Milk Fat Fractions Research Articles

Novel milk fat fractions for health and functionality obtained by short-path distillation

Medium-chain fatty acids (MCFA) are associated with various health benefits, such as enhanced insulin sensitivity and reduced appetite. The study explored the potential of combining dry or solvent fractionation with short-path distillation (SPD) to obtain milk fat (MF) fractions enriched in MCFA. By using only SPD, a 2-fold increase in MCFA and an 18-fold increase in α-tocopherol in distillates was obtained compared to native MF. The distillate has a lower melting temperature than does MF. Pre-fractionation processes before SPD did not lead to an additional increase in MCFA. The study demonstrates the potential of SPD to produce MF fraction (distillate) with significant enrichment in MCFA, differed thermal behavior, and increased α-tocopherol content while keeping the FA composition and thermal properties of the remaining fraction (retentate) similar to MF as only 10% of the milk fat have been removed.

Reproduction of the technology for the production of “Rossiysky” cheese in laboratory conditions, depending on the quality of milk

Relevance. Dairy processing enterprises are expanding the range of dairy products with the introduction of production of various cheeses. Small producers have also become active in cheese production. In 2023, the decrease in the price and demand for raw milk had a particularly strong impact on collective (farmer) and personal subsidiary farms. This caused the need for milk processing in rural conditions. Our research is aimed at developing technology for the production of ”Rossiysky” cheese for peasants and farms.Methods. The Kjeldahl method determined the mass fraction of protein, acid method — the mass fraction of fat, calculated — the mass fraction of dry matter and skimmed milk residue, ultrasonic — the mass fractions of milk fat, protein, lactose, milk powder, skimmed milk residue, the amount of added water, mineral salts, density, freezing point, temperature, by the express method — active acidity.Results. The chemical composition and physico-chemical properties of raw milk were studied in winter and spring. It was found that the mass fraction of fat in milk reaches 4.31–4.65%. Mass fraction of protein is 2.92–3.02%. The ratio of milk fat to protein is 1.48–1.54, with the recommended norm being 1.1–1.25. Changes were made to the technological scheme for the production of “Rossiysky” cheese, taking into account the characteristics of the quality of milk and the equipment used in the conditions of peasants and farms. To obtain milk with the required protein to fat ratio, the mixture was normalized. “Rossiysky” cheese was produced from normalized milk. The quality of cheese in terms of organoleptic, physico-chemical and microbiological indicators meets the requirements of regulatory documents.

Effects of feeding whole-cracked rapeseeds, nitrate, and 3-nitrooxypropanol on composition and functional properties of the milk fat fraction from Danish Holstein cows

The aim of this study was to determine the individual and combined effects of supplementing fat (FAT), nitrate (NITRATE) and 3-nitrooxypropanol (3-NOP) on compositional and functional properties of milk fat. An 8 × 8 incomplete Latin square design was conducted with 48 lactating Danish Holstein cows over 6 periods of 21 d each. Eight diets were 2 × 2 × 2 factorially arranged: FAT (30 or 63 g crude fat/kg DM), NITRATE (0 or 10 g nitrate/kg DM), and 3-NOP (0 or 80 mg 3-NOP/kg DM) and cows were fed ad libitum. Milk samples were analyzed for general composition, fatty acids (FA) and thermal properties of milk fat. Milk fat content was decreased by FAT and NITRATE and increased by 3-NOP. The changes in FA composition were mainly driven by the FAT × 3-NOP interaction. FAT shifted milk FA composition toward lower content of saturated FA (SFA) and greater contents of mono- and poly-unsaturated FA (MUFA and PUFA), whereas these effects of FAT were smaller in combination with 3-NOP. However, 3-NOP had no effects on SFA, MUFA and PUFA in low fat diets. FAT lowered solid fat content in milk fat because of decreased SFA content. The onset crystallization temperature of milk fat was decreased by 3-NOP when supplemented in low fat diets. According to the FAT × 3-NOP interaction, supplementation of fat without 3-NOP shifted peak temperature of low melting fraction of milk fat toward low temperature as a result of decreased proportion of C16:0, and increased proportions of C18:1 cis-9, C18:1 trans-11, C18:2 cis-9, and CLA cis-9,trans-11. In conclusion, no additive effects were observed among FAT, NITRATE and 3-NOP on chemical and thermal properties of milk fat and fat supplementation largely changed milk FA composition and in turn affected the thermal properties of milk fat.

