Enrichment of the conjugated linoleic acid content of bovine milk fat by dry fractionation

This study investigated the effect of fat fractionation on the conjugated linoleic acid (cis-9, trans-11-C_18 : 2) content of bovine milk fat. Anhydrous milk fat was fractionated into hard and soft fractions using controlled cooling and agitation. Fractionation of milk fat pre-melted at 60°C using a temperature programme of 33–10°C and a cooling rate of 0.58°C h⁻¹ yielded a soft fraction containing 63.2% more conjugated linoleic acid (2.22 g 100 g⁻¹ FAME), which was also enriched in polyunsaturated fatty acids and vaccenic acid (trans-11-C_18 : 1) compared with the parent fat. Agitation following fractionation was found to have a negative effect on the conjugated linoleic acid content of the soft fraction. Refractionation of the soft fraction did not increase the yield of conjugated linoleic acid. The conjugated linoleic acid and trans fatty acid content of 26 selected food products ranging in milk fat content from 0 to 100% is reported. Conjugated linoleic acid concentrations ranged from 0 to 16.2 mg g⁻¹ fat and were generally lower than the trans fatty acid content which ranged from 0 to 155.7 mg g⁻¹ fat. Spreads containing vegetable oils contained higher trans fatty acid and lower conjugated linoleic acid contents than milk fat-containing products. This study highlights that a milk fat fraction enriched in conjugated linoleic acid may be achieved by dry fractionation.     

Production of conjugated linoleic acid enriched milk and dairy products from cows receiving grass silage supplemented with a cereal-based concentrate containing rapeseed oil

Opportunities for the production of milk and dairy products enriched with cis-9, trans-11 conjugated linoleic acid (CLA) were investigated. Eighteen mid-lactation cows were used in a continuous-design for 7 weeks. During the first week, cows received grass silage ad libitum supplemented with 10 kg per day of a cereal-based concentrate (control) that was replaced with a concentrate containing 50 g kg⁻¹ of rapeseed oil (RO). Changes in milk fatty acid composition were monitored on a weekly basis and milk produced was used to manufacture Edam cheese and butter. Inclusion of RO in the concentrate supplement increased the mean levels of trans-octadecanoic, monounsaturated, CLA and polyunsaturated fatty acid in the milk fat from 1.6, 25.7, 0.46 and 2.8 to 4.3, 35.3, 1.02 and 3.9 g 100 g⁻¹ total fatty acids, respectively. In contrast, the mean level of saturated fatty acids decreased from 71.4 to 60.7 g  100 g⁻¹ total fatty acids. Changes in milk fatty acid composition due to RO occurred within 7 days, with responses reaching a plateau after 21 days. Furthermore, the CLA concentrations in the milk fat from individual cows ranged between 0.37 and 0.65 and 0.43 and 2.06 g 100 g⁻¹ total fatty acids for the control and RO diet, respectively. CLA enriched milk was used successfully to manufacture of Edam cheese and butter with softer textures but with acceptable organoleptic and storage properties. Processing milk into butter or cheese had no effect on the CLA concentrations indicating that enrichment of dairy products is dependent on the content in raw milk fat.     

Controlling moisture transport in a cereal porous product by modification of structural or formulation parameters

Equilibrium and dynamic water sorption properties of sponge cakes with varying porosity (86–52%) and fat content (0–0.30 g/g d.b.) were determined using a water vapour sorption microbalance. Contrary to porosity, addition of fat decreased equilibrium moisture contents. The effective moisture diffusivity (D_eff) was identified from a numerical solution of Fick’s second law, taking into account an external mass transfer coefficient and the swelling of the solid matrix. D_eff increased from 1.61 to 8.67 × 10⁻¹⁰ m²/s with moisture content, reached a threshold at moisture content 0.15 g/g d.b. and then decreased until water saturation. D_eff decreased from 8.67 to 2.97 × 10⁻¹⁰ m²/s with decreasing porosity. This effect was attributed to a change of water diffusion mechanism, from predominant vapour to liquid. D_eff decreased from 8.67 to 2.12 × 10⁻¹⁰ m²/s with increasing fat content. Addition of fat had an effect on the water diffusion in two ways, decreasing porosity (sagging of the foam) and increasing tortuosity.     

