罗非鱼冷藏期间新鲜度变化及控制的研究

研究了罗非鱼冷藏期间新鲜度的变化及保鲜剂对其的影响,结果表明,在罗非鱼冷藏过程中,随着感官质量的下降,鱼体组织中组胺、三甲胺、氨基态氮含量增加。组胺和三甲胺的含量与鱼体新鲜程度之间呈显著的负相关关系。0～2℃冷藏罗非鱼的感官一级鲜度和感官二级鲜度的临界组胺含量分别为:(6.0±1.53)μg/g FW和(20.4±3.28)μg/g FW。用3种复合保鲜剂处理均能降低鱼体组织中组胺、三甲胺、氨基态氮的增加,延缓感官质量的下降。与对照相比,在3个保鲜处理中,保鲜效果以复合保鲜剂C最好。     

白鲢鱼片在冷藏和微冻条件下的鲜度和品质变化

以白鲢鱼为实验对象,通过测定菌落总数、挥发性盐基氮（total volatile basic nitrogen,TVB-N）值、pH值、K值、三甲胺（trimethylamine,TMA）值、2-硫代巴比妥酸（2-thiobarbituric acid,TBA）值等鲜度指标,结合感官评价,以期探究冷藏以及微冻条件下鲢鱼片的品质变化规律。结果表明,在4 ℃冷藏和－2 ℃微冻条件下贮藏的鲢鱼片TVB-N值、TMA值、菌落总数值均随贮藏时间的延长而呈增长趋势;pH值先降低后增高;感官分数值呈降低趋势。综合各项指标变化,4 ℃冷藏条件下鲢鱼片的货架期为6 d,－2 ℃微冻条件下货架期为18 d,与冷藏相比,微冻能明显延长白鲢鱼片的货架期。     

不同温度冻藏对军曹鱼片品质的影响

研究不同冻藏温度(－ 10、－ 18、－ 30℃)对军曹鱼片部分理化指标、质构特性及感官品质的影响。结果表明,冻藏温度对军曹鱼片的解冻汁液流失率、蒸煮损失率、盐溶蛋白含量、Ca2+-ATPase 活性和TBA 值(硫代巴比妥酸)均有显著性影响(P ＜ 0.05)。冻藏时间越长、冻藏温度越高,汁液流失率、蒸煮损失率、TBA 值增加越大,盐溶蛋白含量、Ca2+-ATPase 活性下降也越多,即保水性降低、蛋白质变性程度增大、脂肪氧化加快。TPA(质构分析)发现军曹鱼片的硬度和耐嚼性随着冻藏时间的延长均呈显著增加趋势(P ＜ 0.05),而回复性则显著下降(P ＜ 0.05);冻藏温度越低,相应的硬度和耐嚼性就越小,而回复性则越大。感官评价表明冻藏导致军曹鱼片的品质下降,冻藏温度越高,品质劣变就越严重。采用较低的温度(－ 30℃)冻藏可以最大限度的保持军曹鱼片的品质。     

冷藏期间草鱼和鲢鱼鱼片特征生物胺变化差异

旨在明确草鱼和鲢鱼鱼片冷藏过程中生物胺的动态变化规律以及其特征生物胺变化差异,测定分析了4℃贮藏条件下草鱼和鲢鱼片pH、挥发性盐基氮(TVB-N)、菌落总数(TVC)、感官评价以及生物胺含量的动态变化。结果表明,随着贮藏时间的延长,TVB-N、TVC呈明显上升趋势;草鱼和鲢鱼鱼片冷藏过程中苯乙胺、腐胺、酪胺及8种生物胺总量变化明显,且草鱼和鲢鱼鱼片中各生物胺显著变化的时间点分别为第10天和第8天。草鱼和鲢鱼片生物胺含量的差异变化主要发生在腐败后期,在贮藏第12天,草鱼、鲢鱼片间腐胺和酪胺含量差异显著(P0.05),其含量分别为(23.39±0.40),(44.46±1.88)mg/kg和(25.01±1.85),(50.84±1.50)mg/kg。经相关性分析显示,苯乙胺、腐胺、酪胺与草鱼片品质指标间显著相关(P0.05),可作为草鱼品质的监测指标;苯乙胺、腐胺、酪胺、尸胺与鲢鱼片品质指标间显著相关(P0.05),可作为鲢鱼片品质的评价指标。且冷藏期间草鱼和鲢鱼鱼片关键腐败时间点的酪胺和8种总生物胺的含量分别相近,可作为草鱼和鲢鱼片品质评价的共同指标。     

