storing cut flowers

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Proper Temperatures for Storing Cut Flowers By Brenda Ingram-Christian, eHow Contributor Rapid cooling and proper temperature are key to maintaining the vitality of newly cut flowers. Most cut flowers prefer temperatures at 32 to 33.8 degrees Fahrenheit, according to ba.ars.usda.gov, with a relative humidity of 95 to 99 percent. Pre-Cooling Flowers have high respiration rates which can cause them to dry out quickly. Getting your harvested flowers from field to storage as quickly as possible is key to their survival and longevity. Flowers that are packed quickly for shipment should be cooled prior to placing them in boxes or they should be placed in boxes with vents to allow cool air to reach them. Tropical Flowers Tropical flowers can be sensitive to cold storage and should be stored at 50 degrees Fahrenheit. If they become too chilled, you may notice leaf or petal darkening or drying out. Anthurium, bird of paradise, ginger, some orchids and a variety of foliage plants are sensitive to colder temperatures, according to ba.ars.usda.gov. Bulb Flowers Tulips, narcissus and hyacinths store best at 33 to 35 degrees Fahrenheit with a relative humidity of 90 percent or more, according to University of Massachusetts Amherst. They have a relatively short shelf life of three to seven days, dependent on the care that is given post harvest. Gladiolas can be stored dry for up to a week or stored in a floral preservative for up to two weeks at 36 to 40 F, according to Kansas State University. Roses Roses need to be stored at 33 to 35 degrees Fahrenheit or the blooms may not open, or they may experience a short vase life. Considerations Never store fruit in the same cooler with fresh cut flowers. Fruit, especially apples, produces ethylene gas which will cause cut flowers to age faster. What is the floral fridge temperature for flowers? Written by cassie damewood Florists rely on the quality and freshness of their flowers to build and maintain a loyal clientele. To ensure their supplies of cut flowers last as long as possible, their coolers and refrigerators must consistently be kept at precise temperatures.

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Page 1: Storing Cut Flowers

Proper Temperatures for Storing Cut Flowers

By Brenda Ingram-Christian, eHow Contributor

Rapid cooling and proper temperature are key to maintaining the vitality of newly cut

flowers. Most cut flowers prefer temperatures at 32 to 33.8 degrees Fahrenheit,

according to ba.ars.usda.gov, with a relative humidity of 95 to 99 percent.

Pre-Cooling

• Flowers have high respiration rates which can cause them to dry out quickly. Getting your

harvested flowers from field to storage as quickly as possible is key to their survival and

longevity. Flowers that are packed quickly for shipment should be cooled prior to placing

them in boxes or they should be placed in boxes with vents to allow cool air to reach them.

Tropical Flowers

• Tropical flowers can be sensitive to cold storage and should be stored at 50 degrees

Fahrenheit. If they become too chilled, you may notice leaf or petal darkening or drying out.

Anthurium, bird of paradise, ginger, some orchids and a variety of foliage plants are sensitive

to colder temperatures, according to ba.ars.usda.gov.

Bulb Flowers

• Tulips, narcissus and hyacinths store best at 33 to 35 degrees Fahrenheit with a relative

humidity of 90 percent or more, according to University of Massachusetts Amherst. They

have a relatively short shelf life of three to seven days, dependent on the care that is given

post harvest. Gladiolas can be stored dry for up to a week or stored in a floral preservative

for up to two weeks at 36 to 40 F, according to Kansas State University.

Roses

• Roses need to be stored at 33 to 35 degrees Fahrenheit or the blooms may not open, or they

may experience a short vase life.

Considerations

• Never store fruit in the same cooler with fresh cut flowers. Fruit, especially apples, produces

ethylene gas which will cause cut flowers to age faster.

What is the floral fridge temperature for flowers?

Written by cassie damewood

Florists rely on the quality and freshness of their flowers to build and maintain a loyal clientele. To

ensure their supplies of cut flowers last as long as possible, their coolers and refrigerators must

consistently be kept at precise temperatures.

Page 2: Storing Cut Flowers

Keeping flowers at the right temperature preserves their beauty.

Jupiterimages/BananaStock/Getty Images

Refrigerator Temperatures

A floral cooler or refrigerator's ideal temperature is between 1.11 and 2.22 degrees Celsius for cut

flowers in a hydrating solution, although many units hover at around 38F. Temperatures that

fluctuate 5 degrees plus or minus of 38F can destroy or shorten the lives of flowers. If the flowers

have been removed from the hydrating mixture and placed in a preservative emulsion, they store

best at a constant 34F.

Display Units

Fresh flowers in a display unit also keep best between 34 and 36 degrees Fahrenheit to prevent

drooping or lost blooms. The containers should be plastic as metal may alter the pH balance of the

water or alter the preservative qualities of additives.

Humidity Requirements

Besides controlled temperatures, the humidity of floral storage areas must be carefully controlled.

Storage and display units need humidity levels of 90 to 95 per cent. Flowers placed in preservatives

require a minimum humidity level of 80 per cent.

Flowering Potted Plants

• Bulbs as flowering potted plants—keys to increased longevity (1.99MB pdf)

• Commercial transport of flowering potted plants: keeping quality beyond the bench (30.45MB pdf)

• Deliver poinsettias the consumer will enjoy. (1.16MB pdf)

• Effect of Nitrogen and Sulfur Applications on Post Chrysanthemum Production and Postharvest

Performance. II Plant Growth Responses (24.68MB pdf)

• Effects of exogenous sucrose on carbohydrate levels, flower respiration and longevity of potted

miniature rose (Rosa hybrida) flowers during postproduction (7.33MB pdf)

• Effects of Production and Postproduction Factors on Longevity and Quality of Kalanchoe (3.47MB

pdf)

• Growing Longer Lasting Bedding Plants (6.22MB pdf)

• High Production Temperature Increases Postproduction Flower Longevity and Reduces Bud Drop of

Potted, Miniature Roses 'Meriutral' and 'Medianclar' (623KB pdf)

Page 3: Storing Cut Flowers

• How to Make Long-Lasting, Top Performers out of Your Pot mums (11.44MB pdf)

