STUDY OF FATTY ACID COMPOSITION OF MILK FOR CHEESE PRODUCTION

The article shows that the studied samples of raw milk in terms of composition (mass fraction of fat, protein, lactose and milk solids-not-fat) met the criteria of suitability for cheese, and its physic-chemical properties (titratable acidity, density, freezing point) were within acceptable limits. Moreover, rennet sample corresponded to the first and second classes. It was proved that the number of spores of lactating fermenting microorganisms met the requirements for milk for the production of any kind of cheese. It was established that the fatty acid composition of raw cow’s milk used to produce cheeses at various enterprises varied significantly. The data indicate the variability of the content of all groups of fatty acids — low molecular weight, saturated, monounsaturated and polyunsaturated. As a result of gas chromatography studies using the chromatographic complex «Chromos GX-1000» with a flame ionization detector and a CP 88 quartz capillary column — Sil 88 for FAME100 m × 0.25 mm × 0.2 µm, it was found that the largest absolute fluctuations were for saturated (± 7.03 % of the average value) and monounsaturated fatty acids (± 3.77 % of the average value). Absolute fluctuations in the group of low molecular weight fatty acids amounted to ± 2.62 %, and in the group of polyunsaturated — ± 1.02 % of the average value. The calculation of the relative deviation showed that the most varied groups were the ones of low molecular weight fatty acids (± 28.40 rel.%) and polyunsaturated fatty acids (± 25.11 rel.%). At the same time, a relatively high content of certain fatty acids: myristoleic, palmitic, palmitoleic and low levels of stearic and oleic fatty acids, was revealed in individual milk samples.The article shows that the studied samples of raw milk in terms of composition (mass fraction of fat, protein, lactose and milk solids-not-fat) met the criteria of suitability for cheese, and its physic-chemical properties (titratable acidity, density, freezing point) were within acceptable limits. Moreover, rennet sample corresponded to the first and second classes. It was proved that the number of spores of lactating fermenting microorganisms met the requirements for milk for the production of any kind of cheese. It was established that the fatty acid composition of raw cow’s milk used to produce cheeses at various enterprises varied significantly. The data indicate the variability of the content of all groups of fatty acids — low molecular weight, saturated, monounsaturated and polyunsaturated. As a result of gas chromatography studies using the chromatographic complex «Chromos GX-1000» with a flame ionization detector and a CP 88 quartz capillary column — Sil 88 for FAME100 m × 0.25 mm × 0.2 µm, it was found that the largest absolute fluctuations were for saturated (± 7.03 % of the average value) and monounsaturated fatty acids (± 3.77 % of the average value). Absolute fluctuations in the group of low molecular weight fatty acids amounted to ± 2.62 %, and in the group of polyunsaturated — ± 1.02 % of the average value. The calculation of the relative deviation showed that the most varied groups were the ones of low molecular weight fatty acids (± 28.40 rel.%) and polyunsaturated fatty acids (± 25.11 rel.%). At the same time, a relatively high content of certain fatty acids: myristoleic, palmitic, palmitoleic and low levels of stearic and oleic fatty acids, was revealed in individual milk samples

Budget Feasible Mechanisms for Experimental Design

In the classical experimental design setting, an experimenter E has access to a population of $n$ potential experiment subjects $i\in \{1,...,n\}$, each associated with a vector of features $x_i\in R^d$. Conducting an experiment with subject $i$ reveals an unknown value $y_i\in R$ to E. E typically assumes some hypothetical relationship between $x_i$'s and $y_i$'s, e.g., $y_i \approx \beta x_i$, and estimates $\beta$ from experiments, e.g., through linear regression. As a proxy for various practical constraints, E may select only a subset of subjects on which to conduct the experiment. We initiate the study of budgeted mechanisms for experimental design. In this setting, E has a budget $B$. Each subject $i$ declares an associated cost $c_i >0$ to be part of the experiment, and must be paid at least her cost. In particular, the Experimental Design Problem (EDP) is to find a set $S$ of subjects for the experiment that maximizes V(S) = \log\det(I_d+\sum_{i\in S}x_i\T{x_i}) under the constraint $\sum_{i\in S}c_i\leq B$; our objective function corresponds to the information gain in parameter $\beta$ that is learned through linear regression methods, and is related to the so-called $D$-optimality criterion. Further, the subjects are strategic and may lie about their costs. We present a deterministic, polynomial time, budget feasible mechanism scheme, that is approximately truthful and yields a constant factor approximation to EDP. In particular, for any small $\delta > 0$ and $\epsilon > 0$, we can construct a (12.98, $\epsilon$)-approximate mechanism that is $\delta$-truthful and runs in polynomial time in both $n$ and $\log\log\frac{B}{\epsilon\delta}$. We also establish that no truthful, budget-feasible algorithms is possible within a factor 2 approximation, and show how to generalize our approach to a wide class of learning problems, beyond linear regression

