Total Volatile Base Research Articles

A colorimetric total volatile base nitrogen-responsive film with antibacterial and leaching-resistant properties for accurate tracking fish quality

In this work, an antibacterial, safer, and intelligent film based on dye-loaded rice straw composite was designed for tracking fish freshness. Rice straw was treated with NaOH to graft cations for linking pH-sensitive pigment without separation. Higher concentrations of NaOH removed more hemicellulose, lignin, ash and fat-soluble compounds from rice straw than that of the lower NaOH concentration, improving accessibility to cellulose. NaOH at 10 g/dL changed some of the cellulose crystals from type I to type II. Bromothymol blue molecules (BTBMs) were connected on cationic particles via ionic bonds to obtain porous TVB-N-responsive granules, which were encapsulated in a carboxymethyl cellulose/κ-carrageenan composite to monitor fish freshness. The static attraction and repulsion on BTBMs from cationic rice straw and the anionic polysaccharide composite increased leaching-resistance with a release ratio of 1.76% in 76 g/dL ethanol solution. The smart film had a UVC resistance of 64.48%, a Staphylococcus aureus inhibition rate of 92%, and an optimum TVB-responsive performance. The film turned yellow, green or blue to indicate fish was very fresh, fresh, or close to spoilage, respectively. Our study provides information on the utilization of rice straw and a methodology for the large-scale preparation of smart films for evaluating fish freshness.

A multiple parameters fusion model based on hydrogen sulfide for accurately evaluating the freshness of lamb meat

SummaryHydrogen sulfide (H2S), as an important freshness indicator of meat, can effectively reflect the degree of spoilage. However, establishing a multiple parameters fusion model with temperature correction to fit the relationship between the H2S concentration and other freshness indicators is still a challenge. In this study, the M. longissimus thoracis et lumborum muscle (LTL) of lamb was stored in air packaging at 0 °C, 4 °C, 8 °C, 12 °C and 25 °C, respectively, to monitor the changes of gaseous H2S and other fresh indicators. The correlation analysis indicates that H2S concentration is highly consistent with lamb meat freshness. During the analysis, the well‐fitted Stirling models show high statistical relationships between H2S and total viable count (TVC)/total volatile base nitrogen (TVB‐N) values with the determination coefficients (R2) all exceeding 0.9000. Subsequently, the fusion freshness prediction models with the temperature corrections were successfully established by fusing the exponential models into the Stirling models. As verified, the fusion freshness prediction models based on H2S concentration can offer accurate predictions of the TVC and TVB‐N values of lamb meat at different temperatures with an R2 of 0.9352 and 0.8627, respectively. The proposed models might be used to accurately forecast and evaluate the freshness of meat in the process of storage.

Effect of rosemary (Rosmarinus officinalis) extract on the protection of the fishballs from knife fish (Chitala chitala) and striped catfish by-product (Pangasianodon hypophthalmus) against spoilage during frozen storage

The study aimed to investigate the effect of rosemary (Rosmarinus officinalis) extract on the quality changes of fishballs from knife fish (Chitala chitala) and striped catfish byproduct (Pangasianodon hypophthalmus) during frozen storage. Fishballs were supplemented with rosemary extracts at two concentrations of 13 mg/kg and 156 mg/kg. The control treatment was the sample without extract. The products were steamed, vacuum packed in PA bags and stored at a temperature from -18oC to -20oC. Sampling was done at 0, 30, 60, 90, 120, 150 and 180 days of storage period for analysis of pH, Total volatile base nitrogen (TVB-N), total viable bacteria count (TVC), pathogenic bacteria, sensory properties, peroxide value (PV), Thiobarbituric acid reactive substances (TBARs). Results showed that Escherichia coli and Salmonella spp. were absent in the fishballs, reflecting the safety of products for consumers. Adding rosemary extract at 156 mg/kg in fishballs displayed more effectiveness in inhibiting the formation of lipid oxidation and microbial growth when compared to the control sample during the frozen storage. Based on the results of physicochemical and sensory quality, the supplementation of rosemary extracts showed a significant promise for improving the quality of fishballs. Fishballs from knife fish and striped catfish by-products could be maintained their sensory properties and prolonged their shelf-life up to 180 days of frozen storage.