Определение взаимосвязи генотипов SNP с содержанием жирных кислот различной пространственной конфигурации в молоке коров

Abstract. Milk fat is the third main source of lipids for human nutrition. Fatty acids in milk fat have a heterogeneous composition due to differences in chain length, degree of saturation, etc. It has been scientifically proven that long-term consumption of trans-fatty acids causes various diseases of the human body; according to WHO recommendations, their maximum consumption should not exceed 1 % of total energy. A comprehensive study of the composition of fatty acids in cattle milk gives scientists the opportunity to use this trait in breeding work by selecting genotypes with a low content of trans-isomers and saturated fatty acids harmful to human health. The scientific novelty lies in the study of molecular genetic mechanisms for regulating the quantitative content of fatty acids and their trans-isomers in the fat fraction of cow's milk. The purpose of the work is to identify allelic variants of SNPs associated with the fatty acid composition of cow's milk and the content of trans isomers of unsaturated fatty acids in it. Research methods. The studies were carried out on cows of the Holstein black-and-white breed. The genetic profile of animals of the Holstein black-and-white breed was studied, SNPs significantly associated with the quantitative and qualitative content of fatty acids and their trans-isomers in the fat fraction of cow's milk were identified. The fatty acid composition of cows' milk was determined using a multiparameter automatic analyzer MilkoScan 7/Fossomatic 7 FT+ / DC (FOSS, Denmark). Results. Whole-genome genotyping was performed. Analyzing the content of fatty acids with different saturation of hydrogen bonds, a significant difference between the amount of fatty acids and genotypes, reliable values were established only for 5 SNPs. It was found that for four SNPs, the highest values of the content of fatty acids and trans-isomers were in homozygous genotypes ARS-BFGL-NGS-41348GG; BTA-115852-no-rsAA; BTB-00771463GG; Hapmap46159-BTA-70956TT. A significant difference in the content of trans-fatty acid isomers in milk between genotypes was found only for SNP ARS-BFGL-NGS-5502. The largest mass fraction of trans-isomers of unsaturated fatty acids was found in the milk fat of cows with the heterozygous genotype AG, which amounted to 0.076 g/100 g and was 0.011 g/100 g and 0.032 g/100 g (P≤0.01) more compared to heterozygous genotypes GG and AA, respectively.

ХИМИЧЕСКИЙ СОСТАВ И ТЕХНОЛОГИЧЕСКИЕ СВОЙСТВА МОЛОКА КОРОВ-ПЕРВОТЕЛОК ПРИ РАЗНЫХ СПОСОБАХ СОДЕРЖАНИЯ И ТЕХНОЛОГИЯХ ДОЕНИЯ

Industrial milk production is based on high-tech processes at the current stage. Strong requirements imposed on milk quality are due to the quality of raw materials for producing a wide range of dairy products. The production of milk that meets sanitary and hygienic standards and the requirements of regulatory and technical documents (regulations and standards) is a priority in dairy cattle breeding. Analysis of the chemical composition of milk obtained from the control and experimental groups showed that the milk fat content was the highest (4.06 %) in the 1st experimental group and exceeded the control (3.93 %) and the 2nd experimental (3.94 %) groups. Under the loose housing system the mass fraction of protein was 3.15 %; the value was 0.02 points larger compared with the tie housing system. The milk density in the animal groups ranged from 1027.0 to 1029.0 kg/m3 , which meets the requirements of GOST 31449-2013. The largest mass fraction of dry solids in milk was found in the 2nd experimental group (12.58 %). The data analysis indicates that the housing system type and the milking technology of first-calf heifers have an effect on the number of milk fat globules per 1 cm3 and their diameter. The analysis of the quantitative and qualitative composition of fat globules has provided more complete data about the milk fat fraction, which is a crucial index in milk production. The milk obtained from the Holstein breed heifers in the studied groups can be used for cheese making. The third yogurt sample had a milky white colour, homogeneous throughout the mass; the consistency was homogeneous, with good curd tension and low viscosity; the sample had a pure, fermented milk flavour, without foreign traces.

Crystal networks, partial coalescence, and rheological properties of milk fat fraction model systems

This study aimed to investigate the crystal network of bulk milk fat fractions and the partial coalescence, and the rheological properties of their oil-in-water (O/W) emulsions. Different milk fat fraction model systems were compared for their physicochemical properties, crystallization kinetics, and fat crystal networks across a range of temperatures. The extent of partial coalescence and rheological properties of the O/W emulsion prepared by different milk fat fractions were further analyzed. The results demonstrated that the ratio between saturated fatty acids (SFA) and unsaturated fatty acids and triacylglycerides (TAG) influenced the melting thermal behaviors, solid fat contents (SFC), and crystal networks of various milk fat fractions, which in turn influenced the partial coalescence and rheological characteristics of their O/W emulsions. Moreover, an excellent fit of the trend line confirmed that hardness increased exponentially with SFC. Trisaturated TAG in fractions with high melting points (HMF) such as milk fat fraction MF45, whose clarification temperature was 45°C, enriched long-chain SFA (saturated:unsaturated fatty acid= 2.2:1). We found that MF45 achieved higher SFC and hardness in the range of 0 to 40°C and, ultimately, formed a well-defined microstructural network with thick, rod-like crystals. Further, TAG in fractions with low melting points (LMF) such as MF10, whose clarification temperature was 10°C, were enriched with short-chain and unsaturated fatty acids (saturated:unsaturated fatty acid = 1.5:1), and a disordered crystal network in MF10, composed of randomly arranged, translucent platelets, was detected. Although fat globules of HMF and LMF were stabilized against coalescence, this could be attributed to a variety of mechanisms involving SFC, liquid fat, protective film around the fat globule, and minor lipids. According to the rheological profiles, all O/W emulsions exhibited weak viscoelastic "gel-like" structures [storage modulus (G') > loss modulus (G")] over most of the measured range. The G' values and apparent viscosity of HMF were greater than those of other fractions, indicating that the large and rigid crystals strengthen the networks more effectively.

Decoding the role of triacylglycerol composition in the milk fat crystallisation behaviour: A study using buffalo milk fat fractions

The role of triacylglycerols (TAGs) composition in milk fat crystallisation is evaluated from a new perspective by correlating the crystal structures and their predicted TAG contributors. Four different TAG groups, defined by their fatty acid (FA) chain length and saturation are proposed to explain the crystallisation behaviour of different milk fat samples, namely TAGs containing (i) fully saturated long chain FAs, (ii) single unsaturated long-chain FA and (iii) multi unsaturated long-chain FAs, as well as (iv) short-chain FAs. Samples containing different TAGs proportions were obtained from two-step dry fractionation of buffalo milk fat. Liquid chromatography and mass spectrometry (LCMS) was employed to determine the TAGs composition. The crystallisation characteristics were evaluated using small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) and polarised light microscopy. The results confirm that fully saturated long chain TAGs are responsible for the formation of high melting point 2L-crystals (d-spacing: 44.1–49.7 Å), whilst the low melting point 3L-crystals (64.4–72.8 Å) are mainly contributed by long chain TAGs containing unsaturated fatty acids. Further, the crystallisation inhibiting effect of asymmetrical TAGs, containing short chain fatty acid (C4-6) is evident. As a final point, effects of the four TAG groups, each given with a specific composition, were examined closely also with respect to their influence on the nucleation and polymorphic transformation kinetics of milk fat crystals.

Changes in the Qualitative Composition of the milk of Holstein Cows During Summer Chronic Heat Stress

