Clam Meat Research Articles

Taste Compounds and Biofunctional Activities of the Sandy Beach Clam Hydrolysate for the Shellfish Flavoring Condiment

ABSTRACTSandy beach clam meat was hydrolyzed with proteases (Alcalase and Flavozyme) for the manufacture of a natural flavoring condiment. The optimal conditions for the enzymatic hydrolysis of the shellfish meat via the response surface methodology were: temperature, 54.7°C; pH, 5.9; time, 45 h. The total amino acid content of the shellfish hydrolysate was 9,218.8 mg/100 g and consisted mainly of glutamic acid, aspartic acid, glycine, arginine, lysine, and leucine. Nucleotides and their related compounds of the shellfish hydrolysate consisted mainly of adenosine diphosphate (0.86 mg/100 g), adenosine monophosphate (11.24 mg/100 g), and inosine (49.03 mg/100 g). The shellfish hydrolysate resulted in three protein peaks in the Bio-Rad P2 gel chromatography pattern. The antioxidant activity was highest at Peak 1 (64.67%), followed by Peak 2 (27.48%) and Peak 3 (16.67%); whereas the angiotensin I-converting enzyme inhibitory activity was highest at Peak 3 (67.27%), followed by Peak 2 (6.14%). Antitumor activity was highest at Peak 1 (18.77%), followed by Peak 2 (8.75%). All the sensory attributes of the shellfish condiment were scored highly. Therefore, the sand beach clam hydrolysate can be commercialized as an ingredient of a natural flavoring condiment or seasoning.

Complete larval development of Thenus unimaculatus Burton & Davie, 2007 (Decapoda, Scyllaridae)

Larval development of the shovel-nosed lobster Thenus unimaculatus Burton & Davie, 2007 is described based on laboratory studies. The larval stages included four stages of phyllosoma (I-IV), followed by a post larval, non-feeding nisto stage which metamorphosed to the juvenile stage, also known as first seed. The nisto stage is reached in 26-30 days, the average duration of each phyllosoma (I-IV) and nisto was 7, 5, 7, 7 and 4 days, respectively. The phyllosomas are characteristically flattened, leaf-like, transparent planktonic larvae, while the nisto, translucent in appearance, remains sedentary at the bottom. The first juvenile stage has a hard exoskeleton and feeds on fresh clam meat. The survival rate from phyllosoma I to nisto was 22%.

Captive Breeding and Hatchery Production of Mouth Brooding Jewel Cardinal Perch, Pterapogon Kauderni, (Koumanns, 1933) Using Brackish Water: The Role of Live Prey and Green Water Enrichment in Juvenile Production

An attempt was made to study the captive breeding and larval rearing of the Cardinal fish Pterapogon kauderni using brackish water for the first time in India. P. kauderni, a mouth brooder fish was procured from the traders at the size range of 4-6 cm and acclimatized under captive conditions. Suitable water quality parameters were maintained and standardized. The fish was fed with boiled clam meat, octopus, oyster, squid and trash fish thrice a day. Spawning took place after two months of rearing, in between 10:45-13:00 hrs and hatch out occurred after the sunset. Incubation was in the male’s mouth, which was extended up to 21-23 days and after hatch out, juveniles were separated from the parental tank. The tanks were maintained with optimal physico-chemical conditions as in the parent tanks. Different light intensities and diets were provided for the successful of juveniles rearing. Good survival (58%) was achieved by adopting the photoperiod 24L/0D. the results illustrated that the photoperiod and different diets given to the juveniles influences the physiological performance of the juveniles. SGR, FCR and AGR of juveniles of P. kauderni increased significantly with the increase of the photoperiod (P<0.05). Babies looked like their parents at birth and within a week, they obtained parental coloration. Comparatively higher growth rate was observed, when they were fed with algal enriched artemia than the Poly Unsaturated Fatty Acid (PUFA). Babies reached the marketable size within 45 days. This study deliberately reveals that, breeding and rearing of the marine fish P. kauderni using the estuarine water and also reveals the physiological response of juveniles of P. kauderni to the change of photoperiod and substantiated that photoperiod and different diets influences the juvenile growth, survival and feeding.

