CHANGES IN CONTENT OF OCTOPINE, ACIDIC OPINES, RELATED AMINO ACIDS AND PHOSPHOARGININE IN THE ADDUCTOR MUSCLE OF THREE SPECIES OF SCALLOP DURING STORAGE

The postmortem changes of octopine (Oct), strombine (Stn), tauropine (Trn), alanopine (Aln), related amino acids and phosphoarginine (PA) in the edible adductor muscles of Chlamys nobilis, Pecten albicans and Patinopecten yessoensis during storage at 0 and 5C were examined. For this purpose, new alternative HPLC methods for the analysis of octopine and acidic opines were developed. Among opines, Oct was the major postmortem glycolytic end product of all three scallops, followed by Stn, Trn and Aln, respectively. The accumulation of Oct during storage at 0 and 5C was similar. On the contrary, almost twice as much Stn accumulated when stored at 5C compared to 0C. Trn and Aln increased to a lesser extent. Arginine and PA decreased, while glycine, taurine and alanine increased during storage.     

Effects of Rigor Status during High‐Pressure Processing on the Physical Qualities of Farm‐Raised Abalone (Haliotis rufescens)

High‐pressure processing (HPP) is used to increase meat safety and shelf‐life, with conflicting quality effects depending on rigor status during HPP. In the seafood industry, HPP is used to shuck and pasteurize oysters, but its use on abalones has only been minimally evaluated and the effect of rigor status during HPP on abalone quality has not been reported. Farm‐raised abalones (Haliotis rufescens) were divided into 12 HPP treatments and 1 unprocessed control treatment. Treatments were processed pre‐rigor or post‐rigor at 2 pressures (100 and 300 MPa) and 3 processing times (1, 3, and 5 min). The control was analyzed post‐rigor. Uniform plugs were cut from adductor and foot meat for texture profile analysis, shear force, and color analysis. Subsamples were used for scanning electron microscopy of muscle ultrastructure. Texture profile analysis revealed that post‐rigor processed abalone was significantly (P < 0.05) less firm and chewy than pre‐rigor processed irrespective of muscle type, processing time, or pressure. L values increased with pressure to 68.9 at 300 MPa for pre‐rigor processed foot, 73.8 for post‐rigor processed foot, 90.9 for pre‐rigor processed adductor, and 89.0 for post‐rigor processed adductor. Scanning electron microscopy images showed fraying of collagen fibers in processed adductor, but did not show pressure‐induced compaction of the foot myofibrils. Post‐rigor processed abalone meat was more tender than pre‐rigor processed meat, and post‐rigor processed foot meat was lighter in color than pre‐rigor processed foot meat, suggesting that waiting for rigor to resolve prior to processing abalones may improve consumer perceptions of quality and market value.     

Effect of high pressure processing on the physicochemical and sensorial properties of scallop (Mizuhopecten yessoensis) during iced storage

Scallops are the third largest aquaculture mollusks product, while they are highly perishable during storage. The main purpose of the present study was to evaluate the effect of high pressure processing (HPP) on physicochemical and sensorial properties of scallop (Mizuhopecten yessoensis) during refrigeration storage. The scallop adductor muscle was treated with different pressures (200, 300, 400 and 500 MPa, 5 min) and iced storage for 28 days. Results showed that HPP delayed microbial growth as pressure increased. HPP (≥400 MPa) resulted in myosin and actin denaturation, increased hardness, whiteness, pH and promoted water migration. However, preliminary sensory analysis showed no significant difference between pressure-treated and control adductor muscles in appearance, odour, texture and overall acceptability after cooking. In addition, pressure-treated adductor muscles (≥300 MPa) remained edible after 28 days of storage. Overall, these results can provide basic knowledge for the storage of pressure-treated scallop meat.     

NUCLEOTIDE CATABOLISM IN COLD STORED ADDUCTOR MUSCLE OF SCALLOP (ZYGOCHLAMYS PATAGONICA)

The postmortem catabolism of adenosine triphosphate (ATP) in cold stored scallop adductor muscles was examined. The change In the pH of stored muscles was also investigated. The ATP content increased for a short time after death and afterwards decreased up to 24 h of storage. Thereafter, the nucleotide level remained unchanged up to 120 h of storage. The ADP content slightly decreased up to 48 h and after that remained unchanged. The AMP slowly accumulated to around 15% of the total nucleotide concentration when the ATP decreased. Small amounts of IMP were detected in all samples. Conversely, adenosine (Ado) was not detected. Inosine (HxR) slightly increased after 48 h of storage and hypoxanthine (Hx.) significantly increased after 24 h. The 260/250‐absorbance ratio of muscle extracts and the pH of stored muscles fell sharply up to 24 h and then decreased slowly. The Hx contents were positively correlated (P < 0.01) with both the Hx/AMP ratios and the K values.     

