活性包装在肉类保鲜中的应用

活性包装是一种新型的食品包装体系，是一种非常具有挑战性的技术，对肉及肉制品货架期的延长及食品安全有着重大的影响。活性包装的应用可以抑制微生物的生长，以提供更安全、可靠的肉制品。     

Combined use of modified atmosphere packaging and high pressure to extend the shelf-life of raw poultry sausage

The contribution of modified atmosphere packaging (MAP) in extending the shelf-life of high-pressure treated raw poultry sausages was examined by considering microbial and oxidative stability (TBARs) aspects. Raw poultry sausages packaged under air or modified atmosphere (50% CO₂–50% N₂) were pressurized at 500 MPa during 5 min at a maximum temperature of 10.5 °C, subsequently allowed to refrigerated storage during 22 days. During storage, samples were tested at time intervals for headspace gas composition, pH, TBARs, Aerobic Mesophilic Counts (AMC) and Lactic Acid Bacteria (LAB) counts. The high pressure treatment could represent an efficient means of extending the microbiological shelf-life, insofar as it reduced and stabilized the AMC and LAB counts. However, the MAP did not further improve the microbial quality. But, still, by limiting lipid oxidation, it remains an essential technology for the control of the organoleptic quality, another important characteristic to consider in shelf-life determinations.Industrial relevanceRaw poultry meat and especially raw ground poultry meat, such as raw poultry sausages are highly perishable.Economic challenges and busier lifestyles have consumers seeking out products with longer and longer shelf-lives. Manufacturers have to respond to this demand by improving processes. The use of alternative preservation techniques such as high hydrostatic pressure represents a promising strategy to enhance the shelf-life of meat products and is preferred by consumers to addition of food additives. Modified atmosphere packaging is largely used to extend the shelf-life of processed meat products. Manufacturers may question the relevance of maintaining MAP while introducing a new step of high pressure treatment in their process. This study showed that MAP significantly reduced lipid oxidation. In that way, MAP remains necessary to maintain organoleptic quality of pressurized raw poultry sausages.     

Nisin延长低脂再制干酪保质期的应用

Nisin已广泛应用于食品保质期的研究中,本试验研究在贮存过程中,Nisin对低脂再制干酪细菌、肠杆菌、霉菌和酵母菌的抑菌效果及pH的变化。在低脂再制干酪样品中,空白样品贮藏到5个月时,样品变质不可食用,添加0.2%、0.3%Nisin的样品到6个月时,细菌总数、肠杆菌、酪霉菌和酵母菌合格,而添加0.2%Nisin、0.3%Nisin抑菌效果差异不显著,因此添加0.2%Nisin为宜。随着贮藏期时间的增加,pH显著增加。     

Predictive modelling of the recovery of Listeria monocytogenes on sliced cooked ham after high pressure processing

This study examined bacterial recovery on sliced cooked ham that was inoculated with Listeria monocytogenes, treated by high pressure processing (HPP) and then stored at 10 degrees C for 70 days. The number of L. monocytogenes on the ham inoculated with 5 log(10) CFU/g was initially reduced by HPP at 500 MPa for 10 min to below the detectable level (10 CFU/g). However, the bacterial count gradually increased during storage, and exceeded the initial inoculum level at the end of the 70-day period, having risen by 7-8 log(10) CFU/g. A novel predictive model was therefore developed to estimate the recovery of L. monocytogenes during storage after HPP. Recovery of L. monocytogenes was defined as the detection of >10(2) CFU/g bacteria, in view of the relevant food safety objectives of L. monocytogenes. At each 14-day sampling session, the ham was scored as either 1 or 0 indicating bacterial recovery or no bacterial recovery, respectively. The data were then subjected to a simple linear logistic regression model, which provided a good fit as indicated by the performance statistics. Using this model, we estimated the minimum HPP conditions necessary for the required storage periods. Additionally, as the developed model was based on logistic regression, the probability of the recovery of L. monocytogenes during storage after HPP was estimated. Our model not only calculated the appropriate shelf life and process conditions, but also provided a method for evaluating the risk of the recovery of pathogenic bacteria during storage.     

