Halogen Oven and Food Safety

1. Halogen oven (turbo cooker) is regarded by some people as an energy efficient and healthy alternative to conventional oven. Similar to conventional oven, halogen oven can also produce brown and crispy food. Previously, media reports stated that consuming foods cooked with halogen oven may increase the intake of carcinogens which can be formed in a way similar to cooking by grilling. This has raised public concerns on the food safety of using halogen oven.

Introduction to Halogen Oven

1. In general, a halogen oven consists of a glass bowl with a lid that contains a fan and halogen bulbs. When switched on, beams of infrared (or more specifically, far-infrared) radiation are released from the halogen bulbs to produce heat. The fan circulates hot air over and around the food to cook. Halogen oven can be used to roast, grill, bake, steam, barbecue or dehydrate food, with no need of preheating.

2. When food is exposed to the infrared radiation, large amounts of energy are transferred in a short time. The energy induces water molecules and organic compounds, such as proteins, fats and starches, to vibrate/rotate, producing heat to kill microorganisms and give the food brown and crispy surface. In the food industry, infrared is used as a means of thermal disinfection to inactivate bacteria, spores, yeast and mould in both liquid and solid food. Disinfection via infrared can allow freshly baked bread to enjoy a longer shelf-life without the addition of preservatives. It can also be applied to dehydrate vegetables for preservation.

Food Safety Regarding the Use of Halogen Oven

1. The cooking process of the halogen oven is also a type of dry - heat cooking which either air or fat is used as the medium of cooking . A higher temperature can be achieved as compared with moist-heat cooking, which uses water and steam as the medium of cooking.

2. During the dry-heat cooking process, the high temperature (usually well above 100 °C) can cause chemical changes in the major components in food (i.e. carbohydrates, fats and proteins) and subsequently generate process contaminants, such as acrylamide, polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HCAs). Acrylamide as well as certain PAHs, and HCAs have been shown to cause cancer in experimental animals while benzo[a]pyrene, a PAH, is carcinogenic to humans.

3. The formation of HCAs and PAHs depends on the meat type, the cooking method, and "doneness" level. Muscle (the protein-rich part of meats) cooked at high temperatures, or that are cooked for a long time tend to form HCAs. Cooking methods that expose meat , especially high-fat meats, to smoke or charring contribute to PAH s formation. These contaminants can be found in charred foods, barbecued meats, and "Siu Mei", etc.

4. On the other hand, acrylamide is an inadvertent contaminant produced by cooking food, generally above 120°C. Information shows that acrylamide is formed when certain foods, particularly plant-based foods that are rich in carbohydrates and low in proteins, are cooked at high temperatures such as in frying, roasting or baking. Major food items with higher levels of acrylamide include potato chips, crisps, coffee, pastries, cookies, bread, rolls and toasts. In addition, certain stir-fried vegetables, including Chinese flowering cabbage, water spinach, zucchini and onion were detected with relatively high level of acrylamide in a study conducted by the Centre for Food Safety.

5. According to available product information of certain type of halogen oven, temperature setting of the oven can be ranged from 50°C to 250°C and the high temperature is comparable to certain types of dry-heat cooking shown in the table below . As such, it is believed that the said process contaminants resulting from high temperature cooking may also be present in food prepared by halogen oven, depending on the time and temperature for cooking etc.

Temperature of dry-heat cooking methods:

Methods Cooking Temperatures
Deep-frying ~160 ° C – 180 °C
Baking Up to ~220 °C
Charcoal grilling Up to ~370 °C
Gas/electric grilling Up to ~315 °C

6. However, halogen oven carries an emitter that releases infrared radiation, where large amounts of energy are transferred in a short time. This may help to reduce the cooking time which in turn may reduce the levels of certain process contaminants in food.

7. With regards to the risk of PAHs, halogen oven is a safer choice than charcoal grilling for making barbecued meat, as it does not expose meat to smoke and avoids direct contact of meat with flame.

Advice to Users

Risk Assessment Section
October 2013