Application of Natural Antioxidants in Meat and Meat Products-A Review

Presently consumers are demanding more natural foods, obliging the industry to include natural antioxidants in foods. Antioxidants can act as metal chelators and free radical or oxygen scavengers, which can slow the progression of lipid oxidation. Lipid oxidation may have negative effects on the quality of meat and meat products, causing changes in sensory attributes such as colour, texture, odour and flavour, and nutritional quality. Several synthetic antioxidants have been used to successfully prevent lipid oxi dation in the meat industry, but consumers are concerned about the health risks related to consumption of some synthetic antioxidants. Therefore, there has been a growing interest in natural antioxidants. Nowadays, compounds obtained from natural sources such as grains, oilseeds, spices, fruit and vegetables have been investigated to decrease the lipid oxidation. Recent investigations have been directed towards the identification of natural antioxidants from various plant sources. Antioxidants work as functional additives by providing health promoting effect in human body system. This article evaluates the efficacy of various natural anti oxidants on the quality and shelf life enhancement of meat and meat products during processing, storage, distribution till it reach-es to consumer. The potential effects of natural antioxidants that are widely used in meat and meat products are also discussed.


Introduction
Meat is rich source of proteins, lipids, vitamins and minerals.Meat products are spoiled by two major causes: microbial growth and chemical deterioration.The most common form of chemical deterioration is oxidative rancidity as lipids are integral components of muscle.The oxidative rancidity occurred in meat and meat products can vary greatly, ranging from extensive flavor changes, color losses and structural damage on proteins [1] to a subtler "loss of freshness" that discourages repeat purchases by consumers.Lipid oxidation leads to the formation of numerous other compounds which have adverse effects on the quality attributes and nutritive value of meat products [2] and this process frequently limits the shelf-life of processed meat.Oxidation is a well-known non-microbial cause of quality loss in meat.Oxidative stress occurs due to uneven generation of free radicals Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) which triggers oxidative and/or nitrosamine stress and damage of macromolecules including the lipid and protein fractions.Antioxidants are compounds that are capable of donating hydrogen (H • ) radicals for pairing with other available free radicals to prevent the propagation reaction during the oxidation process.This effectively minimizes rancidity, retards lipid oxidation, without any damage to the sensory or nutritional properties, resulting in maintaining quality and shelf-life of meat products.Antioxidants reduces or prevent the oxidation and have ability to counteract damaging effects of free radicals in tissues and thus are believed to protect against cancer, atherosclerosis, heart disease and several other diseases [3].The use of natural antioxidants has the advantage of being more acceptable by the consumers as these are considered as non-chemical.In addition, they don't require safety tests before being used.Moreover, natural antioxidants are reported to be more powerful than the synthetics.The demand for natural antioxidants has recently increased because of the toxicity and carcinogenicity of synthetic antioxidants [4].Many natural plant extracts contain primarily phenolic compounds, which are potent antioxidants [5].Including antioxidants in the diet has beneficial effects on human Volume 2018; Issue 03 Food Nutr J, an open access journal ISSN: 2575-7091 health because they protect the biologically important cellular components, such as DNA, proteins, and membrane lipids, from Reactive Oxygen Species (ROS) attacks [6].Recently, consumers have rejected synthetic antioxidants because of their carcinogenicity [7].Many herbs, spices, and their extracts have been added in a variety of foods to improve their sensory characteristics and extend shelf-life [8].In this review natural antioxidants that are widely used in meat products and their effects on meat & product's quality were evaluated.