Heat-Induced Tendering of Turban Shell (Batillus cornutus) Muscle

The foot, opercular and visceral muscles were excised from the turban shell Batillus cornutus, and their heat-induced changes in toughness and ultrastructure were compared. When heated up to 30°C, the toughness of foot muscle decreased in the upper and middle regions, but increased in the lower region. The toughness of these three regions decreased at temperatures between 50-70°C, where collagen might be denatured. Some changes in toughness were also observed in the opercular muscle by heating up to 30°C, whereas the toughness of visceral muscle remained unchanged over a wide range of temperature. Transmission electron microscopy showed that the intrinsic structure of collagen fibrils in each muscle was lost at 60°C, with partial swelling.     

BIOCHEMICAL PROPERTIES OF ACTOMYOSIN AND EXPRESSIBLE MOISTURE OF FROZEN STORED ADDUCTOR MUSCLES OF PATAGONIAN SCALLOP (ZYGOCHLAMYS PATAGONICA)

The biochemical properties of actomyosin and the expressible moisture of frozen stored adductor muscles of scallop (Zygochlamys patagonica) were investigated. After freezing (zero time of storage) both the enzymatic activity and the reduced viscosity of actomyosin remained unchanged with respect to those corresponding to actomyosin from unfrozen muscles. Both parameters significantly decreased (P < 0.01) at 4 months of frozen storage and thereafter gradually decreased. No significant differences (P > 0.01) were observed in the relative percentages of myosin, actin, and in the myosin/actin ratio up to 4 months of storage. Thereafter myosin significantly decreased (P < 0.01) up to the end of storage. The decrease in the biochemical properties of actomyosin was accompanied by a loss in the water holding capacity of the muscles.     

The effects of mixing,transport and duration of lairage on carcass characteristics in commercial bacon weight pigs

On arrival at the factory commercial crossbred pigs were subjected to various treatments: (i) penned in producer lots; (ii) mixed with pigs from another producer and (iii) mixed and subjected to an additional transport of 1-1.5h duration. Groups of pigs were killed on the day of arrival or after overnight lairage. Carcass parameters including pH₁ (pH 45 min post mortem) and pH_u (pH 20 h post mortem) values of the Longissimus dorsi (LD) and adductor muscles were taken post mortem. Mixing and transport had no statistically significant effect on any of the carcass parameters measured, although overnight lairage resulted in significant decreases in hot carcass weight, killing-out percentage and liver weight. The incidence of carcasses classified as pale soft and exudative [PSE (muscles with a pH₁ of 5.9 or less)] or dark firm dry [DFD (muscles with a pH_u of 6.2 or greater)] was high after both normal and overnight lairage. pH₁ and pH_u values of the LD and adductor muscles were not significantly affected by mixing or transport. Statistically significant differences in the incidence of DFD between treatment groups were observed. In general the incidence of DFD increased more after overnight lairage in pigs penned in producer lots, than in pigs penned in mixed producer lots.     

D-lactate-selective amperometric biosensor based on the mitochondrial fraction of Ogataea polymorpha recombinant cells

During the recent decades, a lot of data about the significance of D-lactate determination in food technology and quality control have been accumulated. Nowadays, the development of new methods for the determination of D-lactate is very relevant, especially with regard to biosensors. To construct a D-lactate-selective biosensor, we suggest using the mitochondria of recombinant yeast cells of Ogataea (Hansenula) polymorpha “tr6” (gcr1 catX/Δcyb2, prAOX_DLDH) overproducing D-lactate: cytochrome c-oxidoreductase (DLDH, EC 1.1.2.4) and lacking an L-lactate-specific enzyme (flavocytochrome b₂, E.C. 1.1.2.3). The usage of the pure enzyme is problematic due to the complexity of its isolation and stabilization because of the intramembranous localization of DLDH. The enzyme catalyzes D-lactate oxidation to pyruvate coupled with ferricytochrome c reduction to ferrocytochrome c. The constructed biosensor is characterized by high sensitivity (18.5 А·М⁻¹·m⁻²), a low detection limit (3 μM of D-lactate), wide linear ranges, good selectivity, and sufficient stability. The real samples' analysis of D-lactate in dairy products was performed, and high correlation of the obtained results with the reference approach (0.7 < r < 1) and literature data was demonstrated.     

