Extending shelf-life of persimmon (<Emphasis Type="Italic">Diospyros kaki</Emphasis> L.) fruit by hot air treatment

‘Qiandaowuhe’ persimmon fruits (Diospyros kaki L.) were stored at 20 °C after exposed to 20 °C (control), 44 °C (T ₄₄), 48 °C (T ₄₈) or 52 °C (T ₅₂) hot air for 3 h, respectively. Firmness, weight loss, peel color, total carotenoids content, soluble solids content (SSC), titratable acidity (TA), respiration, and ethylene production and cell wall hydrolysis enzymes activities were monitored to determine the efficacy of hot air treatment in delaying persimmon fruit ripening. Results showed that ‘Qiandaowuhe’ persimmon fruit displayed a typical climacteric pattern of respiration and ethylene production. Peak of CO₂ and ethylene production was observed after 4 days. Fruit softening was accompanied by a progressive increase in weight loss, total carotenoids content and decrease in h°. The activities of pectinmethylesterase (PME) and polygalacturonase (PG) sharply increased and reached maximal values after 4 and 6 days, respectively. Hot air treatment significantly delayed the onset of climacteric ethylene production, respiration, PME and PG activities in persimmon fruit. Moreover, it also significantly retarded the increase in carotenoids content and SSC, while decreased the firmness, h°, and TA. The hot air treatment promoted fruit weight loss. The shelf-life of persimmon ripening increased 4 days by T ₄₄, and 6 days by T ₄₈ or T ₅₂. Results suggest that hot air treatments can greatly extend the postharvest life of ‘Qiandaowuhe’ persimmon fruit.     

Effect of 1-methylcyclopropene on ripening of postharvest persimmon (Diospyros kaki L.) fruit

Postharvest persimmon fruit (Diospyros kaki L. cv. Qiandaowuhe) was stored at 20 °C after being exposed to 3 μl l⁻¹ 1-methylcyclopropene (1-MCP) for 6 h or not (control). Several parameters (firmness, respiration and ethylene production, pectic substances and cell wall hydrolysis enzymes activities) were examined to determine the efficacy of 1-MCP treatment in delaying persimmon fruit ripening. Results showed that ‘Qiandaowuhe’ persimmon fruit displayed a typical climacteric pattern of respiration and ethylene production. Peak CO₂ production and ethylene production was observed on the fourth day. Fruit softening was accompanied by a progressive increase in water-soluble pectic substances (WSP) and a progressive decrease in chelator-soluble pectic substances (CSP) and alkali-soluble pectic substances (ASP). The activities of pectinmethylesterase (PME) and polygalacturonase (PG) started increasing sharply and reached a maximal value on days 4 and 6, respectively, and then decreased slowly. 1-MCP treatment delayed the onset of climacteric ethylene production and respiration in persimmon fruit, and also significantly retarded the activities of PME and PG during ripening at 20 °C. Consistent with the activity trends of cell wall hydrolysis enzymes, 1-MCP treatment also delayed the depolymerization of CSP and ASP and reduced the increase of WSP compared with the control fruit. Thus, application of 1-MCP can greatly extend the postharvest life of ‘Qiandaowuhe’ persimmon fruit.     

氯吡苯脲浸泡处理延缓采后芒果成熟和软化的生理机制

以采后‘贵妃’芒果为试材,使用10 mg/L氯吡苯脲（forchlorfenuron,CPPU）溶液对果实浸泡处理10 min,晾干后在室温（25 ℃）条件下贮藏8 d,研究CPPU浸泡处理对芒果果实贮藏期间成熟与软化相关生理指标的影响。结果显示：CPPU浸泡处理明显抑制了芒果果实的呼吸作用并推迟了果肉色泽、硬度、可溶性固形物质量分数和可滴定酸质量分数的变化;CPPU浸泡处理有效抑制了果实1-氨基环丙烷-1-羧酸合成酶和1-氨基环丙烷-1-羧酸氧化酶活性,导致乙烯释放量降低;此外,CPPU浸泡处理显著抑制了果实多聚半乳糖醛酸酶、果胶甲酯酶、β-半乳糖苷酶等果胶水解酶活性变化,并较大程度抑制了果胶多糖的增溶与解聚作用,故而延缓了果实的软化进程。结论：CPPU浸泡处理能有效延缓采后芒果果实的成熟与软化,从而延长果实货架寿命。     

