactericidal capacity is, moreover, better preserved by low-temperature, long-time pasteurization.

The individual and combined antilisterial efficiency of nisin, lactic acid and modified atmosphere packaging (MAP) was investigated. Raw ground pork was inoculated with a strain of Listeria monocytogenes and samples were distributed into twelve lots. Half of the lots were stored aerobically and the other six lots were packaged using the MAP. A different combination of nisin (N) and/or lactic acid (LA) was added to each lot (300 ppm N, 500 ppm N; 2% LA; 300 ppm N and 2% LA; 500 ppm N and 2% LA). All samples were stored at 4 °C for 21 days (samples with MAP) or 7 days (samples stored aerobically). The inactivation of L. monocytogenes in samples stored aerobically was attained mainly with the combination of 500 ppm N + LA; however, in samples with MAP, the L. monocytogenes population decreased 3.45 log with the addition of LA, and the combination N + LA increased the inactivation other 0.5 log.

Restriction digestion analysis of the acyl transferase (AT) domain sequences of a polyketide synthase (PKS) gene was tested as a rapid method to identify isolates of Aspergillus tubingensis from grapes. Restriction endonuclease digestion of PKS products using the endonucleases BccI, HaeIII, HpaII, MboI and TaqI distinguished five types of restriction fragment length polymorphism (RFLP). Ochratoxigenic isolates were only identified within RFLP-types I and III. The RFLP assay is proposed as a rapid and easy method to identify A. tubingensis isolates from grapes. Amino acid sequences of AT domains from representative A. tubingensis isolates of the RFLP types obtained were aligned and analysed using phylogenetic methods. A comparison was also made with reference strains of Aspergillus section Nigri. Most of the A. tubingensis strains clustered into two distinct groups Gr1 and Gr2 with the exception of two isolates that remained unclustered. These results support the intraspeficific variability within A. tubingensis species reported using other techniques.

Samples from 240 carcasses were collected from four animal species (porcine, ovine, bovine and equine). Two samples were taken from each carcass, one using the excision method (EX) and the other the wet–dry swabbing method (SW). Eight areas from each carcass were sampled. Most of the samples obtained by SW revealed total aerobic viable counts (TVC) levels of between 3.1 and 4.0 log CFU cm−2, while most of the values corresponding to excision were located between 4.1 and 5.0 log CFU cm−2. Moreover, Enterobacteriaceae (EC) counts were only detected above 3.0 log CFU cm−2 in 0.85% of the carcasses when the samples were collected by swabbing, while the excision method revealed that 13.75% of the carcasses presented EC greater than 3.0 log CFU cm−2. TVC and EC by EX revealed statistically significant differences compared to SW, while no significant linear relationship was found between carcass surface bacterial counts obtained by SW and EX.

Fifty-five bovine, 50 equine, 60 ovine, and 50 porcine carcasses were sampled in a slaughterhouse in eastern Spain. Two samples were taken from each carcass, one using the excision method and the other using the swabbing method. Four different materials were used for swabbing: cellulose, polyurethane, or viscose sponges, and medical gauze. Samples were collected at the end of the process by four different people before the carcasses were taken to the cooler. The samples were examined for total viable bacteria counts (TVCs) and Enterobacteriaceae counts (ECs). The mean TVC for all species sampled by excision was 4.50 log CFU/cm(2), which was significantly higher than the 3.53 log CFU/cm(2) obtained by swabbing. The TVCs obtained using gauze and the cellulose and polyurethane sponges were significantly higher (P < 0.05) than the corresponding TVCs obtained using viscose sponges. Animal species, the person who collected the samples, and microbiological load also had a significant effect on TVC. ECs were obtained from 82.8% of excision samples, from larger percentages of samples obtained using cellulose or polyurethane sponges or gauze swabs, but from smaller percentages of samples obtained using viscose sponges. The Enterobacteriaceae load significantly influenced the EC. In contrast, animal species and the person who collected the samples had no significant effect. The cellulose sponge, polyurethane sponge, and gauze gave high mean log counts of aerobic bacteria and Enterobacteriaceae, which makes these swab types suitable for use in slaughterhouses for the purpose of assessing production process hygiene.

Objective: Lyophilization appears to be a viable method for storing human milk, assuring no microbiological contamination and preserving its health benefits and antibacterial properties. The aim of the study is to evaluate and compare the effects of different storage methods (lyophilization and freezing at −20°C and −80°C) and maternal factors (gestational length or time postpartum) upon the microbiological contents and bactericidal activity of human milk. The possible relation between bactericidal activity and the content of certain nutrients and functional components is also investigated. Methods: Microbiological content, bactericidal activity, sialic acid, and ganglioside contents, as well as protein, fat, and lactose concentrations were assessed in 125 human milk samples from 65 healthy donors in the Human Milk Bank of La Fe (Valencia, Spain). Results: Lyophilization and storage at −80°C significantly reduced the content of mesophilic aerobic microorganisms and Staphylococcus epidermidis when compared with storage at −20°C. Bactericidal activity was not significantly modified by lyophilization when compared with freezing at either −20°C or −80°C. Bactericidal activity was not correlated with fat, protein, or lactose content, but was significantly correlated to ganglioside content. The bactericidal activity was significantly greater (P < 0.05) in mature milk and in milk from women with term delivery than in milk from early lactation (days 1–7 postpartum) and milk from women with preterm delivery, respectively. Conclusions: Lyophilization and storage at −80°C of human milk yields similar results and are superior to storage at −20C with regard to microbial and bactericidal capacities, being a feasible alternative for human milk banks.

Fungi play a key role in dry-cured ham production because of their lipolytic and proteolytic activities. In the present study, 74 fungal strains from dry-cured Teruel hams and air chambers were tested for proteolytic and lipolytic activities, with a view to their possible use as starter cultures. Lipolytic activity of fungi was studied against lauric, palmitic, stearic and oleic acids, whereas proteolytic activity was studied against casein and myosin. Of the 74 fungal strains tested, most of them demonstrated lipolytic activity (94.59 %). Lipolytic activity against lauric and oleic acids was stronger than against palmitic and stearic acids. 39 strains (52.70 %) demonstrated proteolytic activity against casein and the 6 highest proteolytic strains were also tested for pork myosin proteolysis. Some strains belonging to Penicillium commune, Penicillium chrysogenum, Penicillium nalgiovense and Cladosporium cladosporioides were selected because of their significant proteolytic and lipolytic activities and could be suitable to use as starters in dry-cured ham.