The effect of modified atmosphere packaging with carbon monoxide on the storage quality of master-packaged fresh pork

Modified atmosphere packaging with carbon dioxide is effective for prolonging shelf-life of fresh meat. Addition of carbon monoxide to the system provides the advantage of enhancing meat colour. The study objective was to determine the effect of CO₂-MAP + 0.4% CO, vs. 100% CO₂-MAP, on the bacteriology and colour of retail-ready fresh pork stored for 8 weeks in a master-package system. Total plate counts were not affected and listeria was present on meat from both treatments. Colour was enhanced with the inclusion of CO, while no effect on lipid oxidation was observed. Use of CO in MAP provides sufficient storage life and product colour quality to permit shipment of fresh pork to distant markets. However, given the stable fresh colour of CO-treated meat and the lack of inhibition of pathogen growth by CO, there is concern that CO-MAP under certain conditions may pose a food safety risk.     

Effects of packaging method and storage time on the chemical, microbiological, and sensory properties of Turkish pastirma - A dry cured beef product

The effects of packaging method (aerobic packaging (AP), vacuum packaging (VP) or modified atmosphere packaging (MAP)), the form of pastirma (sliced or non-sliced) and storage time (0, 15, 30, 60, 90 or 120 days) on the chemical, microbiological and sensory properties of a Turkish pastirma were investigated. Overall, MAP preserved chemical, microbiological and sensory properties of Turkish pastirma better than AP or VP. Very high correlation coefficients (almost all >0.90) were observed between subjective quality parameters (sensory properties) and objective quality parameters (TBARS, hexanal content, L^*, a^*, and b^*), which suggests that sensory panel was able to determine the quality changes over storage time precisely. Based on the results of this study, MAP should be the preferred choice of packaging in order to preserve overall quality of Turkish pastirma and its implication for pastirma packaging may increase pastirma’s current share in the processed meat product market.     

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。     

Changes of yolk biogenic amine concentrations during storage of shell hen eggs

The RP-HPLC/UV method, using dabsyl derivatization, optimised for the determination of biogenic amines in egg yolk, was appropriate for quantification of putrescine, cadaverine, histamine, ethylamine, propylamine, ethanolamine, tyramine, tryptamine, spermine, spermidine, phenylethylamine. Detection limits ranged between 0.05 and 0.06 mg of biogenic amine/kg of egg yolk. Two experiments using, respectively, farm and avian eggs were conducted to evaluate yolk biogenic amine concentrations of fresh and stored eggs, and to explain the effect of temperature and time of storage in the levels of biogenic amines during egg shelf-life. Only five of the 11 biogenic amines under study were detected: putrescine, cadaverine, propylamine, ethylamine and ethanolamine. Storage time during shelf-life presented a significant effect on the levels of the five amines (p < 0.01). On the contrary, storage temperature did not presented a significant effect on the levels of the mentioned amines, p > 0.01. The significant reduction of biogenic amine concentration during the shelf-life justified the application of a multiple linear regression using stepwise method to estimate the storage time. The regression equation was applied with success to confirm the storage time of farm eggs and avian eggs that were stored at two different temperatures.     

鲜壳蛋蛋壳灭菌处理与鲜壳蛋保鲜效果对比研究

采用过氧乙酸熏蒸、过氧乙酸浸泡、甲醛熏蒸、高锰酸钾浸泡及开水浸烫等消毒方法处理鲜壳蛋蛋壳表面,通过增菌培养、细菌计数发现,各处理组的消毒效果十分明显,尤其是开水浸烫法,能完全杀灭蛋壳表面的细菌,其它消毒方法中,熏蒸法效果较明显,浸泡法效果稍差,并将处理后的鸡蛋在温度25℃,相对湿度60%-80%贮存20d,通过检测各处理组鸡蛋品质指标的变化,发现开水浸烫组鸡蛋仍保持较高的品质,其余各组鸡蛋品质较差。本研究的结果表明,常规消毒方法(除开水浸烫)能明显抑制蛋壳表面微生物的生长繁殖,但对抑制鸡蛋品质下降效果不佳。     

