Carbon monoxide treatments to impart and retain muscle color in tilapia fillets

ABSTRACT:  Carbon monoxide (CO) has been used for improving the color of muscle foods. In the current study, we compared the postmortem treatment of tilapia fillets with 100% CO and euthanasia of live tilapia with CO for their ability to stabilize the color of white and red muscle of tilapia fillets. Both postmortem CO treatment and CO euthanasia were effective in increasing the redness ( a * value) and lightness ( L * value) of tilapia white and red muscle. Fillets obtained from CO-euthanized tilapia showed significantly higher a * and L * values during 1 mo of frozen storage at –20 °C and subsequent thawing and storage at 4 °C for 18 d. The amount of CO present in the red and white muscles decreased during the 18 d of storage at 4 °C. There was no significant difference in the pH, drip, or thaw loss of CO-treated tilapia fillets compared to the untreated fillets.     

Correlation between astaxanthin amount and a* value in fresh Atlantic salmon (Salmo salar) muscle during different irradiation doses

The amount of astaxanthin and a* value changes in fresh Atlantic salmon light and dark muscle during cold storage was studied for different e-beam doses (0, 1, 1.5, 2 and 3 kGy). Astaxanthin (mg/kg muscle) and a* value decreased with increasing irradiation dose for both fresh light and dark muscle. The level of irradiation dose gave high correlation between a* value and amount of astaxanthin. The reason for the change in colour or decrease in a* value of Atlantic salmon during irradiation could be due to the destruction of astaxanthin. The amount of astaxanthin and a* value of 1 kGy treated salmon fillets were not significantly different (p > 0.05) from that of the control but significantly different (p < 0.05) from other irradiation treatments. The colour (a* value) of salmon muscle was related to the content of astaxanthin, which decreased as irradiation increased. The amount of astaxanthin in light muscle was three to five times greater than dark muscle. This study demonstrated that irradiating salmon fillets at 1 kGy, can be successfully used and leads to no significant change in colour and amount of astaxanthin.     

Properties of hydrolysed saithe protein isolates prepared via pH shift process with and without dewatering

Fish protein hydrolysates (FPH) possess various bioactivities making them a desirable ingredient in health foods. Saithe is an underutilized fish species and an excellent candidate for FPH. To produce high quality FPH removing undesirable components prior to the hydrolysis process is preferred and possible via the pH-shift process. The objective was to produce and investigate the properties of hydrolyzed protein isolates produced from minced saithe trimmings. Saithe trimmings were minced, homogenized in water and subjected to two variations of a pH shift process with (A) and without (B) dewatering. The latter process has the advantage of being less complicated and less expensive which is beneficial to the industry. Both systems were adjusted to 3% protein, pH 8 and 45 °C and subjected to enzyme hydrolysis. Both hydrolysis processes led to almost identical SDS-page peptide makeup. Both FPHs had similar antioxidative activities evaluated using oxygen radical absorbance capacity (ORAC), iron chelation ability and (DPPH) radical scavenging ability assays. FPH from process A had significantly higher ACE inhibition ability compared to FPH from process B.These results demonstrate that saithe FPH has good antioxidative activities and a strong ability to inhibit ACE, and may thus have a potential as a bioactive food ingredient.     

ACE-inhibitory activity of tilapia protein hydrolysates

Fish processing wastes can be used for preparing bioactive peptides with various functionalities. Our objective was to evaluate the in vitro angiotensin converting enzyme (ACE) inhibitory activity of tilapia protein hydrolysates and its corresponding fractionates. Tilapia protein was alkali-solubilised at pH 11.0 and recovered at pH 5.5 to obtain a stable substrate. This substrate was hydrolysed using two enzymes, Cryotin-F or Flavourzyme, to 7.5% and 25% degree of hydrolysis (DH). The hydrolysates were ultra-filtered into three fractions: >30 kDa fraction, 10–30 kDa fraction, and <10 kDa fractions. Both hydrolysates and fractionates were tested for ACE inhibition. Results showed that both Cryotin and Flavourzyme hydrolysates with 25% DH gave maximum ACE inhibitory activity. Low MW peptides showed higher ACE inhibition than high MW peptides. The inhibitory activity of fractionates was lower than that of the corresponding hydrolysates, possibly due to separation and removal of synergistic peptides by ultrafiltration. Amongst fractionates, all the 7.5% DH Cryotin fractions and 25% DH Flavourzyme fractions exhibited optimum % ACE inhibition. The results of this research could be used for optimising enzyme parameters to obtain peptides from tilapia with optimum in vitro ACE inhibitory activity.     

