Preservation Of Milk Research Articles

Investigation of concentration of thiocyanate ion in raw cow’s milk from China, New Zealand and the Netherlands

Thiocyanate ion is a natural component of cow’s milk (hereinafter as milk) which may be artificially augmented to activate the lactoperoxidase milk preservation system. This study presents a survey of thiocyanate levels in raw milk and proposes a naturally occurring baseline concentration of thiocyanate in milk, which is the basis for market supervision. 1669 raw milk samples from China, 270 samples from New Zealand and 120 from the Netherlands were collected in the survey. 65% of the samples contained thiocyanate above the detection limit. The average concentration of thiocyanate was 2.11mg/kg (0.10–16.20mg/kg). Differences in the concentrations of thiocyanate were found among three countries, the 12 selected provinces in China, and between summer and winter. The baseline concentration of thiocyanate found in raw cow’s milk was statistically calculated and rounded to 9.0mg/kg. Thiocyanate in milk at this level does not present a food safety concern.

Mode of action of leucocin K7 produced by Leuconostoc mesenteroides K7 against Listeria monocytogenes and its potential in milk preservation.

To investigate the mode of action of leucocin K7 against Listeria monocytogenes and to assess its inhibitory effect on Lis. monocytogenes in refrigerated milk. A bacteriocin-producing strain, Leuconostoc mesenteroides K7, was isolated from a fermented pickle. The bacteriocin, leucocin K7, exhibited antagonistic activity against Lis. monocytogenes with an MIC of 28µg/ml. It was sensitive to proteaseS and displayed good thermal stability and broad active pH range. Leucocin K7 had no effect on the efflux of ATP from Lis. monocytogenes but triggered the efflux of K(+) and the intracellular hydrolysis of ATP. It also dissipated the transmembrane electrical potential completely and transmembrane pH gradient partially. It 80 AU/ml inhibited the growth of Lis. monocytogenes by 2.3-3.9 log units in milk; when combined with glycine (5mg/ml), it completely eliminated viable Lis. monocytogenes over 7days Leucocin K7 shows different mode of action from nisin and may have potential application in milk preservation.

Do Milk Samples Stored for 12 Days after Collection Exhibit a Change in Composition Related to the Initial Bacterial Load?

Total bacterial count (TBC) is a tool used to assess milk quality and is associated with not only the initial sample contamination but also the sample storage time and temperature. Several countries have reported milk samples with a high TBC, and the influence of TBC on milk preservation remains unclear. Thus, the aim of this study was to evaluate the impact of the initial bacterial contamination level on the macrocomponents and somatic cell count (SCC) of raw milk samples preserved with bronopol and maintained at two storage temperatures (7 and 25°C) for up to 12 days. Thus, we collected milk samples from 51 dairy farms, which were divided into two groups according to the initial bacterial load: low TBC (<100,000 CFU/ml) and high TBC (≥100,000 CFU/ml). We analyzed the sample composition for protein, fat, total solids, lactose, milk urea nitrogen, and the SCC. We did not observe an effect from TBC and storage time and temperature on the concentration of protein, fat, total solids, and lactose. SCC changes were not observed for samples maintained under refrigeration (7°C); however, samples maintained at room temperature (25°C) exhibited a decrease in the SCC beginning on day 6 of storage. For milk urea nitrogen, values increased when the samples were maintained at room temperature, beginning on the ninth storage day. Samples with the preservative bronopol added and maintained under refrigeration may be analyzed up to 12 days after collection, regardless of the milk microbial load.

Antimicrobial and physico-chemical effects of essential oils on fermented milk during preservation

