Total Amine Research Articles

Improvement of the quality stability of vacuum‐packaged fermented fish (Suanyu) stored at room temperature by irradiation and thermal treatments

SummaryTo evaluate the effects of irradiation and thermal treatments on the quality characteristics of the vacuum‐packaged low‐salted fermented fish (Suanyu) during 90‐day storage, thermal‐treated group (TTG), irradiated‐treated group (ITG) and non‐treated group (CG) were prepared. The results showed that total viable counts reduced by 4.49 and 4.67 log CFU/g after thermal and irradiation treatments, respectively, and no coliforms and pseudomonas growth occurred during storage. Compared with CG, lower levels in L*, springiness, chewiness of TTG and higher levels in L*, b* and chewiness of ITG were detected after 90‐day storage. Total biogenic amines content was significantly reduced in ITG compared with CG and TTG (P < 0.05). Both irradiation and thermal treatments have the potential to maintain quality of Suanyu during room storage. Compared with irradiation, thermal treatment could better stabilise the free amino acids and volatile compounds of Suanyu during room storage, but had some negative effects on texture quality.

Effect of Storage Conditions on Microbiological Characteristics, Biogenic Amines, and Physicochemical Quality of Low-Salt Fermented Fish

The present study was conducted to evaluate the effects of long-term storage at various temperatures (4, 25, and 35°C) on flavor and microbiological and physicochemical qualities of traditional Chinese low-salt fermented fish (Suanyu). Food spoilage and pathogenic bacteria (coliforms, Pseudomonas, and Salmonella) were inhibited during the 90 days of storage at all temperatures. Lactic acid bacteria, yeast, and total viable bacteria counts of samples stored at 35°C were reduced sharply, whereas other parameters were stable. Compared with refrigerated storage (4°C), higher storage temperatures (25 and 35°C) accelerated moisture migration, lipid oxidation, and proteolytic degradation. Storage time had a greater effect than storage temperature on the increase of volatile compounds in Suanyu. Refrigerated storage was better than higher storage temperatures (25 and 35°C) for maintaining the odor quality of Suanyu during the storage period. Total biogenic amine concentrations in all samples were ≪200 mg/kg. Suanyu can be consumed safely during 90 days of storage based on the levels of spoilage and pathogenic bacteria and concentrations of biogenic amines, but refrigerated storage effectively slows down the microbial and physicochemical changes, resulting in better organoleptic quality. The results of this study will be useful for processors controlling the safety and quality of fermented fish during transport and storage.

Viscosity Measurement and Correlation of Unloaded and CO2-Loaded Aqueous Solutions of N-Methyldiethanolamine + 2-Amino-2-methyl-1-propanol

This work contributes to new and complementary experimental viscosity data for blended amine mixtures of aqueous N-methyldiethanolamine + 2-amino-2-methyl-1-propanol (MDEA + AMP) solutions with and without CO2 at different temperatures and mass fractions. For the unloaded MDEA + AMP solutions, measurements were conducted with total amine mass fractions ranging from 0.30 to 0.60. In the case of CO2-loaded aqueous MDEA + AMP solutions, experiments were performed at CO2 loadings ranging from 0.11 to 0.80. Proposed correlations were used to represent viscosity at the unloaded and CO2-loaded solutions within experimental uncertainty.

Challenges Associated with Byproducts Valorization-Comparison Study of Safety Parameters of Ultrasonicated and Fermented Plant-Based Byproducts.