Mechanism of Lipid Oxidation in Meat and Meat Products
Lipid oxidation can take place at 3 stages: at pre-slaughter (live muscle), during slaughtering (conversion of muscle to meat) and after slaughtering (processing and storage).In live animals, intrinsic factors are available that can control the oxidation reaction in muscular tissues, such as enzymes (superoxide dismutase, catalase etc.) and certain proteins and their mechanisms (transport proteins), or oxidative reaction-breaking antioxidants (vitamin E and C) [9].After slaughtering, these factors lose their antioxidative potential due to various post-slaughter conditions, such as anaerobic environment, presence of prooxidants (P 0 ), and lack of enzymatic antioxidative mechanisms [10].Hemoglobin and myoglobin, which are also considered as prooxidants [11], along with other processing parameters, result in lipid oxidation during processing and storage of meat and meat products.Lipid oxidation is described as an oxygen-dependent, deterioration of saturated and unsaturated fatty acids.This modification of fatty acid is principally carried out by an autocatalytic mechanism of free radicals, called auto-oxidation and consisting of 3 phases: initiation, propagation and termination.Lipid oxidation in muscle foods is initiated in the highly unsaturated phospholipids fraction of subcellular bio-membranes, unsaturated portions of fatty acid esters (triglycerides or phospholipids) react with molecular oxygen to form peroxides, hydroperoxides and carbonyl compounds [12].The hydroperoxides are unstable and are reductively cleaved in the presence of trace elements to produce new free radicals and nonradical compounds including aldehydes, ketones, alcohols and acids that cause the off odor, off flavor, change in nutritive value and safety of muscle foods.

Classification I
Primary antioxidants: Also called as chain-breaking antioxidative compounds react directly with lipid radicals and inhibit or retard oxidation by scavenging free radicals by donation of hydrogen atoms or electrons, which converts them to more stable products.

Secondary antioxidants:
They reduce the rate of oxidation by different mechanism of action, including binding of metal ions (Fe 2+ , Fe 3+ , and Cu 2+ ), by scavenging oxygen, by converting hydroperoxides to non-radical species, by absorbing UV radiation or deactivating singlet oxygen, by inhibiting enzymes [13].Some natural phenolic compounds function as both primary and secondary antioxidants.
Endogenous antioxidants: These are produced in the body/ muscles due to various metabolic reactions and provide innate resistance to the meat for oxidation.It varies from species to species, breed to breed and animal to animal.These includes non-enzymes (carnosine, tocopherol, ascorbic acid), formed antioxidants.

Classification III
Natural antioxidants: Ingredients widely present in natural sources which exhibit antioxidative potential in a food model system are considered as natural antioxidants.Phenolic compounds present in plants have a high antioxidant activity through three mechanisms: free-radical scavenging activity [14], transition-metal-chelating activity [15], and/or singlet-oxygen quenching capacity [16].

Mechanism of Action of Natural Antioxidants
The majority of natural antioxidants are phenolic compounds, and the most important are the tocopherols, flavonoids, and phenolic acids.The major antioxidative phenolics are: phenolic acids, phenolic diterpenes, flavonoids, and volatile oils.Phenolics present in the natural antioxidants have strong H • -donating activity [17] or have high radical-absorbance capacity.Decreasing localized oxygen concentrations; preventing chain initiation by scavenging initiating radicals; decomposing peroxides, chainbreaking to prevent continued hydrogen abstraction by active radicals.Some phenolics prevent the formation of free radicals and propagation of ROS, whereas, other scavenge free radicals and chelate prooxidants (transition metals) [18].Phenolic acids trap free radicals; flavonoids scavenge free radicals and chelate metals (Fe 2+ , Fe 3+ , and Cu 2+ ) as well.

Use of Natural Antioxidants in Meat Products
Use of natural antioxidants in meat and meat products is presented in Table 1

