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Meat quality attributes vary with chicken age. Understanding the relationship between poultry age and the quality of the meat would be beneficial for efficient poultry farming to meet market needs. The Korat hybrid chicken (KC) is a new crossbred chicken whose meat quality is distinct from that of commercial broiler (CB) chickens and has not been well characterized. In this study, we characterized the physico-chemical properties of KC meat and correlate the findings with Raman spectral data. The protein content of KC breast and thigh meat increased with age. The pH of thigh meat decreased, while the water-holding capacity of breast meat increased as the age of the chickens increased. The amount of cholesterol in breast meat decreased as the rearing period was extended. Inosine 5′-monophosphate and guanosine 5′-monophosphate of breast meat decreased as KC grew older. The shear force values of meat from older birds increased concomitantly with an increase in total collagen. Principle component analysis revealed that the meat quality of CB was greatly different from that of KC meat. High shear force values of KC meat at 20 wk of age were well correlated with an increase in the β-sheet structure (amide I) and amide III of collagen. Raman spectra at 3,207 cm−1 and relative α-helical content were negatively correlated with shear force values of KC breast meat. These could be used as markers to evaluate KC meat quality.

One of the defects commonly found in cooked marinated chicken breast products is a red blood spot (RBS), which is caused by undercooked blood in vessels. This problem was alleviated by microwave (MW) pre-heating for 6 to 7 min, followed by steaming. RBS formation decreased when samples were heated to a core temperature of 80°C and were completely eliminated at a core temperature of 82°C and 85°C when a MW pre-heating step was applied for 7 min. Based on synchrotron-based Fourier transform infrared spectroscopy (SR-FTIR), blood remaining in the blood vessel had a lower α-helical content when samples were cooked by the combination of MW heating and steaming as compared with those prepared by steaming alone (P0.05). MW pre-heating decreased cooking time by 28 to 48% as compared with steaming alone. Heating regimes had no effect on cooking loss, pH, water-holding capacity, and shear force. MW pre-heating for 7 min followed by steaming to a core temperature of 82°C appeared to be an effective heating regime to reduce the occurrence of RBS, with acceptable cooking loss.

Carnosine enrichment of slow-growing Korat chicken (KRC) meat helps differentiate KRC from mainstream chicken. We aimed to investigate the effects of β-alanine and L-histidine supplementation on the carnosine synthesis in and quality and secondary structure of proteins in slow-growing KRC meat. Four hundred 21-day-old female KRC were used, and a completely randomized design was applied. The chickens were divided into 4 experimental groups: basal diet (A), basal diet supplemented with 1.0% β-alanine (B), 0.5% L-histidine (C), and 1.0% β-alanine combined with 0.5% L-histidine (D). Each group consisted of 5 replicates (20 chickens per replicate). On d 70, 2 chickens per replicate were slaughtered, and the levels of carnosine, anserine, and thiobarbituric acid reactive substances were analyzed. Biochemical changes were monitored using synchrotron radiation-based Fourier transform infrared microspectroscopy; 5 chickens per replicate were slaughtered, and the meat quality was analyzed. Statistical analysis was performed using ANOVA and principal component analysis (PCA). Group D chickens exhibited the highest carnosine meat content, followed by those in groups B and C. However, amino acid supplementation did not affect anserine content and growth performance. Higher carnosine levels correlated with increasing pH

The Korat chicken (KR), developed in Thailand, is a slow-growing breed developed as an alternative breed for Thai chicken producers. The growing interest in slow-growing chicken meat, due to its unique taste, distinct texture, health benefits, and higher broiler welfare have led to higher market demand for KR. However, its low feed efficiency (FE) has a significant negative impact on farm profitability. Understanding the molecular mechanism regulating FE allows for designing a suitable selection program and contributing to breeding more efficient chicken for poultry production. Thus, the objective of our study was to investigate the proteome differences and possible pathways associated with FE in male KR using a label-free quantitative proteomic approach. Seventy-five KR males were individually evaluated for FE, and duodenum samples from 6 animals (3 high-FE and 3 low-FE chickens) were collected at 10 wk of age for differential abundant proteins (DAPs), protein networks, functional enrichment, and pathway analyses. In this study, we found 40 DAPs significantly associated with FE pathways, including glycolysis/gluconeogenesis, peroxisome, oxidative phosphorylation, tight junction, and cysteine and methionine metabolism. Thus, variations in observed DAPs or genes related to DAPs could be interesting biomarker candidates for selection for higher feed utilization efficiency in chicken.