Effect of exposure to light on physico-chemical quality attributes of sliced dry-cured Iberian ham under different packaging systems

Dry-cured Iberian ham slices were stored under vacuum and under two different atmospheres (N₂ = 70% N₂ + 30% CO₂; Ar = 70% Ar + 30% CO₂) and exposed to lightness or darkness. Physico-chemical, sensory and microbial analysis was carried out throughout 60 days storage. Vacuum samples showed the highest a*-value compared to N₂ and Ar after 30 (P < 0.05) and 60 days (P < 0.05). The influence of illumination during storage was evident after 60 days of storage, L* and a*-values being lower (P < 0.01) in hams exposed to light than those kept in darkness, which can be ascribed to the lower nitrosylmioglobin content in samples exposed to light after 60 days (P = 0.001). Ham slices stored in darkness showed the lowest TBARS values (P < 0.05) and hexanal content (P < 0.05) after 60 days. Slices of ham packed in vacuum showed lower TBARS values than N₂ and Ar batches (P = 0.001), these samples being perceived as more rancid (P < 0.05). The rest of the sensory attributes were not generally affected by gas mixture or illumination (P > 0.05).     

Quality of shell eggs pasteurized with heat or heat-ozone combination during extended storage

The physical quality and functionality of shell eggs, pasteurized with heat or a combination of heat and ozone, were assessed during eight weeks of storage at 4 or 25 °C. Shell eggs were treated as follows: (1) immersion heating that mimics commercial pasteurization processes (egg internal temperature of 56 ± 0.1 °C for 32 min), or (2) a newly developed combination process comprised of heating (56 ± 0.1 °C, internal, for 10 min) followed by gaseous ozone treatment. Eggs were tested for yolk index, Haugh units, albumen pH, albumen turbidity, and percent overrun. Additionally, albumen samples were assayed for lysozyme activity and free sulfhydryl group content, and were analyzed using differential scanning calorimetry and Fourier transform infrared (FTIR) spectroscopy. Both processed and unprocessed eggs maintained superior quality when stored at 4 °C, as opposed to 25 °C. Pasteurization, regardless of method, led to superior maintenance of Haugh units during storage but also increased albumen opacity and decreased albumen overrun. Detrimental effects on quality markers were more severe in heat-pasteurized eggs than those treated with the ozone-based process. Pasteurization of shell eggs by either process did not affect lysozyme activity or sulfhydryl group content. Changes in protein secondary structure, as indicated by FTIR analysis, suggest that the ozone-based process is less damaging to albumen proteins than is the heat-alone process. In conclusion, heat-ozone pasteurization, by virtue of its less severe heat treatment, yields a safe final product that more closely resembles untreated shell eggs.     

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。     

Combined effect of freeze chilling and MAP on quality parameters of raw chicken fillets

The effect of short-term frozen storage prior to thawing on the quality of freeze-chilled chicken fillets was investigated, as was the effect of modified atmosphere packaging (MAP). Four process treatments were used: (1) fresh chicken chilled at 4 degrees C without previous freezing, (2) freeze-chilled for 7 days and thawed at 4 degrees C, (3) chilled at 4 degrees C packaged under MAP (70% N(2)-30%CO(2)), and (4) packaged under MAP, freeze-chilled for 7 days and thawed at 4 degrees C. Microbiological, chemical and sensory analyses were conducted on samples for a period up to 15 days. Freeze-chilled fillets gave a lower total viable count (TVC) at a given sampling day than chilled fillets. MAP, as expected, delayed microbial growth. The Pseudomonads were the dominant microbial species in fillets under aerobic conditions. MAP reduced the populations of Pseudomonads by 2-4 log cfu/g. Lactic acid bacteria (LAB) and Enterobacteriaceae increased progressively for all treatments throughout storage. Yeasts and molds were inhibited by MAP and by freeze chilling. Total volatile basic nitrogen (TVB-N) values increased rapidly for the chilled fillets but remained significantly lower for the freeze-chilled and the MA-packaged samples. MAP and especially freeze chilling enhanced drip loss. MAP did not affect redness or yellowness of product while freeze chilling decreased product redness. Lightness was not affected by either MAP or freeze chilling. Based on taste, which proved to be the most sensitive sensory attribute, shelf life of product ranged from 6 to 7 days for all treatments leading to the conclusion that freeze chilling is a suitable technology for fresh chicken fillets enabling their distribution as a frozen product and upon subsequent thawing at their final destination, their retail display as chilled products. MAP in combination with freeze chilling had a negligible effect on product quality.     

