Evaluation of Nitrite, Ethyl Carbamate, and Biogenic Amines in Four Types of Fermented Vegetables

Nitrite, ethyl carbamate, and biogenic amines in fermented vegetables are considered harmful compounds. In this study, the concentration of the nitrite, ethyl carbamate, and biogenic amines in four different varieties of fermented vegetables in China was determined. The results show that the nitrite concentration in the fermented cabbage was the highest, followed by fermented mustard, fermented bamboo, and fermented radish. Additionally, nitrite concentration in two fermented cabbage samples and one fermented mustard sample exceeded the maximum allowed residue limit (20 mg/kg) suggested by China’s National Food Safety Standards. However, only one fermented cabbage sample had a very low level of ethyl carbamate (<10 μg/kg). Otherwise, higher biogenic amines were found in the samples of fermented cabbage, fermented bamboo, and fermented mustard. Additionally, the concentration of biogenic amines in some samples exceeded the recommended limit. On the contrary, biogenic amines in fermented radish samples were relatively low. Therefore, the concentration of nitrite and biogenic amine should be closely monitored and controlled during the vegetable fermentation processes, especially for the fermentation processes of bamboo, cabbage, and mustard.

Simultaneous Determination of Droplet Size, pH Value and Concentration to Evaluate the Aging Behavior of Metalworking Fluids

Metalworking fluids (MWFs) are widely used to cool and lubricate metal workpieces during processing to reduce heat and friction. Extending a MWF’s service life is of importance from both economical and ecological points of view. Knowledge about the effects of processing conditions on the aging behavior and reliable analytical procedures are required to properly characterize the aging phenomena. While so far no quantitative estimations of ageing effects on MWFs have been described in the literature other than univariate ones based on single parameter measurements, in the present study we present a simple spectroscopy-based set-up for the simultaneous monitoring of three quality parameters of MWF and a mathematical model relating them to the most influential process factors relevant during use. For this purpose, the effects of MWF concentration, pH and nitrite concentration on the droplet size during aging were investigated by means of a response surface modelling approach. Systematically varied model MWF fluids were characterized using simultaneous measurements of absorption coefficients µa and effective scattering coefficients µ’s. Droplet size was determined via dynamic light scattering (DLS) measurements. Droplet size showed non-linear dependence on MWF concentration and pH, but the nitrite concentration had no significant effect. pH and MWF concentration showed a strong synergistic effect, which indicates that MWF aging is a rather complex process. The observed effects were similar for the DLS and the µ’s values, which shows the comparability of the methodologies. The correlations of the methods were R2c = 0.928 and R2P = 0.927, as calculated by a partial least squares regression (PLS-R) model. Furthermore, using µa, it was possible to generate a predictive PLS-R model for MWF concentration (R2c = 0.890, R2P = 0.924). Simultaneous determination of the pH based on the µ’s is possible with good accuracy (R²c = 0.803, R²P = 0.732). With prior knowledge of the MWF concentration using the µa-PLS-R model, the predictive capability of the µ’s-PLS-R model for pH was refined (10 wt%: R²c = 0.998, R²p = 0.997). This highlights the relevance of the combined measurement of µa and µ’s. Recognizing the synergistic nature of the effects of MWF concentration and pH on the droplet size is an important prerequisite for extending the service life of an MWF in the metalworking industry. The presented method can be applied as an in-process analytical tool that allows one to compensate for ageing effects during use of the MWF by taking appropriate corrective measures, such as pH correction or adjustment of concentration.

Nutrient Distribution in Eastern Indonesian Waters

Nutrients are needed for the growth of phytoplankton as a basic component in the marine food web. The concentration of nutrients in waters relates to primary productivity and it will influence fisheries stocks. So far, research on nutrients in the deep sea is rarely carried out in Indonesia. This study aims to determine water quality, horizontal and vertical distribution of nutrients in eastern Indonesian waters, which can be used as baseline data for deep-sea nutrients in Indonesia. The study was conducted from October 29 to November 15, 2017. Sampling was carried out in 20 stations with seven layers. Nutrient measurements were conducted based on Strickland and Parsons (1972). Our results showed that the concentrations of phosphate, nitrate, nitrite, ammonium, and silicate ranged from 0.000-0.060 mg/l, 0.001-0.321 mg/l, 0.000-0.009 mg/l, 0.004-0.024 mg/l and 0.085-1.090 mg/l, respectively. In general, the highest concentration of nutrients was found in Maluku Sea. The vertical distribution of nitrate, phosphate, and silicate shows that the increasing concentrations as increasing depth, except for nitrite and ammonium. The maximum nitrite concentration appears in the northern area, while the ammonium distribution has homogenous pattern.

Controls on nitrite oxidation in the upper Southern Ocean: insights from winter kinetics experiments in the Indian sector