Antibacterial smart absorbent pad with Janus structure for meat preservation

In this work, an antibacterial smart absorbent pad with Janus structure was prepared to preserve and indicate the quality of meat. The pad had two layers, polyurethane (PU) nanofibers as the top hydrophobic layer and polyvinyl alcohol (PVA) nanofibers as the bottom absorbent layer. Polyhexamethylenebiguanide hydrochloride (PHMB) was added to the top layer as cationic antimicrobial agent because guanidine group could maintain its strong positive charge in alkaline environment, which keeps the antibacterial ability during meat spoilage that is a process of pH increasing. Besides, the juice of the meat can be absorbed to the bottom layer while the hydrophobic top layer in contact with meat remains dry, which can reduce the multiplication of bacteria. Furthermore, anthocyanin was added to the bottom layer as an indicator to detect spoilage of meat. The experiments show the new antibacterial indicator absorbent pad can effectively inhibit bacterial growth (less than 5 lg CFU/g after 8 days), prolong the shelf life of fresh meat (total volatile base nitrogen less than 20 mg/100 g) to 7 days when stored at 4 °C and indicate the deterioration of meat.

A colorimetric and fluorescent sensor for non-destructive screening of the freshness of shrimp and fish

The freshness of fish and shrimp is closely associated with food safety, hence it is a wide concern to develop a facile and effective method for fast, non-destructive and visual screening the freshness of fish and shrimp. Herein, we developed a chromogenic and fluorogenic sensor (RFCC) based on resorufin for sensing of biogenic amines including cadaverine and putrescine. RFCC underwent aminolysis with cadaverine or putrescine, displaying a remarkable fluorescence turn on response at 593 nm along with obvious color change from colorless to pink. RFCC was fabricated into test strips to sense cadaverine vapor, and the RGB value of test strips showed a good linear relationship with the concentration of cadaverine (0.5 – 8.2 × 103 ppm). The RFCC tag was used to in situ screen the freshness of fish and shrimp according to obvious fluorescence change, and satisfactory results were achieved. Furthermore, this test strip was validated by total volatile base nitrogen (TVBN), providing a simple, low cost and portable tool to screen the freshness of fish and shrimp for consumers and suppliers without expensive instrumentation.

Inactivation of Vibrio parahaemolyticus and retardation of quality loss in oyster (Crassostrea gigas) by ultrasound processing during storage

The health problems caused by foodborne pathogens of raw oysters have been widely concerned. Traditional heating methods tend to lead the loss of the original nutrients and flavors, in this study, the nonthermal ultrasound technology was applied to inactivate Vibrio parahaemolyticus on raw oysters, and the retardation effects on microbial growth and quality loss of oysters stored at 4 ℃ after ultrasonic treatment were also investigated. After treated by 7.5 W/mL ultrasound for 12.5 min, the Vibrio parahaemolyticus in oysters was reduced by 3.13 log CFU/g. By measuring total aerobic bacteria and total volatile base nitrogen, the growth trend after ultrasonic treatment was delayed compared with heat treatment, and the shelf life of oysters was prolonged. At the same time, ultrasonic treatment delayed the changes of color difference and lipid oxidation of oysters during cold storage. Texture analysis showed that ultrasonic treatment helped maintain the good textural structure of oysters. Histological section analysis also demonstrated that muscle fibers were still tightly packed after ultrasonic treatment. Low-field nuclear magnetic resonance (LF-NMR) illustrated that the water in the oysters was well maintained after ultrasonic treatment. In addition, gas chromatograph – ion mobility spectrometer (GC-IMS) showed that ultrasound treatment could better preserve the flavor of oysters during cold storage. Therefore, it is believed that ultrasound can inactivate foodborne pathogens of raw oysters and keep its freshness and original taste better during storage.