Objectives: Milk and milk products are known to be the good media for development of many microorganisms. Some essential oils are known to have antimicrobial activities against bacteria, mould and fungi. With the aim of contributing to the preservation of the fermented dairy products, the present study explored the use of essential oils for biopreservation in food pathogen control. The objectives were to study the effect of two essential oils extracted from local plants Xylopia aethiopica (Dunal) A.Rich. and Pimenta racemosa (Mill.) J.W. Moore on the physico-chemical, microbiological and organoleptic characteristics of the fermented milk. Methodology and Results: At the first level, essential oils were extracted from the leaves of plants and the minimum inhibitory concentration (MIC) of each one was detected using the serial dilution method and Muller Hinton Broth medium. The references strains used were Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922. Based on the MICs determined, essential oils were added to fermented milk and determination of its physicochemical characteristic, evolution of the microbial flora (meophilic flora, lactic flora, coliforms, Staphylococcus aureus ) were done during two weeks of preservation. The results showed that Xylopia aethiopica had a lowest minimum inhibitory concentration. After fifteen days of preservation, a decrease of mesophilic flora and lactic bacteria was observed and a disappearance was noticed for coliforms, thermotolerant coliforms and Staphylococcus aureus during the same time. These results prove the efficiency of those essential oils in fermented milk preservation. Moreover, microorganisms’ inhibition was more pronounced with Xylopia aethiopica essential oil than the Pimenta racemosa one. Conclusion and applications of findings: The study results showed a possible way of using essential oils as an alternative to chemical additives used for preservation of food products. As there are natural products, there could take an important part in the food safety policies. Keywords: Essential oils, biopreservation, fermented milk

A non-enzymatic sensor based on the redox of ferrocene carboxylic acid on ionic liquid film-modified screen-printed graphite electrode for the analysis of hydrogen peroxide residues in milk

Globally, the use of hydrogen peroxide (H2O2) for the preservation of raw milk has a long established history. However, in the EU, US and most parts of the world, where access to refrigeration facilities is widely available, the adulteration of milk with H2O2 is generally not permitted. An in-house hand-printed carbon electrode consisting of graphite printing ink modified with the room temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]), ferrocene carboxylic acid (Fca) and cellulose acetate (CA) for the electrochemical sensing of H2O2 in commercially packaged aseptic milk is described. The developed electrode successfully enabled sensitive determination of H2O2, free from interference from some known electroactive species such as ascorbic acid (AA), dopamine (DA), glucose and uric acid (UA). The linear range for the determination of H2O2 was 1.0μM–1.2mM with a limit of detection of 0.35μM and a sensitivity of 10.6nAμA−1μM−1cm−2. When used for the analysis of H2O2 residues in milk samples, the resulting precision (n=6) and recovery were 0.53% and 97.8%, respectively.

Short communication: Inhibitory activities of the lantibiotic nisin combined with phenolic compounds against Staphylococcus aureus and Listeria monocytogenes in cow milk

We aimed to investigate the antibacterial activities of carvacrol, thymol, eugenol, cinnamaldehyde, and lantibiotic nisin against standard bacterial strains of the milk pathogens Staphylococcus aureus ATCC 25923 and Listeria monocytogenes ATCC 15313 in cow milk. The minimum inhibitory concentrations (MIC) of these substances were recorded. The synergistic effects were also assessed in culture medium (time kill curve) and in a food model (cow milk) during the storage period (4°C for 6 d) after inoculation with S. aureus and L. monocytogenes individually by combining nisin and the phenolic compounds at proportions of 1/4 + 1/4 the MIC (determined in a previous in vitro assay) in the culture medium and 1/4 + 1/4 of MIC in the food model. Inhibitory activities of nisin and the tested compounds, as well as synergism in the combinations, were found against both bacteria assayed. Bacteriostatic effects were found with all combinations and a significant difference in L. monocytogenes reduction was found compared with the control assays. Thus, the antibacterial activity of nisin combined with phenolic compounds was confirmed against these pathogenic bacteria that are important in the milk industry, or more broadly in food science, with potential applications for milk preservation.

Change in viable bacterial count during preservation of milk derived from dairy cows with subclinical mastitis and its relationship with antimicrobial components in milk.

The objectives of the present study were to investigate the change in the number of viable pathogens during preservation of milk obtained from cows with subclinical mastitis and the association between the decreasing ratio of viable bacteria during preservation and the somatic cell count (SCC) and the values of lingual antimicrobial peptide (LAP), lactoferrin (LF) and lactoperoxidase (LPO). After preservation of milk at room temperature for 0, 0.5, 1, 2, 3, 4 and 5 hr, the bacterial colonies in the milk were counted to determine the number of colony forming units (CFUs). Fresh skim milk was used to determine the values of LAP, LPO and LF. Bacteria were not detected in 19.4% of milk samples, and this percentage increased up to 30% after 5 hr of preservation. The number of Staphylococcus aureus and Streptococcus uberis in milk did not change significantly during the 5-hr incubation, whereas significant decreases were observed in the number of coliforms, coagulase-negative staphylococci, yeasts and Corynebacterium bovis. High SCC significantly decreased CFUs of S. aureus and yeast after preservation of milk for 4 to 5 hr. High LF concentration in milk was associated with decrease in CFU of S. aureus during 4-hr preservation. These results suggest that the viable counts of some pathogens in milk decreased during preservation at room temperature after collection, which may be attributed to the leukocytes and antimicrobial components present in milk.

