The impact of temperature-controlled smoldering smoking on polycyclic aromatic hydrocarbons and heterocyclic amines contents in Frankfurter-type sausages.

The impact of temperature-controlled smoldering smoking conditions on the accumulations of polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HAs) in Frankfurter-type sausages was investigated. Depending on the temperature, smoking can be divided into two phases: an unstable pyrolysis stage (≈ 200 s) and a stable pyrolysis stage (>200 s), which had different effects on hazardous substances contents. The unstable pyrolysis stage, which contributed 66.9 âˆ¼ 89.6% of PAH accumulations by comparing with sausages smoked for 15 min, has significant impact on high PAH residues. By contrast, the contents of HAs showed steady increase trends with smoking time. Few types of free-HAs with low concentrations (3.05 âˆ¼ 22.9 ng/g DW), but more types of bound-HAs with much higher levels (10.8 âˆ¼ 396 ng/g DW) were found. In addition, the formation of some HAs followed the first-order reaction model. However, the detailed formation mechanisms of PAHs and HAs under temperature-controlled smoldering smoking conditions remain to be studied.

Meat quality and flavor evaluation of Nanjing water boiled salted duck (NWSD) produced by different Muscovy duck (Cairina moschata) ingredients.

Reports on meat quality and flavor evaluation of Nanjing water boiled salted duck (NWSD) produced by different Muscovy duck (Cairina moschata) ingredients are limited. To select a suitable Muscovy duck ingredient for the NWSD processing, six kinds of NWSD products were produced using female (65, 70, and 75 days) and male (75, 80, and 85 days) Muscovy duck ingredients. The meat quality, volatile organic compounds (VOCs), smell and taste were investigated by using colorimeter, texture analyzer, headspace-gas chromatography-ion mobility spectroscopy (HS-GC-IMS), electronic nose (E-nose), electronic tongue (E-tongue), etc. Results exhibited that 32 iconic VOCs were obtained by using partial least squares discrimination analysis (PLS-DA), principal component analysis (PCA), and variable importance projection (VIP) methods. 80-day-old male Muscovy duck showed moderate moisture and protein content, good meat texture and bright color, diverse iconic VOCs and clear differentiation, making it the preferred ingredient for NWSD processing.

Changes in bacterial communities and the volatilome of braised chicken with different packaging stored at 4 ℃.

The objective of this study was to investigate the effect of air packaging (AP), modified atmosphere packaging (MAP, 40% CO2/60 % N2) and vacuum packaging (VP) on the dynamic changes of bacterial communities and volatile organic compounds (VOCs) in braised chicken stored at 4 ℃. Physicochemical characteristics and microbiological parameters were also measured. Results showed that MAP and VP groups obtained a slower growth rate of total viable count (TVC) and better sensory scores than AP groups. High throughput sequencing showed that Proteobacteria and Firmicutes were the dominant phyla in braised chicken samples. Additionally, different packaging conditions had significant effects on the succession of bacteria at the genus level. At the beginning of storage, Sphingomonas, Bradyrhizobium, Acinetobacter, Psychrobacter and Phyllobacterium dominated the microflora of braised chicken. However, on day 28, Staphylococcus and Serratia became the predominant genera in MAP and VP samples, respectively. Furthermore, thirty-two VOCs were detected in all braised chicken samples. Following the results of Spearman's correlation analysis, positive correlations were observed between Staphylococcus and all the compounds except for heptanoic acid. These results might provide valuable information regarding the quality improvement of braised chicken during refrigerated storage.

[Occurrence of Antibiotics and Antibiotic Resistance Genes in Representative Drinking Water Resources in Jiangsu Province].