• Post-greenhouse longevity of rooting room bulbs as flowering potted plants (15MB pdf)

• Postproduction performance of potted rose under simulated transport and low irradiance levels

(2.50MB pdf)

• Information about cut flowers

http://hort.ufl.edu/flowerpostharvest/potted-pubs.shtml

Cut Flowers

• Español

• AFE Special Report: Identifying Long-Lasting Cut Carnation Varieties (38KB pdf)

• AFE Special Report: Identifying Long-Lasting Cut Rose Varieties (65KB pdf)

• AFE Special Report: Improving Postharvest Performance of Alstroemeria (114KB pdf)

• AFE Special Report: Preventing Ethylene Injury to Fresh Cut Flowers (42KB pdf)

• AFE Special Report: Preventing Leaf Yellowing of Cut Oriental Hybrid Lilies (48KB pdf)

• AFE Special Report: Storage Temperature Effects on Cut Rose Varieties (58KB pdf)

• AFE Special Report: Three C's of Success with Fresh Cut Flowers - Care

• AFE Special Report: Three C's of Success with Fresh Cut Flowers - Cleanliness

• AFE Special Report: Three C's of Success with Fresh Cut Flowers - Cooling

• Bacteria-Free "Solutions" (703KB pdf)

• Can't Take the Heat (2.96MB pdf)

• Chill Out! (666KB pdf)

• Cleanliness Counts (584KB pdf)

• Cut Flowers: Handle with Care - Delivering Quality Flowers in a Global Marketplace (2.63MB pdf)

• De-myth-tifying Cut Flower Care (1.67MB pdf)

• Ethylene Happens (1.57MB pdf)

• Ethylene Protection (2.38MB pdf)

• Freshness Test: Will Your Flowers Pass? (2.03MB pdf)

Page 4: Storing Cut Flowers

• Gas Poisoning (1.85MB pdf)

• Give a Little Floral TLC (2.20MB pdf)

• Good Cents Marketing (640KB pdf)

• Good Intentions (5.28MB pdf)

• How's the Water? (1.59MB pdf)

• In Search of Freshness (507KB pdf)

• Long Live the Flowers: How to Keep your Flowers Going and Going (2.22MB pdf)

• Make Your Roses Last (1.31MB pdf)

• Problem Flowers: Tips for Solving the Common Longevity Challenges of 10 Problem Botanicals

(1.82MB pdf)

• Rose Care 101 (601KB pdf)

• Summer Smarts (2.44MB pdf)

• The Big Chill (1.62MB pdf)

• The Flower "Care-athon" (1.22MB pdf)

• The Secret of Longer-lasting Flowers (1.06MB pdf)

• Think Spring! Bulb Flowers are Favorites in Spring, But Need a Little Extra Care (1.09MB pdf)

• Thirst Aid (2.25MB pdf)

• Drenched for Success (678KB pdf)

• Effects of retail hydration on water uptake and quality of "Madame DelBard" roses after long-term

transport (2.45MB pdf)

• Plotted flowering plant publications

http://hort.ufl.edu/flowerpostharvest/cut-pubs.shtml

In What Temperature Should Fresh Flowers Be?

By Jacob J. Wright, eHow Contributor

A bouquet of fresh cut flowers usually brings a smile to someone's face. Since these

flowers lost their natural water source once severed from the plant, clean and fresh

water maintains their beauty. Temperature also plays a central role in the longevity of

cut flowers. Cooler temperatures slow bud opening or decay of stem and petal tissues.

Too warm temperatures hasten flower decay and increase the need for stems to absorb

adequate water.

Transportation to Market

• Do not refrigerate tropical cut flowers or foliage stems.

Page 5: Storing Cut Flowers

Whether grown thousands of miles away or a few feet from your front door, fresh cut flowers

begin to deteriorate once cut from the mother plant. Harvest of flowers often occurs in cool,

morning temperatures when plant tissues are turgid with liquid. Buds are tightly closed in

anticipation of later opening. During long-distance transport, refrigeration between 33 and 40

degrees Fahrenheit prolongs shelf life of temperate-climate cut flowers like tulips, roses, lilies,

pussy willows, camellias and lilacs. Tropical flowers, such as heliconias, gardenias and

gingers, suffer at temperatures below 55 F, so slightly warmer reduced temperatures are

needed during transport.

Room Temperatures

• Lilacs last longer in cooler, spring-like conditions.

Once on display, cooler temperatures slow the opening and duration of petals in individual

flowers. Interior spaces between 65 and 72 F supply cool temperatures to prolong fresh cut

flower vase life. Avoid placing cut flowers in direct sunlight where infrared radiation heats up

flower petal tissues and increase their need to absorb water to remain firm and fresh looking.

Tropical flowers suffer when exposed to chilly drafts near exterior windows and doors.

Water Temperatures

• Roses appreciate cool water for longer vase life.

Cut flower stems need to be initially placed in clean, fresh water at 110 F, according to the

University of Minnesota Extension. The very warm water facilitates rapid movement of water

molecules upward into the flower stems and is referred to as hardening. Keep the flower

stems in the water and allow the water to cool naturally to room temperature. Temperate-

zone flowers appreciate a cooler water temperature alongside cooler room temperatures.

Tropical flowers need at least room temperature water or slightly warmer around 75 F, since

their plant tissues don't normally receive chilly water in their growing environments.

Longevity Tips

• If the cut flower species is naturally from a cool habitat or flowers in a cool season, keep

room and water temperatures as cool as you can to prolong the flower display. Avoid

refrigeration and chilly water conditions for flowers that come from plants native to tropical

regions. The use of commercial floral preservatives is better than homemade remedies,

according to Mary H. Meyer of the University of Minnesota Extension.

What Is the Floral Fridge Temperature for Flowers?

By Cassie Damewood, eHow Contributor

Page 6: Storing Cut Flowers

Florists rely on the quality and freshness of their flowers to build and maintain a loyal

clientele. To ensure their supplies of cut flowers last as long as possible, their coolers and

refrigerators must consistently be kept at precise temperatures.

