Directory UMM :Data Elmu:jurnal:P:Postharvest Biology and Technology:Vol20.Issue3.Nov2000:

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Delaying establishment of controlled atmosphere or CO

exposure reduces ‘Fuji’ apple CO

injury without excessive

fruit quality loss

Luiz Argenta

_{, Xuetong Fan}

_{, James Mattheis}

_*

a_EPAGRI_,_{Estacao Bom Sucesso} _– _C_._P_.₅₉₁_,_CEP_{: 89500}_-₀₀₀_,_Cacador_,_SC_,_Brazil

b_USDA_,_{ARS ERRC}_,₆₀₀_E_._{Mermaid Lane}_,_Wyndmoor_,_PA₁₉₀₃₈_,_USA c_USDA_,_{ARS Tree Fruit Research Laboratory}_,₁₁₀₄_N_. _{Western A}

6enue,Wenatchee,WA98801,USA Received 7 January 2000; accepted 10 June 2000

Abstract

Storage of ‘Fuji’ apple fruit in a high CO2 (3 kPa) and low O2 (1.5 kPa) controlled atmosphere (CA) reduced

firmness and titratable acidity (TA) loss during long term storage. This CA environment also induced development

of internal CO2-injury (brown-heart) and slowed the disappearance of watercore. The symptoms of internal

CO2-injury were first detected 15 days after CA establishment and the severity increased during the first 4 months of

CA-storage. Delaying establishment of CA conditions for 2 – 12 weeks significantly reduced the severity of CO2-injury.

Delaying CO2accumulation to 3 kPa for 1 – 4 months during CA (1.5 kPa O2+0.05 kPa CO2) storage also reduced

development of CO2-injury symptoms. Delaying CA or CO2 accumulation resulted in lower firmness and TA

compared to establishment of CA within 72 h of harvest. However, the delay treatments did result in firmness and TA that were significantly higher compared to values for fruit stored in air. The incidence and severity of senescent injuries (flesh browning and core flush) detected during the late period of storage were greater in air- than CA-stored fruit. The results indicate the susceptibility of ‘Fuji’ apples to CO2-injury is highest during the first weeks of storage

after harvest. Delaying establishment of CA or exposure to elevated CO2after harvest may be a practical strategy to

Elsevier Science B.V.

Keywords:Controlled atmosphere storage; Carbon dioxide injury; Brown-heart

www.elsevier.com/locate/postharvbio

1. Introduction

‘Fuji’ apples are susceptible to the physiological disorders brown-heart, flesh browning, and core flush during cold storage in regular atmosphere (RA) and controlled atmosphere (CA) (Fukuda, 1984). Susceptibility of ‘Fuji’ apples to brown-* Corresponding author. Tel.: +1-509-6642280; fax: +

1-509-6642287.

E-mail address:[email protected] (J. Mattheis).

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L.Argenta et al./Posthar6est Biology and Technology20 (2000) 221 – 229 222

heart CO2-injury as described by Wilkinson and

Fidler (1973) increases with CO2 concentration

(Argenta et al., 1994; Fan et al., 1997), harvest at an advanced maturity (Volz et al., 1998) and fruit size (Park et al., 1997). The risk of CO2-injury also

increases with fruit nitrogen content (Meheriuk et al., 1994), low storage temperature (Smock and Blanpied, 1963) and production under cool tem-perature growing conditions (Lau, 1998). The an-tioxidant diphenylamine (DPA) prevents the development of CO2-injury in apples (Burmeister

and Dilley, 1995; Watkins et al., 1997), however, DPA is not registered for this use. As the use of postharvest chemicals on fresh fruits has received closer scrutiny in recent years, alternative non-chemical procedures for prevention of physiologi-cal disorders such as CO2-injury would be a useful

development in apple storage technology.

Alternative storage protocols may provide a means to reduce the risk of CO2-injury. While

rapid establishment of CA (Sharples and Munoz, 1974; Anderson and Abbott, 1975; Lau et al., 1983) improve post-storage quality of many apple cultivars, delaying establishment of CA or CO2

accumulation during storage reduces the inci-dence of CO2 injury (Bramlage et al., 1977;

Handwerker, 1979; Elgar et al., 1998). The inci-dence of external CO2-injury in ‘Bramley

Seedling’ apples was also reduced when CA es-tablished by fruit respiration and by flushing was delayed for 5 and 20 days, respectively (Colgan et al., 1999). Considering these previous reports, the objectives of the present study were to determine if delayed establishment of CA or CO2

accumula-tion reduce the incidence of CO2 injury while

maintaining acceptable fruit quality of ‘Fuji’ ap-ples.

