不同包装条件下冷却肉品质变化及腐败菌相研究

为寻找冷却猪肉合理的包装方式,延长货架期,将猪后腿肉分别进行托盘包装、真空包装、高氧气调包装（20%CO₂+80%O₂）和低氧气调包装（65%CO₂+35%O₂）处理,并以无包装组为对照,测定样品在4℃贮藏过程中挥发性盐基氮（TVB-N）值、色差值a*、丙二醛（MDA）值、微生物菌落（菌落总数、假单胞菌菌落数和热杀索丝菌菌落数）和感官评分。结果表明:无包装和托盘包装冷却猪肉货架期不超过4 d,高氧气调包装（20%CO₂+80%O₂）货架期为6 d,真空包装和低氧气调包装（65%CO₂+35%O₂）货架期长达9 d。真空和气调包装均有利于延长冷藏猪肉货架期,但真空包装使肉呈暗红色。气调包装中O₂和CO₂的含量影响肉的品质,高氧气调包装有利于好氧菌假单胞菌和热杀索丝菌的生长繁殖,同时促进脂质氧化,但可以很好维持肉色,低氧气调包装（65%CO₂+35%O₂）可以抑制细菌的生长和脂肪氧化。综合各项评判结果,得到最佳包装方式为低氧包装（65%CO₂+35%O₂）。      

Microbial and sensory quality of vegetables for soup packaged in different atmospheres

Fresh prepacked vegetables for soup have become very popular on the Italian market, since they are already peeled, cut, washed and ready-to-use. The packaging and the modified atmosphere can prolong their shelf-life and maintain their hygienic, physicochemical and sensory characteristics during storage at + 4°C. The hygienic and sensory quality was evaluated by analysing microbial growth and atmosphere composition at the moment of packaging and at the end or the shelf-life of vegetables prepacked in air on under modified atmospheres, and by determining the browning or blackening of parsley and the loss of carrot exudates. A large number of different groups of microorganisms was found in raw vegetables. In spite of this high starting concentration of microbial flora, the prepackaging systems investigated did not seem to significantly influence their growth during vegetable storage at +4°C. No pathogenic microorganisms were isolated from the prepackaged vegetables. The hygienic quality was similar in all packaging systems used. However, the vegetables packaged in perforated. film kept their sensory characteristics better than those packaged in air or under a modified atmosphere.     

不同CO_2比例气调包装对冰温贮藏鲜罗非鱼片品质的影响

采用不同的气体组成A(50%CO2/10%O2/40%N2)、B(60%CO2/10%O2/30%N2)、C(70%CO2/10%O2/20%N2)和空气(对照)分别包装鲜罗非鱼片,在-0.5±0.2℃贮藏,研究不同CO2比例气调包装在冰温贮藏条件下对鲜罗非鱼片品质的影响。实验结果表明,罗非鱼的冰点在-0.8～-0.9℃之间,贮藏7d以后,与对照相比,气调包装能显著抑制产品细菌菌落总数和嗜冷菌数的增长(p<0.05)。在冰温贮藏期间,气调包装样品的肉汁渗出率要高于对照产品,随着贮藏时间的延长,四组样品的TVB-N值均有不同程度的上升,但是贮藏10d以后,对照的TVB-N值开始高于三种气调包装样品;包装方式对产品pH的影响并不明显,但是对照的pH随着贮藏时间的延长基本呈上升趋势,四种处理的罗非鱼片在整个贮藏期间TBA值几乎都没有变化。三组CO2比例气调包装样品在贮藏期间的品质差异并不明显,但是在冰温条件下,气调包装处理能明显延长鲜罗非鱼片的货架期。     

