Antioxidant

Antioxidants can be defined as any substance that significantly delays or prevents the oxidation of a substrate in an organism.

From: An Introduction to Aquatic Toxicology, 2014

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Antioxidants

F. Shahidi, in Handbook of Antioxidants for Food Preservation, 2015

Abstract

Antioxidants are used in food to protect it from deleterious effects of oxidation and are also employed as dietary supplements to neutralize the adverse effects of oxidative stress. Many of the natural antioxidants of interest are of plant origin and belong to the phenolic and polyphenolic class of compounds as well as carotenoids and antioxidant vitamins, among others. The activity of antioxidants and their mechanism of action is dictated by the structural features of the molecules involved, the system in which they are present as well as processing and storage conditions, among others. While much research has been carried out on natural sources of antioxidants, their widespread use is hindered by regulations, which only permits the use of those that have an RDI (required daily intake) such as vitamins. However, green tea, rosemary and other spices or their extracts thereof, and mixed tocopherols are often used in foods as flavouring agents or under other disguised forms to bypass these unwarranted regulatory issues.

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Antioxidants

S. Stanner, E. Weichselbaum, in Encyclopedia of Human Nutrition (Third Edition), 2013

Abstract

Antioxidants have the ability to scavenge free radicals in the human body and have been suggested to contribute to the protective effect of plant-based foods on diseases such as cardiovascular disease (CVD), cancer, and type 2 diabetes. However, evidence from supplementation studies using various antioxidants, including vitamin C, vitamin E, carotenoids, zinc, or selenium, does not support the hypothesis that antioxidants decrease risk of these diseases. Intervention studies highlight a lack of information on the safety of sustained intakes of moderate to high doses of micronutrient supplements and suggest that long-term harm cannot be ruled out, particularly in smokers.

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Synergistic interactions between antioxidants used in food preservation

Rong Tsao, in Handbook of Antioxidants for Food Preservation, 2015

13.4 Conclusion

Antioxidants used in food products, either natural or synthetic, can interact among themselves and result in synergistic, additive, and antagonistic interactions. Naturally occurring antioxidants, including antioxidant vitamins (e.g., vitamin C and vitamin E) and phytochemical antioxidants (e.g., polyphenols and carotenoids), when combined, can result in synergistic interactions, thus favor application in food systems. Advantages of using natural antioxidants, particularly combinations with synergistic outcomes, should be taken seriously; systematic investigations into the multifaceted interactions among natural and synthetic antioxidants, and with different food matrices, must be pursued.

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Bitter Kola (Garcinia kola) Seeds and Health Management Potential

B. Daramola, G.O. Adegoke, in Nuts and Seeds in Health and Disease Prevention, 2011

Mechanism of antioxidant action

Antioxidants can be divided into three groups by their mechanism: (1) primary antioxidants, which function essentially as free radical terminators (scavengers); (2) secondary antioxidants, which are important preventive antioxidants that function by retarding chain initiation; and (3) tertiary antioxidants, which are concerned with the repair of damaged biomolecules. Further information on the functionality of antioxidants can be found in a review by Giese (1996). As a sequel to the information given here, a follow-up study is ongoing in our laboratory to designate the class of antioxidants in GK seed. Such investigation should assist in providing information regarding appropriate applications of the bioactive components of GK seed.

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Volume 1

K.V. Peter, M.R. Shylaja, in Handbook of Herbs and Spices (Second Edition), Volume 1, 2012

