In vitro (31)P NMR studies on biopsy skeletal muscle samples compared with meat quality of normal and heterozygous malignant hyperthermia pigs

Phosphorus nuclear magnetic resonance ((31)P NMR) measurements were made to determine muscle energetic metabolism on muscle biopsy samples of heterozygote malignant hyperthermia (Nn) and normal (NN) pigs DNA tested on occurrence of mutation in RYR 1 gene. Biopsy samples (approx. 1 g) were obtained by spring-loaded biopsy instrument (Biotech, Slovakia) from Longissimus dorsi (LD) muscle at 80 kg live weight. The spectra were recorded at 121 MHz on a VXR 300 (Varian) spectrometer in 10 mm diameter tube (maintained at 39?°C) for 50 min. pH of bioptates after NMR measurements were also measured at 60 min. The changes in inorganic phosphate (Pi), phosophocreatine (PCr) and adenosine triphosphate (ATP) were faster in heterozygote malignant hyperthermia (MH; 29 crossbred White Meaty×Pietrain) than in normal (13 Duroc, Yorkshire and White Meaty). The values of PCr at 20 min and pH at 60 min after taking biopsy allowed discrimination between NN and Nn pigs and significant (P<0.05) differences were also found between two subgroups in heterozygote MH pigs with different rate of post mortem muscle metabolism. The values of PCr and pH as measured at definite time on the biopsies, were significantly (P<0.05) correlated with the rate of post mortem metabolism (pH) and with meat quality traits (r approx. 0.4-0.6). The (31)P NMR measurements pointed to impaired muscle energetic metabolism connected with the occurrence of mutation on the RYR 1 gene in heterozygote MH pigs.     

Effects of Rested Harvesting on Muscle Metabolite Concentrations and K-Values in Chinook Salmon (Oncorhynchus tshawytscha) Fillets during Storage at 15 °C

Abstract: Improvement of harvesting procedures in aquaculture may also improve the quality and storage properties of the fish. The use of an anesthetic allows fish to be harvested with reduced stress and exhaustion, which affect fillet properties. We report here on the effects of rested harvesting on the postharvest metabolic profiles and K-values in Chinook salmon (Oncorhynchus tshawytscha) fillets stored near to the fish's acclimation temperature at 15 °C for 36 h. Fresh rested fillets were obtained by anesthesia with AQUI-S™. They had high cut surface pHs (7.63) and high concentrations of adenosine triphosphate (ATP) and creatine phosphate (3.75 and 8.73 μmol g⁻¹ respectively), which depleted over 12 h. In contrast, fresh exhausted fillets had low cut surface pHs (6.66) and ATP and creatine phosphate were depleted. Adenosine diphosphate (ADP) and β-nicotinamide adenine dinucleotide (NAD⁺) concentrations also remained significantly higher during the first 12 h of storage in rested fillets. In fresh rested fillets inosine monophosphate (IMP) concentrations reached maximum after 12 h storage (4.78 μmol g⁻¹), whereas maximum IMP concentrations occurred immediately postharvest in the exhausted fillets (6.42 μmol g⁻¹). After 36 h storage, K-values in exhausted fillets reached 52.11% compared to 19.27% in rested fillets. Rested harvesting of Chinook salmon improved the fillets’ metabolic potential postharvest, extending metabolite depletion times, changing IMP concentrations and reducing K-values. Practical Application: This study shows that an improved metabolic potential is maintained in salmon fillets from fish harvested in a rested state (that is, with no stress and exhaustion) using an isoeugenol based anesthetic (AQUI-S™). Improved understanding of postharvest metabolic function may help to improve quality and storage properties of high value fish tissues.     

Aerobic Counts, Color and Adenine Nucleotide Changes in CO2 Packed Refrigerated Striped Bass Strips

Hybrid striped bass (HSB) strips were dipped in chlorine or distilled water and packaged in 60% CO₂, 6% O₂, and 34% N₂ (MAP) or in AIR. APC reached 10⁸ CFU/g after 4 days for AIR and 10 days for MAP fish. Sensory panelists detected a whiter color flesh in fish treated with chlorine. Hypoxanthine increased while IMP decreased and ADP and ATP did not change throughout. If inosine was excluded in the predictor, a modified K value (K*) could be applicable as a freshness indicator of freshwater HSB but storage environment should be specified. K* values correlated highly with APC for AIR (R²= 0.84) and MAP packs (R²= 0.85).     

