Apple Defects and Blemishes

Partidura en el caliz

裂果萼

Defect

Some fruit varieties are more prone to the calyx split. Field management, including irrigation, can affect development.

Dr. Chris Johnston, Manager, Applications Engineering, TOMRA Food

Cork spot

Defect

Bitter pit defects first present on the skin as sparse, light grey spots. They can develop into clusters of darker grey spots. Occasionally, they appear as one or two spots rather than a cluster of small spots.

Within the apple, brown tissue will appear within the white apple flesh.

Bitter pit is caused by an imbalance of minerals, such as an increased ratio of potassium and magnesium to calcium.

However, it can also be caused by climate, such as warm weather or moisture stress as the fruit matures. Some causes can also be the result of management: heaving pruning, early harvest, or excessive nitrogen fertilization can result in bitter pit.

The ‘Honeycrisp’ and ‘Cortland’ varieties of apples are very susceptible to bitter pit.

Dr. Chris Johnston, Manager, Applications Engineering, TOMRA Food

Stem pull

Fresh; old

Defect

Similar tostem split an opening (tear) in the stem bowel.

Stem tear is caused by mechanical damage in the stem area often due to picking.

Dr. Chris Johnston, Manager, Applications Engineering, TOMRA Food

Granizo

冰雹伤

Defect

Apples damaged by hail early in the season present with deep depressions that lead the fruit to be completely deformed. A late-season hail event will result in bruising.

Hail damage occurs in the field as the result of a hail storm.

Dr. Chris Johnston, Manager, Applications Engineering, TOMRA Food

Decay

Podrido/ Machucon

腐烂

Defect

Rot is typically caused by a fungi infection that occurs via skin damage.

Dr.Chris Johnston, Manager, Applications Engineering, TOMRA Food

果肉褐变

Defect(Internal)

Internal browning occurs in the fruit’s flesh, usually near the apple core. It is not detectable on the fruit skin with the exception of very severe cases.

Internal browning is very likely to be caused by CO2 damage that occurs in storage. In some cases, the apples were stored in space that was too cold. However, internal browning can also occur in the field among over mature or large fruit.

Some varieties (Fuji, Braeburn, Cox’s Orange Pippin, and Jonathan) are more vulnerable to internal browning.

Dr.Chris Johnston, Manager, Applications Engineering, TOMRA Food

Quemado de sol

晒伤

Sunburn necrosis; sunburn browning; photo-oxidative sunburn; delayed or storage sunburn

Blemish

Sunburn appears as brown lesions that occur on the skin of the apple.

Sunburn and its subcategories are caused by intense heat change, often from the sun. Sunburn occurs when fruit is picked or in bins in the field during high temperatures

Most of the juvenile fruitlets that develop lesions early in the season will slough off the tree before harvest. However, fruit can look free from blemishes when put into storage only to show signs of delayed or storage sunburn when removed from storage later in the year.

Dr. Chris Johnston, Manager, Applications Engineering, TOMRA Food

Russet stem

果梗绣

Blemish

Russeting presents as brown tissue on the skin of the apple. The tissue can appear in a pattern that mimics netting.

When russeting becomes very severe, it can cause cracks in the skim of the apple.

Russeting is most often caused by friction applied to the fruit in the field.

A stem bowl russet occurs when the stem rubs against the fruit as a result of wind.

A body russet might be the product of the friction caused by the apple rubbing against branches or other fruit.

However, other climate conditions can contribute. Periods of high humidity or colder temperatures during the early development of the fruit can cause russeting. Additionally, russeting is more likely in fruit treated with caustic pesticides formulated as emulsifiable concentrates.

Dr. Chris Johnston, Manager, Applications Engineering, TOMRA Food