Refrigerator Temperatures

• A floral cooler or refrigerator's ideal temperature is between 34 and 36 degrees Fahrenheit

for cut flowers in a hydrating solution, although many units hover at around 38 F.

Temperatures that fluctuate 5 degrees plus or minus of 38 F can destroy or shorten the lives

of flowers. If the flowers have been removed from the hydrating mixture and placed in a

preservative emulsion, they store best at a constant 34 F.

Display Units

• Fresh flowers in a display unit also keep best between 34 and 36 degrees Fahrenheit to

prevent drooping or lost blooms. The containers should be plastic as metal may alter the pH

balance of the water or alter the preservative qualities of additives.

Humidity Requirements

• Besides controlled temperatures, the humidity of floral storage areas must be carefully

controlled. Storage and display units need humidity levels of 90 to 95 percent. Flowers placed

in preservatives require a minimum humidity level of 80 percent.

How to Store Flowers in the Refrigerator

By Cameron Easey, eHow Contributor

How to Store Flowers in the Refrigerator(Photo: Jeffrey Chen/Demand Media)

Flowers or flower arrangements that are received as a gift or for a special occasion can be kept for

long periods if they are properly stored. The key to storing flowers is to slow down the flowers

development and water loss. One way to do this is by putting the flowers or arrangement in your

refrigerator. Just make sure that there is enough room.

Page 7: Storing Cut Flowers

(Photo: Jeffrey Chen/Demand Media)

Fill the flower vase about three-quarters full with water.

(Photo: Jeffrey Chen/Demand Media)

Place the flowers that you want to keep in the vase.

(Photo: Jeffrey Chen/Demand Media)

Check the temperature of your refrigerator and make sure that it is set at or below 40 degrees.

Page 8: Storing Cut Flowers

(Photo: Jeffrey Chen/Demand Media)

Clear an area in your refrigerator to set the vase of flowers. Make sure to remove any fruit because

they should not be stored with the flowers.

(Photo: Jeffrey Chen/Demand Media)

Place the vase with the flowers on a shelf in the refrigerator.

Keep the flowers in the refrigerator for at least six hours each night. This will allow enough time for

the flowers to absorb the water and will stay fresh longer.

Optimal Temperature for Storing Flowers

By Fiona Wood, eHow Contributor

Cut flowers need to be well-hydrated to last. They should be kept in a cool place, but the

water in their vase right after they are cut should be warm.

Right after Cutting

• Flowers absorb warm water better than they absorb cool water. To ensure maximum

hydration, place them in a vase filled with water that is about 110 degrees Fahrenheit, about

the temperature of bath water. Then place them somewhere cool for an hour or two.

Storage Temperature

• Storing flowers at about 35 degrees Fahrenheit will keep them fresh longest. Cool

temperatures minimize water loss and slow development. Any temperature above freezing

but below 40 or 50 degrees Fahrenheit will work well. If the flowers are being displayed in a

Page 9: Storing Cut Flowers

room warmer than that, putting them in the fridge or another cool place at night or whenever

they are not being displayed will prolong their vase life.

Other Considerations

• Storing flowers in a fridge full of fresh produce may decrease their vase life, as fruits and

vegetables release ethylene, a ripening hormone that speeds aging in flowers.

How Long Can Fresh Flowers Live Without Water?

By Sarah Polson, eHow Contributor

Fresh flower arrangements are often used to mark a special occasion, brighten

someone's day or to just brighten up a room. How long those flowers will last depends on

the type of flowers as well as on what you do to take care of them.

Longevity by Type

• The first factor to consider in determining how long fresh flower arrangements will last is the

type of flowers in the arrangement. According to Teleflora, some of the longest-lasting cut

flowers are carnations, mini carnations, Anthurium and Star of Bethlehem. These variations

can last 14 days or more.

Examples of how long other flower types will last are as follows:

7-14 days: aster, chrysanthemum, gladiolus, heather, Asiatic and Oriental lilies, tuberose,

wax flower

5-7 days: anemone, calla, delphinium, freesia, gerbera, rose, snapdragon, zinnia

3-5 days: cornflower, daffodil, iris, lilac, lily of the valley, peony, tulip

1-2 days: gardenia

When to Cut

• If you are cutting the fresh flowers yourself to create an arrangement, when you cut them

can make a difference in how long they will last. The best time to cut flowers from your

garden is in the morning or late evening hours when it is cooler. Flowers are also most

fragrant in the mornings and filled with stored food.

Maturity

• The stage of maturity a flower is in can affect how long it will last after being cut. It's best to

cut flowers such as roses, daffodils, irises and gladiolas when they are still in the bud stage.

The flowers will then open and mature while in your flower arrangement.

Flowers such as marigolds and delphiniums, on the other hand, should be fully open before

they are cut.

How to Cut

• Use a sharp, unserrated knife or a pair of gardening shears, cutting the stems at a slant, and

immediately place the stems in warm water. If you bought precut flowers, you'll still want to

recut the stems when you get them home to give them a fresh surface with which to draw in

water. For best results, cut the stems under water to keep them from forming air bubbles

that prevent the stems from drawing in water.

Page 10: Storing Cut Flowers

• You'll also need to cut off any excess foliage on the stem that will be submerged in the water.

This will prevent them from molding in the water and creating bacteria that will shorten the

life of your blooms.

Water

• Most flowers need to be in warm water to help them live longer. Flowers produced by bulbs,

such as tulips and daffodils, need cold water.

Change the water every couple of days. Completely empty out the vase and replace the

water in it for your flowers. This is also a good opportunity to cut another 2 centimeters off

the stems to give them a fresh surface to draw water.

Flower Food

• Most fresh-cut flowers from the store will come with a packet of floral preservatives. The

preservatives contain sugar to help feed the flower, an acid compound to help the water

move more easily up the stem of the flower, and a biocide to help kill bacteria in the water.

You can make your own floral preservative. One simple solution is 2 ounces of Listerine

mouthwash per gallon of water. Listerine has sugar plus bacteria-fighting elements and is

acidic. You can also use lemon-lime soda in the water, plus a little bleach to help kill bacteria.

