Autolytic Process Research Articles

Dysregulation of miR-381-3p and miR-23b-3p in skeletal muscle could be a possible estimator of early post-mortem interval in rats.

BackgroundThe post-mortem interval (PMI) is the time elapsed since the dead of an individual until the body is found, which is relevant for forensic purposes. The miRNAs regulate the expression of some genes; and due to their small size, they can better support degradation, which makes them suitable for forensic analysis. In the present work, we evaluated the gene expression of miR-381-3p, miR-23b-3p, and miR-144-3p in skeletal muscle in a murine model at the early PMI.MethodsWe designed a rat model to evaluate the early PMI under controlled conditions. This model consisted in 25 rats divided into five groups of rats, that correspond to the 0, 3, 6, 12 and 24 hours of PMI. The 0 h-PMI was considered as the control group. Muscle samples were taken from each rat to analyze the expression of miR-381-3p, miR-23b-3p, and miR-144-3p by quantitative RT-PCR. The gene expression of each miRNA was expressed as Fold Change (FC) and compared among groups. To find the targets of these miRNAs and the pathways where they participate, we performed an in-silico analysis. From the gene targets of miR-381-3p identified in the silico analysis, the EPC1 gene was selected for gene expression analysis by quantitative RT-PCR in these samples. Also, to evaluate if miR-381-3p could predict the early PMI, a mixed effects model was calculated using its gene expression.ResultsAn upregulation of miR-381-3p was found at 24 h-PMI compared with the control group of 0 h-PMI and (FC = 1.02 vs. FC = 1.96; p = 0.0079). This was the opposite for miR-23b-3p, which had a down-regulation at 24 h-PMI compared to 0 h-PMI (FC = 1.22 vs. FC = 0.13; p = 0.0079). Moreover, the gene expression of miR-381-3p increased throughout the first 24 h of PMI, contrary to miR-23b-3p. The targets of these two miRNAs, participate in biological pathways related to hypoxia, apoptosis, and RNA metabolism. The gene expression of EPC1 was found downregulated at 3 and 12 h of PMI, whereas it remained unchanged at 6 h and 24 h of PMI. Using a multivariate analysis, it was possible to predict the FC of miR-381-3p of all but 6 h-PMI analyzed PMIs.DiscussionThe present results suggest that miR-23b-3p and miR-381-3p participate at the early PMI, probably regulating the expression of some genes related to the autolysis process as EPC1 gene. Although the miR-381-3p gene expression is a potential estimator of PMI, further studies will be required to obtain better estimates.

MORPHOLOGICAL FEATURES OF THE UTERUS IN WOMEN AT DIFFERENT TIME INTERVALS OF THE POSTMORTEM PERIOD AS DIAGNOSTIC CRITERIA FOR ESTABLISHING THE POSTMORTEM INTERVAL

The aim is to identify the morphological features of the uterus layers in women at different time intervals of the postmortem period as diagnostic criteria for establishing the postmortem interval. Materials and methods: In the study we used surgical and autopsy material - uterine tissue fragments. All materials were divided into two groups. The 1st group (G 1) included surgical material from women (n=6) who underwent removal of the uterus, or uterus with the appendages due to leiomyoma, uterine prolapse. The 2nd group (G 2) included autopsy material from 42 women with known causes of death and postmortem period (from 24 to 48 hours - 6 cases, from 49 to 72 hours - 7 cases, from 73 to 96 hours - 8 cases, from 97 to 120 hours - 6 cases, from 121 to 144 hours - 8 cases, more than 144 hours - 7 cases). Histological and immunohistochemical study methods were used. Results: A comprehensive morphological study of the women uterus revealed a time-dependent increase of postmortem changes in this organ linked with the increase of postmortem period. In cases of postmortem period duration up to 144 hours, the structural elements of the uterine layers were identified. In cases where the duration of the postmortem period was more than 145 hours, microscopically the uterus was represented by eosinophilic fibrous or dusty masses, the histogenesis of which could not be determined. The processes of autolysis occurred more intensely and faster in the mucous membrane of the uterus, in comparison with the muscular and serous membranes, and in the vessels - in their inner membrane, in comparison with the middle and outer membranes. Autolytic changes in the muscular membrane of the uterus and vascular walls occurred more intensely in muscle fibers compared to connective tissue fibers. Conclusions: The histological and immunohistochemical features of the women uterus at different postmortem periods have a certain forensic medical significance and can be used for establishing the postmortem interval.

