Transcript Harvesting and Storing Fresh Vegetables

Harvesting and Storing
Fresh Produce
Jean F. Austin
Family and Consumer Science Educator
Maryland Cooperative Extension
It is the policy of Maryland Cooperative Extension that no person shall be subjected to
discrimination on the grounds or race, color, sex, religion, disability, age or national origin.
Today’s
Program
• A little food science – What
causes deterioration in fresh
produce?
• A little food history – How and
why we preserve food.
• A little nutrition – The
importance of vegetables to diet
and health.
• Not too much gardening advice!
Harvesting Garden
Produce: Sources
• Your home garden (or your
neighbors!)
• Local farmers’ market and farm
stands
• Pick Your Our (PYO) farmers
markets
• CSA – Community Supported
Agriculture
Harvesting Garden
Produce: WHEN?
• Days to maturity as a general
guideline
• Temperature, daylight hours,
rainfall, variety and soil
conditions all affect maturity
• Harvest in the cool morning
hours
• Don’t harvest after a heavy
rainfall
Harvesting Garden Produce:
HOW TO
• Hold the plants with one hand and
remove fruit with the other hand. Try
to avoid bruising
• Have the right tools and containers –
kitchen scissors, pruners or a sharp
knife and baskets or other containers
that permit ventilation
• Know your plants – some plants need
to be harvested to continue bearing.
What are the “maturity” or ripeness
indicators – color changes, height of
top growth, stem and flower
separation can all be indicators
Harvesting Garden
Produce: Guidelines
• Know how you plan to use the
vegetable – eat it, store it, preserve it
• Harvest only what you can use – a
meal’s worth or the “batch” you plan
to preserve
• Cool the vegetable to the appropriate
temperature as quickly as possible
after harvesting
• Store unwashed until just before
using
Harvesting Garden Produce:
Freshness
Color
Flavor
Smell
Texture
Appearance
Nutritional Value
Harvesting Garden Produce:
Nutrition
• Select locally grown, in-season
vegetables if possible
• Eat your vegetables as quickly
as possible after harvesting
• Cook your vegetables lightly.
Steam, microwave, stir fry, roast
are good techniques to preserve
taste and nutritional value
Harvesting Garden Produce:
Nutrition
• Season your vegetables with
low calorie sauces or fresh
herbs
• Variety in preparation and
recipes makes eating vegetables
more interesting and healthy
• Vegetables provide vitamins,
minerals, fiber and
phytochemicals (beta carotene,
lycopene) and very few calories
Harvesting Garden Produce:
Health
• Of all dietary factors associated
with cancer fruit and vegetable
consumption has the strongest
correlation as a protective factor
* National Institute of Health
• A 40% reduction in cancer rate
could be possible in the US if
we
- Exercise regularly
- Maintain a healthy weight
- Eat more fruits and vegetables
* American Institute for Cancer
Research
Harvesting Garden
Produce: Health
• Epidemological research
supports increased vegetable
consumption as beneficial:
- Decreasing risk of heart attack
and stroke
- Lowering blood pressure
- Avoiding diverticulitus
- Protecting against cataracts
and macular degeneration
* Willett Eat, Drink and Be Healthy
Harvesting Garden
Produce: Storage
How long does fresh produce
remain “fresh”?
• 3-4 days refrigerator storage is a
good “rule of thumb” for home
storage
• Timely harvest & proper storage =
Increased fresh quality
Harvesting Garden
Produce: Storage
What causes spoilage?
• Physical Damage – “Bruising” leads to
water loss, provides a place for microbial
growth
• Growth of microorganisms – molds,
yeast and bacteria
• Enzyme Activity (Enzymes are small
proteins in foods that start or help with
reactions, such as those that cause
browning, off-flavors, mushiness, etc.)
Harvesting Garden
Produce: Storage
• Goal is to avoid undesirable change
in plant tissue
- Stop or slow down metabolic
activity of the enzymes
- Stop or slow down microorganism
activity
Harvesting Garden
Produce: Storage
• Determine best temperature and
humidity level for storage.
