Influence of milk-clotting enzymes of animal and microbial origin on the quality and shelf life of soft cheeses

A comparative test was carried out for milk-clotting enzymes (MCE) of animal origin (Naturen® Extra), microbial origin (Marzyme®) and MCE based on recombinant camel chymosin (Chy-max® M) in the production of soft cheese “Lyubitelskiy”. By the end of the shelf life of the cheeses (12 days at a temperature of 3 ± 1 °C), differences were noted in the degree of proteolysis (DP) and the value of the complex modulus G*, which were the following ones for cheeses produced with MCE of the brands: Naturen® — DP = 17.86 ± 0.24%; G* = 4164 ± 587 Pa; Marzyme® — DP = 17.98 ± 0.49%; G* = 4581±786 Pa; Chy-max® M — DP = 9.85 ± 0.63%; G* = 7949 ± 1157 Pa. Cheeses made with Chy-max® M MCE had a denser texture than cheeses made with MCE of Naturen or Marzyme, which did not differ significantly in consistency. In the studied cheeses, the severity of the bitter taste was proportional to the content of water-soluble peptides with a mass of 0.5–3 kDa. Cheeses with Marzyme® MCE had a more intense bitterness than cheeses with Naturen® MCE. There was no bitter taste in cheeses produced with MCE of Chy-max® M. It was concluded that in the production of soft cheeses, recombinant camel chymosin can be used to increase the shelf life, and MCE of microbial origin can be recommended to replace more expensive MCE of animal origin.

The Effect of Surfactants of Microbial Origin on Phytopathogenic Microorganisms

Biodegradable non-toxic surfactants of microbial origin are multifunctional preparations, which due to antimicrobial activity are promising for use in crop production to control phytopathogenic microorganisms. Studies on the prospects of using microbial surfactants to control the number of phytopathogenic microorganisms are conducted in three directions: laboratory studies of antimicrobial activity of surfactants in vitro, determination of the effect of surfactants on phytopathogens in vegetative experiments in the process of plants growing in a laboratory or greenhouse, post-harvest treatment of fruits and vegetables with solutions of microbial surfactants to extend their shelf life. The review presents literature data on antimicrobial activity of surfactants against phytopathogenic bacteria and fungi in vitro. Antimicrobial activity of surfactants is evaluated by three main parameters: minimum inhibitory concentration, zones of growth retardation of test cultures on agar media and inhibition of growth of test cultures on agar or liquid media. The vast majority of available publications relate to the antifungal activity of surfactant lipopeptides and rhamnolipids, while data on the effect of these microbial surfactants on phytopathogenic bacteria (representatives of the genera Ralstonia, Xanthomonas, Pseudomonas, Agrobacterium, Pectobacterium) are few. The researchers determined the antimicrobial activity of either total lipopeptides extracted with organic solvents from the culture broth supernatant, or individual lipopeptides (iturin, surfactin, fengycin, etc.) isolated from a complex of surfactants, or culture broth supernatant. Lipopeptides synthesized by members of the genus Bacillus exhibit antimicrobial activity on phytopathogenic fungi of the genera Alternaria, Verticillium, Aspergillus, Aureobasidium, Botrytis, Rhizoctonia, Fusarium, Penicillium, Phytophora, Sclerotinia, Curvularia, Colletotrichum, etc. in sufficiently high concentrations. Thus, the minimum inhibitory concentrations of lipopeptides against phytopathogenic fungi are orders of magnitude higher (in average 0.04–8.0 mg/mL, or 40–8000 μg/mL) than against phytopathogenic bacteria (3–75 μg/mL). However, the antifungal activity of lipopeptidecontaining supernatants is not inferior by the efficiency to the activity of lipopeptides isolated from them, and therefore, to control the number of phytopathogenic fungi in crop production, the use of lipopeptidecontaining supernatants is more appropriate. Rhamnolipids synthesized by bacteria of the genus Pseudomonas are more effective antimicrobial agents comparing to lipopeptides: the minimum inhibitory concentrations of rhamnolipids against phytopathogenic fungi are 4–276 μg/mL, which is an order of magnitude lower than lipopeptides. In contrast to the data on the antifungal activity of rhamnolipids against phytopathogens, there are only a few reports in the literature on the effect of these surfactants on phytopathogenic bacteria, whilst the minimal inhibitory concentrations are quite high (up to 5000 μg/mL). The advantage of rhamnolipids as antimicrobial agents compared to lipopeptides is the high level of synthesis on cheap and available in large quantities industrial waste. Currently in the literature there is little information about the effect of surface-active sophorolipids of microbial origin on phytopathogenic fungi, and all these works are mainly about the antifungal activity of sophorolipids. We note that in contrast to surfactant lipopeptides and rhamnolipids, the effective concentration of most sophorolipids, which provides the highest antimicrobial activity against phytopathogens, is higher and reaches 10,000 μg/mL.

