Phenolic Compounds

Plant phenolic and polyphenolic compounds, are defined as compounds possessing one or more aromatic rings bearing hydroxyl substituent(s), and are the secondary metabolites of phenylalanine and to a lesser extent tyrosine in plants.

 Phenolic compounds mostly present in various types of foods of plant origin. Natural antioxidants have been extensively found in fruits and vegetables, seeds of many fruits, cereals, berries, wine, tea, olive oil, and aromatic plants. The content of phenolic compounds in foods may change during processing and storage as mediated by light and temperature.

There is now considerable evidence that wine phenolics, particularly resveratrol, inhibit low-density lipoprotein oxidation and reduce platelet aggregation, two major parameters implicated in atherothrombogenesis. This provides a possible explanation for the cardio protective action of wine.

Phenolic compounds such as cafeic acid, chlorogenic, p-coumaric and ferulic are present in parts of plants that are used as spices. The antimicrobial activity of these and other acids as hydroxycinnamic and cinnamic may retard microbial invasion as well as fruit and vegetable putrefaction.

Apart from being naturally present in the raw materials used for foods, phenolic compounds are also added to certain foods and beverages as colorants or as antioxidants. Phenolic compounds have also been successfully employed as the processing aid for texture modification of fish mince and surimi.

The potential value of phenolic compounds as biopreservatives is considered for the safe extension of perishable products shelf life and these substances can be used to delay or inhibit the oxidation and growth of microorganisms. However, in food applications, the phenolic compounds could be influenced by food components, processing and storage.
Phenolic Compounds

Phenolic compounds as food additive

Plant phenolic and polyphenolic compounds, can be defined as compounds possessing one or more aromatic rings bearing hydroxyl substituent(s), and are the secondary metabolites of phenylalanine and to a lesser extent tyrosine in plants.

Polyphenols are the natural antioxidants prevalent in fruits, vegetables, beverages (tea, wine, juices), plants, seaweeds, and some herbs and show antioxidative and antimicrobial activities in different fish and fish products.

These compounds are too directly related to sensory characteristics of foods such as flavour, astringency, and colour.

The use of phenolic compounds also appears to be a good alternative for sulphiting agent for retarding melanosis in crustaceans. Phenolic compounds have also been successfully employed as the processing aid for texture modification of fish mince and surimi.

Phenolic antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and monotertiary butylhydroquinone (TBHQ) are hindered phenols with antimicrobial activity. The use of phenolic antioxidants in food products is regulated by federal agencies. In general, these compounds are permitted in concentrations up to 200 ppm, based on the fat or oil content of the food product.
Phenolic compounds as food additive

The Effectiveness of Antioxidants

The Effectiveness of Antioxidants
Some antioxidants lose their effectiveness when they combine with oxygen; therefore, there is no advantages to using this type of antioxidant unless the food is enclosed in a system from oxygen or air can be excluded. In the use of antioxidants, it should be kept in mind that other precautions are necessary to minimize oxidation since heat, light, and metals are prooxidants, that is, their presence favors oxidative reactions.

Many of the antioxidants used in commerce occur naturally in foods (e.g., vitamin C, citric acid, amines, and certain phenolics compounds). However, the amines and the phenolics compounds can be toxic to human in low concentrations; therefore, they and the synthetic antioxidants require strict regulations of their use in foods.

It should be pointed that the potency of the naturally occurring antioxidants is not as great as that of the commonly used synthetic antioxidants. The antioxidants that are considered to be the most effective and therefore are most widely used are butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and propylgallate.

These are usually used in formulations that contain combinations of two or all three of them, and often in combination with even fourth component, very often citric acid. The main purpose in adding citric acid is for its action as a chelator.

Fats and shortening, especially those used in bakery goods and fried foods, are subject to oxidation and the development of rancidity after cooking. To prevent this, chemical antioxidants in concentrations up to 0.02% of the fat components may be added.
The Effectiveness of Antioxidants