Advances in yeast autolysis technology - a faster and safer new bioprocess

Abstract The yeast autolysis process - an endogenous and irreversible lytic event, which occurs in cells caused by the action of intracellular enzymes, proteases and carbohydrases - is a well-known and an economic process, however, there is a constant risk of serious microbial contamination since there are many nutrients in the broth and this process is slow, favoring the growing of pathogens. The present work comes up with an attempt to accelerate the autolysis of Saccharomyces cerevisiae with focus on the high yield of yeast extract production through a fast, economic and simple technology. The proposed strategy is based on decreasing the pH of the yeast suspension at the beginning of autolysis through an acid shock to activate the cell autolytic system under stressful conditions of temperature and pH. The influence of cell concentration, temperature, time and acid shock at the beginning of the autolysis on yeast extract yields were studied. The best yields of proteins and total solids were observed for autolysis treated with acid shock (H2SO4 10 µL/g of dried yeast and final pH 4.4) at 60 °C (36, 84% of protein and 48, 47% of total solids extracted) and gradual increase of temperature 45 to 60 °C (41.20% of protein and 58.48% of total solids extracted). The shock could increase the speed of the process since the control reached about 30% of extract at 60 °C and the same experiment, however, with acid shock reached more than 43% in 12 h. When considering time in an industrial scale, it could be noted that the time was very important for the productivity as well as avoiding risk of pathogen contamination in autolysis. These results were very relevant for industrial purposes in the production of yeast extract, autolyzed yeast and glucan and mannan.

Protocol to classify the stages of carcass decomposition and estimate the time of death in small-size raptors

One of the most common wildlife crimes involving birds worldwide is malicious poisoning. Post-mortem examination and toxicological analysis are essential for a proper diagnosis of the cause of the poisoning. However, investigators often require an estimate of the time of death, which is best determined by identifying the stage of carcass decomposition. The aim of this article is to propose a scoring method to classify the stages of carcass decomposition and thus provide an estimate of the time of death in small-size raptors. This protocol can be used by practitioners, forensic veterinarians, researchers, authorities and personnel collecting carcasses in order to standardize methods and minimize subjectivity. For this purpose, 12 carcasses of Common kestrel (Falco tinnunculus) were exposed to external weather conditions (in the period 4–19 July 2019) in Murcia, Southeastern Spain. The ambient temperature and relative humidity, body core temperatures and carcass weights were measured at intervals over the study period. Necropsies were performed (2 birds at each interval) at 1–2 h, 24 h, 72 h, 96 h, 7 days and 15 days after death. The necropsy of a previously frozen bird was performed to act as a comparison with non-frozen fresh individuals. Six stages of the post-mortem autolytic process were selected: fresh carcass, moderate decomposition, advanced decomposition, very advanced decomposition, initial skeletal reduction and complete skeletal reduction. To classify the carcasses according to these categories, a scoring method is proposed considering 5 parameters: state of the eyeballs, tongue/oral cavity, pectoral muscle, internal organs and other features. Several parameters affecting the process of the decomposition are discussed.

An effect of high altitude on yak meat autolysis

The autolysis has a great influence on the meat quality. Currently, the autolysis process is defined in lamb, beef and pork. The autolysis influence on the quality of yak meat was researched only by the scientists of Ulan-Ude University. However, the influence of high- mountains on the autolysis of yak meat was not found in the literature. In this connection, the issue of autolysis process in yak meat in high-mountain conditions causes a great interest. The high-mountain conditions have the effect on the autolysis process of yak meat. The initial pH of the meat rises with the increase of altitude above the sea level. The autolysis process of yak meat from Chui region coincides with beef, while in high-mountain regions it has its own characteristics.