1.4.3 Herbs and spices as a source of natural antioxidants

Antioxidants are added to foods to preserve the lipid components from quality deterioration. Synthetic antioxidants like butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT), propyl gallate (PG) and tert-butyl hydroquinone (TBHQ) are the ones commonly used. Due to the suspected action of these compounds as promoters of carcinogenesis, there is growing demand for natural anti-oxidants. Antioxidants also play a role in defence mechanisms of the body against cardiovascular diseases, cancer, arthritis, asthma and diabetes. Many herbs and spices are known as excellent sources of natural antioxidants, and consumption of fresh herbs in the diet may therefore contribute to the daily antioxidant intake. Phenolic compounds are the primary antioxidants present in spices, and a linear relationship exists between the total phenolic content and the antioxidant properties of spices. Essential oils, oleoresins and even aqueous extracts of spices possess antioxidative properties. The plants of the lamiaceae family are universally considered as important sources of natural antioxidants. Rosemary is widely used as antioxidant in Europe and the USA. Oregano, thyme, marjoram, sage, basil, fenugreek, fennel, coriander and pimento also possess antioxidant properties better than those of the synthetic antioxidant BHT. Important natural antioxidants and components responsible for the property are presented in Table 1.8.

Table 1.8. Antioxidants isolated from herbs and spices

Spice Antioxidants
Black pepper Phenolic amides, flavonoids
Ginger Gingerol
Tumeric Curcumin
Red pepper Capsaicin
Chilli pepper Capsaicin, capsaicinol
Clove Eugenol
Rosemary Carnosic acid, carnosol, rosemarinic acid, rosmanol
Sage Carnosol, carnosic acid, rosmanol, rosmarinic acid
Oregano Derivatives of phenolic acid, flavonoids, tocopherols
Thyme Carvacrol thymol, p-cymene, caryophyllene, carvone borneol
Summer savory Rosmarinic acid, carnosol, carvacrol, thymol
Marjoram Flavanoides
Allspice Pimentol
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Antioxidant Properties of Seaweed-Derived Substances

Ditte B. Hermund, in Bioactive Seaweeds for Food Applications, 2018

10.2 Antioxidants and Their Mechanisms

Antioxidants can be classified as primary or secondary antioxidants according to their antioxidant mechanisms. Multifunctional antioxidants are antioxidants that can exhibit both primary and secondary antioxidant properties.

The primary antioxidants, the so-called chain-breaking antioxidants, are able to react directly with free radicals by transforming them to more stable, nonradical products. Hence, primary antioxidants play an important role in lipid oxidation because they can react with the formed lipid radicals and convert them into nonradicals and thereby hinder further decomposition of the lipids (Decker, 2002).

Phenolic compounds with more than one hydroxyl group (OH) are efficient primary antioxidants due to their ability to donate H-atoms to free radicals, creating relatively unreactive phenoxyl radicals due to resonance stabilization. Synthetic phenolic compounds, like butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), are efficient chain-breaking antioxidants and widely used as food preservatives. Some naturally occurring phenolic compounds such as tocopherol, ascorbic acid, or caffeic acid are also used as chain-breaking antioxidants but are typically less efficient compared with the synthetic ones, but that again depends on the type of food product.

The secondary, or preventive, antioxidants work indirectly on limiting lipid oxidation. Several mechanisms including the chelation of transition metals, singlet-oxygen quenching (in photooxidation), and oxygen scavenging can be exhibited by these secondary antioxidants (Decker, 2002). Furthermore, some secondary antioxidants can work synergistically by regenerating primary antioxidants and thereby restore the antioxidant activity of primary antioxidants to ensure their continuous antioxidant activity. Ascorbic acid is an example hereof. Metal chelating ability of a secondary antioxidant is an important property for antioxidants in food systems because metal-induced lipid oxidation is pronounced in food products due to the presence of, e.g., iron. EDTA (ethylenediaminetetraacetic acid) is an example of an excellent metal chelating antioxidant used in the food industry (Haahr and Jacobsen, 2008).

The synthetic antioxidants, such as EDTA and BHT, are typically cheaper and can be easier to process than natural antioxidants. However, restrictions in the use of synthetic antioxidants have been enforced because of their health risks and toxicity (Branen, 1975; Linderschmidt et al., 1986). Hence there is a significant interest in and demand for replacing synthetic antioxidants with natural plant-based alternatives, not only due to safety issues but also due to increased consumer awareness and interest in natural products and the possible health benefits of natural antioxidants (Halliwell, 1996).