包装方式对四角蛤蜊卤制风味产品贮藏品质的影响

目的：研究不同包装方式对其贮藏期品质的影响。方法 对四角蛤蜊卤制风味产品进行普通包装、真空包装、30% CO2+70% N2、50% CO2+50% N2、30% N2+70% CO2气调包装,并在4 ℃贮藏条件下,测定菌落总数、质构特性、色差、TVB-N值、风味特性等理化指标,选择最佳的包装方式。结果 普通包装样品在第3 d、真空包装组样品在第6 d时菌落总数超标,而气调包装组的货架期可达12 d左右。气调包装组的硬度、弹性、咀嚼性的下降程度都低于普通包装和真空包装组,气调包装的护色效果也优于其他两组。气调包装对TVB-N值、TBA值、pH值变化的延缓作用明显优于真空包装和普通包装。结论 不同包装方式对四角蛤蜊卤制风味产品贮藏品质的保持能力依次为气调包装、真空包装、普通包装,其中50% CO2+50% N2气调包装保鲜效果最佳,能显著延长产品货架期。     

CO气调包装对冷却猪肉货架期及色泽的影响

冷却猪肉采用不同浓度CO气调包装和真空包装,(4±1)℃下贮藏,研究CO气调包装对其货架期和色泽的影响。结果表明,CO气调包装肉在贮藏到第25天时,TVB-N值已超过0.15mg/g,细菌总数超过106cfu/g,与真空包装相比,并不能显著地延长肉的货架期;CO气调包装肉在贮藏期中一直保持稳定的鲜红色,不同浓度CO气调包装对肉色无显著性差异,真空包装肉呈褐色或暗紫色。     

包装方式对牛排贮藏期间微生物数量和演替的影响

为研究包装方式对牛排贮藏期间的品质、微生物数量和演替的影响,牛排分别采用50% O2气调包装（50% O2＋30% CO2＋20% N2）和真空包装在0～4 ℃下贮藏21 d,并检测贮藏期间pH值、肉色、微生物数量和微生物多样性。结果表明：50% O2气调包装组比真空包装具有更好的护色效果;贮藏21 d时,与真空包装组相比,气调包装组菌落总数、乳酸菌数和假单胞菌数降低;两种包装的微生物多样性均随时间延长呈现先升高后降低的趋势,且真空包装牛排比50% O2气调包装牛排具有更复杂的微生物多样性;牛排的初始微生物主要由不动杆菌属、苍白杆菌属、栖热菌属和金黄杆菌属组成,随着贮藏时间的延长,肉食杆菌属逐渐成为真空包装牛排的优势菌群,而环丝菌属、沙雷氏菌属和乳杆菌属则成为50% O2气调包装牛排的优势菌群;贮藏7～14 d是牛排中微生物种类产生变化的关键时间点;相比于真空包装牛排,50% O2气调包装牛排中的微生物群落具有更低的糖代谢和更高的蛋白质代谢能力。本研究结果明确了不同贮藏方法下牛排的品质变化和微生物的演替规律,为定向抑制牛排中的微生物、延长产品货架期提供了参考。     

Biodiversity and dynamics of the bacterial community of packaged king scallop (Pecten maximus) meat during cold storage

The microbial biodiversity and dynamics of king scallops meat and coral during cold storage (cold chain rupture: 1/3 storage time at 4 °C followed by 2/3 at 8 °C), was assessed by combining culture-dependant and -independent methods. Products were packaged as follows: aerobic, vacuum packed and 3 different CO₂/N₂ modified atmospheres and the impact of these conditions on the microbial communities was assessed. Results indicated that under air (current packaging condition), the dominant species corresponded to Brochothrix thermosphacta, Pseudomonas spp. and Shewanella spp. These species have regularly been associated in the literature with food (especially seafood), and product spoilage. Moellerella wisconsensis was the only species detected on VRBG medium, however, its impact on the food product is unclear. Packaging conditions influenced the ecosystem equilibrium and biodiversity. Except for day 8, the lowest counts for all studied flora were observed for modified atmosphere packaging (MAP) containing >80% CO₂. Moreover, in these conditions, higher biodiversity by Temporal Temperature Gradient Gel Electrophoresis (TTGE) and the non-detection of specific flora (i.e. Pseudoalteromonas haloplanktis) were observed. At day 8, scallops packaged using these conditions were still acceptable from a sensorial point of view (odour), although the initial load of the king scallop was high (total psychrotrophic flora reached 5.5 log CFU/g).     

