Acid Value Research Articles

Volatile compounds and quality changes of lesser mealworm larvae: effect of blanching, storage temperature and time

Abstract The impact of blanching and storage temperature (−20 °C and −80 °C) on the formation of volatile organic compounds and changes in quality characteristics of lesser mealworm (Alphitobius diaperinus) larvae was examined over seven weeks. Acid and peroxide values, pH, and colour of lesser mealworm larvae were significantly affected by the studied variables. The changes in these characteristics as well as in the volatile profile indicated occurring lipid oxidation and lipid hydrolysis processes during the storage. The intensity of these reactions was mostly influenced by blanching treatment and storage time, and a lesser extent by storage temperature. It was proposed that changes in composition and intensity of volatiles can be used for rapid quality assessment of lesser mealworm larvae during frozen storage. Thus, the selection of optimum storage conditions for lesser mealworm larvae is important for the prevention of undesirable chemical reactions and preservation of the quality of insect biomass.

Methyl Ester Production from Rice Bran Oil and Methanol with Calcium Carbonate Catalysts Using Esterification Method

Rice bran oil is a type of oil with high nutritional value from rice bran. However, the free fatty acid content in it can increase by more than 60% with sufficient storage time. Free fatty acids contained in rice bran have the potential to be produced into biodiesel (methyl ester). This research aimed to determine the effect of methanol volume and esterification process time on biodiesel yield and to compare methyl ester yield to standard biodiesel. This research was conducted in two stages, namely rice bran oil extraction and esterification. In the extraction stage, rice bran was extracted with n-hexane for 3 hours at an operating temperature of 65oC. The esterification process was carried out by mixing rice bran oil, methanol with a certain volume (100, 125, 150, 175, 200 mL), and calcium carbonate catalyst as much as 1% of the amount of methanol. Esterification was carried out with time variations of 1; 1.5; 2; 2.5 and 3 hours. The results in the form of rice bran oil were analyzed for the value of the biodiesel yield. The result of rice bran oil was analyzed for initial free fatty acid value. Pure biodiesel product in the form of methyl ester was obtained through separation with glycerol as a by-product. The optimum methyl ester yield was 81.70% at 175 ml methanol volume for 3 hours. The methyl ester results are in accordance with SNI biodiesel for density and kinematic viscosity values.

Environmental assessment of soluble solids contents and pH of orange using hyperspectral method and machine learning

Progress in non-destructive methods to detect the characteristics of fruits is a new and attractive process for researchers and specialists in this field. On the other hand, these researchers move toward identifying their impacts on their surroundings in line with diagnostic efficiency. One of these essential impacts is the environmental impact of the non-destructive detection process of fruits. Navel oranges are one of the most popular and widely consumed fruits, whose maturity indices such as soluble solids contents (SSC) values and acidity are considered as parameters in determining the quality of this product. This study used the hyperspectral method in the vis-NIR range to evaluate and measure navel oranges' SSC and acidity values. In the following, by applying the life cycle assessment method, the environmental impacts of measuring and evaluating these two parameters of the characteristics of navel oranges were investigated. The Impact2002+ method was used to evaluate the impact of the life cycle list. Based on the findings, the environmental impacts of SSC measurement are about 40, 42, 20, and 18 % higher than those of the environmental impacts of pH measurement from the point of view of endpoint impacts for Human Health, Ecosystem quality, climate change, and resources, respectively. The random forest modeling results showed a suitable and acceptable correlation and relationship (over 90 %) between the wavelengths selected from the feature selection stage and environmental impacts.

Formulation of a stable diesel microemulsion using eco-friendly ionic liquids and investigation of particle size and fuel properties as an alternative fuel

