Proportion Of Acids Research Articles

Amino acid composition and angiotensin-i converting enzyme inhibitory activity of Cowpea (<i>Vigna unguiculata</i>) pepsin-pancreatin protein hydrolysate fractions

Legumes are high in protein and have been linked to the management and prevention of chronic diseases due to their bioactive components. This study investigated the amino acid composition of cowpea protein hydrolysate and its inhibitory impact on angiotensin-I converting enzyme (ACE-I). Cowpea (Vigna unguiculata) protein hydrolysate (CPH) was produced through sequential digestion with pepsin and pancreatin. CPH was then separated using G-50 gel filtration chromatography and reverse phase high performance liquid chromatography (RP-HPLC). The fractions' ACE-I inhibitory activity was then assessed. The IC50 value for the RP-HPLC fraction with the highest ACE-I inhibitory activity (P<0.05) was 6.23 μg/mL. The amino acid profile revealed that a large proportion of hydrophobic amino acids were present in the RP-HPLC fraction containing the peptide with the highest ACE-I inhibitory activity. These findings suggest that CPH has the potential to be employed in the development of functional foods that can aid in the prevention and treatment of hypertension.

Integration of hyperspectral imaging, non-targeted metabolomics and machine learning for vigour prediction of naturally and accelerated aged sweetcorn seeds

Understanding and predicting the storage stability of sweetcorn seeds is critical for effective supply chain management, however, prediction ability relies heavily on accelerated ageing (AA) studies and this is not always directly applicable to natural ageing (NA). In this study, hyperspectral imaging (HSI) and non-targeted metabolomics (LC-MS/MS) were integrated using PLS-R, SVM-R and OPLS-DA to predict loss of seed vigour in NA seeds, using data based on AA seeds. The inconsistencies in the pattern of spectral variation between seeds undergoing AA and NA were first identified. AA-based vigour prediction models were then built using all wavelengths and effective wavelengths (EWs) selected by regression coefficients. These models were externally validated by independent AA and NA seed datasets, respectively. The results yielded satisfactory predictions for AA seeds (R2 ≥ 0.814), but low precision for NA seeds (R2 ≤ 0.696). Metabolome analysis identified 54 differential metabolites, containing a large proportion of amino acids, dipeptides and their derivatives, which were important substances reflecting discrepancies between the ageing mechanisms of AA and NA seeds. Subsequently, N-H bond-related wavebands were deemed to be a possible interference factor in the models' practicability. After removing the N-H bond-related EWs, the AA-based models achieved better performance on NA seeds, with R2v-2 value increasing from 0.696 to 0.720 for Lvsechaoren and from 0.668 to 0.727 for Zhongtian 300. In summary, coupling HSI, LC-MS/MS and machine learning was shown as an appropriate approach for non-destructive monitoring and predicting the vigour of stored sweetcorn seeds.

Analytical fast pyrolysis of P. Juliflora: A thermal and catalytic study

Thermal and catalytic fast pyrolysis of Prosopis juliflora (P.juliflora), fractions namely wood, seed pods, leaves and their mixtures (wood: seeds: leaves at 80:10:10, and seeds: leaves at 50:50) were investigated. Fast pyrolysis tests were performed in a py-GC/MS to study the product distribution at 450, 500 and 550 °C. Further catalytic tests at 500 °C, used HZSM-5, 1 wt% Ni-HZSM-5 and 5 wt% Ni-HZSM-5, and the wood fraction as feedstock. For all the non-catalytic thermal tests, significant proportions of acids, ketones, aldehydes, sugars, alcohols, phenols, nitrogenous compounds (NITs) and other oxygenates were observed. Out of the three Prosopis fractions studied, the wood at 500 °C yielded the highest amount of ketones, aldehydes and phenolics (78.67%), whilst the mixture (wood: seeds: leaves at 80:10:10), yielded 83.04%. This suggests that Prosopis feedstock can be processed as a mixture thus eliminating the need for pre-separation. The catalytic tests were completed at 500 °C with catalyst: biomass ratios (C/B) of 3:1, 6:1 and 9:1. The use of zeolite-based catalysts, improved the product distribution by forming aromatic hydrocarbons (monocyclic) and polycyclic aromatic hydrocarbons (PAHs) thus reducing the proportion of oxygenates detected in the thermal tests. The addition of nickel to the zeolite catalyst (9:1 C/B ratio; 5 wt% Ni-HZSM-5), resulted in aromatics and polyaromatic hydrocarbons (PAHs) yields of 60.28% and 27.50%, respectively. Overall, the tests using Ni-loaded zeolites showed selectivity towards aromatics, as higher proportions were obtained when compared to PAHs. Our results correlated the influence of specific components in the individual fractions of Prosopis (wood, seeds, and leaves) on the pyrolysis products. We established the potential of using an invasive plant to yield aromatics, which are main components for biofuels production, thus proposing a sustainable pathway to manage its spread and to yield a high-value product.