Effect of pretreatment on lipid oxidation and fishy odour development in protein hydrolysates from the muscle of Indian mackerel

Impact of different pretreatments on chemical compositions of Indian mackerel mince was studied. Mince prepared using washing/membrane removal/alkaline solubilisation process (W–MR–Al) contained the lowest remaining myoglobin and haem iron content and also showed the lowest total lipid and phospholipid contents. When mince and W–MR–Al were hydrolysed using Alcalase for up to 120 min, a higher degree of hydrolysis (DH) was found in W–MR–Al after 30 min of hydrolysis. Furthermore, hydrolysate from W–MR–Al had lower peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and non-haem iron content throughout hydrolysis period (P < 0.05). When hydrolysate powder produced from mince and W–MR–Al (0–0.3% w/v) were fortified in milk, the former resulted in the lower likeness score (P < 0.05) at all levels used. The addition of the latter, for up to 0.2%, had no effect on likeness of all attributes, compared with milk without fortification (P > 0.05). Therefore, the appropriate pretreatment of mince yielded hydrolysate with lower fishy odour.     

Advanced laboratory techniques at the Armed Forces Institute of Pathology applicable to diagnosis and research in dermatology

The Armed Forces Institute of Pathology (AFIP) is well known for providing expert pathology in many specialties and educational courses for civilian and military personnel. Some of the departments at the AFIP have also developed expertise in various advanced laboratory techniques for diagnosis and research that are applicable to dermatology and are not available at most medical centers.     

6. Ammonium dynamics of puddled soils in relation to growth and yield of lowland rice

The release of non-exchangeable (fixed) NH ₄ ⁺ and the importance of exchangeable NH ₄ ⁺ at transplanting (initial exchangeable NH ₄ ⁺ ) for rice (Oryza sativa L.) growth was studied in representative lowland rice soils of the Philippines.The experiments showed that initial exchangeable ammonium behaved like fertilizer N and thus may serve as a valuable guideline for nitrogen fertilizer application rates when calculated on a hectare basis. By using the¹⁵N tracer technique it was found that nonexchangeable ammonium in soil may contribute to the nitrogen supplying capacity of lowland rice soils. Fixation and release of NH ₄ ⁺ seem to be more dependent on the form of clay minerals than on clay content. In soils rich in vermiculite non-exchangeable ammonium should be considered together with other available N sources such as exchangeable ammonium for N fertilizer recommendations for lowland rice.     

Synthesis and in vitro cytotoxicity of C(20)(RS)-camptothecin analogues modified at both B (or A) and E ring

A series of C(7) and C(20)-substituted camptothecin derivatives (12-14, 16-18) are prepared. Their syntheses and in vitro cytotoxicities are reported.     

Nuclear chromatin texture in prostatic lesions. I. PIN and adenocarcinoma

Contained in this report is a review of available data on pituitary cytokines in domestic species of agricultural importance. The concept is advanced that the pituitary gland is essential to appropriate generation of host defense mechanisms and thus should be considered among other tissues contributing to innate immunity. The functions of these intrapituitary cytokines, principally IL-6, are discussed in the context of potential regulation of the pituitary-adrenal axis (ACTH secretion) via intrapituitary PGE2 generation during the acute-phase response to infectious/inflammatory stimuli. Data from other species are cited as appropriate for comparative purposes and elaboration of proposed mechanisms. However, the scope of the review is not intended to comprehensively cover the vast literature on proinflammatory cytokines and prostaglandins generated peripherally and centrally during host responses to inflammatory stimuli.