SOFTENING AND BIOCHEMICAL CHANGES OF SAPOTE MAMEY FRUIT (POUTERIA SAPOTA) AT DIFFERENT DEVELOPMENT AND RIPENING STAGES

We investigated some of the physicochemical and biochemical factors associated with flesh softening of sapote mamey fruit during development and ripening. The activities of pectinmethylesterase (PME), polygalacturonase (PG) and β‐galactosidase (β‐GAL) enzymes were measured in fruits harvested at different development stages, and postharvest in two production seasons. The textural changes were most noticeable at the preclimacteric stage in ripening fruit. The water‐soluble pectin (WSP) increased at a different rate than firmness decreased. No correlation between PG or PME activity and changes in firmness was observed in ripening fruits, though a low correlation was seen between β‐GAL activity and softening in climacteric stage. Greatest loss of firmness occurred in climacteric stage. Fruit pulp softening was not dependent on a single enzyme activity.     

Effect of Non-Thermal Plasma-Activated Water on Fruit Decay and Quality in Postharvest Chinese Bayberries

Recently, non-thermal plasma-activated water (PAW) became a relatively new concept developed in the food industry. The effects of PAW on fruit decay, microbial loads, and quality of postharvest Chinese bayberry were investigated. Chinese bayberries were treated by PAW for 0.5, 2, or 5 min and then stored at 3 °C for 8 days. Experimental results show that all PAW treatments could reduce fruit decay by around 50 % compared to control at the end of storage. There was no dose-effect relationship between PAW treatment time and fruit decay. Meanwhile, a 0.5-min PAW treatment could remarkably decrease microbial population on Chinese bayberries during storage, and the maximum reductions reached around 1.1 log CFU/g both for bacteria and fungi at the end day of storage. Scanning electron microscopy results reveal that PAW could significantly change the morphology of microbial cells on Chinese bayberries. Moreover, physicochemical properties analysis of PAW demonstrates that the microbial inactivation of PAW is mainly attributed to the combined action of high oxidation reduction potential and low pH. Additionally, PAW-treated fruits exhibited markedly higher firmness, color index of red grapes, and total soluble solids than the control did at the eighth day. These results indicate that PAW might be a promising strategy to control fruit decay and maintain quality of Chinese bayberry during postharvest storage.     

QUALITY ATTRIBUTES, PECTOLYTIC ENZYME ACTIVITIES AND PHYSIOLOGICAL CHANGES DURING POSTHARVEST RIPENING OF NECTARINE

The postharvest ripening at 20C and 90–95% RH for 10 days of ‘Armking’ nectarine grown in a greenhouse was investigated over two seasons. Firmness, titratable acidity, ascorbic acid, pH and maturity index were all adequate to stablish the rate of ripening. However, soluble solids content and reducing and non-reducing sugars showed no significant changes. It took about 10 days for very early ripening fruit (100 g weight and 82 N firmness) and 6 days for normal early ripening fruits (115 g weight and 46 N firmness), both harvested at preclimacteric stage, to become eating ripe (near 20 N). Total weight loss and decay after 10 days was approximately 11%. During ripening there was a temporal coincidence among higher rates of ethyleneproduction, higher pectinmethylesterase (PME) and polygalacturonase (PG) activities, lower firmness and acidity and higher maturity index. PME and PG activities increased during ripening, with a highly negative linear correlation between activities of the two enzymes and firmness. In very early ripening fruit, PME activity was more closely related to softening than PG, whereas in normal early ripeningfruit, PG activity was slightly more closely linked to the loss offirmness than PME.     

