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Monday, 10 January 2011

Understanding Fruits & Vegetables - Part 2

 Handling and Storing Fruits & Vegetables


In Part 1 of Understanding Fruits & Vegetables, I have extensively covered how to choose the right produce and what to avoid; all in the attempt to have the best quality fruits and vegetables in our diet as well as in our cooking. After all good cookery starts with good quality produce. 

Having picked the right produce, Handling and Storing know how’s help you keep it in the best conditions to ensure relative longevity and freshness. This part is dedicated to understanding best practices in Handling and Storing your Fruits and Vegetables.

Good To Know: 
Why do fruits and vegetables get spoilt?
The spoilage of fruits and vegetables is caused by microbes which are always on their surface as well as in the air. Bacteria, Moulds, and yeasts attack the weak and damaged plant tissue, breaking down the cell walls, consuming its content and leaving behind their unpleasant waste products. Vegetables are attacked by Bacteria, which grow very fast, making them decay faster than fruits, which are more acidic and therefore more resistant to Bacteria. However, Fruits are readily attacked by Yeasts and moulds.

Pre-cut fruits and vegetables are convenient (the ones cut at home, or store-bought), they do make your time in the kitchen shorter, but are more susceptible to deterioration and spoilage. Therefore do not opt to buying those, unless you know they will be consumed shortly.

Soil harbors Bacteria and must be removed before storage

Handling Fresh Fruits and Vegetables
The aim of fresh produce storage is to slow the inevitable deterioration. Here are the main  guidelines to proper Handling of produce before and during storage:

  • Choose the right fruits (read part 1)
  • Fruit bowls and refrigerator drawers should be cleaned regularly to reduce the microbial population.
  • Bear in mind that Mushrooms as well as some ripe fruits (berries, apricots, figs, avocados, papayas...etc) have a naturally high metabolism and therefore deteriorate faster than apples, pears, kiwis, cabbages, carrots and other good keepers.
  • Mouldy fruits and vegetables should be discarded straight away. “1 rotten apple spoils the barrel.”
  • Your produce shouldn't be subjected to physical stress, whether dropping apples on the flour or packing tomatoes tightly into a confined space, as this leads to bruising and possible breakage, which eventually exposes the protected interior to microbes leading to its depletion and spoilage.
  • Even rinsing in water can lead to spoilage, in the case of berries for instance, as rinsing can make them more susceptible to infection by abrading their protective layer. Therefore they should only be rinsed, right before use, not before storage.
  • Soil harbours large numbers of microbes and should be removed from the surface of sturdier produce, potatoes for example, before storing them.


Leaves, greens should be stored
 in closed containers
Proper Storage Requirements:
The longevity of stored produce is strongly affected by the atmosphere it is stored in. Plant tissue is mostly water, and therefore require a humid atmosphere to avoid drying out, damaging its internal system. In practice, this means, keeping plant foods (leaves, herbs, greens...etc) in restricted spaces (plastic bags, drawers within a refrigerator). This slows down moisture loss. However, plants breath out carbon dioxide and water, which will accumulate too much moisture on its surface. Too much humidity encourages microbial attack. Therefore, lining the container with absorbent material will delay condensation (tissue paper, a towel, or even a paper bag are all absorbent materials that can be used for storage). 


Deterioration can also be slowed down by limiting stored plant’s access to oxygen. This can be done by squeezing the air out of the bags when sealing them. With that said it is also important to know that bagging promotes ripening, which means storing produce in closed bags will have them pass from ripe to over-ripe too quickly, and therefore must be consumed fast. Don’t forget, one damaged leaf can speed the decline of a whole lettuce head. You therefore need to check on your produce regularly, and consume it relatively fast. After all, these steps will help you keep them for relatively longer periods, but not forever!

A very common commercial treatment that slows down water loss and oxygen uptake in whole fruits and vegetables is waxing (read about waxing in part 1). Also commercial packers are now using container inserts that contain permanganate to destroy ethylene and elongate storage. There are many procedures and products that can be used on a commercial level and in large professional kitchens to maximise storage conditions, but the points above are the most common for home storage.

Temperature control is also a very common storage condition. Temperature controlled areas like a cold room, a fridge, or a freezer are all common for food storage.

In the Fridge: 
Cooling slows down chemical reactions in general, also slowing down the growth of microbes. A reduction of just 5°C can double storage life. However, different fruits and vegetables are stored at different temperatures. In general, the produce native to cool climates are best kept at near freezing point. Meanwhile, those native to warmer climates will be injured by those low temperatures. Like for instance bananas, their skin will turn black in the fridge, and avocados darken and fail to soften further in the fridge. 