In order to promote the efficient use of byproducts from the production of plant-based beverages, which still contain a large amount of nutritional and functional compounds, microbiological and chemical safety characteristics should be evaluated and, if needed, improved. Many challenges are associated with byproducts valorization, and the most important ones, which should be taken into account at the further steps of valorization, are biological and chemical safety. For safety improving, several technological treatments (biological, physical etc.) can be used. In this study, the influence of low-frequency ultrasonication (US) and fermentation with Lactobacillus casei LUHS210 strain, as physical and biotechnological treatments, on the safety characteristics of the byproducts (BYs) from the processing of rice, soy, almond, coconut, and oat drinks was compared. Ultrasonication, as well as fermentation, effectively improved the microbiological safety of BYs. Ultrasonication and fermentation reduced the concentration of deoxynivalenol, on average, by 24% only in soy BYs. After fermentation, 15-acetyldeoxynivalenol was formed in all samples (<12 µg kg−1), except for soy BYs. The lowest total biogenic amines content was found in fermented rice BYs and ultrasonicated coconut BYs. When comparing untreated and fermented BYs, significant changes in macro- and micro-elements content were found. Ultrasonication at 37 kHz did not significantly influence the concentrations of macro- and micro-elements, while fermentation affected most of the essential micro-elements. Consequently, while ultrasonication and fermentation can enhance the safety of BYs, the specific effects must be taken into account on biogenic amines, mycotoxins, and micro and macro elements.

Effects of different strains and fermentation method on nattokinase activity, biogenic amines, and sensory characteristics of natto.

Nattokinase activity(NK), biogenic amine content and sensory properties of natto are of great significance to consumers, which are affected by strains and fermentation methods. In this study, changes in the pH, biogenic amine and free amino nitrogen (FAN) contents, NK and protease activities, and sensory characteristics of natto prepared using Bacillus subtilis GUTU09 combined with different strains (Lactobacillus, Bifidobacterium and Mucor) and fermentation methods were investigated. The combination of two strains showed the best fermentation performance among all samples. The NK and protease activity and FAN content in double-strain fermentation increased by 10.33FU/g, 88.78U/g, and 2.34g/kg, respectively, compared with those in single-strain fermentation. Sensory evaluation demonstrated that mixed fermentation primarily affected the sensory acceptance. This method also reduced the contents of various biogenic amines in natto compared with single-strain fermentation. Tyramine, cadaverine, spermine, and spermidine were significantly reduced, whereas histamine was slightly increased. The total biogenic amines decreased from 390.76mg/kg to a minimum of 16.16mg/kg. Some Mucor strains also reduced the contents of various biogenic amines. In the dual-bacteria fermentation of Mucor and GUTU09, co-fermentation has advantages over stage-fermentation, with higher NK and protease activity and higher sensory scores. Correlation analysis showed that the formation and accumulation of some biogenic amines in natto prepared using different microbial combinations were related to NK activity and pH. All these results showed that the quality of natto was improved by mixed fermentation and suitable fermentation methods, which laid a foundation for its potential industrial application.

Influence of pomegranate seed extract on the formation of biogenic amines in a cereal based fermented food: Tarhana.

In this research, biogenic amine content, acidity, pH values, total free amino acid content (TFAA), ash content, colour values (CIE L*, a*, b*), total phenolic compound content (TPCC) and antioxidant activity values of tarhana, which were fortified with pomegranate seed extract (PSE) in different ratios (0%, 0.5%, 1%, 2%) were evaluated during six months of storage. It has been evaluated that pomegranate seed extract causes increase on TPCC, ash content and antioxidant activity values. Putrescine, cadaverine, spermidine, spermine, histamine, tyramine were studied as biogenic amines. Standard addition and internal standard techniques were performed for quantification of biogenic amines. Recovery rates were found between 87.0% and 94.6%. Total biogenic amine contents of tarhana samples decreased during the first two months of storage, remained constant and increased slightly for the next four months. It was found that, pomegranate seed extract causes decrease on biogenic amine content of tarhana samples. While the average total biogenic amine content in control group was 894.70mg/kg, tarhana samples which were fortified with pomegranate seed extracts in ratios of 0.5%, 1%, 2% contained 569.67mg/kg, 514.52mg/kg, 424.60mg/kg total biogenic amine, respectively.

