包装、臭氧和保鲜剂处理对‘大红袍’鲜花椒呼吸强度与贮藏效果的影响

为筛选延长鲜花椒贮藏寿命的适宜包装以及臭氧与保鲜剂的适宜浓度,以‘大红袍’鲜花椒为材料,采用聚乙烯PE20(厚20 μm)、PE30(30 μm)和PE50(50 μm)包装袋以及臭氧(O₃,5、15、30 mg/L)、二氧化氯(ClO₂,15、40、80 mg/kg)和双乙酸钠(C₄H₇NaO₄,100、200、400 mg/kg)处理后于(0±0.5) ℃贮藏,测定其冷藏期间的感官品质、褐变率和呼吸强度的变化。结果表明:PE20包装对抑制鲜花椒的褐变和保持感官品质具有较好效果;15 mg/L O₃、40 mg/kg ClO₂和100 mg/kg C₄H₇NaO₄的处理效果较好,尤以40 mg/kg ClO₂处理可显著抑制鲜花椒的呼吸强度和褐变率,保鲜效果最佳,冷藏42 d时褐变率为42%。综上,聚乙烯PE20包装袋及40 mg/kg ClO₂对鲜花椒的保鲜效果最好。     

Poststorage Behavior of Apple Fruit After Low Oxygen Storage as Influenced by Temperatures During Storage and in Transit

‘Delicious’, ‘Newtown’ and ‘Granny Smith’ apples (Malus domestica Borkh.) maintained acceptable flesh firmness and high levels of titratable acids and soluble solids after 9 months of storage in 1% 0₂ at either 0°C or 3.3°C. Low-0₂-stored ‘Delicious’ were kept at 0°C for 6 wk without developing physiological disorders before or after 8 days of ripening at 20°C. Storage at 3.3°C caused ‘Delicious’ to soften faster during 6 wk of post-storage holding plus 8 days of ripening. ‘Newtown’ apples developed flesh browning and alcohol flavor after 9 months of low 0₂ storage at 0°C. ‘Newtown’ fruit stored at 3.3°C developed only minimal incidence of flesh browning and alcohol flavor. ‘Granny Smith’ fruit were free from scald, core flush, flesh browning and alcohol flavor after low 0₂ storage, regardless of storage temperature. However, core flush and flesh browning appeared when ‘Granny Smith’ were kept for 6 wk at 0°C plus 8 days at 20°C.     

CHANGES IN 'DELICIOUS' APPLE BROWNING AND SOFTENING DURING CONTROLLED ATMOSPHERE STORAGE

High CO₂ conditions offered no advantage over normal CA storage in terms of reduced ‘Delicious’ apple browning or softening during a 28 week storage period. After approximately 7–14 weeks in CA storage, ‘Delicious’ apples showed significant losses in PPO activity, browning tendency and firmness. Electrolyte leakage reached a maximum at 11.5 weeks and declined, while total phenolics remained fairly constant. The changes observed may indicate a loss in membrane integrity and decompartmentalization after 7–14 weeks of storage, which may in turn allow for increased enzymatic browning. Polygalacturonase activity was only detectable at harvest. Holding apples for additional time in air following removal from CA storage appears to accelerate changes in these characteristics.     

不同厚度PE袋对冷链物流过程中荔枝褐变的影响

本研究采用厚度为10、20、30 μm的聚乙烯袋包装‘鸡嘴荔’荔枝,结合冰袋模拟物流包装,研究在当前冷链物流体系不完善情况下对荔枝果皮褐变、细胞膜透性、花青素代谢的影响。结果表明:在贮藏过程中通过对果皮褐变、适销果比率及果实色差分量变化分析发现20 μm聚乙烯袋包装效果较好,其次是10 μm厚度,最差是30 μm。并且20 μm厚度聚乙烯袋显著抑制细胞膜透性上升,这体现为贮藏期间果实组织更低的相对电导率（P<0.05）。进一步研究结果表明:聚乙烯袋（20 μm）能通过抑制花青素生物合成中的关键酶苯丙氨酸解氨酶活性延缓花青素分解,并结合抑制多酚氧化酶和过氧化物酶活性延缓荔枝果皮褐变。综上,20 μm聚乙烯袋相对于其它厚度可明显抑制荔枝褐变,有效保持果实品质,延长货架期。     