Emerging contaminants including antibiotics and antibiotic resistance genes (ARGs) have been frequently detected in drinking water resources. In this study, the occurrence of antibiotics and ARGs in various environmental matrices in representative drinking water sources in Jiangsu Province and their influencing factors were explored. Five representative drinking water sources in northern, central, and southern Jiangsu were selected. Water, surface sediment, and epilithic biofilm samples were harvested near the water intakes of each water resource in December 2018 and June 2019. The concentrations and abundances of ten antibiotics, one integrase gene intl1, and seven common ARGs were measured. The results suggest that the concentrations of the target antibiotics and ARGs are relatively low compared to previously reported data in China and elsewhere in the world. The target antibiotics were detected in all of the water sources. The concentrations of sulfonamides in the water, surface sediment, and epilithic biofilm ranged from not found (NF) to 37.4 ng·L-1, NF to 47.3 ng·g-1, and NF to 3759.1 ng·g-1, respectively; the concentrations of quinolones in three matrices were NF-5.3 ng·L-1, 0.4-32.5 ng·g-1, and NF-4220.9 ng·g-1, respectively. The detection rates of the ARGs including sul 1, sul2, tetW, and tetQ were 100%, among which the sulfonamides sul1 and sul2 showed the highest abundance. The absolute abundances of sul1 in the three matrices were 2.48×106 copies·L-1, 3.54×107 copies·g-1, and 1.44×109 copies·g-1, respectively. The abundances of ARGs in the sediments and epilithic biofilms were comparable, and were much higher than in the water body. The phyla Bacteroidetes, Proteobacteris, Firmicutes, Verrucobacteria, and Actinomycetes have proven potential hosts for ARGs and might play an important role in the transmission and diffusion of resistance genes. This study offers baseline information on the presence of antibiotics and ARGs in the drinking water sources of Jiangsu Province, providing a significant theoretical basis for ARGs pollution control and safety guidelines for drinking water resources.

Content of free and protein-binding Nε-carboxymethyllysine and Nε-carboxyethyllysine in different parts of braised chicken.

In order to illustrate the levels of advanced glycation end products (AGEs) in Chinese traditional braised chicken, the distribution of free and protein-binding Nε-carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL) in four parts of processed chicken including chest (X), leg (T), skin (P), and the mixed whole body (M) was investigated. Our results showed that the content of free CML was 1,186.63-1,795.43 ng/g meat and protein-binding CML was 11,693.91-16,122.90 ng/g meat. Differently, the content of free CEL was 24.81-41.62 ng/g meat and protein-binding CEL was 270.11-385.49 ng/g meat. It was found that the total contents of CML were 31.5-56.8 folds higher than those of CEL. Protein-binding AGEs (CML + CEL) were 6.6-9.9 times higher than those of free AGEs (CML + CEL). Pearson's correlation of AGEs and oxidation in four parts of braised chicken were also investigated, and the results showed that oxidation had a significant effect on levels of CEL; especially, the protein carbonyl was negatively correlated with free CEL (p < .05). TBARs value was significantly positively correlated with protein-binding and total CEL (p < .01). In conclusion, our findings are important for better understanding of the AGEs formation in braised meat.

Effects of Cooking Methods and Tea Marinades on the Formation of Heterocyclic Amines and Benzo[a]pyrene in Grilled Drumsticks.

ABSTRACT: The effects of different grilling methods and tea marinades on the formation of heterocyclic amines (HCAs) and benzo[a]pyrene (BaP) in grilled chicken drumsticks were investigated. This study showed that both the grilling method and type of charcoal used in charcoal grilling had a significant effect on the formation of HCAs and BaP. The total content of HCAs and BaP detected in drumsticks was the lowest under electric roasting, at 7.25 and 0.04 ng/g, respectively; thus, the electric grill can be used as an alternative grilling method to meet consumer demands for safety. The free radical scavenging ability of tea infusion was significantly higher than that of spice infusion. The white tea marinade significantly increased radical scavenging activity and prevented formation of HCAs and BaP more than the green tea marinade; thus, tea marinade can be applied to flavoring as a pretreatment to preserve the quality of meat and to decrease the generation of HCAs and BaP during cooking.

Heterocyclic amines in braised chicken may mainly infiltrate from reused marinade during braising, instead of thermic generation.

