17Z-Tetracosenyl 1-glycerol ether from the spongesCinachyra alloclada andUlosa ruetzleri

The 1-glycerol ether of 17Z-tetracosenol has been identified as a major constituent of the dichloromethanesoluble extracts of two marine sponges,Cinachyra alloclada andUlosa ruetzleri. Spectral analysis and chemical degradations led to the assigned structure. Batyl alcohol was also found, in lesser quantities, inU. ruetzleri, but not inC. alloclada.     

Phosphorous Levels in Peeled and Deveined Shrimp Treated with Sodium Tripolyphosphate

Using volumetric and spectrophotometric methods for the determination of phosphorous, untreated shrimp were shown to have high and variable phosphorous content. When peeled and deveined shrimp were treated with 0.5% and 1.0% sodium tripolyphosphate (STP) solutions, the STP uptake was shown to be low. At these low treatment concentrations the phosphorous content in the treated shrimp did not exceed the range of natural phosphorous found in untreated shrimp. When higher treatment concentrations were used, treated thrimp could be identified. The stability of STP in treated shrimp during frozen storage was investigated using a P³² STP isotope. After 2 wk of frozen storage at –26°C only 12% of the total activity could be attributed to STP. At the same time, pyrophosphate was present at a level of 25% and orthophosphate at 27%. During further frozen storage, the STP concentration remained at approxinately 12%, pyrophosphate dropped down to as low as 2% while orthophosphate gradually increased reaching 45% of total activity at the end of 10 wk storage period.     

Kinetics of Growth and Inhibition of Listeria monocytogenes in the Presence of Antioxidant Food Additives

Listeria monocytogenes strain Scott A in Tryptose Broth was treated with 100-300 ppm butylated hydroxyanisole (BHA), 300-700 ppm butylated hydroxytoluene (BHT) and 10-30 ppm tertiary butylhydroquinone (TBHQ). Resulting growth curves were fitted using the logistic model, and growth parameters [lag period (LP), generation time (GT), and maximum growth (MG)] were calculated. BHA and BHT inhibited Listeria monocytogenes by increasing LP and GT and decreasing MG. Extent of inhibition was concentration-dependent for cultures with BHA, but not with BHT. TBHQ at 10-30 ppm increased LP but did not affect other parameters. LP increased exponentially with increased BHA or TBHQ in Listeria culture. Concentrations of additive required to increase LP by one order of magnitude were 240 ppm for BHA and 26 ppm for TBHQ.     

Survival and Metabolic Activity of Listeria monocytogenes on Ready‐to‐Eat Roast Beef Stored at 4 °C

Three brands of commercial roast beef were purchased and artificially inoculated with a 5‐strain Listeria monocytogenes cocktail at 2 inoculation levels (approximately 3 and 6 Log CFU/g). Although all 3 brands contained sodium diacetate and sodium lactate, inoculated Listeria cocktail survived for 16 d in all 3 brands; significant increases in L. monocytogenes numbers were seen on inoculated Brand B roast beef on days 12 and 16. Numbers of L. monocytogenes increased to 4.14 Log CFU/g for the 3 Log CFU/g inoculation level and increased to 7.99 Log CFU/g for the 6 Log CFU/g inoculation level by day 16, with the pH values being 5.4 and 5.8 respectively. To measure the cell viability in potential biofilms formed, an Alamar blue assay was conducted. Brand B meat homogenate had the highest metabolic activities (P < 0.05). By comparing its metabolic activities to Brands A and C and the inoculated autoclaved meat homogenates, results indicated that the microflora present in Brand B may be the reason for high metabolic activities. Based on the denaturing gradient gel electrophoresis and the Shannon–Wiener diversity index analysis, the “Brand” factor significantly impacted the diversity index (P = 0.012) and Brand B had the highest microflora diversity (Shannon index 1.636 ± 0.011). Based on this study, results showed that antimicrobials cannot completely inhibit the growth of L. monocytogenes in ready‐to‐eat roast beef. Native microflora (both diversity and abundance), together with product formula, pH, antimicrobial concentrations, and storage conditions may all impact the survival and growth of L. monocytogenes.     

Thermal Expansion of Alkaline‐Doped Lanthanum Ferrite Near the Néel Temperature

The thermal expansion and magnetic behaviors of divalent, alkaline‐doped lanthanum ferrites (La_0.9M_0.1FeO₃, M=Ca, Sr, Ba) were assessed using a combination of dilatometry, magnetometry, time‐of‐flight neutron diffraction, and high‐temperature X‐ray diffraction. Néel temperatures were determined through vibrating sample magnetometry and correlated well with changes in thermal expansion behavior observed during both dilatometry and X‐ray diffraction. The Néel temperatures observed for pure, Ca‐doped, Sr‐doped, and Ba‐doped lanthanum ferrites were 471°C, 351°C, 465°C, and 466°C, respectively. The effect of divalent substitutions on the magnetic behavior are attributed to charge compensation mechanisms and structural changes in the material.     

Penetration of Sodium Tripolyphosphate into Fresh and Prefrozen Peeled and Deveined Shrimp

The distribution of sodium tripolyphosphate (STP) in peeled and deveined shrimp tails after treatment was investigated using P³² labeled STP. Fresh and frozen brown (Penaeus aztecus) and fresh and frozen white (Penaeus setiferus) shrimp were used in the study. Shrimp were treated in solutions of either 0.5%, 1%, 5%, or 10% STP that had been prepared using P³² labeled STP diluted with “cold” STP. The duration of treatment was either 20 sec, 1 min, 5 min, or 20 min. When shrimp were treated in 0.5% and 1% STP solutions, a phosphate concentration gradient was evident in the shrimp muscle. After such treatments, STP was shown to accumulate on the surface of the muscle preventing further STP uptake. At higher STP concentrations (5% and 10% solutions) prolonged time treatments overcame the concentration gradient as STP became equally distributed through the shrimp muscle (4.8 mm). No difference in the STP penetration mechanism between fresh and prefrozen treated shrimo was evident.