The experiments reported in this Research Communication aimed to determine if a domestic strip test to detect ethanol residues in breast milk (Milkscreen®) is comparable to a previously established official method for detecting ethanol residues in milk. The two methods are examined in terms of overall sensitivity, robustness against storage and acidity and selectivity against formaldehyde residues. Here, Milkscreen® provided advantages, with faster results (2 min), good sensitivity (≥0.017%), no false results due formaldehyde residues and equal robustness against storage, but with lower sensitivity in acid milk samples. In summary, strip tests for the rapid detection of ethanol residues in breast milk can be used for screening purposes by dairy manufacturers, combining it with the official method to make a final diagnosis.

The bovine whey consists of more than 200 different types of proteins, of which β-lactoglobulin, α-lactalbumin, serum albumin, immunoglobulins and lactoferrin predominate. However, their concentrations are not stable due to the existence of protein dynamics during a transition from colostrum secretion to mature milk. To evaluate the dynamics of whey proteins of Jersey cows during a colostral phase and first month of lactation and an influence of the number of lactations, 268 milk samples from 135 Jersey cows were selected through a clinical evaluation. Whey was obtained by rennet coagulation of the mammary secretion. The concentration of total proteins was determined by the biuret method and their fractions were identified by 12% dodecyl sulfate-polyacrylamide gel electrophoresis (12% SDS-PAGE). Maximum concentrations of all protein fractions were observed in the first 12 h of lactation, reducing over the course of the study. Modification of the protein predominance was also observed. The transition from colostrum secretion to milk occurred between 24 and 72 h postpartum. There was an influence of the number of lactations on the dynamics of whey proteins, indicating that multiparous cows had better immunological and nutritional quality when compared to primiparous cows.

The experiments reported in this research paper aimed to investigate differences in the levels of chlorate (CHLO), perchlorate (PCHLO), trichloromethane (TCM) and iodine residues in bulk tank (BT) milk produced at different milk production periods, and to monitor those levels throughout a skim milk powder (SMP) production chain (BTs, collection tankers [CTs], whole milk silo [WMS] and skim milk silo [SMS]). Chlorate, PCHLO and iodine were measured in SMP, while TCM was measured in the milk cream. The CHLO, TCM and iodine levels in the mid-lactation milk stored in the WMS were lower than legislative and industrial specifications (0.0100 mg/kg, 0.0015 mg/kg and 150 µg/l, respectively). However, in late-lactation, these levels were numerically higher than the mid-lactation levels and specifications. Trichloromethane accumulated in the cream portion after separation. Perchlorate was not detected in any of the samples. Regarding iodine, the levels in mid-lactation reconstituted SMP were higher than that required by manufacturers (100 µg/l), indicating that the levels in milk should be lower than 142 µg/l. The higher residue levels observed in late-lactation could be related to the low milk volume produced during that period and changes in sanitation practices, while changes in feed management could have affected iodine levels. This study could assist in controlling and setting limits for CHLO, TCM and iodine levels in milk, ensuring premium quality dairy products.

This research communication reports the evaluation of cathelicidin in dairy goat milk for its relationship with the somatic cell count (SCC) and microbial culture results. Considering the limited performances of SCC for mastitis monitoring in goats, there is interest in evaluating alternative diagnostic tools. Cathelicidin is an antimicrobial protein involved in innate immunity of the mammary gland. In this work, half-udder milk was sampled bimonthly from a herd of 37 Alpine goats along an entire lactation and tested with the cathelicidin ELISA together with SCC and bacterial culture. Cathelicidin and SCC showed a strong correlation (r = 0.72; n = 360 milk samples). This was highest in mid-lactation (r = 0.83) and lowest in late lactation (r = 0.61), and was higher in primiparous (0.80, n = 130) than in multiparous goats (0.71, n = 230). Both markers increased with stage of lactation, but cathelicidin increased significantly less than SCC. In addition, peak level in late lactation was lower for cathelicidin (5.05-fold increase) than for SCC (7.64-fold increase). Twenty-one (5.8%) samples were positive to bacteriological culture, 20 for coagulase-negative staphylococci and one for Streptococcus spp.; 18 of them were positive to the cathelicidin ELISA (85.71% sensitivity). Sensitivity of SCC >500 000 and of SCC >1 000 000 cells/ml was lower (71.43 and 23.81%, respectively). Therefore, the high correlation of cathelicidin with SCC during the entire lactation, along with its lower increase in late lactation and good sensitivity in detecting intramammary infection (IMI), indicate a potential for monitoring subclinical mastitis in dairy goats. However, based on this preliminary assessment, specificity should be improved (40.41% for cathelicidin vs. 54.57 and 67.85% for SCC >500 000 and >1 000 000 cells/ml, respectively). Therefore, the application of cathelicidin for detecting goat IMI will require further investigation and optimization, especially concerning the definition of diagnostic thresholds.