延长酸奶保质期的研究进展

酸奶是一种富含营养且具有保健功能的发酵乳制品,但因其含有活性乳酸菌而保质期较短。影响酸奶保质期的主要因素有两方面,即微生物的污染和发酵后酸化。基于以上原因,文章分析了污染微生物的种类及造成的危害,从酸奶加工工艺设备和包装措施的改进以及发酵剂菌种的选育等角度综述了延长酸奶保质期的措施,并为长保质期酸奶的开发应用提供理论基础。 关键词：中图分类号：TS252.54 文献标识码：A 文章编号：0254-5071（20１5）04-0008-05 doi:     

Effect of high pressure on fresh cheese shelf-life

The effect of high pressure (HP; 300 and 400 MPa for 5 min at 6 °C) on physico-chemical, microbial, color, texture and sensorial characteristics of starter-free fresh cheeses stored at 4 and 8 °C was studied. Physico-chemical parameters considered were total solids, fat, total protein, pH, whey loss and water activity. The microbiological quality was studied, on cheeses stored at 4 and 8 °C, by enumerating aerobic mesophilic bacteria, lactococci, psychrotrophic bacteria, Enterobacteriaceae, Escherichia coli, molds and yeasts. Cheeses treated at 300 and 400 MPa, stored at 4 °C, presented a shelf-life of 14 and 21 days, respectively, compared to untreated control cheese, which presented a shelf life of 7 days. On the other hand, HP treatments modified the texture (more firm) and color (more yellow) compared to control cheeses. These changes were detected by instrumental and sensory analysis.     

Orange juices enriched with chitosan: Optimisation for extending the shelf-life

Optimisation of the incorporation of chitosan in orange juice was accomplished by the evaluation of quality and nutritional markers. Response surface methodology was applied to obtain quadratic and second degree response surface model equations. The analyses showed that increases in chitosan concentration extended the quality of the orange juice significantly (p < 0.05), reducing enzymatic and non-enzymatic browning and controlling the spoilage during the storage time; however, concentrations > 1 g L^− 1 produced a significant (p > 0.05) reduction in the concentrations of ascorbic acid and carotenoids associated with the positive charge of chitosan and its ability to flocculate and coagulate negatively charged substances. Also, concentrations > 1 g L^− 1 were scored as unacceptable for the sensory panel due to an increase in bitterness. The study recommends the use of chitosan at concentrations up to 1 g L^− 1 to extend quality and preserve ascorbic acid and carotenoids during storage time of fresh orange juice, thus avoiding the use of standard thermal treatments which produces a negative impact on the nutritional value.

Industrial relevance

One of the major problems of fresh orange juice is its limited shelf-life. Spoilage and quick degradation of vitamins are two of the most important causes of quality loss during the shelf-life of this product. Moreover, the U. S. Food and Drug Administration issued a warning to consumers against drinking unpasteurised orange juice products because of the potential contamination with Salmonella typhimurium and its association with an outbreak of human disease caused by this organism [FDA issues nationwide health alert on Orchid Island unpasteurised orange juice. Products Recalls, Market Withdrawals and Safety Alerts.]. The main objective of this study was the study of chitosan as a natural preservative for extending the shelf-life of orange juice and as an alternative to pasteurisation.     

高压加工技术在水产品中的应用

高压加工技术是目前食品工业中热门加工技术之一,它能够保持食品的天然风味,但这种方法目前在水产品中应用还不是很多,本文综述了高压加工技术对水产品中微生物和水产品品质的影响。     

生物活性包装技术在肉制品保鲜中的应用

为抑制鲜肉及其制品表面腐败菌和病原菌的生长与繁殖,生物活性包装技术的运用前景广阔.与抗菌化合物直接与食品混合法不同,生物活性包装是将抗菌刑加入到包装材料中,通过蒸发平衡或迁移过程作用于内制品表面的微生物,延长产品的货架期,提高肉制品的食用安全性.目前主要的生物活性包装技术有:生物活性试剂生成剂小袋与肉制品一起包装,生物活性物质直接混合到包装材料中,将生物活性物质涂或喷到包装材料的表面,具有成膜特性的抗菌大分子以及生物活性可食性膜的使用.     

