Dear Seied,

This is typical disorders of Red delicious - superficial scald.

a-farnesan oxidation in skin of apples is reason which causes this disorder as theoretical background.

However, There could be a several practical reasons:

1. Not proper temperature in cold storage - should be not more than +1 C,

2. Store over ripening fruits (more likely)

3. Storage is more than 6-8 month (each cultivar has storage ability threshold time )

4. Not proper ventilation - too much Ethylen and CO2 during storage

5. A lot evidences - over fertilizing by nitrogen of apple trees

Solutions to avoid in for future cases:

1. Strict temperature control during storage

2. Proper harvest time according of starch indexes

3. DPA treatment - This is very good solution

4. Calcium spray 2 times before of harvest.

hope this information will helps you.

if you need more particular information on storage please let me know.

Best regards.

Zviad Bobokashvili

There are three groups of pigments in apple skin and the concentrations of all three pigments change during the season. Chlorophylls are the green pigments responsible for photosynthesis and are located in chloroplasts within the cell. Carotenoids are yellow, orange or red and are located in chromoplasts within the cells. Anthocyanins are red, blue or purple and are located in the vacuoles in the cell. As apples mature, chlorophyll is degraded and carotenoids increase as chloroplasts transition to chromoplasts. At the same time anthocyanins may increase up to 5 fold. The apple skin has two types of cells: the epidermis is 2 or 3 cells deep and under the epidermis there are 6 to 10 hypodermis cells. The redness of the skin depends on the proportion of these cells containing anthocyanin.

Please have a look this review papers

1. Espley RV, Hellens RP, Putterill J, Stevenson DE, Kutty-Amma S, Allan AC. Red colouration in apple fruit is due to the activity of the MYB transcription factor, MdMYB10. The Plant Journal . 2007;49(3):414-427. doi:10.1111/j.1365-313X.2006.02964.x.

2. Jane E Lancaster,1 Jan E. Grant1 , and Carolyn E. Lister .Skin Color in Apples—Influence of Copigmentation and Plastid Pigments on Shade and Darkness of Red Color in Five Genotypes.J. AMER. SOC. HORT. SCI. 119(1):63-69. 1994.

3. APPLE SKIN COLOUR CHANGES DURING HARVEST AS AN INDICATOR OF MATURITY Grzegorz àysiak , Robert Kurlus , Zofia Zydlik , Dorota Walkowiak-Tomczak. Acta Sci. Pol., Hortorum Cultus 13(3) 2014, 71-83

4. Colour change of apple as a result of storage, shelf-life, and bruising. B. Dobrzañski, jr. and R. Rybczyñski. Int. Agrophysics, 2002, 16, 261–268

Thank you so much Dr. Sarhat for your information. Changes in color and brownness of the skin have occurred during storage in the refrigerator, and so far I have not seen this phenomenon.

hello:

I will send some publications that are related to pears but it can help you in some way.

you can also try Lancaster etal

Dussi, M.C., M. Huysamer. 1995. Severe postharvest summer pruning of mature ‘Forelle’ pear trees influences canopy light distribution, and fruit and spur leaf characteristics in the following season. Journal of the Southern African Society for Horticultural Sciences 5 (2) 57-60.

Dussi, M.C., D. Sugar, R.E. Wrolstad. 1995. Characterization and quantification of anthocyanins in red pears and the effect of light quality on fruit color. J. Amer. Soc. Hort. Sci. 120(5):785-789.

Dussi, C., D. Sugar, T. Righetti, and A. Azarenko. 1997. Effects of cooling by overtree sprinkler irrigation on fruit color and firmness in ‘Sensation' Red Bartlett pear. HortTechnology 7:55-57.

I agree with all, but which temperature you put the apples and how much take last in the refrigerator? I think it may be because of electrolyte leakage.

Dear Ahmad

Thanks for your interest in this topic. Since the apples were taken out of the market, I have not known the harvest time and storage in the cold store. But the skin color changes occurred after a few days in the refrigerator (4 °C).

Since the apples harvested normally, lasted 7 month approximately, because of this senescence has occurred. In other hand, keeping in refrigerator impelemetary helped that.

Dear Seied,

This is typical disorders of Red delicious - superficial scald.

a-farnesan oxidation in skin of apples is reason which causes this disorder as theoretical background.

However, There could be a several practical reasons:

1. Not proper temperature in cold storage - should be not more than +1 C,

2. Store over ripening fruits (more likely)

3. Storage is more than 6-8 month (each cultivar has storage ability threshold time )

4. Not proper ventilation - too much Ethylen and CO2 during storage

5. A lot evidences - over fertilizing by nitrogen of apple trees

Solutions to avoid in for future cases:

1. Strict temperature control during storage

2. Proper harvest time according of starch indexes

3. DPA treatment - This is very good solution

4. Calcium spray 2 times before of harvest.

hope this information will helps you.

if you need more particular information on storage please let me know.

Best regards.

Zviad Bobokashvili

Dear Dr. Bobokashvili

Thank you for your valuable answer.

Dear Seied Mehdi Miri,

I agree with answers of scientists, basically browning is associated with reaction of poly phenol oxidase (PPO) enzyme when apples are sliced or injured so PPO enzyme is oxidized results in browning. In second case mishandling of fruits will results in ethylene action and fruit senescence.