Response of kiwifruit (Actinidia deliciosa cv. Allison) to post-harvest treatment with 1-methylcyclopropene

Summary

Experiments were conducted to observe the effect of different concentrations of 1-methylcyclopropene (1-MCP) on the post-harvest life and quality of ‘Allison’ kiwifruit (Actinidia deliciosa). Fruit were treated with 1-MCP at 0.5 µl l^–1, 1.0 µl l^–1, or 2.0 µl l^–1, un-treated fruit served as controls. Each 1-MCP treatment was applied for 24 h at 20°C. After treatment, fruit were transferred to ambient temperature storage (22º ± 4ºC; 65 – 70% relative humidity) for 18 d, during which time observations on various physical, physiological, and biochemical parameters were recorded at 3 d intervals. Our results indicated that 2.0 µl l^–1 1-MCP was the most effective treatment to delay softening and ripening in ‘Allison’ kiwifruit, as such fruit showed the lowest mean weight loss (9.8 ± 0.2%), the highest mean fruit firmness value (32.7 ± 0.2 N), and began to ripen only after 12 d in storage, whereas untreated fruit started ripening on day-6 of storage. The activities of fruit softening enzymes such as polygalacturonase (PG; 58.5 ± 0.3 µg galacturonic acid g^–1 FW h^–1), and lipoxygenase (LOX; 3.96 ± 1.3 µmoles linoleic acid oxidised min^–1 g^–1 FW h^–1) were lower, and total phenolics (TP) contents (24.3 ± 0.3 mg 100 g^–1) and anti-oxidant (AOX) activities (12.5 ± 0.03 µmol Trolox g^–1 FW h^–1) were higher in 1-MCP-treated fruit than in untreated fruit (PG, 98.3 ± 0.5 µg galacturonic acid g^–1 FW h^–1; LOX, 4.39 ± 1.0 µmoles min^–1 g^–1 FW h^–1; TP, 5.3 ± 0.6 mg 100 g^–1; AOX, 4.7 ± 0.02 µmol Trolox g^–1 FW h^–1, respectively). In addition, 1-MCP-treated fruit exhibited lower rates of respiration (48.3 ± 0.4 ml CO₂ kg^–1 h^–1) and ethylene production (30.2 ± 0.02 µl kg^–1 FW h^–1) than untreated fruit (58.9 ± 0.6 ml CO₂ kg^–1 h^–1; 38.7 ± 0.04 µl kg^–1 FW h^–1, respectively). Similarly, 1-MCP-treated fruit had higher titratable acidity (TA; 1.33 ± 0.3%) and ascorbic acid (AA) contents (115.9 ± 2.6 mg 100 g^–1 pulp) and lower soluble solids contents (SSC; 8.33º ± 0.2º Brix) than untreated kiwifruit (TA, 1.0 ± 0.2 %; AA, 105.3 ± 2.2 mg 100 g^–1 pulp; SSC, 13.7º ± 0.3º Brix, respectively). Thus, 2.0 µl l^–1 1-MCP can be used for the post-harvest treatment of ‘Allison’ kiwifruit to enhance its shelf-life and marketability by approx. 6 d.     

1-MCP对苹果采后生理的影响

以金冠、乔纳金、红富士和津轻苹果果实为试材,在常温(20±1℃)条件下,研究了不同浓度的1-MCP(1-甲基环丙烯)对果实呼吸强度、硬度、可滴定酸、叶绿素、淀粉指数和可溶性固形物含量的影响。结果表明,与对照相比,1-MCP可以明显降低果实的呼吸强度,延迟果实呼吸高峰的出现,从而抑制果实的后熟与衰老。1-MCP处理明显地减缓了果实硬度和酸度的下降,减少了叶绿素降解和淀粉的分解和转化。在贮藏期间,1-MCP处理增加了乔纳金和红富士果实苦痘病的发生。果实硬度、可滴定酸和果皮叶绿素的变化有极显著的相关性,与果实品质变化密切相关。     