Thermal performance of milk chilling units in remote villages working with the combination of biomass, biogas and solar energies

The milk processing and preservation is a fast growing business in developing countries and it is facing problems due to high energy cost and environmental concerns in using conventional energy sources. The energy tapped from renewable energy sources through the technological innovations would be one of the best options to implement the milk preservation strategies at village level. In rural areas, bioenergy is one of the most versatile energy-generating options. Because of the diversity in feed stock and conversion technologies, suitable study is needed to implement renewable energy base technologies to provide a continuous flow of energy services. In this paper, the use of locally available renewable energy sources, in various combinations, to operate a milk chilling plant at village level has been analysed using the Matlab software. The effect of variations in the combination of renewable energy sources on the overall system COP has been studied. The study predicts that the best possible overall system COPs in hilly, rubber cultivation, paddy and seashore regions are 0.26, 0.25, 0.235 and 0.24 respectively. Moreover, suitable combinations identified in the aforementioned regions are Biomass/Gobar gas (0.7:0.3), Biomass/Biogas/Gobar gas (0.7:0.1:0.2), Biogas/Biomass/Gobar gas (0.6:0.15:0.25) and Biomass/Gobar gas/Biogas/Solar (0.5:0.25:0.125:0.125) respectively.

Performance characterisation of a small milk cooling system with ice storage for PV applications

The presented work proposes a calculation method to estimate the transient performance of a small on-farm milk cooling system for PV applications. The system employs 3 kg ice for fast cooling of 17 L milk in conventional 20-L-milk-cans. Two units of a commercial DC refrigerator operate at −10 °C and at 4 °C for ice production and milk preservation respectively. The development of milk temperature and energy consumption during a cooling event was studied experimentally at different ambient temperatures of 20 °C, 30 °C and 40 °C. A computational model was developed and validated where thermal resistances and COP were adjusted with experimental data. The results between 20 °C and 40 °C ambient temperature show a COP reduction of around 30% and a total daily energy consumption increase of around 100%. The specific total energy consumption of the system per litre milk was between 30 Wh/L and 58 Wh/L for the studied ambient temperature range. The suggested model can be used for the optimisation of photovoltaic stand-alone systems at specific locations.

Evaluation of nutritional quality, contamination, adulteration and preservative quality of different sources of milk

The present study was conducted at Dairy Science laboratory of Chittagong Veterinary and Animal Sciences University to evaluate nutritional quality, contamination, adulteration and preservative status of different sources of fluid milk. Milk samples were collected from farm, vendors and departmental stores. Test performed to evaluate the milk samples were chemical (% of butter fat, solids-not-fat and protein), added preservatives, adulteration status and microbial population (standard plate count, coliform and salmonella count). Results indicate that available market milk irrespective of brand maintaining the Bangladesh Standard Testing Institute (BSTI) standards as far as butter fat, solids- not-fat, protein and microbial quality is concerned. The nutritional and microbial quality of farm produced milk (FPM) was good except high coliform count. The nutritional and chemical quality of FPM and market milk (MM) of all five brands were satisfactory but vendors supplied milk was below standard due to water adulteration. Microbial quality of MM of all five brands was very safe for human consumption. High fat content even after watering and presence of formalin in 8% samples of vendor supplied rural milk (VSRM) indicates evening milk of previous day might be mixed with morning milk of next day. It may be concluded that these adulterants and preservatives in milk may cause severe public health related problems.