Herbs, Spices and Teas
The use of plant derived nutraceuticals may allow meat processors to develop novel meat products with enhanced nutritional and health benefits, improved shelf-life, quality and profile.
Rosemary: Rosemary (Rosmarinus officinalis L.) is a popular herb belonging to the Lamiaceae family with high antioxidant activity.The antioxidant activity of rosemary extracts has been associated with the presence of several phenolic diterpenes such as carnosic acid, carnosol, rosmanol, isorosmanol, rosmariquinone, rosmaridiphenol and rosmary-diphenol which break free radical chain reactions by hydrogen donation [45,46] reported that rosemary extracts improved the color stability of turkey rolls in addition to their inhibition of lipid oxidation.[47] reported the addition of rosemary in refrigerated turkey sausage as an effective way to suppress lipid oxidation and to increase the shelf life.[48] observed that clove, rosemary and cassia bark extracts to be highly effective antioxidants in cooked pork patties as they inhibited lipid oxidation and stabilized red colour (myoglobin) during refrigerated storage.
Sage: Sage (Salvia officinalis) is a common aromatic and medicinal plant.The antioxidant properties were found to be related with the presence of phenolic compounds such as rosmarinic acid, carnosic acid, salvianolic acid and its derivatives carnosol, rosmanol, epirosmanol, rosmadial, isorosmanol, galdosol and methyl carnosate [49][50][51].Major Oregano and sage essential oils added to beef and pork meat reduce oxidation during refrigeration and antioxidant activity of sage oil more potent in cooked meat than in raw meat [20].
Oregano: Oregano (Origanum vulgare) is well known for its antioxidant activity contains more than 30 compounds with carvacrol and thymol being responsible for its antioxidant activity [52].[20] reported lowered levels of oxidation after 12 days of refrigerated storage of pork and beef added with 3% oregano oil.Dietary incorporation of oregano, rosemary, and sage essential oils can retard lipid oxidation (MDA formation) in meat during refrigerated and frozen storage.Lower MDA formation in dietary oregano essential oil treatments are probably the result of the presence of oregano antioxidant compounds, which might be absorbed into the circulatory system after ingestion, distributed, and retained in muscle and other tissues [53].The higher color parameters of meat from lambs fed with oregano essential oil supplementation [53].Active films containing oregano essential oil can reduce the growth of total flora and pseudomonas, thus inhibiting the growth of lactic acid bacteria in beef [54].Moreover, oregano-based films were effective against Salmonella typhimurium and E. coli O157:H7 inoculated in beef muscle slices [55].
Garlic: Garlic is used traditionally as a flavour enhancer in foods and has medicinal properties due to wide spectrum of actions such as antibacterial, antiviral, antifungal and antiprotozoal.It also has beneficial effects on the cardiovascular and immune systems [56].Garlic demonstrated effective antioxidant activity in vivo and in vitro [57] due to organ sulphur compounds and their precursors, allicin, diallyl sulphide and diallyl trisulfide [58,59]  Onion (Allium cepa L.): Onion is much valued for its flavouring components and has high flavonoids, quercetin (284-486 mg/ kg) which act as antioxidant in cooked ground turkey [62] and in cooked ground lamb [63], oven-cooked turkey breast.
Mint (Mentha spicata L): Spearmint or garden mint, family Lamiaceae (Labiatae) is often used as a flavour enhancer, is a rich source of polyphenolic compounds with strong antioxidant properties [64,22].Mint leaves contains eugenol, caffeic acid, rosmarinic acid and alpha-tocopherol.Raw ground pork meat treated with mint leaf extract showed a significantly lower TBA value than control during refrigerated storage at 4±1 0 C [22].
Colorifico: Colorifico is a spice consisting essentially of a mixture of annatto (Bixa orellana) and corn flour.Colorifico has higher capacity of scavenging free radicals than onion and coriander [65].
[66] reported that the addition of colorifico (0.4 g/100 g) to minced chicken meat was an alternative for enhancing chicken colour and also minimising lipid oxidation during storage of grilled patties at 18 0 C for 120 days.