Effect of modified atmosphere packaging on quality factors and shelf-life of surface mould ripened cheese: Part I constant temperature

In the present study, packaging of a surface mould ripened cheese under 2 atm: MAP-A (0% O₂, 27 ± 6% CO₂) and MAP-B (2 ± 1% O₂, 19 ± 2% CO₂) was studied at 12 °C and the results were compared with the existing commercial packaging system (wrapped with waxed paper and inserted in cardboard box). Quality parameters such as colour, texture, pH and moisture content were evaluated after 0, 7 and 14 days of storage, together with a sensory evaluation. Tuckey test and principal components analysis showed that after 14 days of storage, the best conditions for the preservation of the cheeses corresponded to MAP-B. The predicted shelf-life was found to be 14, 6 and 17 days for control, MAP-A and MAP-B respectively. It was concluded that modified atmosphere packaging of surface mould ripened cheese with low levels of O₂ (1-3%) and relatively high levels of CO₂ (17-21%) can be used to extend the shelf-life of soft cheese; however the package has to be suitably designed, as total loss of O₂ (as in MAP-A) would shorten the shelf-life.     

MAP结合低温贮藏对高成熟度鲜枣的保鲜效果

研究了以不同体积分数混合的O2、CO2、N2进行气调包装,在(0±0.5)℃贮藏条件下对着色面积在75%以上的全熟鲜枣(Ziziphus zizyphus)品质的影响。结果表明,经过60d的贮藏,不同体积分数的气调包装均能有效抑制全熟鲜枣果实衰老和营养物质损失,能不同程度地延缓果实中MDA(丙二醛)含量的上升和硬度的下降;降低质量损失和乙醇积累量;减缓鲜枣果实中TA(可滴定酸)含量的下降和颜色变化以及还原糖含量的上升;可有效地防止VC、cAMP(环磷酸腺苷)和总黄酮等营养物质的损失;同时能够较长时间保持果实鲜亮的颜色。其中以气体体积分数为5%O2、2%CO2、93%N2的气调包装对全熟鲜枣的保鲜效果最好。      

A comparison of modified atmosphere and vacuum skin packing for the storage of red meats

The performances of two commercially available packaging systems for prolonging the shelf-life of fresh meat were compared at 1°C and during simulated retail display. Beef and pork loin steaks in modified atmosphere packs (MAP), containing 75% O2 and 25% CO2, developed an initial bright red (beef) or pink (pork) colour, which gradually changed to brownish-red or -pink after 12 days; similar samples in vacuum skin packs (VSP) remained purple-red throughout the storage period. Off-odours developed more rapidly in MAP (8–12 days), possibly due to more extensive growth of Brochothrix thermosphacta and the effects of aerobic conditions on the metabolites of lactic acid bacteria, which predominated in both types of packs. Evidence of rancidity, using thiobarbituric acid assay, was demonstrated in MAP beef after approximately 8 days, but not in VSP. Drip losses in MAP increased after 6 days' storage, but remained generally low in VSP. Physical texture (shear force values of cooked samples) of beef was unaffected by packaging method, but pork in VSP was significantly more tender ( P < 0.001) than in MAP.     