The performance of a new point-of-care diagnostic (Mastatest), an on-farm test designed to identify bacteria and provide antibiotic sensitivity testing information from milk samples, was compared with standard microbiological culture methods. A total of 292 milk samples from clinical mastitis cases in dairy cows on New Zealand dairy farms were examined, and latent class analysis was used to estimate the performance characteristics of both tests. Two hundred and fifty-six samples (87.7%) demonstrated bacterial infection in standard culture, and 269 (92.1%) using the point-of-care diagnostic. The most common bacterial species detected was Streptococcus uberis, found in 195 samples (66.8%) using standard culture and 190 samples (65.1%) using the point-of-care diagnostic. Latent class analysis found no significant differences in test characteristics between the point-of-care diagnostic and standard culture. The estimated sensitivity and specificity of the point-of-care diagnostic against all targets combined were 94.6 and 72.1% respectively; the corresponding estimates for standard culture were 90.5 and 73.9%. Comparison of antibiotic susceptibility testing using the point-of-care diagnostic and the reference method showed similar trends and, in some cases, identical MIC50 and MIC90 values, with at most one antibiotic dilution difference.

The objective of this work was to evaluate the impact of changes during membrane filtration on the heat stability of milk protein concentrates. Dairy protein concentrates have been widely employed in high protein drinks formulations and their stability to heat treatment is critical to ensure quality of the final product. Pasteurized milk was concentrated three-fold by membrane filtration, and the ionic composition was modified by addition of water or permeate from filtration (diafiltration). Diafiltration with water did not affect the apparent diameter of the casein micelles, but had a positive effect on heat coagulation time (HCT), which was significantly longer (50 min), compared to the non diafiltered concentrates (about 30 min). UHT treatments increased the particle size of the casein micelles, as well as the turbidity of retentates. Differences between samples with and without diafiltration were confirmed throughout further analysis of the protein composition of the unsedimentable fraction, highlighting the importance of soluble protein composition on the processing functionality of milk concentrates.

Current available methods to detect cow milk adulteration or accidental contamination of goat milk are both laborious and time consuming. The aim of this technical research communication was to develop a simple, rapid, specific and sensitive method for quantitative detection of cow milk in goat milk. A competitive lateral flow immunoassay (LFIA) strip was developed using a specific monoclonal antibody (mAb) labeled with colloidal gold nanoparticles (GNPs) for specifically binding to cow milk casein. The detection limit of this rapid detection was 0.07% of cow milk in goat milk, providing equal specificity and higher sensitivity when compared with a commercial enzyme-linked immunosorbent assay (ELISA). These result suggest that the established rapid GNPs-LFIA strip could be used for monitoring cow milk adulteration/contamination of goat milk.

The objective of the work described in this research communication was to determine the lipoproteolytic capacity and potential of Pseudomonas spp. from the microbiota of refrigerated raw milk. The influence of temperature and bacterial population on these activities was also evaluated. Pseudomonas spp. (PS) counts (30 °C/48 h) were confirmed by PCR. Proteolytic (10% milk agar) and lipolytic capacities (PLC) (tributyrin agar) were evaluated (21 °C/72 h). Proteolytic (PP) and lipolytic potential (LP) were assessed by measuring the diameter of the halos and were categorized as low or high. A total of 91.3% PS possessed PLC. The PP of 64.16% isolates was high and was frequently observed in PS from milk samples with higher counts and lower temperatures. The LP of 70.52% isolates was low, and higher LP was associated with low microbiological counts and temperatures. Genetic studies evaluating Pseudomonas spp. strains in the milking environment and investigating the origin of these isolates could be useful to improve the quality and shelf life of dairy products.