Modified-atmosphere packaging of minimally processed “Lollo Rosso” (Lactuca sativa) Phenolic metabolites and quality changes

 The effect of modified-atmosphere packaging (MAP) on the amount of soluble phenolics in, and the visual appearance of, white, green and red tissues of minimally processed “Lollo Rosso” lettuce were evaluated. Minimal processing induced a two-fold increase in the amount of soluble phenylpropanoids in the midribs during storage in air at 5°C. When the lettuce was stored in the presence of 2–3% O₂ and 12–14% CO₂, this increase was not induced and no browning was observed. A particularly marked decrease in the amount of phenylpropanoids was observed in MAP-stored green and red tissues. The concentrations of flavonoids and anthocyanins did not change much in midribs and green tissues, while they were significantly degraded in red tissues under MAP conditions. MAP storage proved useful in the prevention of browning, the main cause of quality loss in minimally processed “Lollo Rosso” lettuce. However, MAP storage was not so beneficial for the preservation of the quality of red tissues and, in fact, their overall visual quality, texture, aroma and macroscopic breakdown under MAP conditions were worse than those of air-stored tissues. Received: 5 November 1997     

Modified-atmosphere packaging of minimally processed “Lollo Rosso” (Lactuca sativa) Phenolic metabolites and quality changes

 The effect of modified-atmosphere packaging (MAP) on the amount of soluble phenolics in, and the visual appearance of, white, green and red tissues of minimally processed “Lollo Rosso” lettuce were evaluated. Minimal processing induced a two-fold increase in the amount of soluble phenylpropanoids in the midribs during storage in air at 5°C. When the lettuce was stored in the presence of 2–3% O₂ and 12–14% CO₂, this increase was not induced and no browning was observed. A particularly marked decrease in the amount of phenylpropanoids was observed in MAP-stored green and red tissues. The concentrations of flavonoids and anthocyanins did not change much in midribs and green tissues, while they were significantly degraded in red tissues under MAP conditions. MAP storage proved useful in the prevention of browning, the main cause of quality loss in minimally processed “Lollo Rosso” lettuce. However, MAP storage was not so beneficial for the preservation of the quality of red tissues and, in fact, their overall visual quality, texture, aroma and macroscopic breakdown under MAP conditions were worse than those of air-stored tissues. Received: 5 November 1997     

Chemical and microbial stability of high moisture dried apricots during storage

BACKGROUND: This study was conducted to determine the chemical and microbial stability of high moisture (HM) dried apricots during storage at 5, 20 and 30 °C for a period of 8 months. HM dried apricots were obtained by rehydrating dried apricots in ‘water’ and ‘water + H₂O₂’. RESULTS: Analysis of kinetic data suggested first‐order models for loss of SO₂ and non‐enzymatic browning reactions. Higher storage temperatures increased the rate of SO₂ loss and formation of brown colour in HM dried apricots. Results from extensive colour measurements (non‐enzymatic browning, reflectance colour and β‐carotene) revealed that the colour of HM dried apricots stored at 5 °C was almost unchanged during 8 months of storage. The colour of samples stored at 30 °C was unacceptable starting from 2 months of storage. Total mesophilic aerobic bacteria counts decreased 0.7, 1.1 and 1.5 log cycles after 8 months of storage at 5, 20 and 30 °C, respectively. For the same storage period, the decrease in mesophilic bacteria was 0.62 log cycle in samples rehydrated in ‘water + H₂O₂’ and stored at 20 °C. CONCLUSION: These results suggest that HM dried apricots should be stored at temperatures lower than 20 °C to preserve the characteristic golden yellow colour. A relatively low level of SO₂ (1458 mg kg^?1 at 200 g kg^?1 moisture level) was sufficient to prevent the growth of spoilage organisms in HM dried apricots at all three storage temperatures. Copyright © 2008 Society of Chemical Industry     