2. Materials and methods

‘Fuji’ apples (MalusX domestica Borkh.) were harvested 173 and 177 days after full bloom in 1997 and 1998, respectively, from a commercial orchard in Orondo, WA. The fruit were placed into 0.145 m3 _{stainless steel chambers and cooled}

to 0.5°C within 36 h of harvest. Fruit were stored at 0.5°C in RA, or in CA at 1.5 kPa O2+0.05

kPa CO2or 1.5 kPa O2+3 kPa CO2under static

conditions. Establishment of CA conditions was initiated 36 h after harvest and atmospheres were established within 72 h of harvest (rapid CA). Chamber O2 and CO2 concentrations were

moni-tored and corrected automatically (Techni-Sys-tems) at 90 min intervals. Atmospheres were established and maintained using compressed air and CO2 plus N2 from a membrane generator

system (Permea). Hydrated lime [Ca(OH2)] (0.1

kg per kg fruit) was placed in chambers to help maintain the CO2 concentration at 0.05 kPa. For

the CA delay treatments, fruit were held in RA at 0.5°C for 2 – 12 weeks after harvest, and then CA (1.5 kPa O2+3 kPa CO2) was established and

maintained for the remainder of the 8 month storage period. For the CO2 delay treatments,

fruit were stored in 1.5 kPa O2+0.05 kPa CO2

Fig. 1. Internal ethylene concentration (IEC) and CO2 produc-tion by ‘Fuji’ apples harvested in 1997 and stored at 0.5°C in air or controlled atmosphere with 1.5 kPa O2+3 kPa CO2or 1.5 kPa O2+0.05 kPa CO2. Values are means of 18 fruit (IEC) or three replicate 1 kg samples (CO2production). Verti-cal bar indicates LSD0.05for significant treatment×days inter-action.

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Fig. 2. Firmness and titratable acidity of ‘Fuji’ apples harvested in 1997 and 1998 and stored at 0.5°C in air or controlled atmosphere with 1.5 kPa O2+3 kPa CO2or 1.5 kPa O2+0.05 kPa CO2. Values are means of 18 fruit. Vertical bar indicates LSD0.05 for significant treatment×days interaction.

for 1, 2, 3 or 4 months after harvest, then CO2

was increased to 3 kPa for the remainder of the 8 month storage period.

Maturity and quality were determined for indi-vidual fruit at harvest and after storage by analy-ses of fruit respiration rate, internal ethylene concentration (IEC), flesh firmness, soluble solids content (SSC) and titratable acidity (TA). There were three replicate 1 kg samples for respiration analysis, all other analyses used 18 individual fruit. For respiration analyses, fruit were placed into 20 l chambers at 20°C supplied with com-pressed, ethylene-free air flowing at 100 ml min−1

. Effluent air was analyzed for CO2using a

gas chromatograph (Hewlett Packard 5890) equipped with a methanizer (John T. Booker), flame ionization detector and a 0.6 m, 2 mm i.d. stainless steel column packed with 80 – 100 mesh Poropak Q (Supelco). Oven, detector, methanizer and injection temperatures were 50, 200, 290 and 150°C, respectively. Gas flows for N2, H2 and air

were 70, 30 and 300 ml min−1_{, respectively.}

Inter-nal ethylene concentrations of individual fruit were measured on gas samples removed from the

fruit core (Williams and Patterson, 1962) using a gas chromatograph (Hewlett Packard 5880A) equipped with a flame ionization detector and a 0.5 m, 3.2 mm i.d., glass column packed with 80 – 100 mesh Poropak Q. Oven, detector, and injection temperatures were 90, 200 and 100°C, respectively. N2, H2, and air flows were 25, 25,

and 300 ml min−1_{, respectively. Flesh firmness}

was measured on two pared surfaces per fruit using a penetrometer with an 11 mm tip (Lake City Technical). Determination of SSC and TA used juice freshly prepared with a Champion juicer (Plastaket Mfg.). A refractometer (Atago) was used to measure SSC and TA was determined by titrating 10 ml of juice with 0.1 M KOH to pH 8.2 using an autotitrator (Radiometer).

Severity of watercore, CO2-injury (wet, well

defined, dark brown cortex and pith), flesh browning (light, diffuse, brown in the cortex), and core flush (light, diffuse, brown into the core, pith), were evaluated visually by cutting the fruit in half through the equator. The watercore sever-ity was scored using a scale from 1, no watercore to 4, very severe watercore. The severity of CO2

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-L.Argenta et al./Posthar6est Biology and Technology20 (2000) 221 – 229 224

Fig. 3. Watercore (A) and development of CO2-injury (B) in ‘Fuji’ apples. (A) Apples were stored at 0.5°C in air, 1.5 kPa O2+3 kPa CO2 or 1.5 kPa O2+0.05 kPa CO2. (B) Apples stored in 1.5 kPa O2+3 kPa CO2. Pooled data from 1997 and 1998 seasons is presented. Both watercore and brown-heart were scored using a scale from 1 (none) to 4 (severe). Incidence of cavities was rated as 1 (none) or 2 (present). Vertical bar indicates LSD0.05for significant treatment×days interaction.

injury was scored as: (1) none; (2) 1 – 30% of flesh (cortex and pith) dark brown; (3) 31 – 60% of flesh dark brown; and (4) 61 – 100% of flesh dark brown. Incidence of cavities was rated as absent (1) or present (2). Flesh browning and core flush were assessed as: absent (1), slight (2) and severe (3).