Evaluation of Shelf Life of Superchilled Cod (Gadus morhua) Fillets and the Influence of Temperature Fluctuations During Storage on Microbial and Chemical Quality Indicators

Quality changes of aerobically packed cod fillets stored under superchilling and abusive temperature conditions were characterized by the growth of specific spoilage organisms (SSO) and the production of microbial metabolites measured by an electronic nose along with traditional sensory and chemical analysis (total volatile basic nitrogen [TVB‐N], pH). A new process based on quick contact freezing and cold air blasting was used to achieve superchilling of fillets before chilled (0.5 °C) or superchilled (‐1.5 °C) storage. Photobacterium phosphoreum dominated under temperature abusive conditions coinciding with high levels of TVB‐N and increased electronic nose responses indicating increased levels of alcohols and aldehydes at sensory rejection. Dominating growth of Pseudomonas spp. in 1 batch was associated with the origin, the catching method, and the cooling conditions during processing. The superchilling process followed by superchilled storage (‐1.5 °C) extended the sensory shelf life of the fillets for at least 3 d compared with traditional process, resulting in a total shelf life of 15 d. High content of TVB‐N was observed in superchilled fillets at sensory rejection. P. phosphoreum counts were lower under superchilling conditions (6.0 to 6.8 log colony‐forming units [CFU]/g), compared with the traditionally processed chilled fillets (7.2 log CFU/g). However, H₂S‐producing bacteria appeared to grow steadily under superchilling conditions reaching counts as high as 7.6 log CFU/g at sensory rejection.     

Chitosan and Protein Coatings Affect Yield, Moisture Loss, and Lipid Oxidation of Pink Salmon (Oncorhynchus gorbuscha) Fillets During Frozen Storage

The effects of chitosan (CH1 = 1% and CH2 = 2% solution), egg albumin (EA), soy protein concentrate (SPC), pink salmon protein powder (PSP), and arrowtooth flounder protein powder (AFP) as edible coatings on quality of skinless pink salmon fillets were evaluated during 3 mo frozen storage. Coating with 2% chitosan (CH2) resulted in significantly higher yield than coating with PSP and AFP. The thaw yield of salmon fillets coated with CH2 was higher than those of the control and fillets coated with AFP. The noncoated, CH1‐, and CH2‐coated fillets had similar drip loss (0.4% to 1.2%), which was lower than those observed for PSP‐ and AFP‐coated fillets. All fillet samples had similar cook yield (84.2% to 88.8%). The fillet coated with CH1, CH2, SPC, and EA had significantly higher (P < 0.05) moisture content after thawing than the control noncoated fillets. Coating with CH1 and CH2 was effective in reducing about 50% relative moisture loss compared with the control noncoated fillets. Chitosan (CH1 and CH2) and SPC delayed lipid oxidation. There were no significant (P > 0.05) effects of coating on a*, b*, and whiteness values for cooked fillets after 3 mo frozen storage.     

Application of Artificial Neural Network to Predict K-Value,Inosine Mono-Phosphate,and Hypoxanthine Concentrations of Grass Carp (Ctenopharyngodon idellus) Fillets During Storage

K-value, inosine mono-phosphate, and hypoxanthine concentrations of grass carp (Ctenopharyngodon idellus) fillets were determined during storage at 273, 277, 281, 288, and 293 K. Simultaneously, a feed-forward artificial neural network was developed to predict these changes in grass carp fillets during storage, and a comparative study on K-value prediction between the artificial neural network and Arrhenius model was also performed. The results showed that the K-value and hypoxanthine concentrations increased with storage time, while inosine mono-phosphate reached a peak and then decreased with time. The artificial neural network was successful in predicting changes in the K-value, inosine mono-phosphate, and hypoxanthine concentrations throughout storage, and it was even more effective in predicting K-value with lower relative errors than the Arrhenius model. The high regression coefficient (R²) and low mean squared error indicated that the artificial neural network could be a potential tool in modeling changes in K-value, inosine mono-phosphate, and hypoxanthine concentrations of grass carp fillets within 273–293 K.     

