The effect of ozone was studied on the peroxidase activity from various compartments of Sedum album leaves (epidermis, intercellular fluid, residual cell material, and total cell material). The greatest increase following a 2-hour ozone exposure (0.4 microliters O/sub 3/ per liter) was observed in extracellular peroxidases. Most of the main bands of peroxidase activity separated by isoelectric focusing exhibited an increase upon exposure to ozone. Incubation experiments with isolated peeled or unpeeled leaves showed that leaves from ozone-treated plants release much more peroxidases in the medium than untreated leaves. The withdrawal of Ca/sup 2 +/ ions reduced the level of extracellular peroxidase activity either in whole plants or in incubation experiments. This reduction and the activation obtained after addition of Ca/sup 2 +/ resulted from a direct requirment of Ca/sup 2 +/ by the enzyme and from an effect of Ca/sup 2 +/ on peroxidase secretion. The ionophore A23187 promoted an increase of extracellular peroxidase activity only in untreated plants. The release of peroxidases by untreated and ozone-treated leaves is considerably lowered by metabolic inhibitors (3-(3,4-dichlorophenyl)-1,1-dimethylurea and sodium azide) and by puromycin.

Peroxidase release induced by ozone in Sedum album leaves: involvement of Ca/sup 2 +/. [Sedum album]

Effects of anthocyanin-rich purple and black eggplant extracts on the physical, antioxidant and pH-sensitive properties of chitosan film

In this review, the concept of phenolic antioxidants, mechanisms of action, and applications have been reviewed. Phenolic compounds (PCs) acts as an antioxidant by reacting with a variety of free radicals. The mechanism of antioxidant actions involved either by hydrogen atom transfer, transfer of a single electron, sequential proton loss electron transfer, and chelation of transition metals. In foods, the PCs act as antioxidants which are measured with several in vitro spectroscopic methods. The PCs have been found in milk and a wide range of dairy products with sole purposes of color, taste, storage stability, and quality enhancement. The role of PCs in three types of food additives, that is, antimicrobial, antioxidant, and flavoring agents have been critically reviewed. The literature revealed that PCs present in a variety of foods possess several health benefits such as antibacterial, antihyperlipidemic, anticancer, antioxidants, cardioprotective, neuroprotective, and antidiabetic properties. PRACTICAL APPLICATIONS: Phenolic compounds are strong antioxidants and are safer than synthetic antioxidants. The wide occurrence in plant foods warranted continuous review applications. This review, therefore, presented an updated comprehensive overview of the concept, mechanism, and applications of phenolic antioxidants in foods.

Concept, mechanism, and applications of phenolic antioxidants in foods.

Background Lipid oxidation is one of the main causes of food spoilage. It can be delayed by the addition of antioxidants to food or by using vacuum or modified atmosphere packaging. A recent approach is the application of antioxidants in active packaging. Scope and approach The scope of this review is to present and update all information about the incorporation of natural antioxidants in edible and active films and coatings. Natural antioxidants can replace chemical additives and are preferably accepted by the consumers. Their effect on the barrier, mechanical and antioxidant properties of the various films (chitosan, cellulose derivatives gelatin etc.) are discussed. The ability to delay food oxidation is examined in relation to the active components. Key findings and conclusions Water or ethanol extracts from several herbs (rosemary, oregano, tea), berries, or plant by-products increased the total phenolic content and the antiradical activity of the films and proved efficient in delaying the oxidation of fish and meat products. Also, a protective activity was observed from the essential oils that were rich in carvacrol or thymol. The barrier properties of the films were positively affected, due to interactions between the active groups of the additive (e.g. polyphenols) and the film matrix. On the contrary, hydrophilic additives increased water vapor and oxygen permeability. The mechanical properties were in most cases adversely affected. Results are promising and further research on the release of antioxidant compound into food, the effect on sensorial properties, and application to other lipid foods may encourage practical application.

Edible and active films and coatings as carriers of natural antioxidants for lipid food

Fruits and vegetables are essential for human nutrition, delivering a substantial proportion of vitamins, minerals, and fibers in our daily diet. Unfortunately, half the fruits and vegetables produced worldwide end up as wastes, generating environmental issues caused mainly by microbial degradation. Most wastes are generated by industrial processing, the so-called by-products. These by-products still contain many bioactive compounds post-processing, such as macronutrients (proteins and carbohydrates) and phytochemicals (polyphenols and carotenoids). Recently, the recovery of these bioactive compounds from industry by-products has received significant attention, mainly due to their possible health benefits for humans. This chapter focuses on the bioactive potential of fruit and vegetable by-products with possible applications in the food industry (functional foods) and in the health sector (nutraceuticals).

Bioactive potential of fruit and vegetable wastes.

https://krishi.icar.gov.in/jspui/bitstream/123456789/42874/1/Antioxidant%20activity%20and%20phenolic%20content%20in%20genotypes%20of%20Indian%20jujube%20%28Zizyphus%20mauritiana%20Lamk.%29%20_%20Elsevier%20Enhanced%20Reader.pdf

Antioxidant activity and phenolic content in genotypes of Indian jujube (Zizyphus mauritiana Lamk.)

Evaluation of bioactive properties of Indian carrot (Daucus carota L.): A chemometric approach

Eggplant has limited shelf-life of only 3 days under ambient storage conditions. The functional quality of carnauba wax (CW) is assessed with various additives for shelf-life related attributes in eggplant during ambient storage (20 ± 1 °C and RH 52–54%) in both unpackaged and packaged in 35μ polypropylene pouches. Minimum decrease (8.56 N-6.92 N and 8.56 N-5.63 N) in firmness was recorded in Poly ethylene glycol (PEG) and 0.5% Sodium alginate (SA) in diluted (1:4) CW emulsion (T 2 ) while maximum decrease (8.56 N-5.54 N and 8.56 N-3.57 N) in control (T 4 ) packaged and unpackaged eggplants after 12 days of storage, respectively. Maximum antioxidant activity (67.63 and 51.52 μmol Trolox equivalent antioxidant capacity (TEAC)/100 g FW) was observed in T 2 treatment and minimum antioxidant activity (23.61 and 20.60 μmol TEAC/100 g FW) in control fruits in packaged and unpackaged respectively after 12 days. The minimum decrease (2.64–2.20 and 2.64–2.24) μmol tetraguaiacol (TG)/min/100 g FW) of peroxidase activity was recorded in T 2 treated fruits in packaged and unpackaged eggplant respectively and maximum decrease (2.64–1.37 and 2.64–1.63 μmol TG/min/100 g FW) was obtained in control unpackaged and packaged eggplant respectively after 12 days. Packaged eggplant treated with PEG and SA in CW emulsion remained acceptable upto 12 days.

Tanmay Kumar Koley

Papers

Antioxidant activity and phenolic content in genotypes of Indian jujube (Zizyphus mauritiana Lamk.)

Evaluation of bioactive properties of Indian carrot (Daucus carota L.): A chemometric approach

Carnauba wax-based edible coating enhances shelf-life and retain quality of eggplant (Solanum melongena) fruits

Synergistic effects of nutmeg and citrus peel extracts in imparting oxidative stability in meat balls

High resolution LC-MS characterization of phenolic compounds and the evaluation of antioxidant properties of a tropical purple radish genotype