Optimisation of liquid smoke from water hyacinth (Eichhornia crassipes (Mart.) Solms) to preserve eels (Sybranchus bengalensis Mcclell)

Antibacterials and antioxidants are important properties of liquid smoke due to the acid, phenol, and carbonyl contents, especially for fish preservation, where these additives help in quality maintenance and shelf life extension of fishery products. Therefore, this study aimed to observe the optimisation of steaming and storage time in the liquid smoke preservation on eels. These animals were soaked with water hyacinth liquid smoke, where 35 mL of the solution was used to drench 50 g of eels at 30% concentrations. The liquid smoke used in this study was re-distilled to separate the polycyclic aromatic hydrocarbons (PAH) from the liquid smoke. The data obtained from these tests were analysed using the Response Surface Methodology (RSM), while the total plate count (TPC) and total volatile bases (TVB) were used as response variables. The results were in line with the Indonesian National Standard (SNI) No. 2725.1:2009 regarding the maximum limit for smoked eels’ TPC, where the values ranged between 2×104 - 2×105 CFU/g. The model parameters were also obtained by observing the surface regression of the TPC response with an R2 value of 87.0%. According to SNI No. 2354.8.2009 (BSN, 2009b), the TVB analysis indicated the range of values between 2.530-3.998 mg N/100 g, at approximately 140 hrs (6 days). This showed that temperature and time affected the acquisition of the TVB test by 61.6%. Therefore, the water hyacinth liquid smoke was recommended as an eels preservative based on the TPC and TVB values obtained.

Developing cold air assisted radio frequency tempering protocol based on heating rate, uniformity, and quality of frozen chicken breast

Radio frequency (RF) heating as an emerging technology has been widely used for tempering and thawing of frozen meat products, while the RF heating non-uniformity is still the main problem before industrial applications. The objective of this study was to provide a new method for improving the RF heating uniformity by adding cold air (−5 °C, 1.5 m/s) around the frozen chicken breast in a rectangular polypropylene container. The effects of cold air assisted RF tempering (CARFT), RF tempering (RFT), air tempering (AT), water tempering (WT), and refrigerator tempering (RT) on heating behaviors and quality of chicken breast were also compared. The results showed that the cold air slightly reduced the RF heating rate but significantly ( P < 0.05) improved the heating uniformity of frozen chicken breast during RFT. Meanwhile, the optimal tempering method was CARFT at the electrode gap of 110 mm, which could provide a larger heating rate than AT, WT and RT and a better heating uniformity than AT, WT and RFT. Additionally, the quality, such as color, drip loss (1.42%), pH (6.38), and total volatile base nitrogen (10.37 mg/100 g), of CARFT treated chicken breast were better than those with other methods. Therefore, CARFT can further be expanded to optimize industrial-scale RF tempering protocols in frozen chicken breast. • RF heating non-uniformity is still the main problem of industrial tempering applications. • Added cold air improved the RF heating uniformity of frozen chicken breast. • Optimal tempering method was cold air assisted RF tempering with electrode gap of 110 mm. • Quality of CARFT treated chicken breast was better than that with other methods.

Preparation of a composite-based thin film and its sensing application for detecting beef freshness

In order to improve the stability of polyphenols anthocyanidins as freshness indicator in food packaging, in this study, gellan (GL), grape-skin anthocyanidins (GSAC) and chitosan-polyvinyl alcohol (CHPA) were prepared as a composite film to protect beef and indicate the beef freshness for visual detection. The results indicated that the composite film appears good mechanical properties. The results of scanning electron microscopy showed that when the composite film were added into CHPA, the structure compatibility and stability of the film was the best. Then the complicate film was used to indicate the beef freshness and the beef was stored at 4 °C, the total volatile base nitrogen content of beef had increased continuously with the extension of storage time. After 6 days, the total volatile base nitrogen content was 35.65 mg/100 g, the thiobarbituric acid reaction product value was 1.005 mg, and pH value was 6.96. It can be seen directly with the naked eyes that the color of the film changed from dark red to mauve, and finally to blue brown, suggesting that the beef had been rotten. To sum up, the composite film made up of CHPA and gellan (GL) anthocyanin (AC) can not only reduce the oxidation of anthocyanin and improve its stability, but also be used as an indicator of meat freshness.

