Slowing the deterioration of mango fruit during cold storage by pre-storage application of oxalic acid

Summary

The effects of pre-storage application of oxalic acid (OA) on the incidence of decay and ripening in mango fruit, and its physiological effects on the peel and flesh of mango were investigated after mango fruit (Mangifera indica L. cv. Zill) were dipped in 5 mM OA for 10 min at 25ºC then stored at 14º ± 1ºC for 5 weeks. In addition, spore germination and mycelium growth of Colletotrichum gloeosporioides Penz. on potato dextrose agar (PDA) media containing different concentrations of OA were measured. Application of OA decreased the incidence of decay and delayed the ripening process in mango fruit during cold storage. However, there was no reduction in fruit quality, as judged by the soluble solids content (SSC) and titratable acidity (TA) of fruit ripened at 25ºC for 3 d, following 3 weeks of cold storage. Oxalic acid-treatment resulted in decreased lipoxygenase (LOX) activity and increased superoxide dismutase (SOD) activity in the peel, and increased ascorbate peroxidase (APX) activity in both the peel and the flesh, coincident with a decrease in reactive oxygen species (ROS).At or above 5 mM, OA with unaltered (natural) pH or after neutralisation, also inhibited C. gloeosporioides development in vitro. It is suggested that the physiological effects of OA, in decreasing LOX activity and enhancing defense against oxidation damage, contributed to delaying the ripening process in mango fruit during cold storage. Thus, pre-storage application of OA could be a promising method to suppress post-harvest deterioration and extend the shelf-life of refrigerated mango fruit, possibly due to a combination of its physiological effect in delaying the ripening process, coupled with an inhibition of the development of pathogens such as C. gloeosporioides.     

气调贮藏对富士苹果采后生理 及果肉褐变的影响

气调对比试验结果表明气调贮藏可显著抑制富士苹果果实硬度的下降,减少内源乙烯含量,贮藏寿命达8个月,并可保持其品质;富士苹果果肉褐变的主要原因是CO     

Response of the phenylpropanoid pathway to Venturia inaequalis infection in maturing fruit of ‘Braeburn’ apple

Summary

This study investigated the activities of key enzymes in the phenylpropanoid pathway and the accumulation of phenolic products in apple peel in response to infection with Venturia inaequalis [(Cooke) G. Wint.]. We compared healthy apple peel with apple peel showing symptomatic scab lesions, and with peel tissue from 1 – 2 mm around the scab lesions in fruit 1 month before maturity [140 d after full bloom (DAFB)] and at physiological maturity (175 DAFB). Infection with V. inaequalis enhanced the synthesis of some phenolic compounds. Compared to healthy peel, scab lesion tissue had ≤ 3.1-times higher hydroxycinnamic acid content, ≤ 1.3-times higher dihydrochalcone content, and ≤ 3.9-times higher flavan-3-ol content. Scab lesions showed slightly higher phenylalanine ammonia-lyase, chalcone synthase, chalcone isomerase, flavonol synthase, and dihydroflavonol 4-reductase activities. The total amount of phenolics remained relatively stable between the two sampling dates, except for epicatechin and caffeic acid which decreased in amount toward fruit maturity, and levels of catechin which increased in more mature fruit. During fruit maturation, only chalcone synthase and chalcone isomerase activities decreased in all tissues examined. This study showed that the phenylpropanoid pathway in apple fruit peel changed significantly following infection with the apple scab pathogen.     

A modified chemiluminescence method for hydrogen peroxide determination in apple fruit tissues

Hydrogen peroxide (H₂O₂) is one of the important by-products produced by plant and fruit tissues during normal metabolism as well as under stress conditions. Evidence suggests that it is actively involved in many physiological activities in plants, including ripening, senescence and the development of disorders. Quantitative measurement of H₂O₂ in fruit has been a challenge due to variations in methodologies, and their sensitivities and interferences present in plant samples. Among the currently used methodologies, chemiluminescence (CL) is one of the most promising, due to its high specificity and sensitivity. However, direct application of CL methods developed for leaf analysis is not suitable for fruit, especially fruit peel tissues, possibly due to interfering compounds in fruit tissues. In this study, evaluation of the efficiency of removal of interfering compounds by PVP, PVPP and activated charcoal revealed that the PVPP is the most effective compound to remove the interference. This modified protocol can measure H₂O₂ content in apple peel and flesh tissues. ‘Red Delicious’ apple peel and flesh tissues were measured with amount of 1.48 and 1.03 μmol/g FW, respectively. The established protocol can also be used for a wide variety of tissues in addition to apple fruit, including strawberry tissues (fruit, calyx and leaves) and spinach leaves. This protocol was applied to determine the H₂O₂ concentration in 1-MCP and DPA treated apples after 5 months of storage, but no significant difference in H₂O₂ in those samples was found. Direct comparison of CL with a commercial hydrogen peroxide measurement OXIS kit was also made. The challenges to accurately assay H₂O₂ in fruit/plant tissue were discussed.     