Seasonal summer heat stress leads to significant economic losses, resulting in a drop in milk yield in dairy cows and a deterioration in milk quality. The purpose of this study was to determine the changes in some qualitative parameters of milk in Holstein cows during chronic heat stress on one of the largest commercial dairy farms Ukraine (50°49′14″ N, 31°49′23″ E). Five multiparous cows of medium lactation with a milk yield of about 30 kg per day were randomly selected into the reference (in the spring, at the end of May) and the experimental group (in the summer, at the end of August). Milk samples were taken from cows during the morning milking. Qualitative analysis of milk included the identification of milk solids-not-fat, density, mass fraction of lactose, fat, protein and minerals, as well as the freezing point, electrical conductivity and active acidity using ultrasonic method. Animals were kept in naturally ventilated barns. The total mixed single-type balanced diet consisting of corn silage and concentrates that the cows received remained unchanged. The sampling of milk from cows of the experimental group was preceded by a continuous 26-day hot period, during which the maximum daily values of the temperature and humidity index did not fall below 72 units. The results showed that in the milk of the animals of the experimental group there was a significant decrease in the content of milk solids-not-fat, the mass fraction of fat and protein (P0.05). The mass fraction of lactose and minerals tended to increase. It should be noted that the average daily milk yield of dairy cows in the herd in spring and summer was almost at the same level. In conclusion, the results of the study showed that high summer temperatures lead to a deterioration in the quality of milk in Holstein cows. Despite the decrease in milk density and freezing point, these figures met the requirements of the standard. Organoleptic indicators of milk, electrical conductivity and active acidity of milk did not change in hot weather, their value indicated the naturalness of milk. The mass fraction of milk fat, which undergoes the greatest change under the influence of seasonal heat stress, is one of the most valuable components of milk, which has a direct effect on nutritional value and purchase price of raw milk. Therefore, a further deeper study of the fatty acid composition of milk using the method of chromato-mass spectrometry will provide valuable data necessary to search for possible herd management strategies to maintain high milk quality under conditions of seasonal heat stress.

Fatty acid, triglyceride, and kinetic properties of milk fat fractions made by the combination of dry fractionation and short-path molecular distillation

In this study, we aimed to detect the physicochemical properties of distilled products (residue and distillate) obtained from anhydrous milk fat (AMF) and its dry fractionation products (liquid and solid fractions at 25°C (25 L and 25 S)). The results showed that the saturated fatty acids and low- and medium-molecular-weight triglycerides were easily accumulated in the distillate, and the percentage of unsaturated fatty acid and high-molecular-weight triglycerides in the residue were higher, and these components in 25 S and 25 L were influenced more significantly than those in the AMF. In addition, the distillate had larger melting ranges in comparison with the distilled substrate, while the melting ranges of residue was smaller. The triglycerides were presented as the mixture crystal forms (α, β', and β crystal) in 25 S, AMF, and their distilling products, and it was transformed gradually to a single form as the increasing of distilling temperature. Moreover, the accumulated pattern of triglycerides was double chain length in 25 S, AMF, and their distilling products. These results provide a new approach to obtain the MF fractions with different properties, and the findings of this study enrich the theoretical basis of MF separation in practical production.

The Influence of Cold-Pressed Linseed Cake Supplementation on Fatty-Acid Profile and Fat-Soluble Vitamins of Cows' Milk in an Organic Production System.

The aim of the study was to determine the effect of linseed cake supplementation during the winter period as a factor influencing the level of some bioactive components (milk composition, fatty-acid profile, and fat-soluble vitamins) in the milk fat fraction in cows kept on an organic farm. Forty multiparous (second and third lactation) Holstein-Friesian cows were selected that had 81 ± 12 days in milk and produced 15.08 ± 1.20 kg of milk/day. Two groups were created for the experiment: control (CTL; n = 20) and experimental (LC; n = 20). The experiment was divided into two periods: an initial period lasting 7 days in which the experimental group was habituated to the new supplement in their diet; the proper experimental phase, lasting 6 weeks, in which the cows in the experimental group received an individual daily dose of linseed cake (300 g/day/cow). Linseed cake supplementation had a positive impact on the levels of bioactive components (fatty-acid profile and fat-soluble vitamins) in the milk fat fraction. At the end of the trial, the concentration of C18:2 cis9 trans11, C18:1 trans11, α-retinol, α-tocopherol, and total antioxidant status increased 1.59-, 1.94-, 3.12-, 3.38-, and 3.09-fold, respectively, relative to the control levels. The use of linseed cake in winter on organic farms makes it possible to increase the antioxidant potential of milk, thereby eliminating the disparity in the quality of milk from the summer season compared to the winter season.

