超高压处理对冷藏带鱼鱼丸保鲜效果的影响

为延长带鱼鱼丸保质期,以带鱼鱼丸为原料,分别在250、300、350 MPa压力下处理5 min,以冷藏期间鱼丸菌落总数、总挥发性盐基氮(total volatile base nitrogen,TVB-N)含量、pH值为指标,并结合感官评价、色值、凝胶强度及质地剖面分析,探究超高压处理对冷藏带鱼鱼丸保鲜效果的影响.结...     

生物抗氧化剂结合超高压技术对冷藏带鱼的保鲜效果

为提高冷藏带鱼的贮藏品质,以4℃冷藏带鱼为对照,分别单独使用超高压技术(290 MPa,6 min)、超高压技术(290 MPa,6 min)结合3种不同的复合生物抗氧化剂(2.5%羧甲基壳聚糖+0.05%VE、2.5%羧甲基壳聚糖+0.25%水溶性迷迭香提取物、0.05%VE+0.25%水溶性迷迭香提取物)保鲜带鱼,以感官评定、菌落总数、理化指标(挥发性盐基氮TVB-N、硫代巴比妥酸TBA、酸价AV、持水力WHC)为评价指标,测定带鱼在4℃冷藏20 d内的保鲜效果。研究结果表明:冷藏带鱼货架期为6 d,单超高压组的冷藏带鱼货架期为12 d,超高压结合抗氧化剂后可将冷藏带鱼货架期延长至18 d,经过抗氧化剂处理的超高压各组,其菌落总数TPC、挥发性盐基氮TVB-N、硫代巴比妥酸TBA、酸价AV均低于单独使用超高压组,更显著低于冷藏对照组。其中0.25%水溶性迷迭香提取物与0.05%VE复配后保鲜效果最佳,能显著抑制带鱼冷藏过程中的菌落总数,减缓蛋白质分解,且抑制脂肪氧化和水解的效果最强,有效地保持了冷藏带鱼的品质。     

不同生物保鲜剂对带鱼冷藏保鲜效果的比较

为比较各种生物保鲜剂对冷藏带鱼的保鲜效果,考察不同生物保鲜剂在水产品防腐保鲜的应用,将百里酚、Nisin、茶多酚、ε-聚赖氨酸配制成浓度为1 g/kg的保鲜液,乳酸菌发酵液稀释1倍得到乳酸菌发酵液保鲜液,浸渍带鱼10 min,4℃冷藏,以菌落总数、挥发性盐基氮(TVB-N)、pH和TBA值为检测指标,考察不同生物保鲜剂的防腐保鲜效果。结果表明,各种保鲜剂处理组的保鲜效果均优于对照组,其中ε-聚赖氨酸和乳酸菌发酵液处理组显示出较强的保鲜效果,相比于对照组和其他保鲜剂处理组,能够显著抑制带鱼冷藏过程中菌落总数、挥发性盐基氮和pH的增长(p<0.05)。茶多酚处理组显示出较强的抗氧化能力,延缓了带鱼冷藏过程中TBA值的升高。百里酚和Nisin处理组能够一定程度延缓了带鱼的腐败变质,但总体上,其保鲜效果弱于ε-聚赖氨酸和和乳酸菌发酵液处理组。综合评定微生物指标、理化和感官指标,ε-聚赖氨酸和和乳酸菌发酵液对带鱼冷藏的保鲜效果较好。     

超高压在冷藏肉类产品贮藏保鲜中的应用研究进展

超高压加工是一个物理过程,对食品中的维生素、色素和风味物质等小分子化合物无明显影响,从而可以较好地保持食品原有的营养。本文旨在探讨超高压技术在冷藏肉类产品贮藏保鲜中的应用现状及前景,分别对超高压在冷藏肉类产品的杀菌、抑酶、抗氧化以及其对冷藏肉类产品颜色、亮度和风味保持方面的应用进行阐述,分析存在的问题,为超高压技术在冷藏肉类产品贮藏保鲜方面的进一步研究提供参考。     

