Cooking foods

A large number of polycyclic aromatic hydrocarbons are known Many have been synthesized m the laboratory and several of the others are products of com bustion Benzo[a]pyrene for example is present m tobacco smoke contaminates food cooked on barbecue grills and collects m the soot of chimneys Benzo[a]pyrene is a carcinogen (a cancer causing substance) It is converted m the liver to an epoxy diol that can induce mutations leading to the uncontrolled growth of certain cells... 

Figure 1.4a. Iron concentration in raw and cooked foods. For braked foods, comparisons are between dough and baked product. For stew ingredients, raw foods are compared to foods cooked together in an iron pot.

In 1932, nine out of ten kilos of textiles the Germans used had been imported. This ratio applied to most other household things. Farben went into the forests. Soon every other citizen arose to the tinkle of a Farben plastic clock, rolled back a new synthetic-fabric spread. Every other man shaved with Farben soap that had been made from the residue of the paraffin that had been made from the coal. At least twice a week, the German ate a new Farben food cooked in synthetic fat. Six out of ten dinner tables were spread with Farben cloths. After the worker went to his job, his wife cleaned the linen, the curtains, the casements, and dusted the furniture goods — all made from beechwood. 

A pressure cooker is a sealed saucepan in which food cooks faster than it does in a simple saucepan - where simple , in this context means a saucepan that is open to the air. A pressure cooker is heated on top of a cooker or hob in the conventional way but, as the water inside it boils, the formation of steam rapidly causes the internal pressure to increase within its sealed cavity see Figure 5.11. The internal pressure inside a good-quality pressure cooker can be as high 6 atm. 

Figure 5.11 A pressure cooker enables food to cook fast because its internal pressure is high, which elevates the temperature at which food cooks...

Why does food cook faster at higher pressures ... 

But salted water boils at a higher temperature than does pure water, so the food cooks more quickly. (We saw on p. 203 how a hotter temperature promotes faster cooking.) The salt causes an elevation of boiling point, which is another colligative property. We call the determination of such an elevation ebullioscopy. 

At home, you take advantage of the temperature dependence of chemical reactions all the time. For example, to keep your food fresh, you store it in a refrigerator. If you have ever left milk or vegetables in the refrigerator for several weeks, however, you have probably observed that refrigeration does not stop food from spoiling. Instead, it decreases the rate of the reactions that cause spoilage. When you want to cook your food quickly, you increase the temperature of the stove. This increases the rate of the reactions that take place as the food cooks. 

An intake of 25—75 mg Fe d may be safe. Long term iron overload has been noted in South Africa (Bantu siderosis). Ingestion of up to 200 mg Fe d-1 may be the result of eating food cooked in iron pots or drinking Kaffir beer containing 15-120 mg Fe 1 1. Ethiopians have a high iron intake (up to 500 mg d-1), but as siderosis is not common, much of this iron must be unavailable.33 This type of hemosiderosis should be treated by preventative measures to restrict the amount of iron in the diet.48... 

Explain why food cooks faster in a pressure cooker. 

Greger JL, Goetz W, Sullivan D. 1985b. Aluminum levels in foods cooked and stored in aluminum pans, trays and foil. J Food Prot 48 772-777. 

Because of inhalation of smoke, especially tobacco smoke, the lungs are the most likely sites of cancer from exposure to PAH compounds. However, these compounds are also found in foods cooked under direct exposure to pyrolysis conditions and are suspected of causing cancer in the alimentary canal. Extraordinarily high rates of esophageal cancer have been observed in Linxian, China, and may be attributable to PAHs from unvented cookstoves.13 In this study, the glucuronide conjugate of 1-hydroxypyrene was monitored as a biomarker of exposure to PAH compounds (Figure 13.11). 

A major incident of TOCP poisoning affected 10,000 people in Morocco in 1959. The victims had eaten food cooked in olive oil adulterated with TOCP-contaminated lubricating oil. A number of cases of permanent paralysis resulted from ingestion of the contaminated cooking oil. 

In the extrusion of snack foods, cereals and pet foods, cooking prior to extrusion is required. This can be accomplished in a steam pressure cooker integral with the extruder such as shown in Fig. 5.17. Screw diameters up to 10 in. (25 cm) are used in this application yielding typical capacities of 4,000 lb/h (1.8 Mg/h) with a 50 hp (37 kW) extruder drive to 12,000 lb/h (5.4 Mg/h) with a 150 hp (112 kW) extruder drive, depending on formulation and product requirements. 

You could be exposed to acrolein in many other ways that have nothing to do with hazardous waste sites. Acrolein can be formed by the breakdown of many pollutants found in outdoor air. Burning tobacco and other plants forms acrolein, and you breathe acrolein when you smoke tobacco or are near someone who is smoking. You also breathe acrolein when you are near automobiles, because burning gasoline forms acrolein, which enters the air. If you live near an oil or coal power plant, you breathe small amounts of acrolein. Acrolein is formed when fats are heated. Small amounts of acrolein may also be found in foods such as fried foods, cooking oils, and roasted coffee. You could breathe acrolein if you work in an industry that uses acrolein to make other chemicals. 

Functional Use in Foods Cooking or salad oil component of margarine or shortening coating agent emulsifying agent formulation aid texturizer. 

The potential toxicity of PCBs to humans first came into the public arena in 1968, when over 1,500 people around Fukuoka in south-west Japan were poisoned by eating food cooked in rice oil contaminated with PCBs. This was not a single (acute) poisoning incident as the victims used the contaminated rice oil for cooking for some three months. The oil had become contaminated with PCBs as a result of a leak in the machinery in the plant producing the rice oil. People started to suffer from various diseases, and the illness became known as Yusho disease (meaning rice oil disease). Most prominent was chloracne, a severe effect on the skin which is also caused by dioxins. Babies born to women who were exposed also showed symptoms of the disease. Eventually some 2,000 cases of Yusho disease were recorded. 

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