Tryptophan pathway catabolites (serotonin, 5-hydroxyindolacetic acid, kynurenine) and enzymes (monoamine oxidase and indole amine 2,3 dioxygenase) in patients with septic shock: A prospective observational study versus healthy controls.

Septic shock is associated with a strong inflammatory response that induces vasodilation and vascular hyporeactivity. We investigated the role for tryptophan-pathway catabolites of proinflammatory cytokines in septic shock.We prospectively included 30 patients with very recent-onset septic shock and 30 healthy volunteers. The following were assayed once in the controls and on days 1, 2, 3, 7, and 14 in each patient: plasma free and total tryptophan, platelet and plasma serotonin, total blood serotonin, urinary serotonin, plasma and urinary 5-hydroxyindolacetic acid, plasma kynurenine, monoamine oxidase activity, and total indole amine 2,3-dioxygenase activity. Organ-system failure and mortality were recorded.Compared with the healthy controls, the patients with septic shock had 2-fold to 3-fold lower total tryptophan levels throughout the 14-day study period. Platelet serotonin was substantially lower, while monoamine oxidase activity and 5-hydroxyindolacetic acid were markedly higher in the patients than in the controls, consistent with the known conversion of tryptophan to serotonin, which is then promptly and largely degraded to 5-hydroxyindolacetic acid. Plasma kynurenine was moderately increased and indole amine 2,3-dioxygenase activity markedly increased in the patients versus the volunteers, reflecting conversion of tryptophan to kynurenine. Changes over time in tryptophan metabolites were not associated with survival in the patients but were associated with the Sequential Organ Failure Assessment score and hemodynamic variables including hypotension and norepinephrine requirements.Our results demonstrate major tryptophan pathway alterations in septic shock. Marked alterations were found compared with healthy volunteers, and tryptophan metabolite levels were associated with organ failure and hemodynamic alterations. Tryptophan metabolite levels were not associated with surviving septic shock, although this result might be ascribable to the small sample size.Trial registration: ClinicalTrials.gov; No: NCT00684736; URL: www.clinicaltrials.gov.

Lactobacillus plantarum LPL-1, a bacteriocin producing strain, changed the bacterial community composition and improved the safety of low-salt fermented sausages

The reduction of salt (sodium chloride) in fermented sausages is motivated by the positive association between excessive intake of sodium and some diseases. However, pathogens control and shelf life of fermented sausages is of vital importance when salt is reduced. In this study, we investigated the impacts of an IIa bacteriocin-producing strain, Lactobacillus plantarum LPL-1, on the composition of bacterial community in low-salt fermented sausages by using a culture-independent high-throughput sequencing approach. Meanwhile, impacts of LPL-1 on physicochemical characteristics of low-salt fermented sausages were investigated. Our results showed that LPL-1 changed the bacterial community composition, reduced community diversity and inhibited the growth of spoilage bacteria during fermentation and ripening of low-salt fermented sausages. After fermentation, Lactobacillus was the most abundant genus with the proportion over 90% in sausages which inoculated with LPL-1. We predicted microbial metabolism related to nutrients transport and metabolism enhanced in sausages by inoculating with LPL-1. We also found that the decrease of pH and tyramine, putrescine and cadaverine and total biogenic amines content in sausages inoculated with LPL-1. These findings indicated that L. plantarum LPL-1 can be applied as starter culture to improve the safety of low-salt fermented sausages.

Impact of Nisin-Producing Strains of Lactococcus lactis on the Contents of Bioactive Dipeptides, Free Amino Acids, and Biogenic Amines in Dutch-Type Cheese Models.

The goal of this study was to determine changes in contents of free amino acids, biogenic amines, and bioactive dipeptides (anserine and L-carnosine) in cheese models produced with the addition of nisin-producing strains of Lactococcus lactis over their ripening period. After 5 weeks of ripening, contents of total biogenic amines in the cheese models with the addition of L. lactis strains were lower than in the control cheese model. The cheese models examined differed significantly in contents of free amino acids through the ripening period. Individual free amino acids, such as ornithine, were found in some of the cheese models, which is indicative of their specific microbial activities. Both anserine and L-carnosine were detected in all variants of the cheese models. After 5-week ripening, the highest total content of bioactive dipeptides was determined in the cheese models produced with the nisin-producing culture of L. lactis 11454 (142.15 mg∙kg−1).