Freshness assessment of gilthead sea bream (Sparus aurata) by machine vision based on gill and eye color changes

The fish freshness was evaluated using machine vision technique through color changes of eyes and gills of farmed and wild gilthead sea bream (Sparus aurata), being employed lightness (L^*), redness (a^*), yellowness (b^*), chroma (c^*), and total color difference (ΔE) parameters during fish ice storage. A digital color imaging system, calibrated to provide accurate CIELAB color measurements, was employed to record the visual characteristics of eyes and gills. The region of interest was automatically selected using a computer program developed in MATLAB software. L^*, b^*, and ΔE of eyes increased with storage time, while c^* decreased. The a^* parameter of fish eyes did not show clear a trend with storage time. The L^*, b^*, and ΔE of fish gills increased with storage time, but a^* and c^* decreased. Regression analysis and artificial neural networks approaches were used to correlate the eyes and gills color parameters with the time of storage and a strong correlation was found between color parameters and storage day. Gills color changes were more precise than those found for eyes in order to evaluate the fish freshness. However, the gills cover should be removed for taking the images and thus, the method is destructive and time-consuming. Therefore, the color parameters of fish eyes can be used as a green, low cost and easy method for fast and on-line assessing of fish freshness in food industry.     

A non-destructive ammonium detection method as indicator for freshness for packed fish: Application on cod

This paper introduces a non-destructive method for monitoring headspace ammonium as an indicator for changes in the freshness status of packed fish. Electrodes in an aqueous phase in the package monitor changes in the concentration of ammonia produced in/on the packed fish and released in the headspace. The outputs of an ammonium ion-selective electrode (NH₄⁺-ISE) were compared with the volatile amines content of the fish fillets. The method was tested in triplicate with fresh cod fillets stored between −0.5 and 1.9 °C. Changes in the ammonia content of the fish could be monitored in the aqueous phase with the NH₄⁺-ISE. The changes in the NH₄⁺-ISE signal correlated with the content of volatile amines (TVB-N) in the cod fillets. This non-destructive method might be the basis for the development of an intelligent packaging for monitoring freshness of packed fish.     

Recent Advances in Methods and Techniques for Freshness Quality Determination and Evaluation of Fish and Fish Fillets: A Review

The freshness quality of fish plays an important role in human health and the acceptance of consumers as well as in international fishery trade. Recently, with food safety becoming a critical issue of great concern in the world, determination and evaluation of fish freshness is much more significant in research and development. This review renovates and concentrates recent advances of evaluating methods for fish freshness as affected by preharvest and postharvest factors and highlights the determination methods for fish freshness including sensory evaluation, microbial inspection, chemical measurements of moisture content, volatile compounds, protein changes, lipid oxidation, and adenosine triphosphate (ATP) decomposition (K value), physical measurements, and foreign material contamination detection. Moreover, the advantages and disadvantages of these methods and techniques are compared and discussed and some viewpoints about the current work and future trends are also presented.     

CHANGES IN FRESHNESS OF CHILIPEPPER ROCKFISH (SEBASTES GOODEI) DURING STORAGE AS MEASURED BY CHEMICAL SENSORS AND BIOSENSORS

ABSTRACT Trimethylamine (TMA) and ammonia contents in Chilipepper rockfishes were determined by ion specific electrodes, as a late indicator of fish freshness. After 9 days of storage in ice, TMA contents significantly increased, indicating that bacterial spoilage was in progress. The pattern of changes in ammonia contents was similar to that of TMA. Determination of ATP degradation products in Chilipepper rockfish by HPLC showed that AMP and hypoxanthine levels were low and did not change much during storage. The concentration of IMP initially increased and then continuously decreased as inosine accumulated. Only trace amounts of hypoxanthine were detected in rockfish tissues. Chilipepper rockfish appears to differ from other Sebastes species in that ATP degradation results in inosine accumulation rather than hypoxanthine.     