超高压处理对冷藏鲍鱼保鲜效果与品质变化的影响

本文以鲍鱼为材料,研究了超高压处理对鲍鱼体内微生物的消减作用和不同压力超高压处理后的鲍鱼在冷藏过程中挥发性盐基氮值、p H、脂肪氧化值、肌肉组织与硬度的变化情况,对比了热加工和超高压处理对鲍鱼品质变化的影响。研究结果显示,超高压具有良好的杀菌效果,鲍鱼经400 MPa和500 MPa处理10 min,体内菌落总数达到未检出状态,贮藏20 d后,仍符合生食标准。超高压处理能有效抑制鲍鱼挥发性盐基氮的产生,在4℃条件下保存30 d后TVB-N值仍小于35 mg/100 g。经超高压处理后的鲍鱼p H显著高于未加工鲍鱼,但4℃贮藏30 d后,超高压处理后的鲍鱼p H反而显著低于未加工鲍鱼;相比热加工和未加工的对照条件,超高压处理能延迟TBA值的升高,抑制脂肪氧化;组织切片和质构实验发现经超高压处理的鲍鱼肌肉纤维凝聚,肉质硬度升高,但随着贮藏时间的延长,硬度逐渐下降。结果表明,鲍鱼经400 MPa压力处理10 min,冷藏20 d后仍可生食,同时品质得到良好的提升。      

植物源防腐剂对带鱼保鲜效果研究

通过测定洋葱、生姜、大蒜三种植物源提取液浸泡后的带鱼的pH,TVB-N,菌落总数以及感官评定,将其与未处理的带鱼的相关数据进行对比以验证植物源防腐剂的防腐效果。结果表明,三种植物源防腐剂的保鲜效果由强到弱依次为:大蒜、生姜、洋葱。未经处理的带鱼块只能存放4～5 d,而经植物源防腐剂提取液浸泡后的带鱼块皆可存放6 d以上。且经处理的鱼块pH、菌落总数都保持相对较低水平。由此得知,这三种植物源防腐剂都具有良好的保鲜效果,值得对其做进一步开发研究。     

带鱼保鲜技术研究进展

通过对带鱼的低温保鲜(冷藏、冷冻、冰鲜、微冻)、超高压保鲜、气调保鲜与生物保鲜剂等几种常用保鲜方式予以综述,展望带鱼保鲜与鲜度评价的研究热点,以期为带鱼的贮藏保鲜研究提供理论参考。     

壳聚糖对黄鳝冷藏保鲜效果的研究

采用1.0%壳聚糖浸渍黄鳝后0℃冷藏保鲜,通过TVB-N值、pH、失水率、细菌总数、硬度等在贮藏过程中的变化考察壳聚糖对黄鳝冷藏保鲜的影响。结果表明,在0℃冷藏条件下,经壳聚糖处理的黄鳝的TVB-N值、pH、失水率、细菌总数均低于空白对照组,并且明显保持了样品的硬度。      

壳聚糖涂膜对无花果冷藏保鲜效果的研究

研究了壳聚糖涂膜法对无花果冷藏保鲜效果的影响,测定了无花果的失重率、多酚氧化酶活性、过氧化物酶活性,以及总酸度、VC含量、蛋白质含量和还原糖含量。结果表明:壳聚糖涂膜处理可有效防止无花果贮存时的失重率的增加;降低多酚氧化酶(PPO)和过氧化物酶(POD)的活性,利于防止无花果的褐变;维持了无花果总酸度、VC含量以及蛋白质含量,降低了还原糖含量,保持了无花果的品质。     

茶多酚对冷藏草鱼片保鲜效果的研究

为研究茶多酚对冷藏草鱼片的保鲜效果,将鲜活草鱼剖杀和清洗后,沥水3min,分别在0.25%、0.5%、1.0%、1.5%、2.0%的茶多酚溶液中浸泡5min,沥水3min,真空包装后于4℃保存,每5d以感官评分、细菌总数、pH、挥发性盐基氮(TVB-N)作为质量指标,测定草鱼在冷藏过程中的品质变化。结果表明:茶多酚处理能够明显抑制细菌生长繁殖,降低TVB-N,减缓感官品质的下降速度。结论:茶多酚对冷藏下的草鱼具有良好的抗菌和抗氧化的作用,能够明显的延缓草鱼的腐败变质。     