Cell wall break down of pitanga fruit (Eugenia uniflora L.) is associated with pectic solubilisation and softening

Pitanga fruit stands out for its exotic flavour and antioxidant properties. The objective of this work was to evaluate changes in the physical, chemical and biochemical variables of red pitanga variety, in four stages of development (green, yellow, orange and red) and associate them to the cell wall break down. Analysis of pH, titratable acidity, soluble solids, firmness, soluble pectin, pectinamethylesterase (PME), polygalacturonase (PG), cell wall swelling and microstructure were performed. pH and levels of soluble solids and soluble pectin increased, in addition to the cell wall swelling and reduction of firmness, throughout the development of pitanga. From the SEM, it was possible to observe the degradation of the fruit cell wall during ripening, suggesting mainly the degradation of pectic polysaccharides, verified by the solubilisation of these substances. PG and PME enzymes were not active, which suggests that other enzymes may be associated with the cell wall break down.     

杨梅果实采后热空气处理条件的优化

采用响应曲面法研究了不同温度-时间组合的热空气处理对"乌种"杨梅果实采后贮藏品质的影响,并对热空气条件进行了优化。结果表明:当热处理温度为48.5℃,处理时间为173 min时,有最优贮藏保鲜效果:杨梅果实于1℃下贮藏7 d再转移至20℃下模拟货架期放置1 d后的腐烂指数为18.81%、硬度为3.31 N、Vc含量为5.25 mg/kg(鲜重)、固酸比为16.42。     

EFFECT OF GAMMA IRRADIATION ON SOFTENING CHANGES AND ENZYME ACTIVITIES DURING RIPENING OF PAPAYA FRUIT

The aim of this work was to study the role of cell wall and ethylene related enzymes to papaya fruit firmness. Irradiation treatment was used as an imposed stress to cause changes in firmness. Physiologically mature papaya fruits were irradiated (500 Gy) and allowed to ripen at 22C and 90% RH. Polygalacturo‐nase (PG), pectinmethylesterase (PME), βgalactosidase, cellulose and 1‐aminocyclopropane‐1‐carboxylate oxidase (ACC‐oxidase) activities were followed during ripening and correlated to changes in firmness, skin and pulp color, respiration and ethylene production. The firmness of irradiated fruits was retained at least 2 days longer than in normal fruits and also had a slower rate of softening. Total soluble solids (d?Brix), cellulase activity and ethylene production were not altered by irradiation treatment. The activity patterns of PG, PME and β‐galactosidase were related to pulp softening and affected by irradiation. ACC‐oxidase activity was influenced by irradiation treatment, but its changes were not temporally related to those in firmness. It was concluded that irradiation had no direct effect on firmness but it acted by altering the ripening induced synthesis of cell wall enzymes, mainly PME.     

1-MCP 与植酸处理对草莓果实采后生理品质的影响

采用1-甲基环丙烯(1-MCP)和植酸对草莓进行不同处理,通过追踪测定其贮藏期间的质量损失率、硬度、可溶性固形物(soluble solids content,SSC)、呼吸强度、维生素C(VC)、可滴定酸(titratable acidity,TA)和相对电导率等指标来研究不同处理对草莓的保鲜效果。结果表明：1-MCP和植酸处理可有效降低草莓的质量损失率和呼吸强度,推迟SSC出现峰值的时间,延缓其后熟衰老过程,抑制其硬度、TA和VC含量的下降;同时,1-MCP 和植酸复合处理比两者各自的单独处理都具有更好的效果,能显著改善草莓在贮藏期间的果实品质。     

A combination of hot air treatment and nano‐packing reduces fruit decay and maintains quality in postharvest Chinese bayberries

BACKGOUND: Chinese bayberry is susceptible to microbial decay during postharvest handling and storage. To search for effective alternatives to currently used fungicides for disease control, the efficacy of hot air (HA) treatment at 48 °C for 3 h alone or in combination with nano‐packing (NP) containing nano‐TiO₂ and nano‐Ag in controlling green mould decay caused by Penicillium citrinum and natural decay, and their effects on fruit quality in harvested Chinese bayberries were investigated in this study. RESULTS: The combined treatment of HA and NP resulted in a remarkably improved control of green mould and natural decay in Chinese bayberries compared with treatment of HA or NP alone. The in vitro growth of P. citrinum was significantly inhibited by individual HA or NP. In addition, HA in combination with NP showed interactive effect on inhibiting fruit respiration, ethylene production and membrane lipid peroxidation, and maintained higher fruit firmness and DPPH radical scavenging activity. CONCLUSION: These results suggest that a combination of HA treatment and NP may be a useful technique to reduce fruit decay and maintain quality in Chinese bayberries during postharvest storage and retail conditions. Copyright © 2010 Society of Chemical Industry     

