The toxicology of antioxidants has become one of the more controversial areas in the continuing debate on the safety of food additives. In recent years, problems have arisen with the antioxidants butylated hydroxyanisole (BHA) & butylated hydroxytoluene (BHT) when new long-term studies showed that these compounds could produce tumours in animals. Chemicals which have been shown to cause cancer in long-term animal studies are normally not permitted as food additives, & regulatory authorities would have little hesitation in making such a decision in the case of any new chemical submitted to them for approval which appeared to be a genotoxic carcinogen. However, with BHA & BHT, not only did the new findings conflict with the results of earlier, negative, long-term studies, but also their significance for hazard assessment in man was surrounded by even more uncertainties than those which toxicologists are used to considering when extrapolating from animal experiments to man.

Toxicological Aspects of Antioxidants Used as Food Additives

Antioxidants are components which prevent auto-oxidation of oils and fats by giving their hydrogen to free radicals formed in the initiation and propagation stages of autoxidation. During the past two decades, a lot of researches using natural plants extract in edible oils have been carried out due to the trend to minimize or avoid the use of synthetic food additives. According to the most studies, there are various natural antioxidants which can be extracted from low cost resources, such as most parts of olive plant, green tea, sesame, medicinal plants, etc. One of the most important requirements for a suitable antioxidant in oils and fats is the thermal stability during heat processing. It has been shown that most of natural additives have more antioxidants activity and thermal stability than synthetic ones in different edible oils. In this review, recent advances in the application of natural antioxidants in the food industry will be covered.

Application and stability of natural antioxidants in edible oils in order to substitute synthetic additives

Glutamate. Its applications in food and contribution to health.

Antioxidative activities of Olea europaea leaves and related phenolic compounds

Sulphites in various forms have been added to foods for centuries. Their use became an issue of concern when certain sensitive individuals exhibited adverse reactions to sulphite residues in foods. Analytical methods were developed to monitor these compounds at the regulatory limit of 10 ppm. In this report, analytical methods for determining sulphites in foods are reviewed, along with a critique of their chemistry and procedural schemes. An assessment of the key features of each method category is presented together with some comparative data. The classification scheme used is based upon the fact that determination of the sulphite content of a food is influenced more by the treatment and cleanup of the test solution than by the final determinative step. Based on a 60-year database, the Monier-Williams procedure still remains the method of choice.

A review of sulphites in foods: Analytical methodology and reported findings

Fate of antioxidants and antioxidant-derived products in deep-fat frying and cookie baking.

Reactions of antioxidants in foods

The objective of this work was to develop a reliable, rugged high-performance liquid chromatographic (HPLC) method for determination of trace levels of bromate (< 10 micrograms/l) in bottled water. HPLC separation was achieved by ion interaction chromatography using a C-18 reversed-phase column and a mobile phase consisting of methanol/water (20:80, v/v) with tetrabutylammonium acetate as the ion interaction reagent. A post-column reaction based on oxidation of o-dianisidine in acidic solution to a product detected at 500 nm provided selective measurement of the oxidants. The limit of detection and the limit of quantitation were 1 and 3 micrograms/l, respectively. Iodate, chlorite, and nitrite were chromatographically separated from bromate and measured by monitoring the post-column reaction. Chloride and chlorate at levels that might be found in bottled water did not interfere with the determination of bromate. Bromate was detected in bottled waters at concentrations up to 40 micrograms/l.

Measurement of bromate in bottled water by high‐performance liquid chromatography with post‐column flow reactor detection

A survey of free glutamic acid levels in a variety of foods was conducted. The foods were analysed by high-performance liquid chromatography (HPLC). Free glutamic acid was extracted from the food with 0.02 M potassium phosphate with subsequent precipitation of other food components with acetone. Impurities were removed by passing the extract through a C-8 or C-18 reversed-phase solid-phase extraction column. The free glutamic acid was derivatized with phenylisothiocyanate, and the derivative was separated by HPLC with detection at 254 nm. Free glutamic acid levels ranged from not found (< 20 ppm) in some spices to as high as 89% in another spice.

Determination of free glutamic acid in a variety of foods by high-performance liquid chromatography.

The Monier-Williams distillation procedure has a long history of successful use for determining sulfite in fruit products and wine; however, a systematic evaluation of its accuracy and precision with other food matrices has not been undertaken We found that the Monier-Williams distillation yielded greater than 90% recovery of sulfite added to foods such as table grapes, hominy, dried mangoes, and lemon juice Less than 85% recovery was obtained with broccoli, soda crackers, cheese-peanut butter crackers, mushrooms, and potato chips These results may, in fact, accurately reflect the residual levels of sulfite if a portion of the sulfite undergoes irreversible reaction with some food components Analysis of commercial food products gave sulfite levels ranging from 1400 ppm in dried apple slices to 25 ppm in cream sherry

Daniel H. Daniels

Papers

Fate of antioxidants and antioxidant-derived products in deep-fat frying and cookie baking.

Reactions of antioxidants in foods

Measurement of bromate in bottled water by high‐performance liquid chromatography with post‐column flow reactor detection

Determination of free glutamic acid in a variety of foods by high-performance liquid chromatography.

Reevaluation of Monier-Williams method for determining sulfite in food.