Effect of temperature manipulation during storage and ripening on firmness,extractable juice and woolliness in nectarines

‘Independence’ nectarines were stored at — 0.5°C for three or four weeks or at 3°C for four weeks or kept at room temperature for 18 h prior to storage for four weeks at -0.5°C. After cold storage, fruit from all treatments was ripened at 10°, 15°or20°C. In all treatments the percentage woolly fruit initially increased to high values and thereafter decreased with further ripening. The rate of increase and decrease in woolliness depended on the ripening temperature. A storage period of four weeks at — 0.5°C resulted more woolliness during subsequent ripening. Woolliness persisted longer after a four-week cold storage period than after a three-week one. When fruit was delayed at room temperature prior to cold storage, woolliness generally developed earlier and to a lesser extent during ripening. At all ripening temperatures initial storage at 3°C resulted in most woolliness extending over the longest period. In addition, browning of the meso- carp tissue occurred only in fruit cold stored at 3°C.-The delay period before cold storage decreased fruit firmness by 15.7 to 17.6 N. Except for fruit subjected to the delay period, the extractable juice in fruit of all treatments first decreased during ripening to low values then increased.     

The effects of storage temperature and fruit size on firmness,extractable juice,woolliness and browning in two nectarine cultivars

Fruit firmness, extractable juice, woolliness and browning of the mesocarp tissue in ‘Independence’ and ‘Flavortop’ nectarines stored at —0.5°, 3°, 5° and 7°C for four weeks were determined during ripening at 15°C. The firmness of both ‘Independence’ and ‘Flavortop’ during ripening decreased as storage temperatures increased. The percentage extractable juice after cold storage and during ripening varied considerably between cultivars and between the storage temperatures. The extractable juice of fruit stored at higher temperatures tended to increase during ripening, whereas fruit stored at lower temperatures tended to decrease first before increasing. At storage temperatures of —0.5° and 3°C both cultivars passed through a stage of woolliness during ripening, while less woolliness occurred after storage at 5° and 7°C. In both cultivars the percentage extractable juice during ripening was higher on average at storage temperatures of 5° and 7°C. Severe browning of mesocarp tissue in both cultivars occurred during ripening after storage at 3°C. The effect of fruit size on changes in firmness, development of woolliness and mesocarp browning in ‘Flavortop’ nectarines stored at — 0.5°C for four weeks and ripened at 15°C was also determined. Larger nectarines lost firmness more rapidly, woolliness occurred sooner and the mesocarp tissue was more prone to browning than smaller fruit during ripening.     

Maturity and water loss effects on avocado (Persea americana Mill.) postharvest physiology in cool environments

The influence of cold storage, increasing fruit maturity and water loss on the ripening physiology of ‘Fuerte’ avocado was investigated. Fruit cold stored for 28 d at 5.5°C always subsequently ripened faster than non-stored fruits of a similar maturity. Non-stored fruit showed an expected decrease in ripening time with increasing maturity. In cold stored fruit the relationship between ripening time and maturity was less clear. Cold stored fruit lost less water during ripening than non-stored fruit of similar maturity, but lost water faster than non-stored fruit. Increasing maturity reduced the total amount of water lost during ripening. Cold storage increased the incidence of mesocarp discoloration which became more severe with increasing fruit maturity. Passive water infusion into fruit had no effect on the rate of fruit ripening (and water is obviously not involved as a ‘ripening trigger’) but totally inhibited the manifestation of postharvest browning disorders.     