Free fatty acid (FFA) concentrations can be elevated in raw milk due to improper handling and management at the dairy farm, and high concentrations of FFA can lead to off flavors in milk. This study aimed to describe how the herd production system, milking system, feeding and technological factors impact on FFA concentrations in bulk tank milk. FFA concentrations in bulk milk samples from 259 organic and 3326 conventional herds were analyzed by FT-IR during one year. The FFA content was significantly lower in bulk milk from organic than conventional herds. This was most evident during the summer half-year when the organic cows graze pasture. Bulk milk from automatic milking systems (AMS) and tie-stalls contained greater concentrations of FFA than any other milking parlor systems. In AMS, high milking frequency was found to be the most significant contributor to elevated FFA content in milk. Moreover, a strong interaction was found between milking interval and production system (organic vs. conventional). The technical factors, pre-cooling, onset time for cooling after milk inlet, contact between milk and agitation also impacted on the FFA concentration, whereas other technical factors including centrifugal pump type, length and height of pumping line and type of AMS manufacturer were found to be without significant effect on FFA. Feeding variables, based on feeding plans and evaluation, only explained a small part of the variation in bulk milk FFA. Overall, this study demonstrated that AMS compared to other milking system contributes significantly to increased FFA concentration in bulk tank milk, and within AMS high milking frequency contributes to increased FFA concentration.

With the aim to reduce the Na content, hard cheeses manufactured using the same technology as for Grana cheese (Grana-type) were salted using three brines containing different amounts of KCl (K-brines) and compared with control cheeses, salted with marine NaCl. A lower weight loss was observed in cheeses salted with K-brines (K-cheeses), whereas the yield and dry matter did not differ significantly between K-cheeses and controls. After 3 months of ripening (T3), the distribution of the Na cations (Na) was centripetal, with a higher Na concentration in the outer (0–3 cm of depth) layer, whereas the K cations (K) seemed to diffuse into the cheese more rapidly and homogeneously. Starting from the 6th month (T6), the distribution of both Na and K was stabilized through the different cheese layers. The use of the brine with the highest concentration of potassium (53.8% K) enabled us to successfully halve the Na content compared to the controls whereas, with the other brines, the reduction of Na was below 30%. At the end of ripening (T9), all the cheeses were without defects and the partial substitution of Na with K did not impact on the chemical composition, microbiological characteristics and ripening process. The sensory evaluation did not show any difference between K-salted and control cheeses in discriminant analysis.

A commercial drinkable yogurt with and without 4% of added trehalose (as cell protectant) was spray-dried obtaining a powder with low water activity (aw). Total bacterial count in the powder was between 8.48–8.90 log cfu/g. The dried yogurt was stored: (i) at 38 °C and aw = 0.33; (ii) at 38 °C in hermetically sealed flasks (aw = 0.21/0.22); (iii) in a cyclic temperature chamber (10–20 °C) in hermetically sealed flasks (aw = 0.21/0.22). Whole milk was then fermented by adding an inoculum of spray-dried yogurt after storage under these different conditions. The kinetics of acidification showed the presence of a lag time which was strongly dependent on storage conditions. The data was fitted with a logistic type equation from which the lag time was calculated. To evaluate structural differences among samples, Fourier Transform Infrared spectra (FTIR) were recorded. Partial Least Squares (PLS) models enabled a good correlation between lag time of fermentation and FTIR spectra. The lag time for yogurt powder stored at aw about 0.21/0.22 and cyclic temperature 10–20 °C remained approximately constant over the 12 weeks of storage, while all the other conditions resulted in a dramatic increase. The addition of trehalose had a small influence on lag time and, therefore, as a protectant of lactobacilli.

The aim of this Research Communication was to contribute to the knowledge of milk sialic acid concentration of bovines with specific focus on India. Sialic acids (SA) are important constituents of mammalian milks. Buffaloes are the main milk producing species in India, therefore, our research focused on both cow and buffalo. Two Indian cattle (Bos indicus) breeds (Sahiwal, Tharparkar), one cross bred cattle – Karan Fries (Tharparkar × Holstein Friesian) and a buffalo breed (Murrah) were selected. Systematic comparisons of the total, free and bound form of SA and also its distribution over the course of lactation- colostrums and mature milk (120–140 d) was generated. Animal management, sample collection and methodology of SA estimation were identical for the different groups. Colostrum had the highest concentration of SA, which declined with the progress of lactation in all the groups. Majority of the SA existed in bound form. No significant (P < 0.05) difference was recorded in the total, bound or free SA across all the groups. However, differences were obvious in the total and bound SA level in the mature milk. Indian cattle, Sahiwal and Tharparkar were equivalent, but had higher concentration of total and bound SA than crossbred cattle. Milk of buffalo had SA equivalent to that of crossbred cattle. The mean (se) levels of total SA was 23.4 (0.8), 25.8 (2.4), 20.3 (0.6) and 20.2 (1.2) in Sahiwal, Tharparkar, cross bred and Murrah buffalo, respectively. The findings suggested that milk of indigenous cattle may be a potential source of SA, a bioactive compound with beneficial effect on human health and a potential functional ingredient in foods. Results add value to the currently declining indigenous cattle of India.