Chicken breed is one of the key factors that influence meat quality. The quality attributes of breast meat from commercial broiler (CB), Thai native chicken (NC, Leung Hang Khao), and the crossbred Korat chicken (KC) were investigated via synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy, Fourier transform Raman (FT-Raman) spectroscopy, and physicochemical analysis. The protein and carbonyl contents of KC and NC meats were higher than that of CB meat, but the lipid content was lower (P0.05). CB meat was characterized by high moisture, lightness (L*), and presence of taste-active nucleotides, namely, inosine 5'-monophosphate (IMP) and guanosine 5'-monophosphate (GMP). Moreover, NC meat had the highest insoluble collagen and inosine contents (P0.05). The predominant protein secondary structures of KC and NC meats were β-turns and random coils, whereas α-helices were mainly found in CB meat. Based on principal component analysis, the meat quality and spectra were clearly separated by breeds. The high moisture and lipid content of meat corresponded to O-H stretching (3,203 cm

Chicken blood has limited utilization despite its high protein content. Production of a blood hydrolysate exhibiting angiotensin I-converting enzyme (ACE)–inhibitory activity would be means of valorizing chicken blood. The optimized conditions used to produce chicken blood corpuscle hydrolysate (BCH) by Alcalase were 51.1°C, 4% enzyme, and pH 9.6 for 6 h, resulting in a 35.8% degree of hydrolysis and 37.7% ACE inhibition at a peptide concentration of 0.2 mg/mL. The permeate of a 1-kDa membrane, BCH-III, showed a 2.5-fold increase in ACE inhibition compared with that of BCH. BCH-III was resistant to in vitro gastrointestinal digestion, whereas the BCH digesta exhibited an increased ACE-inhibitory activity after digestion. Both BCH and BCH-III were rich in hydrophobic amino acids. A single administration of BCH and BCH-III to spontaneously hypertensive rats at concentrations of 600 and 100 mg/kg, respectively, lowered the systolic blood pressure by −57.7 and −70.9 mmHg, respectively, 6 h after oral administration compared with the control group. The blood pressure–lowering effect of the 600 mg/kg BCH dose was comparable with that of the 100 mg/kg BCH-III dose after 4 wk of oral administration. Both BCH and BCH-III could be developed for use as nutraceutical products with antihypertensive effects.

Modulation of inflammation-related immune response on THP-1 macrophages of protein hydrolysates derived from tilapia mince, casein and pea protein, were investigated. The protein substrates were hydrolyzed by Virgibacillus halodenitrificans SK1-3-7 proteinase. The degree of hydrolysis (DH) of casein was observed to be the highest throughout the course of hydrolysis. When challenging THP-1 macrophages, tilapia mince hydrolysate (TMH) enhanced innate immunity through induction of IL-1β and COX-2 expression. Anti-inflammatory activity was observed in casein hydrolysate (CH) and pea protein hydrolysate (PPH) by attenuating lipopolysaccharide- (LPS) induced pro-inflammatory gene expression in THP-1 macrophages. CH suppressed IL-1β, IL-6, IL-8, TNF-α and COX-2, while PPH reduced LPS-induced IL-6 and TNF-α responses. In addition, CH and PPH showed stronger suppression of LPS-induced pro-inflammatory gene expression compared with non-hydrolyzed casein and pea protein. These results suggest that TMH, CH and PPH prepared from V. halodenitrificans SK1-3-7 proteinase are potential functional food ingredients with immunomodulatory activity.