Intermittent warming of peaches reduces chilling injury by enhancing ethylene production and enzymes mediated by ethylene

SUMMARY

Peaches (Prunus persica ‘Hermoza’) were ripened at 208>C after harvest and either stored at 08C for four weeks (control) to induce chilling injury or given intermittent warming (IW) on the twelfth day of storage (28C for 24.h) to alleviate chilling injury (CI). Continuously stored fruit from control developed wo olliness, a CI disorder, during ripening at 208C after cold storage while only a small percentage of IW fruit developed woolliness. CI fruit produced less ethylene during ripening after storage, and this inhibited ethylene production was closely tied with woolliness development. The IW treatment caused enhanced ethylene production in the fruit when returned to 08C and the ethylene remained higher than control fruit until the end of the storage period. IW also induced the messages for 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) and 1-aminocyclopropane-1-carboxylic acid synthase (ACS) in the ethylene synthesis pathway. IW also elevated the mRNA of the cell wall degrading enzymes polygalacturonase (PG) and endo-1,4-gluconase (EGase). The mRNAs of the cell wall enzymes and the enzymes in the ethylene synthesis pathway remained higher even after 5.d at 08 C following the IW treatment. It is suggested that IW maintained the fruit tissue capacity to ripen normally by preventing inhibition of the ethylene synthesis pathway which occurred in the control fruit after extended storage.     

Changes in ripening behavior of ‘d'Anjou’ pears (Pyrus communis L.) after cold storage

‘d'Anjou’ pear fruit, harvested at optimum maturity with flesh firmness of 6.8 kg, were stored at ?1.1°C. Fruit were ripened at 20°C for 15 days following storage for 1–8 months. Dessert qualities were evaluated organoleptically on Day 10 of each ripening period. Changes in fruit firmness, extractable juice, titratable acids, solubl solids, respiration, ethylene production and internal ethylene were determined daily during each ripening period. Fruit firmness declined continually from 6.8 kg at harvest to 4.5 kg after 8 months of storage. Fruit stored for 2–8 months softened with a similar pattern during a 15-day ripening period at 20°C, while fruit stored for 1 month softened at a slower rate during ripening to 3.2 kg, with a coarse and dry texture after 15 days at 20°C. Fruit stored for 2–4 months ripened with the desirable buttery and juicy texture, while those stored for more than 5 months ripened with a coarse or mealy and dry texture. The buttery and juicy texture was highly correlated with a lower extractable juice, which could be used for quantitative determination of storage life based on ripened fruit quality. Changes in titratable acids and soluble solids during each ripening period were not associated with changes in dessert qualities of the ripened pears. Rates of respiration, ethylene production and internal ethylene during ripening at 20°C varied with duration of storage, but were not associated with changes in dessert qualities of the ripened fruit.     

Leatheriness and mealiness of peaches in relation to fruit maturity and storage temperature

Summary

`Huangjin' peaches (Prunus persica Batsch) were harvested at commercial harvest time (commercial) and 20 d before (early) or after (later) commercial harvest. Fruit from each harvest were stored at three temperature regimes (0, 5 and 10°C) at 95% r.h. After four weeks of storage at 0 or 5°C, early harvested fruit developed more leatheriness but less mealiness and later harvested fruit did not develop leatheriness but developed more mealiness comparedwith fruit from commercial harvest. Overall, fruit stored at 5°C developed more mealiness but less leatheriness than fruitat 0°C for the same period of storage. When stored at 10°C for two weeks, after which fruit were senescent, fruit did not develop any leatheriness or mealiness regardless of harvest times. Fruit with leatheriness were firmer (>30 N) thanjuicy or mealy fruit (<10 N) after the same period of cold storage and 4 d at 20°C. Mealy fruit were as soft as juicy fruit. 1-Aminocyclopropane-1-carboxylate oxidase (ACO) activity, 1-aminocyclopropane-1-carboxylic acid (ACC) content, and polygalacturonase (PG) and galactosidase (GAL) activities were lower, and insoluble pectin content was higher in leathery fruit than that in juicy or mealy fruit. ACO, PG and GAL activity, ACC, and insoluble pectin content were similar between mealy and juicy fruit.     