Shape recoverable and mechanically robust cellulose aerogel beads for efficient removal of copper ions

• One-pot synthesis of cross-linked aerogel beads. • Efficient adsorption of copper ions by the beads. • Mechanical testing confirmed beads were robust. • Aerogel beads could be regenerated and recycled. Developing bio-based absorbents with high removal capacity towards heavy metals is one of the key strategies to manage water pollution worldwide. Robust cellulose aerogel beads (CGP, diameter of 3–4 mm) with high amine content were prepared by cross-linking polyethylenimine (PEI) to cellulose nanofibrils (CNF) using 3-glycidyloxypropyl) trimethoxysilane (GPTMS). The mass ratio between PEI and GPTMS (1:1 or 3:1), crosslinking mechanism, morphologies, elemental compositions, total amine contents, mechanical strengths as well as the adsorption capacity and kinetic of the aerogel beads were investigated. Small CGP beads possessed several desirable characteristics, such as high amine group content (5.74 mmol/g for CGP3 beads), large maximum Cu (II) adsorption capacity (163.40 mg/g for CGP3 beads), very fast adsorption rate (<10 h to reach equilibrium), high shape recovery (2.00% plastic deformation for CGP3 beads at 50% strain), robust mechanical strength (stress around 10.5 KPa at 50% strain), and they could be regenerated and reused.

Combined Treatments of High Hydrostatic Pressure and CO2 in Coho Salmon (Oncorhynchus kisutch): Effects on Enzyme Inactivation, Physicochemical Properties, and Microbial Shelf Life.

This study focused on applying different high hydrostatic pressure + carbon dioxide (HHP + CO2) processing conditions on refrigerated (4 °C, 25 days) farmed coho salmon (Oncorhynchus kisutch) to inactivate endogenous enzymes (protease, lipase, collagenase), physicochemical properties (texture, color, lipid oxidation), and microbial shelf life. Salmon fillets were subjected to combined HHP (150 MPa/5 min) and CO2 (50%, 70%, 100%). Protease and lipase inactivation was achieved with combined HHP + CO2 treatments in which lipase activity remained low as opposed to protease activity during storage. Collagenase activity decreased approximately 90% during storage when applying HHP + CO2. Combined treatments limited the increase in spoilage indicators, such as total volatile amines and trimethylamine. The 150 MPa + 100% CO2 treatment was the most effective at maintaining hardness after 10 days of storage. Combined treatments limited HHP-induced color change and reduced the extent of changes caused by storage compared with the untreated sample. Microbial shelf life was extended by the CO2 content and not by the HHP treatments; this result was related to an increased lag phase and decreased growth rate. It can be concluded that combining HHP and CO2 could be an effective method of inactivating endogenous enzymes and extend salmon shelf life.

Determination of Biogenic amines in hard cheeses by High performance liquid chromatography