The effects of in vitro gastrointestinal (GI) digestion on the antioxidative activity of hydrolysates prepared from chicken blood plasma and red blood cell (RBC) by pepsin and thermolysin were investigated. The pepsin-hydrolyzed plasma (PHP) showed the highest scavenging activity of ABTS radicals (P < 0.05). RBC and plasma hydrolysates prepared by pepsin were hydrolyzed by GI proteases to a greater extent than hydrolysates prepared by thermolysin as evidenced by MALDI-TOF mass spectra. The antioxidative activity of all digesta increased compared to their respective parent hydrolysates, and PHP digesta showed the highest activity (P < 0.05). The digesta of PHP and thermolysin-hydrolyzed plasma showed cytoprotective properties in a dose-dependent manner, and 100 μg/mL of PHP digesta exhibited the highest protection of HepG2 cells against tert-butyl hydroperoxide (P < 0.05). Based on dichloro-dihydro-fluorescein diacetate assay, PHP digesta exhibited the greatest intracellular reactive oxygen species scavenging activity of approximately 71% at 100 μg/mL (P < 0.05). The peptide sequencing of PHP digesta revealed that they contained less than 10 amino acid residues, with an average hydrophobicity of 18.6. Chicken blood plasma is a better protein source for protein hydrolysates, and their digesta showed higher antioxidant activity compared to RBCs.

Protein hydrolysate from frame, bone and skin (FBSH) of threadfin bream was prepared using Virgibacillus sp. SK33 proteinase and fractionated using sequential ultrafiltration membranes with molecular weight cut-offs (MWCO) of 30, 5 and 1 kDa, respectively. Four fractions, namely FBSH-I (>30 kDa), FBSH-II (5-30 kDa), FBSH-III (1-5 kDa), and FBSH-IV (

Korat-chicken breast and thigh were subjected to heating at 70, 100 or 121 °C for 30 min and simulated in vitro gastrointestinal digestion. At 70 or 100 °C heating, digests of breast possessed higher ACE inhibitory activity than those of thigh. The highest ACE inhibitory activity was found in the digest of breast cooked at 70 °C (B/H-70), whereas breast heated at 121 °C (B/H-121) exhibited the lowest. The 1-kDa permeate of the B/H-70 digest revealed higher permeability through colorectal adenocarcinoma monolayers and ACE inhibitory activity than did B/H-121. Among nine transported peptides, APP derived from myosin showed the highest ACE inhibition, with a non-competitive characteristic (Ki 0.93 μM). Molecular docking showed that APP interacts with ACE via hydrogen bonds, electrostatic and van der Waals interactions. In conclusion, mild thermal treatment of chicken breast resulted in a higher amount of transported peptides, exerting higher ACE inhibitory activity, which could lead to potential health benefits.

Antioxidant peptides of mungbean meal hydrolysed by Virgibacillus sp. SK37 proteinases (VH), Alcalase (AH) and Neutrase (NH) were investigated. The antioxidant activities based on 2,2′-azinobis (3-ethyl-benzothiazoline-6-sulphonate) (ABTS) radical-scavenging, ferric-reducing antioxidant power (FRAP) and metal chelation of VH were comparable to those of NH. VH was purified using ultrafiltration, ion exchange and gel filtration chromatography. The purified peptides (F37) from VH, which had the highest specific antioxidant activity, consisted of four peptides containing an arginine residue at their C-termini. In addition, the ABTS radical-scavenging activity of the purified peptides (F42) at 0.148 mg/ml was comparable to that of 1 mM of butylated hydroxytoluene (BHT). These two fractions were stable over a wide pH (4–10) and temperature (25–121 °C) range. Virgibacillus sp. SK37 proteinase is a potential processing-aid for the production of a mungbean meal hydrolyzate with antioxidant properties.