Physiological factors associated with overripeness,internal breakdown and gel breakdown in plums stored at low temperature

Plums (Prunus salicina cv. Songold) were stored at -0.5°C for up to 50 d. On the day of harvest and thereafter at ten-day intervals, sub-samples were stored at 15°C and allowed to ripen for eight days, with evaluations every two days. Low temperature storage prior to ripening at 15°C was a prerequisite for plums to ripen. Overripeness was inhibited by low- temperature storage but developed when fruit was ripened at, or before, 30 d of storage. Longer storage resulted in the development of gel and internal breakdown at both -0.5°C and during ripening. The transition from overripeness to gel and internal breakdown was associated with significant increases in electrolyte leakage and internal conductivity at a time that viscosities of water soluble pectins were high. The resulting decrease in extrac- table juice suggested that cell fluids which leaked through cell membranes had bound with pectic substances. This was associated with development of gel and internal breakdown.     

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.     

Polyphenoloxidase activity during ripening and chilling stress in ‘Manila’ mangoes

Summary

‘Manila’ mangoes were stored at 6 or 12°C, while a control lot was ripened at 258C. Polyphenoloxidase activity was measured in pulp and peel of mangoes during normal ripening and chilling-stress conditions. Compositional parameters (textural hardness, pH, acidity, and soluble solids) were monitored during ripening and chilling injury (CI) was assessed by visual inspection. PPO activity increased in refrigerated mangoes but fruit stored at 6°C displayed greater activity than those stored at 12°C. Both temperatures produced a peak in enzyme activity at day 16 of storage. Peel browning and acidity correlated with PPO activity (r.=.0.9073 and 0.9818) at 6°C. After the PPO peak was observed at day 16, refrigerated mangoes showed lower enzyme activities; however external browning became more pronounced.     

Effect of storage regimes on pectolytic enzymes,pectic substances,internal conductivity and gel breakdown in cold stored ‘Songold’ plums

Summary

Plums (Prunus salicina cv. Songold) were cold stored according to a single-temperature regime comprising 28 d at ?0.5°C, and a dual-temperature regime comprising 10 d at ?0.5°C followed by 18 d at 7.2°C. After cold storage, the plums were ripened for 8 d at 10°C. Pectolytic enzyme activity, pectic composition, internal conductivity and gel breakdown were determined at seven stages during storage and ripening. Although not exposed to chilling temperatures prior to harvest, approximately 10% of the plums exhibited gel breakdown at harvest, indicating that the disorder cannot be classified solely as a cold-storage chilling disorder. The higher temperatures of the dual-temperature regime resulted in higher polygalacturonase activity than with the single-temperature fruit. Consequently, protopectin degradation and the concomitant production of water- soluble pectins were greater in the dual-temperature fruit. Single-temperature storage resulted in higher pectinmethylesterase activity during the latter stages of storage and during ripening. Increases in temperature after 10 d and 28 d in dual- and single- temperature fruit, respectively, were associated with significant increases in the viscosity of water-soluble pectins, internal conductivity and gel breakdown. The significant positive correlation between internal conductivity and gel breakdown suggested that membrane integrity is closely associated with development of gel breakdown.     

Can Mineral Analysis be Used as a Tool to Predict ‘Braeburn’ Browning Disorders (BBD) in Apple in Commercial Controlled Atmosphere (CA) Storage in Central Europe?

‘Braeburn’ apples stored in controlled atmosphere (CA) frequently present internal flesh browning physiological disorder which is commonly referred as ‘Braeburn’ Browning Disorder (BBD). Apples from different orchards, years or site conditions can vary considerably in their sensitivity. The aim of this research was to evaluate the relationship between the mineral status of ‘Braeburn’ apples before-harvest (18 days) and at early and normal harvest, to correlate the data with the BBD incidence found in apples post storage and to investigate possible reasons for differences in disorder sensitivity. Fruits from seven orchards in the Lake Constance area (South-Western Germany) were harvested at two picking dates and the mineral content was measured before-harvest, at-harvest and during storage. Fruit were stored at 1.5?°C under CA conditions (1 kPa O₂ and 0.5 kPa CO₂) using either a 10 days or a 24 days delayed establishment of CA conditions. Fruit were evaluated after 6 months of storage plus 10 days of shelf life at 18?°C for mineral status and the browning disorder incidence. Results indicate no significant changes of the mineral concentrations in the fruit during CA-storage. Significant correlations between the post storage BBD incidence with K, and in some cases also for the K/Ca ratio and for P at-harvest were found.     