Three Phenolic Extracts Regulate the Physicochemical Properties and Microbial Community of Refrigerated Channel Catfish Fillets during Storage

It has been demonstrated that polyphenols have the potential to extend the shelf life of fish products. Thus, the effects of phenolic extracts from grape seed (GSE), lotus seedpod (LSPC), and lotus root (LRPE) were investigated in this study, focusing on the physicochemical changes and bacterial community of refrigerated channel catfish fillets during storage at 4 °C, using ascorbic acid (AA) as reference. As a result, GSE, LSPC, LRPE and AA inhibit the reproduction of microbials in catfish fillets during storage. According to the microbial community analysis, the addition of polyphenols significantly reduced the relative abundance of Proteobacterial in the early stage and changed the distribution of the microbial community in the later stage of storage. After 11 days of storage, the increase in total volatile base nitrogen (TVB-N) in fish was significantly reduced by 25.85%, 25.70%, 22.41%, and 39.31% in the GSE, LSPC, LRPE, and AA groups, respectively, compared to the control group (CK). Moreover, the lipid oxidation of samples was suppressed, in which thiobarbituric acid-reactive substances (TBARS) decreased by 28.77% in the GSE group, compared with the CK. The centrifugal loss, LF-NMR, and MRI results proved that GSE significantly delayed the loss of water and the increase in immobilized water flowability in catfish fillets. The polyphenol-treated samples also showed less decrease in shear force and muscle fiber damage in histology, compared to the CK. Therefore, the dietary polyphenols including GSE, LSPC, and LRPE could be developed as natural antioxidants to protect the quality and to extend the shelf life of freshwater fish.

Inhibition of Chitosan Ice Coating on the Quality Deterioration of Quick-Frozen Fish Balls during Repeated Freeze-Thaw Cycles.

Chitosan ice coating's properties and its inhibitory effect on the quality deterioration of quick-frozen fish balls during repeated freeze-thaw cycles were investigated. When the chitosan (CH) coating concentration increased, the viscosity and ice coating rate increased, while water vapor permeability (WVP), water solubility, and transmittance decreased, and 1.5% CH was regarded as the excellent coating to apply to freeze-thaw quick-frozen fish balls. As the freeze-thaw cycles increased, the frost production, total volatile base nitrogen (TVB-N) values, and free water content of all of the samples increased significantly (p < 0.05), and the whiteness values, textural properties, and water-holding capacity (WHC) decreased. Freeze-thaw cycles expanded the aperture between the muscle fibers and the occurrence of crystallization and recrystallization between cells increased, damaging the original intact tissue structure, which were confirmed by SEM and optical microscopy. Compared with the untreated ones, the frost production, free water, and TVB-N of the samples with 1.5% CH decreased during 1, 3, 5, and 7 cycles, and were reduced by 23.80%, 32.21%, 30.33%, and 52.10% by the 7th cycle. The WHC and texture properties showed an increasing trend during the freeze-thaw cycles. Therefore, the chitosan ice coating effectively inhibited the quality deterioration by reducing water loss, the occurrence of ice crystallization and recrystallization, and the pores of the samples.

Chemical, Microbiological and Sensory Characteristics of Wader Fish (Rasbora argyrotaenia) Joruk During Fermentation

Joruk is a fermented fish product typical from East Ogan Komering Ulu, South Sumatra. This study aims to determine the chemical, microbiological, and sensory properties of the joruk during fermentation, as well as to get the right fermentation time for joruk production. Research was performed by preparing joruk using wader fish. Observations included pH, total lactic acid, water content, and total volatile base (TVB), total molds and yeasts, total microbes, and total lactic acid bacteria (LAB). Furthermore, the best treatment was observed for sensory properties and protein content. Results showed that during fermentation there was a decrease in the pH value, total mold, total microbes, and water content, while the total amount of lactic acid, LAB, and TVB increased. The best treatment was obtained on joruk stored on the 10th day of fermentation with a pH value of 6.33, total lactic acid 9.48%, water content 67.74%, TVB 93.88%, and total LAB, total mold/yeast, and total microbes was respectively 10.46, 7.21, and 12,13 log CFU/g. Sensory properties for raw joruk was brown with 6.2 scale, fishy (6.4), and intact appearance (5.1). Sensory properties for cooked joruk was brown (4.2), fishy (6.7), salty taste (3.1), sour taste (8.4), and incomplete appearance (2.8).Keywords: Characteristic, joruk, wader fish, protein, TVB