Preparation and application of a flaxseed meal protein film containing lemongrass (Cymbopogon citratus) oil

Flaxseed meal protein (FMP) films were prepared, and their mechanical properties (tensile strength (TS) and elongation at break (E) values), water vapour permeability, optical properties and thermogravimetric analysis were evaluated. Briefly, 5 g FMP, 2 g fructose and 0.03 g ferulic acid were required for the optimal preparation of an FMP film. The TS and E values of the FMP film were 13.12 MPa and 61.90%, respectively. Furthermore, different amounts of lemongrass oil (LE) were incorporated into the FMP film to prepare an antimicrobial film. Wrapping pen shell adductor muscle with the FMP film containing 1.0% LE reduced the counts of inoculated Listeria monocytogenes and Escherichia coli O157:H7 compared with those in the control, after storage at 4 °C for 12 day. Consequently, packaging with FMP film containing 1.0% LE can be useful in improving the quality of pen shell adductor muscle during storage.     

Fast identification of scallop adductor muscles using species-specific microsatellite markers

Scallop adductor muscles are very popular delicious seafood distributed in the international markets. Identification of commercial adductor muscles to the species level is an important issue to assure the correct labeling for their distribution. In the present study, we established the species-specific microsatellite markers for four main economic scallop species to identify commercial adductor muscles. A total of 140 adductors derived from three different food processes, the frozen, the dried and the canned, were collected from markets and analyzed using the species-specific microsatellite markers. Although the DNA extracted from the commercial samples was highly degraded, all samples were well identified using the method established in the present study. This method well demonstrated high precision and high sensitivity, and more competence in the identification of mixed commercial samples. Moreover, the results in this study gave the experimental evidences for the potential use of species-specific microsatellite markers for species identification in the market management.     

Antioxidant activity of hydrolysates obtained from scallop (Patinopecten yessoensis) and abalone (Haliotis discus hannai Ino) muscle

Scallop (Patinopecten yessoensis) and abalone (Haliotis discus hannai Ino) muscle were hydrolysed with commercially available food-grade proteases. The resulting hydrolysates showed DPPH and hydroxyl radicals scavenging abilities, reducing power, and ferrous ion chelating capacity. The antioxidant activities of hydrolysate of abalone foot muscle (HAFM) increased with increasing incubation time during the whole hydrolysis process in 180 min. Whereas, the antioxidant activities of hydrolysate of scallop adductor muscle (HSAM) increased at initial stage and peaked after 25-30 min of hydrolysis, and then gradually decreased thereafter. Compared with HAFM, HSAM with comparable hydrolysis time contained more free amino acids (FAA) and small-sized peptides (below 500 Da), which may account for the differences in antioxidant activities versus hydrolysis time curves of the two hydrolysates. The above results indicate that limited hydrolysis of proteins can increase their antioxidant activity, whereas extensive hydrolysis can decrease it.     

海州湾养殖文蛤体内不同组织的重金属富集特性及其食用安全评价

测定海州湾养殖池塘成体文蛤体内肝胰腺、鳃、外套膜、足和闭壳肌5 个干质量组织中Cd、Cr、Pb、Ni、Cu 和Zn 这6 种重金属的含量。结果表明文蛤5 组织中闭壳肌和肝胰腺是重金属选择性富集的主要器官。Cr、Pb、Ni 在5 种组织中以闭壳肌的含量最高,分别高达58.981、4.298、10.873μg/g,与其余组织均有显著差异(P ＜ 0.05);而Cu 和Zn 则以闭壳肌的含量最低,分别为0.844、58.076μg/g,而肝胰腺中含量最高,分别达17.776、173.147μg/g,差异显著(P ＜ 0.05);相反,Cd 和Ni 则在肝胰腺中含量最低(0.140、4.807μg/g),与其余组织显著差异(P ＜ 0.05)。6 种重金属中,Zn 在5 种组织中的含量最高(173.147~58.076μg/g),Cd 的含量最低(0.140～0.336μg/g),Pb 次之(1.549～4.298μg/g)。文蛤5 组织中闭壳肌是主要的受污染组织,Cr、Ni 和Pb 的污染指数间于1.52～6.40,而足的污染最小,6 种重金属仅Ni 超标,其余污染指数为0.01～0.96;6 种重金属中Ni 的污染最严重,5组织均超标,污染指数P 间于2.77～6.40,而毒性较强的Cd 以及Cu 在5 组织中均未超标。     

Differentiation between Helix and Achatina Snail Meat by Gel Electrophoresis

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and photodensitometry of foot muscle proteins in Helix (Helix pomatia) and Achatina (Achatina fulica) demonstrate a distinctive pattern in the low molecular weight region between the two species examined. Muscle proteins from Helix showed two distinguishing bands of 18,000 and 16,000 daltons, while Achatina showed only a single band (18,000 daltons). This distinguishing feature was also evident when the foot muscles were heated at 120°C for 30 min. It is proposed that the difference in this simple pattern of low molecular weight proteins might be used as a tool to differentiate Helix meat from Achatina meat in raw, frozen, and cooked samples.     