草鱼冷藏期间ATP关联物含量及新鲜度变化

目的：分析草鱼冷藏期间腺嘌呤核苷三磷酸关联物含量的变化,研究草鱼肉中各核苷酸的含量与其新鲜度的相关性。方法：利用强碱将不稳定的核苷酸关联物反应生成其钠盐形式,通过高效液相色谱法检测核苷酸含量,并通过总挥发性盐基氮含量和感官性状的变化进行鲜度评价。结果：生成钠盐形式的腺嘌呤核苷三磷酸关联物能通过色谱很好地分离。新鲜鱼肉中含有高含量的肌苷酸,达504.34 mg/kg。冷藏2 d内草鱼腺嘌呤核苷三磷酸、肌苷酸含量快速下降,次黄嘌呤含量则迅速增加。冷藏后腺嘌呤核苷三磷酸未检出,肌苷酸下降幅度达92.77%,次黄嘌呤增加幅度达89.82%。冷藏期间挥发性盐基氮含量一直上升,冷藏6 d后超出最大值限度,冷藏草鱼的贮藏期限为6 d。     

Prolonging Shelf-Life of Carp by Combined Ionising Radiation and Refrigeration

Experiments were performed using ionisating radiation in order to prolong the shelf-life of two groups of refrigerated fish ( Cyprinus carpio ). After irradiation fish were kept at 0–2°C. Non-irradiated fish reached the non-acceptability point in 16 days and irradiated fish reached that point in 31 days. No difference was found between shelf-life of whole or eviscerated fish. If fish were immediately cooled to 0°C after death, their shelf-life was prolonged considerably. From this study it is clear that chemical tests of freshness such as TVB-N and K value determination are not appropriate for the study of irradiated fish. Organoleptic estimations and a new determination using an odour concentration meter seem to fit best the objective determination of freshness.     

Postmortem changes in cazon fish muscle stored on ice

The biochemical, chemical and physical postmortem changes and their relation to the cazon muscle eating quality were studied during an 18 day storage period at 0 °C (ice). Content of ATP and breakdown products, K value, pH, trimethylamine (TMA-N), total volatile bases (TVB-N), water-holding capacity (WHC), colour and texture changes were examined. At the beginning of the study, the cazon muscle showed a low concentration of ATP and a high value of IMP. Regarding to the signs of freshness and deterioration, K value presented a linear increase (r² = 0.97) with an initial value of 1.05% and a final value of 58.9%. The TBV-N and TMA-N significantly increased (P < 0.05). As for the physical analysis whereas the pH and the WHC changed (P < 0.05); texture was not affected (P < 0.05). The overall results of this study indicated that the edible quality of cazon fish muscle was maintained during at least 18 days of ice storage.     

A nondestructive method for estimating freshness of freshwater fish

The traditional indictors of fish freshness including total aerobic count (TAC), K value, total volatile basic nitrogen (TVB-N), and sensory assessment (SA) were measured regularly to analyze the freshness changes during chill storage. Electric conduction property of whole fish was also studied by measuring their impedances under different frequencies as a fast nondestructive method. The relationship between traditional freshness indictors and electric conductivity was analyzed to determine the feasibility of evaluating fish freshness based on impedance change ratio (Q value) during storage. The results showed that traditional freshness indictors (TAC, K value, and TVB-N) values increased as storage time prolonged, while Q value and SA decreased. There were good relationships between Q value and TAC, K value, TVB-N, and SA (P < 0.01), with the correlation coefficients were 0.943, 0.996, 0.951, and 0.968, respectively. Thus, Q value can be used as a valid index for freshness evaluation and this method via measuring the electric conductivity property of whole fish is a fast nondestructive method for determining the freshness of fish during storage.     