Changes in Ripening Behaviors of 1-MCP-Treated ‘d’Anjou' Pears After Storage

Abstract

1-Methylcyclopropene (1-MCP), an ethylene action inhibitor, was applied to ‘d’Anjou' pears (Pyrus communis L.) at 20°C between 2 and 5 days after harvest. Scald of ‘d’Anjou' pears was completely controlled by 1-MCP at a concentration between 0.05 and 0.3 µl l1 after a prolonged cold storage plus 7 days of exposure to an environment with or without 500 µl l1 ethylene at a temperature of 20°C or 25°C. 1-MCP inhibited the biosyntheses of α-farnesene and its oxidative products (conjugated trienes) and thus controlled scald. However, fruit treated with the above concentrations of 1-MCP did not ripen normally in an environment with or without ethylene. Ethylene production and fruit softening of 1-MCP-treated ‘d’Anjou' pears were inhibited during 7 and 15 days at 20°C. ‘d’Anjou' fruit treated with 0.01 and 0.02 µl l¹ 1-MCP ripened normally on day 7 at 20°C after 3 months of cold storage at ? 1°C, and ripened fruit did not develop any incidence of scald. Untreated fruit developed substantial scald. After 4 months of storage or longer, both untreated fruit and fruit treated with 0.01 and 0.02 µl l 1 1-MCP developed an unacceptable incidence of scald upon ripening. Thus, use of other scald control methods may be necessary in addition to treatment with a low dosage of 1-MCP to insure both normal ripening and scald control for d'Anjou pear fruit from the Mid-Columbia district.     

Re-initiating softening ability of 1-methylcyclopropene-treated ‘Bartlett’ and ‘d’Anjou’ pears after regular air or controlled atmosphere storage

Summary

‘Bartlett’ and ‘d’Anjou’ pears treated with 300 nl l^–1 1-methylcyclopropene (1-MCP) did not soften to eating quality within 7 d, a desirable ripening period. A pre-conditioning method was evaluated as a means to re-initiate the softening ability of pears prior to marketing. Fruit were treated with 1-MCP and stored at –1°C in regular air, or in a controlled atmosphere for 2 – 9 months. After storage, fruit were pre-conditioned with nine temperature (10°, 15° or 20°C) and time (5, 10 or 20 d) combinations. Pre-conditioned fruit were then assessed for ripening ability following storage for 14 d at 20°C. The ripening ability of 1-MCP-treated ‘Bartlett’ fruit recovered in response to many pre-conditioning combinations of 10° – 20°C for 10 – 20 d, as indicated by a decrease in flesh firmness to 27 N or lower. The requirements for pre-conditioning regimes are storage atmosphere- and time-dependent. For ‘d’Anjou’ pears, no pre-conditioning combination resulted in re-initiating the ripening of fruit treated with 300 nl l^–1 1-MCP. However, when the 1-MCP dose was 50 nl l^–1, ‘d’Anjou’ pears ripened over an extended shelf-period with a substantial decrease in superficial scald. The results indicate that treatment with 1-MCP at approx. 50 nl l^–1, combined with a pre-conditioning prior to marketing, is a potential means to control scald in ‘d’Anjou’ fruit. Re-initiation of ripening occurred concomitantly with a substantial increase in ethylene production. The control of superficial scald by 1-MCP in ‘d’Anjou’ pears was due to the inhibition of the biosynthesis of -farnesene and conjugated trienes.     

1-MCP 对新红星苹果乙烯代谢和贮藏品质的影响

 以新红星苹果为试材, 研究了室温贮藏和低温贮藏两种条件下1-MCP (1 - 甲基环丙烯) 对果实乙烯释放量、内源乙烯浓度、硬度、可滴定酸含量及可溶性固形物含量的影响。结果表明, 300 nL·L ^-1浓度的1-MCP 能显著抑制果实乙烯释放, 延缓乙烯高峰的出现, 延缓果实硬度和可滴定酸含量的下降, 但对可溶性固形物含量无影响。     

Effect of temperature on anthocyanin accumulation in apple fruit as affected by cultivar,stage of fruit ripening and bagging