A comparative study on flavor trapping techniques from the viewpoint of odorants of hot-pressed rapeseed oil.

Rapeseed oil, as one of the three major vegetable oils in the world, its matrix effect makes the decoding flavor a challenge. Solid-phase microextraction (SPME), SPME-Arrow, headspace stir bar sorptive extraction (HSSE), direct thermal desorption (DTD), and solvent-assisted flavor evaporation (SAFE) were compared based on the odorants in hot-pressed rapeseed oil. Besides, methodological validation for 31 aroma standards was conducted to compare reliability and robustness of these approaches. DTD showed the largest proportion of acids, while the other techniques extracted a majority of nitriles. The highest number of odorants was detected by SAFE (31), followed by HSSE (30), SPME-Arrow (30), SPME (24), and DTD (14). SPME-Arrow showed the best performance in linearity, recovery, and reproducibility followed by SPME, HSSE, DTD, and SAFE. Results reveal the advantages and limitations of diverse methodologies and provide valuable insights for the selection of extraction methods in an oil matrix and flavor decoding.

Micellar Effect on the Oxidation of Anisaldehyde by Quinolinium Dichromate in Aqueous Acidic Media: A Kinetic Study

Aims: Oxidation of p-anisaldehyde by Quinolinium dichromate (QDC) in the aqueous acetic acid medium in the presence of sulphuric acid using surfactants. Background: The oxidation studies of anisaldehyde is very important as the oxidized products are used as a synthetic intermediate for the preparation of a variety of drugs. Quinolinium dichromate (QDC) has emerged as a very useful and versatile oxidant. Micellar medium enhances the reaction rate. Objective: 1. To study the kinetics of the reaction, which includes the determination of order, rate, and activation parameters. 2. Spectral characterization of QDC by NMR and the kinetic study of the reaction mechanism is done through UV – A visible spectrophotometer. 3. Solvent effect for the oxidation of anisaldehyde by QDC. 4. Determination of critical micelle concentration (CMC) of used surfactants (CTAB and SDS). Methods: The reactions were followed at constant temperature and were followed by monitoring the UV – Visible spectrophotometer (Double Beam – 2203) in a quartz cuvette of 1 cm path length by following the absorbance decay of Cr (VI) at 440 nm. Result: KINETIC RESULTS: 1. The reaction follows first-order dependence on panisaldehyde and QDC. 2. The reaction is found to be acid-catalysed. A plot of log [k] versus log [H+] was found to be a straight line with a slope of 1.07. EFFECT OF SOLVENT: The rate of reaction increases with the increase in acetic acid proportion in the medium, which suggests that the reactions were of the ion–dipole type. MICELLAR EFFECT: 1. Experimental results demonstrated that anionic surfactant SDS catalysed and accelerated the study more effectively than CTAB, which is a cationic surfactant, and the rate of reaction increases with an increase in the concentration of the SDS while in the case of CTAB, the rate decreases with an increase in its concentration. 2. CMC values of CTAB and SDS were 3.9 mM and 8.2 mM, respectively. Conclusion: The value of negative ΔS (entropy of activation) and positive ΔH (enthalpy of activation) suggests the formation of more ordered activated complexes, and the transition state is highly solvated. SPECTROSCOPIC ANALYSIS 1.NMR characterisation of synthesised QDC shows a resemblance with pure QDC. 2. Effect of oxidant QDC, panisaldehyde and acid was studied by considering the spectra of the reaction mixture and varying their concentration.

