A brief view about preservation of Fruits and vegetables

1. Preservation Techniques
Lakshmi S
1913392048003

2. NEED FOR PRESERVATION
• To minimize pathogenic bacteria –
Food in long-term storage is at serious risk of spoilage due to bacteria such as E. coli, Salmonella, and
other pathogens. Bacteria only need warmth, moisture, and time to rapidly multiply in food, but
food preservation inhibits one or more of these conditions and stops their growth.
• To keep food at its best quality –
Food deteriorates over time due to spoilage. In many cases, mild spoilage doesn’t make food
unsafe to eat, but it significantly affects its taste, texture, and appearance. Proper food
preservation can help retain some of these qualities, as well as the nutritional value of certain
foods.
• To save money –
Waste is costly, both at home and in a commercial setting. Ideally, we should avoid
buying more than we can use, but various preservation methods, if done safely, help us
to keep vegetables, fruits, meat, etc. well past their usual expiration so there’s no need
to bin them.

3. METHODS
• Food preservation methods range from the simple process of chilling to more complex
procedures such as canning. Many are creative options in various forms of packaging also
helps to preserve food. Preservation helps to reduce waste and increase profit.
• Drying
• Freezing
• Preservation by heat
• Sugaring
• Salting
• Canning
• Vacuum Packing
• Addition of Chemicals

4. DRYING
• Drying is the removal of water content from fruits
and vegetables by exposing to the sunlight or any
other hot air.
• As this method removes water from biomaterials,
it is also called dehydration.
• After drying, the fruits and vegetables are exposed
to sulphur fumes which can maintain their original
colour and avoid spoilage by microbes.
DRYING PRESERVE FOODS SUCH AS:
• Dates, grapes, jack, peaches, beans, bitter gourd,
garlic, onion, potato, tapioca, etc. are preserved by
drying

5. FREEZING
• If stored properly, frozen food can last for months. In fact, because bacteria cannot grow
when frozen, food we keep in the freezer can remain safe to eat for almost indefinite periods
of time. However, it will eventually deteriorate in quality and become unappetizing, so we
should use most frozen food within a few months or a year.
TO SAFELY FREEZE FOOD:
• Set the freezer to a temperature between -18°C and -22°C.
• Place food in air-tight containers or freezer bags before freezing. Proper wrapping is
especially important for meat, otherwise it may get freezer burn and become inedible.
• Only freeze items before their best before or use by date.
• Never refreeze defrosted food, as it gives bacteria an opportunity to grow between thawing.
You should either use it right away or store it in the fridge for up to 24 hours.
• Defrost the freezer regularly to keep it free of an ice build-up. You should be able to keep
frozen food in the fridge for a couple of hours maximum while the freezer defrosts.
• Label food with the date you freeze it. You can refer back to the date to see whether you
should use the food before it deteriorates. Use our online guide to check how long food lasts
in the freezer.

6. SUGARING
• Preserving food in a high-sugar environment stops bacterial growth by
reducing the food’s water content. It works particularly well for fruit:
we can make jam and marmalade that lasts for a long time, and we can
use canning to store it.
• All sorts of sugary substances work well to preserve food, including
sugar granules, sugar syrup, or honey. Some sugaring recipes even use
alcohol alongside sugar to preserve certain foods.
SUGARING PRESERVE FOODS SUCH AS:
• FRUIT – apples, peaches, plums, apricots, cherries, and more preserve
well when sugared.
• VEGETABLES – ginger and carrot are commonly sugared and used for
relishes or condiments.
• CERTAIN FISH AND MEAT – you can combine sugar with salt or another
liquid to make a brine that helps preserve meat and reduce saltiness.
• Using an excessive amount of sugar comes with health risks, but if you
reduce the amount of sugar to lower than what is necessary, you may
allow the food to spoil. Make sure you follow suitable sugaring recipes
shared online or in books to get the right amount, and be sure to
consume sugared foods in moderation.