Non-bagged and bagged apples of cvs Jonathan, Fuji, Jonagold and Tsugaru were harvested at different stages of ripening and irradiated with light at 15, 20 and 25°C. The changes in anthocyanin accumulation during ripening varied with temperature, cultivar and bagging or otherwise. In ‘Jonathan’, the optimum temperature for anthocyanin accumulation increased clearly from 15°C to 25°C in non-bagged and from 20°C to 25°C in bagged fruit as it ripened. In ‘Fuji’ and ‘Jonagold’, 20 and 15°C, respectively, were always the optimum for anthocyanin synthesis in non-bagged and bagged apples. In non-bagged and bagged ‘Tsugaru’, the optimum temperaturfe increased from 15°C to 20°C with ripening.     

1-MCP和CO2高透性保鲜袋气调包装对富士苹果贮藏品质的影响

以富士苹果为试材,研究1-MCP和CO2高透性保鲜袋气调包装（MAP）对富士苹果贮藏品质的影响。结果表明：1-MCP和CO2高透性保鲜袋气调包装均能有效抑制富士苹果贮藏过程中呼吸强度的增加,减缓果实硬度、SSC和TA含量的下降,抑制果实失重率的增加。其中,1-MCP结合CO2高透性保鲜袋气调包装处理效果更佳,更好地保持果实的品质。     

Effects of nitric oxide fumigation on post-harvest core browning in ‘Yali’ pear (Pyrus bretschneideri Rehd.) during cold storage

Summary

Core browning often occurs as a physiological disorder in ‘Yali’ pear (Pyrus bretschneideri Rehd.) and results in a high losses during storage. In this study, the effects of fumigation with nitric oxide (NO) gas on the incidence of core browning in ‘Yali’ pears during cold storage were investigated. ‘Yali’ pear fruit were treated with 0, 10, 20, or 30 µl l^–1 NO at 25º ± 2ºC for 3 h under anaerobic conditions, then stored at 0º ± 1ºC under normal air for up to 120 d. The data showed that fumigation with 20 µl l^–1 NO was most effective at suppressing core browning. Thereafter, treatment with 20 µl l^–1 NO was used for comparisons with untreated control fruit in experiments to measure changes in total phenolics contents, polyphenol oxidase (PPO) activities, and the contents of glutathione (GSH), ascorbic acid (AsA), and NO in fruit core tissue during storage. The results showed that NO-fumigated fruit had lower PPO activity, but higher GSH and AsA contents in their core tissue compared with untreated control fruit. NO fumigation also maintained higher endogenous NO levels in core tissue after 60 d in storage, while the total phenolics contents of fruit remained at lower levels until day-100 of storage. These results indicate that the inhibitory effect of fumigation with

20 µl l^–1 NO on core browning was associated with its effects on reducing PPO activity and total phenolics contents, while maintaining the contents of GSH and AsA in core tissue of ‘Yali’ pear during cold storage.     

中晚熟苹果新品种‘苹艳’

 ‘苹艳’苹果是以‘岩富10’ב红津轻’杂交育成的新品种。果实近圆形,大小整齐,平均单果质量172.1 g,果形指数0.84,果实全面着鲜红色,有条纹;果肉浅黄,肉质细,松脆,果汁多,有香气,酸甜适口;采后硬度（去皮）8.5 kg · cm-2,可溶性固形物15.8%,品质佳。具有外观美,风味浓,品质优,早果,丰产,抗病性强,耐瘠薄等特点。     

Involvement of 1-methylcyclopropene in ripening of harvested mei (Prunus mume) fruit