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Oxidative rancidity in nuts

F. Shahidi, J.A. John, in Improving the Safety and Quality of Nuts, 2013

9.6.4 Application of natural or synthetic antioxidants

Control of oxygen, by vacuum or using modified atmosphere packaging and oxygen scavengers such as glucose oxidase (Shahidi and Wanasundara, 1996) reduce lipid oxidation, especially when combined with the use of antioxidants and low temperature storage in the dark. Both natural and synthetic antioxidants are commonly added to foods to control lipid oxidation. Synthetic antioxidants approved for food use include phenolic compounds such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tertiary-butylhydroquinone (TBHQ) and non-phenolics such as ascorbic acid, ascorbyl palmitate and erythorbic acid (Lee et al., 1997). Natural antioxidants include carotenoids, ascorbic acid, amino acids and dipeptides, protein hydrolysates, phospholipids, tocols and other naturally occurring phenolic compounds (Kontogiorgis et al., 2005). The effectiveness of natural antioxidants from fruits, vegetables, spices, grains and herbs to combat lipid oxidation has been investigated (Madhujith and Shahidi, 2007; Liyana-Pathirana and Shahidi, 2006; Shahidi, 1997; Shahidi, 2000a). Rosemary and green tea extracts have been shown to have antioxidant activity in lipids and lipid containing foods (Shahidi, 2000b; He and Shahidi, 1997; Wanasundara and Shahidi, 1996). Most recently, Wang et al. (2011) found that naturally occurring carnosic acid exhibited stronger antioxidant activities oil than α-tocopherol and BHT, when supplemented in pine nut oil.

Antioxidants such as BHA, BHT and TBHQ are effective in preventing the oxidation of nuts and nut products such as peanut butter spread, almond spread, or nut oils by delaying the onset of rancidity and increasing shelf life. Various techniques are employed to add antioxidants to nuts and nut products such as:

Spraying a dilute antioxidant solution on nut surfaces, which is probably the easiest and most efficient way to deliver antioxidants to nuts. An antioxidant solution is typically diluted with vegetable oil, such as peanut oil, used in the roasting step. The antioxidant solution can be sprayed after the roasting step on nuts on a conveyor belt or in a spray tumbler. Spray tumbling will ensure the most complete coverage of antioxidant on the nut surface.

Addition to roasting oil. Antioxidants may be lost or destroyed during this step, as roasting temperatures will be relatively high.

Use of antioxidant treated salt or other condiments.

Addition to coating or glaze. Use of an edible protective coating containing antioxidant, such as a confectioner's glaze used to coat almonds or peanuts.

Use of antioxidant treated packaging materials.

Addition to nut oils.

The required amount of antioxidant is dissolved in a small amount of nut oil and the concentrated antioxidant portion is mixed throughout the entire bulk (Eastman Chemical Company, 2004).

FDA permits the addition of 200 mg/kg (ppm) total antioxidants (based on lipid content). However, this level of antioxidant on the surface may result in off-flavour development associated with antioxidants. Therefore, a level of 50–100 mg/kg is recommended. Shelf life studies of nuts should be conducted to determine the amount of antioxidant required to achieve the desired shelf life and whether any off-flavours result from the level of incorporated antioxidants.

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The functional role of herbal spices

M.R. Shylaja, K.V. Peter, in Handbook of Herbs and Spices, Volume 2, 2004

2.4.2 Antioxidant properties

Antioxidants are added to foods to preserve the lipid components from quality deterioration. Synthetic antioxidants such as butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT), propyl gallate (PG) and tert-butyl hydroquinone (TBHQ) are the commonly used synthetic antioxidants. Owing to their suspected action as promoters of carcinogenesis, there is growing interest in natural antioxidants.