In this Research Communication we evaluate the fatty acid (FA) profile of Wallachian sheep milk. The study was performed on 38 ewes in Beskydy Mountains. Samples were collected 4 times during the lactation, at monthly intervals. FA profile as well as groups of saturated, monounsaturated (MUFA), and polyunsaturated (PUFA) FAs were investigated. Considerable increase over the lactation was detected for lauric, myristic, myristoleic and palmitic acids, while stearic acid showed the opposed tendency. Variability, supported by significant differences among particular days of milk collection, was demonstrated for oleic acid; its highest distribution occurred at the beginning and at the end of the trial. The highest distribution of CLA was at the second sample day. Milk of Wallachian sheep naturally grazed at permanent pasture areas showed higher content of PUFA and MUFA in contrast with intensive or semi-intensive sheep breeds reported in the literature.

The objective of the studies reported in this research communication was to investigate the use of whey contaminated with antibiotics such as cephalosporins, quinolones and tetracyclines as a nutrient medium for the growth of Kluyveromyces marxianus with particular attention to the effect of thermal treatment used to overcome the inhibitory effects of antibiotic concentrations close to the Maximum Residue Limits. The heat treatments at 120 °C for 40 min, 120 °C for 83 min, and 120 °C for 91 min caused total inactivation of cephalosporins, tetracyclines and quinolone residues in whey respectively.

The work described in this Research Communication concerns the production of Dulce de leche (DL), that is a traditional product from South America obtained by concentration. Maillard reaction (MR) products are mainly responsible for the formation of color and flavor in this product. Lactose-hydrolyzed products have been developed to supply consumer demand, but this hydrolysis may affect the flavor, color, taste, texture and even some nutritional aspects of the product. We studied the influence of different levels of lactose-hydrolysis, sucrose addition and initial pH on the development of MR, appraised by the determination of 5-hydroxymethylfurfural (HMF). A process simulator with multi-monitoring system was used to produce 15 DL. Box-Behnken 33 experimental design was applied for the three factors: pH, lactose-hydrolysis level and sucrose concentration. Lipids, protein, ashes, carbohydrates, water activity, dissolved solids, colorimetric analysis and HMF (free and total) are among the physicochemical attributes and MR indicators analyzed in this work. The products showed significant differences in composition but all the values were in agreement with the literature. Moreover, higher levels of lactose hydrolysis and higher pH presented a direct relation with the development of MR, observed by an increase in coloration (lower luminosity) and more formation of HMF, both free and total. The present study expands the knowledge about DL spread made of lactose-hydrolyzed milk, allowing the food industries to produce a lactose free DL with nutritional and sensory characteristics closer to the traditional product.

This research paper addresses the hypothesis that the fortification of goat milk base with whey protein concentrate (WPC) could affect both the textural and the biofunctional properties of set-style yoghurt. The effect of fortification of goat milk base with two different WPCs on thermophilic bacteria counts, proteolysis, physical and biofunctional properties of set-style yoghurts was studied at specific sampling points throughout a 4-week storage period. Fortification and storage did not influence thermophilic counts. Physical properties were affected significantly (P < 0.05) by the composition of the protein and the mineral fraction of the WPC but not by the storage. ACE-inhibitory activity was moderate in accordance to low lactobacilli counts and lack of proteolysis. DPPH-radical scavenging activity, Fe2+-chelating activity and superoxide scavenging activity were high. At 28 d an anti-inflammatory effect was observed, which was not affected by WPC addition.

The process of agglutination causes firm cream layers in bovine milk, and a functioning agglutination mechanism is paramount to the quality of non-homogenized milks. The phenomenon is not well-described, but it is believed to occur due to interactions between immunoglobulins (Ig) and milk fat globules. For the first time, this paper demonstrates how the process of agglutination can be visualized using confocal laser scanning microscopy, rhodamine red and a fluoresceinisothiocynat-conjugated immunoglobulin M antibody. The method was used to illustrate the effect on agglutination of storage temperature and pasteurization temperature. Storage at 5 °C resulted in clearly visible agglutination which, however, was markedly reduced at 15 °C. Increasing storage temperature to 20 or 37 °C cancelled any detectable interaction between IgM and milk fat globules, whereby the occurrence of cold agglutination was documented. Increasing 20 s pasteurization temperatures from 69 °C to 71 °C and further to 73 °C lead to progressively higher inactivation of IgM and, hence, reduction of agglutination. Furthermore, 2-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that changes in storage temperature caused a redistribution of Ig-related proteins in milk fat globule membrane isolates. Poly-immunoglobulin G receptor was present in milk fat globule preparations stored at cold (4 °C) conditions, but absent at storage at higher temperature (25 °C). The findings provide valuable knowledge to dairy producers of non-homogenized milk in deciding the right pasteurization temperature to retain the crucial agglutination mechanism.

