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An experimental fruit thinner studied at Kearney

Mechanical fruit thinner may prove to be a money-saving device for farmers.

UC researchers are experimenting with a variety of methods that will help farmers reduce the cost of fruit thinning. Peach, nectarine, plum and apple trees typically set a tremendous amount of fruit. The fruit must be thinned considerably to ensure adequate fruit size.

Since employing farmworkers for hand thinning is a major expense for farmers, researchers have been looking for a mechanical alternative.

One such machine being tested this spring is a “drum shaker,” which was recently shipped to the Kearney Agricultural Research and Extension Center from the USDA Agricultural Research Service’s Appalachian Fruit Research Station in West Virginia.

“We took the drum shaker out to several orchards,” said UC staff research associate Becky Phene, who works in collaboration with UC pomology specialist Scott Johnson. “In four locations, we tagged and labeled shoots, then ran the drum shaker through those rows.”

The researchers counted the fruit on the shoots before and after the drum shaker treatment.

“Our findings show a modest removal of fruit at 350 to 400 rpm,” Phene said.

The experiments have shown that a number of factors come into play when using the mechanical thinning device, such as tree structure, age and fruit size.

“The larger, sturdier scaffolds are harder to shake and suffer more shoot damage or shoot removal,” she said. “The younger, more flexible scaffolds appear more capable of reverberating the energy out to more shoots and shake off more fruit. Also, larger fruit tend to have a better removal rate.”

Posted on Thursday, April 14, 2011 at 1:57 PM

Mission Bells embrace springtime at HREC

Mission Bells (Fritillaria lanceolata) are one of the first springtime flowers to welcome the warm sunny days at HREC.  This particular wildflower, which is in the Lily family (Liliaceae) is sparsely scattered thoughout the oak woodland and chaparral habitats, usually in shady cool places.  This photo portrays one of the better "stands" found on HREC.

Posted on Thursday, April 14, 2011 at 8:34 AM
  • Author: Robert J Keiffer

Pacific Rattlesnakes are out now at HREC!

Pacific Rattlesnakes (Crotalus oreganus) are common at their denning sites right now.  I have a UC Davis researcher, herpetologist Dr. Brad Schaffer possibly interested in doing some research on them at HREC.

Posted on Wednesday, April 13, 2011 at 11:16 AM
  • Author: Robert J Keiffer

First Post

This is a blog about the Hopland Research and Extension Center.

Posted on Wednesday, April 13, 2011 at 8:53 AM

Mandarin taste testing underway at Kearney

Sue Collin.
Mandarins may look like little oranges, but scientists believe that their distinct attributes demand special treatment to maintain a fresh, juicy and tangy character.

“We think the flavor of mandarins declines much more rapidly than oranges,” said Sue Collin, a UC Riverside staff research associate who is based at the UC Kearney Agricultural Research and Extension Center in Parlier.

The way oranges are set out at the grocery store or on home counter tops could be trouble for the more delicate mandarin. And when mandarins make a six-week sea voyage to the Pacific Rim, will Asian consumers find the fruit acceptable?

In order to provide farmers, shippers and retailers accurate information about the impact of different storage temperatures on the quality of the fruit, Collin is working with UC Riverside sub-tropical horticulturalist Mary Lu Arpaia and USDA plant physiologist Dave Obenland to understand the changes in mandarins stored at a variety of temperatures, at different humidity levels, for various periods of time.

“A grocery store may be holding fruit at room temperature, 68 degrees or even warmer,” Collin said. “We’re comparing fruit that has been stored in very controlled atmospheres – at temperatures in the 40s, 50s and 60s.”

When it comes to understanding the acceptability of fresh fruit, nothing can match the human palette.

Collin recruits staff based at Kearney to take a break from their jobs to come to a laboratory built at the agricultural research station specifically for sensory testing. The 1,100-square-foot laboratory features neutral white paint and broad-spectrum lighting. The ventilation system was designed to minimize distracting odors. Inside, six tasting booths each have small windows that open to the kitchen area, where samples are prepared.

“We do quite a bit of testing to see if our volunteers can tell the difference in fruit stored at different temperatures,” Collin said.

In conjunction with the human testing, Obenland studies the fruit’s chemical composition to find out if objective numerical values correlate with the more subjective findings of the human tasters.

Although the optimal storage temperature for mandarins is still under investigation, Collin suggested consumers should keep their mandarins in the refrigerator at home for best results.

“I think the flavor holds better and the fruit lasts longer in the refrigerator,” Collin said.

This research is being funded in part by the Citrus Research Board.

Posted on Tuesday, April 12, 2011 at 11:51 AM
Tags: mandarins (1), sensory testing (1)

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