Ecofriendly ionic liquids (ILs) were synthesized through amidation of ricinoleic acid, the main fatty acid in castor oil, followed by a quaternization reaction to solubilize ethanol in IL/diesel blends at different ratios. As a result, stable and highly renewable, low viscous microemulsion biofuels with high oxygen content were prepared. The prepared fuel samples combine the advantages of green ionic liquids and microemulsion properties. The chemical structures of ILs were confirmed with the aid of NMR and FTIR spectroscopy. DLS analysis revealed that the ethanol particles ranged in size from 8 to 18.1 nm in all samples. As ILs ratios decrease in microemulsion from 37 to 69%, the ethanol particle sizes increase from 10 to 25%. Ethanol shows good solubilization in diesel and IL-1 is more effective than IL-2 in ethanol solubilization at low percentages of ethanol due to more oxygen atoms besides three hydroxyl groups. The ternary phase diagram indicated that the microemulsion area in the case of using IL-1 is larger than that of IL-2. The fuel properties of the prepared microemulsions are nearly close to those of neat diesel and fall within the permitted range of ASTM D975. The viscosity and density values at low ratios of ILs are found to be very close to the values of the neat diesel at different temperatures. The prepared samples show a slight decrease in cetane number and heating value compared to diesel. However, they have improved flash points, cloud points, sulfur content, and acid value. The particle sizes were checked every week and the prepared samples showed high stability with the aid of the synthesized ILs. Moreover, the prepared microemulsions stayed in a transparent appearance for more than a year and no phase separation was observed.

Utilizing Nano-Adsorbents and Electrostatic Field Treatment for Sustainable Refinement of Crude Canola Oil.

Removal of polar impurities, such as phospholipids, free fatty acids (FFA), and peroxides, can be challenging during the refining of crude canola oil. Current conventional refining methods are energy-intensive (e.g., hot water washes) and can generate significant waste (e.g., wastewater effluent) and neutral oil loss. This study investigated the joint use of nano-adsorbents and electrostatic field (E-field) treatment as a potential and sustainable alternative in removing these impurities during the oil refining process. Specifically, aluminum oxide (Al2O3) nanoparticles were employed to neutralize FFAs, achieving a 62.4% reduction in acid value while preserving the fatty acid profile of the oil. After refining, E-field treatment was successful in removing the spent nano-adsorbent from solution (up to 72.3% by weight), demonstrating enhanced efficiency compared to conventional methods (e.g., gravitational settling, filtration, and centrifugation). The neutral oil loss using Al2O3 nano-adsorbents was also comparable to conventional refining methods, with a 4.38% (by weight) loss. After E-field treatment, the Al2O3 nano-adsorbent was then calcined to assess reusability. The Al2O3 nano-adsorbent was effectively recycled for three refining cycles. the methods do not use of large amounts of water and generate minimal waste byproducts (e.g., effluent). Nonetheless, while the nano-adsorbents demonstrated promising results in FFA removal, they were less effective in eliminating peroxides and pigments. E-field techniques were also effective in removing spent nano-adsorbent; although, optimization of E-field parameters could further improve its binding capacity. Finally, future studies could potentially focus on the physicochemical modifications of the nano-adsorbent material to enhance their refining capacity and reusability. Overall, this study presents a sustainable alternative or addition to conventional refining methods and lays the groundwork for future research.

Fourier-Transform Infrared Spectroscopy and Gas Chromatography-Mass Spectrometry Characterization of Arachis Oil for Production of Laundry Soap

The study aimed to extract oil from Arachis seeds (Arachis hypogaea), characterize the oil with FTIR and GC-MS, and use it to produce laundry soap. Arachis oil was extracted via the Soxhlet method in nhexane. Standard methods were adopted to examine the properties of the extracted oil, and the produced laundry soap. Fourier-Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS) were used to analyze the chemical composition of the oil. The results showed that 70.0 g of the Arachis seed gave 49.56±1.24 % oil yield. The physicochemical characterization of the oil showed that the relative density, saponification value, acid value, and iodine value were 0.65±0.15 g/mL, 190.74±2.17 mgKOH/g, 2.08±0.15 mgKOH/g, and 91.88±0.25 gI2/100g, respectively. Functional groups analysis from FTIR data revealed unique absorption peaks of methyl group at 1379 cm–1, methylene group at 723, 1461, 2847, 2922 cm–1, carbonyl group at 1744 cm–1, and olefin group at 1654 cm–1, which are attributed to the fatty acids present in the Arachis oil. The GC-MS analysis confirmed the following fatty acids: Oleic acid, Elaidic acid, and Vaccenic acid in the oil. The soap’s quality parameters determination offered 99.75±0.26 cm, 4.63±0.37 cm, 7.10±0.78 % and 59.25±2.65 % for pH, foam height, moisture content and total fatty matter, respectively. Besides, the soap was slightly pinkish and moderately hard. The findings of the study proved that Arachis seeds oil is a richsource of fatty acids with the required functional groups for efficient saponification reaction, and has a huge potential for large-scale production of quality laundry soap.