Cinnamon:
The antioxidant activity of cinnamon is due to the scavenging capacity of cinnamaldehyde which can scavenge 2, 2-Diphenyl-1-Picryl Hydrazyl Radical (DPPH) and the hydroxyl radical (OH radical).The scavenging of DPPH and OH radicals by cinnamon oil is attributed to the hydrogen donating capacity of the phenolic component of cinnamic oil [67].Essential oil of cinnamon reduces the TBARS values in minced chicken meat during 10 days refrigerated storage [68].Deodorized aqueous extract (CinDAE) was evaluated for its antioxidant potential in chicken meatballs under chilled conditions [69] and antioxidant effect of Cinnamomum Zeylanicum Essential Oil (CZEO) in cooked sausage was evaluated by [70] and it was concluded that 20 and 40 ppm CZEO treatment resulted in lower peroxide and TBARS values than the control (P < 0.05), without affecting the sensory characteristics of the meat samples.
Thyme: Thyme contains phenolic acids: caffeic acid, ferulic acid, gallic acid, rosmarinic acid, volatile compounds-thymol, phenolic diterpenes and flavonoids-luteolin. [71] reported the antioxidant effect of thyme and balm essential oils in fresh chicken breast meat stored at 4 °C for 3 weeks.It was shown that thyme reduced DPPH radical formation, lipid peroxidation and the deterioration of sarcoplasmic proteins, helping to preserve the meat even after 2 wk of storage.Thyme essential oil exhibited very strong freeradical scavenging ability and inhibited Fe 2+ /ascorbate and Fe 2+ / H 2 O 2 induced lipid oxidation [72].
Green tea leaf extracts: Green tea leaf extracts are becoming increasingly important as a functional food in human diet because of their high polyphenol contents.The antioxidative property of green tea extract is due to the presence of Tea Catechins (TC), Epicatechins (EC), Epigallocatechin (EGC), epigallocatechin gallate (EGCG) and Epicatechin Gallate (ECG) [73].These compounds have high affinity for lipid bilayers of muscle and the radical scavenging activity which prevent lipid oxidation and also have antibacterial action [74].The tea catechins and other polyphenols are free radical scavengers, metal chelators, inhibitors of transcription factors, and enzymes as reported by [75] in frozen broiler meat by adding rosemary, echinacea, green tea extracts and ascorbic acid.[76] in refrigerated luncheon roll meat added green tea extract and thyme oil.TC can also reduce the formation of peroxides more effectively than alpha-tocopherol or BHA in porcine lard and chicken fat [77] and fish muscle model system [78].

Rooibos tea extract:
[79] investigated that the addition of 0.25 % (RBTE) rooibos tea extract resulted in improved lipid stability and sensory attributes of the droewors.The unfermented green rooibos inclusion considerably lowered the TBARS content of ostrich patties; and the fermented form (0.5% and 1%) was also effective in delaying lipid oxidation in ostrich salami up to 15 day of ripening.
Cocoa leaves: These are effective antioxidants similar to green tea polyphenol.These can be used as extract and it has lower astringency and bitterness [80].Therefore, can be used in higher concentrations, for increased effectiveness as antioxidant.
Marjoram: Marjoram (Origanum majorana L.) essential oil inhibits formation of primary oxidation compounds (conjugated dienes) by 50% and the secondary generation of oxidation products (linoleic acid) by 80% in a model system [81].The purified active compound isolated from marjoram, T3b, a phenolic substance, is a better superoxide anion radical scavenger and have epigallocatechin gallate, quercetin, epicatechin [82] and destroys the superoxide anion by converting it to H 2 O 2 .
Bamboo leaves: Dried bamboo leaves powder are traditionally used as antioxidant due to flavones, lactones, phenolic acids [84], which impairs chain reaction and chelate transitional metal ions, and therefore, can be used as primary and secondary antioxidant.Furthermore, bamboo leaves powder can help in the partial or complete replacement of the nitrites in cured meat.It inhibits the synthesis of N-nitrosamine, and has antibacterial, bacteriostatic, deodorizing, aroma enhancing functions.

Fruits and Vegetables
Plum derived ingredients: Plum-derived food ingredients have been reported to function as antioxidants, antimicrobials, fat Volume 2018; Issue 03 Food Nutr J, an open access journal ISSN: 2575-7091 replacers, and flavourings.Due to principal phytochemicals in dried plums viz., phenolic acid derivatives, flavonoids and coumarins [85] including neoclorogenic, chlorogenic and cryptochlorogenic acid.Dried plum puree at 3% or higher level has been shown to retard lipid oxidation in precooked pork patties [86] and 2.5% fresh plum juice concentrate or dried plum juice concentrate in precooked beef roasts [87].
Pomegranate: Pomegranate fruit parts have bioactive compounds like tannins, anthocyanins, flavonoids and other phenolic compounds which prevent low-density lipoprotein oxidation, prostate cancer, platelet aggregation and various cardiovascular diseases [88].[28] compared the efficacy of pomegranate juice, pomegranate rind powder extract and BHT as antioxidants in cooked chicken patties and observed that the lipid oxidation inhibition effect was highest in refrigerated chicken patties incorporated with pomegranate rind powder.