7. SALTING
• Similar to sugaring, salt draws water out of food and
stops bacterial growth. In high concentrations, it can
even destroy bacteria cells, although by this point
the food is likely unappetizing.
There are two forms of salting:
• Dry curing – you apply salt to the food, such as meat,
and leave it to draw out the water.
• Wet curing – better known as brine, you mix salt
with water and add food to the liquid to preserve it,
usually together with canning.
• As with sugar, excessive salt consumption can harm
health, so you should follow suitable salting recipes
found online or in published food preservation
books. You also need to use salt specifically designed
for pickling or a Kosher salt.

8. CANNING • Keeping food canned significantly extends its lifespan –
but only if done correctly. The canning process preserves
food by removing oxygen through an airtight seal and
containing food in an acidic, sugary, or salty environment,
where bacteria cannot thrive.
CANNING PROCESS:
• Select good quality food that is still within its best before or
use by date. Handle it hygienically.
• Purchase suitable jars and self-sealing lids specifically designed
for canning. You cannot reuse old peanut butter jars and jam
pots; they won’t ensure an airtight seal.
• Purchase a canning rack.
• Follow tested preservation recipes. You must follow every step
carefully to make sure your canned foods preserve safely.

9. CANNING
CANNING STEPS:
• Heat the jars beforehand in simmering water (not boiling).
• Prepare the food according to the preservation recipe. You usually need to heat food to boiling.
• Remove jars from the water and loosely fill them with the food.
• Depending on the recipe, you may fill the jar entirely with the food (e.g. jam) or you may need to
add an acidic liquid or brine, which you’ll boil beforehand.
• Leave ½ inch of headspace and apply the sealing lid. Adjust the lid until the fit is fingertip tight.
• Submerge the jars in boiling water using your canning rack for the period of time that the recipe
states.
• Remove and set aside to cool for as long as stated.
• It’s critical that you follow a tested canning process to increase the longevity and safety of food.

10. VACUUM PACKING
• Similar to canning, vacuum packing deprives bacteria of oxygen by creating an airtight atmosphere. While food may not last for as
long as canned goods, vacuuming still extends its storage life for much longer than keeping food in the fridge or in a cupboard.
• Vacuum packing also has value as a preservation method because it preserves the quality without the need for other
ingredients (unlike canning). It usually maintains the food’s smell, colour, taste, and texture – which is particularly desirable for
meat you intend to cook rare. In the absence of air, vacuum packed food also retains its moisture, which ensures optimum food
quality.
• Beyond preservation, vacuum packing also works well for food preparation. Many chefs vacuum pack specific ingredients and cook
it at a precise temperature to produce unique results.
TO SAFELY VACUUM PACK FOOD:
• Prepare the food hygienically. Wash fruits and vegetables and trim unwanted skin,
fat, and bone from meat.
• Place the food inside a suitable vacuum packing plastic bag.
• Feed the plastic bag into a vacuum packing machine.
• Allow the vacuum packing machine to run.
• Store in the fridge or a cool, dry place.

11. CHEMICAL PRESERVATION
• Chemical substance which can protect fruit or vegetable preparation from
microbial spoilage, are called preservative. Benzoic acid, potassium meta
bisuphite and sulphur di oxide are good preservatives for juices and other
liquids.
• Bezoic acid is used in the form of sodium benzoate. Nearly 0.06% sodium
benzoate is enough to protect fruit juices from molds and yeasts and it is
very active in the presence of carbon di oxide.
• When potassium meta sulphite is added to fruit juices, it releases sulphur
di oxide which in turn react with water to form sulphorous acid. As this acid
level increases to 350ppm or above, molds, their spores, yeasts and
bacteria are destroyed. Therefore, the fruit juices can be bottled and stored
for several months.

12. Fermentation
• Many fruits and vegetables are preserved by
fermentation process.
• During fermentation, alcohol content increases
in the fruits/ vegetables and protect from
microbial spoilage.
• Fruit juices are fermented to prepare alcoholic
beverages.
• Sauverkrout is a fermented food made from
cabbage.
• Green olives is made by fermentation of Olives.