Antimicrobial Resistance and Detection of themecA Gene Besides Enterotoxin-Encoding Genes Among Coagulase-Negative Staphylococci Isolated from Clam Meat ofAnomalocardia brasiliana

The marine clam Anomalocardia brasiliana is a candidate as a sentinel animal to monitor the contamination levels of coliforms in shellfish-harvesting areas of Brazil's northeastern region. The aim of the present study was to search enterotoxin-encoding genes plus the mecA gene among coagulase-negative staphylococci (CNS) isolates from shellfish meats of A. brasiliana. The specimen clam (n=48; 40 clams per sample) was collected during low tide in the bay area of Mangue Seco from April through June 2009, and random samples of chilled and frozen shelled clam meat (n=33; 250 g per sample) were obtained from retail shops from January through March 2012. Seventy-nine CNS isolates were identified, including Staphylococcus xylosus, S. cohnii spp. urealyticus, S. sciuri, and S. lentus. A high percentage of isolates resistant to erythromycin (58.5%), penicillin (51.2%), and tetracycline (43.9%), and the fluoroquinolones levofloxacin (39%) and ciprofloxacin (34.1%) were recorded from those environmental samples. Isolates from retail shops were particularly resistant to oxacillin (55.3%) and penicillin (36.8%). All CNS resistant to oxacillin and/or cefoxitin were positive for the presence of the mecA gene, but phenotypically susceptible to vancomycin. Also, the enterotoxin-encoding genes seg and seh were detected through multiplex-polymerase chain reaction in 77.7% and 88.8% of the isolates from environmental samples, versus 90.5% and 100% of the isolates from retail shops, respectively. The data reveal the risk to public health due to consuming raw or undercooked shellfish containing enterotoxigenic plus methicillin-resistant CNS.

Aromatic Components Analysis of HongDao Clam by HS-SPME and GC-MS

s: The paper extracted the flavor components of Hongdao Clam by using HS-SPME Technique and made an analysis of it by GC-MS. It compared the analysis results of 75 μm Carboxen/PDMS microextraction fibers and 100 μm PDMS microextraction fibers, with the result that the later one was suitable for flavour substance analysis of Hongdao Clam. Besides, by comparing the flavor components of Hongdao clam meat and soup, the thesis reached a conclusion that there are eight common ingredients in them, as well as the type and relative percentage composition of the flavor substance. This research provided a reference for the application of combining SPME and GC-MS techniques in aquatic product processing industry.

Climate variability and massive mortalities challenge giant clam conservation and management efforts in French Polynesia atolls

In 2004, the first no-take area (NTA) dedicated to the conservation of giant clams Tridacna maxima was implemented in Tatakoto Atoll, French Polynesia. This NTA protected a unique area worldwide, with extraordinarily high giant clam densities (up to 337 individuals per m2 on 20-m transect). In 2012, a stock assessment survey revealed a dramatic decrease of the clam population. The reduced densities peaked at 38indm−2 and the stock in the NTA decreased from 20.1±6.0million to 1.9±0.55million clams (mean±95% confidence interval). Losses of similar proportions were observed throughout the atoll. Remarkably, the 83% overall loss of this natural resource used daily for consumption and for exports of clam meat to Tahiti Island went unnoticed by the local population. Field clues, including the size of live juveniles attached to the inside of dead shells, pointed to a massive mortality occurring about 3years before the 2012 survey. Examinations of sea surface temperature satellite data identified a high range of temperature variations before March 2009. In agreement with past and recent events in other atolls, this anomaly is the most likely explanation of the massive loss of giant clams in Tatakoto Atoll, although the exact hydrological and biological secondary mechanisms that occurred in the lagoon remain unclear. The consequences of the massive die-off inside and outside the NTA require new long-term management strategies, by reinforcing the top-down national giant clam management arrangements and by setting flexible management objectives across a network of islands.

Cover Caption

On the Cover: Effect of HHP on the appearance and volume of clam meat: clam on left was unprocessed; clam on right was processed at 552 MPa for 3 min, in “Inactivation of Vibrio parahaemolyticus in Hard Clams (Mercanaria mercanaria) by High Hydrostatic Pressure (HHP) and the Effect of HHP on the Physical Characteristics of Hard Clam Meat” by Gabriel K. Mootiam, George E. Flimlin, Mukund V. Karwe, and Donald W. Schaffner; p E254.