Harvest parameters to improve the storability of high quality ‘Reinette du Canada’ apple

Summary

‘Reinette du Canada’ apple (Malus domestica Borkh.), which has been declared a Protected Designation of Origin (PDO) product throughout the European Community, is severely affected by bitter pit during storage, but increasing demand for organic produce requires chemical post-harvest treatments to be replaced with organic practices. The objective of this work was to determine the optimum stage of fruit maturity to improve the storability of high quality ‘Reinette du Canada’ apple during storage without applying post-harvest treatments. Seasonal conditions influenced fruit quality and the occurrence of storage disorders in ‘Reinette du Canada’. Harvest maturity also influenced the quality of ‘Reinette du Canada’ apple during storage, with later harvests reducing the development of bitter pit and increasing the soluble solids content:titratable acidity (SSC:TA) ratio. This study suggests that the SSC:TA ratio was a useful parameter for determining the optimum harvest maturity for high acidity, ‘Reinette du Canada’ apple. High quality fruit were obtained after long-term storage when the SSC:TA ratio exceeded 11.0, and fruit firmness at harvest exceeded 90 N. If these thresholds were not achieved, the quality of harvested ‘Reinette du Canada’ apples may not be sufficient to market fruit with the PDO designation. The results of our study also suggested that skin hue angle (hº) measurements may provide a quick and useful index that could replace fruit firmness measurements in the future.     

1-MCP处理对采后‘澳洲青苹’苹果叶绿素降解的影响

【目的】以‘澳洲青苹’苹果为试材,研究1-甲基环丙烯(1-MCP)对果实采后叶绿素降解代谢的影响,为果实采后贮藏、保鲜及保绿技术提供新的理论基础。【方法】采用1μL·L^-11-MCP处理‘澳洲青苹’苹果果实,定期测定果实色泽、乙烯释放量和呼吸强度,通过高效液相色谱法(HPLC)对果皮中的叶绿素及其降解代谢产物进行定性定量分析,并采用实时荧光定量PCR技术检测叶绿素降解途径中关键基因的表达水平。【结果】1-MCP处理显著延缓‘澳洲青苹’果皮颜色转变,降低乙烯释放量和呼吸强度。1-MCP处理能保持果皮叶绿素a、b含量处于较高水平,并抑制脱镁叶绿素a和脱镁叶绿酸a的生成。叶绿素降解相关基因MdSGR、MdHCAR、MdPPH和MdNYC1的表达量受到1-MCP的调控,1-MCP抑制基因MdPAO和MdRCCR的表达,推迟叶绿素降解代谢的下游反应;MdPAO表达量与果皮色泽和叶绿素含量显著相关。【结论】1-MCP可调节叶绿素降解途径相关基因表达水平来控制代谢产物的降解和生成,从而延缓果皮叶绿素降解,其中,MdPAO是调控叶绿素降解的关键基因。     

Biochemical and physiological changes during chlorophyll degradation in lime (Citrus aurantifolia Swingle cv. ‘Paan’)

Summary

Lime (Citrus aurantifolia Swingle cv. ‘Paan’) native to South East Asia, has a distinct flavour and quality characteristics. Maintenance of the green colour in the peel of lime is a desirable quality attribute during storage. Post-harvest chlorophyll degradation in lime was studied in fruit stored at room temperature (30°C) at a relative humidity (RH) of 70 – 85%. Within 7 d of storage, the total chlorophyll content decreased to 53.9% of its initial level. The highest chlorophyllase activity (1.68 units mg^–1 protein) was observed after 4 d of storage and declined thereafter. Peroxidase activity differed from chlorophyllase activity and increased significantly to 6.25 units mg^–1 protein after 9 d of storage, (i.e., at the late maturity stage). Respiration rate and 1-aminocyclopropene-1-carboxylic acid (ACC) oxidase activity did not significantly affect the chlorophyll degradation process in lime.The total nitrogen content of lime peel was inversely correlated with its chlorophyll content. A higher soluble protein content was observed in yellow peel than in mature green peel. A colour index chart was developed for maturity stages 1–4 in lime based on peel colour changes from mature green to full-yellow, and its correlation with chlorophyll content and fruit quality attributes.     