Physico-chemical changes in developed probiotic chicken meat spread fermented with Lactobacillus acidophilus and malted millet flour

This study was envisaged to develop a probiotic chicken meat spread fermented with Lactobacillus acidophilus (Lactic acid bacteria-LAB) and malted sorghum flour as a substrate and evaluation of its quality. Chicken meat spread was prepared by incorporating malted sorghum flour at 0, 2, 4 and 6 % (w/w) levels as a substrate in the product's formulation, along with Lactobacillus acidophilus at a concentration of 1 million cfu/g of the product. The product prepared with different formulations i.e. C (meat spread only), C1 (meat spread with 0 % malted sorghum flour + LAB), T1 (meat spread with 2 % malted sorghum flour + LAB), T2 (meat spread with 4 % malted sorghum flour + LAB) and T3 (meat spread with 6 % malted sorghum flour + LAB) were assessed for fresh product study and the storage stability at refrigeration temperature for 16 days when the physico-chemical parameters were analyzed. The fresh product study revealed significantly (p ≤ 0.05) higher moisture content in the T3 group. However, lower protein, ether extract, and ash content in T2 and T3 samples compared with the control, whereas a higher emulsion stability and cooking yield in the T2 group were observed when compared with the control. Free fatty acid, thiobarbituric acid, and titratable acidity values significantly (p ≤ 0.05) increased for the fermented samples in comparison to the control, and the same trend continued during the entire storage period. This study showcases the potential of using malted sorghum flour and Lactobacillus acidophilus to enhance the functional properties of chicken meat spreads, making them more nutritious and appealing to health-conscious consumers. Future research should focus on optimizing ingredient proportions and exploring alternative substrates to further improve these functional meat products.

Advances in synthesis of succinic acid using yeast cell factories

Succinic acid is an important C4 platform compound that serves as a raw material for the production of 1,4-butanediol, tetrahydrofuran, and biodegradable plastics such as polybutylene succinate (PBS). Compared to the traditional petrochemical-based route that uses maleic anhydride as a raw material, the microbial fermentation method for producing succinic acid offers more sustainable economic value and environmental friendliness. Yeasts with good acid tolerance can achieve low-pH fermentation of succinic acid, significantly reducing the cost of product extraction. Therefore, constructing high-yield succinic acid yeast strains through metabolic engineering has garnered increasing attention. This paper systematically introduced the application value and market size of succinic acid, summarized the pathways and key enzymes involved in succinic acid synthesis in microorganisms, and elaborated on the latest research progress in the synthesis of succinic acid using yeast cell factories. It also presented the current status of succinic acid synthesis using non-food raw materials such as glycerol, acetic acid, lignocellulosic hydrolysate, and others as substrates by engineered yeast strains. Finally, the paper provided a prospect for low-pH succinic acid biomanufacturing based on yeast cell factories.

Bioactive properties, phytochemicals, fatty acids, mineral contents and sensory characteristics of the breads prepared using wheat flour and nutmeg powders at different concentrations

SummaryIn this study, bioactive compounds, antioxidant activity, phytochemicals, fatty acid compositions, elements and sensory characteristics of the breads prepared using wheat flour and nutmeg powders at different concentrations were investigated. The results obtained regarding the physical and chemical properties of nutmeg breads exhibited some changes based on the nutmeg amounts added in bread production. Also, ‘L*’ results of the breads changed between 70.85 (1.0%) and 76.09 (0.5%). In addition, ‘a*’ and ‘b*’ results of breads with nutmeg powder were assigned to be between 0.47 (0.5%) and 1.93 (2.0%) to 18.44 (2.0%) and 20.42 (0.5%) and 1.93 (0.5%), respectively. Total phenol and flavonoid amounts of breads were established between 24.64 (0.5%) and 47.58 mg GAE per 100 g (2.0%) to 10.71 (control) and 177.38 mg per 100 g (2.0%), respectively. An increase in the redness value was monitored in nutmeg bread added at the rate of 1% and 2%. The amounts of phenolic constituents in the breads fluctuated depending on the added nutmeg concentrations. Gallic acid and 3,4‐dihydroxybenzoic acid values of the breads were stated to be between 2.66 (2.0%) and 6.66 mg per 100 g (1.0%) to 1.48 (2.0%) and 2.71 mg per 100 g (control), respectively. Phosphorus and potassium quantities of the breads were found between 743.60 (control) and 810.50 mg kg−1 (0.5%) to 2077.37 (1.5%) and 2345.42 mg kg−1 (0.5%), respectively. The dominant fatty acids in bread oils were myristic, palmitic, oleic and linoleic acids. It can be seen that the addition of nutmeg in high concentration decreased the consumer's taste. In addition, the added nutmeg increased the colour value of the bread and corrected the textural structure.