一氧化氮对常温贮藏下芒果果实软化和细胞壁代谢的影响

为了探明一氧化氮(NO)抑制采后芒果软化的作用机理,将"台农"芒果果实在0.25 mmol/L硝普钠(SNP,NO供体)溶液浸泡处理20 min,常温(20±2) ℃贮藏20 d,定期测定果实硬度、细胞壁组分含量、细胞壁水解酶活性。结果表明,与未处理果实相比,SNP处理显著降低贮藏20 d内果实中多聚半乳糖醛酸酶(PG)活性(p<0.05),显著抑制贮藏10 d内果实纤维素酶(CX)(p<0.05)活性,极显著抑制β-半乳糖苷酶(β-Gal)和α-L-阿拉伯呋喃糖苷酶(α-L-Af)活性(p<0.01),但使贮藏15~20 d期间果实CX和β-Gal活性及贮藏第20 d的α-L-Af活性均显著增加(p<0.05)。SNP处理显著抑制贮藏5 d内果胶甲酯酶(PME)活性(p<0.05),但在贮藏10~20 d期间保持较高的PME活性(p<0.05)。此外,SNP处理极显著延缓原果胶和纤维素的降解(p<0.01),减少可溶性果胶含量的增加(p<0.05),从而降低贮藏期间果实硬度的损失。硬度与原果胶、纤维素含量均呈极显著正相关(p<0.01),而与CX活性呈显著负相关(p<0.05),与可溶性果胶含量、PG、β-Gal和α-L-Af活性均呈极显著负相关(p<0.01)。可溶性果胶含量与纤维素含量呈极显著负相关(p<0.01),而与α-L-Af活性均呈显著正相关(p<0.05),与PG和β-Gal活性均呈极显著正相关(p<0.01)。因此,采后SNP处理可以通过调节果实细胞壁降解酶活性,减少细胞壁组分的降解,从而延缓芒果采后软化,延长贮藏期。     

Cell Wall Changes and Partial Prevention of Fruit Softening in Prestorage Heat Treated ‘Anna’ Apples

Prestorage heat treatment (38°C for 4 days) retarded the softening of ‘Anna’ apple fruits during 0°C storage. Fruit softening of unheated apples during storage was accompanied by changes in pectic substances: a decrease in uronic acid content in the carbonate-soluble fraction and an increase in the water-soluble fraction. Heat treatment partially inhibited the degradation of uronic acids in the cell wall. The degree of pectin methylation in both heated and non-heated fruit decreased during storage. In heat treated apple fruit the content of galactose and arabinose in the cell wall decreased during storage; in non-heated fruit only galactose decreased. We suggest that the inhibition of solubilisation of the carbonate soluble pectin fraction is one of the main factors contributing to the firmness retention caused by heat treatment. The loss of both arabinose and galactose in heat treated fruits may also play an as yet undefined role in the effect of heat treatment on fruit softening.     

Pre‐ or post‐harvest applications of putrescine and low temperature storage affect fruit ripening and quality of ‘Angelino’ plum

BACKGROUND: Plum has a very short storage life. The role of pre‐ or post‐harvest applications of putrescine (PUT) and low temperature storage on fruit ripening and quality was investigated in plum fruit (Prunus salicina Lindl. cv. Angelino). RESULTS: Pre‐ or post‐harvest PUT treatments [(0.1, 1.0 or 2.0 mmol L^?1) + 0.01% Tween‐20 as a surfactant] delayed and suppressed the climacteric ethylene production and respiration rate irrespective of the method used to apply PUT. PUT‐treated fruit following low temperature storage (0 ± 1 °C; 90 ± 5% RH), at the ripe stage exhibited higher fruit firmness and titratable acidity (TA), while soluble solids content (SSC), levels of ascorbic acid, total carotenoids and total antioxidants were lower than in untreated fruit. Fruit both sprayed with PUT and stored in low temperature for 6 weeks, at the ripe stage showed reduced respiration rate, delayed changes in the SSC:TA ratio and levels of total carotenoids compared to post‐harvest PUT application. CONCLUSION: Pre‐harvest application of 2.0 mmol L^?1 PUT 1 week before the anticipated commercial harvest was more effective in delaying plum fruit ripening and can be used to extend the storage (0 ± 1 °C) life of plums for up to 6 weeks with minimum losses in fruit quality. Copyright © 2008 Society of Chemical Industry     