臭氧不同频次处理对无花果冷藏期保鲜效果的影响

为提高臭氧在果实防腐保鲜上的时效性及应用效果。以"玛斯义·陶芬"无花果鲜果为试材,对果实采后在臭氧一次处理基础上,于冷藏期(0℃±1℃)第7天和第14天分别进行臭氧第二次、第三次处理,并就不同频次臭氧处理对果实的保鲜效应进行比较研究。结果表明:臭氧处理明显延缓了冷藏期果实可溶性固形物、还原性糖含量的变化进程,显著抑制了果实腐烂率、褐变指数,提高了无花果冷藏期好果率和新鲜度(P<0.05),但果实还原性成分维生素C(VC)和可滴定酸含量可能受臭氧氧化剂量影响,却加速了降解;其中二次、三次臭氧处理对果实整体贮藏品质影响效应明显于一次处理,但不同频次处理间差异未达到显著水平(P>0.05),可能与重复处理时间点有关,可见臭氧贮存无花果应做好处理适宜剂量及重复处理适宜时间点的选择。     

High hydrostatic pressure treatment and storage of carrot and tomato juices: Antioxidant activity and microbial safety

The application of high hydrostatic pressure (HHP) (250 MPa, 35 °C for 15 min) and thermal treatment (80 °C for 1 min) reduced the microbial load of carrot and tomato juices to undetectable levels. Different combinations of HHP did not cause a significant change in the ascorbic acid content of either juice (P > 0.05). Both heat treatments (60 °C for 5–15 min and 80 °C for 1 min) resulted in a significant loss (P < 0.05) in the free‐radical scavenging activity as compared to untreated samples. HHP‐treated juices showed a small loss of antioxidants (below 10%) during storage. The ascorbic acid content of pressurized tomato and carrot juices remained over 70 and 45% after 30 days of storage, respectively. However, heat treatment caused a rapid decrease to 16–20%. Colour changes were minor (ΔE = 10) for pressurised juices but for heat‐pasteurised samples it was more intense and higher as a result of insufficient antioxidant activity. HHP treatment (250 MPa, 35 °C for 15 min) led to a better product with regard to anti‐radical scavenging capacity, ascorbic acid content and sensory properties (colour, pH) of the tomato and carrot juices compared to conventional pasteurisation. Therefore, HHP can be recommended not only for industrial production but also for safe storage of fresh juices, such as tomato and carrot, even at elevated storage temperatures (25 °C). Copyright © 2007 Society of Chemical Industry     

High hydrostatic pressure treatment of finfish to inactivate Anisakis simplex

High hydrostatic pressure has been demonstrated to be a useful technique for treating food to reduce the number of pathogenic organisms and to extend shelf life. Most research in this area has focused on bacteria. However, a concern in the sashimi (raw fish) industry is that nematode worms such as Anisakis simplex occur naturally in cold-water marine fish. The objectives of this research were to perform a pilot study to determine the effect of high hydrostatic pressure on the viability of Anisakis simplex larvae, commonly found in king salmon and arrowtooth flounder, and to evaluate the effects of high hydrostatic pressure on the color and texture of the fish fillets. Pieces of fish (ca. 100 g per bag) containing 13 to 118 larvae were exposed to pressures of up to 80,000 lb/in2 (552 MPa) for up to 180 s. The times and pressures required to kill 100% of the larvae were as follows: 30 to 60 s at 60,000 lb/in2 (414 MPa), 90 to 180 s at 40,000 lb/in2 (276 MPa), and 180 s at 30,000 lb/in2 (207 MPa). For all salmon treatments that killed 100% of the larvae, a significant increase in the whiteness of the flesh was observed. Although high hydrostatic pressure was effective in killing A. simplex larvae in raw fish fillets, its significant effect on the color and overall appearance of the fillet may limit its application to the processing of fish for raw-fish markets.     

