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.     

牛肉冰温气调保鲜技术的研究

研究了以不同组合比例的CO2、O2、N2的气调包装,结合冰温（-1．5±1℃）贮藏的牛肉保鲜技术。以空气包装为对照,以牛肉的色差值、菌落总数、失水率、挥发性盐基氮、PH值为衡量指标,综合评价冰温气调保鲜牛肉的效果。研究结果表明,最佳的气调包装组分为10％O2,70％CO2和20％N2,在此条件下可以保鲜达28天;保鲜牛肉的PH值为6．09,挥发性盐基氮值为14．634mg／100g,菌落总数为3．7×10^4efu／g,色泽紫红,无异味。     

Thymol and modified atmosphere packaging to control microbiological spoilage in packed fresh cod hamburgers

A study on the use of mild technologies to produce packaged fish hamburgers was presented. In particular, the antimicrobial effect of some natural compounds (carvacrol, eugenol, thymol, green tea extract, rosemary extract, grapefruit seed extract and lemon extract), at various concentrations (500–10 000 ppm), was screened in vitro against the main fish spoilage micro‐organisms (Shewanella putrefaciens and Photobacterium phosphoreum). Lemon extract and thymol, in combination with modified atmosphere packaging, showed the greatest inhibition activity, therefore, thymol was subsequently used as an ingredient for producing fish hamburgers. Results pointed out that this combination is effective in controlling the growth of microbial species mainly involved in fresh fish spoilage; in particular, it significantly (P < 0.05) reduced the growth rate of bacterial population, performing about 4.8 log CFU g^?1 and 6.5 log CFU g^?1 reduction of the hydrogen sulphide producing bacteria and psychrotrophic aerobic specific spoilage organisms cell load, respectively, if compared with the control.     

Effect of lactate-enhancement, modified atmosphere packaging, and muscle source on the internal cooked colour of beef steaks

Earlier studies on lactate-mediated colour stability in beef did not address the possible influence on cooked colour. Our objective was to examine the effect of lactate-enhancement, muscle source, and modified atmosphere packaging (MAP) on the internal cooked colour of beef steaks. Longissimus lumborum (LL) and Psoas major (PM) muscles from 16 (n = 16) beef carcasses (USDA Select) were randomly assigned to 4 enhancement treatments (non-injected control, distilled water-enhanced control, 1.25% and 2.5% lactate), and fabricated into 2.54-cm steaks. Steaks were individually packaged in either vacuum (VP), high-oxygen MAP (HIOX; 80% O₂ + 20% CO₂), or carbon monoxide MAP (CO; 0.4% CO + 19.6% CO₂ + 80% N₂), and stored for 0, 5, or 9 days at 1 °C. At the end of storage, surface and internal colour (visual and instrumental) was measured on raw steaks. Steaks were cooked to an internal temperature of 71 °C, and internal cooked colour (visual and instrumental) was evaluated. Lactate-enhancement at 2.5% level resulted in darker (P < 0.05) cooked interiors than other treatments. Interior cooked redness decreased (P < 0.05) during storage for steaks in VP and HIOX, whereas it was stable for steaks in CO. Our findings indicated that the beef industry could utilise a combination of lactate-enhancement and CO MAP to minimise premature browning in whole-muscle beef steaks.     

气调包装对冷鲜羊肉保鲜效果的影响研究

研究了单组分气体及不同比例气体组分对鲜羊肉进行气调包装后,对贮藏期间影响品质因素的关键技术指标的影响。试验条件下最优气体配比为CO2比例为20%,O2比例为65%。在此配比条件下,既可以改善并维持冷鲜羊肉良好的鲜红色泽,也可以在贮藏期间保持鲜肉的pH值和TVB-N值在规定的范围内,对延长冷鲜羊肉的贮藏期和保持良好的品质起到了一定作用。     

气调包装对番石榴贮藏品质的影响

研究12℃时4%O2+5%CO2+91%N2的气调包装对番石榴贮藏品质的影响。与相同温度下未气调包装相比,气调包装能够延缓果实的软化,推迟果肉内过氧化物酶活性和还原糖含量的达峰时间,降低了VC和可滴定酸的分解速率,抑制了丙二醛的生成速率。结果表明,气调包装的番石榴保质期比未气调样品延长了一倍,其在番石榴贮藏保鲜中有一定的推广应用价值。     