The aim of this work was to examine the effect of modified atmosphere packaging on the physicochemical and microbiological changes of Graviera Agraphon cheese during refrigerated storage. Blocks of Graviera Agraphon cheese weighing around 200 g were packaged under natural (control) or modified atmosphere packaging (MAP) conditions (50% N2 – 50% CO2) and stored at 4 °C or 10 °C for up to 85 d. Prior to packaging, groups of cheese blocks were inoculated with one each of the following foodborne pathogens at around 104 log cfu/g: Listeria monocytogenes, Salmonella Typhimurium, Escherichia coli O157:H7 or Staphylococcus aureus, whilst further groups of cheese blocks were not inoculated. The protein, fat, moisture and salt contents as well as the pH of control and MAP cheese samples did not change significantly (P > 0.05) throughout 4 °C storage, while the pH values of control and MAP cheese samples were significantly (P < 0.05) reduced at 10 °C storage. At 10 °C storage, yeasts and molds, psychrotrophs and lactic acid bacteria (LAB) were significantly higher (P < 0.05) for the normal atmosphere than the MAP cheese samples after the 4th, 8th and 4th days, respectively. At 4 °C storage, the yeasts and molds or psychrotrophs were significantly higher (P < 0.05) than those of control after the 6th and 15th days, respectively at 4 °C storage. All foodborne pathogens showed a higher decrease (P < 0.05) at 10 °C than 4 °C storage. S. aureus proved more sensitive in inactivation in the MAP conditions than atmospheric conditions. L. monocytogenes and S. aureus presented a higher decrease than that of E. coli O157:H7 and S. Typhimurium. In conclusion, MAP proved efficient in retarding the growth of yeasts, molds, psychrotrophs and E. coli O157:H7, L. monocytogenes, S. Typhimurium and S. aureus in Graviera Agraphon cheese during refrigerated storage at 4 and 10 °C.

This Research Communication describes the adaptation and testing of an RP-HPLC method, previously tested for the determination of lactoferrin (LF) in whey, for its applicability to determine milk lactoferrin content. Milk samples of various species, namely, ovine, caprine, bovine, donkey and human milk, were tested. The advantage of this RP-HPLC method includes speed and convenience, as it does not include extensive pretreatment or separation steps. A simple pre-treatment step was added in order to remove fat and proteins of the casein family and the samples were tested. The results varied in terms of elution of the LF peak both between the milk of the different species as well as from the initial application on whey. The peak resolution was satisfactory in the cases of ovine, bovine and donkey milk samples while for caprine and human milk an interference with other peaks was observed. Nevertheless, quantification of LF was found possible for all samples. This new application of the modified method will allow the determination of LF in milk samples of the tested species either for everyday analysis or as a useful qualitative screening for presence or absence of LF.

This research paper aimed to evaluate the role of inulin as a fat replacer on the quality of Frescal sheep milk cheese. Sheep milk and its derivatives are a promising niche in the dairy industry, mainly due to increasing interest of consumers in diversified products. Three Frescal sheep milk cheese formulations, namely whole milk cheese (WMC), semi-skimmed cheese (SSC) and semi-skimmed cheese with 5 g/100 g inulin (SSCI) were prepared. Their composition was evaluated and the feasibility of using inulin as a fat substitute was investigated. SSC and SSCI were considered ‘reduced fat’ or ‘reduced calorie’ products. The addition of inulin to SSCI cheeses yielded textural parameters (firmness, adhesiveness, cohesiveness, and gumminess) with intermediate characteristics between SSC and WMC. All the formulations presented scores higher than 7.6 in sensory analysis. In conclusion, the use of inulin in semi-skimmed sheep cheese allowed the production of cheese with texturizing properties similar to whole milk sheep cheese, enabling the development of a foodstuff with lower caloric content and beneficial characteristics valued by consumers.