Tips

• Keep fresh flowers out of direct sunlight. It's also best to keep them away from vents,

radiators, drafts and TV sets so they stay cool.

In the evenings, move the flowers to a cooler place or refrigerate them to help them last

longer.

Keep flowers away from fruit. Fruit gives off a chemical that will age flowers more quickly.

The differences between a floral cooler & a beverage cooler

Written by tatyana ivanov

Commercial coolers are used for a variety of different purposes, and to cool many different products.

Two common types of coolers are the floral cooler and the beverage cooler. Both of these types of

coolers can be seen in supermarkets and floral shops, and many also exist in back rooms for storage.

Floral and beverage coolers are used for different purposes, and so they have different cooling

systems.

Page 11: Storing Cut Flowers

Florists use coolers to keep their flowers fresh

Jupiterimages/liquidlibrary/Getty Images

Purpose

One of the main differences between a floral cooler and a beverage cooler is their purpose. Florists do

not use coolers to make their flowers cold, but rather because the cool air prevents the flowers from

wilting and keeps them fresh. Supermarkets and other stores use beverage coolers to provide a cold

product to consumers. Because of these different objectives, both types of coolers have different

cooling mechanisms and options to accommodate different products.

Cooling Mechanisms

Beverage coolers and floral coolers use cold air in different ways. Floral coolers use a regulated air

system that prevents the flowers from being damaged by the influx of air, while preventing them

from drying out. Similarly, floral coolers allow you to adjust the humidity to be between 80 to 95 per

cent inside the cooler, which also helps prevent drying. Beverage coolers are designed to keep

beverages as cool as possible without freezing, and generally try to keep the humidity as low as

possible. Additionally, floral cooler thermostats are usually set lower than beverage cooler

thermostats.

Types of Coolers

Floral and beverage coolers come in a variety of models with different features. Both types of coolers

are made in walk-in and reach-in styles. The walk-in models are much larger and are meant to be

used more for storage than for product display. The reach-in coolers come with different door

options, including a sliding door and a door that you pull open. Either type of cooler can be custom

made to accommodate a specific space. Beverage coolers, however, come in an additional model that

is not available in floral coolers; the commercial beer cooler opens from a sliding door on the top.

Considerations

Though there are several companies that can convert a beverage cooler into a floral cooler, these

conversions can be more costly than purchasing a cooler than has been manufactured for flowers.

Determine how much stock you will be storing in your beverage or floral cooler before purchasing it,

so that you know what size cooler to get. Additionally, both floral and beverage coolers come with

different shelving options. Beverage coolers generally have more shelves placed closer together to

accommodate as much product as possible, while floral coolers have more spacious shelves to

prevent damage to the flowers.

Page 12: Storing Cut Flowers

Commercial Cooling of Fruits, Vegetables, and Flowers

Publication Number: 21567

Author: JAMES THOMPSON

Inventory Type: Paperback

Language: English

ISBN-13: 978-1-60107-619-9

Copyright Date: Rev. 2008

Length: 61 pp.

Challenges in Postharvest Handling of Cool Season Vegetables

Marita Cantwell

(Dept. Plant Sciences, University of California, Davis, CA 95616,Tel: 530-752-7305;email:

[email protected]; Webpage: http://postharvest.ucdavis.edu)

Abstract:This paper is an overview of important postharvest challenges facing handlers and

marketers of cool season vegetable crops from a California perspective. Consumers are increasingly

concerned about microbial food safety. Recent outbreaks of food pathogens on leafy greens and

other vegetables have focused much attention on food safety. The implementation of GAPs (good

agricultural practices) and GMPs (good manufacturing practices) is necessary to ensure safe products.

Many buyers require third party certification of compliance with good practices. There is increased

focus on temperature management and strengthening weak links in the cold chain. The most

effective way to ensure the quality and safety of vegetables is to maintain the cold chain after initial

cooling and provide as close to optimum storage/transport temperatures as possible. Other

environmental conditions that can significantly impact product shelf-life and quality include relative

humidity, presence of ethylene gas, and the composition of the atmosphere. Increased use of

modified atmospheres is another important trend in postharvest handling of vegetable products.

Atmospheres may be provided in consumer packages, in pallets shrouds, in storage rooms, or in

marine containers. The main benefits of modified atmospheres are to reduce rates of ripening and

senescence, to slow softening, to reduce decay, and possibly to reduce compatibility problems in

mixed load shipments. Ethylene contamination and its control remains another challenge. Molecular

modification of ethylene synthesis and perception sites in products, and the use of chemical blockers

of ethylene receptors are two strategies to reduce undesirable ethylene effects. In current

commercial handling, however, low temperature, ventilation and ethylene oxidation are the most

common practices to reduce ethylene concentrations. The increasing sophistication of packaging

materials, sanitation procedures, and emphasis on low temperature processing and handling have all

contributed to the success of fresh-cut products in the market place. Cool season fresh-cut vegetables

constitute the major volume of these products. Consumers want products with better sensory quality.

Although the diversity of products and presentations has increased, increased efficiency and

traceability during distribution are increasingly required by supermarket chains and food service

distributors.

Page 13: Storing Cut Flowers

Key words: Cool season vegetables; Postharvest handling ; Challenges

Introduction

In the U.S. fresh fruit and vegetable marketing system the focus is on adding value and

decreasing costs by streamlining distribution and understanding customer needs. This U.S. produce

marketing system has evolved toward increased direct sales from shippers to final buyers.

Consumers place high value on taste/flavor, freshness, and appearance of vegetables. Product form

and packaging are changing as more companies introduce value-added products like fresh-cut

produce, designed to respond to the growing demand for convenience in food preparation and

consumption. Fresh produce continues to be a critical element in the competitive strategy of retailers,

and year-round availability is now a necessity for both food service and retail. Key drivers in produce

marketing are global retail players, global retail brands, growing role of private labels, retailer-supplier

contracts/partnerships and the decline of the spot market.

