Survey on the fatty acids profile of fluid goat milk

Fluid goat milk submitted to thermal treatment has interesting nutritional properties and a potential expanding market. The present study was aimed to conduct fatty acids profile characterisation of goat milk placed on market. Forty-nine fluid milk samples were collected: 12 pasteurised, 12 pasteurised at high temperature, 11 ultrahigh temperature (UHT) whole milk and 14 UHT semi-skimmed milk. Milk samples were collected at retail level from 7 different companies and from different production batches. After extraction and methilation, fatty acids (FAs) profile was determined on each sample using a gas chromatograph with flame ionisation detector (GC-FID) with high-polarity capillary column. The concentration (g/100mL) of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), trans fatty acids (t-FAs), and isomers of conjugated linoleic acid (CLA) was determined. N-6/n-3 ratio, atherogenic index (AI) and thrombogenic index (TI) were also assessed. Fluid goat milk lipid profile was characterised by SFAs (68.4% of total FAs), PUFAs (5.3%), MUFAs (21.3%), t-FAs (3.6%) and CLA (0.8%). The most represented fatty acids were: 16:0 (24.5%), 9cis-18:1 (18.2%), 18:0 (9.6%), 14:0 (9.5%), 10:0 (9.3%) and 12:0 (4.5%). Nutritional indices were 2.8-6.8 for n-6/n-3 ratio; 2.3-2.9 for AI; and 2.7-3.2 for TI. Milk produced by small scale plants, with no milk fat standardisation, showed greater differences in fatty acid profile as compared to industrial plants milk. Large scale production is characterised by commingled bulk tank milk of different origins and then is more homogeneous. The whole goat milk supply chain should be controlled to obtain milk with fatty acids of high nutritional value

Hygienic and sensory quality factors affecting the shelf-life of Fruhe (Casu axedu) traditional Sardinian fresh cheese

A study was conducted to evaluate the dura- bility of the traditional fresh soft cheese Fruhe manufactured in Sardinia either from goats’ or sheep’s milk. Four farmstead cheese-making plants were visited three times during the Fruhe cheese-making season. During each visit environmental samples were collected from food contact and non-food contact sur- faces in order to evaluate the presence of Enterobacteriaceae, Escherichia coli, Pseudomonas spp. and Listeria spp. In a total of 60 environmental samples, Escherichia coli and Listeria spp. were never detected, while contamination with Enterobacteriaceae and Pseudomonas spp. was observed respectively in 48% and 43% of samples. The microbiological profile of 48 Fruhe cheese samples was assessed at different time points during the product shelf-life. Aerobic mesophilic bacteria, Enterobacteriaceae, E. coli, Pseudomonas spp., Bacillus cereus and Listeria monocytogenes were investigated at 0, 7, 14 and 21 days after production. E. coli, L. monocytogenes and B. cereus were never detected in the product. Enterobacteriaceae contamination was observed, showing decreasing levels over time. Pseudomonas spp. was recovered in only two Fruhe samples (3.3%) at day 0. Sensory analysis was also conducted using a triangle test to determine whether a difference between Fruhe samples at 14 and 21 days of shelf-life exists. Based on the evolution of the microbiological profile and the sensory attributes observed in the present study, it is reasonable to assume that the product shelf-life can be feasibly extended up to 21 days

Comparison of γ-aminobutyric acid and biogenic amine content of different types of ewe’s milk cheese produced in Sardinia, Italy

The bioactive compounds γ-aminobutyric acid (GABA) and biogenic amines (BA), together with protein-free amino acids, were measured by high-performance liquid chromatography in ewe’s milk cheeses produced in Sardinia with different technological traits. The study included three types of cheese: Pecorino Sardo PDO, Pecorino and Casu Marzu. Farmhouse Casu Marzu and Pecorino showed GABA content (maximum levels: 1001.3 and 378.1 mg 100 g^–1 respectively) that had never been found so high in cheese before, suggesting that these types of cheese present ideal conditions to produce GABA. These two types of cheese also showed high levels of BA (their total maximum levels were 1035.7 and 288.0 mg 100 g^–1 respectively). Pearson correlation analysis detected significant correlation between GABA and the main BA present in the cheeses (tyramine, cadaverine and putrescine), suggesting that the factors affecting the production of GABA are the same as those influencing BA formation

Listeria monocytogenes contamination in dairy plants: evaluation of Listeria monocytogenes environmental contamination in two cheese-making plants using sheeps milk