A global methanol-to-hydrocarbons (MTH) model with H-ZSM-5 catalyst acidity descriptors

This work presents a dual cycle-based kinetic model that uses H-ZSM-5 catalyst acidity descriptors for the methanol-to-hydrocarbons (MTH, -olefins, MTO, and –aromatics, MTA) processes. This model was developed using data obtained in 12 periodic reactions with three H-ZSM-5 zeolites of different acidity (Si/Al = 15, 40 and 140). We decoupled the kinetics of the model from the catalyst identity by linking the calculation of the kinetic parameters to the zeolite acidity, allowing us to perform simulations of the reactor operating under various conditions and with different zeolite acidity values different from those used experimentally. The results obtained in the simulations let us identify the best operating conditions for the MTO and MTA processes, and pointed at the main difficulties found when implementing these two technologies industrially. In addition, the conditions and values obtained for the target products, either light olefins or aromatics, were comparable with those presented by several existing works in the literature for H-ZSM-5 zeolites of similar acidity. Moreover, the methodology detailed here using acidity descriptors can be extrapolated for its application to other catalytic processes.

Assessment of acute, subacute genetic toxicities and immunomodulatory activity of palm (Trachycarpus fortunei) buds

Ethnopharmacology relevancePalm buds are a natural green resource of the forest, which are not only rich in nutrients but contain a large number of phenolic acids and flavonoids, among other components. It has a variety of biological activities such as antioxidant and uterine smooth muscle stimulation.Aim of the study: To evaluate the safety of palm buds for use as a nutraceutical product and food by evaluating the toxicity, subacute toxicity and genotoxicity of the young palm buds. Also studied for its immune-enhancing activity. Materials and methodsAcute toxicity tests were performed in mice using the maximum tolerance method, and the manifestations of toxicity and deaths were recorded after administration of 10,000 mg/mL for 14 consecutive d (days) of observations. To assess subacute toxicity, mice were treated with palm buds (750, 1500, or 3000 mg/mL) daily for 28 days. The teratogenicity of palm buds was assessed by the Ames test, the mouse bone marrow cell micronucleus test, and the mouse spermatozoa malformation test. In addition, we evaluated the immune-enhancing ability of palm buds by the mouse carbon profile test, delayed-type metamorphosis reaction, and serum hemolysin assay. ResultsIn the acute toxicity study, the Median Lethal Dose (LD50) was greater than 10,000 mg/kg bw in both male and female rats. There were also no deaths or serious toxicities in the subacute study. The no-observed-adverse-effect level (NOAEL) was 3000 mg/kg bw. However, the mice's food intake decreased after one week. The medium and high dose groups had a reducing effect on body weight in mice of both sexes. In addition, the changes in organ coefficients of the liver, kidney and stomach in male mice were significantly higher in the high-dose group (3.23 ± 0.35, 0.75 ± 0.05, 0.57 ± 0.05 g) than in the control group (2.94 ± 0.18, 0.58 ± 0.05, 0.50 ± 0.02 g). Hematological analyses showed that all the indices of the rats in each palm sprout dose group were within the normal range. The results of blood biochemical indicators showed that there was a significant reduction in TP in the blood of male mice in the high-dose group (44.6 ± 7.8 g/L) compared to the control group (58.3 ± 15.1 g/L). In histopathological analysis, none of the significant histopathological changes were observed. The results of the immunological experiment in mice showed that the liver coefficient and thymus coefficient of the high-dose group (8400 mg/kg) were significantly lower than the control group. There was no remarkable difference in auricle swelling between each dose palm bud group (1400, 2800, or 8400 mg/kg) and the control group. The anti-volume number of the high-dose group was significantly increased. ConclusionPalm buds have non-toxic effects in vivo and have little effect on non-specific and cellular immunity in the test mice within the dose range of this experiment. The immunoenhancement in mice is mainly achieved through humoral immunity. In conclusion, our results suggest that palm buds are safe for use as healthcare products and food.

