Genetic factors affecting the composition and quality of cow’s milk

This chapter reviews the genetic factors affecting the composition and quality of cow's milk. It starts by discussing how different breeds of cattle can affect the composition of milk. The chapter then goes on to examine milk proteins, genetic variants and post-translational modifications. It then discusses milk coagulation and other functional properties, before highlighting the genetic influence of fatty acids on minor milk components. The chapter also discusses using mid-infrared spectroscopy for genetic parameter estimation, before concluding with a section on the possibilities for genetic improvement in relation to dairy milk.

Influence of different milk-coating enzymes on the process of producing soft cheeses

The effect of the type of milk clotting enzyme (MCE) on the duration of milk coagulation, parameters of the composition of whey and cheeses, and the output of cheeses in the production of soft cheese such as “Lyubitel'skiy” were investigated. Three brands of MCE of different origins were investigated: Marzyme® (MCE of microbial origin based on Rhizomucor miehei protease), Naturen® (calf rennet) and Chy-max® M (recombinant camel chymosin). It was established that MCEs had different ratios of milk clotting activity (MCA) to total proteolytic activity (PA). It was determined that the MCA/PA ratio, which characterizes the degree of specificity of the MCE action with regard to kappa-casein, in Chy-max M 1000 is ~7 times higher than that of Naturen and ~50 times higher than that of Marzyme. Such differences did not lead to a negative effect when using the Marzyme preparation in the production of soft cheeses. There were no statistically significant differences in the amount of dry matter loss of the curd into the whey, physicochemical parameters and output between the variants of cheeses made with the studied brands of MCE. Shorter duration of milk clotting (16.5 min) was observed with Marzyme than with MCE of Naturen (20.5 min) and Chy-max M (22.5 min). The results of the coagulation duration were explained by the stimulation of the activity of MCE of microbial origin, by the pH level of milk before coagulation (below pH 6.4). It was shown that modern MCEs of microbial origin could be recommended as a cost-effective replacement for more expensive rennet and recombinant chymosins in the production of soft and fresh cheeses.

Development of methodical approaches to assessing the formation of rennet-induced milk gels using the method of rotational viscometry

Формирование структуры сычужно-индуцированных молочных гелей, имеющее первостепенное значение в производстве целого ряда продуктов, наиболее объективно может быть охарактеризовано исключительно посредством инструментального измерения реологических параметров. В статье представлены результаты эксперимента по определению способности молочных систем с различной концентрацией сухих веществ к сычужному свертыванию с использованием ротационной вискозиметрии. Метод базируется на анализе изменений динамических показателей вязкости в процессе коагуляции молока, а также его УФ- и НФ-ретентатов с использованием вискозиметра Brookfield с последующей сравнительной графической оценкой кинетики гелеобразования и пиковой вязкости образующихся сгустков. Полученные данные подтвердили эффективность предлагаемых методических подходов для сравнительной оценки способности к сычужной коагуляции молока и его концентратов, полученных разными способами баромембранной обработки, и выявили перспективные направления исследований по изучению активности и дозировок молокосвертывающих препаратов, а также по выбору оптимальных температурно-временных режимов сычужной коагуляции молочных систем с прогнозированием их структурно-механических параметров. Rennet-induced milk gels are crucial for the production of a number of products. The formation of their structure can be objectively characterized only with the use of instrumental measurements of rheological parameters. The article presents the results of the experiment on determining the ability of milk systems with different dry substances concentration to rennet clot using rotational viscometry. This method is based on the analysis of changes in the dynamic viscosity indicators during the milk coagulation and its UV and NF retentates, followed by a comparative graphical assessment of the gelation kinetics and maximum clots viscosity. In our experiment, we used Brookfield viscometer. The presented data confirmed the effectiveness of the proposed methodological approaches for the comparative assessment of the ability to rennet coagulation of milk and its concentrates obtained by different methods of baromembrane treatment. A great prospect has been obtained in studies on the study of the activity and doses of milk-clotting enzymes and, the selection of the optimal temperature-time regimes of rennet clotting of milk systems with the prediction of their structural and mechanical parameters.

Novel Genes Associated with Dairy Traits in Sarda Sheep

The aim of the present research was to analyze the variability of 45 SNPs from different genes involved in metabolism and innate immunity to perform an association analysis with the milk yield, composition and milk coagulation traits. A population of 1112 Sarda breed sheep was sampled. Genotyping was generated by a TaqMan Open ArrayTM. Thirty out of the 45 SNPs were polymorphic, and 12 displayed a minor allele frequency higher than 0.05. An association analysis showed that the variability at genes PRKAG3 and CD14 was significantly associated with the daily milk yield. The variability at PRKAG3 was also associated with the protein and casein content, somatic cell score and bacterial score. The variation at the PRKAA2 gene was associated with the milk lactose concentration. The SNPs at CD14 were also associated with the traditional milk coagulation properties, while the SNPs at GHR and GHRHR were associated with kSR, a derived coagulation parameter related to the rate of syneresis. The information provided here is new and increases our knowledge of genotype–phenotype interactions in sheep. Our findings might be useful in appropriate breeding schemes to be set up for the Sarda sheep breed, but these should be confirmed by further studies, possibly performed on independent populations.