High hydrostatic pressure effects on bacterial bioluminescence

The mechanism that leads to microbial inactivation by high hydrostatic pressure remains elusive. In this study, a high-pressure system interfaced with a photomultiplier tube (PMT) was developed to monitor cellular metabolism in situ using bioluminescent bacterial strains. Preliminary characterization of the system was performed using Pseudomonas fluorescens 5RL expressing lux proteins from Vibrio fischeri. Stepwise increases in pressure at 34 MPa and above resulted in decreased bioluminescence. Square wave exposure to pressures of 69, 103 and 138 MPa showed bioluminescence reductions greater than 95%, but when cells were returned to ambient pressure bioluminescence returned to 51, 38, and 4% of initial bioluminescence values, respectively. An Escherichia coli strain expressing lux proteins from V. fischeri was constructed to determine whether this reversible effect could be observed in another bacterial genus. Square wave perturbations of 69, 103 and 138 MPa resulted in bioluminescence reductions of about 94% at the highest pressure treatment. Upon decompression, bioluminescence returned to 74, 58 and 30% of the initial bioluminescence values for cells treated at 69, 103 and 138 MPa, respectively. These results suggest that square wave exposure to pressure up to 138 MPa induces reversible cell damage in P. fluorescens 5RL and E. coli VF lux.     

冰温保鲜和冷藏保鲜对生食大西洋鲑品质影响的比较研究

目的探讨冰温保鲜和冷藏保鲜对生食大西洋鲑品质变化的影响。方法将大西洋鲑分别置于-1.8℃冰温条件和4.0℃冷藏条件下贮藏,测定菌落总数、pH值、挥发性盐基氮(total volatile basic nitrogen,TVB-N)值、色差值、K值和感官评分,通过这一系列评价指标,综合分析大西洋鲑在冰温保鲜条件和冷藏保鲜条件下品质变化的不同。结果随着贮藏时间的延长, 2组的菌落总数值、TVB-N值、K值均呈上升趋势, pH值在冰温保鲜条件和冷藏保鲜条件下变化趋势相近,色差值在2个保鲜条件下波动变化没有明显差异,感官评分在2个不同温度条件下总体均呈现下降趋势。在冷藏保鲜条件下,生食大西洋鲑的货架期为2 d;在冰温保鲜条件下,生食大西洋鲑的货架期为5d。结论冰温保鲜方式可将生食大西洋鲑的货架期延长3d,与冷藏保鲜方式相比,冰温保鲜方式在大西洋鲑的贮藏过程中体现了良好的保鲜效果。     

High hydrostatic pressure treatment effects on selected tissue properties of fresh horticultural products

High hydrostatic pressure (HHP) treatments affect the integrity and function of biomembranes and proteins of fresh produces. Initially, pressure affects membrane permeability, directly linked to a reversible decline in cell turgor. Reversibility reflects the restoration of intracellular solute gradients by re-established membrane semi-permeability and functionality of membrane-bound proteins. Above a certain threshold, pressure effects become irreversible resulting in tissue damage. Combining cell pressure probe and tissue impedance measurements allows differentiation between reversible and irreversible effects. Thus, these parameters were comparatively investigated in both fresh red cabbage leaves and in radish tubers, species-specifically exposed to various pre-determined relevant HHP conditions (red cabbage: 150–200 MPa at 35–55 °C for 5–20 min; radish: 100–200 MPa, at 20–40 °C for 5–10 min). These specific treatments facilitated the evaluation of the transition between reversible changes in membrane and protein properties and irreversible damages. While turgor declined immediately after HHP treatments, tissue damage occurred only delayed. The two products differed in their responses to various HHP conditions. Generally, HHP effects were limited and reversible at (and certainly also below) 100 MPa but were amplified with intensity of pressure treatments.Industrial relevanceIncreasing food security aspects but also growing concerns against conventional thermal treatments demand the application of novel and gentle nonthermal hygienisation techniques such as high hydrostatic pressure (HHP) also for the production of fresh ready-to-eat salads. However, knowledge about potential impacts of different HHP ranges on metabolic functionality and freshness of fruits and vegetables, and thus produce quality, is still only sketchy.This study comprehensively differentiated the reversible and irreversible effects of processing conditions on the physiological and structural basis of HHP effects on fresh red cabbage leaves and radish tubers. It thus provides valuable information on the absolute limits of the applicability of HHP for safety of fresh produces. The fact that pressure treatments above 150 MPa always resulted in irreversible tissue damage indicated that even short-term HHP treatments at room temperature are not suitable for the gentle sanitation of perishable fresh produces but may probably be useful as quarantine measure against parasites and viruses.     