Drying kinetics of camellia oleifera seeds under hot air drying with ultrasonic pretreatment

Camellia oleifera seeds with high moisture content are prone to decay, leading to oil rancidity and seriously affecting subsequent processing and tea oil quality. Thus, an efficient drying method is needed. Hot air drying with ultrasonic pretreatment is a potential drying method for camellia oleifera seeds. In this paper, the effects of key parameters such as ultrasound power, ultrasound pretreatment time, and hot air drying temperature on the moisture ratio of camellia oleifera seeds, as well as the changes in microstructure of both seed shell and seed kernel, and the main quality parameters such as peroxide value and acid value of tea oil were explored. Results showed that the shorter the ultrasound pretreatment time, the greater the ultrasound power, the higher the temperature, the faster the drying rate, and the shorter the drying time. The drying time and specific energy consumption was reduced by up to 26.7 % and 16.8 % with the ultrasonic pretreatment, respectively. The optimal ultrasonic pretreatment time is 2 min, and the ultrasonic power is 300 W. A Genetic Algorithm Optimized Backpropagation Artificial Neural Network (GA-BP-ANN) drying model was proposed to predict the changes in moisture ratio during the drying process of camellia oleifera seeds to provide guidance for the development of intelligent drying system. The experimental results showed that the proposed drying model had a good predictive performance, with an RMSE of 0.0076969 and an R2 of 99.909 %, which can accurately estimate the effect of ultrasonic pretreatment on hot air drying. The research results of this study are expected to reduce post-harvest losses of camellia oleifera fruits and provide theoretical support for the development of drying systems of camellia oleifera seeds and similar agricultural products.

Conversion of soybean oil under subcritical water conditions into liquid biofuels with low oxygen contents

Although the hydrotreatment of natural triglycerides is a well-established route for producing sustainable aviation fuel and renewable diesel, its high hydrogen consumption is a concern. The hydrothermolysis of natural triglycerides is considered a highly promising alternative route; however, the correlation between process parameters and fuel properties and detailed chemical structures of the produced fuel have not been established. Herein, we investigated the conversion of soybean oil to gasoline-, jet fuel- and diesel-fraction hydrocarbons with low oxygen contents. The properties of fuels produced under various reaction conditions were analyzed comprehensively using simulated distillation, total acid number (TAN), and elemental analysis. Under the optimized reaction conditions of 420 °C, 4.5 MPa, an oil-to-water ratio of 6:1, and reaction time of 10 min, 26 % gasoline-, 62 % jet fuel-, and 90 % diesel-range hydrocarbons with a low oxygen content of 5.1 %, low TAN of 0.04 mg KOH g−1, and high calorific value of 42.7 MJ kg−1 resulted. To elucidate the reaction mechanism, the liquid products produced from soybean oil were analyzed using comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry. In addition, based on the oleic acid conversion under varying hydrothermal conditions, we proposed deoxygenation, cracking, cyclization, and aromatization pathways. The findings of this study present possibilities for producing sustainable biofuels with low oxygen contents for the aviation industry.

Waste Point Identification of Frying Oil Based on Gas Chromatography-Ion Mobility Spectrometry (GC-IMS).

This study described the quality detection and rapid identification of frying oil waste points based on gas chromatography-ion mobility spectrometry (GC-IMS). A total of 48 volatile substances were identified, among which the levels of 11 components, including 2-pentylfuran, 2-butylfuran, and 2-hexanone, increased with prolonged frying time after 40 h in cottonseed oil. Conversely, the levels of hexanal, heptanal, and E,E-2,4-heptadienal decreased as frying time extended. Correlation analysis revealed a significant association between volatile substances of the oil and acid value (p < 0.05) and polar components with volatile substances (p < 0.05). Furthermore, significant differences in the types and contents of flavor substances were observed in cottonseed oil at different frying times (including before and after reaching the discard point) (p < 0.05). Subsequently, principal component analysis (PCA) results clearly showed that the cottonseed oil samples at different frying times were well distinguished by the volatile compounds; moreover, discriminant model analysis indicated a model accuracy rate of 100%. These results showed the potential of GC-IMS-based approaches in discriminating the waste points of frying oil.