Influence of heat treatment regimens on the characteristics of poultry products using targeted fermentation application

The article reveals some aspects of the influence of the duration of heat treatment and different types of functional mixtures on the functional and technological characteristics of broiler meat products at low temperature processing under the condition of target fermentation. Broiler meat has several advantages for use as a raw material in the production of Sous-Vide products. These advantages include high moisture content, high organoleptic characteristics, and relatively low cost of this raw material. However, there are a few disadvantages that complicate the processing of broiler chicken meat by Sous Vide technology. These include the high amount of moisture released during production and the low moisture-binding capacity of some batches of raw materials (often associated with excessive moisture or disruption of autolytic processes in broiler chickens). To achieve the desired consistency and high organoleptic characteristics, enzyme preparations are widely used in the meat processing industry. To eliminate these shortcomings, it is proposed to use functional mixtures, which are introduced into the raw meat by injection, as well as the use of targeted fermentation. During the experiment, 2 formulations of broiler chicken meat products were developed, which in turn were treated in two heat treatment regimens and treated with the enzyme transglutaminase. In the first batch of samples, an injection of 15% solution of a functional mixture based on citrates was used, while in the second batch - a similar level of injection of a mixture based on phosphates. Heat treatment was performed after pre-application in bags and vacuum at 62 ℃ for 120 and 140 min for different groups of samples. In all samples, the yield of the finished product, the relative weight of the separated moisture (broth) in the package, the values of pH, water holding and moisture-retaining capacities, as well as the total moisture content in the finished product were determined. According to the obtained results, the optimal is samples with the use of phosphates, and 120 minutes the duration treatment is 120 minutes.

Optimization of the poultry meat heat treatment process with phosphate mixture application

This article highlights the impact of different heat treatment modes on Sous Vide of poultry meat products (fillets and thighs of broiler chickens) on the main functional and technological characteristics of the finished product. All prototypes were obtained from commercial networks and showed signs of impaired PSE autolytic processes with a product pH of 5.6-5.8. Samples were injected with phosphate solution to increase pH and to increase functional and technological characteristics. The formulations of all the samples included 85% of the main raw meat (fillets and thighs of broiler chickens) and 15% solution of a functional mixture based on phosphate and fiber. A complete two-factor experiment was constructed to determine the optimal modes of product heat treatment. The factors chosen were the time and temperature of the heat treatment, which varied, respectively, along the upper limit of values at 68 ° C and 120 min and 62 ° C for 100 min at the lower limit of values. The introduction of the functional mixture was carried out by the same method at a minimum pressure of 0.15 Bar, after which the raw material was placed in vacuum bags, created a vacuum and kept for 90 minutes to initiate the processes of binding of moisture by the ingredients of the mixture. The solution temperature of the functional mixture before injection is 4 ° C, and the temperature of the raw material in the muscle thickness is 6 ° C. Water holding capacity, yield and pH of the finished product, the amount and pH of the broth separated during the heat treatment, and the plasticity of the finished product were selected as experimental parameters. According to the obtained results, the treatment temperature of 62 ºС is considered optimal with treatment duration of 120 min. These treatment regimes allow achieving the values of water holding capacity at 80-82% for broiler chicken fillets and 79-80 ºC for the thigh. The difference between the level of indicators for the thigh and the broiler chicken fillet was within 5% for all characteristics except plasticity, which was significantly greater for the finished thigh of the broiler chickens.

The effect of moderate pulsed electric fields on autolysis of Saccharomyces cerevisiae and the amino acid content in autolysates

SummaryThe effect of moderate pulsed electric fields (MPEF) strength on autolysis of Saccharomyces cerevisiae was evaluated in this study. After exposure to MPEF with intensity of 7 kV cm−1 for 4 ms, the integrity of the cell wall was obviously destroyed and the inactivation of S. cerevisiae reached 99.43%. During the subsequent 42‐h autolysis process, the release of free α‐amino nitrogen of MPEF‐treated cells, as well as extracellular protease activity, was significantly (P < 0.05) higher than that of untreated cells. Moreover, exposure to 7 kV cm−1 led to an increase of the total amino acid of 149.36%. In particular, the content of aspartic acid and glutamic acid which are important umami flavour precursors increased by 232.55% and 209.40%, respectively. These results indicate that MPEF will be an effective method to accelerate autolysis of S. cerevisiae for obtaining high‐quality yeast extract as flavour enhancers and nutrition supplements.

Transcriptomic analysis reveals MAPK signaling pathways affect the autolysis in baker's yeast.