超高压处理对冷藏鲈鱼片细菌群落结构的影响

为研究超高压处理对冷藏鲈鱼片贮藏期间细菌菌群结构的影响,以压力250 MPa,时间9 min的超高压条件处理鲈鱼片,并以0.1 MPa处理样品为对照组。将处理后的样品置于4℃冰箱中贮藏,分别在0,3,6,9,11,13,15 d进行总挥发性盐基氮(TVB-N)与微生物指标(细菌总数、希瓦氏菌数、假单胞菌数和嗜冷菌数)测定,并作相关性分析,评价超高压处理对冷藏鲈鱼片品质的影响。随后分别提取两组样品在贮藏前期、中期、中后期与末期4个阶段的宏基因组,通过高通量测序技术分析冷藏鲈鱼肉不同阶段的细菌菌群。结果表明,样品经超高压处理,其TVB-N值、细菌总数、假单胞菌数、希瓦氏菌数和嗜冷菌数等指标的上升速度明显缓于对照组。相关性分析表明,TVB-N值与微生物指标可作为鲜度评价指标,用于分析鲈鱼片超高压处理后贮藏期间的品质变化。高通量测序结果表明,对照组与处理组样品在贮藏前期的主要细菌有芽孢杆菌属、大洋芽孢杆菌属与乳球菌属;在贮藏中后期与末期两个阶段,超高压处理组与对照组的菌相组成呈显著差异,优势腐败菌种类不同,对照组在中后期的主要细菌为假单胞菌属,超高压处理组在中后期的主要细菌为嗜冷菌属,对照组末期主要腐败菌为嗜冷菌属、假单胞菌属、希瓦氏菌属和气单胞菌属,超高压处理组末期主要腐败菌为嗜冷菌数、假单胞菌属与耶尔森氏菌属。可见,超高压处理在抑制TVB-N值与微生物指标升高的同时,也对其贮藏期间的菌相组成产生明显的影响,使嗜冷菌与希瓦氏菌的生长受到抑制。     

Impact of Freezing Process on Salt Diffusivity of Seafood: Application to Salmon (Salmo salar) Using Conventional and Pressure Shift Freezing

The depression of the melting temperature of ice under pressure permits to obtain a rapid freezing of foods. The expected benefit lies in reduced water diffusion from the intra- toward the extracellular media, resulting in a reduced drip loss during thawing. Beside, the modification of the cellular structure induced by ice formation may affect the mass diffusivity of the flesh. In the present study, salmon was used as a model food. Slabs of salmon (1-cm thick) were frozen using blast air and pressure shift freezing at 200 MPa. The impact of the freezing process on the mass diffusivity of salt was evaluated using an aqueous solution (NaCl, 3% w/w). Results indicate that the effective mass diffusivity was slightly increased in comparison to non-frozen flesh when a rapid freezing process was used. This may be attributed to a change in the permeability of cell membranes caused by freezing and high pressure.     

Quality and Shelf Life of Cold and Frozen Rainbow Trout (Oncorhynchus mykiss) Fillets: Effects of Fish Protein-Based Biodegradable Coatings

The Klunzinger’s ponyfish (Equulites klunzingeri) protein powder extracted with acid or alkali aided process as a biodegradable coating material for rainbow trout (Oncorhynchus mykiss) fillets during cold (+2°C) and frozen storage (–18°C) were investigated. The coating with alkaline treated protein (AlPC) and acid treated protein (AcPC) extended the shelf life of fillets from 11 to 14 days in cold storage and improved the quality parameters in three months frozen storage period. According to total viable count and total psychrophile count results, bacteria grew more quickly in uncoated fillets than coated fillets. The protein-based coating did prevent spoilage of the rainbow trout fillets as reflected by a decrease in pH, total volatile base-nitrogen and free fatty acids during cold and frozen storage period. Therefore, this study demonstrated that fish protein-based coating had a positive effect on maintaining the rainbow trout fillets quality, and edible coatings from discard fish can offer a promising alternative for preserving fish fillets.     