Evidence for differences in post mortem intramuscular phospholipase activity in several muscle types

The neutral and polar lipids of chicken adductor longus and pork semitendinosus muscles have been analysed at several periods of post mortem ageing. A complete fatty acid analysis for pork muscle has also been carried out. The results revealed small changes in chicken leg muscle phosphatidyl ethanolamine and free fatty acid fractions, suggesting limited phospholipase A activity in this muscle. The pork muscle showed no changes. The results are considerably different from results obtained for chicken pectoralis major. The differences are discussed in the light of the structural and biochemical differences between the sarcotubular systems of red and white muscle fibres.     

Saxitoxins and okadaic acid group: accumulation and distribution in invertebrate marine vectors from Southern Chile

Harmful algae blooms (HABs) are the main source of marine toxins in the aquatic environment surrounding the austral fjords in Chile. Huichas Island (Aysén) has an history of HABs spanning more than 30 years, but there is limited investigation of the bioaccumulation of marine toxins in the bivalves and gastropods from the Region of Aysén. In this study, bivalves (Mytilus chilenses, Choromytilus chorus, Aulacomya ater, Gari solida, Tagelus dombeii and Venus antiqua) and carnivorous gastropods (Argobuccinum ranelliformes and Concholepas concholepas) were collected from 28 sites. Researchers analysed the accumulation of STX-group toxins using a LC with a derivatisation post column (LC-PCOX), while lipophilic toxins (OA-group, azapiracids, pectenotoxins and yessotoxins) were analysed using LC-MS/MS with electrospray ionisation (+/–) in visceral (hepatopancreas) and non-visceral tissues (mantle, adductor muscle, gills and foot). Levels of STX-group and OA-group toxins varied among individuals from the same site. Among all tissue samples, the highest concentrations of STX-group toxins were noted in the hepatopancreas in V. antiqua (95 ± 0.1 μg STX-eq 100 g^?1), T. dombeii (148 ± 1.4 μg STX-eq 100 g^?1) and G. solida (3232 ± 5.2 μg STX-eq 100 g^?1; p < 0.05); in the adductor muscle in M. chilensis (2495 ± 6.4 μg STX-eq 100 g^?1; p < 0.05) and in the foot in C. concholepas (81 ± 0.7 μg STX-eq 100 g^?1) and T. dombeii (114 ± 1.2 μg STX-eq 100 g^?1). The highest variability of toxins was detected in G. solida, where high levels of carbamate derivatives were identified (GTXs, neoSTX and STX). In addition to the detected hydrophilic toxins, OA-group toxins were detected (OA and DTX-1) with an average ratio of ≈1:1. The highest levels of OA-group toxins were in the foot of C. concholepas, with levels of 400.3 ± 3.6 μg OA eq kg^?1 (p < 0.05) and with a toxic profile composed of 90% OA. A wide range of OA-group toxins was detected in M. chilensis with a toxicity < 80 μg OA eq kg^?1, but with 74% of those toxins detected in the adductor muscle. In all evaluated species, there was no detection of lipophilic toxins associated with biotransformation in molluscs and carnivorous gastropods. In addition, the STX-group and OA-group toxin concentrations in shellfish was not associated with the presence of HAB. The ranking of toxin concentration in the tissues of most species was: digestive glands > mantle > adductor muscle for the STX-group toxins and foot > digestive gland for the OA-group toxins. These results gave a better understanding of the variability and compartmentalisation of STX-group and OA-group toxins in different bivalve and gastropod species from the south of Chile, and the analyses determined that tissues could play an important role in the biotransformation of STX-group toxins and the retention of OA-group toxins.     

The chemical composition of different edible locations (central and edge muscles) of flat fish (Lepidorhombus whiffiagonis)

The chemical composition of the different edible locations (central and edge muscles) of a flat fish (megrim, Lepidorhombus whiffiagonis) was comparatively analysed at both body sides. Higher moisture and lower lipid contents were obtained in central muscles than in edge ones. Edge sites showed higher triacylglycerols and sterols contents and lower mean phospholipids values than central muscles. A higher α‐tocopherol presence was observed in the lipid fraction of central muscles than in the edge ones. For both fish sides, fatty acid (FA) analysis showed lower monounsaturated FA and higher polyunsaturated FA contents and ω3/ω6 ratios in central muscles. Presence of essential elements (Co, Cu, Mn, Se, Zn) did not provide differences among sites considered. Concerning toxic elements, As content showed greater levels in central muscles than in their corresponding edge sites for both fish sides, upper zones showed higher mean scores in As, Cd, Cr, Hg, Ni, Pb and V.     