Data were analyzed using SAS ver 6.12 (SAS Institute, 1992). Treatment effects were analyzed by the ANOVA procedure and treatment mean separation was determined using Fisher’s pro-tected LSD or Duncan’s multiple range tests (PB

0.05).

3. Results and discussion

3.1. Physiological and quality changes during storage

Increased internal ethylene concentration (IEC) in RA-stored fruit was initially detected after 1 month storage (Fig. 1). IEC and respiration rates remained low in CA-stored fruit similar to previ-ous reports (Fan, 1992; Jobling and McGlasson, 1995). Fruit stored in CA with 1.5 kPa O2 and 3

kPa CO2 for 8 months had lower IEC but similar

respiration rate compared with fruit stored in CA with 1.5 kPa O2+0.05 kPa CO2.

Firmness and TA of CA and RA fruit were similar after 2 months (1997) and 4 months (1998) storage (Fig. 2). After 6 and 8 months storage, firmness and TA were higher in CA- compared to RA-stored fruit. High (3 kPa) CO2 was more

effective than low (0.05 kPa) CO2 in maintaining

firmness and TA during long-term storage. Short-term CA storage may have minor beneficial ef-fects on maintenance of firmness and acidity of ‘Fuji’ apples (Drake, 1993), but high CO2 is

re-quired to maintain quality during long-term stor-age. Relatively high CO2 concentrations retard

softening and acidity loss during low O2 CA

storage of most apple cultivars (Fidler, 1973). In both seasons, dissipation of watercore was slower in CA- than in RA-stored fruit while symptoms of internal CO2-injury (brown-heart)

were first observed after 15 days of CA storage (Fig. 3). The severity of CO2-injury increased

Fig. 4. Flesh browning (FB) and core flush (CF) incidence in ‘Fuji’ apples stored at 0.5°C in air (RA) or controlled atmo-sphere with 1.5 kPa O2+0.05 kPa CO2(CA) during 1997 and 1998 seasons. Both flesh browning and core flush were as-sessed as: none (1) slight (2) or severe (3).

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Fig. 5. Severity of CO2-injury in ‘Fuji’ apples harvested in 1997 and 1998. Apples were stored for 8 months at 0.5°C in air or in controlled atmosphere (CA). Rapid CA: Fruit cooled within 36 h of harvest and CA established within 72 h of harvest. CA delay: Fruit held at 0.5°C in air for 2 – 12 weeks then moved to CA with 1.5 kPa O2+3 kPa CO2. CO2delay: Fruit cooled to 0.5°C within 36 h of harvest and CA established within 72 h of harvest. Fruits held in CA with 1.5 kPa O2+0.05 CO2kPa for 1 – 4 months then moved to CA with 1.5 kPa O2+3 kPa CO2. Severity of CO2-injury was rated as 1 (none) to 4 (severe). Values are means of 18 fruit per treatment. Bars with the same letter are not significantly different (Duncan’s Multiple Range Test,PB_0.05).

during the first 4 months of storage then remained constant for the remainder of the storage period. Cavities in cortical tissue were detected after 6 months storage. The symptoms of CO2-injury

(wet, dark browning in fruit mesocarp) may give rise to typical cork-like cavities as desiccation of damaged tissue occurs during storage (Wilkinson and Fidler, 1973).

Core flush and flesh browning were detected after 4 (1997) and 6 (1998) months storage (Fig. 4). Core flush did not occur in CA-stored fruit

while flesh browning occurred in RA- and CA-(1.5 kPa O2+0.05 kPa CO2) stored fruit in both

seasons. Core flush is a symptom of senescence that may be intensified by low temperature stor-age and is characterized by yellowish-brown dis-coloration of the apple core area (Wilkinson and Fidler, 1973). In RA-stored fruits, the flesh browning resembled senescent breakdown (Wilkinson and Fidler, 1973; Meheriuk et al., 1994) because the diffuse, light browning ap-peared more on the outer portion of the cortex

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L.Argenta et al./Posthar6est Biology and Technology20 (2000) 221 – 229 226

tissue and was often associated with browning of vascular tissue. In CA- (1.5 kPa O2+0.05 kPa