Comparative Analysis of Bioactive Components of Enzymatically and Fermentatively Produced Fish Sauce from Sardine

Fish sauce, a flavored condiment produced by traditional fermentation of low-value fish. The time of fermentation and biochemical safety of sauce are the major concern in traditional fermentation. The enzymatic and fermentative methods were employed to produce Sardine (Sardinella longiceps) sauce under optimized conditions using response surface method. Salt (20%, w/w) and papain (3%, w/w) were used for enzymatic production; while, salt (25%, w/w), sugar (7.5%, w/w) and lactic culture (10%, w/v; Pediococcus pentosaceus FSBP4-40) were employed in fermentative production. Significant change in bioactive components such as pH, non-enzymatic browning, non-protein nitrogen, degree of hydrolysis, titratable acidity, total soluble nitrogen, and total volatile base nitrogen was observed in treated samples compared to the control. Total antioxidant activity (as ascorbic acid, μg/ml), percent DPPH, ABTS, and superoxide anion scavenging activities of fermented sauce were higher at 3976±90, 53.11±0.5, 99.6±0.3, 67.7±0.5 respectively; as compared to enzyme-treated samples which showed 952±70, 31.46±0.5, 76.5±1.0, 61.8±1.4 for the respective parameters, after 180 days storage. Reducing potential was found significantly higher (P&lt;0.05) in treated sauces compared to the control and fatty acid profile showed different changes. The study emphasizes the role of accelerating fermentation, either enzymatically or fermentatively, to produce biochemically and biofunctional superior Sardine sauce.

Analysis of quality changes of Hengshan goat hindquarter meat at four storage temperatures

In order to study the storage characteristics of goat meat, meat quality changes of postmortem hindquarter of Hengshan goats stored at − 20 °C for 11 months, 4 °C for 6 d, 10 °C for 60 h and 20 °C for 48 h were investigated. The microstructure, DNA quality, pH, total volatile base nitrogen (TVB-N), meat color, texture, water holding capacity (WHC) and fatty acid content were determined. Correlations between pH, TVB-N and other indicators which might be affected by both were analyzed. Results showed that the changing trends of indicators at four storage temperatures were generally consistent; pH first declined and then rose, whereas the meat color showed the opposite trend (P < 0.05); TVB-N basically reached 15 mg/100 g when the pH reached the minimum (P < 0.05); Texture profile, WHC and fatty acid content decreased with storage (P < 0.05); DNA quality declined at the later stage of storage. Correlation analysis indicated that the pH, TVB-N were little correlated with DNA quality, and negatively correlated with other indicators in general (P < 0.05); the pH was mainly negatively related to meat color (P < 0.05); TVB-N was mainly related to texture and fatty acid content, and the correlation strengthened as the pH increased (P < 0.05). This study revealed the considerable effect of TVB-N value on meat quality changes during pH rising, and provided new insights for assessing meat quality at different storage phases.

Assessment of quality and shelf-life of salt-smoked cured products from Pangasius catfish at various temperatures

Pangasius catfish (Pangasianodon hypophthalmus) is popularly cultured in Bangladesh but the farmers usually suffer financial losses due to their low market price. Development of new value-added products will enhance its popularity and acceptability to the consumers. This study was conducted to develop smoked products from pangasius catfish, to evaluate their quality and shelf-life at ambient (30-35°C) and refrigeration temperatures (4°C). Two treatments, dipped for 15 min in 10% (T1) and 15% (T2) salt solutions, and one untreated control were maintained. The smoking was conducted at 70-75°C in an improved traditional smoking kiln. The products were then sealed in polybags and stored separately at ambient and refrigeration temperatures. The sensory quality, proximate composition, salt content, total volatile base nitrogen (TVB-N) values, and viable bacterial counts were determined. The products stored at ambient temperature were rejected on day 5, 7 and 9; and those kept at refrigeration temperature, on day 28, 35, and 42, respectively for control, T1, and T2. Significant difference in proximate composition was observed between the treatments, storage conditions and periods. The TVB-N values were increased rapidly in control followed by the T1 samples, compare to T2 samples. Viable bacterial counts of the smoked products were gradually increased with the increasing storage periods. Considering all the assessed parameters, the T2 products were better in quality with longer shelf-life than those of control and T1. As consumers’ preference towards new fishery products has been changing, smoked products from pangasius catfish will be preferred for their taste, less bones, and higher shelf-life.