Effect of temperature on the cell wall composition of raisins during storage under a modified atmosphere

 Raisins obtained from seedless grapes ("Flame" variety) were kept under a modified atmosphere (MA) composed of CO₂ (60%) and N₂ (40%), and stored at 10  °C (10MA), 20  °C (20MA), 30  °C (30MA) and 40  °C (40MA). An additional sample was stored under air at 20  °C (20A). Colour, and changes in cell wall components were monitored during storage. At the end of the storage period, the 40MA and 20A samples showed a significant decrease (∼18–19%) in the yield of cell wall material (CWM), whereas less than 6% of CWM had been degraded in the 10MA sample. The decrease in CWM was mainly due to pectic polysaccharide degradation, although for 20A and 40MA samples, hemicelluloses were also affected. Throughout storage, 10MA, 20MA and 30MA samples exhibited similar CWM solubility; however, that of the 40MA sample underwent a significant decrease, from 10% to 4.5%, probably due to the formation of new pectic chains of higher molecular weight. In contrast, the CWM solubility of sample 20A increased from 10% to 15%, suggesting that MA may have promoted the inhibition of pectic-polysaccharide-degrading enzymes. In general, the combined use of relatively low temperatures and a MA helped to preserve both the colour of raisins and maintain the levels of their CWMs at values similar to initial concentrations. Received: 5 October 1998     

Combined effect of MAP and thyme essential oil on the microbiological,chemical and sensory attributes of organically aquacultured sea bass (Dicentrarchus labrax) fillets

The present study evaluated the combined effect of Modified Atmosphere Packaging (MAP) using two different gas mixtures (40% CO₂/50% N₂/10% O₂; treatment M1, 60% CO₂/30% N₂/10% O₂, treatment M2), and thyme oil (0.2% v/w, T) used as a natural preservative, on the quality and shelf life extension of fresh filleted sea bass, product of organic aquaculture, during refrigerated storage (4± 0.5 °C), for a period of 21 days. Aerobically packaged sea bass fillets (A) were used as control samples. The dominant bacteria in the microflora of sea bass fillets, irrespective of treatment, were the pseudomonads and the H₂S-producing bacteria while lactic acid bacteria were also part of the dominant microflora. Total viable counts for fresh sea bass fillets stored aerobically exceeded 7 log CFU/g after 7 days, while treatments A+T, M1, M2 and M2+T reached the same value on days 9, 10, 12 and 19, respectively. Among the chemical indices determined, TBA values were within the good quality limits (2–4 mg MDA/kg), during the sensory shelf lives of sea bass samples, irrespective of treatment. TVB-N proved to be a suitable index for the spoilage of sea bass fillets stored at 4 °C. Samples A and A+T, M1, M2, M2+T exceeded the proposed upper TVB-N acceptability limit (10 mg N/100 g) on days 6, 8, 9, 13 and 17 of storage respectively. TMA-N values of the samples A, A+T and M1, M2, M2+T exceeded the proposed limit (4 mg N/100 g) on days 6, 9, 9–10, 13 and 19 of storage, respectively, and correlated well with the microbiological data, indicating that along with TVB-N, TMA-N may serve as a useful index for sea bass fillets spoilage. As regards sensory evaluation, the presence of thyme oil proved to improve the sensory quality of sea bass fillets when used in combination with MAP2, providing a shelf life of 17 days as compared to 6 days of the control samples.     

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.     