Yeast autolysis refers to the process in which cells degrade and release intracellular contents under specific conditions by endogenous enzymes such as proteases, nucleases and lipid enzymes. Protein-rich baker's yeast is widely used to produce yeast extract in food industry, however, the molecular mechanism related to baker's yeast autolysis is still unclear. In this study, RNA-seq technology and biochemical analysis were performed to analyze the autolysis processes in baker's yeast. The differentially expressed genes (DEGs), 27 autolysis-related euKaryotic Ortholog Groups (KOG) and three types of autolysis-induced Gene Ontology (GO) were identified and analyzed in detail. A total of 143 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways under autolysis were also assigned. Interestingly, the DEGs were significantly enriched in the mitogen-activated protein kinase (MAPK) signaling pathways and metabolic pathways, and key genes MID2, MTL1, SLT2, PTP2, HKR1 and GPD1 may play important roles in autolysis. Further quantitative PCR was performed to verify the expression pattern in baker's yeast autolysis. Together, all these results indicated that MAPK pathways might play an essential role during autolysis process through inhibiting the metabolism and disrupting cell wall in baker's yeast. This result may provide important clues for the in-depth interpretation of the yeast autolysis mechanism.

Dependence of physicochemical properties and chemical composition of pig meat on the genotype and pre-slaughter live weight of pigs

The article presents the results of analysis of the main chemical composition values (total moisture, dry matter, intramuscular fat, protein and ash contents) and physical properties (pH1, pH16, pH24, water-holding capacity) of the longest back muscle for different genotypes of pigs of different genetic combinations under two weight conditions (100 and 120 kg).It was found that the acidity levels and water-holding capacity of meat of animals from all study groups were within the limits established in the processing industry and fitted into the European category NOR (normal). Autolytic processes in the muscle tissues of high-intensity foreign genotypes are more intensive than those of native genotypes. An increase in the pre-slaughter liveweight from 100 to 120 kg had no effect on the water-holding capacity of meat, but its active acidity (pH) tended to decrease as the animals gained weight. It was found that the meat of pigs from intensive commercial genotypes of foreign selection had higher protein levels and lower fat and ash contents compared with meat of native pig breeds. With an increase in the pre-slaughter weight from 100 to 120 kg the intramuscular fat content in the meat of animals of all genotypes under study increased due to reduction in the protein and moisture levels. It was further found that the use of these genetic combinations led to a decrease in the water-holding capacity and active acidity levels. The meat of pigs produced by combination of native genotypes (UVB-1×UVB-2)×UVB-3 has the best physicochemical properties. Animals produced by mating a combination of sows (Yi ×Li ) and (Li ×Yi ) and boars of synthetic MaxGrow and MaxTer terminal lines had the highest protein levels in their meat both with the 100 kg and 120 kg pre-slaughter weight. Key words: meat, musculus longissimus dorsi, quality, physicochemical composition, terminal boars, active acidity, water-holding ability.

Biochemical Factors Affecting the Quality of Products and the Technology of Processing Deep-Sea Fish, the Giant Grenadier Albatrossia pectoralis

The composition of muscle tissues of a deep-sea species, the giant grenadier (Albatrossia pectoralis), and a mesopelagic species, the Alaska pollock (Theragra chalcogramma), are compared. Grenadier is proved to have a higher moisture content (91.7%) and lower protein (7.4%) and lipid (0.3%) contents. The factors responsible for the softening and moisture separation during processing of grenadier are identified. Contents of some fractions of non-protein nitrogenous components, including trimethylamine oxide (TMAO) and free amino acids, are clarified. The proportion of the main myofibrillar proteins myosin and actin, which is considered as an indicator of efficiency of structure formation in fish muscle tissue during processing, is almost 20% lower in giant grenadier than in pollock. The effects of endogenous protease, Ca2+-ATPase and transglutaminase on the processes of autolysis, denaturation, and possibility of myofibrillar proteins cross-linking were also studied. The proposed technology of getting a nutritionally balanced, gel-like, ready-to-use foodstuff from grenadier fillet includes its enrichment with pollock muscle tissue and supplementing with a binary structure-forming agent containing collagen and chitosan. Nutritional value of the products is assessed by the method of biological assay and by determining the denaturation changes of myofibrillar proteins. The modes of fine mincing and thermal processing, as well as the shelf-life of the finished product are justified. The developed technology of producing a ready-to-eat food from giant grenadier will allow a more efficient use of this underutilized resource.