Effects of post-harvest calcium chloride or salicylic acid treatments on the shelf-life and quality of apricot fruit

Summary

The purpose of this work was to estimate the effects of post-harvest calcium chloride or salicylic acid treatments on the physicochemical characteristics and shelf-life of apricot (Prunus armeniaca L.) ‘Asgar-Abad’ fruit stored at 1ºC in a normal atmosphere for 21 d after harvest. Fruit were dipped in deionised water (control), or in 40, 60, or 80 mM CaCl₂, or in 1.0, 2.0, or 3.0 mM salicylic acid (SA) for 10 min.Total soluble solids (TSS) contents, titratable acidity (TA), ascorbic acid contents, total phenolics contents, and total anti-oxidant activity were determined 7, 14, or 21 d after each treatment. Fresh weight (FW) loss, titratable acidity, and TSS contents were improved by all treatments. Fruit treated with 3 mM SA exhibited the highest phenolics content during the storage period. At the end of the storage period, the highest values of TSS were observed in the 2.0 mM and 3.0 mM SA treatments. This experiment revealed that post-harvest treatment with SA or CaCl₂ prolonged the storage-life and preserved the valuable marketing characteristics of apricot fruit, presumably because of their inhibitory effects on fruit softening, ripening, and senescence. Over 21 d in cold storage, 2.0 mM SA was found to be the best treatment to maintain fruit quality in terms of FW loss, while 60 mM CaCl₂ was optimal for achieving high ascorbic acid concentrations and enhancing the anti-oxidant capacity of fruit.     

The interaction of copper and zinc with calcium in apple fruit

Analysis of ions in cortical tissue of fruit after post-harvest dips in calcium with or without 0.2 and 2% copper or zinc, and after subsequent storage, show that calcium levels were reduced by the presence of both metals. Uptake of ⁴⁵Ca into both peel and cortical tissue disks was also reduced by copper and zinc. The reduction is probably due to exchange of copper and zinc with calcium, and increased membrane permeability due to the presence of these metals. These results do not support suggestions that calcium uptake is stimulated by copper or zinc in apple fruit.     

Cultivar variation in apple peel and whole fruit phenolic composition

The quali-quantitative distribution of phenolic compounds varies considerably between apple flesh and peel, but the concentration of phenolics is substantially higher in the peel than flesh. Because the peel comprises only a small percentage of the entire fruit weight, its significance as a donor of phenolics is disputable. We assessed the contribution of the peel to the total phenolic yield of 19 apple cultivars. Calculations were based on the weight of the whole fruit and the peel (which is frequently discarded) and the concentration of individual phenolic compounds. On average, 8, 24, 32, 50 and 66% of chlorogenic acid, (+)-catechin, (−)-epicatechin, phloridzin, and rutin, respectively, were present in the peel, which constitutes about 6–8% of the whole apple weight. With the exception of chlorogenic acid, 50% or more, on average, of the above phenolics were present in the peel of ‘Granny Smith’, ‘Idared’, ‘Red Rome’, ‘Jonamac’ and ‘Gloster’ apples; the highest percentage was found in ‘Starking Delicious’ apple peel (82%). The lowest peel contribution to total phenolic content per whole apple ranged between 26 and 29% and was observed in ‘Pilot’, ‘McIntosh’ and ‘Prima’ apples. Presented results may be useful for further investigations of the relationship between phenolics and agronomical parameters or future selection of apple genotypes having improved nutritional quality when consumed as fresh or as processed apple products.     

Post-harvest putrescine treatments extend the storage-life of apricot (Prunus armeniaca L.) ‘Tokhm-sefid’ fruit

Summary

The aim of this study was primarily to increase the storability of apricot which is normally a very short storage-life stone fruit. Polyamines are well-known to improve the storability of many horticultural crops. The effect of exogenously applied putrescine on the post-harvest storage-life of apricot (Prunus armeniaca L.) ‘Tokhm-sefid’ fruit at 2°C was therefore investigated. The rate of ethylene production, fresh weight (FW) loss, tissue firmness, soluble solids content (SSC), titratable acidity (TA), and the pH of fruit were determined 5, 10, 15, 20 and 25 d after the beginning of storage. Overall, the application of putrescine caused a reduction in ethylene production, as well as an increase in fruit flesh firmness. SSC and pH were reduced, and TA was increased in putrescine-treated fruits. The loss of fruit FW was affected by putrescine in a concentration-dependent manner. Thus, fruit treated with higher concentrations of putrescine showed lower FW loss.     