The Darker the Better: Identification of Chemotype Profile in Soroses of Local and Introduced Mulberry Varieties with Respect to the Colour Type.

Mulberries are the "essence of the past", the so-called Proust effect, for the inhabitants of the sericultural regions who enthusiastically remember feeding silkworms with mulberry leaves and picking the different coloured fruits that were their favourite sweets in childhood. To determine the chemistry behind the colour and taste of mulberry soroses, the main metabolites of the local and introduced varieties were studied. The soroses were classified into five different colour types and the size parameters were determined. The main sugars identified were glucose and fructose, while the predominant organic acids were citric and malic acids, which were highest in the darker varieties, and fumaric and tartaric acids, which were highest in the lighter varieties. A total of 42 phenolic compounds were identified. The predominant phenolic acid was chlorogenic acid, followed by other caffeoylquinic acids and coumaroylquinic acids. The predominant anthocyanins were cyanidin-3-glucoside and cyanidin-3-rutinoside. According to PCA analysis, the colour types showed a clear chemotype character. The sweet taste of the yellowish-white soroses was defined by 49% fructose, followed by 45% glucose and 6% organic acids. The sour character of the black genotypes was characterised by a lower sugar and higher (11%) organic acid content. The colour- and species-dependent effect was observed in the proportion of caffeoylquinic acids and quercetin glycosides, which decreased with increasing colour intensity from 60% of the total to 7%, and from 17% to 1%, respectively. An upward trend was observed for flavanols (5% to 29%) and anthocyanins, which accounted for 62% of the total phenolics in black varieties. This article gives an insight into the metabolite composition of mulberry soroses as the sweets of choice between light and sweet and dark and sour.

Unveiling Apple Diversity: The Quality of Juice Produced from Old vs. Commercial Apple Cultivars.

This research is focused on comparing the compositions of juice produced from old and commercially grown apple cultivars. We examined factors such as pH, total acids, soluble dry matter, polyphenol profile, and antioxidant activity, which impact the attributes, safety, shelf life, and nutritional value of the juice. Our analysis revealed differences between these two groups of cultivars. For instance, pH values ranged from 3.04 (in 'Bobovec') to 3.69 (in 'Fuji'). The proportions of acids varied from 0.07 g/100 mL (in 'Fuji') to 0.19 g/100 mL (in 'Wagener'). Soluble dry matter content ranged from 14.10% (in 'Fuji') to 18.50% (in 'Kraljevčica'). We also observed variations in sugar content and composition among cultivars; for example, sucrose levels varied from 16.11 g/L ('Fuji') to 39.36 g/L ('Golden Delicious). Glucose levels ranged from 4.95 g/L ('Jonagold') to 19.18 g/L ('Fuji'), while fructose levels spanned from 50.78 g/L ('Austrougarka') to 427.97 g/L ('Ilzer Rosenapfel'). Furthermore, old apple cultivars exhibited higher concentrations of phenols and flavonoids compared to commercial ones; we also noted significant variations in flavonol levels among different cultivars. The 'Wagener' and 'Božićnica' apple varieties had levels of myricetin measuring 0.53 and 0.52 µg/mL, respectively. On the other hand, 'Bobovec' stood out for its content of procyanidin B2 with a concentration of 422.61 µg/mL. When examining non-flavonoid compounds, it was found that old apple cultivars had higher concentrations of gallic acid, trans-ferulic acid, and chlorogenic acid. However, commercial cultivars showed dominance in caffeic and p-coumaric. Comparisons of antioxidant capacity using DPPH and ABTS assays clearly demonstrated the superiority of old apple cultivars. Overall, this study highlights the importance of utilizing apple cultivars for juice production. Their distinct compositions and higher antioxidant capacities contribute to potential health benefits. Preserving these cultivars for enhanced juice quality and nutritional value is encouraged. Further research could explore cultivation practices' impact on composition and health benefits.

Regulatory mechanisms and cell membrane properties of Candida glycerinogenes differ under 2-phenylethanol addition or fermentation conditions.

