OYSTERS

“Only another oyster would find an oyster beautiful,” wrote Dr. R. Hedeen in his definitive book on oysters, but to the true aficionado oysters are a thing of beauty. Savour the sheer delight of a succulent oyster, feeling it slip, like silk, down your throat.”.

History I

Oysters best known for their reputed aphrodisiac powers, have been a favourite of food lovers throughout the centuries, beginning with the Roman emperors who paid for them with their weight in gold. Oysters have always been linked with love. When Aphrodite, the Greek goddess of love, sprang forth from the sea on an oyster shell and promptly gave birth to Eros, the word "aphrodisiac" was born.


According to history and legend, pearls are believed to have been formed by a drop of dew, or dragon’s tears falling into the mouth of the pearl. If the drop or tear fell into the pearl from stormy skies, the Oyster would produce a dark coloured pearl and if during good weather a light pearl would be formed. Pearls are the birthstone of July, and were once a royal gem whose use was restricted by Royal Decree. Unfortunately the reality is much less romantic.

The Oyster actually produces a pearl only when foreign material becomes trapped inside the shell. The oyster responds to the irritation by producing nacre, a combination of calcium and protein. The nacre coats the foreign material and over time produces a pearl. Ancient folklore says that oysters should be only eaten in months with “R's” in them. This is due to the fact that way back when there was no suitable refrigeration for the oysters, and those warm months could make them spoil. Naturally the world has now changed and we now have our methods of keeping Oysters fresh so that we can indulge in them no matter the spelling of the month!

Oysters have been an important food since the Neolithic period and were cultivated long before the Christian era. The Greeks served them with wine and the Romans were so enthusiastic about these marvelous mollusks that they sent thousands of slaves to the shores of the English Channel to gather them.

Oyster’s au natural are best served simply with crushed ice and seaweed. Fresh lemon juice or Worcestershire sauces are both good accompaniments. There are also two other classic sauces to be served with raw oysters. The first is a mignonette sauce with shallots and vinegar and the second is Tabasco sauce. Oysters may also be cooked in many ways, such as poaching, marinating, frying, grilling or baking.

Casanova is reputed to have shared fifty oysters a day with his amour du jour, and perhaps once you have relished your first oyster, served simply chilled with a squeeze of lemon and some black pepper, you too will fall in love with this succulent delicacy.

Oyster History II
Ancient Greeks used to serve oysters as an incentive to drink. Romans imported them from England, placed them in salt water pools, and fattened them up by feeding them wine and pastries. Many cultures consider oysters an aphrodisiac.

Great piles of oyster shells in many different areas of the shoreline are evidence of the early voracious appetite for these mollusks.

Early Colonial settlers would eat oysters by the gross (144), rather than by the dozen, with per capita consumption at 10 bushels per year.

Abraham Lincoln used to throw parties at his home in Illinois where nothing but oysters was served.

The "Oyster Line" brought oysters westward via stagecoach to settlers with unwavering penchants who ventured into the wild frontier in search of new land. Hangtown Fry, a then-expensive dish of oysters and eggs, was created in 1849 at Cary House during the Gold Rush Days.

Nowadays, in Europe, a dozen (12) is considered a standard serving size for a course, whereas in the US, a half-dozen (6) is the norm. Americans alone consume over 100 million pounds of oysters per year.
 

FACTS
Millions of people around the world love oysters and know them by their taste and appearance at the dinner table, or by the beautiful pearls they sometimes produce for the pleasure of women.

  • Oysters are one of the most nutritionally well balanced of foods, containing protein, carbohydrates and lipids. They are also an excellent source of vitamins A, B1 (thiamin), B2 (riboflavin), B3 (niacin), C (ascorbic acid) and D (calciferol). Four or five medium size oysters supply the recommended daily allowance of iron, copper, iodine, magnesium, calcium, manganese and phosphorus.
  • Oysters may live up to 20 years. They grow from 1 to 2 inches every year, depending on water temperature and food supply.
  • Oysters often change their sex during their lives, usually starting as males and ending as females. A female oyster can produce over a 100 million eggs during one breeding season but only a few of them will live to see adulthood.
  • Oysters are classified in the phylum Mollusca, class Pelecypoda or Bivalvia, order Filibranchia, family Ostreidae. There are over 400 species of oysters known to men. But the most common and consumed ones are the Crassostrea gigas in Europe, the Crassostrea Virginica in North America, the Crassostrea margaritacea in Southern Africa and the Ostrea sinuata or luteria in New Zealand.
     