EGCG对冷藏金鲳鱼鱼片新鲜度品质的影响

以金鲳鱼为原料,探讨不同浓度(1、2、5 g/L)表没食子儿茶素没食子酸酯(EGCG)浸泡处理,真空包装,4℃贮藏条件协同作用对金鲳鱼片感官、p H、色泽、弹性、硬度、菌落总数、脂质氧化、挥发性盐基氮等新鲜度指标的影响。结果表明:在相同贮藏条件下,各组鱼片新鲜度呈现劣化态势。但与对照组相比,EGCG处理组p H变化趋势更加缓慢;感官指标显著优于对照组;鱼肉色泽随着保藏天数的增加,色差变大其中5 g/L EGCG处理组色差最小;EGCG可以有效降低金鲳鱼肉中细菌生长繁殖的速率;对照组TBA值上升趋势明显比EGCG处理组快,在第14 d,2、5 g/L EGCG处理组明显低于对照组,说明EGCG对鱼片脂质氧化有明显的抑制作用;同时,EGCG对鱼片挥发性盐基氮的生成具有抑制作用。故EGCG可有效减缓冷藏期间金鲳鱼片的品质的下降,使其货架期延长,且在1~5 g/L浓度范围内,金鲳鱼片的保鲜效果与EGCG溶液的浓度具有一定的正相关性。因此,EGCG作为保鲜剂应用到金鲳鱼鱼片的保鲜中具备良好的前景。      

High hydrostatic pressure treatment for manufacturing of garlic powder with improved microbial safety and antioxidant activity

The traditional method of manufacturing garlic powder (GP) that includes simple grinding of air-dried garlic slices has problems of microbial safety and a pungent flavour for this product. Microbiologically safe GP with a less pungent flavour and better antioxidant activities was manufactured using high hydrostatic pressure (HHP), wet grinding and freeze-drying process. The numbers of total aerobic bacteria and yeasts and molds in untreated (without HHP) GP were 3.64 and 2.47 log CFU/g respectively. Garlic powder treated with 600 MPa HHP for 5 min exhibited a total aerobes count of 1.62 CFU/g and a yeasts and molds count of 1.43 log CFU/g. The diallyl disulfide content, which is responsible for the pungent odour of garlic, was also significantly reduced by HHP due to a decrease in the alliinase activity. Hence, a novel process using HHP can help to produce GP with improved microbial safety, flavour and nutrition.     

冷激处理对黄桃保鲜效果的影响

采后黄桃用0℃的冰水浸泡30min,然后置于(0±1)℃下 贮藏,测定一些与保鲜效果有关的理化指标,结果发现, 冷激处理可以抑制黄桃果实的呼吸强度,降低聚半乳糖 醛酸酶(PG)活性,保持硬度,降低丙二醛(MDA)含量和 电解质渗出率。      

High hydrostatic pressure processing on microstructure of probiotic low-fat yogurt

The effect of milk processing on the microstructure of probiotic low-fat yogurt was studied. Skim milk fortified with skim milk powder was subjected to three treatments prior to innoculation: thermal treatment at 85 °C for 30 min, high hydrostatic pressure at 676 MPa for 5 min, and combined treatments of high hydrostatic pressure (HHP) and heat. The processed milk was then fermented by using two different starter cultures containing Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus acidophilus, and Bifidobacterium longum. The microstructure of heat-treated milk yogurt had fewer interconnected chains of irregularly shaped casein micelles, forming a network that enclosed the void spaces. On the other hand, microstructure of HHP yogurt had more interconnected clusters of densely aggregated protein of reduced particle size, with an appearance more spherical in shape, exhibiting a smoother more regular surface and presenting more uniform size distribution. The combined HHP and heat milk treatments led to compact yogurt gels with increasingly larger casein micelle clusters interspaced by void spaces, and exhibited a high degree of cross-linking. The rounded micelles tended to fuse and form small irregular aggregates in association with clumps of dense amorphous material, which resulted in improved gel texture and viscosity.