The angiotensin I-converting enzyme (ACE) inhibitory activity of protein hydrolysates from tilapia muscle fractions, namely mince (M), washed mince (WM), and sarcoplasmic protein (SP), were investigated. Each fraction was hydrolyzed by Virgibacillus halodenitrificans SK1-3-7 proteinases for up to 24 h. After 8 h of hydrolysis, the M hydrolysate (48% degree of hydrolysis (DH)) showed the highest ACE inhibitory activity, with an IC50 value of 0.54 mg/ml, while the SP hydrolysate exhibited the lowest DH and ACE inhibition. In vitro gastrointestinal digestion reduced the ACE inhibitory activity of the M hydrolysate but enhanced its transport across Caco-2 cell monolayers. The transported peptides were found to contain 3–4 amino acid residues showing strong ACE inhibition. The novel ACE inhibitory peptide with the highest inhibition was found to be MCS, with an IC50 value of 0.29 μM. Therefore, tilapia mince hydrolyzed by V. halodenitrificans proteinases contained ACE inhibitory peptides that are potentially bioavailable.

Fish sauce production relies on a natural fermentation process requiring 12-18 months for process completion. Virgibacillus sp. SK37 has been shown to be a potential strain for fish sauce acceleration. However, hydrolytic activity of proteinases bound at cell surface of this strain has not been well elucidated. Addition of 0.2 % CaCl(2) (w/w) in conjunction with starter cultures of Virgibacillus sp. SK 37 increased protein hydrolysis as measured by α-amino group content throughout fermentation (P0.05). Cell-bound proteinases from Virgibacillus sp. SK 37 were extracted into a free form by incubating the washed cells in Ca(2+)-free buffer at 37 °C for 2 h. Cell-bound proteinases revealed molecular mass of 19, 20, 22, 32, 34, and 44 kDa based on a synthetic peptide zymogram. The proteinases showed subtilisin-like serine characteristics with the highest activity at 50 °C and pH 8 and 11. Activity of the extracted proteinases increased ~4 times at ≥100 mM CaCl(2). In addition, CaCl(2) enhanced thermal stability of the extracted proteinases. Enzymes showed proteolytic activity in either the absence or presence of 10 and 25 % NaCl toward fish muscle, soy protein isolate, and casein substrates. Cell-bound proteinases were likely to play an important role in protein hydrolysis during fish sauce fermentation.

Aims: Virgibacillus sp. SK37 isolated from Thai fish sauce produced numerous NaCl-activated subtilisin-like proteinases. Our objectives were to purify, characterize and identify these extracellular proteinases. Methods and Results: Three major subtilisin-like enzymes including 19, 34 and 44 kDa were partially purified and showed maximum activity at pH 8, 55– 60� C, 25–30% NaCl and 70–100 mmol l )1 CaCl2. Enzymes showed stability at 0–30% NaCl and

The conformational changes and rheological properties of soluble sarcoplasmic proteins isolated from striped catfish (Pangasius hypophthalmus), treated at various pHs (2–12), were investigated. Isoelectric point of striped catfish sarcoplasmic proteins was determined to be pH 5. SDS–PAGE of sarcoplasmic proteins treated at various pHs, showed molecular masses ranging from 11 to 97 kDa. Most sarcoplasmic proteins, regardless of treated pHs, showed a molecular mass of 43 kDa. A decrease in total sulfhydryl content was observed when the pH was shifted away from 6, indicating disulfide formation at pH lower and higher than 6. Gradual increases of S0-ANS and S0-PRODAN were observed as pH increased from 6 to 12, indicating the unfolding of sarcoplasmic proteins during alkaline extraction. DSC thermograms of sarcoplasmic proteins treated at pH 5–9 exhibited an exothermic transition peak, probably due to disulfide bond formation, and/or hydrophobic interactions, which was highly related to the onset temperature of G′ rising. Gel network formation of sarcoplasmic proteins did not take place at extreme pHs ( 9) where proteins were highly charged while the viscoelastic properties of sarcoplasmic proteins were observed at pH 5.5–9. The highest G′ value at 90 °C was observed at pH 5.5 and 8 (P ⩽ 0.05). The gel point, a temperature at which G′ = G″, increased to higher temperature as pH was shifted away from 7.