Strawberry Yellows in the Variety Auchincruive Climax

Summary

Fresh ‘Mavra Markopoulou’ fig fruits, harvested close to a fully ripe state in October, were stored at ?1?C in either air or 2% O₂ (balance N₂) for 29.d. During storage in air the rates of O₂ uptake and ethylene production declined substantially and fruit weight loss increased up to 2.1%. Storage in 2% O₂ resulted in further reduction of O₂ uptake and ethylene production rates. The effects of storage conditions on ripening indices at 20?C in air were also investigated. Fruit stored in air showed decreased firmness, ethylene production rate and flesh colour lightness, but no significant or consistent changes in respiratory quotient, O₂ uptake and CO₂ production rates, soluble solids content, titratable acidity and other colour changes in peel or flesh were observed. In contrast, storage in 2% O₂ resulted in decreased respiratory quotient (although values remained above 1), O₂ uptake and CO₂ production rates and prevented fruit softening, loss of green peel colour and decrease in flesh lightness during post-storage at 20?C. All fruit were stored successfully under the above conditions, but 2% O₂ is recommended for better firmness retention during storage for longer than 8.d.     

苹果果实中类黄酮化合物的研究进展

 类黄酮是苹果果实中的一类主要多酚类物质, 对人体健康具有多方面的生理功能。已报道的苹果果实类黄酮达34种, 分属黄烷醇、黄酮醇、二氢查耳酮、花青苷和二氢黄酮醇5类。苹果果实中类黄酮的组成和含量因品种和果实部位而异, 通常果肉中的类黄酮种类和含量均明显少于果皮。苹果果实在发育、成熟和贮藏过程中类黄酮含量会发生变化。苹果果实类黄酮的测定普遍采用带二极管阵列检测器或紫外检测器的高效液相色谱仪, 并用质谱仪对类黄酮进行成分确认和结构鉴定。     

采前喷钙对中华寿桃采后贮藏品质及褐变的影响

通过生长期树冠喷施Ca(NO3)2,研究了采前喷钙对中华寿桃采后贮藏品质及其褐变的影响。结果表明,喷钙处理后中华寿桃果皮和果肉钙含量分别提高了11.5%和16.1%,果实硬度提高了7.8%,增强了果实贮藏过程中硬度的保持力,贮藏过程中可溶性固形物和可滴定酸含量及变化不受喷钙处理的影响(α=0.05);与对照相比,虽然处理果实呼吸高峰推迟1d出现,但喷钙处理对中华寿桃采后呼吸的抑制效果并不明显;此外,喷钙处理还提高了冷藏后货架期间果实总酚含量和多酚氧化酶活性,并且显著抑制细胞膜脂氧合酶的活性(α=0.05);采前喷施硝酸钙处理虽然没有明显抑制中华寿桃冷藏4周后货架期间果肉的褐化,但对抑制果实褐腐症状效果显著。     

Evaluating the effectiveness of different strategies for calcium application on the accumulation of calcium in apple (Malus × domestica Borkh. ‘Braeburn’) fruit