Summary

Harvested mei (Prunus mume) fruit were stored at 20°C after exposure to 500 nl l^–1 1-methylcyclopropene (1-MCP) for 8 h. Firmness, peel colour, chlorophyll content, chlorophyllase activity, soluble solids content (SSC), titratable acidity (TA), respiration and ethylene production, and cell wall hydrolysis enzyme activities were monitored to determine the efficacy of 1-MCP treatment in delaying mei fruit ripening compared to untreated control fruit. Results showed that control ‘daqinghe’ mei fruit displayed typical climacteric patterns of respiration and ethylene production. Peak CO₂ production and ethylene production were observed after 6 d. Fruit softening was accompanied by a progressive decrease in colour parameters expressed as hue angle (h°), chlorophyll content, SSC, TA and increases in chlorophyllase, pectin methylesterase (PME) and polygalacturonase (PG) activities. 1-MCP treatment prior to the climacteric increase significantly delayed the onset of the climacteric peaks of CO₂ and ethylene production. These delays were associated with reductions in fruit softening, consistent with delaying the activities of PME and PG. Fruit treated with 1-MCP exhibited less peel colour change from green-to-yellow because of their lower levels of chlorophyllase activity and less chlorophyll breakdown. Moreover, 1-MCP treatment also significantly retarded reductions in SSC and TA compared with control fruit. The shelf-life of mei fruit ripening was increased by 4 d following 1-MCP treatment. Thus, 1-MCP treatment can markedly extend the post-harvest life of ‘daqinghe’ mei fruit.     

1-MCP及膜袋与温度耦合处理对‘富士'苹果贮藏效果研究

对'富士'苹果进行1-MCP(1-甲基环丙烯)及膜袋与温度耦合处理贮藏保鲜试验,试验设6个处理:室温对照、室温+1-MCP、室温+膜袋、冷藏对照、冷藏+1-MCP、冷藏+膜袋.结果表明:(1)膜袋处理能显著延长'富士'苹果贮期,而1-MCP(1 000 nl/L,下同)不能显著延长'富士'苹果贮期;各处理中,冷藏+膜袋贮期最长,室温+1-MCP贮期最短.(2)室温(18℃)贮藏条件下,1-MCP及膜袋对'富士'苹果贮藏期间的硬度影响差异不显著;冷藏(5℃)条件下,1-McP处理的'富士'苹果贮藏181 d时的硬度显著高于对照及膜袋.(3)室温贮藏22 d时,1-MCP处理的果实可溶性固形物含量(TSS)显著高于膜袋,但和对照差异不显著;冷藏181 d时,1-MCP及膜袋处理果的TSS和对照无显著差异.(4)室温耦合条件下1-MCP处理加速了贮藏期间'富士'苹果的腐烂,使商品果率迅速降低.综合分析认为:无论室温还是冷藏贮果,膜袋处理效果都最好.     

1-MCP verlängert die Lagerfähigkeit und vermindert Schalenbräune bei der Apfelsorte ‘Berlepsch’

‘Berlepsch’ as an apple cultivar of large vitamin C contents in excess of 30?mg vitamin C/100?g FM looses marketing share due to its poor storage quality and sensitivity to superficial scald. The objective of the present work was to use 0, 500 or 1000?ppb of 1-MCP (Smartfresh^TM) for 24 hours at 2?°C to overcome these two cultivar-related shortcomings. Slightly overripe apples were stored at 2?°C, 95% relative humidity either in normal air (NA) or in controlled atmosphere (CA) under 2% CO₂ and 1.8% O₂. Each of these six treatments consisted of four replicates of ca. 20?kg apples each. Treatments with 1-MCP did not affect the fruit sugar content. While the storage conditions (NA or CA) did not affect initial fruit respiration, 1-MCP reduced final fruit respiration to ca. 60% and 1-MCP effects on respiration rates in shelf life were more pronounced than in storage. While 1-MCP reduced the initial ethylene formation from 70 to nearly 0?μl/kg/h, this effect was declined with prolonged storage. Similarly, the temperature driven increase in ethylene evolution during shelf life was not affected by 1-MCP treatments. MCP treated fruit lost less weight in storage and shelf life relative to untreated fruits. Doubling the 1-MCP concentration from 500?ppb to 1,000?ppb did not further reduce respiration, ethylene formation, loss of fresh mass or incidence of superficial scald. This corresponds to the dose of 1-MCP commonly used in fruit storage.     