Research on the possibility of extending the shelf life of cheese raw material and heat-treated cheese by their freezing for further use in HoReCa

The article presents the results of a study of the regularities of changes in the functional properties and quality indicators of heat-treated cheeses made from frozen cheese raw material or frozen after thermomechanical processing for further use in HoReCa. The objects of the study were: Caliatta cheese — a semi-hard ripening cheese intended as the main raw material in the production of heat-treated cheese, as well as heat-treated «pizzacheese», subjected to freezing at temperatures of minus 14 ±2 °Cand minus 55 ±2 °Cand low-temperature storage at a temperature of minus 14 ±2 °Cfor 270 days, followed by defrosting at a temperature of 20 ±2 °C. To confirm the possibility of using the freezing technique in order to increase the shelf life of both the original cheese raw material and heat-treated cheese, their microbiological and physicochemical indicators were determined by standardized methods. Studies of structural and mechanical (rheological) properties were carried out on a Weissenberg rheogoniometer, recording changes in the elastic modulus (G’) and dynamic viscosity (h’). The length of the cheese thread, as one of the main functional properties of the «pizza-cheese», was assessed with a fork test after baking. Organoleptic characteristics were assessed by flavor, texture and appearance. Research results have shown that low-temperature storage of frozen cheese can be considered as a way to retard biological and physicochemical changes, which is a safe way to increase shelf life. Freezing cheese raw material increases the length of the cheese thread in proportion to the temperature and duration of the low-temperature storage. When obtaining heat-treated cheese from both unfrozen and frozen cheese raw material, a significant deterioration in the desired functional properties is observed. Thus, the receipt of heat-treated cheese from the original cheese raw material for further use in the production of pizza is justified only by economic feasibility. Freezing «pizza-cheese» at a temperature of minus 55 ±2 °C, made from unfrozen cheese raw material, ensures the preservation of functional properties and increases the shelf life up to 150 days

Thresholded Covering Algorithms for Robust and Max-Min Optimization

The general problem of robust optimization is this: one of several possible scenarios will appear tomorrow, but things are more expensive tomorrow than they are today. What should you anticipatorily buy today, so that the worst-case cost (summed over both days) is minimized? Feige et al. and Khandekar et al. considered the k-robust model where the possible outcomes tomorrow are given by all demand-subsets of size k, and gave algorithms for the set cover problem, and the Steiner tree and facility location problems in this model, respectively. In this paper, we give the following simple and intuitive template for k-robust problems: "having built some anticipatory solution, if there exists a single demand whose augmentation cost is larger than some threshold, augment the anticipatory solution to cover this demand as well, and repeat". In this paper we show that this template gives us improved approximation algorithms for k-robust Steiner tree and set cover, and the first approximation algorithms for k-robust Steiner forest, minimum-cut and multicut. All our approximation ratios (except for multicut) are almost best possible. As a by-product of our techniques, we also get algorithms for max-min problems of the form: "given a covering problem instance, which k of the elements are costliest to cover?".Comment: 24 page

On Budget-Feasible Mechanism Design for Symmetric Submodular Objectives

We study a class of procurement auctions with a budget constraint, where an auctioneer is interested in buying resources or services from a set of agents. Ideally, the auctioneer would like to select a subset of the resources so as to maximize his valuation function, without exceeding a given budget. As the resources are owned by strategic agents however, our overall goal is to design mechanisms that are truthful, budget-feasible, and obtain a good approximation to the optimal value. Budget-feasibility creates additional challenges, making several approaches inapplicable in this setting. Previous results on budget-feasible mechanisms have considered mostly monotone valuation functions. In this work, we mainly focus on symmetric submodular valuations, a prominent class of non-monotone submodular functions that includes cut functions. We begin first with a purely algorithmic result, obtaining a $\frac{2e}{e-1}$-approximation for maximizing symmetric submodular functions under a budget constraint. We view this as a standalone result of independent interest, as it is the best known factor achieved by a deterministic algorithm. We then proceed to propose truthful, budget feasible mechanisms (both deterministic and randomized), paying particular attention on the Budgeted Max Cut problem. Our results significantly improve the known approximation ratios for these objectives, while establishing polynomial running time for cases where only exponential mechanisms were known. At the heart of our approach lies an appropriate combination of local search algorithms with results for monotone submodular valuations, applied to the derived local optima.Comment: A conference version appears in WINE 201