Avocado:
The antioxidative effects of the peel, pulp, and seed from 2 avocados (Persea americana Miller) varieties ("Hass" and "Fuerte") were studied in pork meat patties [89].It was reported that the avocado extracts protected meat lipids and proteins against oxidation as peels and seeds were rich in catechins, procyanidins, and hydroxycinnamic acids, and the pulp was particularly rich in hydroxybenzoic acid, hydroxycinnamic acid, and procyanidins.
Cherry: Cherry fractions contain phenolic compounds such as flavones, isoflavones, anthocyanins, anthocyanidins and phenolic glycosides.[90] investigated that thiobarbituric acid-reactive substances values and cholesterol oxidation for raw and cooked ground beef patties containing cherry tissue were significantly lower and the formation of mutagenic/carcinogenic HAAs during frying of the patties was inhibited by components in the cherry tissue.

Tomato:
The main active compound of tomatoes is lycopene.It is highly effective antioxidant owing to its ability to act as free radical scavenger and has the highest singlet oxygen quenching rate than all carotenoids tested in biological system [91].[92] confirmed that antioxidant effect of tomato paste in beef during refrigerated storage, beef patties [93], dry tomato peel in dry fermented sausage [94] could be successfully used up to a level of 12% without any negative effect on the processing and quality characteristics of the product throughout its storage.
Banana and Sapodilla: Banana and Sapodilla/ Chikoo peel extracts significantly reduced the lipid oxidation in chicken meat during refrigerated storage [95].

Grape Seed Extract (GSE):
Grapes are used in various forms as seed extract, dietary fiber, pomace, grape wine etc. Grape Seed Extract (GSE) rich in proanthocyaninidins in the form of oligomers and polymers of polyhydroxy flavan-3-ols such as catechin and epicatechin [96].Antioxidant effect of GSE evaluated on cooked beef [97], turkey patties and refrigerated turkey meat [98].GSE shows reduced lipid oxidation effectively as reported in beef, chicken, and turkey during refrigerated storage [99] in both raw and cooked meat systems during refrigerated and frozen storage, in raw and cooked pork patties [100] and in cooked pork meatballs during 16-day aerobic retail refrigerated storage conditions [101].Grape pomace is a concentrate of grape seeds, stems and peel.This is a rich source of flavonoids including monomeric phenolic compounds, such as catechins, epicatechin and epicatechin-3-Ogallate and dimeric, trimeric and tetrameric procyanidins [102].It can be used as dietary supplement in broiler chickens to oxidative resistance of poultry meat [103].Grape Antioxidant Dietary Fiber (GADF) effectively used (0.5, 1, 1.5 and 2% concentrations) in raw and cooked chicken breast hamburger by [104] during refrigerated storage.GADF addition resulted in reduction in lightness and yellowness and an increase in redness in raw and chicken hamburgers without affecting the acceptability of the products.Grape seed extract@ 0.1 % had excellent antioxidant properties, improved microbiological quality and had superior sensory scores compared to control and butylated hydroxyl anisole during refrigerated storage of restructured mutton slices under aerobic and vacuum conditions [105].
Citrus extract: Citrus fruit essential oils are the most widely used essential oils in the world [106] contains flavonoids (flavanones, flavones and flavonols), anthocyanins and coumarins [107] A natural citrus extract was evaluated as an antioxidant, and the activity was compared with α-tocopherol [108].It was concluded that the citrus extract-coated trays effectively inhibited lipid oxidation in cooked turkey meat slices, which was represented by significantly lower TBARS and hexanal values.
Green Vegetables: Extension of meat and meat products with green vegetables could reduce production costs and improve the nutritional qualities of the products.However, the suitability of vegetables in the production of meat products relates to their properties such as water binding, emulsification, yield and sensory properties.Addition of 2% carrot and 10% spinach improved the oxidative stability of poultry hamburgers [109].Lutein is a carotenoid that is present abundantly in dark green leafy vegetables such as spinach and kale, and is often termed as 'the eye-protective nutrient' as it is one of the most important dietary antioxidants for eye health [110].The experiments conducted by [111] showed antioxidative potential of various vegetable powders (10 g/145 g meat) in cooked turkey meat patties.Six (spinach < yellow pea < onion < red pepper < green pea < tomato) of 11 (beetroot, broccoli, carrot, celery, green pea, onion, red pepper, spinach, swede, tomato, and yellow pea) vegetable powders significantly (P < 0.05) improved oxidative stability of patties by 20% to 30%.

