The science of cooking
In praise of oysters
The humble oyster inspires passion in many and fear in others. Sam Wong looks at a scientifically sound (hợp lý, dựa trên cơ sở khoa học) way to eat them
I LOVE raw oysters, so hoped to write a column saying there is no need to worry about food poisoning (ngộ độc thực phẩm). When I looked into (nghiên cứu kỹ) it, though, I found cause for concern. But there are safe ways to enjoy delicious oysters.
Folklore has it that oysters can be eaten in any month with an “r” in it — in other words, avoiding the summer months, when they spawn (sinh sản). This discernment (sự nhận thức, hiểu biết) may date back (có từ thời) to ancient times.
By measuring parasitic snails in oyster shells, a study of a 4300-year-old human habitation in Georgia, US, found that ancient people mostly harvested (chủ yếu thu hoạch) oysters in the autumn, winter and spring.
During their spawning season, oysters convert (chuyển đổi) their resources into sperm or eggs, which renders them less palatable (dễ ăn, ngon miệng). People may also have avoided (tránh) taking oysters in summer to allow (cho phép) populations to recover.
Nowadays, farmed oysters are available and good to eat all year round (quanh năm) and are among the most sustainable seafoods (hải sản bền vững). Since the 1980s, many farmed oysters have been triploid: they have three sets of chromosomes and are therefore infertile (không sinh sản được). These oysters grow faster than natural oysters and remain firm and plump (mập mạp, đầy đặn) in the summer.
As filter-feeders (sinh vật lọc thức ăn từ nước), oysters can pick up pathogens lurking (mầm bệnh ẩn náu) in the water. To reduce this risk (giảm thiểu rủi ro này), they are usually kept in clean water for 42 hours after harvesting in the UK, a process called depuration.
Sadly, this isn’t completely effective — particularly with respect to norovirus, one of the most common causes of gastroenteritis (viêm dạ dày ruột). A 2017 report found that between 100 and 1000 copies of the norovirus genome may remain in each gram of oyster tissue after depuration. Just 10 copies are enough to constitute (cấu thành, tạo thành) an infectious dose.
In the UK, about 13,000 people a year experience illness after eating seafood, usually raw oysters. Given that more than 13 million oysters are served each year, you might consider this a low risk. But recent headlines about raw sewage discharged (nước thải chưa xử lý được xả ra) around British coasts may make you think twice (suy nghĩ lại).
Fortunately, cooked oysters are delicious too. The simplest method is to oven cook oysters at 220°C for 10 minutes. Heat will cause the shell to open, so place them on a wire rack (vỉ sắt) or a bed of salt to stabilise them, so the juice doesn’t leak out (rò rỉ ra ngoài). Once cool enough to handle (xử lý, cầm được), use a knife to gently separate the oyster from the shell. To serve, spoon on some melted butter and garlic, hot sauce and lemon juice.
Champagne is another traditional accompaniment to oysters, and a study identified a reason behind this pairing (sự kết hợp). Oysters and champagne contain compounds that activate umami (vị ngon ngọt đậm đà) taste receptors (thụ thể vị giác): glutamate from dead yeast cells (tế bào men chết) in champagne and nucleotides in the oyster muscles. Combined, they create a stronger perception (cảm nhận) of umami than either does on its own (một mình).
(These articles are posted each week at newscientist.com/maker 20 November 2021 | New Scientist | 51)
Questions 1–6
Do the following statements agree with the information given in the passage?
Write:
-
TRUE if the statement agrees with the information
-
FALSE if the statement contradicts the information
-
NOT GIVEN if there is no information on this
1. Oysters used to be consumed exclusively during cooler months due to ancient health practices.
2. Scientific analysis of prehistoric oyster shells revealed that people consumed oysters regardless of the season.
3. Modern farming has created oysters that are incapable of reproducing, ensuring year-round quality.
4. Rinsing oysters in clean water for 42 hours completely eliminates all harmful viruses.
5. Research shows that raw oysters in the UK are the direct cause of over 13,000 food poisoning cases each year.
6. Champagne enhances the salty flavor of oysters by neutralizing sour compounds in their flesh.
SUGGESTED ANSWERS
1. Oysters used to be consumed exclusively during cooler months due to ancient health practices.
TRUE
Extract:
“…a study of a 4300-year-old human habitation in Georgia, US, found that ancient people mostly harvested oysters in the autumn, winter and spring.”
2. Scientific analysis of prehistoric oyster shells revealed that people consumed oysters regardless of the season.
FALSE
Extract:
“…found that ancient people mostly harvested oysters in the autumn, winter and spring.”
3. Modern farming has created oysters that are incapable of reproducing, ensuring year-round quality.
TRUE
Extract:
“…many farmed oysters have been triploid… and are therefore infertile. These oysters grow faster than natural oysters and remain firm and plump in the summer.”
4. Rinsing oysters in clean water for 42 hours completely eliminates all harmful viruses.
FALSE
Extract:
“Sadly, this isn’t completely effective — particularly with respect to norovirus…”
5. Research shows that raw oysters in the UK are the direct cause of over 13,000 food poisoning cases each year.
TRUE
Extract:
“In the UK, about 13,000 people a year experience illness after eating seafood, usually raw oysters.”
6. Champagne enhances the salty flavor of oysters by neutralizing sour compounds in their flesh.
NOT GIVEN
Extract:
“Oysters and champagne contain compounds that activate umami taste receptors… Combined, they create a stronger perception of umami…”