Foods of tropical and subtropical origins, keep best at relatively higher temperature, room temperature rather than in the fridge. Bear in mind that room-temperature here is referring to temperatures 10-18 °C not 40°C! Therefore storage facilities in the gulf region for instance, or other regions during warmer seasons, need to be temperature controlled too.



In the Freezer: 
Freezing is the most drastic form of temperature control. It stops the overall metabolism of fruits, vegetables and spoilage microbes. How it works: Freezing causes all the water to crystallise therefore immobilising other molecules and suspending chemical activities. Microbes are hardy and most of them revive after warming. But it is worth knowing that freezing kills plant cells causing it to become limp and wet, lacking crispness. Frozen food producers limit the damage by freezing food as quickly as possible (the new methods of shock freezing, do just that, were foods are frozen up to -40°C in no time). Under these conditions only small crystals form which do less damage than larger crystals to the plant cells. Home and restaurant freezers are warmer than commercial freezers and their temperature fluctuate so some water melts during freezing causing the food’s texture to suffer.

Although freezing reduces activities it can also include enzymatic break-down of vitamins and pigments. Blanching is the best solution to this problem and is widely used in restaurants and at home before freezing. Blanching is when food is immersed in rapidly boiling water for a minute or two (to inactivate the enzymes), and then just as rapidly immersed in cold water to stop the cooking process which softens the plants. If vegetables are to be frozen for more than 2 days, they are to be blanched first. Fruits are rarely blanched as their cooked flavours and textures are less appealing. Therefore the enzymatic browning of fruits is stopped by packing it in sugar syrup (680g sugar per 1 litre water) supplemented with ascorbic acid (1/4 – ¾ tsp per quart). This process also improves the texture of fruits as the sugar is absorbed into the walls of the fruits making them firmer. 


Frozen produce should be packed as air-tight and water free as possible. Surfaces exposed to the relatively dry atmosphere of the freezer develop freezer burn. Freezer burnt patches, develop a tough texture and stale flavour. This is especially relative for restaurants and kitchens that use freezer rooms. You cannot place foods exposed in a freezer room.

Canning is another storage method, in which foods are first prepared and then placed in a jar or in the commercial sense a can, which is then firmly closed. Containers are usually sterilised before canning to ensure no bacteria populates them. I have covered canning in my Figs Jam post.


Below are the guidelines on storing the most commonly consumed Fruits and Vegetables:


Asparagus
Asparagus Wrap the bases of fresh Asparagus in wet paper towels and keep upright in a tightly sealed storage container for up to 4 days.

Green Beans Refrigerate in covered container for up to 5 days.

Beets
Beetroots (Beets) Trim the beet greens, leaving an inch or 2 of the stem. Do not cut the long root. Store unwashed beets in an open container in the fridge for up to 1 week.

Broccoli  Keep unwashed broccoli in a covered container for up to 4 days.
 
Brussels Sprouts Refrigerate in a covered container for up to 2 days. Or in their net bag for up to 4 days, making sure to remove any wilted leaves.

Cabbages Refrigerate in covered container up to 5 days, making sure to remove wilted leaves.

Carrots Refrigerate in plastic bags up to 2 weeks.

Cauliflower  Refrigerate in covered container up to 5 days.
Celery


Celery   Refrigerate tightly wrapped up to 2 weeks.

Cucumbers  Keep salad cucumbers in fridge for 10 days. Pickling cucumbers should be picked and pickled the same day.


Eggplants Refrigerate whole eggplants for up to 2 days.


Fennel Refrigerate tightly wrapped up to 5 days.



Leeks Refrigerate tightly wrapped up to 5 days.

Mushrooms A paper bag or damp cloth bag makes them breath and so stay firmer for longer. Store them unwashed.

Onions  Store in a cool, dry, well ventilated place for several weeks.

Peas and Pea Pods (snow peas, sugar snap peas, or fresh peas) Store tightly wrapped in fridge for 3 days.
Turnips

Peppers (Sweet and Hot)  Refrigerate in covered container (drawer) to 5 days.

Potatoes Store in dark, well ventilated place that is cool and slightly humid (not wet), for several weeks.
-       Bright lights cause potatoes to develop green batches that are bitter. The fridge causes potatoes to darken when cooked and become sweeter.

Parsnips  Refrigerate for up to 2 weeks.

