摘要:

ABSTRACTWe studied thermal denaturation of myofibrillar proteins from pre‐and post‐spawning hake by differential scanning calorimetry (DSC), and evaluated denaturation kinetics under both conditions. The denaturation enthalpies of all pre‐spawning fish muscle extracts were less than those from post‐spawning. The area under the DSC thermogram corresponding to myosin denaturation was smaller in myofibrillar extracts from pre‐spawning than from post‐spawning hake, while the areas corresponding to denaturation of actin were similar. Between 40 and 55°C the myosin denaturation rates were greater for post‐spawning than for pre‐spawning hake. Both entalphies and kinetic data indicated proteins of fish in a better biological condition (post‐spawned) denature more rapi

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb05262.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTCryoprotective effects of lactitol dihydrate at 2, 4, 6 and 8% levels in cod surimi were investigated and compared to an industrial control (1:1 mixture of sucrose/sorbitol at 8% w/w) and to a control without additive. Stability of protein functional properties was monitored by salt extractable protein and differential scanning calorimetry analyses, as well as texture profile analyses of cooked gels for surimi stored at − 12°C for 8 wk. Data revealed the excellent cryoprotective properties of lactitol. Moreover, the level of lactitol in surimi could be reduced to 5.7–6.4% w/w without significant alteration of stabilizing eff

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb05263.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTTwo shore‐based surimi plants in Alaska were investigated to determine microbial conditions of Alaska pollock flesh during processing. Median aerobic plate count (APC) was 2.0 × 103/g after mincing, 2.3 × 103/g after washing/screening, 4.2 × 104/g after refining and 1.6 × 104/g after dewatering. Reprocessing, needed for nonanalog grade surimi, resulted in APC of 1.2 × 105/g after a second refining and 3.0 × 105/g after a second dewatering. The APC for analog grade surimi was 5.5 × 104/g and 2.0 × 106/g for nonanalog grade surimi. Highest total coliform most probable number (MPN) of>1100/g was determined from a nonanalog grade surimi sample and from a mince that had been refined twice. HighestEscherichia coliMPN of 460/g was determined from t

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb05264.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTTextural hardening of fish mince during storage was investigated by examining texture and structure of unwashed and washed fish mince. Washing reduced TMAO and increased water‐binding ability, but did not prevent development of hard, rubbery texture in fish mince during frozen storage. Transmission electron microscopy showed more shrinkage of myofibrillar units (sarcomeres) occurred in washed than unwashed mince. Textural hardening of washed mince was thus related to increased freeze‐induced contraction of myofibrils. Removal of water‐soluble sarcoplasmic proteins facilitated freeze‐induced contraction of myofibrils, leading to textural hardening. This suggested that water soluble proteins retard sarcomere shrinkage resulting from freeze‐induced contraction/protein cros

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb05265.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTHeterotrophic bacteria isolated from two shore‐based surimi processing plants in Alaska were identified to the genus level. In one plant, the major bacterial constituents wereFlavobacteriumandPseudomonas, followed byMoraxella, Aeromonas, Lactobacillus, Serratia, andAcinetobacter.In the other plant, major bacterial groups wereFlavobacteriumandArthrobacter/Corynebacterium, followed byPseudomonasandAcinetobacter. Pseudomonas, Aeromonas, andSerratiawere capable of rapid growth as low as 8°C, with respective generation times 3.0, 3.1, and 3.6 hours. Freezing and thawing of surimi reduced microbial counts to 45–67% of the pre‐frozen load; however, the composition of the microbial flora was maintained. The plant environment was a potential source of microbial contami

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb05266.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThermal properties of surimi made from Alaska pollock (Theragra chalcogramma) were analyzed using differential scanning calorimetry (DSC) in the freezing range. Each dynamically corrected thermogram was used to determine initial freezing point, unfreezable water (bound water), apparent specific heat, enthalpy and unfrozen water weight fraction. When water content was controlled at 80.3% (wet basis), the cryoprotectant concentration had little effect on thermal properties in the unfrozen and fully frozen (‐40°C) ranges. However, the initial freezing point and thermal properties just below this point were significantly affected. The study also demonstrated the great potential of DSC for measuring and modeling frozen food thermal properti

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb05267.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThree bacterial proteases were selected for their activity on casein per unit cost. Conditions for inactivation were determined. Fish protein was hydrolyzed without water addition. Protein was solubilized faster with Pescalase 560 than with HT‐200 or Protease N. Increase of protease concentration was associated with a quadratic increase in soluble nitrogen. Yields of 13 to 15% in terms of whole fish were obtained at the pilot plant. Products contained 83 to 86% protein of which 70 to 80% was soluble. Reactive lysine was 70 to 85%. Nutritional evaluation with rats indicated hydrolysates had 10 to 15% lower nutritional value than casein. Results suggest fish protein hydrolysates can be used in the food industry for their solubility and nutritional valu

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb05268.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTLithium chloride yielded better extraction of fish muscle protein than sodium or potassium chloride under most conditions. In addition, constancy of extracted protein was better with lithium compared to potassium or sodium chlorides with respect to blending time, salt concentration, pH, temperature and foaming. With stored red hake muscle, LiCl was superior to NaCl with better extractability of protein and more linear reduction of extractability with storage time. Evidence indicated the superior performance of lithium compared to sodium was due to stabilization by lithium chloride of fish proteins towards denaturation.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb05269.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTAlbacore were killed by brain destruction, dressed, bled or left round, chilled in sea water/ice slurry at 1.1°C, and stored in ice. Fish were analyzed for 33 days for aerobic plate count (APC), pH, salt, histamine, trimethylamine nitrogen (TMA‐N), and nucleotide content. Dressed albacore cooled faster than round or bled albacore. No significant differences were evident in APC, pH, salt, TMA‐N, or nucleotide content of round, bled and dressed albacore. Histamine was detected only at day 33. TMA‐N, inosine monophosphate and hypoxanthine content, and nucleotide ratios appeared to be useful indices of storag

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb05270.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTProteases in grass shrimp (Penaeus monodon) digestive tract were extracted. Four fractions, A, B, C and D, demonstrated caseinolytic activity and were purified to electrophoretic homogeneity. A, C and D were trypsin‐like, while B was a chymotrypsin‐like protease. Optimal temperature for proteases A, B and C were 65°C, and that for D was 55°C for hydrolysis of casein. Optimal pH of proteases A and C was 8.0, and that of D was 7.0 for hydrolysis of p‐toluenesulfonyl‐L‐arginine methyl ester. Optimal pH of protease B for hydrolysis of N‐benzoyl‐L‐tyrosine ethyl ester was 8.0. Inactivation of 50 % enzyme activity in 5 min occurred at 67°C for protease B and 50°C for p

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1991.tb05271.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY