PHYSIOLOGICAL AND BIOCHEMICAL RESPONSES OF FRUITS TO CONTROLLED ATMOSPHERES

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
503	1199	1020	100%

Progress 10/01/00 to 09/30/05

Outputs
During the past five years, my associates and I were able to further explore the physiological and biochemical bases of reduced oxygen and/or elevated carbon dioxide atmospheres on several fruits, including apples, cherries, grapes, pomegranates, strawberries, and fresh-cut fruit products. We determined the optimal atmospheric composition for these fruits and this information is currently being used on a commercial scale. We identified the critical levels below which (oxygen) and/or above which (carbon dioxide) respiratory metabolism is altered and fermentative metabolites are formed resulting in off-flavors. This information is being used by those who are testing various surface coatings and polymeric films for commercial use. Continued improvements in polymeric films and other packaging materials will facilitate expanded use of MA packaging to extend postharvest-life of fresh-cut fruits and permit their distribution via vending machines and quick-service resturants. MAP is an effective way to maintain the desired atmospheric composition between shipping point and the consumers home. When evaluating polymeric films, it is important to place the control product in perforated plastic bags to separate the effect of the film on reducing water loss from its effect as a barrier to carbon dioxide and oxygen diffusion. Although much research has been done on the use of surface coatings to modify the atmosphere within many commodities, this technology has not been used to any extent because of the variability in composition among batches of the coating material. When combined with the natural variation in the gas diffusion characteristics among individual commodity units, a portion of each lot is lost due to off-flavors caused by fermentative metabolites. Further research is needed to overcome these constraints to use of surface coatings for modification of internal atmospheres of fruits. More cost-effective methods for establishing and maintaining MAs will facilitate their use during storage at shipping points, transportation, and storage at destination points. Maintaining the MA chain is the second most important factor after the cold chain in keeping quality and safety of fresh produce between harvest and consumption. Further evaluations are needed of the synergistic effects of MA and the ethylene-action-inhibitor,1-methylcyclopropene, on delaying ripening of partially-ripe climacteric fruits and deterioration (browning and softening) of fresh-cut fruit products

Impacts
Research conducted under this project resulted in specific recommendations for optimal modified atmospheres for several fruits, including bananas, cherries, grapes, mandarins, pomegranates, and strawberries. These recommendations are being followed by the fruit shippers and transportation companies.

Publications

none 2005

Progress 01/01/04 to 12/31/04

Outputs
Superficial scald incidence and severity were greater in the pomegranates harvested on November 18 than in those harvested on October 20, 2003, indicating that this disorder may e associated with sensescence. All pomegranates from the 11/18 and 10/20 harvests that were kept in air exhibited some superficial scald after 4 and 6 months, respectively. Neither the diphenylamine (DPA) nor 1-methylcyclo-propene (1-MCP) alone or together reduced scald incidence and severity. In contrast, the 3 CA storage conditions significantly reduced scald incidence and severity on pomegranates from both harvest dates for up to 6 months at 7 C. However, the two CA with 1% 02 resulted in greater accumulation of fermentative volatiles (acetaldehyde, ethanol, and ethyl acetate) than the CA with 5% 02, especially in the October 20th harvested pomegranates. In addition to the fungistatic effects of 15% CO2, it appears to be critical to inhibition of scald development on pomegranates. These results confirm our recommendation of 5% O2 + 15% CO2 as the optimal CA for pomegranates at 7 C and 90-95% relative humidity. It appears that the biochemical basis of superficial scald in pomegranates is different from that in apples. No alpha-farnesene or its conjugates were found in the peel of pomegranates. We are examining the possible involvement of fatty acids oxidation in the development of superficial scald on pomegranate skin.

Impacts
We identified 5% oxygen + 15% carbon dioxide as the optimal controlled atmosphere storage conditions form pomegranates kept at 7 C and 90 to 95% relative humidity for up to 6 months. This information is being used by the California pomegranate marketers to extend the marketing season for 'wonderful' pomegranates.

Publications

Kader, A.A. 2003. Physiology of CATreated Produce. Acta Horticulturae 600:349-353.
Kader, A.A. 2003. A Summary of CA Requirements and Recommendations for Fruits other than Apples and Pears. Acta Horticulturae 600:737-739.
Mitcham, Elizabeth J., Tunya Lee A. Martin, Shijun Zhou, and Adel A. Kader. 2003. Summary of CA for Arthropod Control on Fresh Horticultural Perishable. Acta Horticulturae 600:741-745.
Hess-Pierce, Betty and Adel A. Kader. 2003. Responses of 'Wonderful' Pomegranates to Controlled Atmospheres. Acta Horticulturae 600:751-757.

Progress 01/01/03 to 12/31/03

Outputs
Controlled atmospheres (CA) effectively delayed the ripening of plantains stored for 21 days at 10 or 12.5 C in 2 kPa O2 + 10 kPa CO2 or 2 kPa O2 + 5 kPa CO2 (balance N2). These treatments also were effective in maintaining higher L* and lower a* values which resulted in a better overall appearance of the ripe fruit when compared to fruit stored in air. In general, CA did not adversely effect the acetaldehyde or ethanol concentrations in the flesh of the fruit. The benefits of using CA during 7 days of storage were minimal. CA did not alleviate chilling injury symptoms in plantains stored at 7.2 C for 7 days. Chilling injury was minimal at 10 and 12.5 C in air or in CA; however, CA did reduce subepidermal discoloration in fruit stored at 12.5 C in CA but not at 10 C when compared to air storage. Based on these findings, we suggest that plantains could be stored at temperatures between 7.2 and 10 C for 7-day transit periods in air, but when shipping plantains for longer than 7 days, fruit can be stored at ≥ 10 C in 2 kPa O2 and 5-10 kPa CO2 to avoid increased respiration rates and ripening and to maintain better overall appearance of the ripened fruit.

Impacts
We identified the minimum safe temperature for specialty bananas and plantains to be 10 C as compared to 14 C for Cavendish bananas. Atmospheric modification (2%O2 + 5 to 10% CO2) is effective in quality maintenance of plantains and specialty banana cultivars for up to 21 days at 10 C.

Publications

Kader, Adel A., Noel F. Sommer, and Mary Lu Arpaia. 2002. Postharvest handling systems: tropical fruits, pp. 385-398, In: A.A. Kader (ed.). Postharvest Technology of Horticultural Crops, University of California, Agriculture and Natural Resources Publication 3311.
Kader, Adel A. and James F. Thompson. 2002. Postharvest handling systems: tree nuts, pp. 399-406, In: A.A. Kader (ed.). Postharvest Technology of Horticultural Crops, University of California, Agriculture and Natural Resources Publication 3311.
Kader, Adel, A. and Mikal E. Saltveit. 2003. Atmosphere Modification: pp 229-246. In: Bartz, J.A. and J.K. Brecht (editors). 2003. Postharvest Physiology and pathology of vegetables. Second edition, revised and expanded. Marcel Dekker, Inc., New York.
Kader, Adel A. 2002. Sources of information related to postharvest biology and technology, pp. 1-4, In: A.A. Kader (ed.). Postharvest Technology of Horticultural Crops, University of California, Agriculture and Natural Resources Publication 3311.
Kader, Adel A. 2002. Postharvest biology and technology: an overview, pp. 39-47, In: A.A. Kader (ed.). Postharvest Technology of Horticultural Crops, University of California, Agriculture and Natural Resources Publication 3311.
Kader, Adel A. 2002. Methods of gas mixing, sampling, and analysis, pp. 145-148, In: A.A. Kader (ed.). Postharvest Technology of Horticultural Crops, University of California, Agriculture and Natural Resources Publication 3311.
Mitcham, Elizabeth J., F. Gordon Mitchell, Mary Lu Arpaia, and Adel A. Kader. 2002. Postharvest treatments for insect control, pp. 251-257, In: A.A. Kader (ed.). Postharvest Technology of Horticultural Crops, University of California, Agriculture and Natural Resources Publication 3311.
Kader, Adel A. 2002. Quality and safety factors: definition and evaluation for fresh horticultural crops, pp. 279-285, In: A.A. Kader (ed.). Postharvest Technology of Horticultural Crops, University of California, Agriculture and Natural Resources Publication 3311.
Kader, Adel A. 2002. Standardization and inspection of fresh fruits and vegetables, pp. 287-299, In: A.A. Kader (ed.). Postharvest Technology of Horticultural Crops, University of California, Agriculture and Natural Resources Publication 3311.
Kader, Adel A. and Mary Lu Arpaia. 2002. Postharvest handling systems: subtropical fruits, pp. 375-383, In: A.A. Kader (ed.). Postharvest Technology of Horticultural Crops, University of California, Agriculture and Natural Resources Publication 3311.

Progress 01/01/02 to 12/31/02

Outputs
We evaluated the efficacy of atmospheric modification in controlling decay and maintaining quality of "Wonderful" pomegranates kept at 5, 7.5 or 10C during the first season using air, 2 kPa O2, air + 10 kPa CO2, and 2 kPa O2 + 10 kPa CO2. During the second season we tested the following atmospheres at 5 and 7.5C air, 5 kPa O2, air + 10 kPa CO2, air + 10 kPa C O2 + 15 kPa CO2, 5 kPa CO2 + 10 kPa CO2, 5 kPa O2 + 15 kPa O2 . We found that it is possible to store pomegranates at 7.5C in 5 kPa O2 + 15 kPa CO2 for up to 5 months, provided that the level of latent fungal infections at the time of harvest is low and that pomegranates are sorted carefully after harvest to store only fruits that are free from defects and decay. CO2-enriched atmospheres resulted in higher concentrations of acetaldehyde, ethanol, and ethyl acetate, especially after 4 and 5 months of storage. Accumulation of these volatiles was greater at 7.5C than at 5C, but in both cases the highest concentrations were below the threshold values for detection of off-flavors. Production of ethanol increased sharply in grapes kept in 45 kPa CO2, 0.25 kPa O2, and their combination, and remained relatively constant after transfer to air. In contrast, rate of acetaldehyde production in grapes kept in the same atmospheres remained relatively low during the 12 day exposure, but increased several fold after transfer to air. The superatmospheric O2 atmosphere (80 kPa O2) did not induce ethanolic fermentation in grapes compared to the air control. Activities of pyruvate decarboxylase a (PDC) and alcohol dehydrogenase (ADH) increased in grapes kept in 45 kPa O2 and the combination of 0.25 kPa O2 + 45 kPa CO2, but not in the 0.25 kPa O2 atmosphere. Northern blot analysis revealed that all 3 ADH genes (adh1, adh2, and adh3) were expressed in grapes kept in all treatments throughout the 15-day storage period with adh2 being the predominant gene. These biochemical and molecular data suggest that it is likely that the regulation of adh gene expression may be through post-transcriptional or post-translational control. Also, adh may exist in either homo- or heterodimeric forms in order to be active at particular times under particular atmospheres.

Impacts
The rapidly expanding pomegranate industry in California is using the results of our research in controlled atmosphere storage of pomegranates (5% O2 + 15% CO2 at 7.5C and 90-95% relative humidity) to extend their marketing period. Some of the banana marketing companies are using the results of our research in delaying ripening of partially- ripe bananas by keeping them in 2-4% O2 + 8-12% CO2 at 14C and 90-95% relative humidity (modified atmosphere packaging).

Publications

Kader,Adel.A. 2002. Modified atmospheric storage. Encylopedia of Pest management Marcel Dekker, New York,pp. 504-505.
Kader,Adel.A.(Editor). 2002. Editor Postharvest Technology of Horticultural Crops. Third Edition. University of California, Agriculture and Natural Resources Publication 3311,535 pp.
Kader,Adel A. 2002. Modified atmospheres during transport and storage,pp. 135-144, In:A.A. Kader(ed). Postharvest Technology of Horticultural Crops, University of California, Agriculture and Natural Resources Publication. 3311

Progress 01/01/01 to 12/31/01

Outputs
'Thompson Seedless' grapes were kept at 0C in air (control); 45% CO2; 0.25% O2; or 0.25% O2 + 45% CO2 to investigate the effects of insecticidal controlled atmospheres (ICA) on quality and induction of fermentative metabolism. Quality attributes including firmness, soluble solids content, titratable acidity, pH, color and visual quality, and production of fermentative volatiles (mainly acetaldehyde and ethanol) and activities of corresponding enzymes that catalyze their production, pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH), were measured initially and after 4, 8, and 12 days of exposure and after 1 and 3 days following transfer to air at 0C. Although quality attributes were not significantly affected by ICA treatments compared to air control, production of both acetaldehyde and ethanol increased by 5 to 10 fold and 40 to 50 fold, respectively, over a 12-day exposure to ICA with greatest increase found in grapes kept in 45% CO2, while the levels of these volatiles remained low and relatively constant in air control fruit. Concentration of acetaldehyde in grapes kept in 45% CO2 decreased by 70% after transfer to air for 3 days 0C, while ethanol concentration decreased slightly. Activities of PDC and ADH increased significantly during exposure to ICA, particularly under 45% CO2, with slight reduction on day 12 of storage. ADH activity in grapes kept in 45% CO2 sharply increased after transfer to air for 1 day. Low O2 seemed to reduce the effect of high CO2 on both production of the volatiles and enzymatic activity as indicated by lower accumulation of acetaldehyde and ethanol and lower activities of PDC and ADH in grapes kept in 0.25% O2 + 45% CO2 compared to those kept in 45% CO2 alone.

Impacts
We have demonstrated that fruits tolerate stress caused by very low oxygen concentrations and/or elevated carbon dioxide concentrations (that can be used for insect and/or decay control) for 10 to 15 days at their optimal storage temperatures. Thus, such atmospheres can be used during transportation and/or short-term storage. Decay control can be achieved by keeping table grapes in 15% CO2 enriched atmospheres (instead of using SO2) at 0C for up to one month.

Publications

Kader, A.A. 2001. Physiology of CA treated produce. CA2001 8th International Controlled Atmosphere Research Conference, July 8-13, 2001, Rotterdam, The Netherlands. 1 p.
Kader, A.A. 2001. A summary of CA requirements and recommendations for fruits other than apples and pears. CA2001 8th International Controlled Atmosphere Research Conference, July 8-13, 2001, Rotterdam, The Netherlands. 1 p.
Hess-Pierce, M. and A.A. Kader. 2001. Responses of 'Wonderful' pomegranates to controlled atmospheres. CA2001 8th International Controlled Atmosphere Research Conference, July 8-13, 2001, Rotterdam, The Netherlands. 1 p.
Chairat, Raywat and Adel A. Kader. 2001. Fermentative metabolism and quality of 'Thompson seedless' grapes in response to insecticidal controlled atmosphere. HortScience 36(3):471.

Progress 01/01/00 to 12/31/00

Outputs
Raywat Chairat (Ph.D. in Plant Biology graduate student) is studying respiratory metabolism of table-grapes subjected to insecticidal controlled atmospheres (CA) of 0.25% O2 +/- 45% CO2 at 0C for up to 15 days. His goals are to elucidate the biochemical basis of tissue recovery and repair following the CA stress and to identify post-treatment factors that contribute to expedited and full recovery of the grapes (as indicated by reduction of acetaldehyde and ethanol concentrations). In collaboration with Professor Doug Adams, Department of Viticulture and Enology, Mauro Zanuz (Ph.D. in Agricultural Chemistry graduate student) is investigating the effects of fungistatic CO2-enriched CA in comparison with SO2 treatment for control of grey mold (Botrytis cinerea) on table-grapes, kept at 0C for up to 2 months, on their flavor quality (as indicated by sugars, organic acids, phenolic compounds, and aroma volatiles) and on their total antioxidant activity. Clara Pelayo (Ph.D. in Plant Biology graduate student) is nearing completion of her research on factors influencing flavor quality of strawberries (genotypes, harvest date, storage time and fungistatic CO2 atmosphere). One of her goals is to identify the reasons for loss of flavor quality before end of postharvest-life based on appearance and textural quality. She found that the total content of aroma compounds and the methyl/ethyl esters ratio may be two of the multiple factors determining the overall strawberry fruit flavor. Dr. Mohamed Benichou (Postdoctoral Researcher) examined the efficacy of treatments with 1-methylcyclopropene (1-MCP) gas in delaying ripening of partially-ripe (color 2, 3, and 4) bananas. Also, he determined the influence of 1-MCP (at the most effective concentration-exposure duration combination = 1 ppm for 6 hours) on ethylene biosynthesis.

Impacts
Our findings as to the mode of action of oxygen, carbon dioxide, and ethylene on postharvest physiology and quality maintenance of fruits have resulted in several refinements in selecting optimum controlled atmospheres (CA) for 'Bartlett' pears, plums, pomegranates, and bananas. Since we demonstrated that postharvest-life in air or in the optimum CA conditions is shorter when based on flavor than when based on appearance; other researchers and commercial users of CA technology are paying more attention to flavor quality.

Publications

Kader, Adel A. and Christopher B. Watkins. 2000. Modified atmosphere packaging - toward 2000 and beyond. HortTechnology 10(3):483-486.
Kader, Adel A. and Shimshon Ben-Yehoshua. 2000. Effects of superatmospheric oxygen levels on postharvest physiology and quality of fresh fruits and vegetables. Postharvest Biology and Technology 20:1-13.
Kader, Adel, Betty Hess-Pierce, Maria I. Gil, Francisco A. Tomas-Barbern, and Chaudra Hallock. 2000. Phytonutrients in fruits and nuts. Perishables Handling Quarterly issue no. 102, pp. 2-4
Kader, Adel, Jim Thompson, and Kathi Sylva. 2000. Storing fresh fruits and vegetables for better taste. University of California, Division of Agriculture and Natural Resources, Publication #21590.
Lee, Seung K. and Adel A. Kader. 2000. Preharvest and postharvest factors influencing vitamin C content of horticultural crops. Postharvest Biology and Technology 20:207-220.
Pelayo, Clara, Betty Hess-Pierce, Susan E. Ebeler, and Adel A. Kader. 2000. Postharvest life, quality and flavor characterization of three strawberry cultivars kept in air or CO2-enriched atmospheres. HortScience 35(3):411.

Progress 01/01/99 to 12/31/99

Outputs
Initial quality and rate of deterioration of fresh-cut fruit products depend upon the genotype, preharvest climatic conditions and cultural practices, harvesting method, and postharvest processing and handling procedures. Temperature and relative humidity are the most critical factors in preserving quality of these products. Even under optimum processing and handling conditions, postcutting-life based on flavor is shorter than that based on appearance. Our research goal is to identify the reasons for the flavor loss and possible treatments to slow it down and to restore the ability of the fruit tissue to produce the desirable aroma compounds. Postcutting flavor-life ranges between 2 and 14 days at 0 to 5C and 90 to 95% relative humidity, depending on the fruit species and cultivar, ripeness stage when cut, preprocessing storage duration and conditions, and processing and packaging methods. Fresh-cut fruit products with potential storage-life of 10-14 days include apple wedges, kiwifruit slices, pineapple wedges, and pomegranate arils; those with potential storage-life of 2-9 days include mango cubes, nectarine and peach wedges, pear wedges, persimmon slices, and strawberry slices. In most cases, tissue browning, loss of textural integrity, and loss of flavor are the primary causes of quality deterioration. Calcium treatments are effective in firmness retention and in delaying browning, especially when combined with ascorbic acid and cysteine (pH 7) treatments. Ethylene scrubbing and modified atmosphere packaging (to maintain 2-5% oxygen and 8-12% carbon dioxide) can be useful supplements to temperature management in maintaining quality of fresh-cut fruit products. Our studies on polyphenolic composition and total antioxidant capacity of fruits show that pomegranates and plums, and to a lesser extent, nectarines, peaches, and pears have good total antioxidant capacities in comparison with red wine.

Impacts
We identified the optimum ripeness stage, cutting method, temperature and relative humidity, atmospheric composition, and packaging for mango and pineapple slices. This information will help processors and handlers of fresh-cut fruits in maintaining quality of these products until they reach the consumers. Our studies on polyphenolic composition and total antioxidant capacity of fruits show that pomegranates and plums, and to a lesser extent, nectarines, peaches, and pears have good total antioxidant capacities in comparison with red wine.

Publications

Holcroft, Deirdre M. and Kader, Adel A. 1999. Carbon dixoide-induced changes in color and anthocyanin synthesis of stored strawberry fruit. HortScience 34(7):1244-1248.