不同气调包装对冷藏白鲢鱼片质量的影响

用不同的气调成分(50%O2/50%CO2、50%N2/50%CO2、50%CO/50%CO2)及空气(对照组)分别包装鲢鱼片,并在冷藏(4±2℃)条件下贮藏,研究不同的气调包装处理对鲢鱼片理化及微生物的影响。结果显示,随贮存期增加,气调包装能有效抑制需氧菌数、嗜冷性细菌及大肠菌群的生长;气调包装处理的pH比控制组低,但其汁液流失量较控制组高;所有包装的TVBN值及TBA值随贮存时间增加而上升,色泽则逐渐衰减。     

Effect of ageing prior to freezing on colour stability of ovine longissimus muscle

The effect of different ageing periods (0, 2 and 3 weeks at -1.5°C) of lamb loins (n=24) prior to freezing (9, 7 and 6 weeks at -18°C, respectively) compared to the aged-only (never frozen) lamb for 9 weeks postmortem on colour stability during display was assessed under high-oxygen modified atmosphere (HiOx-MAP; 80% O(2)) and oxygen permeable overwrap packaging conditions. The aged/frozen loins and aged-only loins in HiOx-MAP had similar (P>0.05) surface redness, colour intensity, and discolouration. Further, no significant difference found in shear force between the loins aged 3 weeks/frozen 6 weeks and the aged-only loins. However, more lipid oxidation (P<0.05) was found in the aged-only compared to the aged/frozen loins in HiOx-MAP throughout display. These results suggest that ageing loins prior to freezing would provide equivalent tenderness and colour stability, and better lipid oxidation stability compared to the aged-only loins under HiOx-MAP.     

活性气调包装对番木瓜品质的影响

研究了内含CO2吸附剂的活性气调包装对番木瓜综合品质的影响。与未加吸附剂的普通气调相比,活性气调包装能够降低番木瓜的氧气消耗率,推迟番木瓜果肉内多糖和还原糖的达峰时间,减少番木瓜的失水率,提高气调包装对番木瓜的保鲜效果,但对维生素C影响不显著。研究结果表明活性气调包装在番木瓜保鲜贮藏中具有一定的推广应用价值。     

High-pressure treatment of dry-cured Iberian ham. Effect on colour and oxidative stability during chill storage packed in modified atmosphere

Slices of dry-cured Iberian ham were pressurized at 200 and 400 MPa for 15 min and subsequently packed in two different modified atmospheres of 30% carbon dioxide or 30% carbon dioxide and 5% oxygen (both balanced with nitrogen). Non-pressurized ham slices were also packed in two different modified atmospheres and all packages were stored at 5 °C for 39 days in illuminated chill cabinets. Measurements of colour and oxidative stability were performed after 1, 18 and 39 days of storage. High-pressure treatments at the level of 400 MPa resulted in the highest value for the tristimulus lightness L ^*-parameter during storage, reaching the maximum values after 39 days. Redness, measured as the tristimulus a ^*-parameter, was affected by pressure treatment, since samples submitted to treatment of highest pressure had significantly lower initial red colour. Oxygen was found to have a detrimental effect on nitrosylmyoglobin content since the extractable content was significantly lower after 18 and 39 days of storage in the 5% oxygen atmosphere. The effect of high pressure on oxidative stability was statistically significant after 39 days of chill storage with slices pressurized at 400 MPa showing the highest content in TBARS. High-pressure treatment at 400 MPa resulted in discoloration and oxidative degradation of lipids in dry-cured Iberian ham during subsequent illuminated chill storage.     

充气包装对青菜冷藏品质的影响

充气包装已成为一种有效的延长小包装蔬菜货架期的保鲜技术。目的是选择最合适的环境气调贮藏包装青菜,研究贮藏在4℃,不同的气体浓度(空气对照组、10%CO2+20%O2+70%N2、10%CO2+5%O2+85%N2、10%CO2+1%O2+89%N2、5%CO2+5%O2+90%N2、15%CO2+10%O2+85%N2)对其感官品质、叶绿素、亚硝酸盐、可溶性固形物、电导率等指标的影响。结果表明:4℃下,延长青菜货架期和保持其营养品质的最佳的气体组成为10%CO2+5%O2+85%N2。     

Effects of dietary vitamin E supplementation and packaging on the colour stability of sliced pasteurized beef ham