Effect of high pressure homogenization on the production of yeast extract via autolysis and beta-glucan recovery

The aim of this study was to assess the application of high pressure homogenization (HPH) as a pretreatment prior to the process of autolysis of Saccharomyces cerevisiae cells in order to enhance both the production of yeast extract and the valorization of the solid residue of autolysis for β-glucan extraction. Autolysis of HPH treated (200–600 bar, 1–3 passes) and untreated samples, carried out at 52 °C and pH = 5.5, was mathematically modelled based on protein, amino acid and total solids release. HPH treatment accelerated yeast autolysis at all conditions studied and resulted in higher protein, amino acid and total solids yield. A combination of HPH treatment and shorter autolysis times achieved high extract yields of low turbidity. The β-glucan content of the solid autolysis residue increased with increasing treatment intensity and autolysis time with a simultaneous decrease in protein content due to the mechanical disruption of the cells. Industrial relevanceThe use of HPH as a pretreatment of yeast suspensions allows for the acceleration of yeast extract production by autolysis, reducing the very long autolysis times otherwise required. At the same time, the solid residue obtained after autolysis has a higher β-glucan content for HPH treated samples, allowing for more efficient valorization of this rich in valuable glucan by-product. In our work we have demonstrated that with one pretreatment step, both aspects of the autolytic process can be significantly enhanced.

Tanatological assessment of long-brain structures in death from hemorrhagic shock at different post-mortal periods

Authors determined the morphological and morphometric characteristics of nerve and vascular structures in death from blood loss complicated by hemorrhagic shock. The medulla oblongata of 12 corpses of persons who died from stab wounds of blood vessels and internal organs with sharp instruments at different times of the postmortem period was studied. Studies were carried out at stages of 6-8 hours, 12-14 hours, 18-20 hours, 24 hours or more of the postmortem period. It was found that as the interval after death from hemorrhagic shock increases, there is an increase in destructive changes, both neurons and intracerebral vessels in the medulla oblongata. Autolytic processes to a greater extent capture the intracerebral vessels comparing with neurons, which is more pronounced in the later stages of the study. The sizes of perineural and perivascular spaces in the dynamics of the postmortem period increase synchronously, which reflects the permanence of manifestations of tanatogenesis in different periods after death from hemorrhagic shock.

Sustainable and Effective Chitosan Production by Dimorphic Fungus Mucor rouxii via Replacing Yeast Extract with Fungal Extract

The effects of switching morphology and replacing supplementary nutrients with fungal extract (5 and 10g/L) on the production of major metabolites and chitosan by Mucor rouxii were investigated. This approach was supposed to promote sustainability of the fermentation process and improve its economic feasibility. Different fungal morphologies, i.e., purely filamentous (PF), purely yeast-like (PY), mostly filamentous (MF), and mostly yeast-like (MY), were evaluated. The highest ethanol yields were obtained from the media supplemented with 10g/L fungal extract for all morphologies, while adding nutrient salts did not make any improvements in these yields, except a slight decrease in the fermentation time. Except for PF morphology, the replacement of yeast extract favored the biomass production yields. Moreover, the alkali insoluble material (AIM) yields were higher as a result of the replacement for most cases. Furthermore, the replacement resulted in increased glucosamine and decreased N-acetyl-glucosamine content of AIM for almost all the morphologies. AIM yields of at least 0.25g/g-glucose and maximum chitin/chitosan yield of 0.78g/g-AIM were obtained from the solids remaining after autolysis process, which were higher than that obtained from the raw biomass. The maximum yield of 0.135g/g-AIM purified chitosan with intact molecular weight was obtained from the biomass with PF morphology supplemented with 10g/L fungal extract plus nutrients.

Detection of protein aggregation markers in raw meat and finished products

The effect of animal and plant proteases as well as starters, or starter cultures, on protein aggregates for- mation in raw pork and beef as well as meat products was studied. The proteomic analysis of raw meat revealed that animal proteases – pepsin and trypsin – caused the aggregation of isoform 2 of protein 1 containing 4.5 LIM domains. Vacuum packaged meat showed the same results during storage, while unpacking led to the acceleration of the aggregation process due to autolysis. In addition, mixed aggregated fragments, such as muscle creatine phos- phokinase and glutathione-S-transferase, actin and perilipin, and type II keratin appeared in those samples. Starters with Pediococcus pentosaceus 31 from the Russian National Collection of Industrial Microorganisms (VKPM-8901) caused myoglobin and troponin I aggregation, while the formation of soy proteins aggregates (glycinin G1 and glyci- nin A3B4) was detected in meat products as a result of the autolysis process and the use of cholesterol-lowering star- ters. All in all, proteases which cause protein aggregation may be less effective for raw meat tenderization, whereas the proteins identified may be used as quality biomarkers.