Some of the challenges in postharvest handling of cool season vegetables to be briefly discussed

include ① increased concern over microbial food safety, ②better cold chain management of

perishables, ③role of modified atmospheres and ethylene, ④fresh-cut and value-added

products,⑤traceable and efficient handling during distribution.

1....Microbial Food Safety Considerations

Ensuring microbial food safety is the single most important challenge confronting the fresh

produce industry today, especially for cool season leafy vegetables that are eaten uncooked. Control

of decay causing fungal and bacterial microorganisms has been the main focus in the past, but

control of human pathogens (viral, parasitic and bacterial) now grabs the spotlight. Leafy vegetables

are produced in the “natural” environment, and therefore should be expected to carry a wide variety

of microorganisms. Most microorganisms on fresh produce are harmless, and the number of

organisms itself is not an indication of quality. Total counts of bacteria on freshly harvested

vegetables can vary from ten to millions of cells per gram of product, depending on environmental

factors. More important to food safety is the assurance that specific human pathogenic organisms

are not present. Concerns about the microbial food safety of fresh produce have been increasing

among consumers. One of many such efforts around the nation, a Center for Produce Safety was

founded in 2007 at UC Davis to serve as a clearinghouse for research and training on fresh produce

safety (http://cps.ucdavis.edu/).

The main strategy to ensure microbial food safety is to prevent contamination. In 1998 the FDA (US

Food and Drug Administration) issued a guidance document for the fresh produce industry (Table 1).

The goals of these guidelines are to reduce microbial risks by preventing contamination and by

improving the effectiveness of control measures when contamination exists. More recent documents

have been developed to add practical checklists to these general guidelines, such as the USDA Good

Agricultural Practices and Good Handling Practices Audit Verification Checklist

(http://www.fsis.usda.gov/). Other industry-government efforts have led to the development of

commodity specific guidelines (http://www.unitedfresh.org/newsviews/guidance_documents). After a

major food safety incident on spinach, leafy green vegetable growers in California developed a

marketing agreement which specifies metrics and verification processes to ensure microbial food

safety http://www.caleafygreens.ca.gov/ and this is now being proposed as the basis of a national

program (http://www.nlgma.org/).

Page 14: Storing Cut Flowers

An example of changing postharvest practices is the use of water. Water in dump tanks, water

flumes and recycled cooling operations is particularly susceptible to cross-contamination by decay-

causing organisms and/or microorganisms that cause food borne illness. Some of the organisms of

current concern include bacteria (E. coli strains, Salmonella spp., Listeria monocytogenes), protozoan

parasites (Cryptosporidium spp., Cyclospora spp.) and viruses (Hepatitis A, Norwalk virus). The main

purpose of sanitizers in water used in postharvest handling operations is to reduce microbial

contamination of the water and prevent cross contamination. Disinfectants do not eliminate

organisms from fresh produce. Typically, chlorinated wash water reduces microbial populations of

fresh fruits and vegetables by less than 100-fold. Most of the water sanitation in California is based

on the use of chlorinated disinfectants. Other alternatives are being actively evaluated including

ozone, chlorine dioxide, acidified sodium chlorite, ionization, UV and other types of irradiation,

hydrogen peroxide, and peroxyacetic acid.

Table 1....Brief summary of the main principles described in the FDA guide to minimize microbial food

safety hazards for fresh fruits and vegetables and elaborated on in subsequent guidelines

Postharvest step Principle emphasized

General Prevention of microbial contamination of fresh produce is favored over reliance

on corrective actions once contamination has occurred. Accountability at all

levels of the agricultural and packing operations is important to a successful food

safety program

Water Wherever water comes into contact with fresh produce, its quality dictates the

potential for pathogen contamination.

Manure & biosolids Properly treated manure or biosolids can be an effective and safe fertilizer.

Animal feces While not possible to exclude all animal life from fresh produce production areas,

many field programs include elements to protect crops from animal damage.

Worker health,

hygiene

Infected employees who work with fresh produce increase the risk of

transmitting food- borne illness.

Field sanitation Fresh produce may become contaminated during pre-harvest and harvest

activities from contact with soil, fertilizers, water, workers, and harvesting

equipment.

Packing facility Maintain packing facilities in good condition to reduce the potential for microbial

contamination.

Transportation Proper transport of fresh produce will help reduce the potential for

contamination.

Traceback The ability to identify the source of a product can serve as an important

complement to

good agricultural and management practices.

Page 15: Storing Cut Flowers

Verification Once good agricultural and management practices are in place, ensure that the

process

is working correctly.

2. Strengthening weak links in the cold chain

The most effective way to maintain the quality and safety of fresh fruits and vegetables is to

maintain the cold chain and provide as close to optimum storage temperatures as possible. Table 2

summarizes the cold chain for fresh fruits and vegetables and requirements for successful movement

from field to fork. Cool the product as soon as possible after harvest. Temperature is the most

important factor determining deterioration rate. Decreasing the temperature reduces the product’s

metabolism (respiration and ethylene production), water loss, and the growth of decay-causing fungi

and bacteria. Mechanical refrigeration is the basis for most cooling methods. Room cooling (placing

products in a refrigerated room) is a relatively low cost, but also slow method. The cold air needs to

circulate around the product to remove heat, so leave space between boxes and between pallets.

Forced-air cooling pulls the cold air through the containers and greatly increases the rate of cooling.

A cold room can be modified with portable and fixed forced-air handlers to increase cooling rates.

Hydrocooling (by submersion or spraying cold water) products that tolerate wetting provides fast

cooling and avoids water loss. It takes more time to hydrocool packed product and wood or waxed

containers are needed. Sanitation of the hydrocooling water (usually by chlorination) is critical to

prevent contamination. Some products tolerate contact with ice; crushed or flaked ice can be applied

directly or as slurry in water. Evaporative cooling can be used in hot dry environments by pulling

outside air through wet pads to provide high humidity, cooler air. Other environmental conditions

affect shelf-life (relative humidity, ethylene, and atmosphere composition), but these factors are less

important than temperature control and all are influenced by storage temperature.

Freshness is a very important quality attribute. Freshness can be maintained by expedited

marketing, but can also be achieved by storing for short periods (days) under the proper conditions.