This study evaluated chemically the quantity of six biogenic amines histamine, tyramine, puterscine, cadaverine, tryptamine and phenylethylamine in forty hard cheese samples (Chedder and Ras) (20 of each) sold in retail markets in Zagazig City Sharkia Governorate using high performance liquid chromatography (HPLC) and correlation with compositional quantity of cheese (pH, salt%, moisture% and acidity%). Our results showed the mean values of pH, salt, moisture and acidity were (5.5±0.02 and 4.79±0.11), (1.53±0.04 and 4.42±0.05%), (40.45±0.24 and 38.64±0.34%) and (0.84 ±0.01 and 1.70±0.04%) in Chedder and Ras cheese samples, respectively. The mean values of total biogenic amines were 12.65±2.7and 28.95±4.6 mg/100g in Chedder and Ras cheese samples, respectively. There was a negative correlation between (pH value and moisture %) and biogenic amines production but the positive correlation was found between (salt and acidity %) and biogenic amines production. Finally it was found that all Chedder and Ras cheese samples were accepted according to maximum permissible limit of Egyptian organization standard (EOS, 2007) which is 20mg/100g. All samples were accepted according to maximum permissible limit of Food and Drug Administration (FDA, 2001) which is 10mg/100g except 60 and 90 % of Ras cheese samples are accepted for histamine and puterscine, respectively. On conclusion, optimization and standardization of milk quality and hygiene during cheeses manufacturing and storage should be taken for human safety.

Characterization, Seasonal Variation, and Source Apportionments of Particulate Amines (PM2.5) in Northern Suburb of Nanjing

PM2.5 samples were collected from December 2017 to November 2018 at a northern suburb site of Nanjing. The concentrations of five amines, major water-soluble ions, organic carbon, and elemental carbon were determined. The five amines measured were methylamine, ethylamine, dimethylamine, trimethylamine, and aniline. The annual average of the total amine concentration was (54.2±29.2) ng·m-3. Among these, dimethylamine was the most abundant[annual average:(20.2±13.7) ng·m-3], followed by methylamine[annual average:(13.1±6.3) ng·m-3], trimethylamine[annual average:(8.6±4.1) ng·m-3], ethylamine[annual average:(6.3±4.1) ng·m-3], and aniline[annual average:(5.9±3.9) ng·m-3]. The total amine concentration showed explicit seasonal variations:summer > autumn > spring > winter. The amine concentration on polluted days was higher than that on clean days. This may be influenced by aerosol acidity, promoting the partitioning of gaseous amine into the particulate phase. Aerosol acidity was also the major reason for the higher concentration of amine observed in summer than in other seasons. During new particle formation events, the concentrations of amines increased substantially. Positive matrix factorization (PMF) was utilized to identify the potential sources of amines, identifying six sources:industrial emission, agriculture emission, biomass burning, automobile emission, secondary formation, and dust. Methylamine and ethylamine mainly originated from secondary formation and automobile emissions. Dimethylamine and trimethylamine mainly originated from biomass burning, secondary formation, and automobile emissions; Aniline mainly originated from industrial emissions and biomass burning. A significant seasonal difference is observed with respect to the sources of amines. In spring and autumn, road dust sources account for a relatively high proportion. In summer, secondary sources are the main sources of amines. However, the diurnal variations of amine are not evident, and the secondary source, motor vehicle emission, and biomass combustion are the three main influencing factors.

Effect of γ-aminobutyric acid producing bacteria on in vitro rumen fermentation, growth performance, and meat quality of Hanwoo steers.

ObjectiveThe present study aimed to evaluate the effects of γ-aminobutyric acid (GABA)-producing bacteria (GPB) on in vitro rumen fermentation and on the growth performance and meat quality of Hanwoo steers.MethodsThe effects of GPB (Lactobacillus brevis YM 3-30)-produced and commercially available GABA were investigated using in vitro rumen fermentation. Using soybean meal as a substrate, either GPB-produced or commercially available GABA were added to the in vitro rumen fermentation bottles, as follows: control, no additive; T1, 2 g/L GPB; T2, 5 g/L GPB; T3, 2 g/L autoclaved GPB; T4, 5 g/L autoclaved GPB; T5, 2 g/L GABA; and T6, 5 g/L GABA. In addition, 27 Hanwoo steers (602.06±10.13 kg) were subjected to a 129-day feeding trial, during which they were fed daily with a commercially available total mixed ration that was supplemented with different amounts of GPB-produced GABA (control, no additive; T1, 2 g/L GPB; T2, 5 g/L GPB). The degree of marbling was assessed using the nine-point beef marbling standard while endotoxin was analyzed using a Chromo-Limulus amebocyte lysate test.ResultsIn regard to in vitro rumen fermentation, the addition of GPB-produced GABA failed to significantly affect pH or total gas production but did increase the ammonia nitrogen (NH3-N) concentration (p<0.05) and reduce total biogenic amines (p<0.05). Animals fed the GPB-produced GABA diet exhibited significantly lower levels of blood endotoxins than control animals and yielded comparable average daily gain, feed conversion ratio, and beef marbling scores.ConclusionThe addition of GPB improved in vitro fermentation by reducing biogenic amine production and by increasing both antioxidant activity and NH3-N production. Moreover, it also reduced the blood endotoxin levels of Hanwoo steers.