The Effect of Aluminum Oxide Nanoparticles on the Activity of Amylases of the Enzyme Preparation of Microbial Origin

На основании анализа литературных данных показано, что изучение влияния наночастиц, в том числе оксида алюминия, на активность целевых ферментов микробных ферментных препаратов, применяемых в пивоваренном производстве, целесообразно. Приведены данные о влиянии наночастиц Al2O3 на процесс гидролиза крахмала в модельных средах под действием амилаз ферментного препарата «АПСубтилин П». Показано, что присутствие наночастиц в реакционной среде приводит к снижению амилолитической активности и, как следствие, снижению концентрации редуцирующих веществ в гидролизате на 12-15% (при содержании наночастиц 0,1 мг/см3) и на 34% (при содержании наночастиц 1,0 мг/см3) по сравнению с контролем. Установлено, что увеличение продолжительности ферментативного гидролиза с 60 до 120 мин приводит к ослаблению ингибирующего воздействия наночастиц Al2O3 на амилолитическую активность ферментного препарата. При этом присутствие наноразмерных объектов указанного типа не оказало негативного воздействия на результаты лабораторного затирания, проводимого по настойному способу с тремя паузами: основные показатели первого сусла опытных вариантов не уступали аналогичным характеристикам контрольного образца. На основании приведенных данных сделано заключение о нежелательности присутствия наночастиц Al2O3 в реакционных средах амилаз микробного происхождения в концентрациях, превышающих 0,1 мг/см3. The expediency of studying the effect of nanoparticles, in particular, aluminum oxide, on the activity of target enzymes of enzyme preparations used in brewing is substantiated based on the analysis of the literature data. Data on the effect of Al2O3 nanoparticles on the process of starch hydrolysis in model media under the action of amylases of the enzyme preparation «APSubtilin P» are presented. It has been shown that the presence of nanoparticles in the reaction medium leads to a decrease in amylolytic activity and, as a consequence, a decrease in the concentration of reducing substances in the hydrolyzate by 12-15% (at nanoparticle content of 0.1 mg/cm3) and by 34% (at nanoparticle content of 1, 0 mg/cm3) compared to the control. It was found that the increase in the duration of enzymatic hydrolysis from 60 to 120 min leads to a weakening of the inhibitory effect of Al2O3 nanoparticles on the amylolytic activity of the enzyme preparation. At the same time, the presence of nanoscale objects of this type did not have a negative impact on the results of laboratory mashing, carried out according to the infusion method with three pauses: the main indicators of the first wort of the experimental variants were not inferior to those of the control sample. Based on the data presented, it was concluded that the presence of Al2O3 nanoparticles in the reaction media of amylases of microbial origin in concentrations exceeding 0.1 mg/cm3 is undesirable.

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.

