In this paper, a micromechanical framework for modeling the rate-dependent response of unidirectional composites subjected to off-axis loading is introduced. The model is intended for a thin slice ...representative volume element that is oriented perpendicular to the reinforcement of the composite material. The testing conditions from a uniaxial off-axis test are achieved by a dedicated strain-rate based arclength formulation. The constraint equation of the arclength model is constructed such that the deformation state of the micromodel, as imposed in its local coordinate system, corresponds to the strain-rate applied on the material in global frame of reference. The kinematic description allows for finite strains in the material, meaning that the micromodel changes orientation during the deformation process. This geometric nonlinear effect is also included in the evaluation of external loading, ensuring that the external forces are equivalent to the applied off-axis stress in global coordinate system. Several examples are considered in order to show that the model resolves rate-dependency of the material, accounts for different off-axis loading, and captures finite strains exactly. Additionally, a small strain version of the model is derived from the general nonlinear framework. Results obtained with this simplified approach are compared to results of the large deformation framework.
In this paper we develop a finite deformation micromechanical framework for modeling rate-dependent failure in unidirectional composites under off-axis loading. The model performance is compared with ...original experiments on thermoplastic carbon/PEEK composites tested at different strain-rates and off-axis angles. To achieve quantitative agreement with the experiments, a microcrack initiation criterion based on the local stress and the local rate of deformation state in the polymer matrix is proposed. Microcracking is represented by a cohesive zone model, with special attention to the inclusion of geometric nonlinearity in the formulation. In this regard, the cohesive geometric nonlinearity is based on extension of an existing formulation to three-dimensional space. Beside microcracking, the Representative Volume Element (RVE) also accounts for viscoplasticity in the polymer matrix. A recently introduced dedicated arclength control method is utilized to impose a strain-rate on the micromodel. Accordingly, kinematic relations governing the RVE deformation allow for the change in orientation of the micromodel in the loading process. This change in orientation of the microstructure has an important implication on the apparent material strength.
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•An RVE model to study failure in UD composites undergoing finite strains is developed.•The model is compared with original experiments on UD carbon/PEEK composite system.•Microcrack initiation based on the polymer deformation rate is proposed.•An arclength model imposes strain-rate on the RVE under an arbitrary off-axis angle.
The aim of this study was to determine ochratoxin A (OTA) concentrations in the raw materials and cooked meat products made from pigs sub-chronically exposed to OTA. The treated animal group (n=5) ...was administered with 300μg OTA/kg of feed for 30days, whereas the control group (n=5) was left untreated. OTA concentrations were quantified using immunoassay (ELISA) and high performance liquid chromatography with fluorescence detection (HPLC-FD). OTA concentration was the highest in the kidney, followed by the lungs, liver, blood, spleen, heart, and adipose tissue. As for the final meat products, the highest average OTA concentration was detected in black pudding sausages (14.02±2.75μg/kg), then in liver sausages (13.77±3.92μg/kg), while the lowest was found in pâté (9.33±2.66μg/kg). The results pointed out that a sub-chronic pig exposure leads to the accumulation of OTA in raw materials and consequently in meat products, whose level of contamination is directly dependent on OTA contents in raw materials used for their production.
•OTA in raw materials and meat products made from treated pigs were determined.•ELISA and HPLC-FD methods were used.•OTA was the highest in the kidney and the lowest in adipose tissue.•The highest OTA was detected in black pudding sausages and the lowest in pâté.•Meat products contamination is directly dependent on OTA contents in raw materials.
The aim of the study was to investigate OTA contamination of “Slavonski Kulen” during a six-month production process. Raw meat & spices (n = 7) used with the production and final products with either ...intact or damaged casings (n = 99) were sampled on the production day 30, 60, 90, 120, 150 and 180, and analysed for OTA presence using an enzyme-linked immunosorbent assay (ELISA) and high performance liquid chromatography with fluorescence detection (HPLC-FLD). No statistically significant differences (p > 0.05) were observed among the intact samples on any above-given production day, the maximal OTA value attributable to raw material contamination thereby being 3.18 μg/kg. As for the damaged samples, the mean OTA concentration established on the production day 180 was 7.92 ± 6.50 μg/kg, while the maximal observed OTA value equalled to 17.0 μg/kg. The results demonstrated that casing damaging witnessed during a long-term dry-cured meat products' ripening can result in OTA entry from the surface into the product, causing a significant OTA contamination.
•OTA in “Slavonski Kulen” during a six-month production process was investigated.•Raw meat, spices and final products with intact or damaged casing were analysed.•ELISA and HPLC-FLD were implemented.•Casing damaging during a long-term ripening can result in OTA contamination.
Traditional meat products are commonly produced in small family businesses. However, big industries are also involved in the production of this kind of product, especially since a growing number of ...consumers crave the traditional taste and aromas. The popularization of original and organic products has resulted in a return to traditional production methods. Traditional meat products are produced worldwide. However, in such (domesticated) conditions there is a potential danger for mycotoxin contamination. This review aims to present the sources of mycotoxins in traditional meat products, the most common mycotoxins related to such meat products, and future prospects regarding the suppression of their occurrence. Special attention should be paid to reducing the transfer of mycotoxins via the food chain from animal feed to animals to humans (stable-to-table principle), which is also described in this review. Other sources of mycotoxins (spices, environment, etc.) should also be monitored for mycotoxins in traditional production. The importance of monitoring and regulating mycotoxins in meat products, especially in traditional meat products, is slowly being recognized by the institutions and hopefully, in the future, can deliver legally regulated limits for such products. This is especially important since meat products are available to the general population and can seriously affect human health.