An extracellular proteinase from Virgibacillus sp. SK33, isolated from 1 month-old fish sauce, was purified to electrophoretic homogeneity, using hydrophobic interaction chromatography and hydroxyapatite with purification fold of 2.5 and 7% yield. The anomalous molecular weight (MW) of 19 kDa was obtained from SDS–PAGE, whereas a MW of 33.7 kDa was determined by MALDI-TOF. Optimum conditions for catalytic activity were 55 °C and pH 7.5. The proteinase was strongly inhibited by phenylmethanesulfonyl fluoride (PMSF) and preferentially hydrolysed Suc-Ala-Ala-Pro-Phe-AMC, indicating a serine proteinase with subtilisin-like characteristics. K m and k cat of the purified proteinase were 27 μM and 12 s −1 , respectively. Proteinase activity, toward both synthetic and anchovy substrates, increased with NaCl up to 25%. The proteinase exhibited high stability in both the absence and presence of NaCl up to 25%. Approximately 2.5-fold increase in activity was observed in the presence of divalent cations, including Ca 2+ , Mg 2+ and Sr 2+ at 100 mM. MALDI-TOF MS and LC–ESI-MS/MS analyses, as well as N-terminal sequences, revealed that the purified enzyme did not match microbial proteinases in the database, indicating it to be a novel proteinase.

The cross-linking of β-lactoglobulin (BLG) was efficiently catalysed by microbial transglutaminase (MTG) but not by fish (threadfin bream) liver transglutaminase (FTG). BLG cross-linking was inhibited by 2 mM 5-(biotinamido) pentylamine (BPNH2) and MTG incorporated BPNH2 into BLG ∼5 times more than was FTG. The glutaminyl sites for the incorporation of BPNH2 into BLG by FTG and MTG were identified using matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF MS). MALDI-TOF MS analyses showed that MTG and FTG incorporated 4 and 1 residues of BPNH2 per molecule of BLG, respectively. The BPNH2-tagged BLG was digested by trypsin and BPNH2-tagged peptides were selectively purified by avidin-affinity chromatography. Amino acid sequences of BPNH2-tagged peptides were identified by comparing their MALDI-TOF mass spectra with the theoretical mass profiles from the MASCOT database. The BPNH2-modification sites catalysed by MTG were glutamine (Q)13, Q68, Q15 or Q20, Q155 or Q159, whilst FTG only incorporated BPNH2 into BLG at Q68. The different reactivities between FTG and MTG might be due to the different accessibilities of these TGases to the Q residues as well as to differences in substrate specificities.

Chemical and biochemical changes of aquacultured hybrid catfish fillet ( Clarias macrocephalus × Clarias gariepinus ) and its gel-forming ability as affected by age and sex of fish along with storage time were investigated. Fillets were stored at 4 °C for 0, 3, 6, 9, 12 and 15 days. There was no significant effect of sex and age of fish as well as storage time on fat, moisture and ash contents ( P > 0.05). The total protein, water soluble protein, and salt soluble protein contents of the fillets significantly decreased with storage time ( P P 2+ -ATPase activity and gel properties were observed as storage time increased. However, there was no significant effect of either sex or age of fish on textural properties of gel ( P > 0.05). Hybrid catfish fillet stored at 4 °C should be processed within 6 days.