Effect of illumination on the display life of fresh pork sausages packaged in modified atmosphere. Influence of the addition of rosemary, ascorbic acid and black pepper

Pork forelegs were used for manufacturing fresh sausages, treated with different natural antioxidants (rosemary, ascorbic acid and black pepper), packaged in 80% O₂ + 20% CO₂ atmosphere and displayed at 2 ± 1 °C under different lightings (darkness, standard fluorescent, low-UV colour-balanced lamp and standard fluorescent plus a UV-filter). Two packs for each treatment were opened every 4 days for subsequent analysis of colour CIE L^∗, a^∗, b^∗, TBARS, microbial psychrotrophic aerobes and sensory discolouration and off-odour. Lighting with standard fluorescent was highly deleterious for sausage display life, which fell from 12 to 8 days due mainly to early discolouration. Inserting a UV-filter extended display life to 12 days, while the use of a low-UV lamp was not effective in protecting from discolouration. Addition of rosemary plus ascorbic acid, in the absence of black pepper, retarded discolouration only in sausages illuminated with the UV-filter, reaching a display life of 16 days, equal to that of sausages maintained in the dark.     

Effects of calf diet, antioxidants, packaging type and storage time on beef steak storage

The effect of basal dietary supplemented with vegetable oils plus vitamin E (sunflower, soybean, linseed and a basal diet control), type of packaging (MAP or vacuum), addition of natural antioxidant (grape seed, rosemary) and storage time (0, 7, 14 and 21 days) on lipid oxidation, color stability, vitamin E content, and total aerobic bacterial counts in steaks of Longissimus thoracis was studied. The triple interaction diet × time × packaging affected oxidative stability, redness and yellowness of the meat. TBARS values did not increase with time in vacuum-packaged samples for all dietary treatments. However, samples from MAP and control showed the highest TBARS values after 21 days of storage (0.72 mg MDA/kg of meat, P < 0.05). Both exogenous antioxidant extracts and MAP maintained low total aerobic counts in steaks until the 21st day. Calves should be fed a diet supplemented with L-VE, stored in MAP and treated with grape seed extract to extend the shelf life of their meat.     

Effect of modified atmosphere packaging on visual quality and glucosinolates of broccoli florets

Broccoli (Brassica oleracea var. italica) florets were packaged in polyethylene bags with no holes (M₀), two microholes (M₁), and four macroholes (M₂), and then stored at 4 or 20 °C. The effects of modified atmosphere packaging (MAP) treatments on visual quality and glucosinolate contents were determined by comparing with non-wrapped florets. The results showed that MAP treatments, especially with M₀ and M₁, extended the shelf life and reduced the postharvest deterioration of broccoli florets stored at 4 and 20 °C. All three MAP treatments reduced the decreasing concentration rates of individual, total aliphatic and indole glucosinolates in broccoli florets when compared to those in the control, with M₀ being the most significant, followed by M₁ and M₂ during 23 days of storage at 4 °C or 5 days of storage at 20 °C. Broccoli florets with M₀ treatment maintained the visual quality and glucosinolate contents for 13 days at 4 °C and 3 days at 20 °C.     

高体积分数CO2气调包装对冷藏凡纳滨对虾品质的影响

为研究高体积分数CO2气调包装对凡纳滨对虾品质的影响,以空气包装为对照,分别采用100% CO2、80% CO2＋20% N2和50% CO2＋10% O2＋40% N2气调包装对虾,并在（4±1）℃条件下贮藏10 d,期间每2 d测定对虾细菌总数及其挥发性盐基氮值、肌肉纤维长度、硬度、多酚氧化酶活性、白度、感官评分的变化。结果表明：在冷藏条件下,高体积分数CO2气调包装能有效抑制细菌的生长繁殖和多酚氧化酶的活性,且CO2体积分数越高抑制效果越明显;但100% CO2处理的对虾与80% CO2组相比,其样品挥发性盐基氮值较高,肌肉纤维长度和硬度均较小,感官品质较差;50% CO2组对虾白度较低,与空白对照组差异不明显。因此,所选取高体积分数CO2气调包装中,80% CO2组的保鲜效果最佳,能有效延长凡纳滨对虾的冷藏货架期至8 d。