1-MCP对不同成熟度白凤桃冷害发生的影响

以白凤桃果实为材料,研究了1-甲基环丙烯(1-MCP)对低温冷藏条件下果实成熟生理和冷害发生的影响。实验采用25μL/L1-MCP分别对底色转白期(MG)和成熟期(RR)桃果实进行处理,然后置于(0±1)℃冷库中贮藏24d。结果表明,1-MCP处理都能够延缓MG和RR果实的后熟软化进程,降低乙烯释放量,并抑制了果实快速软化阶段的PG酶活性;1-MCP处理提高了贮藏后期MG果实的硬度,降低了出汁率,加剧了冷害的发生程度,1-MCP处理对RR果实的冷害发生率没有显著影响,表明1-MCP对桃冷害的发生程度与果实成熟度有关。     

Effects of polyethylene bags,ethylene absorbent and 1-methylcyclopropene on the storage of Japanese pears

Summary

Storage of the ‘Nijisseiki’ cultivar of Japanese pears was studied over three seasons for periods up to 36 weeks at 0°C. Storage in 50 μm thick low-density polyethylene (LDPE) bags at 0°C considerably delayed yellowing in all experiments, even after fruit was removed to 20°C for 1 week at the end of storage. The addition of an ethylene absorbent made from potassium permanganate on aluminium oxide (Purafil II) further delayed yellowing. Carbon dioxide levels in both treatments varied, but were generally in the range 2–3%. Oxygen levels remained high, generally 16–19%. In bags without Purafil, ethylene levels rose slightly during storage and were generally about 0.15 μl l^–1. When Purafil was included in the bags, the ethylene level was reduced 10-fold or more. A sensory test indicated that the use of LDPE bags and ethylene absorbent resulted in fruit with better eating quality than fruit stored in air. Disorders over the 3-year investigation were low even after long-term storage. The use of polyethylene bags reduced the severity of flesh browning, and flesh spot decay was virtually absent. The use of bags increased the severity of core browning. Inclusion of an ethylene absorbent in bags reduced the severity of disorders, particularly core browning. Treatment of the fruit with 1-methylcyclopropene (1-MCP), before or during storage, resulted in higher ethylene levels in the polyethylene bags. At the concentrations used, 1-MCP did not improve the storage of ‘Nijisseiki’ compared to the use of polyethylene bags with Purafil II.     

Changes in the contents of phenolic substances,phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) accompanying chilling-injury of eggplant fruit

The mechanism of browning, which is a typical chilling-injury of eggplant fruit (Solanum melongena L.), was investigated by determining the changes of phenolic substances, phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) either during storage at 1°C or after exposing fruit to low temperature for various periods.Chlorogenic acid and its isomer, the main substrates for browning, were isolated from eggplants by column and paper chromatography. R_f values and various color reactions of the above acids were compared with those of authentic chlorogenic acid.After 2 days of cold storage at 1°C, when browning was initiated, chlorogenic acid content decreased to less than half that of the initial day, rose to a maximum after 4 days, and then decreased rapidly.PAL activity increased to a peak after 2 days at 1°C, then decreased over 10 days as browning increased. TAL activity also increased after transfer from 1°C to 20°C.It is suggested that rapid turn-over of chlorogenic acid occurs in the early stage of cold storage of eggplant fruit, and development of browning is closely related to chlorogenic acid, PAL and TAL.     