Comparison of selected methods of assessing freshness quality and remaining storage life of iced gilthead sea bream (Sparus aurata)

Quality changes of whole, iced gilthead sea bream were monitored by sensory evaluation, k₁ value, GR Torrymeter, and bacterial counts. The methods were tested for their suitability to determine freshness quality and remaining storage life in ice. Depending on the measured parameter, post-mortem age of the iced fish could be predicted with an accuracy of ±1.5–3.6 days. Although assessment of cooked fish flavour is the underlying basis for establishing the state of the fish, the quality index method can be more effective for routine freshness evaluations. The k₁ value provides a useful means of monitoring early storage change, resulting primarily from autolytic reactions. Counts of sulphide-producing bacteria can be used to determine the time to rejection, while total counts at 20 °C are only poor measures of freshness quality. The GR Torrymeter offers a unique practical tool for assessing freshness quality and remaining storage life of iced gilthead sea bream.     

Establishment of kinetic models based on electrical conductivity and freshness indictors for the forecasting of crucian carp (Carassius carassius) freshness

To study quality changes in cold chain circulation, kinetic models were developed to predict the freshness of crucian carp at different temperatures during storage. Electrical conductivity (EC) and freshness indictors (Total volatile basic nitrogen, Total aerobic count and K-value) at 270, 273, 277, 282 and 288 K were accessed to investigate the relation between the crucian carp’s freshness and storage condition (storage temperature and storage time). The kinetic models were developed based on Arrhenius equation. Activation energies (E_A) of EC and Total aerobic count (TAC) are 97.75 and 105.93 kJ mol⁻¹, and corresponding rate constants (k₀) are 5.25 × 10¹⁶ and 5.70 × 10¹⁸, respectively. Relative errors between predicted and values of EC are all within ±5%. The kinetic model established through EC can accurately describe the changes of crucian carp’s quality during the storage within 270-288 K. The kinetic model established based on TAC can accurately forecast crucian carp’s early freshness.     

Protective effect of ω-3 polyunsaturated fatty acids (PUFA) on sodium nitrite induced nephrotoxicity and oxidative damage in rat kidney

Sodium nitrite (SNT) widely used as a curative agent in meat processing industry possesses cell-transforming mutagenic and cytogenic properties. Dietary omega-3 polyunsaturated fatty acids (ω-3 PUFA) has been shown to reduce the severity of certain types of cancers, cardiovascular and renal diseases. The present study examined whether feeding of fish oil (FO)/flaxseed oil (FXO) has protective effect against SNT-induced toxicity. SNT significantly altered the activities of serum creatinine (Crt), blood urea nitrogen (BUN), metabolic and brush border membrane (BBM) enzymes. SNT caused significant imbalances in the antioxidant system associated with increased lipid peroxidation (LPO). Feeding of FO and FXO with SNT ameliorated the changes in various parameters caused by SNT. Nephrotoxicity parameters lowered and enzyme activities of carbohydrate metabolism, BBM and radioactively labeled inorganic phosphate (³²Pi) transport were improved to near control values. The results of the present study suggest that ω-3 PUFA-enriched FO and FXO from sea-foods and plant sources respectively are similarly effective in reducing SNT-induced nephrotoxicity and oxidative damage.     

水产品中ATP及其关联化合物研究进展

三磷酸腺苷(ATP)降解是水产品死后肌肉中发生的重要生化反应之一,ATP的降解程度不仅可以作为表征鱼类鲜活程度的重要指标,而且对水产品的风味也有影响。本文对水产品中ATP及其关联化合物的代谢机制、与鲜度及风味的关联及检测方法进行了全面综述,并分析了其在水产品贮藏及加工过程中的含量变化,旨在对优化水产品贮藏及加工条件提供借鉴意义,以满足消费者对水产品鲜度及品质日益增长的需求。     

Evaluation of a freshness indicator for quality of fish products during storage

A freshness indicator consisting of a polymer matrix solution containing the pH-sensitive dye bromocresol green was investigated for monitoring visible color changes of fish spoilage volatile compounds based on the quantity of volatile amines. Mackerel fillets were inoculated with Pseudomonas fragi and stored in incubators at 5, 12, 18, and 25°C. Chromaticity values of the freshness indicator accurately tracked an increase in the trimethylamine content in the packaging headspace. Gradual color changes of the freshness indicator response correlated with the quality of fish, including growth of P. fragi and pH values during storage. Results will be useful to establish a basis for development of a freshness indicator and to determine the suitability of freshness indicator formulations for intelligent food packaging applications.     

