Contaminazioni da aflatossina M₁ nella filiera del latte ovino in Sardegna

The main objective of the thesis was to investigate the level of aflatoxin M1 contamination in the dairy sheep sector in Sardinia (Italy). The first contribution was a survey on the level of aflatoxin M1 contamination of small ruminant raw milk collected in Sardinia. Raw milk samples were collected at farm level from bulk tanks, from tank trucks and also at plant level from silo tanks. Overall were collected 517 sheep and 88 goat milk samples. Analysis for the detection of aflatoxins M1 were performed using high-performance liquid chromatography. Only one sheep bulk tank milk sample exceeded the EU limit (50 ng/kg). The second contribution of the thesis was aimed to investigate the presence of aflatoxin M1 of Pecorino Romano cheese and to compare the level of contamination with other long ripened cheeses produced using cow’s milk. A total of 108 Pecorino Romano, 40 Grana Padano and 32 Parmigiano Reggiano cheese samples were analyzed by high performance liquid chromatography-mass spectrometry. Only 5.6% of Pecorino Romano samples were above the detection limit of the method (30 ng/kg) but always within the maximum residues levels for long ripened cheeses (275 ng/Kg). The lower risk of aflatoxins M1 contamination in dairy sheep milk sector as compared to dairy cow’s sector is due to differences in the farming systems, in the lower carry-over of small ruminants and in the greater impact of dilution effect in the milk picking system adopted by sheep milk plants

Texture and sensory changes of a fresh ewe's cheese packed under different modified atmospheres

Shelf-life extension of fresh ewe's milk cheese packaged with three different MAP conditions was studied. Fresh cheeses were stored in barrier trays, hermetically sealed with a barrier to gas and water film. The gas mixtures used were: 20%CO2/80%N2, 30%CO2/70%N2 and 50%CO2/50%N2. Trays were stored at 4°C and inspected at 0,7, 14 and 21 days. Physical-chernical and rnicrobiological analyses (pH, colour, dry matter, aw, mesophilic micro-organisms, psychrotrops, total coliforrns, Escherichia coli, Salmonella, Staphilococcus aureus and Listeria monocytogenes), gas composition inside the packaging (CO2, O2 and N2), texture analysis (puncture test and Texture Pro file Analysis-TPA) and sensory evaluation (acceptability test by scoring for colour, flavour, taste and texture) were carried out. Samples packaged with 30%CO2/70% N2 and 50%CO2/50% N2 had a shelf life of 21 days. Pathogens were not found during all the storage. Cheese stored with 30%CO2/70%N2 reached the best acceptability score to the sensory evaluation

Evoluzione chimico-fisica, sensoriale e della texture di un formaggio fresco pecorino confezionato in atmosfera modificata durante la shelf-life

This paper reports the results obtained from the analysis of a fresh ewe’s cheese packed under different modified atmospheres during the shelf- life. Cheese stored in 80% N2/20% CO2, at the end of the shelf-life was better than cheese packed with a 10% CO2, both for sensory characteristics and for rheological parameters, specially for the puncture force and hardness and chewiness obtained from the TPA assay. The colour was slightly more yellow than the cheese stored with 10% CO2. Il presente lavoro riporta i risultati ottenuti dall’analisi di un formaggio pecorino fresco conservato in atmosfera modificata mediante due differenti condizioni e prodotto ad una settimana di distanza uno dall’altro. L’analisi dei cambiamenti fisico-chimici, di texture e sensoriali durante la shelf-life, ha evidenziato che il campione conservato in atmosfera modificata con una percentuale di N2/CO2 pari a 80/20 si è rivelato qualitativamente superiore rispetto a quello conservato con una percentuale di N2/CO2pari a 90/10, sia per quanto concerne le caratteristiche sensoriali sia per i parametri di texture, in particolar modo per la forza alla rottura in compressione e per la durezza e masticabilità all’analisi TPA, anche se ha mostrato un ingiallimento del colore leggermente superiore rispetto alla prova conservata in miscela di gas 90/10

A Survey on aflatoxin M₁ content in sheep and goat milk produced in Sardinia region, Italy (2005-2013)