Modified atmosphere influences aflatoxin B1 contamination and quality of peanut (Arachis hypogaea L.) kernels cv. Khon Kaen 84-8

Storage of ‘Khon Kaen 84-8’ peanut kernels in laminated bags (Low density polyethylene (LDPE)/Nylon) (20×30 cm; 120 μm thickness) under different packaging atmospheres had effect on quality, fungal occurrence and aflatoxin B₁ (AFB₁) contamination. During fifteen week storage, peanuts (6.4% moisture content) were kept under different packaging atmospheres with some inoculated (Inoc.) and without (Non-Inoc.) aflatoxin producing fungus Aspergillus flavus. The treatments include; 100% CO₂+Inoc., 100% N₂+Inoc., vacuum + Inoc., Air + Inoc., and Air + Non-Inoc. packed with only ambient air. The storage room conditions were a temperature of 29±2 °C and 70 ± 5% r. h. Mycobiota occurrence, AFB₁ level, moisture content, lipase activity, free fatty acids and rancidity (Thiobarbituric acid; TBA value) were investigated. A total of five major fungi were identified with four storage fungi and one field fungus; Rhizopus stolonifer, Aspergillus niger, A. flavus, Penicillium spp., and Fusarium spp., respectively. Packaging in 100% CO₂+Inoc. significantly repressed the fungal occurrence especially A. niger while all other packaging atmospheres suppressed proliferation of both R. stolonifer and Penicillium spp. The peanuts kept in vacuum + Inoc. package revealed AFB₁ level below detection limit (0.4 μg/kg). Peanut kernels in 100% CO₂+Inoc. packaging atmosphere maintained an acceptable color indicated by L* and a* values, as well as the color change (ΔE) compared to other treatments. Different packaging atmospheres showed variable results in relation to the free fatty acids level with packaging under 100% N₂ revealing the lowest. Subsequently, 100% N₂ packaging atmosphere relatively inhibited rancidity occurrence in peanut kernels during storage. The results of this study portray that 100% CO₂, 100% N₂ and vacuum packaging atmosphere could have a potential to suppress occurrence of mycobiota, maintain peanut kernel quality in relation to color and lipid oxidation, and as well curtail AFB₁ contamination respectively, for fifteen weeks or more given the quality of kernels at the end of storage.     

Effect of packaging treatments and vacuum-cooling on quality of winter harvested iceberg lettuce

Heads of winter harvested iceberg lettuce (Lactuca sativa L. cv. Coolguard) individually packed or sealed in perforated (22 μm thickness) or unperforated (25, 30 or 40 μm thickness) polypropylene films were stored up to 2 weeks at 2°C (storage period) and then held for 2.5 days at 12°C (shelf-life period). Five packaging treatments together with passive or active modification of the atmosphere within the package were applied. Vacuum-cooling was superimposed on these five treatments. Weight loss, wilting, physiological disorders, bacterial decay and quality were monitored. In all treatments, both slight severity of pink rib and russet spotting occurred. Brown stain and heart leaf injury were only detected on heads in unperforated bags. Low oxygen was generally related to a high quality score. Passive MAP in 40 μm PP and active (initial 5% O₂ and 0% CO₂) MAP in 30 μm PP were the best treatments for overall visual quality. Vacuum-cooling reduced both pink rib and heart-leaf injury but the effect only showed up during shelf-life period.     