Inactivation of Vibrio parahaemolyticus in Hard Clams (Mercanaria mercanaria) by High Hydrostatic Pressure (HHP) and the Effect of HHP on the Physical Characteristics of Hard Clam Meat

Shellfish may internalize dangerous pathogens during filter feeding. Traditional methods of depuration have been found ineffective against certain pathogens. The objective was to explore high hydrostatic pressure (HHP) as an alternative to the traditional depuration process. The effect of HHP on the survival of Vibrio parahaemolyticus in live clams (Mercanaria mercanaria) and the impact of HHP on physical characteristics of clam meat were investigated. Clams were inoculated with up to 7 log CFU/g of a cocktail of V. parahaemolyticus strains via filter feeding. Clams were processed at pressures ranging from 250 to 552 MPa for hold times ranging between 2 and 6 min. Processing conditions of 450 MPa for 4 min and 350 MPa for 6 min reduced the initial concentration of V. parahaemolyticus to a nondetectable level (<10(1) CFU/g), achieving >5 log reductions. The volume of clam meat (processed in shell) increased with negligible change in mass after exposure to pressure at 552 MPa for 3 min, while the drip loss was reduced. Clams processed at 552 MPa were softer compared to those processed at 276 MPa. However, all HHP processed clams were found to be harder compared to unprocessed. The lightness (L*) of the meat increased although the redness (a*) decreased with increasing pressure. Although high pressure-processed clams may pose a significantly lower risk from V. parahaemolyticus, the effect of the accompanied physical changes on the consumer's decision to purchase HHP clams remains to be determined. Shellfish may contain dangerous foodborne pathogens. Traditional methods of removing those pathogen have been found ineffective against certain pathogens. The objective of this research was to determine the effect of high hydrostatic pressure on V. parahaemolyticus in clams. Processing conditions of 450 MPa for 4 min and 350 MPa for 6 min reduced the initial concentration of V. parahaemolyticus to a nondetectable level, achieving >5 log reductions.

Proximate, Amino Acid, Fatty Acid and Mineral Analysis of Clam, Meretrix casta (Chemnitz) from Cuddalore and Parangipettai Coast, South East Coast of India

Proximate, Amino Acid, Fatty Acid and Mineral Analysis of Clam, Meretrix casta (Chemnitz) from Cuddalore and Parangipettai Coast, South East Coast of India The eulamellibranch bivalves, M. casta Chemnitz is an edible mollusc belonging to phylum Mollusca, class Bivalvia and family Veneridae. It is abundantly found in marine and estuarine water bodies at high rates in the local markets of Tamil Nadu along Indian coast. The clam meat is white and sweet and tasty. Whereas most food sources for the humans are provided from marine flora and fauna, now a days clams has been functionally used as another good source of food nutrients to man compared to marine animals. The bivalves are also known to be good sources for the provision of protein, carbohydrate, lipid, amino acids, fatty acids, vitamins and minerals. This study was conducted to assess the nutritional qualities of M. casta of the Cuddalore and Parangipettai in two different coasts.

Effects of Different Liquid Smoke Flavor Levels on the Shelf Life of Venus Clam (Chamelea Gallina , L 1758) Meat

This study investigated the effects of smoke flavoring (SF) on vacuum-packed and chilled Venus clam meat shelf life. The different levels of SF led to different TVB-N (total volatile basic nitrogen), TVC (total viable count), LAB (lactic acid bacteria), pH and sensory evaluations during 30 days of storage (P < 0.05). SF had no effect on moisture, protein, lipid and ash contents of Venus clams during storage. The addition of 200 mL of SF per liter of 4% brine solution was preferred because of its sensory attributes, microbial and chemical characteristics, and 30-day shelf life at refrigerated storage. Practical Applications The present experiment demonstrates that the addition of SF highly affected the shelf life of liquid smoked clams. The maximum shelf life of the LS2 group was determined as 30 days. Our results showed that the addition of 200 mL/L SF to 4% brine solution provided the best results for consumer acceptance, as well as microbial and chemical properties for Venus clam.