Effects of storage under a modified atmosphere on the microbiological and organoleptic qualities of ground beef prepared from pasteurized manufacturing beef

A 40‐kg lot of manufacturing beef, i.e. meat used for the production of ground beef products, was collected at a beef packing plant. The lot was divided into two batches. One batch was pasteurized by immersion in water at 85 °C for 60 s, the other batch was not pasteurized. Both batches were then ground. The ground meat was packed in overwrapped trays, which were master packaged under a modified atmosphere of 70% O₂ : 30% CO₂. The master packs were stored at 2 °C for up to 12 days. At the time of pack preparation and at 2‐day intervals, a master pack containing pasteurized and another pack containing unpasteurized meat, were opened and retail packs from each master pack were displayed at 4 °C for 3 days. Samples for microbiological analysis were obtained at the times of opening master packs and at the end of display. Displayed meat was assessed daily for colour, discoloration and retail appearance, and for odour intensity and acceptability at the end of display. After either a period of storage or a period of storage and display, the numbers of bacteria recovered from pasteurized meat were less than the numbers recovered from unpasteurized meat. The colour of pasteurized meat was perceived as being paler than that of unpasteurized meat, but discoloration was similar or less, and retail appearance was similar or better for pasteurized than unpasteurized meat at all times. The odours of displayed, pasteurized meat were generally somewhat less intense and more acceptable than those of unpasteurized meat. The findings indicate that pasteurization of manufacturing beef to improve the microbiological safety of ground beef provides a product of acceptable appearance and enhanced stability during storage under a modified atmosphere and subsequent display in air.     

Behavior of flavonols and carotenoids of minimally processed kale leaves during storage in passive modified atmosphere packaging

Minimally processed kale leaves were packed in passive modified atmosphere and stored at 3 conditions: 1 °C in the dark and 11 °C with or without light exposure. The products were evaluated during storage in terms of headspace gas composition, sensory attributes, flavonol, and carotenoid contents. The sensory quality decreased slightly during 17 d at 1 °C in the dark. At 11 °C, the vegetable shelf life was predicted to be 6 d in the dark and 3 d with light. Quercetin and kaempferol were stable during storage for 15 d at 1 °C in the absence of light. At 11 °C in the dark, quercetin was stable during 10 d, increasing slightly on the 8th day. Kaempferol decreased up to the 5th day but increased on the 8th day, decreasing again on the 10th day. After 5 d at 11 °C under light, the flavonol levels were significantly higher than those of the initial values. Neoxanthin and violaxanthin did not change significantly after 15 d at 1 °C in the dark. Lutein and β-carotene, however, decreased 7.1% and 11.3%, respectively. At 11 °C in the dark, neoxanthin, violaxanthin, lutein, and β-carotene decreased 16.1%, 13.2%, 24.1%, and 23.7% after 10 d, respectively. At 11 °C under light, neoxanthin and lutein had a slight increase while violaxanthin and β-carotene decreased 23.1% and 16.5% after 5 d. Practical Application: Passive modified atmosphere packaging together with refrigeration can extend the shelf life of minimally processed kale, retaining the health-promoting compounds, flavonols and carotenoids. Quercetin, kaempferol, neoxanthin, and violaxanthin are stable and lutein and β-carotene slightly reduced.     

Production of biogenic amines by lactic acid bacteria and enterobacteria isolated from fresh pork sausages packaged in different atmospheres and kept under refrigeration

The occurrence of in vitro amino acid activity in bacterial strains associated with fresh pork sausages packaged in different atmospheres and kept in refrigeration was studied. The presence of biogenic amines in decarboxylase broth was confirmed by ion-exchange chromatography and by the presence of the corresponding decarboxylase genes by PCR. From the 93 lactic acid bacteria and 100 enterobacteria strains analysed, the decarboxylase medium underestimates the number of biogenic amine-producer strains. 28% of the lactic acid bacteria produced tyramine and presented the tdc gene. All the tyramine-producer strains were molecularly identified as Carnobacterium divergens. Differences on the relative abundance of C. divergens were observed among the different packaging atmospheres assayed. After 28 days of storage, the presence of argon seems to inhibit C. divergens growth, while packing under vacuum seems to favour it. Among enterobacteria, putrescine was the amine more frequently produced (87%), followed by cadaverine (85%); agmatine and tyramine were only produced by 13 and 1%, respectively, of the strains analysed. Packing under vacuum or in an atmosphere containing nitrogen seems to inhibit the growth of enterobacteria which produce simultaneously putrescine, cadaverine, and agmatine. Contrarily, over-wrapping or packing in an atmosphere containing argon seems to favour the growth of agmatine producer-enterobacteria. The production of putrescine and cadaverine was associated with the presence of the corresponding amino acid decarboxylase genes. The biogenic amine-producer strains were included in a wide range of enterobacterial species, including Kluyvera intermedia, Enterobacter aerogenes, Yersinia kristensenii, Serratia grimesii, Serratia ficaria, Yersinia rodhei, Providencia vermicola and Obesumbacterium proteus.     