采后1-MCP和MAP处理对‘红富士’苹果冷藏和货架期品质的影响

对‘红富士’苹果进行1.0 μL/L 1-甲基环丙烯（1-methylcyclopropene,1-MCP）和自发气调包装（modified atmosphere package,MAP）处理,继而进行0 ℃冷藏和20 ℃货架贮藏。结果表明：贮藏期间,‘红富士’苹果果实硬度和可滴定酸含量下降,可溶性固形物含量升高,虎皮病和果心褐变增多。1-MCP处理能较好维持冷藏期间‘红富士’苹果果实硬度和可溶性固形物含量,降低了包装内CO2和乙烯含量。同时,1-MCP明显降低了冷藏期间虎皮病发病指数、果心褐变指数以及果柄端果肉褐变率,显著抑制果皮α-法尼烯及共轭三烯的生成。1-MCP＋MAP结合使用可较好维持果实可滴定酸含量和果皮色泽、抑制果柄端果肉褐变。综合分析认为,1-MCP＋MAP处理能较好维持‘红富士’果实冷藏和货架期间的品质,并显著抑制果实虎皮病的发生。     

Effect of the packaging method and the storage time on lipid oxidation and colour stability on dry fermented sausage salchichón manufactured with raw material with a high level of mono and polyunsaturated fatty acids

The effects of fatty acid composition, two packaging methods (vacuum and 20% CO₂/80% N₂) and storage under refrigeration for 210 days were evaluated on a dry fermented sausage (salchichón), manufactured with raw material enriched in monounsaturated or polyunsaturated fatty acids. Fatty acid composition was determined on sausage mixtures and on ripened sausages and lipid oxidation and colour stability was determined on ripened sausage at different times during storage. The modification of fatty acid composition of the sausages raised the nutritional quality, slightly affecting the colour properties. Dry fermented sausages enriched in polyunsaturated and monounsaturated fatty acids presented higher lipid oxidation values than the control ones. Both packaging methods (vacuum and 20% CO₂/80% N₂) during 210 days of chilled storage had minor effects on the colour and the lipid oxidation stability.     

High carbon-di-oxide modified atmospheric packaging on quality of ready-to-eat minimally processed fresh-cut iceberg lettuce

Fresh-cut lettuce is a very well-known salad for today''s routines because it obliges minimal preparation to minimize the loss of health beneficial vitamins, minerals, antioxidants and other phytochemicals. It is a prodigious challenge to serve its consumers fresh. Quality of freshly processed lettuce under high CO₂ modified atmosphere packaging (MAP) has been investigated as a realistic alternative technique for its preservation. Storage under high CO₂ atmospheric treatments exhibited a significant impact in microbial development, electrolyte leakage, volatile metabolites and sensory quality of fresh-cut iceberg lettuce. This storage condition (MAP 1: 5 kPa O₂ and 20 kPa CO₂ balanced by N₂ at 7 °C for 6 days) inhibited the growth of mesophilic bacteria and yeasts; delayed the enzymatic browning (cut-edges and intact surface) of fresh-cut iceberg lettuce and overall visual quality was also in acceptance limit. The development of off-odors was perceived in high CO₂ MAP as a consequence of volatiles (ethanol and acetaldehyde) accumulation which was persisted at an inexcusable level during 6 days of storage periods.     

过氧化氢处理对采后‘黄冠’梨果皮褐变及果实品质的影响

‘黄冠’梨低温贮藏过程中果皮褐变严重,为解决果皮褐变问题,开发控制果皮褐变的新技术,本研究分别采用3、20 mmol/L的过氧化氢(H2O2)水溶液浸泡处理‘黄冠’梨,探讨H2O2预处理对梨果皮细胞抗氧化防护体系、低温贮藏期间果皮褐变、果实品质的影响。结果表明,与对照组(未经H2O2处理)相比,20 mmol/L的H2O2显著降低了‘黄冠’梨果皮褐变率及褐变指数,抑制了多酚氧化酶(polyphenol oxidase,PPO)的活性和果皮酚类物质尤其是单体绿原酸、儿茶素和熊果苷的消耗,不同程度地提高了过氧化物酶、超氧化物歧化酶、过氧化氢酶、抗坏血酸过氧化物酶活力以及果皮自由基清除能力,降低了丙二醛积累,有效地增强了果皮抗氧化防护能力,并且能够使果实在低温贮藏后的货架期间保持较高的硬度、可滴定酸含量、糖酸比及总可溶性固形物含量,食用感官综合品质在低温贮藏和货架期间均优于对照组。研究表明,采后‘黄冠’梨经H2O2预处理,可以诱导性地增强果皮抗氧化酶活性,抑制PPO酶活性和酚类物质消耗而减少低温贮藏过程中果皮褐变的发生。     