Stability of Pure Biodiesel (B100), Biodiesel Mixture (B40), and Petroleum Diesel (B0) Due to Storage

Biodiesel is produced from synthetic ester compounds of vegetable and animal oils through a process of refining, bleaching, degumming, transesterification, and esterification. The quality and characteristics of the fuel are greatly influenced by the storage. The purpose of this research is to determine and analyze the effect of storage conditions on the physical and chemical changes of biodiesel (B100), biodiesel blend (B40), and petro diesel (B0). Experiment was conducted by storage fuels using glass bottle for 35 days arranged into four conditions based on cap and wrapping using aluminum foil, namely P1 (with cap, with wrapping), P2 (with cap, no wrapping), P3 (no cap, with wrapping), and P4 (no cap, no wrapping). Results showed that fuel quality decreases due to storage indicated by an increase in water content, density, acid number, and color parameters, as well as a decrease in the specific calorific value of all fuels. The condition of the storage container affected the changes the quality parameters. Based on its impact on fuel quality decline, the order of storage container conditions from the best is P1 (with cap, with wrap) &gt; P2 (with cap, no wrap) &gt; P3 (no cap, with wrap) &gt; P4 (no cap, no wrap). Keywords: Biodiesel, Biodiesel blend (B40), Diesel fuel, Stability, Storage time.

Evaluation of dietary supplementation of garlic powder (Allium sativum) on the growth performance, carcass traits and meat quality of Japanese quails (Coturnix coturnix japonica)

Dietary supplementation with plant-based products may arise as part of an alternative strategy to using antibiotics as growth promoters in the poultry industry. Garlic powder (GP) possesses antimicrobial and antioxidant properties. The aim was to investigate the effect of dietary supplementation of GP on growth performance, carcass traits and meat quality of the Japanese quail. A total of 240, day-old mixed gender Japanese quail were assigned to 4 treatment groups, each group being replicated 4 times and containing 15 birds in each replication. Birds were provided with either a basal diet (control) or basal diet supplemented with 0.5%, 1% and 2% GP for 5 wk. At slaughter age, birds fed 1% GP had higher (P < 0.05) live weight and body weight gain when compared to the control. Supplementation with different levels of GP had no influence (P > 0.05) on feed intake, feed conversion ratio except 3rd wk, carcass traits and abdominal fat. Thiobarbituric acid, peroxide and pH values in breast meat of birds receiving GP (1% or 2%) after storage (0, 1, 3, 5, and 7 d) were lower (P < 0.05) than the birds in control. Furthermore, total psychrophilic bacteria count was lower in breast meat of birds supplemented with GP at any dose compared to the birds of control. Sensory characteristics such as color, aroma, juiciness and tenderness were observed significantly better (P < 0.05) in GP supplemented groups especially when fed 1% GP. In conclusion, supplementing the diet with 1% to 2% GP demonstrated growth-promoting effects and positively impacted meat quality, including sensory characteristics.

Contribution to the analysis of the physico-chemical and rheological degradation of 15w40 lubricating oils for the optimization of drain intervals

Degradation of engine oil can lead to a reduction in its effectiveness in reducing friction, which has a negative impact on engine durability and performance. This research examined in detail the physico-chemical and rheological properties of new and used motor oils, divided into three groups (A, B and C) and subjected to different driving distances (0 km, 4000 km and 7000 km). The main findings include: Progressive degradation of kinematic viscosity at 40°C with increasing distance travelled, with greater degradation in group A. A similar degradation in kinematic viscosity at 100°C, with Group A showing the greatest degradation, suggesting a loss of efficiency at higher temperatures. A progressive decrease in viscosity index with increasing distance travelled. Significant changes in the total acid number (TAN) and total base number (TBN) of the oil with increasing distance travelled, with the greatest decrease in TBN observed in group C, suggesting acidification of the used oil. A progressive decrease in the sulfur content of used oil compared to new oil, mainly in group C. A progressive deterioration in dynamic viscosity with increasing distance travelled, particularly at higher temperatures. These results highlight the importance of regular maintenance and servicing of thermal engine lubricating oils particularly in an urban driving. future work Develop a predictive model using neural networks to analyze physical, chemical, and rheological properties, and monitor it online.

Reduction of oxidative rancidification of fungal melanin-coated films in pork lard preservation in trading.