Effects of stage II and postharvest deficit irrigation on peach quality during maturation and after cold storage

Effects of regulated deficit irrigation (RDI) on the quality of a mid–late maturing peach (Prunus persica L Batsch cv Andross) were determined at commercial harvest as well as 1 week before (early pick‐up) and after 1 week of cold storage. Respiration and ethylene evolution were measured during 96 h on fruits sampled at early pick‐up and at harvest. Fruits from a well‐watered irrigation treatment (Control) were compared with a treatment of RDI during stage II of fruit growth (RDI‐SII) and with RDI applied postharvest (RDI‐PH). A fourth treatment received a combination of deficit irrigation applied during stage II and postharvest (RDI‐SII‐PH). Higher soluble solids content (SSC) amd SSC/titratable acidity (TA) ratio for RDI‐SII were already noted at early pick‐up and these differences were enhanced after cold storage (RDI fruits having higher SSC, lower TA and higher SSC/TA ratio than Control fruits). This improvement in quality (high SSC/TA ratio) was also correlated with a more reddish colouration in the fruit skin. Moreover, ethylene production indicated different behaviour of the physiological evolution for fruits from the different treatments. Copyright © 2004 Society of Chemical Industry     

Effects of 1-methylcyclopropene(1-MCP) on ripening and resistance of jujube (Zizyphus jujuba cv. Huping) fruit against postharvest disease

The effects of 1-methylcyclopropene (1-MCP) on senescence and induction of resistance against postharvest decay in jujube (Zizyphus jujuba cv. Huping) fruit were investigated in this study. The results indicated that, compared to control, 1-MCP at 1 μL L^?l depressed ethylene production by 28% and respiration rate by 30% at 24 h after treatment, resulting in effective delay in fruit senescence. 1-MCP treatment was beneficial for maintaining quality of jujube fruit stored both at 25 and 0 °C, retarding decline of firmness, vitamin C, titratable acidity (TA) and soluble solids content (SSC) which are important parameters for fruit quality evaluation during the storage periods. Moreover, 1-MCP effectively limited the development of lesion diameter of blue mold rot and significantly reduced the incidence of natural decay. The activities of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), catalase (CAT) and superoxide dismutase (SOD) were significantly induced after 1-MCP treatment. These findings indicate that the induced resistance in jujube fruit by 1-MCP is related with the increase of enzymes involved in scavenging of reactive oxygen species and enzymes associated with phenolics metabolism which produces highly toxic products against pathogen invasion. Our results suggest that 1-MCP has potential effect on maintaining the quality and extending postharvest life of jujube fruit.     

Changes in the quality of jaboticaba fruit (Myriciaria jaboticaba (Vell) Berg. cv. Sabará) stored under different oxygen concentrations

BACKGROUND: Jaboticaba (Myriciaria jaboticaba (Vell) Berg.) is a highly perishable Brazilian berry with a shelf life of only 2 days under ambient conditions. Low temperatures and controlled atmosphere (CA) have been used to extend the shelf life of perishable fruit. Thus the aim of this study was to determine the effect of CA with varying concentrations of oxygen (1, 5, 10, 15 and 21kPa) during cold storage (12.5 °C) of ‘Sabará’ jaboticaba fruit. RESULTS: Atmospheres with lower oxygen concentrations (1 and 5 kPa O₂) significantly reduced jaboticaba respiration rate. Fruit stored under these conditions had higher L* values, and titratable acidity (TA), and lower ratios of soluble solids content (SSC)/TA. However, at the lowest concentration of oxygen (1 kPa O₂), firmness decreased markedly compared to fruits stored at higher O₂ levels (P < 0.05). After only 2 days of storage at ambient temperature jaboticaba received a score of 1.6 (dislike strongly ? 1) compared to fruit stored under CA, which scored 7.4 (like moderately ? 7). After 9 days of storage, fruit from all treatments remained above the limit of acceptability (score 5) and were rated as 6.2. With respect to appearance, statistical differences between treatments were not observed. The total anthocyanin content was not affected by oxygen concentration but decreased 40.4% during CA storage. CONCLUSION: 'Sabará' jaboticaba fruit can be satisfactorily stored under atmospheres containing 5‐21 kPa O₂ at 12.5 °C for up to 6 days. Copyright © 2011 Society of Chemical Industry     