Practice of giving exclusive breastfeeding among the babies of working mothers and house wife mothers- a comparative study

Objectives : There is gradual reduction of exclusive breast feeding practice as age advances from birth to 6 months. The aim of the study was to see the status of exclusive breast feeding up to 6 month of age, among the babies of working mothers and housewife mothers and also to see different contributing factors among the working mothers for the initiation of breast milk substitute within this period.Material and Methods : This is a descriptive type of study conducted in Ad- Din Hospital at OPD from 1st January 2008 to 31st December 2009.Total 400 babies were selected, among them 200 were the babies of the working mothers, considered as cases and 200 were the babies the of housewives considered as control. Sampling was done purposively. Then babies of working mothers were divided in to 2 groups according to their age- (Group-I –babies of 3 months±15 days and Group-II 6 months±15 days). Also babies of the housewife mothers were also divided in to 2 groups (Group-I II–babies of 3 months±15 days and Group-IV 6 months±15 days). Each group includes 100 babies. Mothers or caregivers of their babies were interviewed only once for the study with a set questionnaire.Results : Seventy eight percent (78%) working mothers were continued exclusive breast feeding up to 3 months±15 days but at the age of 6 months±15 days only 21% babies were continued exclusive breast feeding . On the other hand at the age of 3 months ±15days 66% and at 6 months ±15days of age 45% babies of housewife mothers were continued exclusive breast feeding. Highly significant reduction of exclusive breastfeeding among babies of working mothers (p value&lt; 0.001) and also that of the housewife mothers (p value&lt;0.05). Significant number of mothers (more than 80%)of both the groups had no or inadequate knowledge about expression and preservation of breast milk (p value &lt;0.001 ). Maternity leave was less than 6 months, 4 months in government organization (GO) and even 45 days for in some non government organization (NGO) were observed.Conclusion : Exclusive breast feeding up to 6 months of age less among the babies of working mothers even with a good start. Lack of knowledge about expressed breast milk, policy adopted by the employers and maternity leave less than 6 months are the main contributing factors for reduction of exclusive feeding.Northern International Medical College Journal Vol.5(2) 2014: 339-341

CULTURAL IMPORTANCE OF CHEESE TYPE FOR KINGDOM PERNAMBUCANO

Cheese is one of the great achievements in the preservation of milk, using simple techniques and preserving important protein source in different food crops. Originally from the Netherlands, Edam cheese was introduced in Brazil in 1880 by the Portuguese colonizers, hence the name "kingdom." Currently, in the industrial production, the legislation determines that it is classified as "kingdom type ". Due to the high lipid and sodium content, this product that is most suitable in the composition of sandwiches, in sauces added to pasta and composition along with the desserts, these associations are part of the tradition, flavors and knowledge of Pernambuco’s cooking. A ball of Kingdom cheese is something that you have to give to families, especially in Christmas time and St. John, because it symbolizes the wish for happiness and prosperity in the northeastern important religious festivals calendar, where relatives and friends gather to celebrate the dates in question, putting on their tables this precious culinary heritage of Pernambuco.

Long-term Listeria monocytogenes proliferation control in milk by intermittently delivered pulsed electric fields, implications for food security in the low-income countries

Microbial density control is a major challenge for food preservation especially in the low-income countries, where 850 million undernourished people live. In this work, we report on non-thermal, chemical-free microbial cell density control by intermittently delivered pulsed electric fields (IDPEF). We show that IDPEF allows for precise control of L. monocytogenes density in contaminated milk, an essential product for small farmers in low-income countries. Using L. monocytogenes growth kinetics, we designed an IDPEF protocol that consists of 2 sequences of 10 square wave pulses, 50 μ s duration, 12.5 kV cm-1 electric field strength, delivered at 0.5 Hz and 1 min pause between the sequences applied every 1.5 hours. In a 12 hours experiment at 32 °C, L. monocytogenes density of untreated samples reached (9.1 ± 0.6) ⋅ 107 CFU ml-1 and (7.1 ± 0.3) ⋅ 108 CFU ml-1 for initial load of (1.4 ± 0.2) ⋅ 103 CFU ml-1 and (3.1 ± 0.3) ⋅ 106 CFU ml-1 respectively; the final density in the IDPEF treated samples, however, was 120 ± 44 CFU ml-1 and (1.1 ± 0.3) ⋅ 105 CFU ml-1. The energy required for IDPEF storage of milk in the low-income countries could be generated by a small-scale 2kW solar energy system operating 5.5 hours per day in combination with small-scale energy storage system. We believe that IDPEF storage technology can empower millions of small farmers in the low-income countries by providing them a simple and energy efficient technology for milk preservation.

Microbiological Evaluation of Ultra-High-Temperature (UHT)-Treated Milk Close to Expiry Date and Routine Home Practices for Preservation of Milk.