Summary

Orchards displaying calcium (Ca) deficiency are a common phenomenon worldwide, despite the presence of sufficient Ca in the soil and the plant. A 3-year trial was conducted between the 2007 – 2008 and 2009 – 2010 growing seasons to evaluate the contributions of soil and foliar Ca applications to Ca concentrations in ‘Braeburn’ apple (Malus × domestica Borkh.) fruit. Ca(NO₃)₂ (Calflo; Yara Africa, Fourways North, South Africa) was applied as six separate foliar sprays until run-off. Applications were made at 1-week intervals between approx. 21 – 70 d after full bloom (DAFB) at 6.75 ml l^–1. Soil applications of Ca (Tropicote^TM; International ASA, Oslo, Norway) at 300 kg ha^–1 were applied at fruit set, or after harvest, according to standard practice. Mineral analysis was conducted to assess the soluble Ca concentrations of whole fruit (without pips and stalks), to quantify the contribution of foliar sprays or soil-applied Ca. Fruit Ca concentrations were maintained at satisfactory levels (4.5 mg Ca 100 g^–1 FW) at harvest by applying a series of six foliar sprays early in the season (for all seasons) during the trial period. Fruit Ca concentrations at 80 DAFB were highest in the treatments with foliar applications of Ca. In 2009 – 2010, Ca concentrations in apple fruit were lowest (8.38 mg 100 g^–1 FW) for soil application of Ca at fruit set. Ca applications to soil after harvest in the previous season, and soil applications shortly after fruit set in the current season, did not significantly increase Ca concentrations in current-season fruit, providing soil Ca levels were above the minimum requirement for apple trees. A possible explanation is that apple trees regulate their uptake of Ca through the roots when soil Ca is available in sufficient quantities. This confirms the importance of active root growth for efficient Ca uptake by apple trees when applying Ca to the soil.     

Total Phenolics Content,Antioxidant Capacity,Physicochemical Attributes,and Browning Susceptibility of Different Apple Cultivars for Minimal Processing

The total phenolics content, browning susceptibility, antioxidant capacity, and other physicochemical attributes of five cultivars of apple with different chilling hours requirements were studied to be minimally processed. Granny Smith (GS) and Red Delicious (RD) cultivars (high chill requirement), and Caricia (C), Eva (E), and Princesa (P) cultivars (low chill requirement) were studied. The flesh color, firmness, juiciness, pH, acidity, soluble solids, and flesh browning development, and total phenolics content and antioxidant capacity in flesh and peel were determined. All attributes were significantly different (p ≤ 0.001) among cultivars. RD showed the highest values of soluble solids and pH, and GS, the lowest. GS and P had the highest values of firmness and juiciness. GS, P, and E showed the lowest browning development. RD had the highest phenol content in flesh, followed by E and C. Phenolic content in peel was 2–5 times higher than in flesh for all varieties. The antioxidant capacity of RD flesh was higher than the other four apple cultivars. The antioxidant capacity of the apple peel was 2–4 times higher than the flesh, being RD the highest, followed by C, GS, and P with 50% less. Considering the lower browning development, and higher values of firmness and juiciness, GS and P would be the most suitable cultivars for minimal processing. If fresh-cut apples are not peeled, GS and P would increase their phenolic content in 28–56% and their antioxidant capacity in 65–78%.     

采前钙处理对‘菊黄’桃果实品质和耐贮性的影响

通过对加工桃果实采前30d喷钙处理,研究不同浓度钙处理对贮藏期间加工桃果实生理和品质变化的影响。结果表明,采前喷施不同浓度的钙处理均能够抑制细胞膜透性的增大,降低呼吸强度和乙烯释放量,抑制多酚氧化酶（PPO）的活性,保持果实硬度和品质。其中,采前喷施1．0％和1．5％钙处理能够明显地提高加工桃果实的硬度,对延缓加工桃贮藏期间果实后熟、减轻果肉褐变和保持果实品质的效果最好。     

采后钙处理对苹果品质和钾离子外渗的影响

真空渗入4%和6%氯化钙的辽伏苹果在处理后的12天中,果肉硬度均明显地高于对照和渗入滴水的果实。果肉硬度的变化与使用氯化钙溶液的浓度呈正相关。氯化钙处理后,果肉组织的钾离子外渗受到抑制。     

套袋对苹果果实钙素吸收与分布的影响

以红富士苹果(Malus domestica Borkh.cv.Fuji)为试材,进行了套袋处理,以不套袋果实为对照,测定其果实的Ca含量,研究套袋对果实钙素吸收与分布的影响。结果表明,果实套袋后,在花后40～90d,整果钙吸收量高于对照果实;从花后120d开始,对照果实整果钙含量一直高于套袋果实。此外,苹果果实在整个生长发育过程中对Ca都有吸收,花后40d内,苹果果实吸收整果钙含量的20%左右;从花后40d(套袋)到90d,果实钙吸收量迅速升高,对照果实可吸收整果钙含量的66.1%,套纸袋果实可吸收整果钙含量的73.8%;此外,在果实的成熟期仍有少量的钙吸收。果实套袋后,果实各个部分的钙含量变化与对照果实相比,果皮中钙含量明显低于对照果实,而果肉和果心的钙含量却高于对照果实。