Effect of sucrose‐based polymers on quality of Satsuma mandarin fruit (Citrus unshiu Marc. cv. Miyagawa Wase)

In this study, the effects of an edible coating (sucrose‐based polymers, SBP) on postharvest fruit quality of Satsuma mandarin (Citrus unshiu Marc. cv. Miyagawa Wase) were investigated. All the fruit except the control was sprayed with SBP solution at a concentration of 0.1%, 0.3%, 0.5% and 1.0% (v/v), respectively, and then stored at room temperature (25 °C, 85% relative humidity) for 25 days. Results showed that 0.1%, 0.3% and 0.5% SBP treatment could significantly increase the soluble solids concentrations (SSC), vitamin C (Vc), total sugars, total carotenoids, the ratio of SSC to titratable acidity (TA) (SSC/TA), catalase (CAT), peroxidase (POD) and superoxidase dismutase (SOD) activities, while the decay rate, TA and polyphenol oxidase (PPO) activity were greatly reduced. In contrast, 1.0% SBP treatment resulted in fruit browning, despite maintaining fruit quality. Our present study provided the theoretical data for the practical application of the SBP on the citrus fruit quality of during postharvest storage.     

Prediction of postharvest dry matter, soluble solids content, firmness and acidity in apples (cv. Elshof) using NMR and NIR spectroscopy: a comparative study

Dry matter (DM), soluble solids content (SSC), firmness and acidity by proton nuclear magnetic resonance (NMR) T₂ relaxometry and near infrared (NIR) spectroscopy were investigated on a total of 390 apples (cv. Elshof). The fruit came from four different pre- or postharvest treatments and covered a large range of DM (11.4–20.0 %) and SSC values (10.5–18.3 °Brix). NIR was superior in predicting DM (R ² = 0.82) and SSC (R ² = 0.80), compared to NMR (R ² = 0.50 and R ² = 0.58). However, NMR relaxometry was able to detect multiple water populations assigned to different water pools in the apples and variation in the water distribution between different pre- and postharvest treatments. Differences in the mobility of the vacuole water (population T₂₄) were consistent with changes in fruit firmness. In conclusion, even though NIR is superior in predicting DM and SSC, NMR provides useful information about the intrinsic water state and its distribution in the fruit.     

海藻酸钠/纳米TiO2复合涂膜对采后番木瓜果实软化及细胞壁降解影响

为探究海藻酸钠/纳米TiO₂(sodium alginate/nano-TiO₂,SA/TiO₂)复合涂膜处理抑制采后番木瓜果实软化的作用机理,以“日升10号”番木瓜为试材,采用SA/TiO₂复合涂膜处理,研究采后番木瓜果实硬度、细胞壁组分含量和细胞壁水解酶活性的变化规律。结果表明,SA/TiO₂复合涂膜处理能有效地抑制采后番木瓜果实中多聚半乳糖醛酸酶(polygalacturonase,PG)、果胶甲酯酶(pectin methylesterase,PME)、纤维素酶(cellulase,Cx)和β-半乳糖苷酶(β-D-galaetosidase,β-Gal)活性,减缓原果胶和纤维素的水解,减少可溶性果胶的增加,从而保持较完整的细胞壁结构,维持果实硬度。因此认为,SA/TiO₂复合涂膜处理可延缓采后番木瓜果实的软化进程,提高果实耐贮性。