Equilibrium Solubility Measurement and Modeling of CO2 Absorption in Aqueous Blend of 2-(Diethyl amino) Ethanol and Ethylenediamine

The equilibrium CO2 solubility in an aqueous blend of 2-(diethyl amino) ethanol (DEEA) and ethylenediamine (EDA) was performed at atmospheric pressure with the use of a laboratory scale bubbling absorber. The total concentration of amine blend solution in the range of 1.13–4.90 mol·kg–1 and the EDA mole fraction in the total amine blend in the range of 0.05–0.20 were taken. The experiments for the measurement of CO2 solubility were performed at a temperature range of 303.15–333.15 K and CO2 partial pressure range of 10.13–20.27 kPa. The analysis of CO2 in the liquid phase was accomplished by a direct titration method using HCl solution. The solubility data of CO2 in DEEA+EDA solution of the present study were compared with data available in the literature. The experimental results were applied to develop an empirical mathematical model with an average absolute deviation of 7.03% to predict the CO2 equilibrium solubility in DEEA+EDA solution within the specified range of operating conditions. In addition, ...

Effect of microwave sterilization on maturation time and quality of low-salt sufu.

The objective of this study was to reduce the microorganism number and salt content in pehtze by microwave sterilization. The maturation time and quality of low‐salt sufu were evaluated. The microorganism inactivation rate, moisture content and water activity of the pehtze, which was used for the growth of the starter culture, showed that 4,250 W for 30 s was suitable for the preparation of low‐salt sufu. With regard to the physicochemical properties of sufu, 120‐day sufu samples obtained by traditional high‐salt (14%) fermentation and 75‐day sufu samples obtained by low‐salt (4%) fermentation met the standard requirements. With regard to the sensory characteristics of sufu, the taste and after taste scores of 75‐day low‐salt sufu samples were significantly higher than those of 120‐day high‐salt sufu samples (p < .05).The overall acceptance score of low‐salt sufu samples also was higher than that of high‐salt sufu samples. The contents of free amino acids and the profiles of typical flavor compounds partly explained the sensory quality and shorter ripening time of sufu manufactured. The total biogenic amine contents were reduced by 46%.

Effects of Soaking and Fermentation Time on Biogenic Amines Content of Maesil (Prunus Mume) Extract.

Maesil extract, a fruit-juice concentrate derived from Prunus mume prepared by fermenting with sugar, is widely used with increasing popularity in Korea. Biogenic amines in maesil extract were extracted with 0.4 M perchloric acid, derivatized with dansyl chloride, and detected using high-performance liquid chromatography. Among 18 home-made maesil extracts collected from different regions, total biogenic amine content varied from 2.53 to 241.73 mg/L. To elucidate the effects of soaking and fermentation time on biogenic amine content in maesil extract, maesil was soaked in brown sugar for 90 days and the liquid obtained was further fermented for 180 days at 15 and 25 °C, respectively. The main biogenic amines extracted were putrescine and spermidine and the total biogenic amine content was higher at 25 °C than at 15 °C. Soaking at 15 and 25 °C increased the total biogenic amines content from 14.14 to 34.98 mg/L and 37.33 to 69.05 mg/L, respectively, whereas a 180 day fermentation decreased the content from 31.66 to 13.59 mg/L and 116.82 to 57.05 mg/L, respectively. Biogenic amine content was correlated with total amino acid content (particularly, arginine content). Based on these results, we have considered that biogenic amine synthesis can be reduced during maesil extract production by controlling temperature and fermentation time.