Progress 01/01/98 to 12/31/98

Outputs
Changes in color of strawberry fruit kept in CO2-enriched atmospheres at 5C for 10 days are due to a combination of a reduction in biosynthesis and pH-induced changes in color expression and stability of the anthocyanin pigment. Other factors that may affect anthocyanin stability, such as copigmentation and the activity of Beta-glucosidase in combination with peroxidase, may be affected by CA storage and warrent further research. The arils of the pomegranates stored in air were deeper red than the initial controls and than those stored in CO2-enriched atmospheres. This increased color was associated with increased anthocyanin concentration. Arils from fruit stored in air enriched with 10 kPa CO2 had a lower anthocyanin concentration than air-stored fruit, and atmospheres enriched with 20 kPa CO2 had even lower levels, possibly from suppressed anthocyanin biosynthesis. Anthocyanin concentration correlated well with the activity of phenylalanine ammonia lyase but not with glucosyltransferase activity. Moderate CO2 atmospheres (10 kPa) prolong the storage life and maintain quality of pomegranates, including adequate red color intensity of the arils. Fruit and oil quality of Ascolano and Manzanillo olive cultivars deteriorated more rapidly than that of Mission and Sevillano olives. Black-ripe Manzanillo and Ascolano olives could be stored with good air circulation at 5C for 2 and 4 weeks, respectively, whereas Mission and Sevillano cultivars could be stored for 6-8 weeks.

Impacts
(N/A)

Publications

KADER, A.A. AND KADER, A. 1997. Horticulture, pp. 353-356. In: Goreham, Gary L. (ed), Encyclopedia of Rural America, The Land and People, Vol. 1 A-L, ABC-CLIO, Santa Barbara, CA.
KADER, A.A., ET AL. 1998. Technologies to extend the refrigerated shelf life of fresh fruits, pp. 419-434. In: Taub, I.A. and Singh, R.P. (eds). Food Storage Stability. CRC Press, Boca Raton, FL.
HOLCROFT, D.M., ET AL. 1998. Effect of carbon dioxide on anthocyanins, phenylalanine ammonia lyase and glucosyltransferase in the arils of stored pomegranates. J. Amer. Soc. Hort. Sci.
AGAR, I.T., HESS PIERCE, B., SOUROUR, M.M., AND KADER A.A. 1998. Quality of fruit and oil of black-ripe olives is influenced by cultivar and storage period. J. Agric. Food Chem. 46:3415-3421.

Progress 01/01/97 to 12/01/97

Outputs
Mild stress concentrations of CO2 used in controlled atmosphere (CA) environments reduce respiration rate, inhibit ethylene production and action, retard compositional changes, alleviate some physiological disorders, and retard decay incidence. Elevated-CO2 atmospheres inhibit activity of ACC synthase (key regulatory site of ethylene biosynthesis), while ACC oxidase activity is stimulated at low CO2 levels and inhibited at high CO2 concentrations and/or low O2 levels. Ethylene action is inhibited by elevated-CO2 atmospheres. Optimum CA environments retard loss of chlorophyll (green color), biosynthesis of carotenoids (yellow and orange colors) and anthocyanins (red and blue colors), and biosynthesis and oxidation of phenolic compounds (brown color). CAs slow down the activity of cell wall-degrading enzymes that cause fruit softening. CAs influence flavor quality by reducing loss of acidity, starch to sugar conversion, interconversion of sugars, and biosynthesis of flavor volatiles. Retention of ascorbic acid and other vitamins results in better nutritional quality of fruits kept in CA environments. Postharvest life of fruits, such as 'Bartlett' pears and strawberries, on the basis of appearance is longer than that based on textural attributes, which is longer than taste-life. Postharvest losses of acids, sugars, and the ability of fruits to produce their characteristic aroma volatiles are the primary factors in determining taste-life of harvested fruits.

Impacts
(N/A)

Publications

GORNY, JAMES R. AND KADER, ADEL A. 1997. Low oxygen and elevated carbon dioxide atmospheres inhibit ethylene biosynthesis in preclimacteric and climacteric apple fruit. J. Amer. Soc. Hort. Sci.
KADER, A.A. 1997. Produce Facts: Mango, recommendations for maintaining postharvest quality. Perishables Handling 89:15-16.
KADER, A.A., OLDS, M.A., MOYER, P.V., AND ZAGORY, D. 1997. Modified atmospheres-an indexed reference list with emphasis on horticultural commodities, Suppl. #7. Postharvest Hort. Series #14, July 1997, 67
KADER, A.A. 1997. A summary of CA requirements and recommendations for fruits other than apples and pears, p. 1-34. In Kader, A.A. (ed), CA-97 Proceedings Vol. 3. Postharvest Hort. Series #17, U.C. Davis,
KADER, A.A. 1997. Biological bases of CO2 effects on postharvest-life of horticultural perishables. CA-97 Prog. and Abstr., Seventh Intl. Controlled Atmosphere Res. Conf., July 13-18, 1997, U.C. Davis,