Оценка микробиологических рисков в сливках как сырье для маслоделия

The article presents the research results of studying the influence of various groups of microorganisms — coliform bacteria, lactic acid microorganisms, yeast, and spore bacteria — on the quality and storage capacity of cream used as a raw material for buttermaking. The objects of study were the following: cream as a raw material before and after pasteurization, as well as pasteurized cream seeded with testing cultures of various types of spoilage microorganisms. The samples were stored at temperature conditions of 30 ± 1 °C, 10 ± 1 °C, and 4 ± 2 °C. To evaluate the quality and storage capacity of cream used as a raw material, its microbiological and physicochemical indicators were determined by standardized methods: bacterial number, titratable acidity, indicators of oxidative spoilage of the fat phase. Organoleptic characteristics were evaluated in terms of taste, consistency and appearance. Research results have shown that the greatest microbiological risks during storage of cream used as a raw material are associated with lactococci, coliform bacteria and yeast. Microbiological risks caused by seeding of cream with thermophilic streptococcus, spore bacteria of the genus Bacillus and spore anaerobic microorganisms of the genus Clostridium are less significant, which is associated with the lack of development and metabolism of these groups of microorganisms at storage temperatures of 10 ± 1 °C and 4 ± 2 °C. At the same time, the reason for the rejection of cream contaminated with these testing cultures, at a storage temperature of 4 ± 2 °C, is primarily a decrease in organoleptic indicators, and at a temperature of 10 ± 1 °C — an excess in bacterial number.В статье представлены результаты исследований по изучению влияния различных групп микроорганизмов: БГКП, молочнокислых микроорганизмов, дрожжей, споровых бактерий на качество и хранимоспособность сливок-сырья для маслоделия. В качестве объектов исследования служили: сливки-сырье до и после пастеризации, а также сливки пастеризованные, контаминированные тест-культурами различных видов микроорганизмов порчи. Хранение образцов осуществляли при температурных режимах 30 ± 1 °C, 10 ± 1 °C и 4 ± 2 °C. Для оценки качества и хранимоспособности сливок-сырья стандартизованными методами определяли их микробиологические и физико-химические показатели: бактериальную обсемененность, титруемую кислотность, показатели окислительной порчи жировой фазы. Органолептические показатели оценивали по вкусу, консистенции и внешнему виду. Результаты исследований показали, что наибольшие микробиологические риски при хранении сырых сливок связаны с лактококками, БГКП и дрожжами. Микробиологические риски, обусловленные обсеменением сливок термофильным стрептококком, споровыми бактериями рода Bacillus и споровыми анаэробными микроорганизмами рода Clostridium, менее значимы, что связано с отсутствием развития и метаболизма данных групп микроорганизмов при температурах хранения 10 ± 1 °C и 4 ± 2 °C. При этом основанием для забраковки сливок, контаминированных данными тест-культурами, при температуре хранения 4 ± 2 °C в первую очередь является снижение органолептических показателей, а при температуре 10 ± 1 °C — превышение по бактериальной обсемененности

Transforming growth factor β1 (TGF-β1) in patients with endocrine ophthalmopathy and Graves’ disease: A predictor of treatment efficiency