Technical note: Fourier transform infrared spectral analysis in tandem with 31P nuclear magnetic resonance spectroscopy elaborates detailed insights into phosphate partitioning during skimmed milk microfiltration and diafiltration

Our previous study identified peaks in the ³¹P nuclear magnetic resonance (³¹P NMR) spectra of skim milk, denoting the interaction of different phosphate species such as inorganic and casein-associated phosphate during the separation of colloidal and serum phases of skim milk by microfiltration (MF) and diafiltration (DF). In the current study, we investigated the same samples generated by the aforementioned separation using attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy analysis. The results confirmed that the technique was not only capable of differentiating between the mineral equilibrium of the casein phosphate nanocluster (CPN) and milk serum, but also complemented the application of ³¹P NMR. An ATR-FTIR broad band in the region of 1,055 to 1,036 cm^?1 and a specific band at 1,076 cm^?1 were identified as sensitive to the repartitioning of different phosphate species in milk in accordance with the ³¹P NMR signals representing casein-associated phosphate and inorganic phosphate in the serum. A third ATR-FTIR signal at 1,034 cm^?1 in milk, representing precipitated inorganic calcium phosphate, had not previously been detected by ³¹P NMR. Thus, the results indicate that a combination of ATR-FTIR and ³¹P NMR spectroscopies may be optimally used to follow mineral and protein phase changes in milk during membrane processing.     

Energy Catabolism in Rabbit Muscle as Affected by Brine Injection: 31P NMR Studies

The energy catabolism in brine-injected muscles was examined by ³¹P Nuclear Magnetic Resonance (NMR) spectroscopy. Immediately after death of rabbits, brines containing NaCl, with or without pyrophosphate, were injected into the arterial system. ³¹P NMR spectra at 4°revealed marked heterogeneity in postmortem catabolism due to brine diffusion. The heterogeneity of the Pi signal for injected muscles reflected the existence of muscle areas with different intracellular pH values. This observation suggested an increase in rate of glycolysis for fibers experiencing brine. The heterogeneity of brine diffusion seemed to be affected by method of injection.     

Freshness assessment of ray fish stored in ice by biochemical,chemical and physical methods

Ray fish were caught, filleted, and stored in ice. Fillets were analysed for 18 days to determine the chemical, biochemical and physical changes and their relation to the muscle eating quality. Trimethylamine (TMA-N), total volatile bases (TVB-N), ATP content and breakdown products, K value, pH, texture, water-holding capacity (WHC) and colour changes were monitored. At the beginning of the study, the ray fish muscle showed a low concentration of ATP and a high value of inosine 5′-monophosphate (IMP). Regarding to the signs of freshness and deterioration, K value presented an exponential increase (r2 = 0.95) with an initial value of 4.7% and a final value of 47.5%. Furthermore, the TBV-N and TMA-N significantly increased (P < 0.05) during the storage in ice. As for the physical analysis whereas the texture changed (P < 0.05); pH and the WHC were not affected (P < 0.05). The overall results of this study indicated that the edible quality of ray fish muscle was maintained during at least 15 days of ice storage.     

Effects of freshness on ATP-related compounds in retorted chub mackerel Scomber japonicus

To examine the usefulness of measurement of adenosine triphosphate (ATP)-related compounds for estimation of the quality of canned and/or retorted fishes, we investigated the ATP-related compounds, in sashimi (for raw-eating)-grade and for-cooking-grade chub mackerel Scomber japonicus before and after retort process (121 °C for 30 min) by HPLC method. By the deterioration (storage time) and retort process, inosine monophosphate (IMP), an umami-taste compound, was decreased and inosine (HxR), hypoxantine (Hx) and the K-value, an index of fish freshness defined as the ratio of the sum of HxR and Hx to the sum of ATP-related compounds, were increased. By the retorting, the K-values of sashimi-grade, for-cooking-grade and unacceptable-grade meats were increased from 9.9%, 26.6% and 70% to 36%, 46% and 81%, respectively. These results suggest that the measurement of ATP-related compounds in retorted fish products may estimate the freshness in raw materials, the product quality and/or the good manufacture practices.