Background:As milk is an excellent medium for growth of microorganisms, milk gets contaminated very easily leading to its early spoilage and to milk-borne diseases.Objectives:To compare the quality of pasteurized milk with milk cooker-treated milk and to compare the quality of fresh ultra-high-temperature (UHT) milk with that of UHT milk close to expiry date.Materials and Methods:Samples of pasteurized milk, milk heated in milk cooker, fresh UHT milk, and UHT milk nearing expiry date were tested by methylene blue reduction test, coliform test, and colony count test. The results were analyzed statistically using Statistical Package for Social Sciences (SPSS) version 11.5.Results:All milk samples passed the methylene blue test and UHT-treated milk passed the coliform test also. Out of the 30 fresh pasteurized milk samples, seven (23.3%) passed the coliform test; but the same after milk cooker treatment, 16 (53.3%) passed the coliform test (P < 0.05). Fourteen (46.6%) out of 30 fresh pasteurized milk samples failed the colony count test, but the same after milk cooker treatment only eight (26.6%) failed the test (P = 0.583). Only seven out of the 60 UHT milk samples failed the colony count test and out of these six (20%) were close to expiry date (P < 0.05).Conclusions:Milk cooker-treated milk appears to be safer than the fresh pasteurized milk. Fresh UHT-treated milk is safer then UHT milk close to expiry date.

Human Milk Composition and Preservation: Evaluation of High-pressure Processing as a Nonthermal Pasteurization Technology

Human milk is seen not only as a food, but as a functional and dynamic biologic system. It provides nutrients, bioactive components, and immune factors, promoting adequate and healthy growth of newborn infants. When mothers cannot supply their children, donated breast milk is the nutrition recommended by the World Health Organization, as it is a better alternative than infant formula. However, because of the manner in which donor milk is handled in human milk banks (HMB) many of the properties ascribed to mother's own milk are diminished or destroyed. The major process responsible for these losses is Holder pasteurization. High-pressure processing (HPP) is a novel nonthermal pasteurization technology that is being increasingly applied in food industries worldwide, primarily as an alternative to thermal treatment. This is due to its capacity to inactivate microorganisms while preserving both nutritional and bioactive components of foods. This review describes human milk composition and preservation, and critically discusses HMB importance and practices, highlighting HPP as a potential nonthermal pasteurization technology for human milk preservation. HPP technology is described and the few currently existing studies of its effects in human milk are presented.

INTERPRETACE VÝSLEDKŮ POKUSNÉ KALIBRACE PRO STANOVENÍ KYSELINY CITRONOVÉ V MLÉCE INFRAČERVENOU SPEKTROSKOPIÍ (MIR-FT)

Citric acid (KC) in milk is indicator of cow energy metabolism. Milk laboratories set up KC determination. A method can be infra-red analyse (MIR-FT). The goal was to develop a relevant method for reference sample preparation for MIR-FT (indirect method, Lactoscope FTIR and MilkoScan FT 6000) calibration. As reference was used a photometric method (c; 428 nm). KC was added (n = 3) into some re­fe­ren­ce milk samples (n = 10, bulk milk). Mean value was 9.220 ± 3.094 mmol . l−1with variation range from 6.206 to 15.975 mmol . l−1. Recovery c was from 100.8 to 120.2 %. Correlation between c and ­MIR-FT were from 0.979 to 0.992 (P &lt; 0.001). These were lower in the set of native milk samples (n = 7), from 0.751 (Lactoscope FTIR; P &lt; 0.05) to 0.947 (MilkoScan FT 6000; P &lt; 0.001) in comparison to original va­lues from 0.981 to 0.992 (n = 10; P &lt; 0.001). Correlations between calibrated MIR-FT instruments were from 0.958 to 1.0 (P &lt; 0.001). Average recovery for instruments (n = 12) was 101.6 ± 18.1 %. The mean differences between c method and MIR-FT after calibration (n = 4) moved from −0.001 across zero to 0.037 %. Standard deviation of differences was from 0.0074 to 0.0187 % at MilkoScan FT 6000 and from 0.0105 to 0.0117 % for Lactoscope FTIR. Relative variability of differences (MIR-F (filter technology) and FT) for major components fat (T), proteins (B) and lactose (L) in total and minor components KC and free fatty acids (VMK) was estimated to 1.0 and 7.2 and 34.4 %. The KC result is inferior than T, B and L superior than VMK. Autocorrelation (0.042; P &gt; 0.05) of results demonstrated the in­de­pen­den­ce of consecutive measurements. Milk preservation effect amounted 0.2323 (P &lt; 0.001) with bronopol and 0.0339 (P &gt; 0.05) mmol . l−1with dichromate. It was (3.0 and 0.44 %) practically negligible, redeemable via relevant calibration. The results of proficiency testing in post-calibration period and evaluation of double transport stress effect samples (difference was −0.006 ± 0.071 mmol . l−1(P &gt; 0.05)) demonstrated the useability for central calibration system. Milk KC results of MIR-FT calibration were good and can be suitable for practical screening.