Effects of somatic cell counts in milk on physical and chemical characteristics of yoghurt

The quality of plain stirred yoghurt produced from whole milk with somatic cell counts (SCC) at low (147,000 cells mL⁻¹), intermediate (434,000 cells mL⁻¹) and high (1,943,000 cells mL⁻¹) levels was examined. Each milk treatment was obtained from selected cows, according to its SCC status and milk composition. Yoghurt samples were analysed on days 1, 10, 20 and 30 after production. Analyses included pH, acidity, fat, lipolysis (expressed as free fatty acids, FFA), proteolysis and apparent viscosity. Viscosity of high SCC yoghurt was higher (P<0.05) than the low SCC yoghurt on days 10, 20 and 30 of storage. High SCC yoghurt also had higher FFA content (P<0.05). SCC did not affect pH, acidity, fat content and proteolysis of the yoghurt (P>0.05). Results indicate that SCC in milk increases the lipolysis in the resulting yoghurt during storage for 30 d.     

Effect of commercial adjunct cultures on proteolysis in low-fat Kefalograviera-type cheese

The effect of two commercially available adjunct cultures, LBC 80 (Lactobacillus casei subsp. rhamnosus) and CR-213 (containing Lactococcus lactis subsp. cremoris and Lc. lactis subsp. lactis) on the proteolysis in low-fat hard ewes’ milk cheese of Kefalograviera-type was investigated. Two controls, a full-fat cheese (306 g kg⁻¹ fat, 378 g kg⁻¹ moisture) and a low-fat cheese (97 g kg⁻¹ fat, 486 g kg⁻¹ moisture, made using a modified procedure), were also prepared. The effect of adjunct culture on proteolysis, as examined by polyacrylamide gel electrophoresis of cheese and water soluble cheese extracts, was marginal. The reverse-phase HPLC peptide profiles of the water soluble extracts from low-fat cheeses were similar although some quantitative differences were observed between low-fat control cheese and experimental cheeses. The fat content as reflected by the differences in peptide profiles affected the pattern of proteolysis. Proteolysis, as measured by the percentage of total nitrogen soluble in water or in 120 g L⁻¹ trichloroacetic acid, was significantly (P<0.05) affected by the addition of adjunct cultures. Furthermore, the adjunct cultures enhanced the production of low molecular mass nitrogenous compounds; the levels of total nitrogen, soluble in 50 g L⁻¹ phosphotungstic acid, and of free amino acids were significantly (P<0.05) higher in the low-fat experimental cheeses than in the low-fat control cheese.     

HPLC of proteose peptones for evaluating ageing of packaged pasteurized milk

The proteolysis of casein (CN) occurring in packaged pasteurized milk (PM) during refrigerated storage was studied with relation to hygienic and microbiological characteristics of starting raw milk. Six batches of raw milk having standard plate count (SPC) from 1.5×10⁴ to 2.5×10⁵ cfu mL⁻¹ and somatic cell count (SCC) from 1.6×10⁵ to 4.4×10⁵ units mL⁻¹ were pasteurized (73 °C for 15 s), packaged and stored at 4 °C for 12 days. Capillary zone electrophoresis of CN showed breakdown of β-CN in all PM samples during storage. An HPLC method for monitoring proteose peptones (PP) formation was developed. Level of PP in PM samples increased, with keeping time from 667–789 to 947–1383 mg L⁻¹ and PP formation was significantly (P<0.05) related to SCC of starting raw milk. Electrospray ionization–mass spectrometry showed that PP were mainly represented by PP-5 from either A¹ or A² variants of β-CN. Five commercial samples of PM were analysed for PP formation during 14-day storage at 4 °C. Commercial samples prepared by microfiltration process or bactofugation combined with pasteurization showed the slowest formation of PP. The effect of storage temperature on PP formation was evaluated by keeping a conventional PM sample at either 8 or 12 °C for 12 days. Proteolysis of all major CNs upon action of plasmin and bacterial proteinases was observed under these conditions. PP level thus proves to be a reliable analytical index for evaluating the ageing of packaged PM during refrigerated storage.     

