AbstractWe evaluated the possibility of increasing the storage temperature of raw milk for Provolone Valpadana cheesemaking, to identify the most suitable conditions of time and temperature for a pre-maturation process. We used Principal Component Analysis (PCA) to analyze the overall effects of different storage conditions on chemical, nutritional and technological characteristics of the raw milk. Four different thermal storage cycles, two at fixed temperature/time (6 and 12°C for 60 h) and two with two-phase thermal cycle (10 and 12°C for 15 h, followed by refrigeration at 4°C for 45 h) were studied. Although a moderate heterogeneity among raw milks from the 11 producers of Provolone Valpadana cheese was observed, PCA revealed the critical aspects of the extreme storage conditions (60 h of refrigeration). Some samples resulted in anomalous behaviors, probably related to unexpected fermentation phenomena occurring with increasing storage temperature. The acidification and the increase in the contents of lactic acid, soluble calcium, and degree of retinol isomerization observed in the anomalous samples can compromise the technological functionality of milk. Conversely, the storage with a two-phase thermal cycle did not lead to variations in any measured characteristic, suggesting that mild refrigeration conditions (10 or 12°C for 15 h followed by 4°C for 45 h) could be a good compromise in favoring milk pre-maturation without altering its quality characteristics.

Our objective was to study the effect of increasing postruminal supply of linseed oil (L-oil), as a source of cis-9, cis-12, cis-15 18:3, on milk fatty acid profile and to assess the resulting impact on the development of volatile degradation products during the storage of homogenized milk. Five Holstein dairy cows fitted with a rumen cannula were randomly distributed in a 5 × 5 Latin square design. Abomasal infusion of L-oil was performed at the rate of 0, 75, 150, 300, and 600 ml/d during periods of 14 d. The concentration of cis-9, cis-12, cis-15 18:3 in milk fat increased linearly with L-oil dose. Concentrations of primary (conjugated diene and triene hydroperoxides) and secondary oxidation products (1-octen-3-one, propanal, hexanal, trans-2 + cis-3-hexenals, cis-4-heptenal, trans-2, cis-6-nonadienal trans-2, trans-4-nonadienal) increased during 11 d of storage at 4°C of homogenized milk under fluorescent light. The magnitude of the increase (difference between final and initial measurements) was linearly greater for all nine lipid oxidation products evaluated in response to increasing level of infusion. Results of the current experiment have shown that milk enriched in cis-9, cis-12, cis-15 18:3 via postruminal supply of L-oil is highly prone to oxidative degradation. This low oxidative stability, exposed under controlled experimental conditions, would represent a major obstacle to those who aim to market milk enriched in polyunsaturated fatty acids.

We evaluated the presence of bacterial pathogens in the milk of goats and their relationship with somatic cell count (SCC) and milk composition. The study was performed on a dairy farm in northern Slovakia. Half udder milk samples were collected from goats in June and July. The samples were divided on the basis of SCC into 4 bands (SCC1 lowest to SCC4 highest). Bacterial pathogens were only detected in 13% of samples. SCC3 and SCC4 had 15 and 25% positive samples respectively compared with SCC1 (2%) and SCC2 (14%). Coagulase-negative staphylococci (CNS) were the most common isolates (73%), of which Staphylococcus caprae was the most frequently isolated (65%). In samples with ≥ 1000 × 103 cells ml- 1 (SCC3, SCC4) there was higher somatic cell score (SCS) in the presence of a pathogen (7.48 ± 0.11) than without a pathogen (7.16 ± 0.05, P < 0.01). Statistically significant but weak negative correlations were observed between SCS and lactose, dry matter and non-fat dry matter. In conclusion, a higher percentage of bacteriologically positive milk samples was observed in both SCC3 and SCC4 groups but this does not explain the aetiology of high SCC in the milk of goats that are apparently free of bacteria. As a diagnostic tool, SCC is probably less useful in goats than in cows.

AbstractWe compared the virulence profile and REP-PCR genotypes of Escherichia coli strains isolated from subclinical and clinical mastitis cases and dairy farm environments in Minas Gerais State, Brazil, to determine virulence factors and genotypes potentially associated with subclinical persistence in the udder. The virulence profile was obtained by the search for three virulence genes: lpfA (long polar fimbriae), fliC (flagella), and escN (type III secretion system). Subclinical isolates exhibited mainly the fliC gene (33.33%) and fliC + escN genes (30.30%). Clinical isolates exhibited mainly fliC + escN genes (50%) and environmental isolates the lpfA + escN genes (58.04%). Strains isolated from subclinical mastitis showed 6.75 times more positivity to fliC than environmental isolates. Thirty-four genotypes were observed in the REP-PCR analysis, and clinical mastitis isolates indicated more genetic proximity to dairy farm environment isolates than subclinical mastitis isolates. In conclusion, the results suggested that flagella may be an important virulence factor for mammary persistent E. coli infection in cattle, however, none of the E. coli REP-PCR genotypes were associated with subclinical infection.

Eggnog, a dairy-based beverage, comprises both milk and egg proteins. We aimed at optimizing the eggnog formulation using Box-Behnken design of response surface methodology. The combined effects of milk (60-75), cream (25-35) and eggnog base (6-8, all three as g 100/ml) were investigated on heat coagulation time, viscosity and thermal gelation temperature. ANOVA indicated that experimental data were well explained by a quadratic model with high check values (R2 > 0.94) and non-significant lack of fit tests. Based on the responses, an optimized formulation of eggnog with 60.0 milk, 25.0 cream and 6.50 eggnog base (as g 100/ml), could be considered best for manufacturing eggnog with desired attributes. This optimized formulation was characterized for physico-chemical, microbial and sensory attributes and the results indicated significantly higher fat and protein content than control formulation, but lesser lactose and total sugar content. Significantly higher viscosity, heat stability and lower thermal gelation temperature were also observed for the optimized formulation. Coliform, yeast and mold, E. coli and Salmonella counts were not detected in any sample but a significantly lower total plate count was observed for the optimized formulation.