Many herbal spices are known as excellent sources of natural antioxidants, and consumption of fresh herbs in the diet may therefore contribute to the daily antioxidant intake. Phenolic compounds are the primary antioxidants present in spices and there is a linear relationship between the total phenolic content and the antioxidant properties of spices. Essential oils, oleoresins and even aqueous extracts of spices possess antioxidative properties.

The plants of the Lamiaceae family are universally considered as an important source of natural antioxidants. Rosemary is widely used as an antioxidant in Europe and the USA. Oregano, thyme, marjoram, sage, basil, fenugreek, fennel, coriander and pimento also possess antioxidant properties, better than that of the synthetic antioxidant butylated hydroxy toluene. Phyto constituents such as carvacrol, thymol, rosmarinic acid and carnosic acid are responsible for the antioxidative property. Important natural antioxidants and components responsible for the property are presented in Table 2.5. Information on the relative antioxidative effectiveness (RAE) of various herbal spices is given in Tables 2.6 and 2.7.

Table 2.5. Antioxidants isolated from herbal spices

Spice Antioxidants
Rosemary Carnosic acid, carnosol, rosemarinic acid, rosmanol
Sage Carnosol, carnosic acid, rosmanol, rosmarinic acid
Oregano Derivatives of phenolic acid, flavonoids, tocopherols
Thyme Carvacrol thymol, p-cymene, caryophyllene, carvone, borneol
Summer savory Rosmarinic acid, carnosol, carvacrol, thymol
Marjoram Flavonoids
Allspice Pimentol

Table 2.6. Relative antioxidative effectiveness (RAE) of herbal spices evaluated as whole plant material in different substrates

Spice/herb Substrate RAE
Marjoram, rosemary, sage, coriander Lard Rosemary>sage>marjoram
32 different plant materials Lard Rosemary>sage>oregano>thyme
19 different plant materials Oil-in-water emulsion Sage>oregano
32 different plant materials Oil-in-water emulsion Allspice>rosemary
Allspice, savory, marjoram, coriander Sausage, water Allspice>savory>marjoram
15 different plant materials Sausage, water Sage>rosemary>marjoram>aniseed
12 different plant materials Ground chicken meat Marjoram>caraway>peppermint

Table 2.7. Relative antioxidative effectiveness (RAE) of herbal spice extracts

Substrate, conditions RAE
Lecithin emulsion, daylight, room temperature, 26 days Rosemary>sage
Lard, 50°C Rosemary>sage>marjoram
Chicken fat, 90°C Sage>rosemary
Methyl linoleate, 100°C Sage>deodorized rosemary> untreated rosemary
Lard, 75°C Oregano>thyme>marjoram> spearmint>lavender>basil
TGSO, 100°C Summer savory>peppermint> common balm>spearmint> oregano>common basil
Low-erucic rapeseed oil, 60°C, 23 days Sage>thyme>oregano
Methanol Oregano>cinnamon= marjoram>caraway
Minced chicken meat, 4°C and −18°C Caraway>wild marjoram
Raw pork meats, pretreated with NaCl, 4°C and −18°C Sage>basil>thyme
Microwave cooked pork patties treated with NaCl, −18°C Basil=thyme
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Oxidation and protection of nuts and nut oils

F. Shahidi, J.A. John, in Oxidation in Foods and Beverages and Antioxidant Applications: Management in Different Industry Sectors, 2010

8.4.2 Using natural or synthetic antioxidants

Control of oxygen availability is a critical factor in minimizing lipid oxidation. The oxygen level can be reduced by vacuum or using modified atmosphere packaging and by using oxygen scavengers such as glucose oxidase (Shahidi and Wanasundara, 1996). These precautions reduce lipid oxidation, especially when combined with the use of antioxidants and low temperature storage in the dark. Both natural and synthetic antioxidants are commonly added to foods to control lipid oxidation. Synthetic antioxidants approved for food use include phenolic compounds such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tertiary-butylhydroquinone (TBHQ) and non-phenolics such as ascorbic acid, ascorbyl palmitate and erythorbic acid (Lee et al., 1997). Natural antioxidants include carotenoids, ascorbic acid, amino acids and dipeptides, protein hydrolysates, phospholipids, tocols and other naturally occurring phe-nolic compounds (Kontogiorgis et al., 2005). The effectiveness of natural anti-oxidants from fruits, vegetables, spices, grains and herbs to combat lipid oxidation has been investigated (Shahidi, 1997; 2000a). Rosemary and green tea extracts have been shown to have antioxidant activity in lipids and lipid-containing foods (Shahidi, 2000b; He and Shahidi, 1997; Wanasundara and Shahidi, 1996).