Time–temperature study of the kinetics of migration of DPBD from plastics into chocolate,chocolate spread and margarine

Migration of low molecular weight substances into foodstuffs is a subject of increasing interest and an important aspect of food packaging because of the possible hazardous effects on human health.The migration of a model substance (diphenylbutadiene) from low-density polyethylene (LDPE) was studied in foodstuffs with high fat contents: chocolate, chocolate spread and margarines (containing 61% and 80% fat).A simplifying mathematical model based on Fick’s diffusion equation for mass transport processes from plastics was used to derive effective diffusion coefficients which take also kinetic effects in the foods into account and to determine partition coefficients between plastic and food. With this model migration levels obtainable under other storage conditions can be predicted. The effective diffusion coefficients for both margarines stored at 5 °C (3.0–4.2 × 10⁻¹⁰ cm² s⁻¹) and at 25 °C (3.7–5.1 × 10⁻⁹ cm²  s⁻¹) were similar to each other, lower than for chocolate spread stored at 5 °C (9.1 × 10⁻¹⁰ cm² s⁻¹) and higher than the diffusion coefficient for chocolate stored at 25 °C (2.9 × 10⁻¹⁰ cm² s⁻¹). Good agreement was found between the experimental and the estimated data, allowing validation of this model for predicting diffusion processes in foodstuffs with high fat contents.     

Inhibition of Chymosin and the Coagulation of Para-Casein Micelles by Anions

The effect of monovalent anions on the coagulation of para-casein micelles was determined by monitoring light transmission after adding different Ca salts (40 mM) to partially hydrolyzed casein micelles. The release of macro-peptide by chymosin was quantified using fluorescamine. The average rate of the chymosin-initiated coagulation of casein micelles, approximated by the reciprocal of clotting time, was determined as a function of anion type and concentration to determine the simultaneous effects of anions on chymosin velocity and para-casein micelle aggregability.Chymosin velocity and the coagulation of para-casein micelles were progressively inhibited by anions; the larger the anion, the greater the inhibition (SCN⁻ > NO₃⁻ > Br⁻ > Cl⁻). This is attributed to the binding of anions to cationic binding sites on kappa-casein and para-kappa-casein. The relative effect of the larger anions compared with that of Cl⁻ on the average rate of the chymosin-initiated coagulation of casein micelles increased with anion concentration (6 to 120 mM) but became limited at 120 mM. In the presence of 120 mM SCN⁻, NO₃⁻ and Br⁻, the average rate of coagulation was 26, 59, and 78% of that obtained with 120 mM Cl⁻.The marked sensitivity of the interactions between chymosin and kappa-casein and between para-casein micelles to anion type support conclusions that cationic sites on kappa-casein are important in the mechanism of the chymosin-initiated coagulation of casein micelles. Thus, monovalent anions may be useful to elucidate the mechanism of protein-protein interactions in food systems.     

Biochemical changes throughout the ripening of a traditional Spanish goat cheese variety (Babia-Laciana)

The physico-chemical characteristics, proteolysis (classical nitrogen fractions, caseins and their degradation products and free amino acids), and lipolysis (fat acidity and free fatty acids) were studied throughout the ripening of three batches of Babia-Laciana cheese, a Spanish traditional variety made from raw goats’ milk. The main compositional characteristics of this cheese at the end of the ripening are its high content of total solids (TS) (78.0±2.4 g 100 g⁻¹ of cheese) and fat (61.1±1.2 g 100 g⁻¹ of TS), the presence of residual lactose (1.6±0.8 g 100 g⁻¹ of TS) and its low content of sodium chloride (1.1±0.7 g 100 g⁻¹ of TS) and ash (2.8±0.5 g 100 g⁻¹ of TS). Its pH values (4.44±0.72) are extraordinarily low. The evolution and final values of the different nitrogen fractions show that this cheese undergoes a very slight proteolysis, a fact which was corroborated when the caseins and their degradation products were quantified: β-casein did not undergo any modification throughout ripening, while only 21% of the α_s-caseins were degraded. Free amino acids content increased by a factor of about 7 throughout ripening, resulting in a high content of γ-amino butyric acid and a low content of glutamic acid at the end of the process. Fat acidity increased very slightly, approximately 4.5 times, during ripening, reaching final values of 3.5±2.2 mg KOH g⁻¹ of fat. The total free fatty acids content showed a similar evolution to fat acidity. At the end of the ripening process, the main free fatty acid was C_18:1, followed by C₁₆ and C₁₀.     