A novel flavin adenine dinucleotide (FAD) containing d-lactate dehydrogenase from the thermoacidophilic crenarchaeota Sulfolobus tokodaii strain 7: purification, characterization and expression in Escherichia coli

Dye-linked D-lactate dehydrogenase activity was found in the crude extract of a continental thermoacidophilic crenarchaeota, Sulfolobus tokodaii strain 7, and was purified 375-fold through four sequential chromatography steps. With a molecular mass of about 93 kDa, this enzyme was a homodimer comprised of identical subunits with molecular masses of about 48 kDa. The enzyme retained its full activity after incubation at 80 degrees C for 10 min and after incubation at pHs ranging from 6.5 to 10.0 for 30 min at 50 degrees C. The preferred substrate for this enzyme was D-lactate, with 2,6-dichloroindophenol serving as the electron acceptor. Using high-performance liquid chromatography (HPLC), the enzyme's prosthetic group was determined to be flavin adenine dinucleotide (FAD). Its N-terminal amino acid sequence was MLEGIEYSQGEEREDFVGFKIKPKI. Using that sequence and previously reported genome information, the gene encoding the enzyme (ST0649) was identified. It was subsequently cloned and expressed in Escherichia coli and found to encode a polypeptide of 440 amino acids with a calculated molecular weight of 49,715. The amino acid sequence of this dye-linked D-lactate dehydrogenase showed higher homology (39% identity) with that of a glycolate oxidase subunit homologue from Archaeoglobus fulgidus, but less similarity (32% identity) to D-lactate dehydrogenase from A. fulgidus. Taken together, our findings indicate that the dye-linked D-lactate dehydrogenase from S. tokodaii is a novel type of FAD containing D-lactate dehydrogenase.     

FUNCTIONAL, MICROBIAL AND SENSORY CHANGES IN ICE-STORED SEA SCALLOPS (PLACOPECTEN MAGELLANICUS) TREATED WITH SODIUM TRIPOLYPHOSPHATE

Sea scallop adductor muscles were given six processing treatments involving water, phosphate and NaCl. They were evaluated during iced storage for changes in moisture content, aerobic plate count, pH, drip loss, cook loss, and sensory freshness attributes. All treated scallops and a wash control were above the 80% moisture interim federal compliance level. A dip in 10% sodium tripolyphosphate generally produced the least drip and cook losses and lowest aerobic plate counts during iced storage compared to freshwater washed scallops. No additional benefit was derived by very long exposure to solutions of sodium tripolyphosphate.     

Measurement of Veal Color by Fiber Optic Spectrophotometry

Fiber optic spectrophotometry was used to measure the color of pectoralis profundus, diaphragm, transversus abdominis and adductor muscles in the carcasses of nine veal calves raised commercially for the production of white veal. Blood hemoglobin levels measured before slaughter were correlated with absorbance in the transversus at 1 hr postmortem (r = 0.72, P < 0.05 at 540 nm), but this relationship was obscured by 24 hr postmortem. Pectoralis, diaphragm and adductor increased in paleness between 1 hr and 24 hr postmortem (P < 0.01) as muscle pH declined. In the adductor at 24 hr, pH was correlated (P < 0.01) with absorbance at 10 nm intervals ranging from r = 0.75 at 580 nm to r = 0.91 at 700 nm. The effects of postmortem changes in pH should be taken into account when measuring the paleness of veal.     

A Comparison of Some Properties of Beef and Buffalo (Bubalus bubalis) Meat

Assessments were made of the meat properties of four muscles of differing connective tissue content, from both Achilles tendon-hung and tenderstretched (suspended from the sacrosciatic ligament) sides of buffalo (Bubalus bubalis) and Brahman–cross steers of similar mean age (51 months) and carcass weight (ca 230 kg). Color measurements indicated that muscles from buffalo were darker although ultimate pH values of the groups did not differ. Adhesion, compression, and Warner-Bratzler peak shear force minus initial yield force values were significantly greater in buffalo than in beef muscles; indicating greater connective tissue contribution to toughness of buffalo meat. Taste panel assessment of muscles of relatively low connective tissue content in beef, indicated that generic differences in tenderness were slight although buffalo meat was less juicy than beef. Flavor and overall acceptability of buffalo meat were significantly less than for beef.