Storage of meat has always been challenging due to its deterioration caused by oxidative rancidity and microbial activity, especially in trading. The melanin-coated film acts as a potent antioxidant, prevents the oxidation of fatty acids, and neutralizes the reactive oxygen species (ROS) helping to withstand or perpetuate the oxidative stress of meat. This study emphasizes the production of fungal melanin extracted from Curvularia lunata and the preparation of two different melanin film combinations of gelatin/melanin and agar/melanin at 0.1% and 0.5% formulation for rancidity stability of coated pork lard. Interpretations revealed the delayed rancidity in both peroxide and acid values with 5.76% in 0.5% agar-coated melanin up to the 11th day which was supported by arithmetical analysis showing p < 0.05 are statistically significant. Further, upon testing the brine shrimp assay for melanin toxicity, 7% were in a mortal state at 1000 µg/mL concentration, considered zero lethality. This result implies that modified coatings, particularly when trading meats, that include fungal melanin can effectively prevent the oxidation of pork lard.

Building microbial consortia to enhance straw degradation, phosphorus solubilization, and soil fertility for rice growth

Straw pollution and the increasing scarcity of phosphorus resources in many regions of China have had severe impacts on the growing conditions for crop plants. Using microbial methods to enhance straw decomposition rate and phosphorus utilization offers effective solutions to address these problems. In this study, a microbial consortium 6 + 1 (consisting of a straw-degrading bacterium and a phosphate-solubilizing bacterium) was formulated based on their performance in straw degradation and phosphorus solubilization. The degradation rate of straw by 6 + 1 microbial consortium reached 48.3% within 7 days (The degradation ability was 7% higher than that of single bacteria), and the phosphorus dissolution rate of insoluble phosphorus reached 117.54 mg·L− 1 (The phosphorus solubilization ability was 29.81% higher than that of single bacteria). In addition, the activity of lignocellulosic degrading enzyme system was significantly increased, the activities of endoglucanase, β-glucosidase and xylanase in the microbial consortium were significantly higher than those in the single strain (23.16%, 28.02% and 28.86%, respectively). Then the microbial consortium was processed into microbial agents and tested in rice pots. The results showed that the microbial agent significantly increased the content of organic matter, available phosphorus and available nitrogen in the soil. Ongoing research focuses on the determination of the effects and mechanisms of a functional hybrid system of straw degradation and phosphorus removal. The characteristics of the two strains are as follows: Straw-degrading bacteria can efficiently degrade straw to produce glucose-based carbon sources when only straw is used as a carbon source. Phosphate-solubilizing bacteria can efficiently use glucose as a carbon source, produce organic acids to dissolve insoluble phosphorus and consume glucose at an extremely fast rate. The analysis suggests that the microbial consortium 6 + 1 outperformed individual strains in terms of both performance and application effects. The two strains within the microbial consortium promote each other during their growth processes, resulting in a significantly higher rate of carbon source consumption compared to the individual strains in isolation. This increased demand for carbon sources within the growth system facilitates the degradation of straw by the strains. At the same time, the substantial carbon consumption during the metabolic process generated a large number of organic acids, leading to the solubilization of insoluble phosphorus. It also provides a basis for the construction of this type of microbial consortium.

Kinetic characterization of two neuraminic acid synthases and evaluation of their application potential

Neuraminic acid synthases are an important yet underexplored group of enzymes. Thus, in this research, we performed a detailed kinetic and stability analysis and a comparison of previously known neuraminic acid synthase from Neisseria meningitidis, and a novel enzyme, PNH5, obtained from a metagenomic library. A systematic analysis revealed a high level of similarity of PNH5 to other known neuraminic acid synthases, except for its pH optimum, which was found to be at 5.5 for the novel enzyme. This is the first reported enzyme from this family that prefers an acidic pH value. The effect of different metal cofactors on enzyme activity, i.e. Co2+, Mn2+ and Mg2+, was studied systematically. The kinetics of neuraminic acid synthesis was completely elucidated, and an appropriate kinetic model was proposed. Enzyme stability study revealed that the purified enzyme exhibits changes in its structure during time as observed by differential light scattering, which cause a drop in its activity and protein concentration. The operational enzyme stability for the neuraminic acid synthase from N. meningitidis is excellent, where no activity drop was observed during the batch reactor experiments. In the case of PNH5, some activity drop was observed at higher concentration of substrates. The obtained results present a solid platform for the future application of these enzymes in the synthesis of sialic acids.Key points• A novel neuraminic acid synthase was characterized.• The effect of cofactors on NeuS activity was elucidated.• Kinetic and stability characterization of two neuraminic acid synthases was performed.Graphical