Milk enhances intestinal absorption of green tea catechins in in vitro digestion/Caco-2 cells model

The effect of milk on the absorption of polyphenols is still controversial so far. In order to determine the impact of milk addition on green tea catechins bioaccessibility and intestinal absorption an in vitro digestion/Caco-2 cell model was applied. Green tea extract (GTE) was solubilized in distilled water at 23 °C and 100 °C, combined with skimmed milk (GTE + 10% milk and GTE + 25% milk) and subjected to simulated gastric and intestinal digestion, followed by transepithelial absorption in Caco-2 cells monolayers. In the mixture with milk, gallated catechins: ECG and EGCG showed binding to milk proteins while EC and EGC seemed to have weaker affinity. Catechins were stable during gastric incubation and very sensitive to intestinal digestion. Bioaccessibility of green tea catechins brewed at 100 °C was higher than brewed at 23 °C. Catechins from digested GTE with 10% and 25% milk exhibited enhanced intestinal permeability in Caco-2 model in comparison to non-digested GTE and digested GTE without milk. Apparent permeability coefficients (P_app) of EGCG and ECG in digested GTE with 25% milk were significantly higher compared to those in GTE with 10% milk, and amounted to 2.41 × 10^− 6 cm/s and 1.39 × 10^− 6 cm/s. The recoveries of all catechins in GTE with milk in Caco-2 cells after 2 h incubation were significantly higher than that without milk. To summarize, these data suggest that milk addition may increase catechin bioavailability by enhancing their transepithelial absorption and uptake from green tea extract.     

Thin-layer drying characteristics and modelling of mint leaves undergoing microwave treatment

The effect of microwave drying technique on moisture content, moisture ratio, drying rate, drying time and effective moisture diffusivity of mint leaves (Mentha spicata L.) were investigated. By increasing the microwave output powers (180–900 W) and the sample amounts (25–100 g), the drying time decreased from 12.50 to 3.0 min and increased from 6.60 to 16 min, respectively. To determine the kinetic parameters, the drying data were fitted to various models based on the ratios of the differences between the initial and final moisture contents and equilibrium moisture content versus drying time. Among of the models proposed, the semi-empirical Midilli et al. model gave a better fit for all drying conditions applied. By increasing the microwave output powers and decreasing the sample amounts, the effective moisture diffusivity values ranged from 3.982 × 10⁻¹¹ to 2.073 × 10⁻¹⁰ m² s⁻¹ and from 9.253 × 10⁻¹¹ to 3.162 × 10⁻¹¹ m² s⁻¹, respectively. The activation energy was calculated using an exponential expression based on Arrhenius equation. The relationship between the drying rate constant and effective moisture diffusivity was also estimated; and gave a linear relationship.     

Analysis of cyclopiazonic acid in milk by capillary electrophoresis

A Micellar Electrokinetic Capillary Chromatography (MEKC) method to detect cyclopiazonic acid (CPA) in milk and compare its quantifying efficiency to the Reverse Phase Liquid Chromatography (RPLC) method was evaluated. Alkaline milk samples were defatted, then acidified before being twice liquid–liquid extracted with chloroform. Bare fused-silica capillary-extended light path with 50 μm i.d. and Nova-pak C18-column, were used for the CPA separation in MEKC and RPLC respectively. The analytical response was linear from 40 ppb to 100 ppm CPA in MEKC (correlation coefficient, r=0.99995). Recoveries of spiked CPA in milk were 78–81% over the range of 20 ppb to 500 ppb in MEKC and 71–80% in the range of 50 ppb to 500 ppb in RPLC. The detectable limit of CPA by MEKC was 0.27×10⁻⁰⁷ pg ml⁻¹. Capillary electrophoresis (MEKC) is a better and rapid method for CPA detection in milk.     