Progress 01/01/96 to 12/30/96

Outputs
Pear slices cut from partially ripe pears (6-10 lb-force firmness) held in air +10 or 20% CO2 treatments exhibited accelerated tissue browning compared to air controls. Our data indicate that pear slices are susceptible to high CO2 injury and the symptoms expressed are similar to those observed in whole fruit. An atmosphere of 0.25% O2 was not effective in reducing cut surface browning. Only in the complete absence of O2 could cut surface browning be stopped. Various concentrations of calcium lactate and/or ascorbate were also tested on 'Bartlett' pear tissue discs to determine the optimal levels to prevent browning and loss of flesh firmness. Calcium lactate was chosen as a calcium source to avoid the off flavor caused by the use of CaCl2. A combination of 1% calcium lactate and 2% ascorbate was the most effective treatment to prolong the shelf life of sliced pears. Based on our research on fresh-cut peaches and nectarines we have determined that: 1) whole fruit between 3 to 6 lb-force firmness were optimal for fresh-cut stone fruit; 2) shelf life based on visual appearance is significantly influenced by variety; 3) shelf life based on visual appearance is limited by loss of sheen and gloss of the cut surface (likely due to localized dehydration of the cut surface) and endocarp breakdown; and 4) controlled atmospheres do not significantly extend the shelf life of these products. We determined that shelf life based on visual appearance is not equivalent to shelf life based on eating quality.

Impacts
(N/A)

Publications

KADER, ADEL. 1996. In-plant storage, pp. 274-277. In: Micke, W.C. (ed.). Almond production manual. Publication 3364, University of California, Division of Agriculture and Natural Resources, Oakland, CA.
KADER, ADEL A. and BARRETT, DIANE M. 1996. Classification, composition of fruits, and postharvest maintenance of quality, p. 1-24. In: Somogyi, et al. (eds.). Processing fruits: science and technology, Vol. 1. Biology, principles, and appli
KADER, ADEL, THOMPSON, JAMES and REID, MICHAEL. 1996. Improving the system, p. 23-26. In: Produce Services Sourcebook, The Packer, Lincolnshire, IL.
HOLCROFT, D.M., GIL, M. I., and KADER, A.A. 1996. Effect of carbon dioxide on stability of anthocyanins and other phenolic compounds during storage of fresh strawberries. HortScience 31:590.

Progress 01/01/95 to 12/30/95

Outputs
High levels of carbon dioxide can be effective in the retardation of ripening and control of decay-causing pathogens and insect infestation of some fruits. Our objective has been to identify key mitochondrial enzymes and pathways that regulate the fruit's response to CO2 actions. Oxygen uptake of avocados stored in air+20% CO2 (17% O2) was depressed compared to the air-stored fruit, whereas the fruit stored in air+40% CO2 (13% O2) had an elevated respiration rate. Climacteric fruit treated with 20% CO2 at 10C had increased pyruvate dehydrogenase (PDH) activity, decreased cytochrome oxidase (CytOx) activity and double the alternative oxidase (AltOx) activity compared to air-stored fruit. Air+40% CO2-stored fruit had reduced PDH and CytOX activities and 50% more AltOx activity than the control fruit. Respiratory metabolism of avocados returned to normal upon transfer from CO2-enriched atmospheres to air indicating the fruit's ability to recover from high CO2 stress. To elucidate the mode of O2 and CO2 actions on ethylene biosynthesis, Golden Delicious apple fruit were placed at 0C in air; air+5% CO2; 2% O2; or 2% O2+5% CO2 and then sampled monthly for four months. IN VITRO ACC synthase activity and ethylene biosynthesis rates were lowest in fruit treated with 5% CO2+2% O2, while air treated fruit had the highest ethylene biosynthesis rate and IN VITRO ACC synthase activity. Fruit treated with air+5% CO2, or 2% O2%, had intermediate ethylene and IN VITRO ACC synthase activities.

Impacts
(N/A)

Publications

KADER, A. A. and KITINOJA, L. 1994. Postharvest handling of perishable crops, p. 109-116, In: Huphery, S. et al. (editors). Small Farm Handbook, Publ. SFP001, ANR Publications, Univ. Calif., Oakland, CA.
MASSANTINI, R. and KADER, A. A. 1995. Storability and quality preservation of sliced kiwifruits. Industrie Alimentari 34:357-360. (In Italian with English summary).
BANKS, N. H., CLELAND, D. J., CAMERON, A. C., BEAUDRY, R. M., and KADER, A. A. 1995. Proposal for a rationalized system of units for postharvest research in gas exchange. HortScience 30(6):1129-1131.
COLELLI, G. and KADER, A. A. 1994. CO2-enriched atmospheres reduce postharvest decay and maintain good quality in highly perishable fruits. Proc. COST 94 Workshop, April 22-23, 1993, Milan, Italy, pp. 137-148.
KADER, A. A. and MITCHAM, B. 1995. Standardization of quality. Perishables Handling 81:7-9.
KADER, A. A. 1995. Suppression of postharvest diseases by controlled atmospheres. Perishables Handling 82:7-9.
THOMPSON, J. and KADER, A. A. 1995. A simplified compatability chart for fruits and vegetables during short-term transport or storage. Perishables Handling 83:6-7.