CO2) stored fruit, the symptoms of flesh browning

(diffuse, light browning in the fruit flesh) were similar to that described for ‘Delicious’ apples (Meheriuk et al., 1994). Flesh browning resembles senescent breakdown in appearance and is more predominant in fruits with severe watercore, fruit harvested over-mature, large fruit, fruit grown in

locations with cool temperatures and in some cases in CA-stored fruit (Meheriuk et al., 1994). 3.2. Effects of delayed CA or CO2

Delaying CA establishment (1.5 kPa O2+3

kPa CO2) for 2 – 12 weeks resulted in a significant

reduction in the severity of CO2-injury (Fig. 5).

Fruit harvested during 1998 required a longer

Fig. 6. Severity of watercore and flesh browning in ‘Fuji’ apples harvested in 1998. Apples were stored for 8 months at 0.5°C in air or in controlled atmosphere (CA). Rapid CA: Fruit cooled within 36 h of harvest and CA established within 72 h of harvest. CA delay: Fruit held at 0.5°C in air for 2 – 12 weeks then moved to CA with 1.5 kPa O2+3 kPa CO2. CO2delay: Fruit cooled to 0.5°C within 36 h of harvest and CA established within 72 h of harvest. Fruits held in CA with 1.5 kPa O2, 0.05 kPa for 1 – 4 months then moved to CA with 1.5 kPa O2+3 kPa CO2. Severity of these injuries was scored as 1 (none) to 3 (severe) for flesh browning, 4 (severe) for watercore. Values are means of 18 fruit per treatment. Bars with the same letter are not significantly different (Duncan’s Multiple Range Test,PB0.05).

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Fig. 7. Firmness and titratable acidity in ‘Fuji’ apples harvested in 1998. Apples were stored for 8 months at 0.5°C in air or in controlled atmosphere (CA). Rapid CA: Fruit cooled within 36 h of harvest and CA established within 72 h of harvest. CA delay: Fruit held at 0.5°C in air for 2 – 12 weeks then moved to CA with 1.5 kPa O2+3 kPa CO2. CO2delay: Fruit cooled within 36 h of harvest and CA established within 72 h of harvest. Fruits were stored in CA with 1.5 kPa O2+0.05 kPa for 1 – 4 months then moved to CA with 1.5 kPa O2+3 kPa CO2. Values are means of 18 fruit per treatment. Bars with the same letter are not significantly different (Duncan’s Multiple Range Test,PB0.05).

delay to reduce injury severity than fruit harvested during 1997. Delaying CO2 (3 kPa) accumulation

for 1 – 4 months during CA (1.5 kPa O2+0.05

kPa CO2) storage also reduced the development

of CO2-injury symptoms in both seasons. Delayed

CA or CO2 accumulation allowed greater

disap-pearance of watercore during storage compared to rapid CA (Fig. 6). There was development of mild flesh browning (average rating 1.5) during the 1997 season, but there were no treatment

differ-ences (data not presented). The severity of flesh browning during the 1998 season was highest in RA-stored fruit and in fruit subjected to the longest CO2delay (Fig. 6). Fruit stored in CA (1.5

kPa O2+3 kPa CO2) delayed for 2 – 8 weeks did

not develop flesh browning. Firmness and acidity loss during eight months of storage increased with delayed establishment of CA or CO2

accumula-tion (Fig. 7). Delayed CA or CO2 accumulation

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L.Argenta et al./Posthar6est Biology and Technology20 (2000) 221 – 229 228

2.3 – 6 N, during 1997 and 1998, respectively) and TA (8 – 13% and 6 – 20%, during 1997 and 1998, respectively) compared to fruit stored in CA with 3 kPa CO2 established immediately after harvest.

However, delaying CA or CO2 resulted in higher

firmness and TA compared to fruit stored in CA with 0.05 kPa CO2 established immediately. After

8 months of storage, the firmness and TA of fruit stored after CA or CO2delay were approximately

the same of those fruit stored in CA with 1 kPa CO2

established immediately (data not presented). Rapid cooling (Smock and Blanpied, 1963) and rapid establishment of CA conditions (Sharples and Munoz, 1974; Anderson and Abbott, 1975; Olsen, 1980; Little and Peggie, 1987) are important for maintenance of fruit quality for many apple cultivars. However, delaying CO2 accumulation

can reduce the incidence of CO2injury in

suscepti-ble cultivars (Bramlage et al., 1977; Handwerker, 1979; Watkins et al., 1997; Elgar et al., 1998; Colgan et al., 1999). Most of the CO2-injury in

‘Fuji’ apples developed during the first month of storage (Fig. 3) and 2 – 6 weeks of CA delay or 4 weeks of CO2delay significantly reduce the severity

of CO2-injury (Fig. 5). These results confirm

previ-ous studies with ‘Bramley Seedling’ (Colgan et al., 1999) and ‘Braeburn’ apples (Elgar et al., 1998) where incidence and severity of CO2disorders were

decreased by storing fruit in air at 0°C for 2 – 3 weeks prior to establishment of CA conditions. While delaying CA or CO2 accumulation reduces

development of CO2induced disorders, the delays

may increase the chance that development of senes-cent diffuse flesh browning in ‘Fuji’ (Fig. 6) and coreflush in ‘Braeburn’ apples (Elgar et al., 1998) will occur.