The effect of supplementation of vitamin E (2025 IU animal⁻¹ day⁻¹) in the diet of beef bulls on the colour stability of pasteurized beef ham was studied. Control and enriched diets were provided for the last 136 days before slaughter. Pasteurized hams were manufactured from Mm. semitendinosus from eight animals per dietary group. Half of the samples of sliced ham from control (CON) and supplemented (SUP) bulls were packaged under vacuum (VAC) and half in low-oxygen modified atmosphere packs (FOG, gas mixture: CO₂/N₂=50/50). The packages were kept under constant illumination for 28 days at 8°C. During storage, the number of colony-forming units (CFU) reached a maximum of 5x10⁷ g⁻¹. The microflora was dominated by lactic acid bacteria. The supplementation with vitamin E showed no effect on microbial growth. Lipid oxidation was stable during storage. A significant difference between both dietary groups was detected for the decrease in the redness values during storage. Redness values of CON vacuum-packaged samples decreased (P < 0.01) with time, whereas those for the SUP products only tended to decrease. The redness values of FOG-packed ham were higher than those of VAC-packed ham at the end of the display period, irrespective of the dietary group. Overall, colour appeared to be more stable in the FOG-packed products than in the VAC-packed products. It can be concluded that dietary supplementation of bulls with vitamin E appears to offer only a minor improvement in colour stability over current feeding regimens when the Mm. semitendinosus are used to make cured, pasteurized ham-type products.     

调理配料对生鲜猪肉高氧MAP产品品质的影响研究

新鲜猪肉为原料,研究以食盐、复合香辛料、料酒添加量作为正交实验因素的生鲜调理猪肉在气调包装下的品质指标的变化。结果表明:与鲜肉相比,生鲜调理猪肉红度值提高,剪切力值与水分含量有小幅度上升,在4℃储藏过程中,生鲜调理猪肉色泽逐渐变暗(表现为a值下降),剪切力值呈现上升趋势,但货架期(5d)内生鲜调理猪肉的色泽与嫩度仍在可接受范围内,食盐与复合香辛料以及料酒含量对剪切力值的影响有显著交互作用(p<0.05)。综合正交实验直观分析及以剪切力值为目标函数的回归优化,最终得出配方为食盐:2%,香辛料:1%,料酒:7%。      

Effect of ripeness at processing on fresh-cut 'Flor de Invierno' pears packaged under modified atmosphere conditions

The effects of ripeness at processing and packaging conditions on respiration, microbiological stability as well as colour and firmness of fresh-cut 'Flor de Invierno' pears were evaluated throughout storage. Although a 2.5-kPa O₂ + 7-kPa CO₂ atmosphere led to an inhibition of ethylene synthesis and carbon dioxide production compared with non-modified atmosphere packaging, the more advanced the ripeness stage at processing, the higher the physiological activity and thus, the higher production of carbon dioxide, ethylene and ethanol. A 2.5-kPa O₂ + 7-kPa CO₂ atmosphere inhibited bacterial growth, yeast and mould proliferation in mature-green pears but fast microbial growth was observed especially on ripe pears, under both packaging conditions. In conclusion, the shelf-life of ripe pears was reduced by increased respiration response to processing and accelerated microbial spoilage. Instead, pears processed in a partially ripe stage were suitable for conservation while gathering desired sensory attributes. Therefore, for commercial purposes, a shelf-life of 10 days was suggested for partially ripe fresh-cut pears packaged under a 2.5-kPa O₂ + 7-kPa CO₂ atmosphere.     

Shelf-life of Domiati cheese under modified atmosphere packaging

The present study describes the effects of modified atmosphere packaging (MAP) on shelf-life extension, chemical, microbiological, and sensory properties of Domiati cheese. Five different MAP were studied [10% CO₂/90% N₂ (G1), 15% CO₂/85% N₂ (G2), 25% CO₂/75% N₂ (G3), 100% CO₂ (G4), and 100% N₂ (G5)]. Control samples were packaged in air (CA) and under vacuum. In both groups of cheeses, chemical analysis was significantly affected by MAP during cold storage. Ripening indexes were significantly affected by MAP during cold storage. Microbiological data showed that G4, followed by G5, were the most effective groups inhibiting the growth of total aerobic mesophilic and psychrotrophic bacteria, and yeasts and molds until the end of storage. Sensory evaluation was significantly affected by MAP and storage period, at 45 d CA cheese samples were judged as unacceptable. The best sensory properties were obtained in G5, G4, and G3 treatments, and recorded a relatively higher sensory evaluation scores. The best shelf-life extension was obtained in G5, G4, and G3 treatments.     