Across the Southern Ocean in winter, nitrification is the dominant mixed-layer nitrogen cycle process, with some of the nitrate produced therefrom persisting to fuel productivity during the subsequent growing season, potentially weakening the spring/summer biological CO2 sink. To better understand the controls on Southern Ocean nitrification, we conducted nitrite oxidation kinetics experiments in surface waters across the western Indian sector in winter. While all experiments (seven in total) yielded a Michaelis-Menten relationship with substrate concentration, the nitrite oxidation rates only increased substantially once the nitrite concentration exceeded 115±2.3 to 245±18 nM, suggesting that nitrite oxidizing bacteria (NOB) require a minimum (i.e., "threshold") nitrite concentration to produce nitrate. The half-saturation constant ranged from 134±8 to 403±24 nM, indicating a relatively high affinity of Southern Ocean NOB for nitrite, in contrast to results from culture experiments. Despite the high affinity of NOB for nitrite, its concentration rarely declines below 150 nM in the Southern Ocean's mixed layer, regardless of season. In the upper mixed layer, we measured ammonium oxidation rates that were two- to seven-fold higher than the coincident rates of nitrite oxidation, indicating that nitrite oxidation is the rate-limiting step for nitrification in the winter Southern Ocean. The decoupling of ammonium and nitrite oxidation, combined with a possible nitrite concentration threshold for NOB, may explain the non-zero nitrite that persists throughout the Southern Ocean's mixed layer year-round. We hypothesize that the apparent threshold nitrite requirement of NOB indicates nitrite undersaturation of the heme-rich nitrite oxidoreductase enzyme, perhaps driven by the limited availability of iron in surface waters.

Metabolic programming in offspring of mice fed fructose during pregnancy and lactation

Fructose (C6H12O6), also known as levulose, is a hexose. Chronic consumption of fructose may be associated with increased intrahepatic fat concentration and the development of insulin resistance as well as an increase in the prevalence of nonalcoholic fatty liver disease and hyperlipidemia during pregnancy. Despite the existence of many studies regarding the consumption of fructose in pregnancy, its effects on fetuses have not yet been fully elucidated. Therefore, the objective of this study was to evaluate the genetic and biochemical effects in offspring (male and female) of female mice treated with fructose during pregnancy and lactation. Pairs of 60-day-old Swiss mice were used and divided into three groups; negative control and fructose, 10%/l and 20%/l doses of fructose groups. After offspring birth, the animals were divided into six groups: P1 and P2 (males and females), water; P3 and P4 (males and females) fructose 10%/l; and P5 and P6 (males and females) fructose 20%/l. At 30 days of age, the animals were euthanized for genetic and biochemical assessments. Female and male offspring from both dosage groups demonstrated genotoxicity (evaluated through comet assay) and oxidative stress (evaluated through nitrite concentration, sulfhydril content and superoxide dismutase activity) in peripheral and brain tissues. In addition, they showed nutritional and metabolic changes due to the increase in food consumption, hyperglycemia, hyperlipidemia, and metabolic syndrome. Therefore, it is suggested that high consumption of fructose by pregnant female is harmful to their offspring. Thus, it is important to carry out further studies and make pregnant women aware of excessive fructose consumption during this period.

Effect of the Dry-Cured Fermented Sausage “Salchichón” Processing with a Selected Lactobacillus sakei in Listeria monocytogenes and Microbial Population

In the present work, the effect of processing of dry-cured fermented sausage “salchichón” spiked with the selected Lactobacillus sakei 205 was challenge-tested with low and high levels of L. monocytogenes. The evolution of the natural microbial population throughout the “salchichón” ripening was also evaluated. For this, a total of 150 “salchichón” were elaborated and divided into six equal cases which were inoculated with different levels of L. monocytogenes, and L. sakei 205. Afterwards, sausages were ripened for 90 days according to a typical industrial process. Moisture content (%) and water activity (aw) decreased throughout the ripening up to values around 26% and 0.78, respectively. No differences for moisture content, aw, pH, NaCl and nitrite concentration were observed between the analyzed cases. Lactic acid bacteria counts in the L. sakei 205 inoculated cases were always higher than 6 log CFU g−1 during ripening. Enterobacteriaceae counts were reduced during ripening until non-detectable levels at the end of processing. Reductions in L. monocytogenes counts ranged from 1.6 to 2.2 log CFU g−1; therefore, the processing of “salchichón” itself did not allow the growth of this pathogen. Reduction in L. monocytogenes was significantly higher in the cases inoculated with L. sakei 205.

Correlation of Nitrite and Ammonia with Prevalence of Enterocytozoon hepatopenaei (EHP) in Shrimp (Litopenaeus vannamei) on Several Super-Intensive Ponds in East Java, Indonesia

Enterocytozoon hepatopenaei (EHP), a microsporidia parasite known to hinder shrimp growth by infecting its hepatopancreas, is recently an emerging infection for Litopenaeus vannamei farms in Indonesia. The present study was conducted to investigate the relationship between nitrite and ammonia concentration with EHP infection in the super-intensive ponds. Shrimps and water samples were collected from six ponds in aquaculture super-intensive ponds with a stocking density of 5,000 shrimps in each pond which is located in Pasuruan, Lamongan, and Tuban Regency, Indonesia. The water sample was taken to the laboratory for the measurement of ammonia and nitrite. The samples of ammonia and nitrite were detected by spectrophotometer, and the PCR was used to detect 18S rRNA of EHP. The PCR analysis that showed two positive samples of L. vannamei, from the ponds with a high concentration of ammonia and nitrite, were infected by EHP. The statistical analysis showed a significant correlation between ammonia and nitrite with the prevalence of EHP infections, where the Pearson correlation (r) was 0.980 and 0.943, respectively. There was a high prevalence of EHP infection with the increase in nitrite concentration and ammonia in pond four and pond six. The concentration of over 1mg/l of ammonia and nitrite could influence EHP infection prevalence in the shrimp farms. Highlight ResearchAmmonia and nitrite concentration influence the prevalence of Enterocytozoon hepatopenaei infection in Super intensive ponds.The estimated prevalence of Enterocytozoon hepatopenaei was 16.7%.PCR amplification analysis was used to detect the 18S ss-rRNA of Enterocytozoon hepatopenaei and 510-bp was obtained.