The Influence of Various Factors and Changes in the Concentration of the Substrate on the Action Enzymes of Microbial Origin

Использование ферментных препаратов микробного происхождения в промышленности имеет устойчивую тенденцию к увеличению, при этом 2/3 текущего объема составляют ферменты для пищевой промышленности, а их основная доля приходится на спиртовую отрасль. При этом потребность спиртовой отрасли России в комплексных ферментных препаратах составляет около 7 тыс. т, доля отечественных препаратов составляет менее 15%. Объектами исследований служили ферменты микробного происхождения, плесневые грибы, затор спиртового производства. Осахаривание проводили при температуре 57…58 °С, длительность брожения при этом составляла 62 ч. Установлено, что для достижения максимального действия фермента, при других постоянных условиях, требуется сравнительно большая концентрация субстрата. У большинства ферментов вне клетки она выше, чем концентрация данного вещества в организме, то есть фермент действует менее эффективно, чем в искусственно созданных условиях, где он насыщается субстратом. В зависимости от активности расход грибной культуры может колебаться в определенных пределах. Скорость и глубина гидролиза углеводов сырья определяются активностью глубинной культуры плесневого гриба. Таким образом, свойства ферментов определяются главным образом особыми свойствами белков. При этом в молекуле белка изменяется укладка пептидных цепей, что приводит к потере характерных свойств белка. Способность ферментов в благоприятных условиях пережить материнские клетки и проявлять свое действие вне клетки позволяет широко использовать биологические катализаторы в различных отраслях пищевой промышленности. The use of enzyme preparations of microbial origin in industry has a steady tendency to increase, with 2/3 of the current volume being enzymes for the food industry, and their main share is in the alcohol industry. At the same time, the need of the alcohol industry in Russia for complex enzyme preparations is about 7 thousand tons, the share of domestic preparations is less than 15%. The objects of research were enzymes of microbial origin, mold fungi, mash of alcohol production. Saccharification was carried out at a temperature of 57…58 °C, the duration of fermentation was 62 hours. It was found that to achieve the maximum effect of the enzyme, under other constant conditions, a relatively high concentration of the substrate is required. For most enzymes outside the cell, it is higher than the concentration of a given substance in the body, so the enzyme acts less efficiently than in artificially created conditions, where it is saturated with a substrate. Depending on the activity, the consumption of the mushroom culture can fluctuate within certain limits. The rate and depth of hydrolysis of raw carbohydrates are determined by the activity of the deep culture of the mold. Thus, the properties of enzymes are determined mainly by the special properties of proteins. In this case, the folding of peptide chains in the protein molecule changes, which leads to the loss of the characteristic properties of the protein. The ability of enzymes to survive mother cells under favorable conditions and to exert their action outside the cell makes it possible to widely use biological catalysts in various branches of the food industry.

Geochemistry of High-Molecular Weight Dimethylalkanes

—The homologous series of high-molecular weight dimethylalkanes (HMWDMAs) with either odd- or even-numbered carbon chains in the range from C19–20 to C30–31 have been identified in organic matter from recent and partially lithified deposits of Siberia and the Russian Platform by chromatography–mass spectrometry. The first homologous series is represented by even-numbered 3,4-HMWDMAs followed by the alternation of odd-numbered 3,5-HMWDMAs, even-numbered 3,6-HMWDMAs, and odd-numbered 3,7-HMWDMAs. The most abundant are 3,7-dimethylalkanes. The microbial origin of high-molecular weight dimethylalkanes is the most likely explanation for their presence in the fossil organic matter. The precursors of HMWDMAs might have been tetra- and diether lipids of archaea and bacteria. It is assumed that HMWDMAs and other immature hydrocarbons from great depths (SV-27 and SG-6 superdeep boreholes) result from the decomposition of asphaltenes, which occluded the related compounds inside their structure during the early stages of generation and carried them unchanged throughout the “oil window”.

Vaccines against the cold chain

Vaccines require continuous refrigeration to retain their efficacy as most vaccine components are derived from mammalian or microbial origin which are thermally unstable. Continuous refrigeration, known as the vaccine cold chain, comes at a cost that directly correlates to the standard of infrastructure that is available. A break in the cold chain caused by poor infrastructure can result in direct loss of functionality in these lifesaving medicines. Therefore, several approaches have been suggested to mitigate these losses. Not only will these benefit general healthcare via improved shelf-life but also enhanced resistance to thermal fluctuations and, in some cases, improved drug target localisation. In this minireview, we highlight trends in vaccine thermal stabilisation and look to the future for cold chain logistics.