Washington Tree Fruit Research Commission

Research Reports

Coatings and other treatments to improve cherry quality (2007)

FINAL PROJECT REPORT
WTFRC Project #CH-05-501
YEAR 0/0
Organization Project #
Title:Coatings and other treatments to improve cherry quality
PI:Jinhe Bai
Organization:Oregon State Univ. 541-386-2030 jinhe.bai@oregonstate.edu Mid-Columbia Ag. Ctr. 3005 Experiment Station Dr Hood River, Oregon 97031
 PDF version of report

Co-PIs

Anne Plotto

USDA, ARS

863-293-4133  plotto@citrus.usda.gov

Citrus Res. Lab

600 Ave S. NW

Winter Haven, Florida 33881

Collaborators

Robert Bailey, Clark Seavert, Robert Spotts, Roberto Núñez-Elisea, Xinhua Yin, Kristi Barckley and Debra Laraway

Significant findings

For stem coatings, paraffin + polyethylene decreased water loss and browning, decreased stem detaching, and water loss.  However, other film forming formulations did not affect stem quality.  GA3 dips slowed down stem browning of ‘Bing’ cherries.

Results and discussion

Clamshell (Fig. 1-4): Currently commercial clamshells are very inefficient because 2-5% of the total surface area is exposed to air (Fig. 1).  This opening allows fruit weight to decrease more than 5% when stored at 33°F for 14 – 21 days.  The critical point at which fruits and vegetables deteriorate due to water loss is at about 5%.  Thus, as a result of this exposure to air, cherry stems dry or turn brown, and fruit shrink and deteriorate.We developed a better product – our new clamshell significantly decreased fruit weight loss  and nearly doubled cherry shelf life.  This new clamshell includes smaller openings with the opening ratio to total surface area is from 0.05-0.50% (Fig. 1).  Because of the small opening, the relative humidity (RH) inside the clamshell with fruit was 5-6% higher than the commercial clamshell (Fig. 2).  The water loss rate of fruit in the new clamshell was only half in comparison with which in the commercial clamshell (Fig. 3).  Fruit in the new clamshell had high flesh firmness, less stem discoloration (data not shown), and less incidence of pitting at 33°, 50° and 68°F (1°, 10°, and 20°C), respectively (Fig. 4).The result with our clamshell is that fruit will store longer, have better quality, and ultimately have happier consumers.

Commercial clamshell

Experimental clamshell
Fig. 1.  Commercial (left, with large openings) and experimental (right, with small opening) clamshells (2006).

 
              Ethanol release powder (Fig. 5-6 and Table 3): The presence of an ethanol-release pad (Antimold Mild®, Freund Industrial, Japan) in the clamshell allows ethanol vapor to diffuse gradually (Fig. 5).  It is made from ethanol absorbed onto silica gel that is packed in a special film, laminated with ethylene-vinylacetate and a proprietary Japanese paper, which regulates ethanol diffusion.  The ethanol pad was glued on the top lid of clamshell.

            Softening of fruit and browning of stems were retarded by ethanol pads (Fig. 6).  Ethanol treatment affects ripening and senescence in some fruit and vegetables (Bai et al., 2004; Plotto et al., 2006; Suzuki et al., 2004).  Ethanol vapor treatment of tomato fruit suppressed the climacteric respiratory rise, lycopene synthesis, and chlorophyll breakdown (Saltveit and Mencarelli, 1988).  Ethanol injected into the seed cavity of muskmelon and honeydew inhibited softening (Ritenour et al., 1997).  Furthermore, ethanol solution prolonged the vase life of cut carnations by suppressing respiration and transpiration (Pun et al., 2001).

 

Fruit coating and other dipping treatments (Table 1-3):  The following experimental or commercial coatings and other chemical agents were used, alone or in combination.  1) Natural or artificial film-formers, such as carnauba, resin, chitosan or sucrose fatty acid esters which provide a  barrier for protecting against moisture loss while moderately modifying fruit internal atmosphere;  2) Antioxidant agents, such as acetyl cysteine, ascorbic acid or 4-hexyl resorcinol to protect fruit and stems from discoloration;  3) Calcium salts which maintain membrane system of plant cells and increase fruit firmness;  4) Gibberellic acid, a plant regulator which may delay the senescence process of fruit; and 5) A sanitizer, such as peroxyacetic acid.  Dipped fruit were stored at 33°, 50°, or 68°C to simulate the commercial storage and marketing in cold room or container car, cold shelf, or ambient shelf.  We conducted the coating experiments for two years (2004 and 2005).  Treatments that showed good results in 2004 were evaluated again in 2005.