The results of the present study indicate that susceptibility of ‘Fuji’ apples to CO2-injury is

highest during the first weeks of storage after harvest, and that delaying CA or CO2

accumula-tion in the storage environment reduces the inci-dence of CO2-injury. The delay can result in

increased loss of firmness and TA, however, the additional quality loss is not sufficient to negate the benefits of CA compared to fruit stored in RA. Delaying establishment of CA or CO2after harvest

may be a practical strategy to reduce CO2-injury,

but the delay should be as short as possible to

preserve the beneficial effects of CA on fruit quality and control of other physiological disorders such as flesh browning. The period of CA or CO2-delay

required may vary between seasons (Fig. 5). As the susceptibility of apples to CO2 injury varies

be-tween seasons and orchards (Elgar et al., 1998; Lau, 1998) a reliable method to segregate fruit by susceptibility to CO2injury would allow

determina-tion of the period of CA or CO2 delay necessary

for each lot of fruits. ‘Fuji’ apples are more tolerant to high CO2 during the later storage period

(Ar-genta, unpublished data), therefore new strategies for ‘Fuji’ CA storage may reduce CO2-injury

dur-ing early period of storage and also reduce energy costs of CO2 removal during the later storage

period.

References

Anderson, R.E., Abbott, J.A., 1975. Apple quality after stor-age in air, delayed CA or CA. HortScience 10, 255 – 257. Argenta, L.C., Brackmann, A., Mondardo, M., 1994.

Quali-dade po´s-colheita de mac¸a˜s armazenadas sob diferentes temperaturas e concentrac¸o˜es de CO2 e O2. Rev. Bras. Fisiol. Veg. 6, 121 – 126.

Bramlage, W.J., Bareford, P.H., Blanpied, G.D. et al., 1977. Carbon dioxide treatments for ‘McIntosh’ apples before CA storage. J. Am. Soc. Hort. Sci. 102, 658 – 662. Burmeister, D.M., Dilley, D.R., 1995. A ‘scald-like’ controlled

atmosphere disorder of Empire apples — a chilling injury induced by CO2. Postharvest Biol. Technol. 6, 1 – 7. Colgan, R.J., Dover, C.J., Johnson, D.S., Pearson, K., 1999.

Delay CA and oxygen at 1 kPa or less control superficial scald without CO2 injury on Bramley’s Seedling apples. Postharvest Biol. Technol. 16, 223 – 231.

Drake, S.R., 1993. Short-term controlled atmosphere storage improved quality of several apple cultivars. J. Am. Soc. Hort. Sci. 118, 486 – 489.

Elgar, H.J., Burmeister, D.M., Watkins, C.B., 1998. Storage and handling effects on a CO2-related internal browning disorder of ‘Braeburn’ apple. HortScience. 33, 719 – 722. Fan, X., 1992. Maturity and storage of ‘Fuji’ apples.

Washing-ton State University, Pullman. MS Thesis, 203 pp. Fan, X., Mattheis, J.P., Patterson, M.E., Fellman, J.K., 1997.

Evaluation of ‘Fuji apple ground color at harvest as a predictor of post-storage fruit quality. In: E.J. Mitcham (Ed.), Apples and Pears. Proceedings of 7th International Controlled Atmosphere Conference 2, 235 – 240.

Fidler, J.C., 1973. Conditions of storage. In: Fidler, J.C., Wilkinson, B.G., Edney, K.L., Sharples, R.O (Eds.), The Biology of Apples and Pear Storage. Commonwealth Bu-reau of Horticulture and Plantation Crops, East Malling, UK, pp. 3 – 61.

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Fukuda, H., 1984. Relationship of watercore and calcium to the incidence of internal storage disorders of ‘Fuji’ apple fruit. J. Jpn. Soc. Hort. Sci. 53, 298 – 302.