Progress 01/01/94 to 12/30/94

Outputs
Mild stress concentrations of O2 and/or CO2 used in controlled atmosphere (CA) environments reduce respiration rate, inhibit ethylene production and action, retard compositional changes, alleviate some physiological disorders, and inhibit decay of fruits. Optimum CA environments retard loss of chlorophyll (green color), biosynthesis of carotenoids (yellow and orange colors) and anthocyanins (red and blue colors), and biosynthesis and oxidation of phenolic compounds (brown color). CAs slow down the activity of cell wall-degrading enzymes that cause fruit softening. CAs influence flavor quality by reducing loss of acidity, starch to sugar conversion, and biosynthesis of volatiles. Retention of ascorbic acid and other vitamins results in better nutritional quality of intact and cut fruits kept in CA environments. Low-O2 atmospheres (below 8%) reduce ethylene production in apples and pears by inhibiting activities of ACC synthase and ACC oxidase. Elevated-CO2 atmospheres inhibit activity of ACC synthase, while ACC oxidase activity is stimulated at low CO2 levels and inhibited at high CO2 concentrations. Ethylene action is inhibited by low-O2 and/or elevated-CO2 atmospheres. Severe stress concentrations of O2 reduce pyruvate dehydrogenase activity while pyruvate decarboxylase, alcohol dehydrogenase, and lactate dehydrogenase are induced or activated in avocadoes, pears, and strawberries. This causes accumulation of acetaldehyde, ethanol, and/or lactate, which may influence flavor quality.

Impacts
(N/A)

Publications

MATEOS, M., KE, D-Y., CANTWELL, M., AND KADER, A.A. 1993. Phenolic metabolism and ethanolic fermentation of intact and cut lettuce exposed to CO2-enriched atmospheres. Postharvest Biol. and Technol. 3:225-233.
KE, D-Y., MATEOS, M., SIRIPHANICH, J., LI, C-Y., AND KADER, A.A. 1993. Carbon dioxide action on metabolism of organic and amino acids in crisphead lettuce. Postharvest Biol. and Technol. 3:235-247.
ARPAIA, M.L., MITCHELL, F.G., AND KADER, A.A. 1994. Postharvest physiology and causes of deterioration, p. 88-93, In: Hasey, J.K. et al. (editors). Kiwifruit Growing and Handling, Univ. of Calif., DANR Pub. 3344.
KE, D-Y., EL-WAZIR, F., COLE, B., MATEOS, M., AND KADER, A.A. 1994. Tolerance of peach & nectarine fruits to insecticidal controlled atmospheres as influenced by cultivar, maturity, & size. Postharvest Biol. & Technol. 4:135-146.
KADER, A.A AND KE, D-Y. 1994. Controlled atmospheres, p. 223-236, In: Paull, R.E. & J.W. Armstrong (eds). Insect Pests & Fresh Hort. Products: Treatments and Responses. CAB International, Wallingford, UK.
KADER, A.A. 1994. Regulation of fruit physiology by controlled/modified atmospheres. Abstracts, XXIVth International Horticultural Congress; 21-27 August, 1994; Kyoto, Japan, p. 15.
KADER, A.A. 1994. Mechanisms of plant responses to low oxygen and high carbon dioxide environments. Recent Advances in Postharvest Physiology & Molecular Bio.

Progress 01/01/93 to 12/30/93

Outputs
Mild stress concentrations of low O2 and/or high CO2 reduced respiration rate offruits and vegetables but did not induce ethanol and/or lactate fermentation. Under severe stress levels of O2 and/or CO2, the accumulations of acetaldehyde, ethanol, ethyl acetate, and/or lactate are enhanced by lower O2 and/or higher CO2 concentrations, higher temperatures, longer exposures, and more advanced fruit maturity. The fermentation enzymes pyruvate decarboxylase (PDC), alcohol dehydrogenase (ADH), and lactate dehydrogenase (LDH) could be under molecular and/or metabolic control. If the level of a given enzyme is limited in a commodity, then the molecular control through biosynthesis of that enzyme or a specific isozyme may be critical in inducing fermentative metabolism. But if the enzyme level is quite high, then the metabolic control through changes in pH, substrates, cofactors, and/or inhibitors may play a dominant role in regulating fermentative metabolism. Low O2 and/or high CO2 atmospheres decrease cytoplasmic pH, reduce ATP level, increase pyruvate and fructose-6-phosphate concentrations, and/or increase NADH/NAD ratio, depending on the commodity. PDC is activated by a decrease in pH and activated by increased concentrations of pyruvate, NADH. LDH is inhibited by a decrease in pH and activated by increased concentrations of pyruvate, NADH, fructose-6-phosphate and a decreased ATP level.

Impacts
(N/A)

Publications

Progress 01/01/92 to 12/30/92

Outputs
During exposure of `Bartlett' pears to 0.25 percent 02 at 20C, loss of greennessand ethylene production were inhibited and CO2 production substantially decreased. Pears that had been stored for 2 weeks at 0C ripened normally, while those that had been stored for 8 weeks at 0C failed to recover normal ethylene and CO2 production upon transfer to air after a 4-day exposure to 0.25 percent 02 at 20C. Most of the latter fruit were injured as indicated by skin browning. Acetaldehyde and ethanol content increased considerably with ripening of control fruit. Although 0.25 percent 02-treated fruit developed yet higher acetaldehyde and ethanol contents during treatment, the concentrations returned to or below normal during subsequent exposure to air. Pears exposed to 0.25 percent 02 had increased pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activities that remained high after ripening in air for 6 days. Three ADH isozymes were discernible in the 0.25 percent 02-treated pears, whereas only one, ADH2, was found in control fruit. Fruits of `Bing' cherry, `Red Jim' nectarine, `Angeleno' plum, `Yellow Newtown' and `Granny Smith' apples, and `20th Century' pear were treated with 0.25 percent or 0.02 percent 02 (balance N2) at 0, 5, or 10C to study the effects of these low 02 atmospheres on their postharvest physiology and quality attributes. Development of alcoholic off-flavor was associated with ethanol accumulation, which was the most common and important detrimental effect that limited fruit tolerance to low 02.