Ca storage and hypobaric storage of white peach ‘Okubo’

White peach ‘Okubo’ fruits were stored for 3 weeks at 1°C in cold storage, controlled atmosphere (CA) storage (3% CO₂ + 3% O₂ and 0% CO₂ + 3% O₂) and hypobaric storage ($\text{1}\text{7}\text{and}\text{6}\text{7}\text{atm}\text{.}$) After removal from storage, fruits were ripened at 20°C. In cold-stored fruits, low temperature injuries (flesh browning, mealy breakdown and abnormal peeling) developed. When O₂ was maintained at 3% without CO₂, the ripening rate after storage was faster than that of fruits which had been held at 20°C directly, and low temperature injuries were not controlled. Under the atmospheric conditions of 3% O₂ and 3% CO₂, ripening rate after storage was not different from that of directly ripened fruits, and injuries were almost completely controlled. In the fruits kept in hypobaric storage of $\text{1}\text{7}\text{atm}\text{.}$, the ripening rate after storage was slower than that of fruits stored in air at 1 atm. (cold storage). Mealy breakdown was reduced, but no effect was found on the flesh browning nor on the abnormal peeling. No significant differences were found between hypobaric-stored fruits of $\text{6}\text{7}\text{atm}\text{.}$ and cold-stored ones.     

The controlled atmosphere storage of Conference pears

Conference pears from five sources in Kent were stored in 0.5%, 1% and 2% O₂ at — 1°C. Samples from one source were also stored in air at the same temperature. On ripening at 18°C in air there was a lag phase before softening commenced. The lag phase generally lasted 3 d for fruit from 0.5% O₂ storage, 2 d for fruit from 1% and 2% O₂ storage, and between 1 and 3 d for fruit from air storage. There was no lag phase before chlorophyll loss. The rate of decline of firmness at 18°C was higher for fruit from 0.5% O₂ storage than for fruit from 1% or 2% O₂ storage. There was no effect of source of fruit on the length of the lag phase or the rate of softening. It was concluded that the storage life of Conference pears at — 1°C was at least 40 weeks in 0.5%, 1% or 2% O₂ and 35 weeks in air.     

Differential propylene induced ethylene production in ‘Anjou’ pears during storage at chilling and non-chilling temperatures

Summary

‘Anjou’ pears were harvested from the Mid-Columbia Experiment Station, Hood River, Oregon, at 67 N firmness, stored at –1° or 20°C for 85 d and periodically tested for sensitivity to 0 or 500 µl l^?1 propylene for at least 14 d at 20°C. Climacteric ethylene of pears stored at 20°C remained at low levels and started rising on the 90th day. Pears chilled at –1°C required 70 d to ripen and produced climacteric ethylene immediately upon transfer to 20°C. The sensitivity of the fruit to exogenous propylene increased progressively with storage time at –1°C. However, the non-chilled fruit responded to propylene similarly to freshly harvested fruit during the first 55 d of storage, then similarly to –1°C-stored fruit up to 85 d. Anjou pear ripening events and the sensitivity of the fruit to exogenous propylene developed differently in storage at non-chilling temperature compared with chilling temperature.     

Effects of controlled atmosphere,edible coating,and 1-methylcyclopropene on improving storage quality of ‘Bartlett’ pears after long-term storage

Recent trends towards greater fresh market use of ‘Bartlett’ pears has increased the need to extend its storage life to prolong the packing and marketing season in the United States Pacific Northwest region. Sixteen and 38%, respectively, of control fruit developed senescence disorders following 5 and 6 months of storage at ?1.1°C. Commercial standard controlled atmosphere (CA) conditions (O₂ at 1.5 kPa and CO₂ < 1 kPa) or edible coating (Semperfresh?, SF) prevent the appearance of senescence disorders for 5 months, but 9% and 16% of fruit, respectively, developed senescence disorders after 6 months. The combination of CA+SF completely inhibited senescence disorders for 6 months. Treatment with CA and SF, alone or in combination, maintained high-storage quality and developed ripening capacity with characteristic melting texture during storage. Senescence disorders were inhibited for 6 months by 0.3 µL l^?1 1-methylcyclopropene (1-MCP), alone or combination with CA or CA+SF. In part these pears developed ripening capacity after 6 months of storage. The combination of CA+SF+1-MCP maintained the highest storage quality with dark green colour and hard firmness, which might be associated and proportional with reductions in ethylene synthesis and respiration rate after long-term storage.     