Handwerker, T.S., 1979. The effect of high CO2treatments at storage temperatures on the level of organic acids and phenolic compounds and the incidence of CO2 injury in apples. Cornell University, Ithaca. Ph.D. Thesis, 70 pp. Jobling, J.J., McGlasson, W.B., 1995. A comparison of ethylene

production, maturity and controlled atmosphere storage life of ‘Gala’, ‘Fuji’ and ‘Lady Williams’ apples (Malus domes

-tica, Borkh.). Postharvest Biol. Technol. 6, 209 – 218. Lau, O.L., Meheriuk, M., Olsen, K.L., 1983. Effects of ‘rapid

CA’, high CO2, and CaCl2treatment on storage behavior of ‘Golden Delicious’ apples. J. Am. Soc. Hort. Sci. 108, 230 – 233.

Lau, O.L., 1998. Effect of growing season, harvest maturity, waxing, low O2and elevated CO2on flesh browning disorders in ‘Braeburn’ apples. Postharvest Biol. Technol. 14, 131 – 141. Little, C.R., Peggie, I.D., 1987. Storage injury of pome fruit caused by stress levels of oxygen, carbon dioxide, tempera-ture, and ethylene. HortScience 22, 783 – 790.

Meheriuk, M., Prange, R.K. Lidster, P.D., Porritt, S.W., 1994. Postharvest disorders of apples and pears. Agriculture Canada Publication 1737E. Communications Branch, Agri-culture Canada Ottawa, Ont. 66 p.

Park, Y., Kweon, H.J., Kim, H.Y., Ryu, O.H., 1997. Preharvest factors affecting the incidence of physiological disorders

during CA storage of ‘Fuji’ apples. J. Korean Soc. Hort. Sci. 38, 725 – 729.

SAS Institute, Inc. Doing more with SAS/ASSIST software. Version 6. SAS Institute, Inc., 1992. Cary, NC, 368 p. Sharples, R.O., Munoz, G.C., 1974. The effects of delays in the

period taken to cool and establish low O2conditions on the quality of stored Cox’s Orange Pippin apples. J. Hort. Sci. 49, 277 – 286.

Smock, R.M., Blanpied, G.D., 1963. Some effects of tempera-ture and rate of oxygen reduction on the quality of con-trolled atmosphere stored ‘McIntosh’ apples. Proc. Am. Soc. Hort. Sci. 83, 135 – 138.

Volz, R.K., Biasi, W.V., Grant, J.A., Mitcham, E.J., 1998. Prediction of controlled atmosphere-induced flesh browning in ‘Fuji’ apple. Postharvest Biol. Technol. 13, 97 – 107. Watkins, C.B., Silsby, K.J., Goffinet, M.C., 1997. Controlled

atmosphere and antioxidant effects on external CO2injury of ‘Empire’ apples. HortScience 32, 1242 – 1246.

Wilkinson, B.G., Fidler, J.C., 1973. Physiological disorders. In: Fidler, J.C., Wilkinson, B.G., Edney, K.L., Sharples, R.O (Eds.), The Biology of Apples and Pear Storage. Common-wealth Bureau of Horticulture and Plantation Crops, East Malling, UK, pp. 65 – 131.

Williams, M.W., Patterson, M.E, 1962. Internal atmospheres in Bartlett pears stored in controlled atmospheres. Proc. Am. Soc. Hort. Sci. 80, 129 – 136.

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L.Argenta et al./Posthar6est Biology and Technology20 (2000) 221 – 229 224

Fig. 3. Watercore (A) and development of CO2-injury (B) in

‘Fuji’ apples. (A) Apples were stored at 0.5°C in air, 1.5 kPa O2+3 kPa CO2 or 1.5 kPa O2+0.05 kPa CO2. (B) Apples

stored in 1.5 kPa O2+3 kPa CO2. Pooled data from 1997 and

1998 seasons is presented. Both watercore and brown-heart were scored using a scale from 1 (none) to 4 (severe). Incidence of cavities was rated as 1 (none) or 2 (present). Vertical bar indicates LSD0.05for significant treatment×days interaction.

injury was scored as: (1) none; (2) 1 – 30% of flesh

(cortex and pith) dark brown; (3) 31 – 60% of flesh

dark brown; and (4) 61 – 100% of flesh dark

brown. Incidence of cavities was rated as absent

(1) or present (2). Flesh browning and core flush

were assessed as: absent (1), slight (2) and severe

(3).

Data were analyzed using SAS ver 6.12 (SAS

Institute, 1992). Treatment effects were analyzed

by the ANOVA procedure and treatment mean

separation was determined using Fisher’s

pro-tected LSD or Duncan’s multiple range tests (

P

B

0.05).

3. Results and discussion

3.1. Physiological and quality changes during

storage

Increased internal ethylene concentration (IEC)

in RA-stored fruit was initially detected after 1

month storage (Fig. 1). IEC and respiration rates

remained low in CA-stored fruit similar to

previ-ous reports (Fan, 1992; Jobling and McGlasson,

1995). Fruit stored in CA with 1.5 kPa O

and 3

kPa CO

for 8 months had lower IEC but similar

respiration rate compared with fruit stored in CA

with 1.5 kPa O

+

0.05 kPa CO

.