Determination of nucleotide and enzyme degradation in haddock (Melanogrammus aeglefinus) and herring (Clupea harengus) after high pressure processing.

BackgroundThe degradation of nucleotides and their enzymes had been widely used to evaluate fish freshness. Immediately after fish death, adenosine triphosphate (ATP) degrades into inosine-5-monophosphate (IMP) via adenosine-5-diphosphate (ADP) and adenosine-5-monophosphate (AMP). IMP degradation continues to produce inosine (ino) and hypoxanthine (Hx) and further deteriorates the fish by producing xanthine and uric acid. The dephosphorylation of IMP to Ino is carried out by the enzyme 5′-nucleotidase (5′-NT), whereas the degradation of Ino to Hx is carried out by the enzyme nucleoside phosphorylase (NP). This study assesses the application of high pressure processing (HPP) in two species of fishes; haddock (Melanogrammus aeglefinus) and herring (Clupea harengus) as a means to extend the shelf-life by slowing down the rate of nucleotides degradation.MethodsHaddock (Melanogrammus aeglefinus) and herring (Clupea harengus) fillets were subjected to HPP at 200, 250 and 300 MPa for 1 and 3 min before being stored for 14 days. In addition, 5′-NT and NP enzyme activities were determined on both fish species that were subjected to 100–600 MPa for 1 and 3 min.ResultsAdenosine triphosphate, ADP and AMP in both haddock and herring were lower at higher pressure levels. Inosine (Ino) increased (p < 0.05) after treatment at higher pressures in both species. Hx in herring decreased significantly (p < 0.05) at higher pressures but not in haddock. K values are the ratio of Ino and Hx to all nucleotides. K values in haddock were not significantly (p > 0.05) affected by the pressure treatment. H values are ratio of Hx to the sum of IMP, Ino and Hx. H values in haddock were significantly decreased (p < 0.05) with increasing pressure level. F values are ratio of IMP to the sum of IMP, Ino and Hx. F values showed no significant effects (p > 0.05) after pressure treatment. Furthermore, K values in control herring were significantly higher (p < 0.05) than those of the pressure-treated samples. H values in herring decreased significantly (p < 0.05) with increasing pressure level. F values in herring showed no significant effects (p > 0.05) after pressure treatment. Pressure treatment brought a significant decrease (p < 0.05) in protein content in both haddock and herring. 5′-NT activity was 20–35 fold higher compared to NP activity in haddock and 15–44 fold higher than NP activity in herring. 5′-NT and NP activities decreased significantly with increasing pressure level in both species.DiscussionHigh pressure processing effectively slows down the conversion of Ino to Hx, delaying the undesirable flavour that develops in spoiling fish. The autolytic conversion of IMP to Ino by endogenous 5′-NT predominates in the earliest stages of storage is an autolytic process. However, both bacterial and endogenous NP enzymes are probably responsible for the gradual accumulation of Hx in fish. K values are recommended as a useful measurement of fish freshness.

Evaluation of rabbit meat properties as raw material for functional products manufacturing