真空贴体包装对鲟鱼片冷藏过程中品质变化的影响

本研究旨在探究4 ℃冷藏过程中真空贴体包装鲟鱼片的品质变化规律。以普通真空包装、托盘包装作对比,测定了冷藏过程中鲟鱼片菌落总数、硫代巴比妥酸反应产物（thibarbituric acid reactive substances,TBARS）值、挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量、生物胺含量、ATP及其关联物含量与K值等化学指标,pH值、感官得分、色泽、质构等物理指标,以及微生物菌落总数。结果表明：与普通真空包装（6 d）和托盘包装（3 d）相比,真空贴体包装可将鲟鱼片在4 ℃冷藏条件下的货架期延长至9 d,并可有效抑制鲟鱼片TBARS值、TVB-N含量、总生物胺含量、次黄嘌呤含量、K值、b*值等指标的上升和弹性、硬度、鲜味物质肌苷酸含量的下降速度。此外,真空贴体包装可增加产品美观性,提高消费者购买欲,因此具有广泛应用于水产品包装的前景。     

The effect of linseed and psyllium fibre on the gelling properties of unwashed mince from farmed meagre (Argyrosomus regius)

The gelling properties of farmed meagre (Argyrosomus regius) mince mixed with linseed and/or psyllium fibres (up to 4.0%, w/w) were studied. The effects of chilled storage time (15 days vs. 1 day) and cold gelling (setting at 2 ± 2 °C) were measured. Linseed addition increased ω3 PUFA content and worsened the gel products' texture. Psyllium functional fibre addition had only a negative effect upon breaking force and deformation, not affecting the remaining textural properties and improving water‐holding capacity (WHC) from 61–77 to 70–85%. The incorporation of 4.0% (w/w) psyllium seems to be advisable. Quality of heat‐induced meagre gels was unaffected by chilled storage time. Production of an acceptable cold set gel is feasible provided that enough time is allowed for completion of the setting process. Overall results showed a potential for combining small‐sized meagre (<2 kg) and psyllium fibres to produce high added‐value functional foods.     

Effect of Steam-Assisted Hybrid Cooking on Textural Quality Characteristics,Cooking Loss,and Free Moisture Content of Beef

Semitendinosus muscles were cooked in a steam-assisted hybrid oven and also convection ovens at three different oven temperatures (180, 210, and 240°C) until three different end point temperatures [65°C (medium-rare), 72°C (medium), 80°C (medium-well)] were reached. Textural properties of cooked beef were investigated by the Warner Bratzler shear test and texture profile analysis. Cooking loss and free moisture content of muscle tissue was determined for each cooking condition. In addition, sensory analysis was carried out in order to compare with the instrumental results and correlations between instrumental texture parameters and sensory results. Steam-assisted hybrid oven cooking of beef resulted in a tougher texture, higher cooking loss, and lower free moisture content than convection cooking. High correlation coefficients (r² > 0.70) were observed between instrumental texture measurements and sensory results for all ovens, especially in terms of tenderness. The free moisture content and adhesiveness values were also correlated well with juiciness (r² > 0.70) for all oven types.     

1-MCP处理对冷藏番荔枝果实贮藏品质和生理变化的影响

以“非洲骄傲”番荔枝果实为试材,研究了1-MCP(1-甲基环丙烯)处理对冷藏(15℃)番荔枝果实贮藏效果和生理变化的影响。结果表明:1.8μl/L1-MCP处理能显著提高番荔枝的好果率,延缓番荔枝贮藏前期TSS含量的上升,推迟其成熟软化进程;1-MCP处理还能显著抑制番荔枝果实VC含量的下降(p<0.01),提高果实贮藏后期SOD、POD和CAT的活性;同时,1-MCP处理抑制了果实中PPO活性的升高和MDA含量的积累。     

Composition of Main Carotenoids in Korean Red Pepper (Capsicum annuum, L) and Changes of Pigment Stability During the Drying and Storage Process

ABSTRACT: This study was conducted to identify main carotenoids in red pepper and to investigate pigment stability during drying and storage. The main pigments in saponified extracts were capsanthin, zeaxanthin, β-cryptoxanthin, β-carotene, and an unknown peak, which was considered to be capsorubin by spectrophotometry and liquid chromatography/mass spectrometry (LC/MS). Myristoylcapsanthin, lauroylmyristoylcapsanthin, and myristoylpalmitoylcapsanthin were identified from unsaponified extracts analyzing fragment ions by LC/MS. In capsanthin stability, the difference in drying method had the most influence until 2-mo storage, whereas after 2-mo storage, temperature became the major factor. Myristoylpalmitoylcapsanthin was more stable than myristoylcapsanthin during storage.