Impacts
(N/A)

Publications

KADER, A.A. (Editor) 1992. Postharvest technology of horticultural crops. Publication 3311, University of California, Division of Agriculture and Natural Resources, Oakland, CA, 296 pp.
KADER, A.A. 1992. Sources of information related to postharvest biology and technology, p. 1-2, in: A.A. Kader (ed.). Postharvest technology of horticultural crops. Publ. 3311, University of California, Division of Agriculture and Natural.
KADER, A.A. 1992. Postharvest biology and technology: an overview, p. 15-20, In: A.A. Kader (ed.). Postharvest technology of horticultural crops. Publ. 3311, University of California, Division of Agriculture and Natural Resources, Oakland,.
KADER, A.A. 1992. Modified atmospheres during transport and storage, p. 85-92, In: A.A. Kader (ed.). Postharvest technology of horticultural crops. Publ. 3311, University of California, Division of Agriculture and Natural Resources, Oakl.
KADER, A.A. 1992. Methods of gas mixing, sampling, and analysis, p. 93-95, in: A.A. Kader (ed.). Postharvest technology of horticultural crops. Publ. 3311, University of California, Division of Agriculture and Natural Resources, Oakland,.
KADER, A.A. 1992. Quality and safety factors: definition and evaluation for fresh horticultural crops, p. 185-189, In: A.A. Kader (ed.). Postharvest techno.

Progress 01/01/91 to 12/30/91

Outputs
Fruits of 'Bartlett' pear at green and yellow stages were kept in 0.25% 02 (balance N2), 80% CO2 (balance 02), or 0.25% 02 + 80% CO2 (balance N2) for 1, 2, or 3 days followed by transfer to air at 20C for 3 days to study the effects of these controlled atmosphere (CA) on anaerobic products and enzymes. All the three CA treatments caused accumulation of ethanol, acetaldehyde, and ethyl acetate. The yellow pears were more sensitive to CA treatments as indicated by occurrence of visual injury, enhanced activity of pyruvate decarboxylase, and higher concentrations of the anaerobic volatiles. For the green pears, the 0.25% 02 treatment dramatically increased alcohol dehydrogenase (ADH) activity, which was associated with the induction of one ADH isozyme; exposure to 80% CO2 slightly increased ADH activity; however, the combination treatment of 0.25% 02 + 80% CO2 had lower ADH activity than 0.25% 02 alone.

Impacts
(N/A)

Publications

NANOS, G.D. 1991. Low 02 effects on pear fruit respiratory metabolism. Ph.D. dissertation, Department of Pomology, University of California, Davis.

Progress 01/01/90 to 12/30/90

Outputs
Pear pericarp discs kept in air + 5 to 20% C02 exhibited lower C2H4 production rates, lower activities of 1-aminocyclopropane carboxylic acid (ACC) synthase and ACC oxidase (ethylene forming enzyme, EFE), and remained greener than fruit discs stored in air at 20/o/C for 8 days. ACC oxidase activity and ethylene production rate increased in pear tissue exposed to air + 1% C02, but did not influence other parameters of ripening, such as skin color. The ability of mature-green `Bartlett' pear to withstand low 02 stress 0.25% 02 for 4 days at 20/o/C was examined. Loss of green skin color was inhibited and C02 and C2H4 production rates were reduced under low 02 but proceeded normally upon transfer to air. Pear exposed to 0.25% 02 had lower pyruvate kinase activity and higher pyruvate decarboxylase and alcohol dehydrogenase activities relative to air-treated pears. Tolerance of low 02 decreased with ripening and the blossom-end area of the fruit was more prone to anaerobiosis, as indicated by higher alcohol dehydrogenase activity and ethanol concentration.

Impacts
(N/A)

Publications

KADER, AA 1991. Current and future research needs on postharvest biology and technology of fruits and vegetables. p. 347-351 (English) and p. 183-187 (Spanish), In: E.M. Yahia and I. Higuera (editors). Proceedings of the National Symposium.
KADER, A.A. and THOMPSON, J.F. 1991. Book reviews. Perishables Handling 71:11-13.
NANOS, G.D., ROMANI, R.J. and KADER, A.A. 1991. Activities of some glycolytic enzymes in `Bartlett' pears kept in 0.25% 02. HortScience 26(6):79.
KADER, A.A. 1991. Maturity indices, quality factors, standardization, and inspection of horticultural products. p. 217-222 (English) and p. 37-42 (Spanish), In: E.M. Yahia and I. Higuera (editors). Proceedings of the National Symposium on.