Effect of modified atmosphere packaging on microbial growth,quality and enzymatic defence of sanitiser washed fresh coriander

Fresh coriander samples were washed in an aqueous chlorine dioxide solution and stored in modified atmosphere packaging (MAP) with air (T0), 4%O₂ + 3%CO₂ + 93%N₂ (T1); 10%O₂ + 3%CO₂ + 87%N₂ (T2); 15%O₂ + 3%CO₂ + 82%N₂ (T3); 20%O₂ + 3%CO₂ + 77%N₂ (T4) at 4 °C for 14 days. After 14 days, the ascorbic acid contents in samples were 24.8 (T3), 22.4 (T4), 19.6 (T0), 18.2 (T2) and 8.8 (T1) mg/100 g; the total phenol contents were 59.9 (T3), 53.8 (T0), 50.1 (T4), 44.8 (T2) and 39.3 (T1) mg gallic acid/100 g; and the total chlorophyll contents were 1.60 (T3), 1.52 (T4), 1.05 (T2), 0.91 (T0) and 0.63 (T1) mg g^?1 respectively. T3 treatment resulted in the best colour maintenance, the least bacterial growth, and the highest activities of superoxide dismutase and catalase throughout the storage period as compared to others. The data revealed that the T3 MAP condition in combination of aqueous chlorine dioxide washing significantly (P < 0.05) maintained the quality and extended the shelf life of fresh coriander.     

高氧气调包装对鲜切胡萝卜的保鲜效果

研究了不同氧分压条件对鲜切胡萝卜保鲜效果的影响,评定其在贮藏过程中感官品质、呼吸强度、PPO、POD、PAL活性的变化。结果表明,40%氧气包装不适合鲜切胡萝卜贮藏保鲜。100%氧气包装的保鲜效果最好,可有效抑制鲜切胡萝卜呼吸强度以及PPO、POD、PAL的活性。60%、80%氧气包装的保鲜效果次之,但均可起到保鲜的作用。      

Effect of modified atmosphere packaging on the growth of spoilage microorganisms and Listeria monocytogenes on fresh cheese

Queso Fresco has a limited shelf life and has been shown to support the rapid growth of Listeria monocytogenes during refrigerated storage. In addition to improving quality and extending shelf life, modified atmosphere packaging (MAP) has been used to control the growth of pathogenic microorganisms in foods. The objectives of this study were to determine the effects of MAP conditions on the survival and growth of spoilage microorganisms and L. monocytogenes during storage of Queso Fresco manufactured without starter cultures. For L. monocytogenes experiments, cheeses were surface inoculated at ～4 log₁₀ cfu/g before packaging. Inoculated and uninoculated (shelf life experiments) cheeses were placed in 75-µm high-barrier pouches, packaged under 1 of 7 conditions including air, vacuum, or combinations of N₂ and CO₂ [100% N₂ (MAP1), 30% CO₂:70% N₂ (MAP2), 50% CO₂:50% N₂ (MAP3), or 70% CO₂:30% N₂ (MAP4), 100% CO₂ (MAP5)], and stored at 7°C. Samples were removed weekly through 35 d of storage. Listeria monocytogenes counts were determined for inoculated samples. Uninoculated samples were assayed for mesophilic and psychrotolerant counts, lactic acid bacteria, coliforms, and yeast and mold. In general, cheeses packaged under conditions consisting of higher contents of CO₂ had lower pH levels during storage compared with those stored in conditions with lower levels or no CO₂ at all. Similarly, the antimicrobial efficacy of MAP in controlling spoilage microorganisms increased with increasing CO₂ content, whereas conditions consisting of 100% N₂, vacuum, or air were less effective. Mean L. monocytogenes counts remained near inoculation levels for all treatments at d 1 but increased ～2 log₁₀ cfu/g on cheeses packaged in air, vacuum, and 100% N₂ (MAP1) conditions at d 7 and an additional ～1.5 log₁₀ cfu/g at d 14 where they remained through 35 d. In contrast, treatments consisting of 70% CO₂ (MAP4) and 100% CO₂ (MAP5) limited increases in mean L. monocytogenes counts to <1 log₁₀ cfu/g through 14 d and ～1.5 log₁₀ cfu/g by d 21. Mean L. monocytogenes counts increased to levels significantly higher than inoculation (d 0) on cheeses stored in MAP2 and MAP3 on d 21, on d 28 for MAP4, and on d 35 for cheeses stored under MAP5 conditions. Overall, significant treatment × time interactions were observed between air, vacuum, and MAP1 when each was compared with MAP2, MAP3, MAP4, and MAP5. These data demonstrate that packaging fresh cheese under modified atmospheres containing CO₂ may be a promising approach to extend shelf life while limiting L. monocytogenes growth during cold storage.     

含CO气调包装对冷却肉肉色的影响

以宰后冷却24h的猪背最长肌为材料,用四组含不同浓度CO的混合气体进行气调包装,于4±1℃下贮藏,分别在第0、5、1O、15、20天测定相关指标。结果表明：CO气调包装能明显改善肉色,并使冷却内在贮藏期中保持稳定的鲜红色。与无氧组相比,CO和O2的共同存在可以使冷却肉肉色更加自然。