Analysis of Condition Index in Polymesoda expansa (Mousson 1849)

The Condition Index (CI) is a method to measure overall health of fish and that has been applied to estimate the effect that different environmental factors have on clam meat quality. The CI of local mangrove clam Polymesoda expansa in Kelulit, Miri Sarawak was determined from October 2010 to November 2011. Condition index that is generally used to characterize the physiological activity of organisms, varied from 1.8% in December 2010 to 3.4% in October 2011, with low values observed during the spawning period. The clam attained their best condition in quality of flesh weight during July-October. In present study, the CI showed a clear relationship with the reproductive cycle of P. expansa. However, no significant correlation (p > 0.05) was found between CI and the different physicochemical parameter of seawater. The data presented is necessary for developing sustainable management strategies and broodstock selection for the species which is crucial in aquaculture development.

Selection of diet for culture of juvenile silver pomfret, Pampus argenteus

Juvenile silver pomfret, Pampus argenteus, was grown in culture tanks for 9 weeks on four different diets, and their effects on fish growth, digestive enzyme activity, and body composition were assessed. The feeding regime was as follows: Diet 1: fish meat; Diet 2: fish meat+artificial feed; Diet 3: fish meat+artificial feed+Agamaki clam meat; Diet 4: fish meat+artificial feed+Agamaki clam+copepods. The greatest weight gain was associated with Diet 4, while the lowest weight gain was associated with Diet 1. No significant difference was observed in weight gain between fish receiving Diet 2 and Diet 3. Specific growth rate followed similar trends as weight gain. The feed conversion ratio (FCR) of fish fed Diet 1 was significantly higher than the other fish groups, but no significant differences were observed in FCRs of fish fed Diet 2, Diet 3 or Diet 4. There was also no significant difference in the hepatosomatic index (HSI) between the four diets. For fish that received Diets 2-4, containing artificial feed, higher protease activities were detected. A higher lipid content of the experimental diets also significantly increased lipase activities and body lipid content. No significant differences in amylase activity or body protein content were found between Diets 1–4. In conclusion, a variety of food components, including copepods and artificial feed, in the diet of silver pomfret significantly increased digestive enzyme activity and could improve growth performance.

Growth Performance of the Green Tiger Prawn Penaeus semisulcatus De Haan in Cages in the Gulf of Mannar off Mandapam, Southeast Coast of India

Two experiments were conducted in rectangular box type cages. In experiment 1, growth of juveniles was compared at two densities (13 ind.m -2 and 21 ind.m -2 ) with the clam meat. In experiment 2, growth of juveniles was studied at a single density (13 ind.m -2 ) but with two different feeds (squid and compound pellet diet). In experiment 1, growth of both male and female significantly differed between the two densities, being higher at the lower density. In experiment 2, average growth performance of both male and female was higher with the compound diet. All males in the four treatments attained maturity at the age of 5 months. All females at the lower density reached maturity at the age of 6 months; this finding illustrates the suitability of low density culture for the development of broodstock in cages in the sea. Growth parameters (L∞ and k) were estimated for each sex in each treatment. As growth significantly differed between treatments for both sexes in the two experiments, L∞ and k differed accordingly, revealing the possibility of an influence of density and diet on the growth parameters. In all four treatments for both sexes, lifespan for Penaeus semisulcatus is estimated to 3+ years. The results of this study revealed that growth parameters such as L∞ and k are subject to variation depending on density and diet of the species in question.

Heat Inactivation of Hepatitis A Virus and a Norovirus Surrogate in Soft-Shell Clams(Mya arenaria)

The effectiveness of different thermal treatments for inactivating two viruses in clams was evaluated. Soft-shell clam digestive glands experimentally contaminated with hepatitis A virus (HAV) or murine norovirus (MNV) were heated for 90, 180, or 300 seconds at 85°C or 90°C in glass vials or plastic bags with 200 g of soft-shell clam meat. Inactivation was measured by plaque assay and real-time reverse-transcription (RT)-polymerase chain reaction assay. Measured inactivation was similar using both assays. The 90°C for 90 seconds treatment reduced MNV-1 titer by 3.33 log cycles and HAV by 2.66 log cycles. At 90°C for 180 seconds, both MNV-1 and HAV were completely inactivated (titer reduced by 5.47 log cycles) in glass vials. In the presence of clam meat as well, HAV inactivation was complete at 90°C for 180 seconds. In general, HAV was more resistant to heat treatment than MNV-1, suggesting that it would require a more severe treatment than human norovirus for inactivation in soft-shell clams. The results of the present study should contribute to the development of strategies for controlling the spread of enteric viral illness via shellfish.