•Naphthalene, acenaphthylene, acenaphthene, fluorene, anthracene and phenanthrene in all samples of Slavonska kobasica.•Highest PAH content was found in traditionally smoked sausages closer to open ...fire.•Industrially smoked sausages in collagen casing had smaller amounts of total PAHs.•Type of casing and distance from the open fire highly affect PAH concentrations.•Collagen casing gave lower PAH levels than natural casing.
The aim of this study was to determine the content of 16 polycyclic aromatic hydrocarbons (PAHs) in the traditional dry fermented sausage Slavonska kobasica. Smoking was conducted in a traditional smokehouse (two and three-metre distances from the open fire) and in an industrial chamber. Two different casings were also applied: natural and collagen. PAHs were determined at the end of the smoking phase and at the end phase of the whole production process. The highest total content of the 16 PAHs was determined in sausages stuffed in natural casings and smoked in a traditional smokehouse (two metre distance from the open fire) at both examined periods (509 μg/kg; 679 μg/kg respectively). The use of a collagen casing and an industrial chamber resulted in the lowest content of the 16 PAHs (114 μg/kg; 124 μg/kg respectively). Possibly carcinogenic benzaanthracene was found in sausages stuffed in natural casings and smoked in traditional conditions, but the values remained below the legal concentration limit of 30 μg/kg for PAH4 (EC No. XX/2019). The benzoapyrene content in all samples was also below the limit of quantification, staying well below the EU legislation prescribed value (5 μg/kg).
This research aimed to investigate the effect of the addition of wet brewers’ spent grains (BSG) on the microbiological safety, and physicochemical and sensory attributes of “bijela krvavica” during ...seven-day storage at 4 °C. The addition of BSG to the samples of “bijela krvavica” statistically significantly (p < 0.05) affected the mass share of proteins and fat and increased the mass share of water. Increasing the mass share of BSG in “bijela krvavica” did not have a statistically significant (p < 0.05) effect on the mass share of collagen, or on the pH value and aw. Instrumentally determined lightness (L*), redness (a*), and yellowness (b*) showed a decrease with the increase in mass share of wet BSG. Texture profile analysis (TPA) parameters hardness and chewiness also showed a decrease with the increase in BSG share (w = 0–9%) with statistical significance (p < 0.05). The overall liking of “bijela krvavica” samples showed the highest scores for the control sample, while 3% added BSG was rated as second best with no significant difference (p < 0.05). According to the consumer-generated sensory attributes (CATA) scoring, samples with 6 and 9% addition of BSG were described with attributes considered undesirable for meat products, such as “wheaty”, “pale color”, and “poor mouthfeel”. Also, the LogCFUg−1 of enterobacteria, sulfite-reducing clostridia, Staphylococcus aureus, Salmonella spp., and Listeria monocytogenes were not affected. The data obtained in this research indicate the possibility of producing safe “bijela krvavica” sausages with wet brewers’ spent grains without major changes in the physicochemical and sensory properties.
Kilning is an integral part of malt production; it ensures grain and enzyme preservation. Kilning temperatures can range between 80 and 220 °C, depending on the type of malt that is being produced. ...Polycyclic aromatic hydrocarbons (PAHs) are prone to appear at higher temperatures and are generally designated as undesirable in food and beverages. Sixteen PAHs are framed in legislation, but there is a lack of scientific data related to PAHs in malt, malt-related foods (bread, cookies) and beverages (whisky, malted non-alcoholic beverages). The aim of this paper was to assess and quantify the occurrence of different PAHs in malts exposed to different kilning temperatures (50-210°) over a variable time frame. The results indicate that some of the PAHs detected at lower temperatures disappear when malt is exposed to high temperatures (>100 °C). Phenanthrene was no longer detected at 100 °C and indeno 1,2,3-cd pyrene at 130 °C, while fluorene, anthracene and benzo (a) anthracene were not quantified at 170 °C. The results of this research can be implemented in food safety legislation since foods available to children utilize malted flour (bread, cookies, bakery goods, etc.) due to its enzymatic activity or as a colour additive.
Thyme, mint, and lemon balm were used to determine whether shading conditions could improve the yield, composition, antioxidant, and antimicrobial activity in plant essential oils (EOs) in comparison ...with non-shaded plants from an open field. The yield of the EOs of non-shaded thyme, mint, and lemon balm, was 3.44, 3.96, and 0.21 mL/100 g, respectively. Plants covered by nets produced different levels of EOs (3.46, 2.20, and 0.45 mL/100 g) after 120 min of hydrodistillation. The main components of the thyme essential oil are thymol (44.2–43.9%), γ-terpinene (18.3–16.8%), and p-cymene (16.5–17.4%). The predominant components of mint essential oil are piperitenone oxide (52.6–64.8%) and 1,8 cineole (25.9–16.3%), while lemon balm essential oil consists of the following main components: geranial (34.0–32.8%); neral (21.3–24.9%); and piperitenone oxide (17.2–16.7%). The EOs from non-shaded thyme and mint plants have the highest antioxidant activity (EC50 value 0.54 mg/mL and 3.03 mg/mL). However, shaded lemon balm showed a stronger antioxidant activity (EC50 3.43 mg/mL) than non-shaded plants (12.85 mg/mL) after 60 min of incubation. The EOs from all plants showed significant effects against Escherichia coli, Proteus vulgaris, Bacillus subtilis, Staphylococcus aureus, and Candida albicans. The most active EOs against most of the isolates originated from Thymus vulgaris L., plants. Adequate cultivation techniques, such as shading for Lamiaceae plants, has positive effects, especially in Melissa officinalis L. Shading can achieve a higher content and components in terms of the specific biological activity (antioxidant and microbial) of EOs.