1-MCP和延迟预冷对‘蜜脆’苹果冷藏效果的影响

以‘蜜脆’苹果为试材,研究1-MCP和延迟预冷处理对其冷藏效果的影响,为‘蜜脆’苹果的贮藏保鲜提供一定的理论依据和技术指导。分别采用1-MCP(1.0μL.L-1,24 h)、延迟预冷(20℃,7 d)及2者的结合对‘蜜脆’苹果进行采后处理,处理后的果实置于(3±0.5)℃下冷藏,定期测定贮藏期的各项生理生化指标,并在贮藏末期观察统计主要生理病害的病情指数。结果表明,1-MCP能显著抑制果实的乙烯释放速率和呼吸速率、减缓果实硬度和可滴定酸含量的下降,保鲜效果优于延迟预冷处理,这2种处理方式均能减轻果实低温伤害的发生,但却加重了苦痘病的发生;与对照相比,结合处理组虽然也加重了苦痘病的发生,但却完全抑制了冷害的发生,并保持了较好的贮藏品质。     

采后1-MCP和热处理对红富士苹果生理变化和贮藏品质的影响

采用1-MCP(浓度为1μL/L,18h)、热空气(HA)38℃-96h及2者结合对富士苹果进行处理,处理后的果实置于(0±0.5)℃条件冷藏4个月,然后置于20℃条件下7d(模拟货架期)。试验发现在整个贮藏过程中所有处理组均能抑制果实的乙烯释放速率和呼吸强度,减缓果实硬度的降低。热处理组对固酸比的上升有显著作用,保持了较高的非水溶性果胶含量和较低的水溶性果胶含量。热处理在贮藏过程中对于果实硬度的保持与对照组相比起到一定的作用,但加速了果皮中叶绿素含量的降解。1-MCP处理组能够较好地抑制果实果皮的褪绿,保持果皮中较高的叶绿素含量,初期抑制细胞膜透性的上升,延缓果实的后熟衰老。结合处理组较好地保持果实膜的完整性,减缓了由热处理所引起的果皮叶绿素的降解,并保持较高的含酸量,保持了较好的风味品质。     

Critical ethylene exposure for Capsicum annuum ‘Janne’ is dependent on an interaction between concentration,duration and developmental stage

Summary

Two ethylene experiments were designed to show the reaction of the pot plant Capsicum annuum ‘Janne’ to ethylene and to define the critical level of ethylene exposure. The ethylene exposure consisted of 72 h of darkness at 19°C, an ethylene duration of 6–72 h and ethylene concentrations of 0.05–5.0 µl l^?1. After the plants had been exposed to ethylene they were placed in a post-production evaluation room. The response of capsicum to ethylene, as expressed by leaf and fruit abscission, was dependent on developmental stage, duration of ethylene exposure and ethylene concentration. Leaves were the most ethylene-sensitive plant parts, followed by the green and maroon fruits. Ethylene did not affect the rate of development into red fruits. The most developed plants were less sensitive to ethylene. Capsicum is very sensitive to ethylene, e.g. there was significant abscission of leaves after exposure to an ethylene concentration of 1.0 µl l^?1 for 12 h and a significant abscission of leaves and green fruit after exposure to 0.05 µl^?1 for 72 h. A critical ethylene exposure is suggested, dependent on plant sensitivity, duration of ethylene exposure and ethylene concentration.     

Erh?hung der Temperatur bei der Apfellagerung durch Einsatz von 1-MCP

The investigations should purify whether the temperature during apple storage can be increased by application of 1-MCP to decrease energy consumption and costs. The investigations were carried out over 2 years with the following treatments: Year 1: The apple cultivars ‘Elstar, Elshof’ and ‘Gala, Must’ were investigated. For both cultivars 3 different storage temperatures (1, 2 and 4°C) with and without application of 1-MCP were examined. Each temperature and 1-MCP treatment was investigated both under CA-/ULO-conditions with 1.5% O₂ and 2% CO₂ and in cold storage with normal atmosphere. Year 2: The apple cultivars ‘Jonagold, Jonica’ und ‘Golden Delicious, Weinsberg’ were investigated. For both cultivars 3 different storage temperatures (1, 2 and 4°C) with and without application of 1-MCP were examined. Each temperature and 1-MCP treatment was investigated both under CA-/ULO-conditions with 1.5% O₂ and 3% CO₂ and in cold storage with normal atmosphere. The influence of temperature, storage atmosphere and 1-MCP application on fruit firmness, soluble dry matter (sugar) and fruit acid was investigated on 6 dates (September to October in the first year) respectively on 5 dates (October to March) during the storage period. Following results were obtained:

1. In the first year storage temperature did not influence the content of soluble dry matter of both cultivars. Application of 1-MCP led to a less decomposition of soluble dry matter. In the second year the content of soluble dry matter decreased slightly with increasing temperatures. A clear positive effect of 1-MCP-application was not noticeable. Altogether an increase of storage temperature has no or only a small influence of the content of soluble dry matter. 1-MCP can slow down the decomposition of soluble dry matter.
2. An increase of storage temperature had no or only a small influence of fruit firmness. With increasing storage temperature fruit firmness decreased slightly.1-MCP application led to a higher fruit firmness, especially during cold storage in normal atmosphere. In both years all cultivars showed a same or higher fruit firmness at 4°C with 1-MCP application under CA-/ULO-conditions as at 1°C without 1-MCP application under CA-/ULO-conditions.
3. An increase of storage temperature had no or only a small influence of the content of fruit acid.1-MCP application under CA-/ULO-conditions reduced the decomposition of fruit acid. In both years usually all cultivars showed a same or higher content of fruit acid at 4°C with 1-MCP application under CA-/ULO-conditions as at 1°C without 1-MCP application under CA-/ULO-conditions.

The results show that an increasing of storage temperature under CA-/ULO-conditions and with 1-MCP application has no negative influence on fruit quality in comparison to fruits which were stored under CA-/ULO-conditions at low temperatures without 1-MCP application.     

Preharvest applications of ethephon reduce superficial scald of ‘Fuji’ and ‘Granny Smith’ apples in storage

In 1989 and 1990, preharvest applications of 2-chloroethyl phosphonic acid (ethephon) at dosages from 50–400 mg 1’1 were applied to ‘Fuji’ and ‘Granny Smith’ apples. In 1989, the greatest reduction in scald after storage on both ‘Fuji’ and ‘Granny Smith’, relative to the untreated control resulted from applying 400 mg 1^?1 ethephon five weeks before harvest and was 45% and 55% of controls, respectively. On ‘Granny Smith’ 400 mg 1^? was also effective when applied three weeks before harvest. In 1990, preharvest applications of ethephon at either 200 or 400 mg 1^?1 reduced scald in both cultivars relative to the controls. Ethephon applied six weeks before harvest had no dosage effect on scald reduction after storage. There was no consistent effect on fruit maturity at harvest from any treatment in either year, and no effect on quality of fruit out of storage.     

Fruit quality and respiration of ‘McIntosh’ apples in response to ethylene,very low oxygen and carbon dioxide storage atmospheres

Storage of ‘McIntosh’ Apples (Malus domestica Borkh.) in a controlled atmosphere (CA) with very low O₂ (1.5% CO₂ + 1.0% O₂, 2.8°C) retained greater fruit firmness and titratable acids during storage and during subsequent air storage than apples stored in conventional CA (5.0% CO₂ + 3.0% O₂, 2.8°C). The rate of firmness loss during subsequent 0°C air storage decreased with length of storage in CA. Storage of apples in very low O₂ for 40 or 80 days decreased the rate of firmness loss in subsequent 0°C air storage as compared to the rate of firmness loss in conventional CA fruit, but the rate of firmness loss in 0°C air storage subsequent to 160 or 320 days of conventional CA was significantly less than the loss in similar fruit stored in very low O₂ atmospheres.A modified atmosphere with 1.0% O₂ decreased the rate of C₂H₄ accumulation in storage, and fruit production of both C₂H₄ and CO₂ after storage opening in comparison with similar fruit in conventional CA. The accumulation of C₂H₄ in storage chambers was increased with increasing O₂ levels, but the rate of increase depended upon the CO₂ level. C₂H₄ storage accumulation was stimulated by the presence of CO₂ at 0.5% O₂, but was suppressed by CO₂ when 3.0% O₂ was maintained.Retention of fruit firmness and titratable acids in apples stored in 1.5% CO₂ + 1.0% O₂ were insensitive to very low (0.231 ml l^?1) or very high (2440 ml l^?1) C₂H₄ levels in storage. Scrubbing C₂H₄ (0.304 ml l^?1) from chambers held at 5.0% CO₂ + 3.0% O₂ resulted in significantly firmer fruit after storage, but this effect was not significant after shelf life of 7 days at 20°C.     