In the present work the results of a survey conducted in Sardinia Region on Aflatoxin M1 (AFM1) contamination in milk of small ruminants from 2005 to 2013 are reported. A total of 517 sheep and 88 goat milk samples from bulk tank, tank trucks and silo tank milk were collected. Analyses were performed by the Regional Farmers Association laboratory using high-performance liquid chromatography following the ISO 14501:1998 standard. None of the sheep milk samples analysed during 2005- 2012 showed AFM1 contamination. In sheep milk samples collected in 2013, 8 out of 172 (4.6%) were contaminated by AFM1 with a concentration (mean±SD) of 12.59±14.05 ng/L. In one bulk tank milk sample 58.82 ng/L AFM1 was detected, exceeding the EU limit. In none of goat milk samples analysed from 2010 to 2012 AFM1 was detected. In 2013, 9 out of 66 goat milk samples (13.6%) showed an AFM1 concentration of 47.21±19.58 ng/L. Two of these samples exceeded the EU limit, with concentrations of 62.09 and 138.6 ng/L. Higher contamination frequency and concentration rates were detected in bulk tank milk samples collected at farm than in bulk milk truck or silo samples, showing a dilution effect on AFM1 milk content along small ruminants supply chain. The rate and levels of AFM1 contamination in sheep and goat milk samples were lower than other countries. However, the small number of milk samples analysed for AFM1 in Sardinia Region in 2005-2013 give evidence that food business operators check programmes should be improved to ensure an adequate monitoring of AFM1 contamination in small ruminant dairy chain

Assessment of membrane processing plant for whey concentration in ovine dairy industry

Decrease of pollution potential, volume reduction and recovery of valuable components are the key aspects that are concerned with the economical convenience of whey processing technologies. Among membrane applications, reverse osmosis (RO) can be effectively used for achieving the separation of salt, protein and and lactose from whey and deproteinized whey (scotta). This study reports the operational results of a polymeric membrane continuous system, based on RO technology, recently installed in a sheep cheese factory which produces a total volume of 22 millions liters of scotta per year. Energy requirements and economical performances have been also evaluated in comparison to the previous management practices. Plant processing capacity, with a pressure level set at 35 bars, was about 10,000 L h-1, while the volume concentration ratio (VCR) was on average 2.8. In comparison to raw scotta, the concentration process decreased the costs associated to transport and refrigeration, while the selling price of retentate was higher. While the RO treatment of scotta required an average cost of 0.008 € L-1, the use of this technology generated a positive income of about 70,000 € per year. Permeate resulting from membrane processing (roughly 63% of the initial whey volume) which COD=700-800 mg L-1 was much lower than dairy wastewaters, could be further processed by RO to produce and recycle purified water

Extending the shelf life of fresh ewe’s cheese by modified atmosphere packaging

This study evaluated the effect of modified atmosphere packaging (MAP) in extending the shelf life of a fresh ewe’s cheese stored at 4 °C for 21 days. Three batches were prepared with 20, 30 or 50% CO2 with N2 as filler gas. MAP controlled well the microbial growth, and the best result was obtained with 50% CO2. Pathogens were not detected in any sample. Softening of cheese was best reduced by 30% or 50% CO2. The sensory characteristics of the cheeses markedly decreased during storage. Only the sample stored with 50% CO2 obtained an overall score above the acceptability at 14 days

A survey on Aflatoxin M1 content in sheep and goat milk produced in Sardinia Region, Italy (2005-2013)

In the present work the results of a survey conducted in Sardinia Region on Aflatoxin M₁ (AFM₁) contamination in milk of small ruminants from 2005 to 2013 are reported. A total of 517 sheep and 88 goat milk samples from bulk tank, tank trucks and silo tank milk were collected. Analyses were performed by the Regional Farmers Association laboratory using high-performance liquid chromatography following the ISO 14501:1998 standard. None of the sheep milk samples analysed during 2005- 2012 showed AFM₁ contamination. In sheep milk samples collected in 2013, 8 out of 172 (4.6%) were contaminated by AFM₁ with a concentration (mean±SD) of 12.59±14.05 ng/L. In one bulk tank milk sample 58.82 ng/L AFM₁ was detected, exceeding the EU limit. In none of goat milk samples analysed from 2010 to 2012 AFM₁ was detected. In 2013, 9 out of 66 goat milk samples (13.6%) showed an AFM₁ concentration of 47.21±19.58 ng/L. Two of these samples exceeded the EU limit, with concentrations of 62.09 and 138.6 ng/L. Higher contamination frequency and concentration rates were detected in bulk tank milk samples collected at farm than in bulk milk truck or silo samples, showing a dilution effect on AFM₁ milk content along small ruminants supply chain. The rate and levels of AFM₁ contamination in sheep and goat milk samples were lower than other countries. However, the small number of milk samples analysed for AFM₁ in Sardinia Region in 2005-2013 give evidence that food business operators check programmes should be improved to ensure an adequate monitoring of AFM₁ contamination in small ruminant dairy chain