Current therapeutic approaches to the treatment of endocrine ophthalmopathy (EOP) are based on nonspecific immunosuppression with glucocorticosteroids (GCs) and radiation therapy of the eye orbits. However, some patients exhibit resistance to the treatment. In a previous study, we have detected high levels of soluble cytokine receptors: sTNFα-R1, sTNFα-R2, sIL-2R, and the TGF-β1 cytokine in euthyroid patients with long-lasting non-treated EOP and Graves’ disease (GD). TGF-β1 level was significantly higher in the patients with EOP compared to healthy individuals, and increased with prolonged EOP duration, thus suggesting activation of the factors regulating immune system which promote suppression of the autoimmune process. The aim of this work was to study the dynamics of TGF-β1 and cytokine receptors: sTNFα-R1, sTNFα-R2, sIL-2R in the course of immunosuppressive therapy with high doses of GCs, as possible predictors of treatment efficacy. The study included 49 patients (98 eye orbits) with GD of euthyroid state and subclinical thyrotoxicosis, and the persons with EOP in active phase, who had not previously treatment for EOP. Concentrations of TGF-β1 cytokine, sTNFα-RI and sTNFα-R2, sIL-2R, antibodies to the thyroid-stimulating hormone receptor (rTSH), free fractions of thyroxine (fT4) and triiodothyronine (fT3), TSH in blood serum were determined in blood serum. Ultrasound examination of the thyroid gland (ultrasound of the thyroid gland), multi-layer computed tomography (MSCT)/magnetic resonance imaging (MRI) of the orbits were also performed. The patients were administered immunosuppressive therapy with high doses of HCs (methylprednisolone) in the course of pulse therapy, at a standard dosage of 4500-8000 mg, taking into account the severity and activity of the EOP clinical manifestations. The examination was carried out 3, 6, 12 months after starting the treatment. 3 and 6 months after the GC administration, more than 30% of patients remained resistant to treatment. The levels of TGF-β1 did not change significantly in the patients with positive EOP dynamics. In the patients resistant to GC treatment, the level of TGF-β1 was significantly decreased compared with patients who showed positive clinical dynamics. The level of sNFR1 and sNFaR2 did not change significantly. There were no significant differences in the levels of antibodies to rTSH, thyroid hormones in the patients resistant to GC treatment and with positive dynamics.Immunosuppressive therapy with high-dose of methylprednisolone in pulse therapy regimen showed high efficacy and good tolerability, while some patients remain resistant to treatment. Lower levels of TGF-β1 cytokine at initial time and during the treatment allow usage of TGF-β1 levels as a biomarker of the activity of the process, treatment efficiency, and prognosis of the disease. Activation of TGF-β1, a fibroblast growth factor, may contribute to the development of fibrosis, strabismus, and diplopia

Исследование состава остаточной микрофлоры молока после пастеризации

The article presents the results of studies of the composition of the residual microflora of pasteurized milk, depending on the bacterial landscape and the initial contamination of raw milk. The thermal stability of test  cultures of microorganisms that significantly affect the  quality and  storage capacity of fermented dairy products has been  studied. To study  the  composition of the  residual microflora of milk after  pasteurization, sterile milk was infected with  test  cultures of microorganisms at doses  from  101 CFU/cm3 to 107 CFU/cm3. After infection, the  milk was pasteurized at temperatures of (72 ± 1) °C and  (80 ± 1) °C with  a holding time  of 10–20  seconds. The detection and  enumeration of microorganisms was carried out  by standardized microbiological methods. Microorganisms were identified by visual assessment of dominant colonies and cell morphology in micropreparations. The thermal stability of microorganisms important for dairy products, in particular cheeses, the source of which  is raw milk, has been  studied. It has been  established that of the  coccal  forms,  the  greatest risks are associated with  enterococci. Escherichia coli at  infection doses  above 106 CFU/cm3 partially retains viability both  at low-temperature and  at high-temperature pasteurization. Pasteurization temperatures do not have  a lethal effect on spore  bacilli, their number in pasteurized milk does not decrease, regardless of the  initial dose of infection. Low-temperature pasteurization activates the process of clostridial spore  germination. The ability to reactivate cells after  thermal shock was observed in Escherichia coli, Staphylococcus aureus, Pseudomonas, and  mold  fungi.  Thus,  the  residual microflora of milk  subjected to  low-temperature pasteurization is represented by enterococci, thermophilic streptococci, micrococci, staphylococci, asporogenous bacilli  and  spore bacteria. The above microorganisms constitute  the  residual microflora of pasteurized milk and are involved in the  maturation of cheeses, determining their quality and  safety,  [as well as] affecting the  storage capacity of the finished product.В статье представлены  результаты исследований состава остаточной микрофлоры  пастеризованного молока в зависимости от бактериального пейзажа и исходной обсемененности сырого  молока. Изучена термостабильность тест-культур микроорганизмов, значимо влияющих на качество и хранимоспособность ферментируемых  молочных продуктов. Для  исследования состава остаточной микрофлоры молока после  пастеризации стерильное молоко заражали тест-культурами микроорганизмов  в дозах от  101 КОЕ/см3 до 107 КОЕ/см3.  После  заражения молоко пастеризовали при  температурах (72 ± 1)  °C и  (80 ± 1) °C с выдержкой 10–20  секунд.  Выявление и  подсчет микроорганизмов  осуществляли стандартизованными микробиологическими методами. Идентификацию микроорганизмов проводили визуальной оценкой господствующих колоний и морфологии клеток в микропрепаратах. Исследована термостабильность микроорганизмов, значимых для  молочных продуктов, в частности сыров,  источником которых является сырое  молоко. Установлено, что из кокковых форм  наибольшие риски  связаны с энтерококками. Кишечная палочка при дозах  заражения выше 106 КОЕ/см3  частично сохраняет жизнеспособность как при низкотемпературной, так и при высокотемпературной пастеризации. На споровые палочки температуры пастеризации  не  оказывают летального действия, их  количество в пастеризованном молоке не снижается, независимо от исходной дозы  заражения. Низкотемпературная пастеризация активизирует процесс прорастания спор  клостридий. Способность к реактивации клеток после термошока наблюдалась у кишечной палочки, стафилококка, псевдомонад и плесневых грибов. Таким образом, остаточная микрофлора молока, подвергнутого низкотемпературной пастеризации, представлена  энтерококками, термофильным стрептококком, микрококками, стафилококками, аспорогенными палочками и  споровыми бактериями.  Вышеперечисленные микроорганизмы  составляют остаточную микрофлору пастеризованного молока и участвуют в процессах созревания сыров, определяя их качество и безопасность, влияют на хранимоспособность готового продукта