Exploration of novel strategies for early pregnancy diagnosis is pivotal in enhancing the reproductive potential and monetary gains from dairy herds. In buffalo, the trophectoderm cells of the elongating conceptus secrete interferon-tau that stimulates the transcription of various genes in peripheral blood mononuclear cells (PBMC) during the peri-implantation period. We explored the differential expression of classical (ISG15) and novel (LGALS3BP and CD9) early pregnancy markers in PBMC of buffaloes during various stages of pregnancy. Natural heat was detected in buffaloes by assessing the vaginal fluid, and artificial insemination (AI) was done. Whole blood was collected from the jugular vein in EDTA-containing vacutainers for PBMC isolation before AI (0-day) and 20, 25 and 40 d post-AI. On day 40, transrectal ultrasonography examination was performed to confirm pregnancy. The inseminated non-pregnant animals served as control. Total RNA was extracted using the TRIzol method. The temporal abundance of ISG15, LGALS3BP and CD9 genes in PBMC was compared between pregnant and non-pregnant groups (n = 9 per group) using real time-qPCR. Results showed transcripts of ISG15 and LGALS3BP were more abundant at 20 d in the pregnant group compared to the 0 d and 20 d values of the non-pregnant group. However, due to variability in expression, threshold (Ct) cycle of RT-qPCR alone could not distinguish pregnant and non-pregnant animals. In conclusion, ISG15 and LGALS3BP transcripts abundance in PBMCs are potential candidate biomarkers for early prediction of buffalo pregnancy 20-days post-AI, but further work is required to allow the development of a reliable new methodology.

We investigated four different production methods of Künefe cheese, emphasizing their industrial importance. The four methods used fresh Künefe cheese (FKC), salted Künefe cheese (SKC), Boru type Künefe cheese (BKC) and culture-added processed Künefe cheese (CPKC), all used in the production of Künefe, a syrupy dessert unique to the Middle East. FKC was produced as a result of curd formation from raw milk with rennet and then the fermentation of curd. SKC was manufactured using the salting method in addition to FKC production. BKC was obtained using the dry cooking process with emulsifying salts applied to cheese curd. CPKC was produced by applying heat treatment to raw milk and using starter culture before adding rennet that was different to Boru-type Künefe cheese. The composition, color, meltability, texture and sensory properties of the Künefe cheeses were examined. As a result of statistical analysis, it was determined that the effect of different production methods on the composition, meltability, texture (except springiness and cohesiveness) and sensory properties was significant in all cheeses (P < 0.05). CKPC was the most appropriate cheese in various properties.

AbstractThe aim in this research paper was to investigate the effect of using calcium monophosphate (MCP) and MCP mixed with commercial phosphates salts, in total or partial replacement of calcium chloride (CaCl2) in the manufacture of Minas Frescal cheese. Initially, model cheeses were made to perform the rheological analysis during the coagulation process. Of these, the five best treatments were chosen to carry out the production of Minas Frescal cheese, used only CaCl2 and MCP, and partial replacements of MCP + polyphosphate, MCP + potassium monophosphate (MKP) and MCP. The cheeses showed no significant difference in physicochemical composition, yield and syneresis, however, the cheese with partial replacement of CaCl2 by MCP + polyphosphate and MCP + MKP showed the highest hardness values, like the control. This demonstrates that it is possible to replace calcium chloride without significant changes in the physicochemical characteristics and yield of Minas Frescal cheese, and it is still possible to modulate the hardness of the cheese produced according to the type of calcium/phosphate source used. This allows the industry to replace the source of calcium in the manufacture of Minas Frescal cheese according to the desired hardness.

AbstractThe performance of the starter culture is a critical factor that decides the quality of fermented milk. Dahi is a fermented milk product popular in India made using a mixed starter culture of lactic acid bacteria comprising acid and flavour producers. The prevalence of bacteriophages in the dairy environment can critically affect the activity of these starter cultures resulting in starter failure. As there is little information available on the occurrence of bacteriophages in the dairy environment of Kerala, this research communication examines the presence of lytic bacteriophages acting against three potential flavour-producing strains of Lacticaseibacillus paracasei (Lc. paracasei). Dairy effluent samples were screened for the presence of phages against the strains of Lc. paracasei by the multiple host enrichment method. Plates showing clearance zone in spot assay were confirmed for the presence of phages by double-layer agar assay. The plaques obtained in the double-layer agar assay were purified for further identification by next-generation sequencing. A bacteriophage infecting one of the three strains of Lc. paracasei was detected by the plaque assay and the blast annotation of the bacteriophage sequence found 86.05% similarity of the phage to Siphoviridae family. The study endorses the need for monitoring phages in the dairy environment to control phage-related starter failure in the state of Kerala.

AbstractWe investigated sonication as a pre-processing step to reduce acid whey generation during Greek yoghurt manufacture. The generation of a large amount of acid whey during the production of Greek yoghurt is an ongoing problem in the dairy industry and many studies are currently focusing on reducing it. We focused on the use of ultrasonication as a novel approach to minimize the casein fraction in the acid whey stream and simultaneously improve the gel properties. Ultrasound applied before the fermentation modified the structural properties and bonding behaviours of milk proteins, and enhanced the retention of casein in the yoghurt gel after the fermentation and straining steps. Therefore, the use of low-frequency ultrasonication as a pre-processing step may have the potential to provide significant economic benefits to the Greek yoghurt manufacturing process. Moreover, it improved the nutritional and physicochemical properties compared to regular Greek yoghurts.