Development of shelf-life kinetic model for modified atmosphere packaging of fresh sliced mushrooms

Mushrooms are highly perishable and their shelf-life depends on processing, package properties and environmental conditions during storage and distribution. The aims of this work were to evaluate the effect of temperature and number of film perforations on quality and develop shelf-life kinetic model for a modified atmosphere packaging (MAP) for sliced button mushrooms. Sliced mushrooms were packed in a tray, covered with cellophane film, and stored for 7 days at four levels of temperature (0, 5, 10, and 15 °C) and three levels of perforations at each temperature ranging the number of perforations from 1 (58 perforations per m²) to 6 (349 perforations per m²). Headspace gas composition and quality parameters (weight loss, pH, firmness and colour) were measured throughout the storage period. Increasing the storage temperature required an increase of the number of perforations in order to obtain the optimum MAP conditions. Temperature had a significant effect (p < 0.05) on quality of sliced mushrooms. Firmness was identified as a critical quality parameter; therefore, a kinetic model was developed to describe the influence of temperature on firmness and predict shelf-life of sliced mushrooms. Fresh sliced mushrooms had a shelf-life of 1, 2, 4, and 7.5 days at 15, 10, 5, and 0 °C, respectively, under optimum MAP conditions.     

Effect of high pressure processing on the safety,shelf life and quality of raw milk

High pressure processing (HPP) was investigated as an alternative to standard raw milk processing. Different pressure levels (400–600 MPa) and exposure times (1–5 min) were tested against artificially inoculated pathogenic E. coli, Salmonella and L. monocytogenes. HPP effectively inactivated bacterial concentration by 5 log CFU/ml. The most effective HPP conditions in terms of pathogen reduction were subsequently utilised to determine the effect of pressure on microbiological shelf life, particle size and colour of milk during refrigerated storage. Results were compared to pasteurised and raw milk. HPP (600 MPa for 3 min) also significantly reduced the total viable counts, Enterobacteriaceae, lactic acid bacteria and Pseudomonas spp. in milk thus prolonging the microbiological shelf life of milk by 1 week compared to pasteurised milk. Particle size distribution curves of raw, pasteurised and HPP milk, showed that raw and HPP milk had more similar casein and fat particle sizes compared to pasteurised milk. The results of this study show the possibility of using HPP to eliminate pathogens present in milk while maintaining key quality characteristics similar to those of raw milk.     

超高压处理对烟熏火腿色泽、游离脂肪酸及脂肪氧化指标的影响

为探究超高压处理手段应用于烟熏火腿保鲜的同时是否能够保持产品原有的品质,本实验以400MPa和600MPa的压力在常温下(22℃)对切片真空包装后的烟熏火腿进行10min超高压处理,与未经超高压处理产品(NT组)作对照,4℃下贮藏,研究了超高压前后产品色泽、游离脂肪酸以及脂肪氧化指标的变化。结果表明:超高压处理组样品能够保持原有鲜亮色泽,而未经超高压处理组出现明显褪色;超高压处理后样品的各游离脂肪酸含量变化不显著;贮藏初期超高压处理组与未经超高压处理组样品TBARS值都没有显著变化,而随贮藏期延长,高压处理组样品TBARS值比未处理组略有上升,但TBARS最大值小于0.5mg/100g肉样。实验所用超高压处理条件不会引起真空包装烟熏火腿色泽、游离脂肪酸指标的显著变化,能够较好地保持产品原有游离脂肪酸组成及鲜亮色泽,也不会造成产品的氧化酸败。     

Hyperbaric cold storage versus conventional refrigeration for extending the shelf-life of hake loins

Today, extending the shelf-life of fish, while retaining the organoleptic properties of the product, is still a challenge. To compare the effectiveness of conventional and hyperbaric cold storage in preserving fish quality, we stored Cape hake loins at 5 °C, both at atmospheric pressure and at 50 MPa. After 7 days of storage, microbial counts and total volatile basic-nitrogen content in conventionally refrigerated samples exceeded the limits recommended for consumption. By contrast, hyperbaric cold storage maintained these parameters unaltered, although it produced drip losses close to 5% and increased the shear resistance and whiteness of the raw samples by 44% and 9%, respectively. Nevertheless, after cooking, weight losses were less than half of those of the control loins and whiteness differences disappeared. Consequently, the sensorial analysis could only find moderate differences between the samples before and after hyperbaric storage. These results clearly prove that hyperbaric cold storage was more efficient than conventional refrigeration for the preservation of hake loins.Industrial relevanceHyperbaric cold storage opens interesting new doors for the fish-processing industry. Thus, it could be employed in different sections of the cold chain: on board, immediately after caught; at the food industry, during processing; on ship or trunk transport for long-distance markets; at school or hospital kitchens; at restaurants; or even at home. The increased cost resulting from hyperbaric storage should be overcome by an extended shelf life of a high-quality product.     