Возможность применения натуральных сыров для производства пиццы

The paper presents the results of studying sensory, physico-chemical, structural-mechanical (rheological) and biochemical indicators as well as functional properties of natural cheeses of various type groups for a possibility of using as a main raw material to produce pizza. Cheeses were produced in the research-and-development shop of the All-Russian Scientific Research Institute of Butter- and Cheesemaking (VNIIMS) and purchased in the retail chain. Sensory indicators (taste and odor, consistency, appearance) and functional properties (shreddability, meltability, blistering, free oil release, browning, stretchability) of cheeses from various groups were assessed by 100-point scale for assessing cheeses for pizza developed in VNIIMS. Shreddability was determined before baking by grinding a cheese sample chilled to a temperature of 4 ± 2 °C using a kitchen food grinder. Cheeses were baked at a temperature of 200 ± 5 °C for 12 min. Meltability was determined by changes in the cheese diameter after high-temperature treatment and stretchability by the “fork test”. It has been found that physico-chemical, structural-mechanical and biochemical indicators of cheeses used as a raw material affected sensory characteristics and functional properties of the final product after baking. The correlation between the fat content, protein mass fraction and active acidity of cheeses and functional properties such as meltability, free oil release, stretchability and shreddability was confirmed with statistical significance. The highest correlation was noted between shreddability, mass fraction of total protein and consistency (correlation coefficients were 0.74 and 0.76, respectively). However, none of the studied cheese types corresponded to the full extent to the targeted functional properties. To produce pizza, it is preferable to use cheeses with cheddaring and thermal-mechanical processing of cheese mass as well as unripened semihard cheeses with low temperature of the second heating that are molded from a layer, and semihard cheeses with high temperature of the second heating.В статье представлены результаты исследования органолептических, физико-химических, структурно-механических (реологических) и биохимических показателей, а также функциональных свойств натуральных сыров различных видовых групп для возможности использования в качестве основного сырья с целью производства пиццы. Сыры вырабатывались в экспериментальном цехе ВНИИМС и приобретались в торговой сети. Органолептические показатели (вкус и запах, консистенция, внешний вид) и функциональные свойства (натираемость, плавимость, образование блистеров, выделение свободного жира, сгораемость, растяжимость) сыров различных групп оценивали по 100- балльной шкале оценки сыров для пиццы, разработанной во ВНИИМС. Натираемость определяли до выпечки путем измельчения охлажденного до 4 ± 2 °C образца сыра на кухонном измельчителе пищевых продуктов. Выпечку сыров проводили при температуре 200 ± 5 °C в течение 12 мин. Плавимость определяли по изменению диаметра сыра после высокотемпературной обработки, а растяжимость — с помощью вилочного теста. Установлено, что физико-химические, структурно-механические и биохимические показатели сыров, используемых в качестве сырья, влияют на органолептические показатели и функциональные свойства конечного продукта после выпечки. Статистически достоверно подтверждена взаимосвязь между содержанием жира, массовой долей белка и активной кислотностью сыров и такими функциональными свойствами, как плавимость, выделение свободного жира, растяжимость и натираемость. Наибольшее взаимодействие отмечено между натираемостью, массовой долей общего белка и консистенцией (коэффициент корреляции равен 0,74 и 0,76 соответственно). Однако ни один из исследованных видов сыра в полной мере не соответствует искомым функциональным свойствам. Для производства пиццы наиболее предпочтительно использовать сыры с чеддеризацией и термомеханической обработкой сырной массы, а также незрелые полутвердые сыры с низкой температурой второго нагревания, формуемые из пласта, и полутвердые сыры с высокой температурой второго нагревания