Key to delicious tree fruit is keeping it out of the killing zone

[Guest guest]

" Peach, plum and nectarine consumption has remained static in the United

States the past 20 years, despite repeated recommendations from the

federal government and the medical industry to eat more fruit for better

health. Surveys by researchers and the tree fruit industry have pinned

the lack of sales growth to negative experiences with fresh fruit, such

as lack of flavor, off flavor, flesh mealiness, dry fruit and flesh

browning. " --This resonated with me. I've quit buying a number of

grocery-store fruits due to its poor taste and quality. - ne

Key to delicious tree fruit is keeping it out of the killing zone

The fond memories of delicious peaches just plucked from a backyard tree

or purchased at a roadside stand can now be relived with fruit picked up

at the neighborhood grocery store. The key to great-tasting fruit with a

pleasing texture, according to a UC scientist based at the Kearney

Research and Extension Center near Parlier, is in the way it is handled

after harvest.

As long as anyone can remember, peach, plum and nectarine producers have

tried to cool their fruit down as quickly as possible after picking, and

keep it cool until it was placed in a grocery store display. But UC

postharvest physiologist Crisosto discovered that the practice

was subjecting fruit to what he calls the “killing temperature zone.”

Years of work in the state-of-the-art Gordon F. Postharvest

Laboratory, established in 1992 at Kearney, has resulted in a completely

new protocol for peaches, plums and nectarines as they journey from the

farm, to packing sheds, in the backs of trucks to distribution centers

and finally to the supermarket produce aisle.

“This has rocked our world,” said Mike Thurlow, the sales manager for

Mountain View Fruit in ley, whose company used to pick, pack and

ship as quickly as possible. “For us to pick our fruit and delay the

cooling, fiddle around with humidity, pressure and brix, then ship it

two, three or four days later, ready to eat – that is totally opposite

to what we had been doing.” (Brix is a measurement used by the food

industry to estimate the amount of sugar in fruit.)

Even though it was hard to accept at first, the packing houses have

learned that the new protocol – for which Crisosto has coined the term

“preconditioned” – results in better tasting fruit, and subsequently,

better sales of this Central California summertime staple.

“Preconditioned fruit is like the fruit you remember eating as a kid

when you went into your backyard and picked a peach off a tree,” Thurlow

said. “We are now able to commercially ship fruit that in years past you

could’ve only bought at a farmers’ market.”

Fresh peaches, plums and nectarines represent an important part of the

California agricultural industry, with crop production valued at $250

million in 2004. The state supplies fresh fruit to every state in the

nation and several countries overseas. California produces more than 90

percent of the nectarines and plums in the United States and provides

about 60 percent of the peaches. The earliest California tree fruit are

harvested in mid- to late-May, but the bulk comes off trees in June,

July and August. A few California fruit are still being picked as late

as October.

Peach, plum and nectarine consumption has remained static in the United

States the past 20 years, despite repeated recommendations from the

federal government and the medical industry to eat more fruit for better

health. Surveys by researchers and the tree fruit industry have pinned

the lack of sales growth to negative experiences with fresh fruit, such

as lack of flavor, off flavor, flesh mealiness, dry fruit and flesh

browning.

“After biting into a mealy or off-flavor peach, consumers won’t likely

buy any more,” Crisosto said. “We can improve the eating experience by

carefully managing the peach’s journey from the farm to the consumer’s

palate. That expands and strengthens the market for fresh fruit.”

In the past, UC researchers recommended fruit be cooled immediately

after harvest and kept at 32 degrees during transportation and handling.

“The problem with that,” Crisosto said, “is that most of the facilities

for transportation, distribution and retail sales cannot hold fruit that

low. It just doesn’t work in the real world.”

As a result, fruit would be exposed to a temperature range of 36 to 50

degrees, the range he calls the “killing zone” because it halts ripening

and damages the fruit. Crisosto studied previous research, worked

closely with the industry and exposed fruit to a wide variety of

temperatures in five temperature- and humidity-controlled fruit storage

chambers. He found that, in general, if the fruit is held at 68 degrees

for about two days following harvest, until it reaches a specific level

of ripening measured by fruit firmness, and then cooled down, shelf life

can be extended seven to 15 days and, most importantly, the fruit would

be more consistently pleasing when it reached consumers’ mouths.

“It initially blew our minds to walk out into our ripening room and

smell fruit,” Thurlow said. “We’ve got a lot of money out there ripening.”

But soon packers and grocers realized that preconditioning produced a

better product. Grocery companies now offer premiums of $1 to $4 per box

of preconditioned fruit, compared to fruit that has been handled the old

way.

“It’s made a huge difference in the quality of the fruit we provide to

the consumer,” said Herb Kaprielian of Kaprielian Brothers Packing

Company in ley. “We are able to deliver fruit that is juicier and

more consistent in quality.”

A group of fruit packers, including Kaprielian Brothers, have pooled

resources and developed a brand for fruit that has been preconditioned

called “Ripe ‘N Ready.” According to Steve Kenfield, the manager of Ripe

‘N Ready, some grocery chains will stock only preconditioned fruit.

“Retailers take the heat for fruit not eating well,” Kenfield said.

“Retailers are looking to stop those complaints.”

More than 200 varieties of peaches, 200 varieties of plums and 175

varieties of nectarines are sold commercially from California – each

with its own harvest time, flavor and color. Crisosto has found that

each one also has its own specific needs in terms of postharvest storage

temperature and timing.

Identifying each variety’s needs will keep the industry and its research

partners at the University busy perfecting fruit handling protocols in

order raise consumers’ confidence in the peaches, plums and nectarines

they buy at stores.

“You can’t shame people to eat more healthy food,” Kenfield said. “They

have to enjoy it. We are working to fix the eating quality of fruit.”

Tips for handling the fruit once you have it at home

After purchasing fresh peaches, plums or nectarines at the grocery

store, do not eat them and do not put them in the refrigerator until

they are ripe.

The fruit looks nice in a basket or bowl on the countertop or table, or

it can be placed inside a paper bag. It is ripe when it smells sweet and

fruity and yields slightly to the touch. The fruit can then either be

eaten or placed in the refrigerator to be eaten in the next few days.

Putting fruit in the refrigerator before it is ripe exposes it to the

“killing zone,” temperatures between 36 and 50 degrees, which stops the

ripening process and ruins the fruit.

For more information, contact Crisosto at or

carlos@....

http://ucanr.org/?story=81