Firmness and TA of CA and RA fruit were

similar after 2 months (1997) and 4 months (1998)

storage (Fig. 2). After 6 and 8 months storage,

firmness and TA were higher in CA- compared to

RA-stored fruit. High (3 kPa) CO

was more

effective than low (0.05 kPa) CO

in maintaining

firmness and TA during long-term storage.

Short-term CA storage may have minor beneficial

ef-fects on maintenance of firmness and acidity of

‘Fuji’ apples (Drake, 1993), but high CO

is

re-quired to maintain quality during long-term

stor-age. Relatively high CO

concentrations retard

softening and acidity loss during low O

CA

storage of most apple cultivars (Fidler, 1973).

In both seasons, dissipation of watercore was

slower in CA- than in RA-stored fruit while

symptoms of internal CO

-injury (brown-heart)

were first observed after 15 days of CA storage

(Fig. 3). The severity of CO

-injury increased

Fig. 4. Flesh browning (FB) and core flush (CF) incidence in

‘Fuji’ apples stored at 0.5°C in air (RA) or controlled atmo-sphere with 1.5 kPa O2+0.05 kPa CO2(CA) during 1997 and

1998 seasons. Both flesh browning and core flush were as-sessed as: none (1) slight (2) or severe (3).

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Fig. 5. Severity of CO2-injury in ‘Fuji’ apples harvested in 1997 and 1998. Apples were stored for 8 months at 0.5°C in air or in

controlled atmosphere (CA). Rapid CA: Fruit cooled within 36 h of harvest and CA established within 72 h of harvest. CA delay: Fruit held at 0.5°C in air for 2 – 12 weeks then moved to CA with 1.5 kPa O2+3 kPa CO2. CO2delay: Fruit cooled to 0.5°C within

36 h of harvest and CA established within 72 h of harvest. Fruits held in CA with 1.5 kPa O2+0.05 CO2kPa for 1 – 4 months then

moved to CA with 1.5 kPa O2+3 kPa CO2. Severity of CO2-injury was rated as 1 (none) to 4 (severe). Values are means of 18 fruit

per treatment. Bars with the same letter are not significantly different (Duncan’s Multiple Range Test,PB_0.05).

during the first 4 months of storage then remained

constant for the remainder of the storage period.

Cavities in cortical tissue were detected after 6

months storage. The symptoms of CO

-injury

(wet, dark browning in fruit mesocarp) may give

rise to typical cork-like cavities as desiccation of

damaged tissue occurs during storage (Wilkinson

and Fidler, 1973).

Core flush and flesh browning were detected

after 4 (1997) and 6 (1998) months storage (Fig.

4). Core flush did not occur in CA-stored fruit

while flesh browning occurred in RA- and

CA-(1.5 kPa O

+

0.05 kPa CO

) stored fruit in both

seasons. Core flush is a symptom of senescence

that may be intensified by low temperature

stor-age and is characterized by yellowish-brown

dis-coloration of the apple core area (Wilkinson and

Fidler, 1973). In RA-stored fruits, the flesh

browning

resembled

senescent

breakdown

(Wilkinson and Fidler, 1973; Meheriuk et al.,

1994) because the diffuse, light browning

ap-peared more on the outer portion of the cortex

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L.Argenta et al./Posthar6est Biology and Technology20 (2000) 221 – 229 226

tissue and was often associated with browning of

vascular tissue. In CA- (1.5 kPa O

+

0.05 kPa

CO

) stored fruit, the symptoms of flesh browning

(diffuse, light browning in the fruit flesh) were

similar to that described for ‘Delicious’ apples

(Meheriuk et al., 1994). Flesh browning resembles

senescent breakdown in appearance and is more

predominant in fruits with severe watercore, fruit

harvested over-mature, large fruit, fruit grown in

locations with cool temperatures and in some

cases in CA-stored fruit (Meheriuk et al., 1994).

3.2. Effects of delayed CA or CO

Delaying CA establishment (1.5 kPa O

+

3 kPa CO

) for 2 – 12 weeks resulted in a significant

reduction in the severity of CO

-injury (Fig. 5).

Fruit harvested during 1998 required a longer

within 36 h of harvest and CA established within 72 h of harvest. Fruits held in CA with 1.5 kPa O2, 0.05 kPa for 1 – 4 months then

moved to CA with 1.5 kPa O2+3 kPa CO2. Severity of these injuries was scored as 1 (none) to 3 (severe) for flesh browning, 4

(severe) for watercore. Values are means of 18 fruit per treatment. Bars with the same letter are not significantly different (Duncan’s Multiple Range Test,PB0.05).