Fate of enterotoxigenic Staphylococcus aureus in the presence of nisin-producing Lactococcus lactis strain during manufacture of Jben,a Moroccan traditional fresh cheese

The inhibitory effect of nisin-producing Lactococcus lactis subsp. lactis UL730 on the growth of enterotoxigenic Staphylococcus aureus J10 during manufacture of Jben, a Moroccan traditional fresh cheese prepared from recombined milk, was investigated.With an inoculum level of 10³ cfu mL⁻¹, S. aureus was absent in Jben four days after inoculation when the nisin-producing lactococcus was used as lactic starter. In contrast, it survived after that period, when the starter was non-nisin-producing. No staphylococcal thermonuclease was detected in all Jben samples made from milk inoculated with S. aureus at the level of 10³ cfu mL⁻¹.With a higher inoculum of 10⁵ cfu mL⁻¹, S. aureus was still present in Jben after manufacture and persisted during the storage of the product for 3 days in the laboratory, even when the starter used was nisin-producing. Staphylococcal thermonuclease and type C enterotoxin were detected in all Jben samples made from milk inoculated with 10⁵ cfu mL⁻¹. Thermonuclease and enterotoxin were already produced in the coagulum, at 24 h after milk inoculation with S. aureus.     

Evaluation of pulsed electric field and minimal heat treatments for inactivation of pseudomonads and enhancement of milk shelf-life

Pulsed Electric Field (PEF) treatment of milk provides the opportunity to increase the shelf-life of fresh milk for distribution to distant markets. PEF treatments were evaluated in sterile (UHT) milk to determine the inactivation of added spoilage Pseudomonas isolates and the subsequent gains in microbial shelf-life (time taken to reach 10⁷ CFU mL^− 1). Little inactivation of Pseudomonas was achieved at 15 or 40 °C compared with 50 or 55 °C. The greatest inactivation (> 5 logs) was achieved by processing at 55 °C with 31 kV cm^− 1 (139.4 kJ L^− 1). Heat treatment at the application temperature without PEF treatment caused minimal inactivation of Pseudomonas (only 0.2 logs), demonstrating that the inactivation of the Pseudomonas was due to the PEF treatment rather than the heat applied to the milk. At added Pseudomonas levels of 10³ and 10⁵ CFU mL^− 1, the microbial shelf-life of PEF-treated milk was extended by at least 8 days at 4 °C compared with untreated milk. The total microbial shelf-life of the PEF-treated milk was 13 and 11 days for inoculation levels of 10³ and 10⁵ CFU mL^− 1 respectively. The results indicate that PEF treatment is useful for the reduction of pseudomonads, the major spoilage bacteria of milk.Industrial relevancePseudomonads are the major psychrotrophic spoilage microflora of refrigerated, stored HTST pasteurised milk. Long-life (UHT) products are an important component of milk sales in South-East Asia, but in recent years there has been an increasing demand for less processed milk products with extended shelf-life. The recent practice of shipping fresh bulk milk from Australia to South-East Asian countries has necessitated additional heat treatment prior to export and on arrival, to achieve the required shelf-life. Pulsed electric field treatment of HTST milk, applied alone or in combination with mild heat under optimised conditions, offers the opportunity of shelf-life extension, while limiting the reduction in quality attributes of milk associated with more severe additional heat treatments.     

Polar lipids,sphingomyelin and long-chain unsaturated fatty acids from the milk fat globule membrane are increased in milks produced by cows fed fresh pasture based diet during spring