Oil Seeds
The by-products of different oilseeds are rich sources of phenolic Volume 2018; Issue 03 Food Nutr J, an open access journal ISSN: 2575-7091 compounds which can improve the nutritional value of the product.Some of them are listed as under: Canola extract: The antioxidative properties of canola extracts (500 and 1000 ppm) were more active than BHA, BHT and TBHQ [112].

Camelina meal:
The camelina meal also contains flavonols (quercetin glycosides), hydroxycinnamic acid derivatives (sinapine, and sinapic acids) and tocopherols.It exhibits more potential in inhibiting the oxidation of proteins than rapeseed phenolics.
Olive leaf extract: Olive leaf extract is a phenolic compound derived from olive leaves and is known to have antioxidative, antimicrobial, antiviral and anti-inflammatory properties and to protect low-density lipoprotein from oxidation, to have the capacity to inhibit lipid oxidation.

Miscellaneous
Almond skins: Naturally occurring antioxidants in almond skins include phenolic acids and flavonoids.Application of electron beam irradiated almond skin powder (0.5% w/w) significantly lowered lipid oxidation in raw minced top round beef [120] and potentially acted as a natural and inexpensive antioxidant in meat and meat products [121].

Edible mushroom:
[122] evaluated the antioxidant activity of hydrophilic extract prepared from edible mushroom (Flammulina velutipes) and the stabilizing effect on fresh color of bigeye tuna (Thunnus obesus) meat.The addition of 5 mL extract to 100 g minced bigeye tuna meat was more effective with regard to prevention of lipid oxidation.

Hydrolyzed potato protein:
The antioxidant effect of hydrolyzed potato protein (HPP) (0% and 2.5%) was investigated in frankfurters formulated at 2 fat levels (15% and 30%), and stored for 7 days [123].Meat emulsions with added HPP had lower redness and yellowness values.The addition of HPP (2.5%) significantly (P < 0.05) decreased cooking losses and fracture force, and had a significant (P < 0.05) inhibitory effect on lipid oxidation in cooked frankfurters.
Honey: Honey alters the water activity, thereby indirectly affecting oxidation rate.Moreover, it facilitates the Maillard reaction during the cooking process and thus the development of an antioxidant effect.Honey (15% w/w) was reported to retard lipid oxidation in cooked beef patties [124], turkey meat [125], chicken [126] and ground beef [127].
Rice hull extract: Rice hull is an attractive protective source due to its easily extractable antioxidant compounds.Furthermore, radiations (FIR) of rice hull liberate and activate covalently bound phenolic compounds that have antioxidant activities.
Soy protein hydrolysates: These are very frequently utilized in meat products as functional ingredients.Soy protein hydrolysates demonstrated inhibition of TBARS formation in an iron-catalyzed liposomal system [128].
Dry soya sprouts: These are rich in phenolics and flavonoids as well as have little amount of vitamin C and play an important role in preventing and treating chronic diseases such as heart ailments, osteoporosis, cancer, kidney ailments and menopausal syndromes [129].DPPH radical scavenging activity was comparable to BHA and could be used as a cheap natural antioxidant source for meat and meat products.
Potato peel extract: Potato Peel Extract (PPE) has a high phenolic content (catechin, chlorogenic acid).The effective utilization of potato peel, as an antioxidant in radiation processed lamb meat was investigated by [130].The antioxidant activity of PPE was found to be comparable to Butylated Hydroxytoluene (BHT).