Genipin-Aided Protein Cross-linking to Modify Structural and Rheological Properties of Emulsion-Filled Hempseed Protein Hydrogels.

Genipin, a natural electrophilic cross-linker, was applied (5, 10, 20, and 30 mM) to modify hempseed protein isolate (HPI). Genipin treatments resulted in general losses of total sulfhydryls (up to 2.9 nmol/mg) and free amines (up to 77.3 nmol/mg). Surface hydrophobicity decreased by nearly 90% with 30 mM genipin, corresponding to similar tryptophan fluorescence quenching. The genipin treatment converted HPI into highly cross-linked polymers. Hydrogels formed with such polymers when also incorporated with hemp oil emulsions exhibited substantially enhanced gelling ability: up to 3.3- and 2.6-fold increases, respectively, in gel strength and gel elasticity over genipin-untreated protein. The genipin-modified composite gels also exhibited superior water-holding capacity. Microstructural analysis revealed a compact gel network filled with protein-coated oil globules that interacted intimately with the protein matrix when treated with genipin. Such gels remained readily digestible. Hence, genipin-treated hemp protein hydrogels show promise as functional food components.

Functional aromatic polyamides for the preparation of coated fibres as smart labels for the visual detection of biogenic amine vapours and fish spoilage

We have prepared high-performance functional aromatic polyamides with sensory pendant groups toward amines. These polymers are colourless. The pendant groups have bromonaphthalimide motifs that react with amines rendering coloured arylamines by nucleophilic aromatic substitution of the halide. Thus, these materials are colorimetric sensors toward amines. In the interest of saving costs, while having a sensory material with a high specific surface, cotton fabrics were coated, in order to render coated fibres as smart colorimetric labels toward amines. Moreover, as fish spoilage by microorganism increases the biogenic amines in food, we have applied the smart labels to visually follow the food spoilage. Also, a picture taken to the films allowed to obtain, in seconds, the digital colour definition parameters (RGB) that were correlated with the results of expensive and time-consuming conventional techniques used to obtain relevant food quality data, such as total amine concentration (treatment of the sample and HPLC), colony-forming unit (microbiological assays), total volatile basic nitrogen (TVB-N), and organoleptic test (sensory test). The smart labels are inexpensive, granting in seconds the visual qualitative evaluation of the food quality, or even quantitative, and they comply with the European food contact materials regulation.

Improvement of gel properties of mackerel mince by phlorotannin extracts from sporophyll of Undaria pinnatifidai and UVA induced cross-linking.

The effects of phlorotannin extracts (PTE) (from sporophyll of Undaria pinnatifida) added at different concentration (0, 1.6, 8, and 40 mg/g protein) with and without ultraviolet A (UVA) irradiation treatment on gel properties of mackerel (Scomberomorus niphonius) mince (MM) were investigated. The results indicated that both the breaking force and water-holding capacity (WHC) of the MM gel increased with addition of PTE, and the highest breaking force and WHC were observed with 40 mg/g PTE under UVA irradiation. Low-field nuclear magnetic resonance revealed that free water significantly decreased in this PTE-MM gel as well. UVA irradiation treatment led to reduction of total sulfhydryls and free amines in the PTE-MM gel, indicating more cross-linking between proteins. Electrophoresis results indicated that myosin heavy chains were aggregated in the UVA-treated PTE-MM gel. The microstructure of the UVA-treated PTE-MM gel showed that protein formed more evenly distributed cross-linked structures and was more compact than the untreated control gel. As a conclusion, PTE addition with UVA irradiation is shown to improve gelling properties of mackerel mince.