Milk lipids are an interesting source of bioactive molecules with functional and nutritional properties. Although the composition of milk lipids is of utmost importance for food processing and human consumption, it is far from being fully known. The objective of this study was to perform a comparative analysis of the chemical composition of lipids from bovine milks produced in French Brittany during spring (fresh pasture based diet) and winter (corn silage based diet). The polar lipid content and relative proportions of the glycerophospholipids and sphingomyelin were determined using HPLC/ELSD. The fatty acid composition of total lipids and polar lipids was determined using GC. The milks collected in spring contained i) a lower amount of total lipids: 39.7 ± 0.8 g/kg vs 41.7 ± 0.5 g/kg in winter, ii) a higher amount of polar lipids: 138 ± 11 vs 112 ± 8 mg/kg milk; 3.5 ± 0.3 vs 2.7 ± 0.4 mg/g fat, which was related to a smaller size of fat globules, and iii) a higher amount of sphingomyelin, 32 mg/kg milk vs 25 mg/kg milk in winter. Interestingly, the polar lipids from the milk fat globule membrane contained a higher concentration of unsaturated fatty acids in spring (C18:1 n − 9, C18:2 n − 6, C18:3 n − 3 and long-chain n − 3 fatty acids). Milk from cows fed a fresh pasture-based diet during spring is an interesting source of dietary long chain polyunsaturated fatty acids for human consumption.     

High-pressure and temperature effects on the inactivation of Bacillus amyloliquefaciens,alkaline phosphatase and storage stability of conjugated linoleic acid in milk

Milk rich in conjugated linoleic acid (CLA, 42 ± 3 mg g^− 1 fat) was used to evaluate the impact of high-pressure sterilization (HPS). The pressure, temperature and time needed to reduce 7-log of Bacillus amyloliquefaciens endospores were determined in the presence of nisin (4–64 mg L^− 1). In addition, the inactivation of alkaline phosphatase was evaluated. After HPS treatment, the remaining CLA and formation of hydroperoxides were monitored during storage up to 60 d at 25 °C. The addition of nisin (≥ 16 mg L^− 1) to milk significantly enhanced the inactivation of B. amyloliquefaciens (7-log reduction) after treatment at 600 MPa, 120 °C and 5 min of holding time. These conditions were selected to evaluate the impact of HPS on the CLA retention and hydroperoxides formation. Milk with the addition of nisin and treated with HPS delivered higher retention of CLA and a lower concentration of hydroperoxides compared with the UHT equivalent process (125 °C/15 s and 135 °C/10 s).Industrial relevanceHigh-pressure sterilization is a valuable alternative to produce superior quality milk products in cases where traditional thermal treatments have failed. This study evaluated the impact of processing conditions on the conjugated linoleic acid content at conditions where commercial sterilization has been achieved (7-log reduction of B. amyloliquefaciens). The outcomes of this study are considered as a step further for the development of high-pressure sterilized milk.     

Effect of tomato by-products in the diet of Comisana sheep on composition and conjugated linoleic acid content of milk fat

To evaluate the effect of supplementing the diet of Comisana sheep with by-products from industrial tomato manufacture on the fat composition and conjugated linoleic acid (CLA) content of milk fat, two groups of 50 ewes each were fed either total mixed ration standard (TMRS) or total mixed ration with added tomato by-products (TMRA). Milk fat composition was determined by high-resolution gas chromatography (HRGC). The milk fat content for the animals fed the TMRA diet increased by 6.41% (P < 0.01) after six weeks, compared with the animals fed the TMRS diet. The CLA content in the milk fat for the group of animals fed the TMRA diet was 19.8% (P < 0.05) higher than for those fed the TMRS diet, and reached 1.33 g 100 g^?1 fat, while the polyunsaturated fatty acid (PUFA) content increased by a 6.43% (P < 0.05) and reached 7.12 g 100 g^?1 fat. The fatty acid composition showed an increase in the amount of polyunsaturated fatty acids. The n ? 3:n ? 6 ratio increased by 13% in the milk from sheep fed with the TMRA diet. These observations were confirmed by triglyceride analysis, which showed a decrease in the amount of short-chain (C₂₈–C₃₂) and medium-chain (C₃₄–C₄₂) triglycerides after six weeks, while the opposite was observed for the long-chain triglycerides (C₄₄–C₅₄).     