The biosynthesis of 2-phenylethanol (2-PE) at high yields and titers is often limited by its toxicity. In this study, we describe the molecular mechanisms of 2-PE tolerance in the multi-stress tolerant industrial yeast, Candida glycerinogenes. They were different under 2-PE addition or fermentation conditions. After extracellular addition of 2-PE, C. glycerinogenes cells became rounder and bigger, which reduced specific surface area. However, during 2-PE fermentation C. glycerinogenes cells were smaller, which increased specific surface area. Other differences in the tolerance mechanisms were studied by analyzing the composition and molecular parameters of the cell membrane. Extracellular 2-PE stress resulted in down-regulation of transcriptional expression of unsaturated fatty acid synthesis genes. This raised the proportion of saturated fatty acids in the cell membrane, which increased rigidity of the cell membrane and reduced 2-PE entry to the cell. However, intracellular 2-PE stress resulted in up-regulation of transcriptional expression of unsaturated fatty acid synthesis genes, and increased the proportion of unsaturated fatty acids in the cell membrane; this in turn enhanced flexibility of the cell membrane which accelerated efflux of 2-PE. These contrasting mechanisms are mediated by transcriptional factors Hog1 and Swi5. Under 2-PE addition, C. glycerinogenes activated Hog1 and repressed Swi5 to upregulate erg5 and erg4 expression, which increased cell membrane rigidity and resisted 2-PE import. During 2-PE fermentation, C. glycerinogenes activated Hog1 and repressed Swi5 to upregulate 2-PE transporter proteins cdr1 and Acyl-CoA desaturase 1 ole1 to increase 2-PE export, thus reducing 2-PE intracellular toxicity. The results provide new insights into 2-PE tolerance mechanisms at the cell membrane level and suggest a novel strategy to improve 2-PE production by engineering anti-stress genes.

Gac (Momordica cochinchinensis Spreng.) oil supplementation mitigates cognitive decline in AlCl3-induced rats through the regulation of Alzheimer's disease markers and autophagy via gut-brain communication

Previous studies showed that oleic acid-rich camellia oil (Camellia oleifera Abel., CO) alleviates the cognitive impairment symptoms of Alzheimer's disease (AD). Gac oil (Momordica cochinchinensis Spreng., GO) is rich in β-carotene, lycopene, and oleic acid; no study has explored the effects of GO on AD. Accordingly, this study examined the effects of GO and CO on AD prevention in rats subjected to AlCl3 intragastric gavage. The results exhibited similar effects of GO, CO, and GO/CO supplementation on restraining AlCl3-induced brain RAGE/NF-κB signaling, proinflammatory cytokines, MDA, and AD markers by upregulating anti-inflammatory cytokines, antioxidative enzymes, and autophagy, which subsequently enhanced the clearance of Aβ1-42 and memory capacity. Gut microbiota composition increased the proportions of short-chain fatty acids (SCFAs)-producing [Eubacterium]_coprostanoligenes_group and Lactobacillus_johnsonii in the oil intake groups, which were positively correlated with anti-inflammatory, autophagy, and dementia mitigation. This compelling evidence implies that consuming GO and CO is a strategy for AD prevention.

Optimization and Characterization of Lupin Protein Isolate Obtained Using Alkaline Solubilization-Isoelectric Precipitation.

The trend in today's society is to increase the intake of vegetable protein instead of animal protein. Therefore, there is a concern to find new sources of alternative protein. In this sense, legumes are the main protein source of vegetable origin. Of all of them, lupins are the ones with higher protein content, although they are currently undervalued as an alternative for human consumption. In this sense, it is vital to characterize and obtain protein isolates from this legume, which satisfies the growing demand. Therefore, in the present work, the procedure for obtaining a lupin (Lupinus luteus) protein isolate (LPI), based on basic solubilization followed by isoelectric precipitation, has been optimized and validated. The optimized LPI, as well as the lupin flour, were subsequently characterized. The chemical composition, physicochemical, as well as the technofunctional properties of the LPI were analyzed. The results show that the proposed procedure had a high yield (23.19 g LPI/100 g flour) and allowed to obtain high-purity protein isolates (87.7 g protein/100 g LPI). The amino acid composition and the chemical scores show high proportions of essential amino acids, being protein deficient only in methionine and valine. Therefore, it can be affirmed that it is a high-quality protein that meets the requirements proposed by the FAO. Regarding the lipid fraction, it is mainly composed of unsaturated fatty acids (C18:1n-9 and C18:2n-6), which is also advisable in order to follow a healthy diet. Finally, LPI showed interesting technofunctional properties (foaming, gelling, emulsifying, water and oil absorption, and solubility), which makes it especially attractive for use in the food industry.