Quality changes when replacing NaCl with KCl in shrimp head paste

Traditional shrimp paste was produced by Litopenaeus vannamei head as a low-priced by-product instead of the tradition raw material. Partial replacement of sodium chloride with potassium chloride at 0%, 30% and 50% was done to reduce risk of hypertension. The reduction of aw and increment of pH, total volatile bases nitrogen (TVB-N), trimethylamine (TMA), thiobarbituric acid reactive substances (TBARS) and degree of hydrolysis (DH) were found in all treatments. After fermentation for 90 d, total viable count (TVC) and lactic acid bacteria (LAB) decreased, with no pathogenic microorganisms found. Angiotensin-converting enzyme (ACE) Inhibition (%) of shrimp head was close to captopril at 2.17 ng/mL but lower than shrimp head paste and captopril at 4.35 ng/mL. Sensory score of all treatments were lower than that of commercial shrimp paste. Partial replacement of sodium chloride with potassium chloride at 50% can be done in shrimp head paste but further study required to improve consumer acceptability.

Incorporation of Neolamarckia cadamba leaf extract into chitosan coating for maintaining the quality of white shrimp (Litopenaeus vannamei)

Neolamarckia cadamba or locally known as kelampayan or laran is traditionally used for treatments of illnesses such as diabetes, anaemia and cancer. This plant has been reported for its phytochemical compounds which include alkaloids, phenolics and flavonoids as well as various bioactivities such as antioxidant, antibacterial and anti-inflammatory activity. Despite its use as a medicinal plant, information on the possible utilization for controlling the quality of food is scarce. This study aimed at exploring the efficacy of N. cadamba leaf extract incorporated into a coating solution at different concentrations (1%, 2% and 3%) for retaining the quality of white shrimp in chilled storage. Assessment of physical, chemical, microbial quality, melanosis formation and sensory analysis of the white shrimp was performed during 9 days of storage at 4°C. Following treatment of the coating solution on white shrimp, weight loss and pH values were recorded. Total volatile base nitrogen was assessed using the distillation method, and shrimp quality and melanosis formation were scored through visual inspection. In the sensory acceptance test, panellists assessed the appearance, colour, odour, texture and overall acceptance of shrimp using a nine-point hedonic scale. This study reported that the coating solution incorporated with N. cadamba leaf extract at all tested concentrations significantly (p&lt;0.05) retarded the percentage of weight loss, decreased total volatile base nitrogen and delayed melanosis formation in white shrimp. The application of the coating with the incorporation of N. cadamba leaf extract also showed a higher score in quality assessment and better sensory acceptance of white shrimp. Neolamarckia cadamba leaf extract in the coating also presented a positive implication towards reduced growth of microorganisms in the white shrimp. This study, therefore, showed the potential of N. cadamba leaf extract as an agent for postharvest treatment to retain the quality of white shrimp.

STUDY OF QUALITY CHANGES IN Clarias gariepinus (BURCHELL 1822) STORED IN MODIFIED ICE FISH BOXTM

Fish is a very perishable commodity that deteriorates after harvest without proper handling, transportation, and storage. Nigerian Stored Products Research Institute Ice Fish BoxTM has been improved to have a greater capacity for more storage of fish as well as the development of a trolley to ease movement and a change in position of the drain spot increasing the performance of the drainage system. Thirty (30) kilograms of freshly harvested Clarias gariepinus and thirty (30) kilograms of ice were layered alternately at a ratio 1:1 in the modified box for pH, total volatile base nitrogen (TVBN), trimethylamine (TMA), total viable count (TVC) and freshness evaluation using Quality Index (QI) at a sampling period of 24 hours and sensory evaluation of processed fish using Likert scale. C. gariepinus, stored for a maximum of 48 hours with pH between 6.70 and 7.17, TVBN, 5.52 - 8.25 mg/100 g, TMA, 0.84- 2.33 mg/100g, TVC, 1.0x102 - 3.8x103 cfu/g, QI, 7 and sensory evaluations were above 4. The quality indices were within acceptable limits. It is anticipated that this would lower the amount of loss that occurs after harvest thus boosting revenues in the fish value chain and improving food and nutritional security

