保鲜酸奶保质期的研究

通过单因素试验、正交试验确定长效保鲜酸奶的最佳操作参数。试验结果表明:长效保鲜酸奶的最佳工艺参数为A1B1C1,即非脂乳固体含量为15.3%;嗜热链球菌∶保加利亚乳杆菌=2∶1;采用无菌灌装的方式,可使酸奶在2℃～8℃温度条件下其保质期延长到32 d,乳酸菌活菌数为6.3×108/mL,且具有良好的风味和质地。     

On-Site NIR Spectroscopy to Control the Shelf Life of Pork Meat

Control of meat shelf-life includes the time that it remains in the exhibitor of sale (such as the supermarket) until its rejection for the consumer, or withdrawal due to expiry date. Near infrared spectroscopy (NIRS) is one of the most promising techniques for large-scale meat quality control. This study investigated the potential of on-site NIRS portable instrumentation-based models to predict three microbiological parameters to establish if pork meat is acceptable or not for consumption (aerobic Mesophilous microorganisms, Enterobacteriaceae, and lactic acid bacteria) and pH to quality control food preservation and shelf-life extension on intact slices of pork meat packaged under two different modified atmospheres. NIR calibrations were developed by using an on-site Phazir instrument (Polychromix, Wilmington, MA, USA) in the range 1,600–2,400 nm. A total of 252 samples of pork meat slices were directly scanned twice in reflectance mode on trays, once before and another one after removing the film cover at 1, 3, 5, 7, 9, 12, and 15 days of storage. Results showed that spectra of meat acceptable or not for consumption have marked differences around 1,660 nm. NIRS quantitative prediction models showed r ² values between 0.19 and 0.65 for the microbiological parameters assayed. The developed NIRS methodology makes possible on-site prediction of microbiological status of pork meat with a standard error of cross-validation around 1 log cfu/g. Results have shown that modified atmosphere packaging has no influence on calibration statistics.     

应用硅胶提高啤酒保质期的试验

论述了硅胶的特性,对亮爽Ｂ２８０硅胶的过滤性能以及改进啤酒光泽和浊度、提高保质期等方面进行了试验。结果表明,Ｂ２８０硅胶添加量３００ｇ／ｍ＾３啤酒,过滤时进出口压差仅为０．０４ＭＰａ,过滤性能好;啤酒清亮度和泡持性提高,两个月后,啤酒仍保持清亮。     

Rapid Evaluation of Poultry Meat Shelf Life Using PTR-MS

The use of proton transfer reaction mass spectrometry (PTR-MS) for freshness classification of chicken and turkey meat samples was investigated. A number of volatile organic compounds (VOCs) were selected based on the correlation (>?95%) of their concentration during storage at 4 °C over a period of 5 days with the results of the microbial analysis. In order to verify if the selected compounds are not sample-specific, a number of samples sourced from various retailers were classified using the concentration of these compounds in the samples’ volatile fraction as input variables. The classification was performed using the support vector machines (SVM) supervised pattern recognition algorithm. It was concluded that it is possible to evaluate the shelf life of meat samples obtained from the same source based on the results of a prior analysis. The PTR-MS fingerprint approach might supplement the currently used methods of shelf life evaluation of poultry due to the short time and non-destructive nature of measurement and ease of quantitative analysis.     

热分割和冷分割对小包装鲜肉货架期的影响

采用冷、热分割处理之间的对比,研究了两种分割方式下猪肉的色泽红度值a*、汁液流失率、菌落总数、TVB-N、感官指标的变化情况。结果表明:贮藏过程中,冷分割肉的汁液流失率、TVB-N值显著低于热分割肉(P<0.01),感官指标优于热分割肉且货架期比热分割肉的长;但两种处理分割肉的色泽红度a*值和TBA值差异不显著(p>0.05)。通过试验可以得出,与热分割相比,冷分割能延长鲜肉货架期2-3天。     

出口冰鲜鸡肉保质期限的研究

在检疫卫生注册的出口鸡肉加工厂,在正常的生产卫生条件下,将加工的鸡肉产品速冻,使其中心温度达到-1±0.5℃后,在-1℃、0℃、4℃、10℃五种不同保存温度下,对冰鲜肉进行保质期限试验研究。通过感官检查和实验室检查冰鲜肉的品质变化,确定了不同保存温度下冰鲜鸡肉的最佳保质期限。     

Overall Quality Throughout Shelf Life of Minimally Fresh Processed Fennel

ABSTRACT: The keeping quality of minimally fresh processed fennel up to 14 d at 0 °C under modified atmosphere packaging was studied. Samples of 1 cm³ diced fennel washed for 1 min with chlorinated (100 mg/L) water were placed in 35 μm oriented polypropylene (PP) bags or in PP baskets heat-sealed with unperforated or perforated (control) PP film. Changes in respiratory activity, ethylene emission, color, sugars content, chemical parameters, browning, decay, microbial growth, and sensory attributes were monitored. Respiratory activity in diced fennel was 1.5–fold higher than that for whole bulbs, and slight differences in ethylene emission between both whole and fresh processed fennel were found. A gas composition within both kinds of unperforated packages of about 11 to 13 kPa O₂ and 9 to 12 kPa CO₂ was reached. At the end of storage of fennel dices under this atmosphere, total plate counts were lower than legal limit for safe consumption. At any moment, neither physiological disorders nor decay developed. Although after 14 d a slight browning on the dices surface appeared, levels of sensorial attributes higher than acceptable for commercial purposes were reached.     