The taste of an oyster does not depend on the specie it belongs to. It is rather a reflection of the waters it comes from. How an oyster tastes can be described in many ways: briny, sweet, salty, buttery, nutty…


There is proof that oysters have been around for about 15 million years. Records dating back to ancient Roman times prove that Romans already ate oysters.
The myth about oysters saying that one should never eat them in months that do not have an "r" in their name is simply not true. Oysters can be eaten any time except during their breeding season which varies from place to place. 

The myth began many years ago when transport wasn’t fast and refrigeration not constant. Summer months (month without "r's") would then be a risky time to eat oysters that hadn't been kept chilled or had been out of water for too long. Oysters are soft-bodied animals that have two hard, protective shells (a bivalve). These two hard, rough-textured shells are attached by a muscular hinge (the adductor muscles) at the narrow end.

The shell is generated by the mantle, a thin layer of tissue separating the shell from the soft body. When an oyster is threatened, it closes its shells, using the very strong adductor muscle. Oysters draw in water through their gills, and extract oxygen and filter out floating algae (which they use for food). They can filter over 200 liters (50 US gallons) of water per day! They breathe like a fish, using their gills and have a heart with three chambers and colorless blood.

When a minuscule piece of foreign material gets trapped inside the oyster's shell, the oyster responds to the irritation by producing nacre, a combination of calcium and protein. After a while the layers of nacre become what is known as a pearl. Although the white pearl is the most common, pearls have also been found in colors from yellow to pink to black.

How to open Oysters

When opening oysters, use a knife especially designed for this purpose. The handle is solid and the blade is thick and made of stainless steel so that it will not give a metallic taste to the oyster.
The following is the recommended procedure for opening oysters. It is best to protect one’s hand with a damp cloth in case the knife slips;
 

  • Hold the oyster firmly in one hand, the rounded side on the bottom, so as to lose as little liquid as possible.
  • Place the blade between the shells at the muscle, next to the hinge.
  • Twist the blade, lift the top shell and cut the muscle.
  • Then slide the blade to the back of the oyster to detach it from the shell.

Oyster Selection and Storage

Oysters in the shell must be sold live, by law, as all bi-valves must be. They should feel heavy and full of water. Live ones will be tightly clamped shut, or will clamp shut when tapped. Dead oysters will have loose shells and must be discarded along with those which have broken shells. The flavor is best when they are consumed within 24 hours of purchase.

Store live oysters in the shell, large shell-side down, in a mesh bag or in an open container covered with a damp cloth in the refrigerator (no lower than 1° Celsius) up to five days. Do not seal live oysters in an airtight container, they will not be able to breathe and will die.

Never freeze unshelled oysters. You can refrigerate freshly-shelled oysters in their own liquor for two days, but use them as quickly as you can.

Most commercially-available oysters these days have fairly clean shells. However, if you need to clean them, scrub the beards and dirt from the shells while holding them under cold running water before opening them.

When shucking (opening them) oysters, take care to retain the wonderful juice known as liquor. The liquor should be clear, not cloudy, and should not have any sour or unfavorable odor.

Shelled oysters must be pasteurized and canned or frozen before sale. Canned oysters suffer a loss in flavor from live, fresh oysters and are usually used only in cooked dishes. Smoked, canned oysters are great for appetizers.

Canned oysters will have an expiration date and should be stored refrigerated in their liquor in a covered container once opened.

Frozen raw shucked oysters will keep for up to three months. They should be thawed in the refrigerator and then used as you would fresh oysters for cooking.

Cooked oysters should not be frozen, lest you end up with rubber door stoppers. Use leftover refrigerated cooked oysters within three days.

Oyster Varieties

Oyster variety makes a difference, but the flavor of oysters can also vary widely depending on their growing environment. Factors such as salinity of the water, diet, mineral content of the water and water temperature all affect the flavor.

Generally, those from the coldest waters are considered to be better than those from warmer waters for eating raw. However, there are southern oyster advocates who would say the opposite. For cooked oysters, the difference between Northern-bred and Southern-bred oysters is barely noticeable.

Oyster shells range from two to six inches long, not nearly as large as the one-footers found by early European explorers.

Beware Paralytic Shellfish Poisoning

Commercial shellfish is normally government-inspected so the risk of paralytic shellfish poisoning (PSP) is extremely minimal. The Federal Shellfish Sanitration Program governs licensed commercial fishermen to certify the oysters are fished from uncontaminated waters and safe for consumption.

Oysters, like clams, are susceptible to biotoxins. These biotoxins are found even in waters that appear to be clean and fresh, so don't trust your eyes.

Be familiar with PSP symptoms, emergency treatment procedures and contacts, and always check for status of the waters with your local marine fishery government agency before harvesting your own.
 

Oysters and Your Health

Health officials recommend cooking oysters thoroughly before consuming. Certain high risk groups with medical conditions such as liver disease, cancer, immune deficiencies, hepatitis, diabetes, and others should completely avoid eating raw oysters. However, completely cooking oysters kills harmful bacteria, thus eliminating the danger for these high risk groups.