Control of internal browning and quality improvement of ‘Fuji’ apples by stepwise increase of CO2 level during controlled atmosphere storage

To control internal browning injury and to reduce quality loss in ‘Fuji’ apples during storage, a stepwise controlled atmosphere (CA) method was applied in this study. Both non‐bagged and bagged apples during maturation were stored at 0 °C under 1% O₂ + 1% CO₂, 1% O₂ + 3% CO₂ or air for 10 months, and 1% O₂ + 1% CO₂ for 2 months followed by 1% O₂ + 3% CO₂ for 8 months (stepwise CA). The concentrations of internal ethylene and carbon dioxide in apples kept for 24 h at 20 °C after storage under CA conditions were maintained at low level, but there was no effect of stepwise CO₂ increase on internal gas concentrations. The non‐bagged and bagged apples stored under stepwise CA were not significantly different from those stored under 1% O₂ + 3% CO₂ continuously for 10 months in term of flesh firmness, titratable acidity and yellowing index. However, the apples stored under stepwise CA were firmer, more acid and greener than those stored under 1% O₂ + 1% CO₂ continuously for 10 months. Internal browning injury occurred in apples stored under 1% O₂ + 3% CO₂ continuously for 10 months, but it was suppressed completely by stepwise CA storage. The stepwise CA, increasing of CO₂ level after holding at 1% CO₂ for the first 2 months of storage, was effective in maintaining the quality and controlling the internal browning injury in non‐bagged and bagged ‘Fuji’ apples. Copyright © 2005 Society of Chemical Industry     

Effects of various coatings and antioxidants on peel browning of ‘Bartlett’ pears

Peel browning of ‘Bartlett’ pears (Pyrus communis L) caused by various mechanical injuries during postharvest handling results in a reduction in visual quality. Various commercial and experimental coatings and antioxidants with potential to reduce peel browning of pears have been evaluated. Treatment with 0.2% diphenylamine (DPA) or 0.3% ethoxyquin (Eth) reduced peel browning on ‘Bartlett’ pears induced by vibration, rolling or scuffing. However, this effect only lasted for about 5 days when treated pears were stored at 0 °C. For the consideration of practical use, pears would have to be treated and packed shortly before transport to achieve a reduction in peel browning. DPA and Eth did not reduce peel browning on pears induced by handling at 20 °C after treatment. It is suggested that tight‐fill packaging and use of DPA or Eth would best reduce peel browning. Copyright © 2004 Society of Chemical Industry     

Browning,polyphenol oxidase activity and headspace gas composition during storage of minimally processed pears using modified atmosphere packaging

Modified atmosphere packaging was used to prevent browning of minimally processed Conference pears, thus extending their shelf‐life. Colour changes as well as PPO activity were strongly influenced by the package headspace gas composition, which was determined by the packaging conditions. The initial colour of minimally processed pears was preserved for several weeks under cold storage in plastic pouches of very low O₂ permeability and an initial atmosphere of 100% N₂. A fractional conversion kinetic model fitted the experimental browning data with high accuracy. Colour degradation (ΔE*) of minimally processed pears occurred exponentially (k_ΔE = 0.019–0.077 day^?1) owing to changes in lightness (k_L = 0.021–0.07 day^?1). In contrast, PPO exhibited a linear increase in activity which could be related to the availability of O₂ in the package headspace. © 2002 Society of Chemical Industry     

Browning Susceptibility and Changes in Composition During Storage of Carambola Slices