Functional Properties and Shelf Life of Fresh Surimi from Pacific Whiting

Total aerobic plate count (APC), shear stress, shear strain, and color of fresh Pacific whiting surimi stored at 5°C were determined at day 0, 1, 3, 5, and 7. Frozen surimi was prepared with four levels of cryoprotectams (0, 3, 6, and 9%) and was compared with fresh surimi for gelforming ability. Fresh Pacific whiting surimi had a shelf life of 5 days. The gel functionality remained unchanged throughout the storage time. Strain values of fresh surimi were not different from those of frozen surimi with 9% cryoprotectants, but stress values of fresh surimi were almost three times higher than those of frozen surimi.     

Sorbitol Increases Shelf Life of Fresh Mushrooms Stored in Conventional Packages

Trays containing 100g of mushrooms overwrapped with PVC film were held at 12°C. Two 3 mm holes were made on top of the ovetwrap for ventilation and a Tyvek^R pouch containing sorbitol was placed at the bottom of the tray before storage. Surface moisture content of mushrooms decreased in the presence of sorbitol. Mushrooms packaged with 10g sorbitol had a constant surface moisture content and those packaged with 15g sorbitol had the best overall color. Principal component analysis of Vis-NIR spectra revealed that surface moisture content affected the scattering of incident light and mushroom color. Lowering of the in-package relative humidity did not affect the maturation rate of mushrooms, but reduced bacterial growth, suggesting that improvement in color was probably due to reduced bacterial activity.     

Using A New Measure To Define Shelf Life Of Fresh Whitefish

An acceptor set size measure was successfully employed to examine shelf life trade-offs when fresh lake whitefish fillets (Coregonus clupeaformis) were dipped in 0.0, 2.5 or 5.0% (w/v) potassium sorbate, packaged in low, intermediate, or higher barrier bags, placed in 100% CO₂ modified atmosphere packaging system and held under refrigeration at less than 3°C. When sorbate was varied, shifts in acceptor size indicated that fillets dipped in 5.0% sorbate had the longest shelf life, exceeding 14 days. No significant difference was found when film permeability was varied. For all barrier films, shelf life exceeded 15 days although the low barrier bag had smaller acceptor sizes.     

复合保鲜剂对冷鲜肉货架期的影响

采用复合保鲜剂1%醋酸+3%柠檬酸+0.1%抗坏血酸和1%醋酸+1%乳酸+0.2%茶多酚对冷却肉进行处理,分别在0、3、6、9天测定样品的菌落总数、大肠菌群和挥发性盐基氮,并对样品的颜色和感官性状进行评价。结果表明:复合保鲜剂1%醋酸溶液+1%乳酸+0.2%茶多酚可使鲜肉在第6天时,菌落总数、大肠菌群、挥发性盐基氮在鲜肉要求范围之内,并且感官状态良好,该复合试剂能够达到延长冷鲜肉货架期的目的。     

Antimicrobial and Antioxidative Strategies to Reduce Pathogens and Extend the Shelf Life of Fresh Red Meats

Abstract: The shelf life of packaged fresh red meats is most frequently determined by the activity of microorganisms, which results in the development of off‐odors, gas, and slime, but it is also influenced by biochemical factors such as lipid radical chain and pigment oxidation causing undesirable flavors and surface discoloration. The predominant bacteria associated with spoilage of refrigerated meats are Pseudomonas, Acinetobacter/Moraxella (Psychrobacter), Shewanella putrefaciens, lactic acid bacteria, Enterobacteriaceae, and Brochothrix thermosphacta. The spoilage potential of these organisms and factors influencing their impact on meat quality are discussed. High O₂‐modified atmosphere (80% O₂+ 20% CO₂) packaging (MAP) is commonly used for meat retail display but vacuum packaging remains the major MAP method used for meat distribution. Two‐step master packaging (outer anoxic‐20% CO₂+ 80% N₂/inner gas‐permeable film) is used for centralized MAP distribution, but CO use (0.4%) in low O₂ packaging systems is limited by consumer uncertainty that CO may mask spoilage. Active packaging where the film contributes more than a gas/physical barrier is an important technology and has been studied widely. Its application in combination with MAP is very promising but impediments remain to its widespread industrial use. The influence of processing technologies including modified atmospheres on lipid oxidation and discoloration of meats are analyzed. Because both organic acids and antioxidants have been evaluated for their effects on microorganism growth, in concert with the prevention of lipid oxidation, work in this area is examined.     