Characteristics of pigment composition and colour value by the difference of harvesting times in Korean red pepper varieties (Capsicum annuum, L.)

The main pigments of Capsicum annuum cv. Hanbando and Dabotop in dried red fruits were capsanthin, zeaxanthin, beta‐cryptoxanthin and beta‐carotene. Total carotenoid contents were twice as high at the fourth harvest compared with the second harvest in both varieties. The ratios of capsanthin to yellow fraction were above 1.0 in Hanbando and below 1.0 in Dabotop. Zeaxanthin content at the third harvest was about three times higher than at the second harvest in Dabotop. ASTA colour values harvested in the second, third and fourth weeks were 114, 152 and 178 in Hanbando and 115, 137 and 140 in Dabotop. Hue value of Hanbando was below 1.0 at all harvests and that of Dabotop was above 1.0 at the second and fourth harvests. The comparison of the C* values of two varieties revealed that Hanbando had the most vivid redness at the fourth harvest, whereas Dabotop was most vivid at the second harvest.     

冷鲜猪肉在贮藏过程中生物胺含量变化及不同包装方式对生物胺含量变化的影响研究

目的 研究冷鲜猪肉在35℃下贮藏过程中生物胺的变化情况, 以及不同包装方式(高氧气调包装、高氧气调包装结合隔热材料、真空包装和真空包装结合隔热材料)对冷鲜猪肉贮藏过程中生物胺变化的影响。方法 将新鲜猪肉胴体快速冷却后切割, 按照不同包装方式分组包装, 以无包装为对照组, 在35℃下贮藏, 于0、12、24、36、48、60 h对96份样品中生物胺含量和种类进行检测, 分析不同包装条件下样品生物胺变化情况。结果 精胺和亚精胺在不同包装方式下0~60 h内均有检出; 腐胺和尸胺在4种包装方式和无包装方式下的含量始终较高。与对照组相比, 真空包装腐胺和尸胺检出时间延缓了24 h, 组胺和酪胺检出时间延缓了12 h; 在真空包装结合了隔热材料之后, 腐胺、尸胺、组胺和酪胺的检出时间延缓了12 h。与真空包装比, 高氧气调包装组胺始终未检出, 腐胺、尸胺和酪胺的检出时间延缓了12 h, 且含量更低, 在高氧气调包装结合了隔热材料之后, 这3种生物胺的检出时间进一步延缓12 h。结论 精胺和亚精胺是冷鲜猪肉中天然存在的生物胺; 腐胺、尸胺和酪胺是冷鲜猪肉腐败过程中产生的主要生物胺种类, 且随着贮藏时间的延长, 其含量显著增加, 其中腐胺和尸胺含量较高, 是影响冷鲜猪肉质量安全的主要生物胺。真空包装和高氧气调包装均能有效抑制生物胺的形成, 就包装方式而言, 相较于真空包装, 高氧气调包装能更有效地抑制生物胺的产生, 就有无隔热材料而言, 结合隔热材料能更有效地抑制生物胺的产生。     

Comparison of ascorbic acid and sodium erythorbate: Effects on the 24h display colour of beef lumbar vertebrae and longissimus lumborum packaged in high-oxygen modified atmospheres