 Turnips Refrigerate for up to 2 weeks.

Shallots Store in a cool, dry, well ventilated place for up to 1 month.

Summer squash
 Winter Squash  Store whole squash in a dry, cool place for up to 2 month.
Store cut squash wrapped in plastic in the fridge for up to 2 days.

Summer Squash  Refrigerate tightly wrapped in the fridge for up to 5 days. Fresh from the garden squash can be stored for up to 2 weeks.

Sweet Potatoes Store in a cool, dark, dry place for up to 1 week.

Tomatoes When stored in the fridge, tomatoes lose their flavour. Ideally they should be stored at room temperature for up to 3 days. In warmer areas either buy tomatoes daily or store at room temp for 1 day.
 
Zucchini Refrigerate tightly wrapped in the fridge for up to 5 days. Fresh from the garden squash can be stored for up to 2 weeks.





Cantaloupe

Storing Fruits


Apples Refrigerate for up to 6 weeks. Store bulk apples in a cool moist place.

Apricots Refrigerate ripe fruits up to 2 days.



Avocados    Store at room temperature to ripen. Refrigerate ripened fruits for up to 4 days.
Note that refrigeration darkens the colour of the avocados.

Bananas   Store at room temperature to ripen to bright yellow. Overripe bananas are brown.

Blackberries, Raspberries, Strawberries, Blueberries and Boysenberries  Refrigerate berries in a single layer, loosely wrapped for up to 2 days. Rinse right before use, not before storage.
 
Cantaloupe Refrigerate ripe whole melon up to 4 days. Refrigerate cut fruit up to 2 days in a tightly wrapped or covered container.
 
Star Fruit    Refrigerate ripened fruit up to 2 weeks in a tightly wrapped or covered container.

Cherries Refrigerate in a covered container for 2-3 days.

Cranberries Refrigerate up to 4 weeks or freeze up to 1 year.

Grapefruit Refrigerate up to 1 week.

Grapes Refrigerate in covered container up to 1 week.

Honeydew melon Refrigerate ripe whole melon up to 4 days. Refrigerate cut fruit up to 3 days in a tightly wrapped or covered container.

Lemons   Refrigerate up to 2 weeks.

Limes   Refrigerate up to 2 weeks.

Oranges   Refrigerate up to 2 weeks.



Peaches and nectarines Refrigerate up to 5 days.

Pears  Refrigerate up to 5 days.

Pineapples   Refrigerate up to 2 days. Cut fruits last a few more days if placed in a tightly covered container and refrigerated.

Figs  Place fresh figs in a single layer in a paper towel lined container. refrigerate for up to 3 days. Store dried figs in a an airtight container and refrigerate up to  6 months or freeze up to 1 year.

 
Fig Types





















Plantains This starchy fruit must be cooked before eating. They change from green to yellow-brown then to black. Black plantains are fully ripe. 

Plums  Refrigerate up to 3 days

Rhubarb Wrap stalks tightly in plastic wrap and refrigerate for up to 5 days.


Watermelon Refrigerate whole watermelon up to 4 days, and cut fruit up to 3 days in a closed or tightly wrapped container. Watermelon does not ripen after picking.

Guava Refrigerate ripened fruit up to 5 days.

Kiwi (green) Store ripened fruit in the fridge for 2- 3 weeks.

Papaya Refrigerate ripened fruit in covered container up to 3 days.
 
Pomegranate
 Pomegranate Store seeds in freezer bag up to 1 yera in freezer. Store several weeks in fridge.

Mango Refrigerate ripened mango up to 5 days



Passion Fruit 
Refrigerate ripened fruit up to 1 week.



You now should be able to store your produce right, ensuring freshness for best results in flavour and texture. This information is also particularly useful in the planning process - before you do your shopping. Plan your week’s intake of produce to minimise waste. Also don’t buy your perishable fruits many days before consumption. Knowing how to store fruits can help you determine how to plan your meals ahead, especially if you are entertaining and need to manage your space and time. 

Knowing your food, as well as how to manage and store it is the base of your kitchen experience. No matter how good a cook you are, you cannot fix a rotten apple! And you cannot create the perfect pie out of those rotten apples. 
It all starts with the produce!


Thank you for reading this post, the list is long, but the post had to be comprehensive. I am hoping that these 2 parts of Understanding Fruits & Vegetables will help you maximise on your produce and get the best out of it.  I love nothing more than to hear from you, so don't shy away, leave me a comment before you go:)

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