Endogenous Antioxidants
Vitamin E (α-tocopherol): α-tocopherol has the ability to neutralize free radicals by reacting with peroxyl radicals to stop chain propagation and with alkoxyl radicals to inhibit the decomposition of the hydroperoxides and decrease the formation of aldehydes in cellular and subcellular membranes and protects oxymyoglobin oxidation.Postmortem addition of vitamin E was less effective.Thus, dietary vitamin E supplementation would be a safer and more effective method for retarding pigment and lipid oxidation in meat.
Ascorbic acid: Ascorbic Acid (AA) is a chelating agent that binds metal ions, scavenges free radicals and acts as a reducing agent.At high levels (> 1000 mg/kg), AA inhibits oxidation, however, at low levels (< 100 mg/kg) act as pro-oxidant and lead to Warmed Over Flavor (WOF) development [131].The solubility of ascorbate affects its ability to prevent discoloration [132].AA work synergistically with phosphates, sesamol and tocopherol to inhibit lipid oxidation [133].Whey: Whey is a cheap by-product of the cheese industry.Whey and whey ultra-filtration permeate have been used as a natural antioxidant in foods.Whey Protein Concentrate (WPC) showed a higher efficacy as antioxidant in cooked pork patties [134].

Animal Sources
Whey protein isolates at 2% and their hydrolytic products not only reduced the cooking loss but also suppressed lipid oxidation in cooked pork patties during refrigerated storage [128].
Casein peptides: Addition of casein peptides (20 mg/mL), obtained by the proteolytic enzymes alcalase and Flavourzyme [135] effectively inhibit lipid oxidation in ground beef homogenates and Mechanically Deboned Poultry Meat (MDM).The phosphorylated Caseinophosphopeptides (CPP) has the ability to scavenge free peroxyl radicals as well as to chelate transition metals such as iron, copper, and zinc [136].Incorporation of casein calcium peptides (2%) inhibited about 70% of lipid oxidation and prevents formation of an off-flavour in meat products [137].
Carnosine: Carnosine is a naturally occurring skeletal muscle dipeptide, which consists of alanine and histidine which act as both a buffering agent and as an antioxidant.The antioxidant activity is due to its ability to act as a chelator, free radical scavenger and hydrogen donor [138,139].Concluded that the combination of carnosine (50mM) with ascorbic acid (500 ppm) provided the best antioxidant protection for meat (beef steaks) during refrigerated storage.
Bone protein hydrolysates: These can be prepared by limited alcalase hydrolysis.It possessed significant antioxidant activity, which increased with the increasing hydrolysates concentration.Bone protein hydrolysates at 2% application level are able to not only stabilize meat colour but also suppress lipid oxidation in pork patties during storage and better sensory quality.

Conclusions
Most suitable antioxidant should be selected based on the character of food and the targets which should be attained.Synthetic antioxidants such as BHA, BHT and gallates were introduced in the 1940s.In recent years the meat industry is demanding antioxidants from natural sources to replace synthetic antioxidants because of the negative health consequences of some synthetic antioxidants and adverse toxicological reports on many synthetic compounds.Thus most of the recent investigations have been targeted towards identification of novel antioxidants from natural sources.Natural antioxidants have great impact on the safety and acceptability of the food system and will continue to do so.Not only do they keep the food stable against oxidation but can also be effective in controlling microbial growth.Therefore, the influence of these ingredients on meat quality parameters merits investigation as the use of natural antioxidants may afford the meat industry an opportunity to develop novel meat products with enhanced nutritional and health benefits, improved shelf-life and quality.However, further researches are needed to examine how different times and levels of supplementation, and how interactions with other natural antioxidants and food additives will affect the results.
graded the antioxidant activity of the various materials in the following order fresh garlic<garlic powder<BHA<garlic oil in raw chicken sausages during cold storage (3 °C).Garlic juice reduces the TBARS, peroxide value, residual nitrite in emulsified sausage during cold storage [60] and in fresh pork during cold storage [61].Volume 2018; Issue 03 Food Nutr J, an open access journal ISSN: 2575-7091 Milk proteins: Milk and milk components have been frequently Volume 2018; Issue 03 Food Nutr J, an open access journal ISSN: 2575-7091used in the enhancement of nutritional and technological properties of a wide variety of foods.A feasible application of peptides or hydrolysates as antioxidants is being explored especially in muscle foods.

. No Natural source Extraction methods Active ingredients (analyzed) Reference
along with their active principles.The further Volume 2018; Issue 03 Food Nutr J, an open access journal ISSN: 2575-7091 details about the use of different natural preservatives in meat and meat products are discussed below under different category.

Table 1 :
Active ingredients in natural antioxidants for meat and meat products.