BACKGROUND: Sauce braised meat products are popular in Asia, although their complicated processing may lead to potential safety risks. Especially, how hazardous compounds are formed during their preparation is still unclear. In the present study, braised chicken breasts, which are a typical Chinese sauce braised meat product, were used to investigate the formation of heterocyclic amines (HCAs) during heat treatment. RESULTS: Precursor content (creatine and reducing sugar), HCA level and temperature were measured in different parts of the chicken breast at each processing stage. The results obtained showed that the increasing trends of total HCA content in different parts of chicken breast were not the same. Only total HCA content in the skin (4.93 ± 0.80 ng g-1 ) increased significantly after deep-frying. During braising, total HCA level in the skin was high (12.1-14.3 ng g-1 ) and relatively stable. However, total HCA content in pectoralis major muscle (3.90-7.40 ng g-1 ) and pectoralis minor muscle (1.44-5.31 ng g-1 ) was much lower than in the skin, and increased steadily with braising time. CONCLUSION: Braising is the main factor which affects HCA level in braised chicken. Combining the results of temperature and precursor content, a possible explanation for the large amount of HCAs in braised chicken is the gradual infiltration from reused marinade, instead of thermic generation. © 2019 Society of Chemical Industry.

Formation of Nϵ-Carboxymethyllysine and Nϵ-Carboxyethyllysine in Prepared Chicken Breast by Pan Frying.

The objective of this work was to investigate the effects of pan frying on the formation of two typical advanced glycation end products (AGEs) named Nϵ-carboxymethyllysine (CML) and Nϵ-carboxyethyllysine (CEL) in prepared chicken breast. The marinated chicken breast was pan fried for 1 to 6 min, and then protein, fat, moisture, carbonyl, sulfhydryl, thiobarbituric acid reactive substances, chroma (a*, b*, L*), absorbance at 294 and 420 nm, and AGE (CEL) levels were measured once a minute. Pearson's correlation was determined and indicated that moisture was significantly negatively correlated with Maillard reaction and AGEs (P < 0.05), fat and protein contents were significantly positively correlated with AGEs (P < 0.05), and a* values were positively correlated with Maillard reaction and CEL (P < 0.05). Protein and lipid oxidation played an important role on the correlation of AGEs. In conclusion, Maillard reaction and oxidation reaction are two important factors affecting AGE formation.

Content, causes and analysis of heterocyclic amines in Chinese traditional braised chicken.

Braised chicken is a popular traditional chicken product in China with a special and complicated culinary method. However, there has been little research focused on the food safety problems caused by hazardous compounds in braised chicken. In this study, the contents of heterocyclic amines (HCAs) in representative braised chicken samples were determined. Total HCAs in braised chicken were relatively high (6.20-27.7 ng g-1), and aminoimidazoazaarenes (AIAs) took a large proportion (54.0-86.4%). 2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) was found in all samples with a high level (2.72-13.5 ng g-1), whilst 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was low (0.14-0.41 ng g-1). 9H-pyrido[3,4-b]indole (Norharman) and 1-methyl-9H-pyrido[3,4-b]indole (Harman) were main components in aminocarbolines (ACs). So the potential safety risk in braised chicken caused by high HCAs content should be paid attention. Principal component analysis (PCA) was used to analyse and visualise the differences of HCAs levels among braised chicken samples. The result indicated that the differences among these samples were significant, but there were no obvious similarities between samples produced in the same regions. Moreover, there were rare significant positive correlations between chemical components (including moisture, fat, protein, creatine and free amino acids) and hazardous compounds. Considering PCA and correlation analysis results, these parameters may play a major role in the HCAs levels in Chinese traditional braised chicken.

Design and Properties of an Immobilization Enzyme System for Inulin Conversion.

A commercial inulinase could convert inulin into fructose, which was optimized to be entrapped in the calcium alginate-gelatin beads with the immobilization yield of 86% for free inulinase activities. The optimum pH values and temperatures were 4.5 and 40 °C for the free enzyme and 5.0-5.5 and 45-50 °C for the immobilized enzyme. The kinetic parameters of V max and K m were 5.24 µmol/min and 57.6 mg/mL for the free inulinase and 4.32 µmol/min and 65.8 mg/mL for the immobilized inulinase, respectively. The immobilized enzyme retained 80% of its initial activities at 45 °C for 4 days, which could exhibit better thermal stability. The reuse of immobilized inulinase throughout the continuous batch operations was explored, which had better reusability of the immobilized biocatalyst. At the same time, the stability of immobilized enzyme in the continuous packed-bed bioreactor was estimated, which showed the better results and had its potential scale-up fructose production for inulin conversion.