Listeria monocytogenes harbouring niches established in the processing plant support post-process contamination of dairy products made from pasteurised or thermised milk. The present study investigated L. monocytogenes environmental contamination in two sheep’s milk cheese-making plants. Persistence of contamination in the area at higher risk was also investigated. During a one-year survey 7 samplings were carried out in each dairy plant, along the production lines of Pecorino Romano and ricotta salata cheese. A total of 613 environmental samples collected from food contact and non-food contact surfaces were analysed according to ISO 11290-1:2005 standard method. Identification of the isolated strains was carried out by polymerase chain reaction. L. monocytogenes prevalence was 23.2% in dairy A and 13.1% in dairy B, respectively. The higher prevalence rate was found in the following areas: salting, products washing, packaging, ricotta salata storage and Pecorino Romano ripening rooms. L. monocytogenes was never found in the cheese-making area. The probability of observing samples positive for the presence of L. monocytogenes was asso- ciated with dairy plant, sampling area and the period of cheese-making (P<0.001). The greater persistence of contamination over time was observed in the washing, salting, and Pecorino Romano ripening areas. The control of persistent environmental contamination relies on the identification of L. monocytogenes niches within the processing environment and the prevention of harborage sites formation. The importance of strict cleaning and sanitising procedure in controlling L. monocytogenes environmental contamination is confirmed by the lower level of contamination observed after these procedures were correctly implemented

Listeria monocytogenes contamination in dairy plants: evaluation of Listeria monocytogenes environmental contamination in two cheese-making plants using sheeps milk

Listeria monocytogenes harbouring niches established in the processing plant support post-process contamination of dairy products made from pasteurised or thermised milk. The present study investigated L. monocytogenes environmental contamination in two sheep’s milk cheese-making plants. Persistence of contamination in the area at higher risk was also investigated. During a one-year survey 7 samplings were carried out in each dairy plant, along the production lines of Pecorino Romano and ricotta salata cheese. A total of 613 environmental samples collected from food contact and non-food contact surfaces were analysed according to ISO 11290-1:2005 standard method. Identification of the isolated strains was carried out by polymerase chain reaction. L. monocytogenes prevalence was 23.2% in dairy A and 13.1% in dairy B, respectively. The higher prevalence rate was found in the following areas: salting, products washing, packaging, ricotta salata storage and Pecorino Romano ripening rooms. L. monocytogenes was never found in the cheese-making area. The probability of observing samples positive for the presence of L. monocytogenes was asso- ciated with dairy plant, sampling area and the period of cheese-making (P<0.001). The greater persistence of contamination over time was observed in the washing, salting, and Pecorino Romano ripening areas. The control of persistent environmental contamination relies on the identification of L. monocytogenes niches within the processing environment and the prevention of harborage sites formation. The importance of strict cleaning and sanitising procedure in controlling L. monocytogenes environmental contamination is confirmed by the lower level of contamination observed after these procedures were correctly implemented

Hygienic and sensory quality factors affecting the shelf-life of Fruhe (Casu axedu) traditional Sardinian fresh cheese

A study was conducted to evaluate the dura- bility of the traditional fresh soft cheese Fruhe manufactured in Sardinia either from goats’ or sheep’s milk. Four farmstead cheese-making plants were visited three times during the Fruhe cheese-making season. During each visit environmental samples were collected from food contact and non-food contact sur- faces in order to evaluate the presence of Enterobacteriaceae, Escherichia coli, Pseudomonas spp. and Listeria spp. In a total of 60 environmental samples, Escherichia coli and Listeria spp. were never detected, while contamination with Enterobacteriaceae and Pseudomonas spp. was observed respectively in 48% and 43% of samples. The microbiological profile of 48 Fruhe cheese samples was assessed at different time points during the product shelf-life. Aerobic mesophilic bacteria, Enterobacteriaceae, E. coli, Pseudomonas spp., Bacillus cereus and Listeria monocytogenes were investigated at 0, 7, 14 and 21 days after production. E. coli, L. monocytogenes and B. cereus were never detected in the product. Enterobacteriaceae contamination was observed, showing decreasing levels over time. Pseudomonas spp. was recovered in only two Fruhe samples (3.3%) at day 0. Sensory analysis was also conducted using a triangle test to determine whether a difference between Fruhe samples at 14 and 21 days of shelf-life exists. Based on the evolution of the microbiological profile and the sensory attributes observed in the present study, it is reasonable to assume that the product shelf-life can be feasibly extended up to 21 days