Sucrose fatty acid esters, resins and vegetable oil emulsions are major commercial coatings for cherries.  Most of these coatings, more or less, prevented moisture loss of fruit (Table 1).  Fruit coated with sucrose fatty acid ester had the highest gloss (data not shown).  However, these coatings did not significantly improved appearance of cherries (Table 2).  Chitosan is a relatively new coating material.  Chitosan forms a film when applied on fruit surface, which resulted in reducing moisture loss, modifying internal atmosphere of fruit, and reducing decay (Bai and Baldwin, 2002).  Chitosan also decreased loss of fruit firmness and prolonged stem retention (Table 2).  El Gaouth (1991, 1992, and 1997) reported that chitosan coating reduce decay for tomato, pepper and strawberries, therefore it could be a promising coating for cherries, too

 Stem coating and other dipping treatments (Table 4):  In 2004, cherry stems were dipped in different coatings, Ca salts and GA3, respectively, using a screen system which holds the fruit when stems are in the solution.  GA3 and chitosan coating decreased stem browning of ‘Bing’ and ‘Lapins’ cherries, respectively (Table 4).  In 2005, ‘Lapins’ cherry stems were dipped in chitosan, GA3, paraffin + polyethylene, carnauba or shellac coating/solution. Paraffin + polyethylene coating decreased water loss and browning, and prevented stem detaching (data not shown).  We observed surface wax and stomata structure of cherry stem under scanning electricity microscopy (SEM ).  The results shows that there were clear stomata on the stem and the coating did not cover the stomata well.  Surface natural wax was destroyed rapidly at ambient temperature.  Shellac and paraffin coating on the surface cracked easily, but chitosan coating showed a good cover on the stem surface (data not shown).

 

  

Literature cited

Bai, J., Abe, K., Kurooka, H.  1990.  Effect of harvest maturity, perforation ratio of polyethylene package and storage temperature on quality of Hassaku (Citrus hassaku hort. Ex Tanaka) fruit.  J. Japan. Soc. Cold Preserv. Food. 16:97—104. 

Bai, J., Baldwin, EA. 2002.  Postprocessing dip maintains quality and extends the shelf life of fresh-cut apple.  Proc. Fla. State Hort. Soc. 115:297-300. 

Bai, J., E.A. Baldwin, R. Soliva-Fortuny, J.P. Mattheis and J.K.Brecht. 2004. Effect of pretreatment of intact ‘Gala’ apple with ethanol vapor, heat or 1-methylcyclopropene on quality and shelf life of fresh-cut slices. J. Amer. Soc. Hort. Sci. 129:583-593.  

El Gaouth, A., Arul, J., Wilson, C., Benhamou, N. 1997. Biochemical and cytochemical aspects of the interactions of chitsan and Botrytis cinerea in bell pepper fruit.  Postharvest Biol. Technol.  12:183-194. 

El Gaouth, A., Ponnoampalam, R., Castaigne, F., Arul, J. 1992. Chitosan coating to extend the storage life of tomatoes.  HortSci.  27:1016-1018 

El Gaouth, A., Arul, J., Ponnoampalam, R., Boulet, M. 1991. Chitosan coating effect on storability and quality of fresh strawberries.  J. Food Sci. 56.: 1618-1620. 

Patten, K., Patterson, ME., Kupferman, E.  1983.  Reduction of surface pitting in sweet cherries.  Post Harvest Pomology Newsletter, 1 (2): pp6. 

Plotto, A., J. Bai, J.A. Narciso, J.K. Brecht, and E.A. Baldwin. 2006. Ethanol vapor prior to processing extends fresh-cut mango shelf-life by decreasing spoilage, but does not always delay ripening. Postharvest Biol. Technol. 39: 134-145. 

Pun, U.K., Rowarth, J.S., Barnes, M.F., and Heyes, J.A.  2001.  The role of ethanol or acetaldehyde in thebiosynthesis of ethylene in carnation (Dianthus caryophyllus L.) cv. Yellow Candy.  Postharvest Biol. Technol. 21:235-239. 

Ritenour, M.A., Mangrich, M.E., Beaulieu, J.C., Rab, A., and Saltviet, M.E.  1997.  Ethanol effect on the ripening of climacteric fruit.  Postharvest Biol. Technol. 12:35-42. 

Saltveit, M.E., and Mencarelli, F.  1988.  Inhibition of ethylene synthesis and action in ripening tomato fruit by ethanol vapors.  J. Amer. Soc. Hort. Sci. 113:572-576. 

Suzuki, Y., Uji, T., Terai, H.  2004. Inhibition of senescence in broccoli florets with ethanol vapor from alcohol powder.  Postharvest Biol. Technol. 31: 177-182.

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