Antioxidants in lipid foods and their impact on food quality

Polyamines as radical scavengers and protectants against ozone damage

Inhibition of the bleaching of the carotenoid crocin a rapid test for quantifying antioxidant activity

Emulsions of menhaden oil and sodium caseinate (NaCas) incorporating carbohydrates of varying dextrose equivalence (DE) were spray-dried to yield encapsulated fish oil powders. The effects of carbohydrate DE (5.5-38), core/wall ratio and NaCas/carbohydrate ratio on microencapsulation efficiency (ME) and oxidative stability of spray-dried emulsions were examined. The effect of alpha-tocopherol or Trolox C addition on the oxidative stability of herring oil emulsions and powders was also determined. ME of fish oil powders was greater than 90% in most cases. Peroxide value (PV) of menhaden oil powders decreased on increasing the DE of carbohydrates. PV of menhaden oil powders increased as core/wall ratio increased from 0.33-1.0. NaCas/DE 28 ratio did not affect PV values of powders. The addition of alpha-tocopherol or Trolox C decreased PV throughout the storage period; this effect was most pronounced for alpha-tocopherol added to the oil at a concentration of 100 ppm. Addition of alpha-tocopherol delays the onset of oxidation in stored fish oil powders.

Microencapsulation and oxidative stability of spray-dried fish oil emulsions

In this paper, I shall discuss the important trends of the past seven years in applications of antioxidants in foods. The nature and course of lipid autoxidation and antioxidant action have been treated in a previous paper of this Symposium (Symposium, 1979), as has the effect of water activity. Other papers will deal with the biological effects of antioxidant use, including antimicrobial action. Natural antioxidants will also be treated elsewhere. Therefore, I shall discuss primarily the use of the commonly added synthetic antioxidants (Fig. 1) and four naturally occurring ones — α-tocopherol and ascorbic (Fig. 2), citric and phosphoric acids, which common usage seems to segregate from the “natural” antioxidants. In addition, I shall handle many secondary antioxygenic compounds and treatments, such as oxygen exclusion or scavenging, browning antioxidants, and products produced by fermentation, smoking, nitrite curing, and hydrolysis of vegetable protein.

Recent Trends in Food Applications of Antioxidants

6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid in thin layer tests in vegetable oils and animal fats has two-four times the antioxidant activity of butylated hydroxytoluene and butylated hydroxyanisole and is more active than propyl gallate, nordihydroquaiaretic acid, ascorbyl palmitate, and α- and γ-tocopherols. It is also more active than tertiary butylhydroquinone in chicken and pork fats and corn, peanut, sunflower, and safflower oils in thin layer tests. Tertiary butylhydroquinone is slightly more active in corn, soybean, cottonseed, and peanut oils in the active oxygen method, probably due to decomposition of the chroman at 98 C. This decomposition is inhibited by ascorbic acid. The chroman is synergized by ascorbyl palmitate-thiodipropionate and ascorbic acids. Active oxygen method values of 190 hr are obtained in combination with the latter. A spectrofluorometric assay for 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid has been developed. The compound is 95–100% stable for 2 months at room temperature and 45 C, and a low level of toxicity is found. The copper and iron breakdown products of the chroman have been determined. A possible relationship between these products, protection of the chroman by ascorbic acid and ethylene diaminetetraacetic acid, and a mechanism of action is presented.

W. R. Pool

Papers

Antioxidant activity and stability of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.