Calcium peroxide mediated sustainable microalgal-bacterial consortium system: Role and significance of configured anaerobic fermentation

Microalgal-bacterial consortium (MBC) is an effective way to meet increasingly stringent standards in wastewater treatment, with advantages in nutrient removal, resource recovery, and energy conservation. The efficient and stable operation of the MBC sewage treatment system is generally limited by the insufficient and unstable carbon source in the influent. In this study, a calcium peroxide-mediated anaerobic fermenter was configured to transfer the MBC sludge into the preferred carbon source, short-chain fatty acids (SCFAs) in-situ, to alleviate the limitations. Experimental results showed that after 4-day 0.15 g/g VS calcium peroxide mediated anaerobic fermentation, the production of SCFAs and the proportion of acetic acid reached 514.8 mg COD/g VS and 59 %, respectively. Scanning electron microscopy, COD mass balance analysis, and lactate dehydrogenase assays jointly showed that calcium peroxide effectively promoted the breakdown of MBC sludge cells, which led to the release of large amounts of organic matter and could be attributed to the released OH–, ·OH and ·O2– from calcium peroxide, thereby providing more bioavailable substrates for SCFAs production. Microbial community analysis indicated that the anaerobes associated with hydrolysis and degradation of refractory organic matters were enriched in the mediated fermenter and had positive correlation with SCFAs production. Using such fermentation liquid as an additional carbon source for influent sewage, the MBC process performance was significantly promoted, with phosphorus and COD removal and sludge settleability reaching 84.7 %, 96.1 %, and 33 %, respectively. Configuring calcium peroxide-mediated anaerobic fermentation may thus become a sustainable strategy to strengthen the MBC sewage treatment system, thus providing new ideas for wastewater treatment to reduce inputs and improve performance.

Unlocking the potential of microalgae cultivated on wastewater combined with salinity stress to improve biodiesel production

Microalgae have the potential as a source of biofuels due to their high biomass productivity and ability to grow in a wide range of conditions, including wastewater. This study investigated cultivating two microalgae species, Oocystis pusilla and Chlorococcus infusionum, in wastewater for biodiesel production. Compared to Kühl medium, KC medium resulted in a significant fold increase in cellular dry weight production for both O. pusilla and C. infusionum, with an increase of 1.66 and 1.39, respectively. A concentration of 100% wastewater resulted in the highest growth for O. pusilla, with an increase in biomass and lipid content compared to the KC medium. C. infusionum could not survive in these conditions. For further increase in biomass and lipid yield of O. pusilla, different total dissolved solids (TDS) levels were used. Maximum biomass and lipid productivities were achieved at 3000 ppm TDS, resulting in a 28% increase in biomass (2.50 g/L) and a 158% increase in lipid yield (536.88 mg/g) compared to KC medium. The fatty acid profile of O. pusilla cultivated on aerated wastewater at 3000 ppm TDS showed a high proportion of desirable saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) for biodiesel production. Cultivating microalgae in wastewater for biodiesel production can be cost-effective, especially for microalgae adapted to harsh conditions. It could be concluded that O. pusilla is a promising candidate for biodiesel production using wastewater as a growth medium, as it has high biomass productivity and lipid yield, and its fatty acid profile meets the standard values of American and European biodiesel standards. This approach offers a sustainable and environmentally friendly solution for producing biofuels while reducing the environmental impact of wastewater disposal.

Effect of pomegranate seed oil on egg production, egg quality and yolk fatty acid deposition in laying hen.