Four fractions (P111, P21, P31, and P4) of proteinases were obtained from various purification steps including heat treatment (60 °C, 10 min), 30–60% ammonium sulfate precipitation, anion exchange, hydrophobic interaction, and gel filtration chromatography. Optimal temperature and pH of all fractions were 50–60 °C and 8.5, respectively. All partially purified proteinases preferably hydrolyzed substrates containing Arg at the P1 position. All proteinases were inhibited by soybean trypsin inhibitor, leupeptin, and N-tosyl- l -lysine chloromethyl ketone. Partially purified proteinases were stable at 35 °C up to 12 h. However, their activity decreased about 40% when incubated at the optimal temperature (50–55 °C) for 2 h. Only P111 was stable at its optimal temperature (60 °C) up to 12 h. Molecular weight (MW) of P111, P21, and P31 was estimated to be 27, 33, 37, 43, 48, 55, 60, and 65 kDa, while MW of P4 was 39 kDa based on activity staining. All partially purified proteinases hydrolyzed washed anchovy mince at 4.0 M NaCl, pH 8.5, at 35 °C and at their optimal temperatures (50–60 °C).

Maximum autolytic activity of Indian anchovy ( Stolephorus indicus ) was found at 60 °C. Autolytic activity decreased with increased NaCl concentration. Remaining autolytic activity at 25% NaCl (w/w) was 52%. Crude proteinase extracts exhibited the highest activity at 60 °C, using either casein or acid-denatured hemoglobin (dHb) as a substrate. Optimal pH of crude extracts was found at 8.5 for casein and 9.5 for dHb. Activity of crude extract decreased >50% when NaCl concentration was greater than 0.1 M. Crude extract was stable for up to 8 h at 4, 30, and 60 °C. Crude proteinase hydrolyzed several synthetic substrates of trypsin, including Boc-Asp(oBzl)-Pro-Arg-MCA, Boc-Val-Leu-Lys-MCA, and Boc-Gln-Ala-Arg-MCA. Soybean trypsin inhibitor (SBTI), leupeptin, phenylmethanesulfonyl fluoride (PMSF), and N -tosyl- l -lysine chloromethyl ketone (TLCK) inhibited activities of proteinase, indicating trypsin-like characteristics. Molecular weight of proteinases exhibiting caseinolytic activity at 4.0 M NaCl were estimated to be 63, 53, 46, 40, 35, and 31 kDa, using electrophoresis activity staining.

The changes in anthocyanins, phenolic compounds, and antioxidant activities of Thai purple rice cooked by various cooking devices, including an electric rice cooker, an autoclave and a microwave oven, were investigated. In raw rice, cyanidin-3-glucoside (cy-3-glu) and peonidin-3-glucoside (pn-3-glu) are predominant anthocyanins, whereas protocatechuic acid (PCA) and vanillic acid (VA) are major free phenolic acids, and ferulic acid (FA) and VA are major bound phenolic acids. The microwave cooking method resulted in a marked loss of phenolics, anthocyanins and antioxidant activities (p

Transglutaminase (TGase) from Tropical tilapia (Oreochromis niloticus) was purified to electrophoretic homogeneity using successive chromatographies of DEAE-Sephacel, Sephacryl S-4 HR and HiTrap Heparin with a yield and purification-fold of 12.9% and 69.8, respectively. The molecular weight (MW) of the purified tilapia TGase was estimated to be 85 kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The isoelectric point (pI) of tilapia TGase was 6.53. Optimal temperature and optimal pH of tilapia TGase were 37–50 °C and 7.5, respectively. Optimal concentrations of CaCl2 and dithiothreitol (DTT) were at 1.25 and 5 mM, respectively. The activity of TGase towards monodansylcadaverine (MDC) decreased as the NaCl concentration increased. Chelating agents, ethylenediaminetetraacetic acid (EDTA) and ethylene glycol-O,O′-bis(2-aminoethyl)-N,N,N′,N′-tetraacetic acid (EGTA), inhibited TGase activity. Tilapia TGase was strongly inactivated by ρ-chloromercuribenzoic acid (PCMB), N-ethylmaleimide (NEM), iodoacetamide (IAA), Cu2+, and Zn2+, suggesting a thiol group at the active site.