Gαq-protein carboxyl terminus imitation polypeptide GCIP-27 attenuates proliferation of vascular smooth muscle cells and vascular remodeling in spontaneously hypertensive rats.

Gq-protein is located at the convergent point in signal transduction pathways leading to vascular remodeling. The carboxyl terminus of Gα-subunit plays a vital role in G-protein-receptor interaction. The present study was designed to explore the effects of a synthetic Gαq carboxyl terminus imitation peptide, namely GCIP-27, on vascular smooth muscle cells (VSMC) in vitro and vascular remodeling in spontaneous hypertensive rats (SHR). Hyperplasia and hypertrophy of VSMC wre determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, [(3)H]-thymidine and [(3)H]-leucine incorporation, and [Ca(2+)](i) was measured with Fluo-3/AM staining. Systolic blood pressure (SBP), the ratio of media thickness to lumen diameter (MT/LD) of aorta, collagen content, and phospholipase C activity in aorta were measured in SHR. GCIP-27 (3-100 µg/l) significantly decreased proliferation activity, protein content, incorporation of [(3)H]-thymidine and [(3)H]-leucine, and [Ca(2+)](i) level in VSMC. SBP, MT/LD, collagen content, and phospholipase C activity in aorta of SHR were decreased significantly in GCIP-27 (7, 20, 60 µg/kg)-treated groups and losartan (6 mg/kg) group compared with vehicle group. In conclusion, GCIP-27 could inhibit vascular remodeling effectively in vitro and in vivo.

Inhibition of left ventricular remodelling in spontaneously hypertensive rats by G alpha q-protein carboxyl terminus imitation polypeptide GCIP-27 is not entirely dependent on blood pressure.

The G(q)-protein is located at the convergent point in the signal transduction pathway that leads to ventricular remodelling. In G-protein signalling pathways, the carboxyl terminus of the G(alpha)-subunit plays a vital role in G-protein-receptor interaction. The aim of the present study was to explore the effects of a synthetic G(alphaq) carboxyl terminus imitation peptide, namely GCIP-27, on left ventricular (LV) remodelling and blood pressure in spontaneous hypertensive rats (SHR). In the present study, 10, 30 or 90 microg/kg, i.p., GCIP-27 was administered for 8 weeks to SHR. In addition, another two groups of SHR were treated with either 6 mg/kg losartan or vehicle (saline). Wistar-Kyoto rats were used as controls. Systolic blood pressure (SBP) was measured using the standard tail-cuff method once every 2 weeks. At the end of the experiment, the LV mass index (LVMI) was evaluated. In addition, LV structure and function, collagen content, microstructure and ultrastructure were examined using echocardiography, the hydroxyproline assay, routine light microscopy and transmission electron microscopy, respectively. In the losartan- and GCIP-27 (10, 30 and 90 microg/kg)-treated groups, SBP was decreased significantly compared with that of the vehicle (saline) group. However, even at the highest concentration used, the hypotensive effect of GCIP-27 was weaker than that of losartan. For example, after 8 weeks treatment, SBP had decreased by 30.4% in the losartan-treated group compared with decreases of 10.5, 13.1 and 18.5% in the 10, 30 and 90 microg/kg GCIP-27-treated groups, respectively. Both GCIP-27 (10, 30 and 90 microg/kg) and losartan (6 mg/kg) significantly reduced LV posterior wall thickness, the thickness of the interventricular septum, collagen content and LVMI, with the effects of GCIP-27 at all three concentrations tested being greater than those of losartan. In conclusion, GCIP-27 effectively attenuates LV remodelling in SHR and the antiremodelling effect may not be dependent entirely on decreases in blood pressure.