Chilling induced ethylene biosynthesis in ‘Hayward’ kiwifruit following storage

‘Hayward’ kiwifruit were stored at 0, 5, 10, 15 and 20°C for 5, 12 and 17 days before rewarming to 20°C for 10 more days. Ethylene and CO₂ production, ACC, ACC synthase (ACS) and ACC oxidase (ACO) activities, flesh and core firmness, soluble solids content (SSC) and flesh colour were measured. Kiwifruit stored at 0, 5, 10 and 15°C did not ripen, produce ethylene or show increases in ACS or ACO activity. Fruit stored for 5 days at the above temperatures, then rewarmed to 20°C, did not show any change during the following 10 days. Rewarmed fruit, pre-stored at 0–10°C for 12 days, started autocatalytic ethylene production within 24 h, followed by fruit ripening. Fruit stored at 15°C for 12 days needed 72 h to start ethylene autocatalyse and did not fully ripen during 10 days at 20°C. After 17 days storage at 0–15°C kiwifruit started autocatalytic ethylene production with no delay upon exposure to 20°C. Autocatalytic ethylene production correlated with increased ACC content, and increased activities of ACS and ACO. Fruit held continuously at 20°C started autocatalytic ethylene production after 19 days, with concomitant increases in ACC content, ACS and ACO activities and ripening. Respiration increased after rewarming, concomitantly with the increase in ethylene production.We concluded that exposing kiwifruit to chilling temperatures (0–10°C) for 12 days advanced ethylene biosynthesis and ripening when compared with fruit held continuously at 20°C. The advanced ethylene biosynthesis was due to increase ACS and ACO activities immediately upon rewarming of the fruit.     

Combinations of GA3 and AVG delay fruit maturation,increase fruit size and improve storage life of `Feicheng' peaches

Summary

Different concentrations of aminoethoxyvinylglycine (AVG) and gibberellic acid (GA₃) and their combinations, applied at two stages of fruit growth, were evaluated for prolonging the marketing season of `Feicheng' peaches. GA<sub>3</sub> applied at the end of pit hardening, or AVG applied two weeks before commercial harvest, inhibited fruit maturation on the tree, delayed harvest and reduced flesh browning after cold storage in a concentration-dependent manner. A synergistic effect was found when both GA<sub>3</sub> and AVG were used, with the combination of 100 or 150.mg l<sup>±1</sup> GA<sub>3</sub>, applied at the end of pit hardening, and 100 mg l<sup>±1</sup> AVG, applied two weeks before harvest giving the best results. These combinations retarded the change in ground colour, loss of firmness, and reduction in acidity by 2±3 weeks. Since harvest was prolonged by 2±3 weeks, soluble solids content (SSC) in fruit increased compared with the control (harvested earlier). Fruit size was significantly greater on treated trees compared with the controls when fruit set was controlled to the same level by hand thinning. After four weeks of storage and 4.d at 208C, 83% of control fruit developed tissue browning, but only 5% of AVG + GA<sub>3</sub>-treated fruit developed browning after six weeks of storage and 4 d at 208C. Thus, the marketing season of `Feicheng' peaches was prolonged by at least four weeks by 100 or 150 mg l^±1 of GA₃ and 100 mg l^±1 of AVG. Fruit treated with 150 mg l^±1 GA₃ plus 100 to 150 mg l^±1 AVG showed similar results but failed to ripen properly after cold storage.