Pomegranate seed oil (PSO) contains punicic acid as well as conjugated linolenic acid isomers, including α-eleostearic and catalpic acids, along with phytosterols, especially β-sitosterol, campesterol and stigmasterol, with lipotropic impact and egg fortifying effect in laying hens. The present experiment was designed to examine the effects of PSO on egg production, egg quality, blood lipids and yolk fatty acid deposition in laying hens. A total of 360 Hy-line laying hens (w-80), at 25 weeks of age, were randomly allotted to five dietary treatments in a completely randomized design during a 10-week period. Experimental treatments consisted of a basal diet or supplementation of 1, 2, 3 and 4gPSO/kg to basal diet. Performance indicators and fatty acid composition of egg yolk were evaluated during different experimental periods. Blood lipid attributes were evaluated at the end of the experiment. Dietary supplementation of 4gPSO/kg feed increased daily feed intake and egg production rate of laying hens (p<0.05). There was not any significant influence of experimental treatments on egg quality, whereas an increasing trend observed in egg yolk colour of hens received dietary graded levels of PSO. Dietary supplemental 4g/kgPSO increased the proportion of yolk poly-unsaturated fatty acid (PUFA) concentration (p<0.05). Furthermore, the PUFA to saturated fatty acid ratio increased after dietary supplementation of 1 or 4g/kgPSO (p<0.05). Serum concentration of cholesterol, triacylglycerol and low-density lipoprotein decreased in response to the supplementation of more than 3gPSO/kg in the feed (p<0.05). In conclusion, dietary supplementation with 4g/kgPSO improved production rate and decreased blood lipids in laying hens. Moreover, dietary supplemental PSO modified yolk fatty acid deposition without detrimental effects on the egg quality.

Study of the effect of germination on the chemical and nutritional properties of maize seeds

The research aimed to study the effect of the germination process on the chemical composition and content of phenolic compounds, phytic acid, mineral elements and amino acids of locally grown maize. The results of the chemical composition of the non-germinated maize showed that the content of protein, fat, ash, moisture, fiber, and carbohydrates were (7.75 - 10.271 - 1.46 - 6.79 -3.173 -70.886) respectively, while the results of germinated maize were from protein, fat, ash, fiber, carbohydrates (9.13- 9.167 -1.27- 5.93- 4.822- 69.861) respectively. As for the number of phenolic compounds, it increased after germination, as it reached germinated yellow maize compared to non-germinated maize (159 mg/gm-145 mg/gm) respectively, in addition to germination, it reduced the amount of phytic acid in germinated maize compared to non- germinated maize, which amounted to (2.8 mg/100gm). -48.9 mg/100 g) respectively. The percentage of mineral elements, iron, phosphorous, magnesium, potassium, zinc, and calcium for germinated maize reached (0.2883-3.87 -0.139-0.078 - 7.76-23.4), respectively. As for non-germinated maize, the percentage of iron, phosphorous, magnesium, potassium, zinc, and calcium (0.2811-3.43 -0.142-0.086-17.5-21.4) respectively. The effect of germination on the proportion of amino acids: the results showed that germination led to an improvement in the proportion of some essential and non-essential amino acids. Keywords: yellow corn, germination, amino acids, phytic acid

Biochemical Responses to the Long-Term Impact of Copper Sulfate (CuSO4) in Tobacco Plants.

Metabolic changes under stress are often studied in short-term experiments, revealing rapid responses in gene expression, enzyme activity, and the amount of antioxidants. In a long-term experiment, it is possible to identify adaptive changes in both primary and secondary metabolism. In this study, we characterized the physiological state of tobacco plants and assessed the amount and spectrum of phenolic compounds and the lignification of axial organs under excess copper stress in a long-term experiment (40 days). Plants were treated with 100 and 300 μM CuSO4, as well as a control (Knop solution). Copper accumulation, the size and anatomical structure of organs, stress markers, and the activity of antioxidant enzymes were studied. Lignin content was determined with the cysteine-assisted sulfuric method (CASA), and the metabolite profile and phenolic spectrum were determined with UHPLC-MS and thin-layer chromatography (TLC). Cu2+ mainly accumulated in the roots and, to a lesser extent, in the shoots. Copper sulfate (100 μM) slightly stimulated stem and leaf growth. A higher concentration (300 μM) caused oxidative stress; H2O2 content, superoxide dismutase (SOD), and guaiacol peroxidase (GPOX) activity increased in roots, and malondialdehyde (MDA) increased in all organs. The deposition of lignin increased in the roots and stems compared with the control. The content of free phenolics, which could be used as substrates for lignification, declined. The proportions of ferulic, cinnamic, and p-coumaric acids in the hydrolysate of bound phenolics were higher, and they tended toward additional lignification. The metabolic profile changed in both roots and stems at both concentrations, and changed in leaves only at a concentration of 300 μM. Thus, changes in the phenolic spectrum and the enhanced lignification of cell walls in the metaxylem of axial (root and stem) organs in tobacco can be considered important metabolic responses to stress caused by excess CuSO4.

