Apple peel appeal: Using software to measure variances in 'honeycrisp' apple peels

Feb 17, 2009
Computer measures amount of blush or stripe in peel of "honeycrisp" apple. Photo by Adriana Telias

Apples have long been associated with good health, including lower risks of cancer and cardiovascular disease. Apples also contain anthocyanins, important antioxidants that give the peels their red coloring. Redness is one of the most important factors consumers consider when buying apples.

One variety of apple called 'Honeycrisp' has peel pigment that takes on one of two patterns—"striped" or "blushed." A single 'Honeycrisp' tree can produce both striped and blushed apples, a phenomenon unique to this variety. In terms of marketability, consumers in some regions prefer striped apples, while others prefer blushed, but overall redder is better.

Adriana Telias, Emily Hoover, and Diego Rother of the University of Minnesota published a research study in the American Society for Horticultural Science journal HortScience comparing the coloring of 'Honeycrisp' apples. From 2005 the team studied the fruit of trees grown from buds on branches with exclusively striped or blushed fruit. The apples were separated as either striped or blushed, and color and stripe intensity were measured, and then the fruits were photographed. The researchers developed color-analyzing software to automatically separate the apples from the background in the photos and measure statistics such as mean color in large areas of the fruit peel.

It was found that blushed trees produced more blushed fruit than striped trees. Likewise, the markings on striped fruit were more intense on striped trees than blushed trees.

Position on the tree may also be related to the pattern, as it was observed that northeast-facing branches produced 13% blushed fruit compared to only 6% on southwest-facing branches. Southwest branches also produced more intensely striped fruit than northeast branches. And, within clusters of fruit, the apples were more likely to have similar coloring.

Each year, blushed fruit was found to be redder than striped fruit. "Given that blushed fruit are redder than striped ones, the goal should be to increase blushed fruit production when target markets prefer redder fruit," stated the researchers. They added; "This may prove difficult given that even the top blushed-producing trees never yielded more than 50% blushed fruit over all 3 years."

Because higher crop loads were associated with lower percentage of blushed fruit, the study suggests regulating the crop load to increase the number of blushed fruits, and that growing trees from buds of blushed fruit branches, should result in higher blushed fruit yields. This is based on indications that both genetic and environmental factors affect peel pigmentation.

The software developed to evaluate peel color in the study is available for community use.

More information: The complete study and abstract are available on the ASHS HortScience electronic journal web site: hortsci.ashspublications.org/cgi/content/abstract/43/5/1441 .

Source: American Society for Horticultural Science

Explore further: English foxes safe for now as Cameron backs down

Related Stories

California farmers agree to drastically cut water use

29 minutes ago

California farmers who hold some of the state's strongest water rights avoided the threat of deep mandatory cuts when the state accepted their proposal to voluntarily reduce consumption by 25 percent amid ...

Apple may deliver ways to rev up the iPad, report says

39 minutes ago

MacRumors last month said that the latest numbers from market research firm IDC's Worldwide Quarterly Tablet Tracker revealed Apple stayed on as the largest vendor in a declining tablet market. The iPad ...

Recommended for you

Godwits are flexible... when they get the chance

2 hours ago

Black-tailed godwits are able to cope with unpredictable weather. This was revealed by a thorough analysis of the extraordinary spring of 2013 by ecologist Nathan Senner of the University of Groningen and ...

Rules aim to protect imperiled bird's habitat in 10 states

10 hours ago

Interior Secretary Sally Jewell revealed plans Thursday to preserve habitat in 10 Western states for an imperiled ground-dwelling bird, the federal government's biggest land-planning effort to date for conservation of a single ...

Understanding how cells follow electric fields

11 hours ago

Many living things can respond to electric fields, either moving or using them to detect prey or enemies. Weak electric fields may be important growth and development, and in wound healing: it's known that ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.