COMPARATIVE ASSESSMENT OF MILK PROTEIN COAGULANTS OF DIFFERENT ORIGIN

Потребность в увеличении количества и качества производимой молочной продукции стимулирует исследования, направленные на повышение эффективности переработки молочного сырья, что, в свою очередь, невозможно без изучения технологических свойств молока и функционально необходимых ингредиентов, применяемых в производстве различной молочной продукции. На основе научно-технической информации международных и российских баз данных, систематизированной в рамках изучаемой тематики, представлен обзор научных работ о коагулянтах белков молока различного происхождения, применяемых при кислотной, кислотно-сычужной и сычужной коагуляции. Установлено, что в российской и международной производственной практике востребованы коагулянты животного, микробного и рекомбинантного происхождения. Наибольшим спросом среди коагулянтов животного происхождения пользуется химозин, получаемый из желудков телят. Ферменты микробного и рекомбинантного происхождения отличаются более стабильным качеством и низкой стоимостью, но их производство, основанное на методах генной инженерии, вызывающих предубеждение у большинства потребителей, практически полностью сосредоточено за рубежом. При условии повышения лояльности потребителей ферменты рекомбинантного происхождения могут стать наиболее перспективными функциональными ингредиентами. Исследования потенциала различных протеолитических ферментов растительного происхождения выявили невысокий технологический эффект их применения. Рассмотренный материал позволяет прогнозировать перспективность научных исследований по выявлению механизмов коагуляции молока и новых эффективных и универсальных коагулянтов совокупно с селекционной практикой отбора животных, направленной на улучшение технологических свойств молочного сырья. The need to increase the quantity and quality of dairy products encourages research aimed at improving the efficiency of processing dairy raw materials, which, in turn, is impossible without studying the technological properties of milk and functionally necessary ingredients used in the production of various dairy products. On the basis of scientific and technical information from international and Russian data bases, systematized within the framework of the subject under study, a review of scientific works on milk protein coagulants of various origins used in acid, acid-rennet and rennet coagulation is presented. It is established that coagulants of animal, microbial and recombinant origin are in demand in the Russian and international production practice. The greatest demand among coagulants of animal origin is chymosin, obtained from the stomachs of calves. Microbial and recombinant enzymes are characterized by more stable quality and lower cost, but their production, based on genetic engineering methods that cause prejudice among most consumers, is almost entirely concentrated abroad. If consumer loyalty is increased, recombinant enzymes may become the most promising functional ingredients. Studies of the potential of various proteolytic enzymes of plant origin revealed a low technological effect of their use. The considered material allows us to predict the prospects of scientific research to identify the mechanisms of milk coagulation and new effective and universal coagulants together with the breeding practice of animal selection, aimed at improving the technological properties of dairy raw materials.

Physicochemical, Microbiological and Technological Properties of Red Deer (Cervus elaphus) Milk during Lactation

This study describes chemical, physical, microbiological and technological characteristics of red deer milk and the effect of lactation on these parameters in order to know their potential aptitude to elaborate dairy products. During 18 weeks, milk from five hinds was monitored for composition, bacteriology, somatic cell count (SCC), physical properties and rennet coagulation. Mean values (g/100 g) for fat, protein, lactose and dry matter were 10.4, 7.1, 4.3 and 24.2, respectively, and for urea, 265 mg/100 mL. Except for lactose, a significant increase in these components was observed (p < 0.01) as lactation progressed. The average values for bacteriology and SCC were 5.3 log cfu/mL and 4.7 log cells/mL, respectively. Regarding physical properties, conductivity (mean: 2.8 ms/cm), viscosity (3.1 Cp), coordinates L* (89.9) and a* (−3.1) and milk fat globule diameter (D4,3: 6.1 µm) increased along with lactation while density (1.038 g/mL) decreased (p < 0.01). The pH (6.7), acidity (22.9° Dornic), coordinate b* (8.4) and ethanol stability (66.6% v/v) were stable during the study period. The stage of lactation also has a significant impact on milk coagulation properties and mean curd yield was 3.29 g/10 mL. These results suggest that red deer milk could be a potential innovative source of milk for the dairy industry.