Preliminary Studies of Energy and Protein Requirements of Atlantic Horseshoe Crabs, Limulus polyphemus, Grown in Captivity

Population declines of horseshoe crabs (HSCs) have led to conflict regarding management strategies among commercial fishermen, biomedical companies, and environmentalists. These conflicts have also led to increased interest in HSC aquaculture. In this study, feeding trials were performed with juvenile HSCs to quantify dietary energy and protein requirements in order to optimize feed formulation and feeding regimes. Trials measured digestibility of two formulated dry feeds based on clam meat or fish meal. Juveniles were fed 3% of their body weight (BW), fecal matter was collected, and acid insoluble ash was used as a non-absorbed reference substance. Apparent digestibility of protein was found to be 93.2 and 90.8% and energy digestibility was 83.7 and 87.5% for the clam meal and fish meal feeds, respectively. Growth trials were conducted with juveniles (0.58–1.1 g) offering the two diets at increasing feeding levels in order to quantify their daily requirements for energy and protein. The results indicate HSCs would require 224 J of digestible energy and 8.7 mg of digestible protein for maintenance per day per gram body mass. The efficiency of utilization to deposit new growth above maintenance was relatively low and amounted to kDP = 0.11 and kDE = 0.13 for protein and energy, respectively.

Plasma lipid regulatory effect of compounded freshwater clam hydrolysate and Gracilaria insoluble dietary fibre

This study investigates the hypocholesterolemic effects of a diet containing freshwater clam hydrolysate (PX) and insoluble dietary fibre from whole Gracilaria (IDF). Freshwater clam meat and whole dried Gracilaria were separately extracted using hot water. The residual meat was hydrolysed at 50 °C by Protamex to obtain freshwater clam hydrolysate (PX). Levels of triacylglycerol and cholesterol in Sprague–Dawley (SD) rats were compared with those of rats fed diets containing casein and cellulose as a control. Plasma triacylglycerol levels decreased by 65.8%, 27.9%, and 44.3%, respectively, in PX10 (16.6% hydrolysate), IDF10 (13.0% IDF) and compounded PX10/IDF10 groups, while plasma total cholesterol levels decreased by 26.1%, 24.2%, and 17.1%, respectively. In the liver, triacylglycerol levels decreased by 27.6%, 21.0%, and 28.0%, respectively, while total cholesterol levels decreased by 50.0%, 38.5%, and 48.6%, respectively. The compound PX10/IDF10 diet group showed a higher excretion of faecal total cholesterol and bile acids levels than did the other groups.

Determination of elemental and nutrient composition of water, clam mantle and shell of the Volta clam (Galatea paradoxa) using neutron activation analysis

The Volta clam Galatea paradoxa is a highly priced shellfish providing nutrition, jobs and poverty alleviation for the inhabitants of the lower Volta estuary. Clams are filter feeders straining particulate materials in the surrounding water, thus concentrating microorganisms and other metal elements in the gut and mantle which present possible health hazards. The elemental composition of the water, clam mantle, gut, shell, and bottom sediments were determined using Neutron Activation Analysis for the presence of Ca, Cl, Cu, Mg, Mn, V, Fe, Co, Br, Na and K. Proximate analysis of the mantle for the levels of protein, fat, carbohydrate, ash, wood fiber, phosphorus, free fatty acids and energy were carried out using the method of the Association of Official Analytical Chemists. The riverine water was laden with heavy metals V, Co, Cu, Mn, and Fe, as well as Al. These same metallic elements were detected in higher concentrations in the bottom sediments. Bioaccumulation factor (BAF) which is the measure of the distribution of heavy metals between water and biota (Clam mantle and gut), ranged from 2 to 145 times, depending on the type of contaminant. The clam meat contained high protein (15.3 ± 0.2%), no crude fiber, low fat content (1.80 ± 0.11%), fatty acids as oleic (25.2 ± 0.1%), energy (85.5 ± 0.21 kcal/100 g), carbohydrates (22.10 ± 0.03%), P (485 ± 1 mg/100 g), Ca (793 ± 75 mg/kg), Mg (860.3 ± 90.0 mg/kg). The high concentration of Ca (21,402.7 ± 797.0 mg/kg), Fe (18,071.2 ± 94.0 mg/kg), K (96 ± 14 mg/kg), Mg (540.8 ± 81.1 mg/kg), Na (4,570.0 ± 0.2 mg/kg) gives credence to the use of the shell for poultry feed mineral supplements, and in the emulsion paint manufacturing industry.