Sodium erythorbate and ascorbic acid were compared as a means to stabilize surface colour of bone-in beef steaks in high-oxygen modified atmosphere (80% oxygen and 20% carbon dioxide). Bone-in strip loins (n = 8) were fabricated into 1.9 -cm thick steaks, of which both the lumbar vertebrae and longissimus lumborum were topically treated with either ascorbic acid or sodium erythorbate (0, 0.05, 0.1, 0.5, 1.0, or 1.5%, wt/wt basis). Colour (L^∗a^∗b^∗) was evaluated before treatment and 24 h after packaging (display at 1 °C). Sodium erythorbate was as effective as ascorbic acid for inhibiting vertebrae discolouration (P > 0.05). Either reducing agent at 0.5, 1.0, or 1.5% improved (P < 0.05) vertebrae redness (compared with 0%, 0.05% and 0.1%). No detrimental effects on muscle colour were observed. When selecting antioxidants intended for bone-in beef steaks displayed in high-oxygen packaging, sodium erythorbate may be a cost effective substitute for ascorbic acid.     

Survival of Salmonella enteritidis and changes in pH and organic acids in grated carrots inoculated or not with Lactobacillus sp and stored under different atmospheres at 4 °C

The fate of Salmonella enteritidis in grated carrots stored in air, modified atmosphere and vacuum at 4 °C was investigated with the coexistence or not of Lactobacillus sp. The population of Salmonella survived in all cases despite the presence of Lactobacillus and irrespective of the size of its inoculum. Lactic acid bacteria grew in all cases and a pH reduction was noted in all samples inoculated with Lactobacillus sp, while no such reduction occurred in sterile carrot tissue inoculated or not with S enteritidis. Sterile carrots exhibited minimum organic acid profile alterations compared to samples inoculated with Lactobacillus sp. Among these acids, lactate production was favoured under reduced oxygen conditions, in contrast to acetic acid, whose production required the presence of oxygen. These acids may act as an additional hurdle to control this pathogen under both aerobic and modified atmosphere packaging storage conditions. © 2002 Society of Chemical Industry     

Antioxidant effect of rosemary,borage, green tea,pu‐erh tea and ascorbic acid on fresh pork sausages packaged in a modified atmosphere: influence of the presence of sodium chloride

Fresh pork sausages formulated with and without salt, and with antioxidant mixtures containing either rosemary extract, green tea powder, pu‐erh tea infusion or borage meal and their mixtures with ascorbic acid, were packaged in an atmosphere containing four parts O₂ with one part CO₂ (v/v) and stored in the dark for 20 days. In a series of three experiments, the following parameters were measured at 4‐day intervals: instrumental colour (CIE L* and a*), thiobarbituric acid reactive substances (TBARS), aerobic psychrotroph counts and sensory off‐odour and discolouration. NaCl caused a decrease of the L* value and promoted lipid oxidation, but it protected sausages from discolouration. Green tea powder, pu‐erh tea infusion and borage meal caused a strong inhibition of lipid oxidation, dependent on the concentration used, but they failed to protect sausages from colour loss, even in the presence of ascorbic acid. Rosemary extract plus ascorbic acid strongly inhibited lipid oxidation and therefore off‐odour formation, delayed sausage discolouration and inhibited microbial growth, extending the shelf‐life of salted fresh pork sausages by at least 4 days. Copyright © 2006 Society of Chemical Industry     

Effects of palm oil quality and packaging on the storage stability of dry vegetable bouillon paste

Vegetable bouillon paste, prepared by dry-mixing of pre-produced dry ingredients with addition of semisolid palm oil, was stored at the slightly elevated temperature of 40 °C for up to 12 weeks for comparing modified atmosphere packaging (MAP; oxygen concentration initially below 0.5%) packaging with free availability of oxygen in order to identify the mechanisms leading to quality degradation. An increased browning and increased formation of volatile compounds related to Maillard reactions and oxidation of secondary lipid oxidation products were observed for the vegetable bouillon paste stored without limiting the oxygen availability. The use of palm oil (kept liquid by heating to 50 °C for one week) was further found to promote quality degradation as compared to fresh palm oil when the availability of oxygen was not limited by the packaging of the vegetable bouillon paste. For modified atmosphere packaging, the effect of the quality of the oil on storage stability of the product was less pronounced.