The longer the period from harvest to consumption, the greater the emphasis on good temperature

management. The importance of temperature and prompt cooling are clearly shown in the case of

broccoli shelf-life (Figure 1). If products are stored for long periods (weeks), they need to be kept

very close to their ideal storage conditions to minimize quality loss. Once the product has been

cooled, low rates of air circulation reduce water loss during storage. Cool season vegetables require

high humidity during storage to prevent dehydration. All cool season vegetables (Brassicas, lettuces,

celery, carrots, etc) are non-chilling sensitive products with recommended storage temperatures of 0-

3°C). Chilling-sensitive vegetables (recommended temperatures vary from 7-13°C) include basil,

cucumbers, eggplants, tomatoes, peppers. A listing of specific temperature and storage

recommendations for many fruits and vegetables can be found at

http://postharvest.ucdavis.edu/Produce/Storage/index.shtml. Postharvest treatments and

technologies other than temperature management (plastic packaging, humidity control, ethylene

control, modified atmospheres, decay-control treatments) are considered supplemental to this

fundamental technology. Although marketing requirements are changing for fresh produce, the

implementation of basic postharvest principles remains relevant to all fresh produce (Table 3).

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Figure 1. Impact of temperature (left) and cooling delays (right) on shelf-life of broccoli

Table 2. Maintaining the cold chain for perishable fruits and vegetables

Postharvest operation Temperature Requirements

Harvest Protect the product from the sun

Transport quickly to the packinghouse

Cooling Minimize delays before cooling

Cool the product thoroughly as soon as possible

Temporary storage Store the product at optimum temperature

Practice first-in first-out rotation

Ship to market as soon as possible

Transport to market/distributor Use refrigerated loading area

Cool truck before loading

Load pallets towards the center of the truck

Put insulating strips inside door or reefer if truck makes multiple stops

Avoid delays during transport

Monitor product temperature during transport

Handling at distribution Use a refrigerated unloading area

Measure product temperature

More product quickly to the proper storage area

Transport to retail or foodservice operations in refrigerated trucks

Display at proper temperature range

Handling at home or Store product at proper temperature

Foodservice outlet Use the product as soon as possible

Table 3....Ten important guidelines for postharvest handling of cool season vegetables

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1. MATURITY. Harvest the product at the correct stage of maturity.

2. REDUCE INJURIES. Reduce the physical handling to a minimum; every time product is handled,

it is damaged.

3. PROTECT PRODUCT. Protect the harvested product from the sun; bring it rapidly from the

field/exposed area to the packing station and keep out of the direct sun. Transport carefully

4. CLEANLINESS & SANITATION. Keep the packing line as simple as possible and keep it clean.

If water is used, use clean water or a sanitizer if the water is reused. Maintain strict worker

hygiene. Comply with guidelines for GAPs (Good Agricultural Practices) and GHPs (Good Handling

Practices).

5. PACK CAREFULLY. Sort, classify and pack the product carefully to achieve uniformity and to prevent

damage (compression, scrapes, etc.) which causes decay and inferior quality; use an adequate box or

container. Packaging can also be informative.

6. PALLETIZE. Insure that the boxes are well aligned on the pallet and that the pallet is strapped.

7. COOL. Cool the product as soon as possible after harvest; generally for every hour of delay from

harvest to initiate cooling, one day of shelf-life is lost. Lowering product temperature is the most important

way to reduce deterioration.

8. KNOW PRODUCT. Know the requirements of the market (size, maturity, etc) and the product

handling requirements (temp., RH, shelf-life, etc.) of the product.

9. COORDINATION. Always try to coordinate the postharvest handling so that it is efficient and rapid.

Postharvest handling maintains the quality of a product, it can not improve it.

10. TRAINING and COMPENSATION. Train and compensate well the workers involved in critical

postharvest handling steps; make sure that workers have the necessary tools to facilitate their

work

3. Modified atmospheres and ethylene

Modification of the atmosphere typically involves lowering the oxygen and raising the carbon

dioxide concentrations in the atmosphere surrounding a product. Normal air is comprised of about

78% nitrogen, 21% oxygen, 0.03% carbon dioxide and other inert gases. Sometimes removal of

ethylene is also considered in modified atmospheres. The term controlled atmosphere is used when

the atmosphere can be monitored and controlled, and the term modified atmosphere is used when

the atmosphere is different from normal air but there is no ability to control concentrations. The

latter includes the use of pallet shrouds with high carbon dioxide for decay control and plastic film

packaging for fresh-cut vegetables. Controlled and modified atmospheres are a supplement to

proper temperature and relative humidity and may offer several benefits: retard color and texture

changes, retard senescence and compositional changes in vegetables, reduce physiological disorders

such as chilling injury, retard decay growth, and control insects in stored products. Products differ in

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their tolerance to low oxygen and high carbon dioxide atmosphere medication and Table 4 provides

some examples. If atmospheres are outside these beneficial levels, products can be damaged. Most

of the information on CA/MA has been developed empirically. There is a need to better understand

the physiological effects of short-term and long-term CA. In the future, ‘sense and respond’

technologies may permit a more a tailored use of MA.

Table 4....Examples of the tolerance of vegetables to low oxygen and high carbon dioxide levels

Minimum oxygen concentration tolerated Maximum carbon dioxide concentration tolerated

% O2 Products % CO2 Products

0.5 salad-cut vegetables 2 tomato, pepper, lettuce, endive, Chinese

cabbage, celery, artichoke, sweetpotato

1.0 mushroom, garlic, onion, most

fresh-cut fruits and vegetables

5 peas, chile peppers, eggplant, cauliflower,

cabbage, radish, carrot

2.0 sweet corn, beans, celery, lettuce,

cabbage, cauliflower

10 cucumber, summer squash, snap bean,

okra, asparagus, broccoli, parsley, leek,

green onion, bulb onion, garlic, potato

3.0 broccoli, tomato, pepper,

cucumber, artichoke

15 sweet corn, mushroom, spinach, kale,

Swiss chard

5.0 green peas, asparagus, potato

Ethylene is a potent gaseous plant growth regulator that may affect many aspects of plant growth

and development. It is produced by all fruits and vegetables, and may have both beneficial and

detrimental impacts on fresh produce (Table 5). In climacteric fruits, ripening is regulated by ethylene