Evaluation of Arthrospira fusiformis as a Protein Source in the Diet of Penaeus monodon Fabricius

The cyanobacterium Arthrospira fusiformis (AF) has a high protein content of 60%-65% and is rich in vitamins, minerals, fatty acids (gamma-linolenic acid), carotenoid, and other antioxidant pigments. A 60-day feeding trial was conducted using postlarval Penaeus monodon (0.041 g mean initial weight) to evaluate the efficacy of six isonitrogenous (40% protein) test diets containing various inclusion levels of AF. Clam meat was replaced with AF at an inclusion level of control, 5%, 10%, 20%, 30%, and 40%. The diet with 20% AF produced a significantly greater weight gain, specific growth rate, food conversion ratio, and protein efficiency ratio than all other diets (p<0.05). Further increase in the AF inclusion levels significantly decreased growth and feeding performance. Percentage survival and water stability of diet was significantly higher at inclusion levels of 10% and 20%. The results suggest that AF cannot serve as the sole protein source in the diet of P. monodon postlarvae, but can be effectively used as a supplementary protein source.

Closed and Open Clamlike Structures Formed by Hydrogen‐Bonded Pairs of Cyclotricatechylene Anions that Contain Cationic “Meat”

Clamming up: The hexaphenolic compound cyclotricatechylene, which has a bowl-shaped cavity, forms clamlike pairs that encapsulate cations (see picture). Variable hydrogen bonding allows two linked cyclotricatechylene clamshells to be in a closed arrangement when smaller cations such Rb(+) or Cs(+) provide the clam meat, whereas larger cations such as NMe(4) (+) and NEt(4) (+) cause the clam to be partially opened.

Liver oil of pharaoh cuttlefishSepia pharaonisEhrenberg, 1831 as a lipid source in the feed of giant freshwater prawn,Macrobrachium rosenbergii(De Man 1879)

The efficacy of pharaoh cuttlefish (Sepia pharaonis Ehrenberg, 1831) liver lipid in the feed for juveniles of giant freshwater prawn Macrobrachium rosenbergii (De Man 1879) was tested by feeding five experimental diets prepared using clam meat, groundnut oil cake, wheat bran, tapioca powder, vitamin–mineral mixture and cellulose powder as the major ingredients. The test diets T1, T2, T3, T4 and T5, containing five levels (1, 2, 3, 4 and 5%, respectively) of lipid, extracted from the liver of pharaoh cuttlefish, were fed to 30-day-old prawn juveniles for 60 days, in triplicates and compared against a control. Analysis of variance of the growth parameters showed that the juveniles fed with T2, containing 2% cuttlefish liver lipid with a total lipid content of 9.85% and lipid–carbohydrate ratio of 1 : 3.8, showed significantly better growth (P 2%. Addition of cuttlefish liver lipid led to an increase of ω-3 and ω-6 fatty acids in T2, the proportion of ω-6 being higher than the former. The crude lipid content of the body of test animals also increased with the increase in dietary lipid from 1.51% in T1 to 3.27% in T5. The present study indicates that cuttlefish liver lipid can be successfully used as a substitute for conventional lipid sources in rearing juveniles of giant freshwater prawn, an eco-friendly practice in recycling cuttlefish waste – a discarded fishery by-product.