Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

This article is a review of the fundamental chemistry of the tocopherols and tocotrienols relevant to their antioxidant action. Despite the general agreement that α-tocopherol is the most efficient antioxidant and vitamin E homologuein vivo, there was always a considerable discrepancy in its “absolute” and “relative” antioxidant effectivenessin vitro, especially when compared to γ-tocopherol. Many chemical, physical, biochemical, physicochemical, and other factors seem responsible for the observed discrepancy between the relative antioxidant potencies of the tocopherolsin vivo andin vitro. This paper aims at highlighting some possible reasons for the observed differences between the tocopherols (α-, β-, γ-, and δ-) in relation to their interactions with the important chemical species involved in lipid peroxidation, specifically trace metal ions, singlet oxygen, nitrogen oxides, and antioxidant synergists. Although literature reports related to the chemistry of the tocotrienols are quite meager, they also were included in the discussion in virtue of their structural and functional resemblance to the tocopherols.

The chemistry and antioxidant properties of tocopherols and tocotrienols

Natural antioxidants from residual sources.

Antioxidant Potential of Ferulic Acid

As the continues to improve the nutritional content of their products, challenges in prevention of rancidity have increased due to the presence of more polyunsaturated fatty acids. In addition, consumer demand for all natural foods has limited the use of traditional methods to control lipid oxidation such as synthetic antioxidants and hydrogenation. To overcome these challenges a better understand the mechanisms of lipid oxidation are needed so that novel antioxidant technologies can be developed. Lipids in foods often exist as dispersions stabilized by emulsifiers that provide physical stability. Food emulsions contain an oil-water interface that has major impact on the lipid oxidation pathways by influencing the location and reactivity of prooxidative transition metals, lipid hydroperoxides, minor lipid components, free radical scavengers and metal chelators. Understanding how the physical properties of the lipid–water or lipid–air interface in food dispersions impacts oxidation chemistry has lead to new strategies to create lipid structures that slow down the development of rancidity by decreasing interaction between lipids in the emulsion droplet core with prooxidants and oxygen as well as increasing antioxidant concentrations at the site of oxidation.

Mechanisms of lipid oxidation in food dispersions

Individual and combined effects of ascorbic acid andδ-tocopherol on the autoxidation of fish oil have been evaluated with the induction period monitored by Rancimat. The antioxidative efficiency of them was found to increase with increasing concentration.δ-Tocopherol and ascorbic acid acted highly synergistic with each other. Whenδ-tocopherol content was varied at a fixed content of ascorbic acid, the synergistic efficiency was generally 100% or more. On the other hand, when ascorbic acid content was varied at a fixed content ofδ-tocopherol, the synergistic efficiency rose sigmoidally with increasing concentration. We concluded that at least 0.01–0.02% ascorbic acid is required to obtain a considerable synergistic effect withδ-tocopherol in stabilizing fish oil.

Synergistic antioxidative effects of tocopherol and ascorbic acid in fish oil/lecithin/water system

A method for inhibiting the oxidation of edible oils and fats by forming a reverse micelle by admixing a mixture of an aqueous solution containing a water-soluble antioxidant with a surfactant and said oils or fats.

Method for the inhibition of oxidation of edible oils utilizing a fat soluble anti-oxidant and a water soluble anti-oxdant in a reverse micelle system

Antioxidative effects of ascorbic acid and δ-tocopherol on the oxidation of sardine oil stored at 30°C in the dark has been investigated. It was found from phase diagrams and peroxide values of fish oil/lecithin/water systems that the desirable levels of lecithin and water to solubilize ascorbic acid in the oil were 0.3% (w/w) and 0.1% (w/w), respectively. When ascorbic acid (0.02%) and δ-tocopherol (0.4%) were used together, the induction period of fish oil could be lengthened 22-fold, due to their synergism. They could inhibit the production of carbonyl and volatile compounds and oxidative polymerization.