Innovative Approach on the Method of Producing Fresh Milk Cheese

The method of making fresh milk cheese with the use of alternative methods of milk preservation - the use of enzyme preparations with high basidial fungi is examined in the article. Milk coagulation activity of enzyme preparations derived from high basidial fungi - producers of protein milk action Hirschioporus laricinus (Karst.) Ryv. and Irpex lacteus was established by the Method Kawai, Mukai. It was established that the highest milk coagulation activity have enzyme preparations with strains A&Don&02 and P&04. It was defined that the concentration of calcium chloride solution needed as a catalyst for the process of milk coagulation. The new method of obtaining fresh milk cheese using enzyme.

Techno-economic studies on hybrid energy based cooling system for milk preservation in isolated regions

In developing countries like India, about 70% of the population is engaged in the production of milk, fruits and vegetables. Due to the lack of proper storage and transit facilities, the agricultural produce, in remote areas loses its value. This spoilage could be prevented at the local village level, by providing cooling units for short term preservation. In this paper, the possibility of a hybrid energy based thermally operated cold storage has been considered to meet the cooling needs of the villages in the southern parts of India, where biomass, biogas and gobar gas are available in abundance. A milk cooling system that uses various combinations of locally available renewable energy sources to operate an aqua ammonia vapour absorption cooling system has been analysed using the Matlab software. The impact of various combinations of renewable energy sources on the Coefficient of Performance (COP), Net Present Value (NPV) and payback period of the total cooling system has been studied. The analysis shows that the COP and payback period of the proposed hybrid renewable energy based milk cooling system are 0.16–0.23 and 4–6years respectively.

Vitamins, fatty acids, and antioxidant capacity stability during storage of freeze-dried human milk

Although freezing is the most common method used to preserve human milk, nutritional and immunological components may be lost during storage. Freeze-drying could increase the shelf life of human milk, while preserving its original characteristics. Seventy-two samples of freeze-dried human milk were stored for different periods of time, up to a maximum of 3 months, at 4 °C or 40 °C. Vitamin C, tocopherols, antioxidant capacity, and fatty acids composition were analyzed. A new HILIC–UHPLC method improving vitamin C determination was also validated. Ascorbic acid and total vitamin C concentrations significantly decreased at both temperatures, while antioxidant capacity only decreased at 40 °C. Fatty acids composition and both γ-tocopherol and δ-tocopherol contents remained unaltered. The stability after storage of freeze-dried milk was higher than that reported for frozen or fresh milk indicating that freeze-drying is a promising option to improve the preservation of human milk in banks.

Comparison of commercially‐available methods to preserve DNA in human milk (623.10)

Sequencing methods used to characterize the milk microbiome require that milk DNA content not change between time of collection and analysis. Although cold storage is optimal, chemical preservatives are needed when refrigeration is not available. The objective of this study was to test the efficacy of 4 commercially‐available preservatives ‐ RNAlater (RNAL, Ambion), Milk Preservation Solution (MPS, Norgen Biotek), DNAgard Saliva (SAL, Biomatrica), and Broad Spectrum Microtabs II (TAB, D&amp;amp;F Control Systems) ‐ in milk held at 37 °C for 6 wk. Aliquots of 8 pools of fresh human milk were treated with each preservative; DNA was extracted immediately and 1, 2, 4, and 6 wk later. DNA was quantified using the Qubit dsDNA HS Assay (Life Technologies). There was a treatment by week interaction (P&lt;0.05) on milk DNA content. After an initial decrease, DNA concentration of MPS‐treated milk remained constant, whereas that of milk treated with SAL, RNAL, or TAB did not change. However, more DNA was consistently extracted using MPS or SAL (P&lt;0.05) than with RNAL or TAB. In summary, preliminary evidence suggests MPS and SAL may be suitable to preserve DNA in milk for up to 6 wk at high ambient temperatures.