(bananas, avocado, mango, papaya, apple, tomato, etc) but ethylene has no or minimal affect on the

ripening process of non-climacteric fruits (strawberry, citrus, pepper). However for most leafy and root

vegetables, ethylene production rates are very low and these vegetables are damaged by ethylene in the

storage environment. There are 5 strategies to control ethylene: avoid, remove, inhibit production,

inhibit action, and modify plant response through genetics. Avoidance includes keeping ethylene

generating fruits away from sensitive vegetables, and keeping extraneous sources of ethylene such as

propane forklifts away from sensitive products. Removal techniques include ventilation with fresh air,

absorption of ethylene (with carbon filters for example), and oxidation of ethylene (permanganate and UV

scrubbers for example). Low temperature retards ethylene production by fruit and there are specific

inhibitors for enzymes of the ethylene biosynthesis pathway. Inhibition of ethylene action can be

achieved with low temperature, controlled atmospheres, and use of chemical inhibitors. Finally, genetic

or molecular engineering of specific enzymes has been very effective to control ethylene production and

ethylene action and this is used commercially in some flowers. Currently the most important of the

chemical inhibitors of ethylene action is 1-MCP (1-methylcyclopropane as it binds to the ethylene

receptors on cell membranes, rendering the product insensitive to ethylene.

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Table 5....Examples of consequences of ethylene action in fruits and vegetables

Beneficial effects Detrimental effects

1. Stimulates ripening of climacteric fruit 1. Accelerates senescence

2. Promotes color development in fruits 2. Causes excessive softening in some fruits

3. Promotes de-greening of citrus 3. Stimulates chlorophyll loss, yellowing

4. Stimulates dehiscence in nuts 4. Stimulates sprouting

5. Alters sex expression in Cucurbits 5. Promotes discoloration reactions and related disorders

6. Promotes flowering in pineapple 6. Promotes abscission of leaves and flowers

4. Increased Diversity of Value-added Products

The average number of items handled in a U.S. fresh produce department is over 300 today, up

from fewer than 140 twenty years ago. Yet six commodity groups still make up 42 percent of total

sales, just as they did in the 1980s: bananas, apples, citrus fruits, potatoes, lettuce, and tomatoes.

Part of the diversity in the U.S. supermarket is the result of diversity within basic produce categories,

as illustrated with lettuce: intact crisphead and loose leaf lettuces are packed into various size carton

and plastic boxes; lettuces are commonly marketed as cut salad products in different sizes for retail

and food service. Also there may be special types of the conventional items. Broccoli, for example,

has many “relatives” including gailan, rapini, purple broccoli, broccoflower, broccoli romanesco.

Diversity of produce is also seen currently in the offerings of products according to production

systems; conventional, organic, sustainable, or protected cultivation.

Fresh-cut or minimally processed or fresh-cut products have grown rapidly during the past few

years, extending from the foodservice sector to the retail shelf. Fresh-cut produce now represents

about 15% of the value (12-15 billion dollars) of fresh produce in U.S. supermarkets. Packaged salads

alone are valued at about 50% the total value of fresh-cut produce items. Fresh-cut products are

prepared and handled to maintain their fresh state while providing convenience to the user.

Producing minimally processed products involves cleaning, washing, trimming, coring, slicing,

shredding, and other related operations. There are many examples of fresh-cut products among the

vegetables: fresh salad mixes, cut green beans, broccoli and cauliflower florets, slaw mixes of

cabbage and carrots, celery and carrot sticks, sliced mushrooms, whole peeled and diced onions,

garlic, and potatoes. About 70% of the total volume of fresh-cut items is comprised of lettuce, green

cabbage, carrots, onions, potatoes, broccoli and cauliflower. These are typically expected to have a

shelf-life of 10-14 days. The other fresh-cut vegetables usually have less shelf-life (Cantwell, 2009).

The increasing sophistication of packaging materials, strict sanitation and concerns about microbial

contamination, and emphasis on low temperature processing and handling have all contributed to the

success of fresh-cut products in the market place (Table 6).

Throughout the 1990s a major industry debate existed over whether it was preferable to process

at the shipping point, where product freshness is at its maximum level, or at the destination, where

product reworking can occur. Both require optimal temperature management throughout distribution

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to maximize marketable product. It now appears evident that regional processing plants will

dominate, due to proximity to market and the demand for just-in-time deliveries. Although the fresh-

cut segment of the produce industry is relatively new, there has been an increase in industry

consolidation as this product category has matured. Currently, two California-based companies

control around 65 percent of total retail packaged salad sales. In some cases, California processors

have developed joint ventures with regional processors to expand distribution of their brands into

new geographic markets.

Table 6....Basic requirements for preparation of minimally processed fruits and vegetables

• High quality raw material: Variety selection; Production practices; Harvest and storage conditions

• Strict hygiene and good manufacturing practices: Use of HACCP principles; Sanitation of

processing line, product and workers

• Low temperatures during processing: Use of cold water flumes; Process room is refrigerated;

Process line shut down if product temperature exceeds 4°C

• Careful cleaning and/or washing before and after peeling: Good quality water (sensory, micro, pH)

• Use of mild processing aids in wash water for disinfection or prevention of browning and texture loss:

Chlorine, ozone, other disinfectants; antioxidant chemicals; calcium salts to reduce firmness loss.

• Minimize damage during peeling, cutting, slicing and/or shredding operations; Sharp knives on

cutters; elimination of defective and damaged pieces

• Removal of excess moisture: draining, spin or air drying; combination technologies

• Correct packaging materials and packaging methods: Selection of plastic films to ensure adequate

oxygen levels to avoid fermentation; selection of appropriate films for piece size and product type

• Correct temperature during distribution and handling: Keep all fresh-cut packaged products at 0-5°C

5. Packaging and traceable, efficient distribution

Although the diversity of products and presentations has increased, there is a trend to simplify

the excessive types of packaging in the U.S. In some distribution systems, plastic containers are

being used, but most vegetables are still marketed in carton boxes. Carton manufacturers have

developed a new carton with a common standard pallet ‘footprint’ of 16 x 24, but of varying heights

to accommodate a wide range of products, with interlocking tabs along the long side, and open retail

display-ready http://www.internationalpaper.com/PDF/PDFs_for_Packaging/CFSTechnicalManual.pdf.