Failure of Cronobacter sakazakii to acquire direct and cross-protection against lethal stresses after exposure to sublethal ethanol

Abstract Cronobacter sakazakii may encounter subinhibitory concentrations of ethanol stress over its lifecycle. Bacterial tolerance to homologous or heterologous stress agents may be altered as a result of ethanol adaptive responses. Therefore, the tolerance of ethanol-exposed and control cells to subsequent lethal stresses was evaluated in the current work. It was discovered that sublethal ethanol exposure increased the susceptibility to lethal ethanol stress in C. sakazakii as determined by the Weibull model. Furthermore, sublethal ethanol concentration exposure in C. sakazakii did not lead to any cross-tolerance against other stressors such as benzalkonium chloride (120 mg/L), heat (55 °C), cold (4 °C), simulated gastric fluid (pH 3.0), osmotic stress (sorbitol, 0.75 g/mL), and desiccation stress. Analysis of zeta potential, scanning electron microscope, and surface-enhanced Raman spectroscopy spectra revealed that cellular injury and changes in cellular chemical composition may contribute to the reduced resistance of C. sakazakii after ethanol exposure. Furthermore, sublethal ethanol exposure resulted in an elevated proportion of unsaturated fatty acids (USFA), while reducing the proportion of saturated fatty acids (SFA) and the ratio of SFA to USFA. The developed inactivation models can serve as a valuable source of data to support quantitative microbial risk assessment. Moreover, a better understanding of the response of C. sakazakii to sublethal ethanol exposure may provide valuable insights into the prevention and control of C. sakazakii.

Adaptive laboratory evolution of a thermophile toward a reduced growth temperature optimum.

Thermophily is an ancient trait among microorganisms. The molecular principles to sustain high temperatures, however, are often described as adaptations, somewhat implying that they evolved from a non-thermophilic background and that thermophiles, i.e., organisms with growth temperature optima (TOPT) above 45°C, evolved from mesophilic organisms (TOPT 25-45°C). On the contrary, it has also been argued that LUCA, the last universal common ancestor of Bacteria and Archaea, may have been a thermophile, and mesophily is the derived trait. In this study, we took an experimental approach toward the evolution of a mesophile from a thermophile. We selected the acetogenic bacterium T. kivui (TOPT 66°C) since acetogenesis is considered ancient physiology and cultivated it at suboptimal low temperatures. We found that the lowest possible growth temperature (TMIN) under the chosen conditions was 39°C. The bacterium was subsequently subjected to adaptive laboratory evolution (ALE) by serial transfer at 45°C. Interestingly, after 67 transfers (approximately 180 generations), the adapted strain Adpt45_67 did not grow better at 45°C, but a shift in the TOPT to 60°C was observed. Growth at 45°C was accompanied by a change in the morphology as shorter, thicker cells were observed that partially occurred in chains. While the proportion of short-chain fatty acids increased at 50°C vs. 66°C in both strains, Adpt45_67 also showed a significantly increased proportion of plasmalogens. The genome analysis revealed 67 SNPs compared to the type strain, among these mutations in transcriptional regulators and in the cAMP binding protein. Ultimately, the molecular basis of the adaptation of T. kivui to a lower TOPT remains to be elucidated. The observed change in phenotype is the first experimental step toward the evolution of thermophiles growing at colder temperatures and toward a better understanding of the cold adaptation of thermophiles on early Earth.