The effect of sonication and high pressure homogenisation on the properties of pure cream

The homogenisation of milk and cream has been widely studied but the effect of sonication on the structural and functional properties of cream is not well known. In this study, raw milk, ultrafiltration retentate and cream samples were sonicated at 20 kHz and the rennet and acid gelation properties of these sonicated samples investigated. High pressure homogenisation at 80 bar was also performed for comparison. Sonication of raw milk and retentate samples led to a decrease in the fat globule size. Conversely, the fat globules in cream samples sonicated at < 10 °C flocculated to form grapelike structures whereas the cream samples sonicated at 50 °C did not form such aggregates. High pressure homogenisation at 50 °C led to similar flocculated structures, but these were not observed at low temperatures. This suggests a potential benefit of sonication technology in allowing low temperatures to be utilised for cream homogenisation, reducing energy demand. However, a gel made using cheese-milk with sonicated cream resulted in separation of a fat layer rather than the incorporation of the fat globules into the gel matrix. Rennet gelation properties of both the sonicated or homogenised samples were significantly superior to a native control sample where the resultant gels had shorter coagulation times and decreased syneresis.Industrial RelevanceHomogenisation of dairy cream is normally carried out at temperatures of around 50 °C, to ensure that the fat is in the liquid state. In this work, we show that we can achieve comparable changes to the fat globules within the cream using ultrasound at much lower temperatures (< 10 °C). The ability to form flocculated fat particles at lower temperatures could lead to reduced costs through reduced energy demand.     

Persistence and Biofilm Assessment of Campylobacter Jujeni in Poultry Abattoir

Persistence of Campylobacter sp and its biofilm forming ability was assessed in two poultry abattoirs at two weeks intervals. Average prevalence (63.75%) of Campylobacter spp. was observed on assessing a total of 160 samples collected from the surfaces of packaging table (80%), dressing table (75%), floor source (70%) and washing table (30%). Biofilm assessment formed by Campylobacter jejuni within 5-days at 37°C were in decreasing order of washing table > packaging table > dressing table > floor. An average rate (19.6%) of isolates to develop biofilm observed in both sites was considered relatively low. Absorbance value (Optical Density-OD_590nm) of formed biofilms ranged from 0.483 – 0.952. Wastewater from the facilities showed higher TDS (643 – 820 mgl⁻¹), TSS (1200 – 1775 mgl⁻¹), COD (152 – 141 mgl⁻¹) and BOD (30.3 – 32.5mgl⁻¹) than the WHO standards of 500 mgl⁻¹, 100 mgl⁻¹, 10 mgl⁻¹ and 6 mgl⁻¹ respectively. This is a clear indication of heavy microbial presence in the wastewater. Total bacterial count (TBC) was slightly higher in site A (4.4 × 10⁵ CFU/ml) than site B (3.5 × 10⁵ CFU/ml). Efficiency index ratio (≈/> 1) observed in all tested drugs suggests their effectiveness in campylobacteriosis management. Decreasing drug sensitivity pedigree was observed with streptomycin > erythromycin & gentamincin > tetracycline & neomycin > penicillin > riphapicin & ampicillin > norflaxicin & cephalexin. These results of frequency and biofilm forming tendencies of Campylobacter spp. observed in this study can be of value in checkmating campybacteriosis outbreak from poultry abattoir facility.     

A comparison of the chemical,microbiological and sensory characteristics of bovine and ovine Halloumi cheese

Commercial samples of fresh and mature Halloumi cheeses made from ovine or bovine milk were studied in order to establish their chemical, microbiological and sensory characteristics. Significant differences were observed between the two types of Halloumi cheese both when fresh and mature. The free volatile fatty acid (FVFA) content of the cheeses increased with maturation from 483 to 1356 mg kg⁻¹ for the ovine product, but lower values (380–1248 mg kg⁻¹) were found in the bovine cheese. During maturation for 40 days, Enterococcus faecium, which dominated the microflora of fresh ovine cheese, was replaced by lactobacilli, including a new species, Lactobacillus cypricasei, which was not found in the bovine samples. Fewer than 100 cfu g⁻¹ lactic acid bacteria (LAB) were present in the fresh bovine cheeses, but a microflora dominated by lactobacilli developed with time. Yeast counts in the mature ovine and bovine cheeses reached 2.3–2.8×10⁵ cfu g⁻¹ and, as some of the yeasts were proteolytic and/or lipolytic, it was assumed that they were having a positive impact of the flavour of the cheeses. The sensory panel distinguished significant differences in texture and flavour between the fresh and mature samples of both ovine and bovine cheeses and, overall, there was a significant preference for the ovine brand.