The research results of the mass yield and composition of the anatomical areas of rabbits carcass, the mechanisms of autolysis of rabbit meat and histomorphological changes during the course of autolysis were presented in the work. The degree of protein digestibility of rabbit muscle tissue was determined. The object of research was the California rabbit carcass. It was established that the process of meat maturing would be completed in 8 hours. Matured meat is characterized by higher nutritional value and quality. The developing in the rabbit carcass processes affect the functional and technological properties of meat during the rigor mortis resolution and at the beginning of the maturing stage. Functional and technological properties are: 53.7% - water-binding capacity and 50.6% - water-holding capacity. 24 hours later after slaughter, the functional and technological properties as a whole increased to 64.1 and 61.7, respectively, which corresponds to 85% of fresh-killed meat. Such indicators of functional and technological properties are due to the high content of high-quality complete proteins. The high digestibility of the protein components of rabbits muscle tissue was observed. The autolysis stages were illustrated by the microstructural and qualitative characteristics of rabbit meat. The deep character of autolytic processes in the longest back muscle 12 hours after rabbit slaughter, which resulted in the formation of physico-chemical, biochemical, organoleptic properties of meat, ensuring products high quality was identified. Less intensive processes took place in the muscle tissue of piriformis muscle, as well as the pre-blade muscle, which was explained by the structure peculiarities of these parts of the muscular system. The research results indicate the prospects of rabbit meat using in functional products manufacturing. The technologies developed allow to take into account preferences and income level of consumers.

Optimization of yeast autolysis under solid-state fermentation conditions

Yeast autolysis under solid-state fermentation can effectively promote the release of various active substances, thereby improving the quality of yeast products. The optimal process for yeast autolysis under solid-state fermentation was obtained by optimizing the autolysis temperature, autolysis time and the zinc ion concentration. We analyzed the indexes of free amino acid, soluble protein and α-amino nitrogen in the fermentation material, as well as A₂₆₀/A₂₈₀ ratio to determine yeast autolysis process conditions in the solid-state fermentation. On the basis of the obtained data, L₉ (3³) orthogonal test was designed to optimize the solid-state fermentation parameters for yeast autolysis: temperature at 40, 50 and 55 °C; time 12, 18 and 24 h; zinc ion concentration 2, 4 and 8 mg/kg. The optimum process conditions for yeast autolysis were: autolysis temperature 55 °C, time 18 h, zinc ion concentration 2 mg/kg, and soluble protein content reached 9.31 mg/g, free amino acid 14.36 mg/g, α-amino nitrogen 10.16 μg/g and A₂₆₀/A₂₈₀ 1.73. After optimization of the process, the soluble protein, free amino acid and α-amino nitrogen contents of the yeast autolysis production can be significantly increased, thereby obviously improving the quality of the composite culture.

Iron-mediated deep-time preservation of osteocytes in a Middle Triassic reptile bone

ABSTRACT Fossil bone cells (osteocytes) are known mainly from the shape-casting vacuities they leave behind after cell decay; however, they may occasionally be preserved as three-dimensionally fossilized soft parts. Here we present brownish to rust-coloured microbodies, extracted from a Middle Triassic (ca. 245 Ma) bone of the reptile Nothosaurus, which are morphologically consistent with bone cells of present-day vertebrates. In situ imaging shows that these structures, which are reminiscent of bone cells, are harboured in lacunae framed by the bone matrix. Chemical characterization using energy-dispersive X-ray, Raman, and X-ray photoelectron spectroscopy revealed the presence of various phases of iron oxide mineralization. The predominant mineral phases are hematite and goethite; magnetite and maghemite appear to occur sporadically. It is not clear how these nanograined mineral phases were formed. Most likely mineralization proceeded very early and was triggered by local microenvironmental conditions favouring the precipitation of iron phases. The absence of a distinct signal indicating organic molecules suggests that the original bone cells underwent autolysis or other degradative processes before or during mineralization.

Influence of chemical fixation process on primary mesenchymal stem cells evidenced by Raman spectroscopy

In investigation of (patho)physiological processes, cells represent frequently used analyte as an exceptional source of information. However, spectroscopic analysis of live cells is still very seldom in clinics, as well as in research studies. Among others, the reasons are long acquisition time during which autolysis process is activated, necessity of specified technical equipment, and inability to perform analysis in a moment of sample preparation. Hence, an optimal method of preserving cells in the existing state is of extreme importance, having in mind that selection of fixative is cell lineage dependent. In this study, two commonly used chemical fixatives, formaldehyde and methanol, are used for preserving primary mesenchymal stem cells extracted from periodontal ligament, which are valuable cell source for reconstructive dentistry. By means of Raman spectroscopy, cell samples were probed and the impact of these fixatives on their Raman response was analyzed and compared. Different chemical mechanisms are the core processes of formaldehyde and methanol fixation and certain Raman bands are shifted and/or of changed intensity when Raman spectra of cells fixed in that manner are compared. In order to get clearer picture, comprehensive statistical analysis was performed.