The Non-Nutritional Factor Types, Mechanisms of Action and Passivation Methods in Food Processing of Kidney Bean (Phaseolus vulgaris L.): A Systematic Review.

Kidney beans (KBs), as a traditional edible legume, are an important food crop of high nutritional and economic value worldwide. KBs contain a full range of amino acids and a high proportion of essential amino acids, and are rich in carbohydrates as well as vitamins and minerals. However, KBs contain a variety of non-nutritional factors that impede the digestion and absorption of nutrients, disrupt normal metabolism and produce allergic reactions, which severely limit the exploitation of KBs and related products. Suppressing or removing the activity of non-nutritional factors through different processing methods can effectively improve the application value of KBs and expand the market prospect of their products. The aim of this review was to systematically summarize the main types of non-nutritional factors in KBs and their mechanisms of action, and to elucidate the effects of different food processing techniques on non-nutritional factors. The databases utilized for the research included Web of Science, PubMed, ScienceDirect and Scopus. We considered all original indexed studies written in English and published between 2012 and 2023. We also look forward to the future research direction of producing KB products with low non-nutritional factors, which will provide theoretical basis and foundation for the development of safer and healthier KB products.

Perbandingan Asam Fenolat dan Total Fenolik Kopi Arabika Bogor dari Pengolahan Pascapanen dan Tingkat Sangrai Berbeda

Coffee is rich in phenolic compounds, which can be evaluated by the total phenolic or specific individual phenolics. The composition and concentration of phenolics in coffee are affected by various factors, including postharvest and roasting. This study aimed to compare the ratio of phenolic acid (measured as chlorogenic acid) to total phenolic in Bogor arabica coffee, considering different postharvest treatments and roasting levels. The coffee samples were treated with different postharvest (dry, wet, and honey) and roasting processes (light and dark). Green coffee bean was used as a control. The roasting process involved heating the coffee at temperatures ranging from 147.9 to 178.8°C for light roasting, and 190.2 to 200°C for dark roasting (10 minutes each). The color of the coffee beans, concentration of phenolic acid in the coffee extract, and total phenolic in the coffee extract were analyzed using a colorimeter, HPLC, and spectro-photometer respectively. The results showed that roasting significantly intensified the dark color of Bogor arabica coffee. Among the phenolic acids, the 5-CQA isomer emerged as the most dominant and was also the most susceptible to degradation during roasting. As the roasting level increased, the concentration of phenolic acid consistently decreased. Interestingly, the total phenolic initially increased in light roasted coffee but decreased in dark roasted coffee. Green coffee beans exhibited the highest proportion of phenolic acid (83%), whereas dark roasted coffee had the lowest proportion (19%). Although light roasted coffee had the highest total phenolic, its phenolic acid concentration decreased significantly compared to green coffee beans.

Physiological and transcriptomic insights into sugar stress resistance in osmophilic yeast Zygosaccharomyces rouxii

The osmophilic yeast Zygosaccharomyces rouxii has attracted increasing attention for its ability to survive and grow in extremely high sugar environments. This trait determines its role in fermentation process and results in contamination in the food industry. However, the behavior of Z. rouxii in regulating cell metabolism to combat high sugar stress and the corresponding mechanism have not been completely elucidated. Here, the resistance strategies of Z. rouxii against high glucose stress were explored by physiological analysis at cell membrane level and transcriptomic analysis. Physiological analysis showed that under high glucose stress, colony transparency increased, cell volume decreased, which was accompanied by reduction in permeability and integrity of cell membrane and subsequent gradual recovering. Additionally, the proportion of ergosterol and unsaturated fatty acids in cell membrane significantly increased under high glucose stress. A comparison of transcriptome data showed that most of the obtained differentially expressed genes (DEGs) involved in ergosterol and linoleic acid synthesis pathways as well as cell wall integrity (CWI) and high osmolarity glycerol mitogen-activated protein kinase (HOG-MAPK) pathways, which was in line with the results of physiological data. Our results provided a theoretic basis to develop the process control for the production of high sugar foods.