Fatty acid and triglyceride molecular species of milk fat fractionated by short‐path molecular distillation

SummaryFractionation is important for the application of milk fat (MF). In this study, the contents of fatty acid (FA) and triglyceride (TAG) of MF and its fractions distilled by short‐path molecular distillation (SPMD) were detected. The results showed that a total of 19 FAs and 109 TAG molecular species were detected. Moreover, the short‐chain saturated FA, medium‐chain saturated FA, low‐molecular‐weight TAG, medium‐molecular‐weight TAG, S3 (TAG molecular species with three saturated FAs) and L2S (TAG molecular species with two long‐chain FAs and one short‐chain FA) were easily accumulated in the distillate, and the percentage of these components all increased first and then decreased during the whole distilling process. Compared with the distillate, polyunsaturated FA (PUFA) and high‐molecular‐weight TAG (HMW‐TAG, with the carbon numbers: 41–54 and molecular weight: 704–888) were enriched in the residue, and the increasing ratio of PUFA and HMW‐TAG was 393.75% and 8.58% respectively. Further analysis showed that the 16:0/4:0/16:0, 16:0/4:0/14:0, 16:0/12:0/4:0, etc. were the discrepant TAG molecular species during SPMD. Therefore, these results demonstrated that different fractions of MF could be obtained by adjusting the fractionation temperature, and it also would provide more important theoretical guidance for regulating MF fractionation, enriching the nutritional information of MF fractions.

Gas Chromatographic Determination of Fatty and Organic Acid Composition in Selenium-Protein Dietary Supplement

Topicality. The use of selenium-protein dietary supplements (SPDS) is relevant from a medical and economic point of view, as it can provide consumers with the required amount of selenium, and increase the value and attractiveness of food products. The diet of a modern person is very diverse in the composition of fatty ingredients. Of all natural fats, dairy is the most complex and unique one in its chemical composition. SPDS “Syvoselen Plus” contains up to 10% fat in its composition, therefore, studies of its composition are of certain scientific interest in view of the above. In many scientific studies, gas chromatography is used to determine the composition of not only the fat fraction of additives containing vegetable oils and animal fats, but also organic acids. The study of the fat fraction and the fraction of organic acids of additives by this method allows determining and predicting the composition of similar fractions in the final product from SPDS. This, in turn, allows for comprehensive control of the quality and composition of such final products. The aim of the article is to determine the quantitative and qualitative composition of fatty and organic acids in the SPDS “Syvoselen Plus” by the gas chromatography method, and to compare the results of the determination with the indicators of a hypothetical ideal fat. When writing the article, statistical and physico-chemical research methods were used, namely, the gas chromatography method, with the help of which the following problems are solved: the composition of the fat fraction of SPDS is determined quantitatively and qualitatively; the degree of correspondence of the main indicators of the fat “Syvoselen Plus” to the hypothetical ideal is established; the composition of organic acids in the additive is determined. Results. The fatty acid composition of milk fat, milk whey and SPDS was studied. Dietary supplement “Syvoselen Plus” contains a significant amount of palmitic (3117.71 mg/kg), stearic (1618.61 mg/kg), oleic (1397.95 mg/kg) and meristic (1296.69) mg/kg) fatty acids, which is confirmed by chromatograms of fat fractions of milk fat and SPDS. The main indicators of hypothetically ideal, milk, whey fats and DDBS were presented. As a result, it was established that the composition of fat, which is most similar to the ideal one, among the objects of the study, has SPDS “Syvoselen Plus” (the indicator of the ratio of the sum of oleic and linoleic acids to the sum of pentadecanoic and stearic acids coincides with the indicator of ideal fat, and the indicators of the ratio of linoleic to linolenic acids and linoleic to oleic acids are close to the values of the indicators of ideal fat). The study of the composition of organic acids of SPDS was carried out. Fractions of succinic, azelaic, and levulinic organic acids are predominant, which may be due to the type of dairy products from which the serum was obtained, the storage conditions of dairy products and the serum itself, the type of microorganisms that carry out the fermentation process and can produce various organic acids, and the production process of dairy products and their composition. Conclusions and discussion. The analysis of the fatty acid composition and the quality content of organic acids in “Syvoselen Plus” dietary supplement confirmed the feasibility of using a dietary supplement in health food technologies, since the latter contains enough polyfunctional fatty and organic acids.