Influence of Melatonin Treatments on Fruit Quality and Storage Life of Sweet Cherry cv. ‘Sweetheart’

The study was carried out to determine the effect of melatonin on quality and postharvest life of sweet cherries (Prunus avium L.) cv. ‘Sweetheart’ during storage. The fruits were dipped at different concentrations of melatonin (0, 250, 500 and 1000?µmol l^?1 for 10?min) and distilled water as control. The changes of sweet cherries were assessed at 7?day intervals by evaluating the following quality parameters: firmness, soluble solids content, titratable acidity, respiration rate, color values (L* and chroma), ascorbic acid content, total anthocyanin content, total phenolic content, and antioxidant activity. The results showed that increasing the dose to 1000?µmol l^?1 melatonin had a remarkable effect on maintaining the quality of sweet cherry. 1000?µmol l^?1 and 500?µmol l^?1 melatonin treatments significantly inhibited the decrease in firmness, ascorbic acid, total phenols, total anthocyanin, antioxidant content and reduced color changes and respiration rate. However, the total soluble solids content and titratable acidity of the fruit were not influenced by melatonin applications. These findings indicate that melatonin treatment may be effective in maintaining quality and bioactive compounds of sweet cherry fruit.

     

Modified atmosphere packaging of minimally processed avocado cv. ‘Booth 7’

Summary

Avocado fruits were washed with 200 µg l^–1 active chlorine, partially ripened to a firmness of about 12.5 ± 0.6 kg cm^–2, and sliced. Fruit slices were dipped in 1.0 mg l^–1 citric acid and 200 µg l^–1 ascorbic acid maintained at 4°–6°C for 2 min, dried with tissue paper and packaged in 0.05 mm or 0.075 mm-thick low density polyethylene (LDPE) at a 1:1 surface area to product weight ratio (cm² g^–1). Sodium chloride (1 g) sealed in 0.075 mm-thick poly-coated paper pouches was included in the packages for moisture absorption. In-package O₂ and CO₂ concentrations, as well as the ethanol and acetaldehyde concentrations, firmness and lightness (L^* value) of the tissue slices were measured during storage for 10 d. The sensory attributes of the modified atmosphere (MA)-packaged slices were compared with fresh fruit slices. In-package O₂ concentrations fell from 14.1% to 6.3% and CO₂ concentrations rose from 4.7% to 4.9%. Ethanol concentrations increased from 9.0 to 32.1 µg g^–1 and acetaldehyde from 1.1 to 3.8 µg g^–1 during storage from day-1 to day-10 in the 0.05 mm-thick LDPE with sodium chloride moisture absorbers. In-package concentrations of O₂ fell from 10.8% to 3.8% and CO₂ rose from 3.8% to 8.1%, while ethanol concentrations increased from 10.0 to 40.4 µg g^–1 and acetaldehyde from 1.3 to 4.7 µg g^–1 during storage from day-1 to day-10 in the 0.075 mm-thick LDPE with sodium chloride moisture absorbers. The L^* value and sensory attributes of avocado slices packaged in 0.05 mm-thick LDPE, with moisture absorbers, were not significantly different from fresh slices, indicating the effectiveness of these MA conditions. Regardless of packaging conditions, avocado slices reached the firmness values of 5.8–6.3 kg cm^–2 required for the ‘table-ripe’ stage on day-10 in storage. Therefore, packaging of ‘Booth 7’ avocado slices in 0.05 mm-thick LDPE with sodium chloride as a moisture absorber resulted in a storage-life of 10 d at 8°C and 90 ± 2% RH.