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of harvest and CA established within 72 h of harvest. Fruits were stored in CA with 1.5 kPa O2+0.05 kPa for 1 – 4 months then

moved to CA with 1.5 kPa O2+3 kPa CO2. Values are means of 18 fruit per treatment. Bars with the same letter are not

significantly different (Duncan’s Multiple Range Test,PB0.05).

delay to reduce injury severity than fruit harvested

during 1997. Delaying CO

(3 kPa) accumulation

for 1 – 4 months during CA (1.5 kPa O

+

0.05 kPa CO

) storage also reduced the development

of CO

-injury symptoms in both seasons. Delayed

CA or CO

accumulation allowed greater

disap-pearance of watercore during storage compared to

rapid CA (Fig. 6). There was development of mild

flesh browning (average rating 1.5) during the

1997 season, but there were no treatment

differ-ences (data not presented). The severity of flesh

browning during the 1998 season was highest in

RA-stored fruit and in fruit subjected to the

longest CO

delay (Fig. 6). Fruit stored in CA (1.5

kPa O

+

3 kPa CO

) delayed for 2 – 8 weeks did

not develop flesh browning. Firmness and acidity

loss during eight months of storage increased with

delayed establishment of CA or CO

accumula-tion (Fig. 7). Delayed CA or CO

accumulation

resulted in increased loss of firmness (5 – 8 N and

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L.Argenta et al./Posthar6est Biology and Technology20 (2000) 221 – 229 228

2.3 – 6 N, during 1997 and 1998, respectively) and

TA (8 – 13% and 6 – 20%, during 1997 and 1998,

respectively) compared to fruit stored in CA with

3 kPa CO

established immediately after harvest.

However, delaying CA or CO

resulted in higher

firmness and TA compared to fruit stored in CA

with 0.05 kPa CO

established immediately. After

8 months of storage, the firmness and TA of fruit

stored after CA or CO

delay were approximately

the same of those fruit stored in CA with 1 kPa CO

established immediately (data not presented).

Rapid cooling (Smock and Blanpied, 1963) and

rapid establishment of CA conditions (Sharples

and Munoz, 1974; Anderson and Abbott, 1975;

Olsen, 1980; Little and Peggie, 1987) are important

for maintenance of fruit quality for many apple

cultivars. However, delaying CO

accumulation

can reduce the incidence of CO

injury in

suscepti-ble cultivars (Bramlage et al., 1977; Handwerker,

1979; Watkins et al., 1997; Elgar et al., 1998;

Colgan et al., 1999). Most of the CO

-injury in

‘Fuji’ apples developed during the first month of

storage (Fig. 3) and 2 – 6 weeks of CA delay or 4

weeks of CO

delay significantly reduce the severity

of CO

-injury (Fig. 5). These results confirm

previ-ous studies with ‘Bramley Seedling’ (Colgan et al.,

1999) and ‘Braeburn’ apples (Elgar et al., 1998)

where incidence and severity of CO

disorders were

decreased by storing fruit in air at 0°C for 2 – 3

weeks prior to establishment of CA conditions.

While delaying CA or CO

accumulation reduces

development of CO

induced disorders, the delays

may increase the chance that development of

senes-cent diffuse flesh browning in ‘Fuji’ (Fig. 6) and

coreflush in ‘Braeburn’ apples (Elgar et al., 1998)

will occur.

The results of the present study indicate that

susceptibility of ‘Fuji’ apples to CO

-injury is

highest during the first weeks of storage after

harvest, and that delaying CA or CO

accumula-tion in the storage environment reduces the

inci-dence of CO

-injury. The delay can result in

increased loss of firmness and TA, however, the

additional quality loss is not sufficient to negate the

benefits of CA compared to fruit stored in RA.

Delaying establishment of CA or CO

after harvest

may be a practical strategy to reduce CO

-injury,

but the delay should be as short as possible to

preserve the beneficial effects of CA on fruit quality

and control of other physiological disorders such

as flesh browning. The period of CA or CO

-delay

required may vary between seasons (Fig. 5). As the

susceptibility of apples to CO

injury varies

be-tween seasons and orchards (Elgar et al., 1998; Lau,

1998) a reliable method to segregate fruit by

susceptibility to CO

injury would allow

determina-tion of the period of CA or CO

delay necessary

for each lot of fruits. ‘Fuji’ apples are more tolerant

to high CO

during the later storage period

(Ar-genta, unpublished data), therefore new strategies

for ‘Fuji’ CA storage may reduce CO

-injury

dur-ing early period of storage and also reduce energy

costs of CO

removal during the later storage

period.

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