Efficacy of vitamin E with or without probiotic, astaxanthin or rosemary extract on microbiological and chemical characteristics of fresh and frozen fillet of rainbow trout (Oncorhynchus mykiss)

Microbiological properties, proximate composition, total volatile base nitrogen (TVB-N), pH, fatty acid (FA) composition, peroxide value (PV), free fatty acids (FFA), histamine and water holding capacity (WHC) in fresh and frozen-stored (3, 6, and 12 months at −18 °C) fillets of rainbow trout (Oncorhynchus mykiss) (170.46 ± 1.16 g) fed diets containing 50 mg vitamin E (control) alone or with 200 mg vitamin E (VE), 500 mg probiotic (PR), 50 mg astaxanthin (AS) and 500 mg rosemary extract (RE) kg−1 for 4 months were assessed. Decreasing trends in fillet WHC (specially in control and AS groups) were observed in the 12-month storage. Although a low increase in fillet bacterial population occurred during the storage time in all groups, lower bacterial counts were observed in PR group. Fillet histamine, TVN and pH levels were in the accepted ranges in all treatments during the storage. Also, FFA level and proximate composition of fillets didn’t show any significant change during the storage time. The PR diet controlled microbiological activity and variations of pH and PV of fillet samples better than the other experimental diets. It also prepared an appropriate FA composition and retained the desired amounts of both n-3 and n-6 polyunsaturated fatty acids (PUFAs) in fish fillets until the end of storage period, while no significant differences were seen in values of TVN, pH, FFA and histamine among the treatments. However, AS and RE diets tended to be less functional maintaining the fillet quality during the storage time than the other experimental diets. According to the results, a diet containing 500 mg bacilli probiotic with 50 mg vitamin E kg−1 could be highly efficient in maintaining a good quality of trout fillet stored at − 18°C for 12 months.

Effect of Baking Temperature and Time on Advanced Glycation End Products and Polycyclic Aromatic Hydrocarbons in Beef

Beef is an important red meat that contains essential nutrients for human growth and development. Baking is a popular beef cooking method. Temperature and time play key roles in the final quality of beef. How temperature and time affect the changes of nutrients and the formation of harmful products in beef is not clear. The purpose of this study was to measure the content of water, fat, protein, ash, nitrite, total volatile base nitrogen, advanced glycation end products (AGEs) and their precursors, and polycyclic aromatic hydrocarbons (PAHs) at different temperatures (150, 190, 230, 270, and 310°C) for 20 min and at 190°C for different times (10, 20, and 30 min), so as to discuss the effect of different temperatures and times on beef nutrients and harmful products. The results showed that the moisture content of beef decreased with increased baking temperature and time, resulting in the increase of the relative content of fat, protein, and ash. The content of total volatile base nitrogen increased continuously. Compared with the control group, the content of glyoxal in beef decreased, whereas the content of methylglyoxal, pentosidine, and fluorescent AGEs increased, indicating the continuous accumulation of AGEs in beef. A total of 13 PAHs were identified by gas chromatography-mass spectrometry. The concentrations of 13 PAHs in beef increased with increases in baking temperature and time. The concentrations of BkP and BaP, which are the most carcinogenic to humans, were 0.36 and 0.35 μg/kg in raw meat, respectively; these were increased by high temperature and long baking times. After beef was baked at 270 and 310°C for 20 min, the concentration of BkP increased to 9.49 and 5.66 μg/kg, respectively, and the concentration of BaP increased to 5.45 and 4.42 μg/kg, respectively. After baking at 190°C for 30 and 40 min, the concentration of BkP increased to 4.81 and 24.20 μg/kg, respectively, and the concentration of BaP increased to 3.85 and 17.79 μg/kg, respectively.