Effect of Protein Concentrates and Isolates on the Rheological, Structural, Thermal and Sensory Properties of Ice Cream

The possibility of using protein concentrates and isolates instead of milk solids-not-fat (MSNF) in the production of ice cream with a high mass fraction of milk fat (12%) and increased mass fraction of protein was investigated and justified in this article. The ice cream samples with use of milk protein concentrates (MPC), whey protein concentrates (WPC), milk protein isolates (MPI) and native whey protein isolates (NWPI) were made according to classical technology. Ice cream samples were analyzed by their quality indices. Viscosity and texture of samples were studied by the rheological methods; the overrun was calculated. The microstructural properties, such as dispersion of ice crystals and air bubbles were investigated by the light microscopy. The sensorial properties were analyzed by 6 certified panelists. The reduction in viscosity by 9-74% with use of MPC, WPC and MPI and the increase by 96% with use of NWPI were noted. It was found that replacement of MSNF reduced the overrun by 36-67%. Study of microstructure showed that with use of protein isolates, mean size of ice crystals was reduced and with use of protein concentrates was increased. The increasing in mean size of air bubbles with use of NWPI was established. The studied textural parameters were increased with use MPC and MPI. The hardness and adhesiveness with use of NWPI were increased. The sensorial properties of samples with replacement of MSNF were not worse than with use of MSNF. It has been established that the replacement of MSNF with concentrates and isolates of milk and whey proteins can be an effective way to increasing the protein content in ice cream while maintaining or improving its sensory properties.

Effect of anhydrous milk fat fraction addition to butter on water loss reduction

Anhydrous milk fat (AMF) and AMF fractionated at 20, 25, and 30 °C were used in butter making to evaluate their effect on water loss (WL) and physical properties of butter. AMF and AMF fractions were incorporated into butter either in the cream before churning or in the working step. When AMF and AMF fractions were added, the cream method resulted in samples with decreased WL with high melting AMF fractions; the worked procedure butters had decreased WL with lower melting AMF fractions. The cream method WL had a significant positive correlation with water content and a significant negative correlation with hardness, crossover point, solid fat content (5–20 °C), enthalpy, and content of palmitic and oleic fatty acids (P < 0.05). The WL of worked method had a significant positive correlation with hardness, solid fat content at 5–20 °C, and myristic fatty acids (P < 0.05).

Development of technology for the production of cheese “Caciotta” for farms

Relevance. Russian farmers in recent years have begun to open small cheese factories. When meeting the requirements of production technology, farmers' cheeses are not inferior in quality to industrially produced cheeses. In this regard, the relevance of the development of technologies for the production of cheese in a farm is high. Research is aimed at developing a technology for the production of cheese “Caciotta” for farmers.Methods. The mass fraction of protein in milk was determined by the Kjeldahl method, the mass fraction of fat — by the acid method, the mass fraction of dry matter and dry skimmed milk residue — by the calculation method. The mass fractions of milk fat, protein, lactose, dry milk residue, dry skimmed milk residue, mineral salts, the amount of added water, density, freezing point, degree of homogenization, and temperature were determined by ultra-sonic method. Active acidity and titratable acidity, redox potential and temperature of milk were determined on a milk analyzer.Results. Under laboratory conditions, a technology for the production of semi-hard “Caciotta” cheese was developed, which is recommended for production on a farm.

Influence of the age of the first calving on some indicators of productive qualities of brown swiss cows in the conditions of the industrial complex