Oysters are a good source of calcium, needed not only for strong bones, but also to aid in blood clotting, activate enzymes to help with digestion, and help carry nerve impulses. They are also high in vitamin B12, iron, zinc, and copper.
Oysters belong to the love or loathe category of foods.

This shellfish, long thought to hold aphrodisiac properties, are typically slurped raw straight from the shell but are also barbecued, pan-fried or even steamed. Whichever way you choose to eat them, fresh, live oysters require proper handling to be eaten safely. When purchasing live oysters, examine the shells to determine that they are tightly closed, with no gaps in between the two shells. Oysters that have opened prior to cooking should not be consumed, especially if eating them raw. 
 

Grading for size

Live oysters are usually graded into four sizes for sale, grade 1 being the largest; size is determined by measuring the length of the longest axis of the shell. Grade 1 oysters are typically about 100 g, and grade 5 is 35-40 g.
Length and weight of the whole oyster are not necessarily directly related to quality as determined by the amount and appearance of the meat; variation with season and from ground to ground can sometimes result in a large shell containing a small amount of meat of poor appearance or a small shell comparatively well filled with firm meat. Selling price is usually determined within a species by assessment of size, yield and quality. The native oyster is more highly prized than other species and in consequence generally commands a higher price.

Transport and storage of live oysters

Oysters can survive out of water for weeks if carefully handled and kept moist and cool but, since they rapidly lose liquor from within, particularly if the edge of the shell is damaged, they should reach the inland wholesaler within 3 days of harvesting to be in prime condition. They should be carried and stored with the cupped half of the shell downwards, and kept moist by covering with a damp cloth. They should be packed in a manner that protects them from mechanical damage, and should be kept at all times at a temperature between 1 and 10°Celsius. Commercial packaging ranges from a simple barrel, box or sack to a specially designed container with separate compartments for individual oysters, the degree of sophistication depending on the value of the product, the journey time, and the market for which it is destined.

Small holding tanks using artificial sea water can be used to keep live oysters at a wholesaler's premises for a few days. Live oysters stored in a shop or restaurant should be inspected daily, and any that are dead or moribund should be removed. A healthy live oyster feels heavy, sounds solid when tapped, and either remains tightly closed or closes quickly when it is handled. Supplies should be regulated so that oysters are not kept on the premises for more than 3 days.

Shucking

Shucking, that is removal of the meat from the shell or detachment of the meat so that it can be readily removed by the consumer usually done by hand. A right-handed person holds the oyster in a cloth in the left hand, with the flat side uppermost and the hinge towards him. A short bladed oyster knife is inserted between the two halves of the shell, close to the hinge, and twisted to break the hinge and lever the oyster open. The knife is then used to sever the adductor muscle at its point of attachment to first the flat half of the shell, then the cupped half, and the meat removed. If the meat is to be served on the half shell, the detached meat is turned over, cleared of any shell fragments, and left in the cupped half along with the natural liquor.

Many devices have been tried to reduce the labour of hand shucking. These include a means of holding the shell while it is prised open by hand, the shearing off of the hinge by guillotine, and a wide range of treatments that cause the shell to spring open, including the use of chemicals, heat, cold, vacuum, microwaves and lasers. Microwave treatment is difficult to control; a live oyster exposed to microwaves in an oven will usually open in 30-40 seconds, but it is not always possible to avoid the meat being cooked.

Yield and composition of meals

Oyster shells vary considerably in thickness according to origin; consequently the percentage yield by weight of meats is also very variable. The yield of meats from native oysters typically ranges from 6 to 18 per cent, and from Pacific oysters 5 to 14 per cent.

The composition of the meat of the native oyster is 77-83 per cent water, 1-3 per cent fat and 9-13 per cent protein. The energy value of the meat is 3-4 kJ/g.

Oyster meats generally contain 1-5 per cent of the carbohydrate glycogen, but at times the proportion can be as high as 10 per cent. The amount of glycogen is usually least during the breeding season.

Freezing oysters

In shell
 

Only live oysters should be selected for freezing. Whole oysters can be frozen satisfactorily spread in single layers in an air blast freezer. Freezing causes the shells to open and makes subsequent shucking easier.

Oysters can also be frozen in the half shell; they should be laid in single layers on trays in an air blast freezer, with plastics film stretched over each tray to protect the open surfaces of the oysters.

Oysters should never be put into a cold store to freeze. Cold stores are designed only to hold already frozen products at the required low temperature; they do not have the refrigeration capacity to handle large amounts of unfrozen material.

Frozen whole oysters packed in polyethylene bags can be kept in good condition for 6 months in a cold store at -30