Nature's Chemistry: Oxidation of Food

Nature’s Chemistry: Oxidation of Food

Basics of Oxidation

• Oxidation refers to a chemical reaction where a substance loses electrons, often involves the gain of oxygen or the loss of hydrogen.
• In the context of food, oxidation can occur when food is exposed to oxygen in the air, resulting in spoilage or changes in colour, taste, and nutrient value.
• Antioxidants are compounds that slow or prevent the oxidation process, and they play a crucial role in preserving food and maintaining its nutritional value.

Oxidation and Food Spoilage

• When food undergoes oxidation, it may spoil due to the growth of bacteria, mould, or yeast.
• This process can affect the appearance, smell, and taste of food, rendering it unappetising or unsafe for consumption.
• Foods rich in fats and oils are particularly susceptible to oxidation, a process known as rancidity. This results in a foul smell and taste rendering the food unfit for consumption.

Preventing Oxidation in Food

• There are several ways to slow or prevent oxidation in food, often by limiting exposure to air.
• Physical methods include refrigeration or freezing, vacuum packaging, and using modified atmosphere packaging.
• Chemical methods involve the use of antioxidants, which can inhibit the oxidation process and prolong the life of the food product.
• Common antioxidants used in food include ascorbic acid (vitamin C), tocopherols (vitamin E), and butylated hydroxyanisole (BHA).

Implication of Oxidation on Nutritional Value

• Oxidation not only alters the taste and texture of food but can also degrade its nutritional value.
• Essential nutrients such as vitamins C and E, omega 3 and 6 fatty acids, and certain minerals are susceptible to oxidation, leading to reduced health benefits.
• Protecting food from oxidation can help maintain its nutritional value, ensuring that the body receives the necessary nutrients from the consumed food.

Oxidative Browning in Food

• Oxidative browning is a specific type of food oxidation that results in a brown colour in certain foods, such as apples, potatoes and bananas when they’re cut or peeled.
• This process involves an enzyme called polyphenol oxidase (PPO), which catalyses the reaction of phenolic compounds with oxygen to produce a brown pigment called melanin.
• While the browning may affect the visual appeal of the food, it does not usually represent a health risk.

Understanding these processes can help to make informed decisions about food preservation techniques, and consider the impact of these practices on the nutritional value and safety of our food. It also highlights one small way in which chemistry plays a vital role in everyday life.