Presented the results of the research of the influence of different ages of the first insemination and the first calving of Brown Swiss cows on the realization of productive potential and reproductive qualities in a large industrial complex. Researches during 2019–2021 were conducted on the first-heifers of cows (n=242 cows) on the dairy industrial complex "Ekaterinoslavsky" of Dnipropetrovsk region. According to the age of the first calving, were formed five groups of first-heifers: group I (n=27) first calved at the age of 22.7 months, and fertilized – at the age of 13.4 months; group II (n=80) were first fertilized and calved at the age of 16.3 and 25.5 months, respectively; group III (n=56) – 18.9 and 28.1 months, respectively; IV group (n=38) – respectively 22,1 and 31.3 months; V group n=41 – respectively 26.5 and 35.8 months. The age of the first calving of experimental cows of all five groups differed at the level of P&lt;0.001.&#x0D; It was found that the level of average daily milk yield of Swiss first-heifers of different ages at the first calving has a significant intergroup difference. Cows of II and III groups are characterized by high and almost identical indicators, in which they are 30.0 and 30.3 kg, respectively. Slightly lower average daily milk yield is observed in Swiss animals of IV group, in which it does not exceed 29.0 kg, which was inferior to the first-heifers of II group by 3.45 %, and animals of III group – by 4.29 %. Relatively the lowest average daily milk yield is characterized by the first-heifers of I group, in which it does not exceed 28.8 kg, which practically was equal to the milk yield of IV group of Swiss animals and was less than cows of II and III group by 4.17 and 5.21 %, respectively. The highest level of average daily milk yield in first-heifers of I group, in which it did not fall below 32.2 kg. This figure exceeds the animals of II and III groups by 6.83 % (P&lt;0.05) and 5.90 % (P&lt;0.05), respectively. In comparison with the first-heifers of IV and V groups, animals of I group have higher milk yields per day by 9.94 % (P&lt;0.01) and 10.56 % (P&lt;0.01), respectively.&#x0D; It was found that in the researches, the mass fraction of milk fat of all groups of first-heifers was close and ranged from normal to 3.93 % to 4.07 %, and protein – an average of 3.31–3.53 %. The ratio of fat and protein averaged 1.16-1.20, which is normal.&#x0D; It was found that the highest rate of milk yield during 305 days of lactation have first-heifers of the first group, who calved at the age of 22.7 months and have a milk yield of 9810.4 kg. At the same time, the milk productivity cows of II group, which calved at the age of 25.5 months, averaged 9140.0 kg, which is 7.33 % less than I group cows (P&lt;0.05). In the first-heifers of III group, which calved for the first time at the age of 28.1 months, the level of milk productivity averages 9251.8 kg of milk, which is inferior to the first-heifers of I group by 6.04 % (P&lt;0.05). Swiss first-heifers of IV group, in which the first calving was at the age of 31.3 months, have a milk yield of 8832.2 kg of milk, which is 11.08 % less than the rate cows of I group (P&lt;0.01). Relatively the lowest level of milk productivity during 305 days of lactation is characterized by first-heifers of V group, in which the age of the first calving averaged 35.8 months. Only 8789.8 kg of milk was obtained from these animals, which is 12.32 % less than the first-heifers of I group (P&lt;0.01). The total production of milk fat and protein in the first-heifers of I group is the highest and averages 711.3 kg, which is 7.0 % more than animals of II group (P&lt;0.05).&#x0D; It is investigated that Swiss first-heifers of different ages of the first calving are characterized by satisfactory indicators of reproductive function, which are associated with a high level of milk productivity and do not depend on the age of the first calving. Compared to the biological norm in these cows, the service period is 1.76–2.24 times longer, the lactation period is 1.28–1.42 times longer, and the period between calving is 1,19–1,30 times. The adaptation index in all groups of first-heifers has a small negative value, which ranged from ˗5.89 to ˗8.23 units, which indicates satisfactory adaptive qualities in the conditions of intensive technology.

Detection of endocrine and metabolism disrupting xenobiotics in milk-derived fat samples by fluorescent protein-tagged nuclear receptors and live cell imaging

Nuclear receptors (NRs) are ligand-modulated transcription factors that regulate multiple physiological functions in our body. Many NRs in their unliganded state are localized in the cytoplasm. The ligand-inducible nuclear translocation of NRs provides a valuable tool for studying the NR-ligand interactions and their downstream effects. The translocation response of NRs can be studied irrespective of the nature of the interacting ligand (agonist, antagonist, or a small molecule modulator). These nuclear translocation studies offer an advantage over promoter-reporter-based transcription assays where transcription response is observed only with the activating hormones or agonistic ligands. Globally, milk serves as a major dietary source. However, suspected presence of endocrine/metabolism-disrupting chemicals like bisphenols, parabens, organochlorine pesticides, carbamates, non-steroidal anti-inflammatory drugs, chloramphenicol, brominated flame retardants, etc. has been reported. Considering that these chemicals may impart serious developmental and metabolism-related health concerns, it is essential to develop assays suitable for the detection of xenobiotics present at differing levels in milk. Since milk samples cannot be used directly on cultured cells or for microscopy, a combination of screening strategies has been developed herein based on the revelation that i) lipophilic NR ligands can be successfully retrieved in milk-fat; ii) milk-fat treatment of cells is compatible with live-cell imaging studies; and finally, iii) treatment of cells with xenobiotics-spiked and normal milk derived fat provides a visual and quantifiable response of NR translocation in living cells. Utilizing a milk-fat extraction method and Green Fluorescent Protein (GFP) tagged NRs expressed in cultured mammalian cells, followed by an assessment of NR response proved to be an effective approach for screening xenobiotics present in milk samples. Highlights Diverse endocrine and metabolism-disrupting chemicals are suspected to contaminate milk. Nuclear receptors serve as ‘xenosensors’ for assessing the presence of xenobiotics in milk. Nuclear import of steroid receptors with (ant)agonist can be examined in live cells. Lipophilic xenobiotics are extracted and observed enriched in milk-fat fraction. A comprehensive cell-based protocol aids in the detection of xenobiotics in milk.