The effect of NaCl-free processing and high pressure on the fate of Listeria monocytogenes and Salmonella on sliced smoked dry-cured ham

NaCl is an important multifunctional ingredient applied in dry-cured ham elaboration. However, its excessive intake has been linked to serious cardiovascular diseases causing a recent increase in the development of reduced salt products. In the present study Listeria monocytogenes and Salmonella, food-borne pathogens which can cross-contaminate post processed products, were spiked with < 100 CFU/g on slices of both standard (S) and NaCl-free processed (F) (elaborated with KCl + potassium lactate instead of NaCl) smoked dry-cured ham. Although L. monocytogenes and Salmonella counts decreased faster in S ham, pathogens were present in both types of non-pressure treated ham during the entire refrigerated storage period (112 days). Pressurisation at 600 MPa for 5 min caused the elimination of both pathogens in S ham after 14 days. In contrast, Salmonella and L. monocytogenes were present in F ham until days 28 and 56, respectively, indicating that the NaCl-free processed dry-cured ham had lower stability than standard smoked dry-cured ham.     

Effect of high pressure processing on the quality of squid (Todarodes pacificus) during refrigerated storage

The influence of high pressure processing (HPP) on the inhibition of trimethylamine-N-oxide demethylase (TMAOase) activity and off-odour production in squid treated at 300 MPa for 20 min was investigated during 12 days of refrigerated storage. TMAOase activity of raw squid (21.5 nkat/g) was significantly decreased to approximately 5 nkat/g after 20 min of HPP. The production of dimethylamine (DMA) in HPP-treated squid for 20 min was significantly decreased to 0.31 μmol/g after 12 days of storage. The decrease in DMA was correlated with the decrease in TMAOase activity. At 300 MPa, the number of total aerobic bacteria in squid was reduced by 1.26 log units after 20 min of HPP. The HPP-treated samples effectively reduced the amount of trimethylamine (TMA). Therefore, the HPP could be used as a promising alternative technology to retard the quality deterioration of squid by inhibiting TMAOase activity and microbial growth.     

超高压技术在酱牛肉保鲜中的应用

为探究超高压技术应用于肉制品保鲜中的可行性,对真空包装的酱牛肉采用600MPa,5、10、15min的超高压处理并与热处理(85～90℃,10min)及未处理组对照,分别在0、2、4、6、8周测定了4℃冷藏条件下的菌落总数、乳酸菌数以及pH、色泽、脂肪氧化值、挥发性盐基氮等理化指标。结果表明,高压处理能够显著降低酱牛肉的初始菌数(p<0.05),抑制细菌的生长,5min和10、15min组分别在第4、第6周超过80000cfu/g;处理组均出现脂肪氧化值升高的现象,高压组pH略有升高,热处理组储藏末期红度值显著降低(p<0.05),其他理化指标没有显著变化。综合考虑,超高压技术可用于真空包装酱牛肉的保鲜中,延长产品货架期。     

超高压技术在贝类脱壳加工中的应用

贝类是现代备受青睐的海产品,由于其营养丰富而受到消费者的喜爱,贝类的脱壳问题是加工过程的关键。超高压脱壳是一种新兴的食品加工技术,它既可以完成脱壳过程,又可以减少贝肉中的有害微生物,是现代比较热门和常用的脱壳技术。通过对目前脱壳技术的应用状况进行研究和分析,发现利用超高压技术对贝类进行脱壳处理,不仅可以获得较高的脱壳率,还可以获得完整的贝肉,并保持产品的感官品质和营养价值,延长产品的货架期,是一种比较适合于贝类脱壳的加工技术。