Such a modular system for packing fresh produce was proposed many years ago by produce trade

associations working groups to reduce the plethora of packaging types used (>200). This packaging

is similar to the ‘Eurobox’ concept of interlocking, stacking, layered, standard modular corrugated

boxes designed specifically for produce. Supermarket chains are interested in reduced package types

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to permit implementation of mechanized selection systems at their produce distribution centers.

Changes in plastic or carton containers dimensions and volumes may affect cooling rates and require

changes in vent placement, pallet stacking patterns and cooler design and management.

Successful produce marketing firms will become more market-driven, identifying and meeting the

specific needs of each market segment for quality, packaging, product form, merchandising and

information. More produce marketing firms are adopting a supply chain management approach,

emphasizing faster delivery, more accurate temperature management, and improved packaging

technologies, all based on better demand information. Broader adoption of standardized PLU (Product

Look Up) codes and the introduction of more packaged produce items will permit better information

management through EDI (Electronic data interchange) and category management. More recently

RFID (Radio frequency identification) technology allows for identification of a package from the field

through the entire marketing system and allows for complete traceability. However, there are some

technical challenges with RFID use on high water content perishable products and current costs for

implementation are considerable high. Other approaches include the Global Trade Item Number

(GTIN) for external traceability. http://www.unitedfresh.org/newsviews/produce_traceability_initiative

Specific information exists for postharvest handling requirements of many specific products.

Many produce handlers, however, do not have a good understanding of the interaction between the

handling steps or are unable to integrate the entire handling system to make management decisions.

Certainly, ensuring microbial food safety requires an integrated approach to the postharvest value

chain. Unnecessary delays are particularly troublesome for more perishable leafy greens and for

packaged fresh-cut products. An example of the increased need for integration and logistics of

perishable handling is emphasized by the World Food Logistics Organization (www.wflo.org), which

developed from the previous Refrigeration Research and Education Foundation. Their focus is on

perishable warehousing, transportation, distribution, information and logistics. “Food miles” is a

recent environmental issue that concerns the costs to transport fresh produce from source of

production to the consumer and is one reason for ‘buy local, buy fresh’ campaigns

(http://attra.ncat.org/farm_energy/food_miles.html). And more generally, concerns over sustainability

(environmental, social, and economic) have impacted all segments of the fresh produce industry.

References

Cantwell, M. (editor compiler). 2009. Fresh-cut Products: Maintaining Quality and Safety. Postharvest

Horticulture Series No. 10. UC Postharvest Research & Information Center,

http://postharvest.ucdavis.edu.

Cook, R. 2008. The dynamic U.S. fresh produce industry: an industry in transition.

http://postharvest.ucdavis.edu/datastorefiles/234-1124.pdf.

FDA. 2007. Guide to Minimize Microbial Food Safety Hazards of Fresh-cut Fruits and Vegetables.

http://www.cfsan.fda.gov/~dms/prodgui3.html.

Gorny, J.R. (ed.). 2001. Food Safety Guidelines for the Fresh-cut Produce Industry. 4th edition. 216pp.

United Fresh Produce Association. http://www2.unitedfresh.org.

Gorny, J.R. (ed.). 2003. Packaging Design for Fresh-cut Produce. 122pp. United Fresh Produce

Association.

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http://www2.unitedfresh.org.

Gross, K.C., C.Y. Wang, and M. Saltveit. 2004. The Commercial Storage of Fruits, Vegetables, and Florist

and Nursery Crops. U.S. D.A. Agriculture Handbook 66. http://www.ba.ars.usda.gov/hb66/.

Kader, A.A. (ed.). 2002. Postharvest Technology of Horticultural Crops. Univ. CA Div. Agr. Natl. Res.

Publication #3311. 535 pp. http://postharvest.ucdavis.edu.

Produce Marketing Association. 2009. PMA consumer research on food safety and sustainability.

http://www.pma.com/issues/sustainabilityresearch.cfm.

Shewfelt, R.L., B. Brückner (eds.). 2000. Fruit and Vegetable Quality. Technomic Publ. Inc., 330 pp.

Suslow, T.V. 1998. Postharvest Chlorination- Basic Properties. UC Div. Agr. Natl. Resources Publication

8003. 8 pp. http://ucgaps.ucdavis.edu/documents/newsletter537.htm.

Suslow, T.V. 2007. Postharvest handling for organic crops. UC Div. Agr. Natl. Resources Publ. 7254. 8 pp.

http://anrcatalog.ucdavis.edu/; http://ucgaps.ucdavis.edu/documents/newsletter611.htm.

The Packer. Weekly newspaper for the produce industry. www.thepacker.com.

Thompson, J.F., F.G. Mitchell, T.R. Rumsey, R.F. Kasmire and C.H. Crisosto. 2001. Commercial Cooling of

Fruits, Vegetables and Flowers. Univ. Calif. ANR Publ #21567. 61 pp. http://postharvest.ucdavis.edu/.

University of California Postharvest Website: http://postharvest.ucdavis.edu/.

University of California Good Agricultural Practices website: http://ucgaps.ucdavis.edu.

University of California Food Safety website: http://www.ucfoodsafety.ucdavis.edu/.

USDA. 2007. USDA Good Agricultural Practices and Good Handling Practices Audit Verification

Checklist” http://www.ams.usda.gov/fv/fsis/GAP%20&%20GHP%20Checklist%20May%2007.pdf.

http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-1110/

http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-1120/

http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-1121/

http://ucce.ucdavis.edu/files/datastore/234-1901.pdf

http://ucce.ucdavis.edu/files/datastore/234-72.pdf