Triacylglycerol composition and thermodynamic profiles of fractions from dry fractionation of anhydrous milk fat

This research provided a more in-depth look at the physiochemical properties of milk fat. The milk fat was fractionated between 30 and 15 °C into eight fractions with different melting points, the cooling step were successively 30, 25, 20 and 15 ℃. Physiochemical properties of different fractions, which include fatty acids, triacylglycerols, thermodynamics, and crystallization behavior, also were analyzed by using GC, UPLC-ESI MS, DSC and XRD. The results showed that the melting point of 30 S could reach 38.2 ℃ compared with the native milk fat (31 ℃) after fractionation. As the fractionation temperature decreased, the content of long-chain saturated fatty acids decreased. However, the content of short and medium-chain saturated fatty acids and unsaturated fatty acids showed an increasing trend, and the corresponding saturated triacylglycerols were also reduced. Besides, the high melting point fractions were mixed dominantly by β' crystal form at room temperature. The crystallization or melting temperature was relatively high, and the latent heat of phase change also was large. Therefore, these results demonstrated that the milk fat quality could be improved by dry fractionation and its application was expanded in production.

Distribution of selected trace elements in the major fractions of donkey milk

The aim of this study was to evaluate the concentrations of Zn, Cu, Mn, Se, Mo, Co, Li, B, Ti, Cr, Rb, Sr, Cd, and Pb in donkey milk and their distribution in major milk fractions (i.e., fat, casein, whey proteins, and aqueous phase). Individual milk samples were provided by 16 clinically healthy lactating donkeys. Subsequent centrifugation, ultracentrifugation, and ultrafiltration were carried out to remove fat, casein, and whey proteins to obtain skim milk, a supernatant whey fraction, and the aqueous phase of milk, respectively. Concentrations of the elements were measured in whole milk and fractions by inductively coupled plasma-mass spectrometry, and the concentrations associated with fat, casein, and whey proteins were then calculated. The effect of removal of fat, casein, and whey proteins was determined by repeated-measures ANOVA. The fat fraction of donkey milk carried a small (∼4.5% to 13.5%) but significant proportion of Mo, Co, Ti, Cr, and Sr. The casein fraction in donkey milk carried almost all milk Zn, a majority of Cu and Mn, and most of Mo, Ti, and Sr. Relevant proportions, between 20% and 36%, of Se, Co, and Cr were also associated with caseins. The majority of Se, Co, Li, B, Cr, and Rb, and relevant proportions of Mn, Mo, Ti, and Sr were found in soluble form (ultracentrifuged samples) and distributed between whey proteins and the aqueous phase of milk (ultrafiltered samples). Whey proteins in donkey milk carried the majority of milk Se and Co. All Li and B was present in the aqueous phase of milk, which also contained most Rb and Cr, and 17% to 42% of Mn, Se, Mo, Co, Ti, and Sr.

Similarity Index for the Fat Fraction between Breast Milk and Infant Formulas.

The similarity of the fat fraction in infant formulas rich in either bovine milk fat (MF) or vegetable oil (VO) to breast milk was evaluated by analyzing their lipid composition. Milk fat-rich formulas were highly similar (average similarity index 0.68) to breast milk compared to the VO-rich formulas (average similarity index 0.56). The highest difference in the indices was found in the contents of cholesterol (0.66 vs 0.28 in MF- and VO-rich formulas, respectively, on average) and polar lipids (0.84 vs 0.53), the positional distribution of fatty acids in the sn-2 position of triacylglycerols (0.53 vs 0.28), and fatty acid composition (0.72 vs 0.54). The VO-based formulas were superior in similarity in n – 6 PUFA. Thus, the addition of bovine MF fractions is an effective way to increase the similarity between the lipid composition of infant formulas and human milk.