Browning and changes in the composition of sliced and whole carambola (Averrhoa carambola L.) fruit during storage were investigated. Susceptibility to browning after slicing, packaging and storage for 4 wk at 4.4°C varied considerably between four cultivars and five selections. There was no difference in browning susceptibility between fruit harvested at mature green or breaker stages of maturity. Freshly sliced carambola browned only slightly when exposed to air, but packaged slices that had been stored for 2 or more wk at 4.4°C browned rapidly (within 6 hr) when exposed to air. Whole fruit stored at 4.4°C for up to 6 wk, then sliced, showed much less susceptibility to browning. Ascorbic acid decreased and polyphenoloxidase activity increased in carambola slices during storage, but less in whole fruit. Treating slices with 1.0 or 2.5% citric acid + 0.25% ascorbic acid (in water) prior to packaging was very effective in limiting browning.     

Postharvest performance of fresh‐cut ‘Big Top’ nectarine as affected by dipping in chemical preservatives and packaging in modified atmosphere

Fresh‐cut ‘Big Top’ nectarines were dipped in 2% (w/v) ascorbic acid–1% (w/v) calcium lactate and stored at 4 °C for up to 12 days in 10 kPa O₂‐ and 10 kPa CO₂‐modified atmosphere packaging (MAP). The used microperforated plastic film allowed O₂ and CO₂ concentrations to reach steady values from the fifth day in storage onwards. Samples stored in MAP after chemical dipping showed the highest visual quality score, slight browning symptoms, increment in firmness and very low ethanol and acetaldehyde content. The chemical dipping also increased antioxidant capacity, probably due to the effect of ascorbic acid. The results suggested that the control of yeasts was mainly exerted by MAP, whereas only a slight effect was achieved by the chemical dipping. Therefore, MAP plus ascorbic acid/calcium lactate dipping was the best combination to preserve phytochemical content, antioxidant capacity and microbiological safety of fresh‐cut nectarines during storage.     

STORAGE OF MINIMALLY PROCESSED ROMAINE LETTUCE UNDER CONTROLLED ATMOSPHERE

The effects of CO₂ and O₂ concentration on the preservation of minimally processed Romaine lettuce (Lactuca sativa, L.) under controlled atmosphere were studied. The lettuce was stored at 4C for 16 days under a continuous stream of nitrogen containing 0.5 to 2% O₂ and 2 to 15% CO₂. Increasing the CO₂ content in the atmosphere to 10% or more reduced enzymatic browning due to wounding and improved lettuce visual quality. However, 15% CO₂ caused brown lesions (brown stain, BS) after 8 days of storage. Decreasing the O₂ content to 1% in the presence of 10% CO₂ reduced tissue browning slightly without lowering the content of phenols, but 0.5% O₂ increased browning and anaerobiosis. Among the atmospheres tested, 10% CO₂ and 1% O₂ were beneficial for maintenance of the quality of minimally processed Romaine lettuce.     

茉莉酸甲酯处理对采后龙眼果皮褐变的影响

本实验以10、50、100μmol/L MeJA处理‘储良’龙眼(Dimocarpus longan Lour.)果实,研究其对(20±1)℃、85%相对湿度贮藏条件下的龙眼果皮褐变的影响。结果表明：与对照组相比,MeJA处理可有效降低‘储良’龙眼采后果皮褐变指数、果皮细胞膜透性和果肉自溶指数,而且MeJA浓度越高,抑制效果越明显。与对照组相比,100μmol/L MeJA处理龙眼果实能够保持较高的果皮总酚和类黄酮含量,降低果皮多酚氧化酶活力,有效提高果皮过氧化物酶和苯丙氨酸解氨酶活力;另一方面,MeJA处理可以有效降低超氧阴离子自由基产生速率以及H₂O₂含量,有效增强抗氧化酶(超氧化物歧化酶、过氧化氢酶)活力以及1,1-二苯基-2-三硝基苯肼自由基清除能力,提高果皮抗氧化能力。综上,100μmol/L MeJA处理可抑制龙眼果实采后部分酚类物质代谢,增强其抗氧化能力,从而延缓龙眼采后果皮褐变的发生,延长贮藏保鲜期。