Optimum autolytic activities of lizardfish ( Saurida tumbil ) mince and surimi were at pH 6 and 7, respectively, with optimum temperature at 65 °C. Autolysis of surimi was mainly inhibited by phenylmethanesulfonyl fluoride and p -tosyl- l -phenylalanyl-chloromethylketone, indicating the involvement of myofibrillar-associated serine proteinase. Myosin heavy chain (MHC) and tropomyosin were preferentially hydrolyzed, resulting in poor textural properties. Based on TCA-soluble oligopeptide assay, egg white powder (EW) and whey protein concentrate (WPC) showed 77% and 96% inhibition, respectively. However, a significant loss of MHC was found. At any pre-incubation condition (25 °C/4 h, 40 °C/1 h and 65 °C/1 h), EW improved gel-forming ability of lizardfish surimi to a greater extent than WPC. Addition of 1% EW and pre-incubation at 25 °C resulted in an increase of higher molecular weight cross-linked proteins, corresponding to a twofold increase in the breaking force.

The NaCl-activated and detergent-stable proteinases from Virgibacillus halodenitrificans SK1-3-7 isolated from fish sauce fermentation were purified and characterized. The enzymes with molecular masses of 20 and 36 kDa showed caseinolytic activity on a zymogram. Optimum azocaseinolytic activity was at 60 °C and pH 9. The proteolytic activity increased in the presence of 10 mM CaCl2 and 0.5 M NaCl and showed high stability at 0–2 M NaCl. The enzymes were stable at pH 4–10 and 10–50 °C. The enzymes preferably hydrolyzed Suc-Ala-Ala-Pro-Phe-pNA and were completely inhibited by phenylmethanesulfonyl fluoride (PMSF), showing subtilisin-like characteristics. Activity and stability remained high in the presence of H2O2 and various surfactants. The enzymes exhibited high stability (>95 %) in various organic solvents (DMSO, butanol, ethanol, 2-propanol, and acetonitrile) at concentration of 50 %. The V. halodenitrificans SK1-3–7 proteinases showed potential as a biocatalyst in aqueous-organic solvent systems and as an additive in laundry detergent.

Halophilic lactic acid bacteria were isolated from fish sauce mashes fermented at 1 to 12 months. Seven out of sixty-four isolates were selected according to their proteolytic activity and growth at 25% NaCl for characterization and investigation of volatile compound production. All selected isolates were Gram-positive cocci with pairs/tetrads and grew at 0-25% NaCl, pH 4.5-9.0. Results of 16S rRNA gene sequence analysis showed 99% homology to Tetragenococcus halophilus ATCC 33315. The restriction fragment length polymorphism (RFLP) patterns of all isolates were also similar to those of T. halophilus ATCC 33315. These isolates were, thus, identified as T. halophilus. All isolates hydrolyzed fish protein in the medium containing 25% NaCl. Intracellular aminopeptidase of 7 isolates exhibited the highest activity of 2.85-3.67 U/ml toward Ala-p-nitroanilide (Ala-pNA). T.halophilus strains MS33 and M11 showed the highest alanyl aminopeptidase activity (P

Natural actomyosin (NAM) from Pacific whiting (PW) showed thermal transition temperatures by circular dichroism at 31.8 and 43.1°C, which were lower than those of threadfin bream (TB) NAM, 35.0 and 49.3°C. Endothermic transitions of PW-NAM by differential scanning calorimetry were at 31.8, 42.1 and 75.3°C, compared to 36.1, 50.9 and 78.4°C for TB-NAM. Based on surface hydrophobicity, α-helical content, and solubility, PW-NAM unfolded to a greater extent than did TB-NAM when incubated at 25°C for 4h and 40°C for 2h, suggesting its lower thermal stability. Transglutaminase generally catalyzed more extensive cross-linking of PW-myosin heavy chain (MHC) than TB-MHC, and the MHC cross-linking mediated by microbial transglutaminase (MTG) was greater than by fish transglutaminase (FTG). Textural properties of PW-NAM gels increased approximately 3.6-6.1-fold and 1.3-1.5-fold in the presence of MTG and FTG, respectively.