Antioxidants such as BHA, BHT and TBHQ are effective in preventing the oxidation of nuts and nut products such as peanut butter spread, almond spread, or nut oils by delaying the onset of rancidity and increasing shelf-life. Various techniques are employed to add antioxidants to nuts and nut products and these may include:

1.

Spraying a dilute antioxidant solution on nut surfaces, which is probably the easiest and most efficient way to deliver antioxidants to nuts. An antioxidant solution is typically diluted with vegetable oil, such as peanut oil, used in the roasting step. The antioxidant solution can be sprayed after the roasting step on nuts on a conveyor belt or in a spray tumbler. Spray tumbling will ensure the most complete coverage of antioxidant on the nut surface.

2.

Addition to roasting oil. Antioxidants may be lost or destroyed during this step, as roasting temperatures will be relatively high.

3.

Use of antioxidant treated salt or other condiments.

4.

Addition to coating or glaze. Use of an edible protective coating containing antioxidant, such as a confectioner’s glaze used to coat almonds or peanuts.

5.

Use of antioxidant treated packaging materials.

6.

Addition to nut oils. The required amount of antioxidant is dissolved in a small amount of nut oil and the concentrated antioxidant portion is mixed throughout the entire bulk (Eastman Chemical Company, 2004).

FDA permits the addition of 200 mg/kg (ppm) total antioxidants (based on lipid content) while USDA allows combinations of antioxidants up to the same level on a fat weight basis but limits the use of a single antioxidant to 100 mg/kg of fat weight. However, this level of antioxidants on the surface may result in off-flavour development associated with antioxidants. Therefore, a level of 50100 mg/kg is recommended. Shelf-life studies of nuts should be conducted to determine the amount of antioxidant required to achieve the desired shelf-life and whether any off-flavours would result from the level of incorporated antioxidants. Figure 8.4 demonstrates the effectiveness of BHA/BHT in improving the shelf-life of various nut products as compared to the control without antioxidants (Eastman Chemical Company, 2004). Thus, use of natural or synthetic antioxidants can minimize oxidation in nuts and nut oils.

Fig. 8.4. Effect of BHA/BHT treatments on the stability as reflected in the extension of storage time of nut kernels stored at 62 °C.

Adapted from Eastman Chemical Company.
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The Role of Oxidative Stress in Endometriosis

Aditi Mulgund MD, ... Ashok Agarwal PhD, in Handbook of Fertility, 2015

Antioxidants

Antioxidants are a defense mechanism produced by the body to neutralize the effects of ROS. They can be enzymatic and nonenzymatic. Nonenzymatic sources of antioxidants include vitamin C, vitamin E, selenium, zinc, beta carotene, carotene, taurine, hypotaurine, and glutathione. Enzymatic antioxidants include SOD, catalase, glutaredoxin, and glutathione reductase [64]. However, as the body ages, antioxidant levels decline, resulting in a disruption in the balance between antioxidants and prooxidant molecules. This results in the generation of oxidative stress and in turn, overrides the scavenging capacity by antioxidants either due to the diminished availability of antioxidants or excessive generation of ROS. Therefore, supplementation with oral oxidants may help to alleviate oxidative stress and its contribution to the pathogenesis of obstetrical disease such as endometriosis [65]. Only the most relevant antioxidants beneficial to endometriosis will be discussed.

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