Solubilization of vitamin C in fish oil and synergistic effect with vitamin E in retarding oxidation

알칼리 수산화물이 용해되어 있는 에탄올을 사용하여 어유를 비누화시키고 이를 냉각 여과함으로써 ${\omega}-3$ 고도불포화지방산 특히, EPA와 DHA가 농축된 지방산 농축물을 얻을 수 있었다. 정어리유와 농축물의 지방산 비교 분석한 결과 지방산 분자의 이중결합 수 또는 탄소사슬 길이보다는 탄소사슬 길이에 대한 이중결합 수의 비율이 에탄올에 대한 지방산 나트륨염의 용해도를 결정짖는 보다 중요한 인자라는 점을 알수 있었다. 비누화 반응의 용매인 에탄올 내의 물함량은 분리효율에 커다란 영향을 끼쳤는데 물함량이 낮아질수록 농축물 내의 EPA 및 DHA 함량과 이들의 수율이 증가되는 경향이었다. 한편, 비누화된 용액을 결정화시킬 때의 냉각온도 및 냉각과정은 공정의 효율에 큰 영향을 끼치지 않았다. 무수 에탄올을 사용하고 비누화된 용액을 $10^{\circ}C$ 로 급속 냉각하였을때 EPA와 DHA함량이 원료 정어리유의 14.2%와 10.7%에서 각각 34.1%와 27.8%로 증가된 PUFA농축물을 84.5%의 수율로 얻을 수 있었다. 【Fatty acid fraction rich in ${\omega}-3$ polyunsaturated fatty acids ( ${\omega}-3$ , PUFA), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) could be obtained by saponification of fish oil in ethanol containing alkali hydroxide followed by cooling and filtration of the resultant solution. Fatty acid compositions of fish oil and the concentrates suggest that the ratio of number of double bonds to carbon number in a fatty acid molecule is a more important factor than the degree of unsaturation or the chain length in determining the solubility of fatty acid salts in ethanol. Water content in ethano1 affected significantly the efficiency of the separation with respect to yield and content of EPA and DHA in the concentrates; the lower the water content, the higher the efficiency. It was, however, influenced little by cooling procedure and temperature which the saponified solution experienced during the crystallization. Under an optimal condition, the contents of EPA and DHA in the concentrate increased by 2.4 and 2.5 times, respectively, as compared with those in sardine oil.】

Separation of EPA and DHA from fish oil by solubility differences of fatty acid salts in ethanol

In order to study the effect of modified atmosphere storage on extending shelf life of mushrooms, oyster mushroom and Shiitake were wrapped with polyethylene film (PE, ), and stored at . Mushrooms packed with conventional hardboard box (4kg) lost marketability within days due to weight loss, shrinkage, browning, spore formation and/or mycellium growth. PE-packing could prevent or retard the deterioration of the mushrooms in the aspects of appearance, texture, discoloration, and microbial contamination. This situation can be best characterized by the reduced respiration rate resulted from the elevated level of carbon dioxide and the reduced level of oxygen in the bag. Although the appearance of the oyster mushroom was maintained for one month, its shelf life was limited to 15 days because of tissue softening. Discoloration of the pileus of shiitake mushroom appears to be the most important factor to determine its marketability. For example, extension of shelf life of Dongo was limited to 15 days, principally due to the browning of the pileus. Shelf life of Hawgo whose color of the pileus changed little over the experimental period, however, could be extened to more than one month.

Dae-Seok Han

Papers

Synergistic antioxidative effects of tocopherol and ascorbic acid in fish oil/lecithin/water system

Method for the inhibition of oxidation of edible oils utilizing a fat soluble anti-oxidant and a water soluble anti-oxdant in a reverse micelle system

Solubilization of vitamin C in fish oil and synergistic effect with vitamin E in retarding oxidation

Separation of EPA and DHA from fish oil by solubility differences of fatty acid salts in ethanol

Modified Atmosphere Storage for Extending Shelf Life of Oyster Mushroom and Shiitake