Different vegetables need different
conditions (MN Fact Sheet)
- Cool and dry 50°-60° F 60%
humidity
- Cold and dry 32°-40° F 65%
humidity
- Cold and moist 32°-40° F 95%
humidity
Harvesting Garden
Produce: Storage
• Determine best temperature and
humidity level for storage (Idaho
Bulletin)
– Cold and moist
– Cool and moist
– Cool and dry
– Warm and moist
– Warm and dry
Harvesting Garden
Produce: Storage
• Microorganisms, especially
bacteria, are slowed by reduced
moisture and very low or very high
temperature. Bacteria thrive
between 40°-140° F 60% humidity
• Most bacteria grow best in a low
acid environment. (pH4.6 or >)
• Temperature, moisture and the acid
content of foods influence storage
potential.
Harvesting Garden
Produce: Preservation
Preservation Methods
Canning
Freezing
Preserving
Pickling
Drying
Smoking
Harvesting Garden
Produce: Preservation
• Food preservation methods are
a part of ethnic identity and
social development
• Preservation: extends
availability of foods, increases
available variety and decreases
food costs
• Drying is the earliest method
• Methods today include freezing,
pasteurization, irradiation and
ultra high temperature
packaging
Harvesting Garden
Produce: Preservation
• Preservation methods
manipulate the factors
considered for good storage.
• Acid content of food is
important in most preservation
methods.
• Heat, cold, sugar, salt, smoke,
vinegar and spices are used in
preservation
Harvesting Garden
Produce: Home
Canning Basics
•
•
•
•
•
•
•
•
•
Boiling Water Bath
Pressure Canner Processing
Acidity
Hot pack or raw pack
Proper Jars and Jar
Preparation
Recipe Selection
Headspace
Sealing the Jar
Storing Canned Foods
Harvesting Garden
Produce: Labels
• Name of product
• Added ingredients
• Form of food - halves,
whole, ground, etc.
• Packaging date
• Number of servings or
amount
9/15/02
Ground
Beef
1 pound
How Freezing Affects
Food
• To prevent color and flavor
changes, as well as loss of some
nutrients, enzymes should be
controlled.
• Enzymes in Vegetables
– Are destroyed by heat, called
blanching, before packaging
and freezing.
• Enzymes in Fruits
– Usually controlled by ascorbic
acid (also called vitamin C) or
some other additives.
– Fruits are usually not blanched,
but can be.
• People like them raw and
uncooked.
How Freezing Affects
Food --Rancidity
• Another natural change that
causes off-flavors,
particularly in fatty foods.
– Not a common problem in
fruits & veggies.
• Will continue to happen at
freezer temperatures, but
slower than at warmer temps.
• Best control is to keep as
much air out of the package
as possible.
Freezer Storage
What happens when the freezer is
above 0oF ?
Shelf life (storage time) for best
quality is shorter.
For same final quality:
Temperature
0o F.
5o F.
10o F.
15o F.
20o F.
25o F.
30o F.
Length of Storage
1 year
6 months
3 months
6 weeks
3 weeks
10 days
5 days
How Freezing Affects
Food
• Fluctuating Freezer
Temperatures
– Ice in food thaws a little and
then re-freezes.
– Ice crystals get bigger each time.
– Mushiness because large ice
crystal growth damages cells
more and more.
– Moisture pulled from product.
– Other quality losses speeded up
due to higher temperatures.
• Moisture Loss
– Freezer burn – tough and dry,
but safe.
Harvesting Garden
Produce: Preservation
• A 1999 nationwide survey by
CSREES researched home
canning activity
• 27% of households did some
home canning
• Tomatoes were the most
frequently canned food.
• Survey showed that many
households did not follow best
practices, putting people at risk
of food borne illnesses.
Additional Resources
• www.uga.edu/nchfp/index/html
CSREES supported website with
complete information.
• USDA Agriculture Information
Bulletin No.539 Complete Guide to
Home Canning September 1994
• Preserving Summer’s Bounty: A
Quick and Easy Guide to Freezing,
Canning, Preserving and Drying
What You Grow Rodale Press, 1998