鲜食马铃薯货架期与品质保持关键技术研究

以"中薯3号"马铃薯为研究对象,考察1-甲基环丙烯(1-MCP)、包装材料以及光照条件对鲜食马铃薯常温(25℃~30℃)货架品质的影响。结果表明,1-MCP浓度和光照方式对其叶绿素和龙葵素含量的影响均达到了显著性水平(p0.05),且叶绿素含量变化与龙葵素含量变化呈正相关;而对马铃薯硬度、色差和淀粉含量影响不显著(p0.05)。通过正交试验和方差分析,确立最佳贮藏条件为0.35 mg/L 1-MCP、PE包装和避光,为马铃薯常温货架品质控制以及延长货架期提供理论支持。     

生鲜鸡肉货架期预测模型的建立与评价

为了建立生鲜鸡肉货架期的动力学模型,将自然污染的生鲜鸡肉经PS/PE托盘包装后,置于0、5、10、15、20、25℃贮藏,分别测定不同贮藏时间的假单胞菌数量,同时对5℃贮藏的生鲜鸡肉进行品质分析,确定腐败限控量。结果表明:假单胞菌用来预测生鲜鸡肉时的腐败限控量为5.39(lg(CFU/g)),Gompertz函数能很好的描述假单胞菌在不同温度下的生长动态,建立6种温度条件下假单胞菌在生鲜鸡肉中的生长模型。采用Belehradek方程描述温度对最大比生长速率和延滞时间的影响,呈现良好线性关系,模型残差值的绝对值均小于0.07,表明该模型描述的温度与比生长速率和延滞时间是可信的。在此基础上,建立了生鲜鸡肉贮藏过程中货架期的预测模型。     

冰鲜鸡肉品质及其货架期的研究进展与展望

相对于热鲜鸡肉和冷冻鸡肉,冰鲜鸡肉在口感、风味、新鲜度以及营养等方面具有很大优势,具有很好的市场发展前景。但冰鲜鸡肉的品质在生产加工和流通过程中容易发生腐败变质。随着消费者食品安全意识的日益提高,冰鲜鸡肉的品质及其货架期受到越来越多的关注。本文总结了冰鲜鸡肉的品质表征指标;阐述了微生物因素、物理因素以及化学因素对冰鲜鸡肉品质的影响;比较了化学、超高压和辐照等6种保鲜技术对冰鲜鸡肉保鲜的效果及特点;结合食品货架期预测模型,梳理了已有预测冰鲜鸡肉货架期的相关研究;最后分析了冰鲜鸡肉品质及其货架期的研究现状,并对其未来的研究趋势进行了展望,指出随着研究技术、手段和保鲜技术的不断发展,冰鲜鸡肉货架期的研究也将不断向实用和智能化的方向发展。     

鲜熟面条贮藏品质变化及货架期研究

为了明确鲜熟面条在不同贮藏温度下品质指标的变化情况,确定出不同贮藏温度下鲜熟面条的货架期,将制作好的鲜熟面条分别于0、4、10、15、20、25℃条件下贮藏,定期取样,测定其感官品质、pH值、质构品质和菌落总数,分析各项指标随贮藏时间的变化及其差异。结果表明,不同贮藏温度下,随着贮藏时间的延长,鲜熟面条的感官品质、pH值、弹性和黏聚性逐渐降低,硬度则先增大后减小,菌落总数逐渐增大;在0、4、10、15、20、25℃的贮藏条件下,鲜熟面条的货架期分别为126、91、17、11、5、4 d;pH值、菌落总数是评价鲜熟面条货架期较好的指标,其阈值分别为6.24和10~(5.87)CFU/g;温度对鲜熟面条品质及货架期有显著影响,低温(0、4℃)贮藏可使鲜熟面条货架期延长至3个月以上。     

MAP结合真空预处理延长鲜牛肉货架期

通过采用真空预处理后进行气调包装技术，对生鲜牛肉冷藏过程中一系列品质的变化进行了研究，找到了延长牛肉货架期的较佳条件．主要考察了牛肉在不同的预处理终温、预处理压力及综合优化条件下保鲜效果的优劣．结果表明，选择预处理终温为4℃，预处理压力为1200Pa，联合气调包装充入体积分数40％的O2，25％的CO2气体时，保鲜效果较佳，可使牛肉货架期延长至14d以上．     

安全包装有效延长货架期保障鲜奶品质

众所周知，牛奶是非常容易被污染、易变质的敏感高营养品，如何尽量的减少牛奶中的细菌总量又同时最大限度的保护牛奶中原来的营养，是全世界乳品企业一直努力的方向。