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Copy of Copy of edible


mina fadat

on 8 June 2012

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Transcript of Copy of Copy of edible

a thin layer of material which can be consumed and provides a barrier to moisture, oxygen Edible coating Ad antages Ad antages Reduction of environmental pollution 1 prevent the contamination from microorganisms 2 Improve the mechanical handling property 3 4 moisture barrier on the surface of produce for helping alleviate the problem of moisture loss 5 Individual packaging of small portions 6 Create a controlled or modified atmosphere 7 To restrict the exchange of volatile compounds uality limited moisture-barrier properties Hydrophilic nature of most edible coating materials Development of undesirable sensory properties Off-flavors Anaerobic respiration Their permeability and mechanical properties are generally poorer than synthetic films Not equally efective on all produce 4 Edible
coating Hydrocolloides lipides Composites Wax Shellac resins Triglycerids Emulsion Suspension Dispersion Sucssesive layer Polysaccarides Proteins Pectin Seaweed extracts Chitosan Gums Aloe vera. Starch Cellulus The structural material of plant cell wall Repeating D-glucose units linked through ß-1, 4 glycosidic bonds cellulose derivatives 1 2 3 4 Hydroxypropyl cellulose (E463; HPC) Hydroxypropyl methylcellulose
(E464; HPMC) Carboxymethyl cellulose (CMC) Methyl cellulose (MC) Moderate strength Flexible Transparent Flavourless Colourless Tasteless Moderate barriers to oxygen Poor water vapour barriers Major carbohydrate reserve in
plant tubers and seed endosperm Starch derivatives Dextrins Pullulan used as film-formers and edible adhesives better water vapor resistance Odorless tasteless colorless low permeability to oxygen
at low RH low cost renew ability good mechanical properties Antifungal activity polysaccharides composed of sugars other than glucose Body Body Body exudate gums extractive gums microbial fermentation gums gum Arabic mesquite gum come from endosperm of
some legume seeds or extracted from the wood guar gum as a water binder, stabilizer and viscosity builder least viscous of the hydrocolloid gums readily dispersed in water acacia gum gum karaya uniform coatings with good cling and improved adhesion in wet batters A heterogeneous grouping of acidic structural polysaccharides prepared from citrus peel and apple pomace Agar Alginate a complex mixture of several polysaccharides that extracted from
the cell walls of various red seaweeds (Rhodophyceae) Carrageenans the major structural polysaccharides
of brown seaweed known as Phaeophyceae producing uniform transparent watersoluble films impervious to oils and fats high water vapor permeability improve the adhesion of batter to the surface of fruits and vegetables good oxygen barriers the gelling capacity in presence of Calcium a hydrophilic colloid consisting of a mixture of agarose and agaropectin a linear polymer of 2-amino-2-deoxy-β-D-glucan, is a deacetylated form of chitin made from crustacean shells the second most abundant natural and non-toxic polymer in nature after cellulose antifungal and antibacterial properties cohesive compact the film surface has a smooth contour without pores or cracks less flexible be good oxygen barriers at low relative humidities whey protein corn zein gelatin casein wheat gluten soy protein mungbean protein peanut protein oxygen barrier, carbon dioxide barrier and mechanical properties than polysaccharide films poor water vapor barrier property by the thermal denaturation of collagen, isolated from animal skin,bones and fish skins The properties and film forming ability of gelatins are directly related to the molecular weight, i.e., the higher the average molecular weight, the better the quality of the film transparent flexible colourless flavourless films poor moisture barrier good aroma barrier low oxygen permeability very brittle formed from 20-30% gelatin,10-30% plasticizer
(glycerin or sorbitol) and 40-70%water Zein is the most important protein in corn relatively hydrophobic thermoplastic material brittle biodegradable films good water vapor barriers compared to other edible films water-insoluble proteins of wheat flour which is composed of a mixture of polypeptide molecules Cohesiveness and elasticity of gluten give integrity tough, glossy, and hydrophobic grease-proof coatings and their resistance to microbial about 80% of the total milk proteins transparent,flavorless, and flexible transparent, flavorless, and flexible films excellent oxygenbarrier property in low and intermediate RH not good moisture barriers consisting of a blend of polysaccharides,protein, and/or lipids improve the permeability or mechanical properties
as dictated by the need of a specific application lipid generally forms an additional layer over the polysaccharide or protein layer lipid dispersed and entrapped in the matrix of protein or polysaccharide block transport of moisture due to their relative low polarity thicker and more brittle films Lipid-based films are often supported on a polymer structure matrix, usually a polysaccharide, to provide mechanical strength esters of long-chain monohydric alcohols and fatty acids Paraffin Carnauba Beewax Candelilla Mineral oil barrier gas and moisture improve the surface appearance providing a humidity barrier commercially applied as protective coatings for fresh whole fruits and vegetables since the 1930s reducing surface abrasion during fruit handling least permeable to gases among the available coating film-formers can easily undergo anaerobic respiration and flavor changes Some climatic fruit do not tolerate resin coatings are unstable when subjected to temperature changes secretion by the insect Laccifer lacca and is composed of a complex mixture of aliphatic alicyclic hydroxyl acid polymers present a greasy surface and undesirable organoleptic properties
such as waxy taste and lipid rancidity support aerobic respiration, resulting in high levels of
internal ethanol, acetaldehyde, and internal CO2 accumulation of off-flavors in the fruit good compatibility with other coating-forming agents high water vapor and gas-barrier properties poor aging increasing tortuosity photodegradation and fluctuations in ambient temperature
and humidity alter agar crystallinity & fungal cell walls Good oxygen barrier Transparent or translucent methods for films and coatings formation Solvent casting Extrusion Dipping Spraying used when the coating-forming solution is not very viscous Addition of regents Glycerol Decrese the ability of the film to attract water Polyethylene glycol Oligosaccharides ( sucrose) Sorbitol Water Polyols ( Propylene glycol ) Polysaccharides (or proteins) based edible Increase film permeability to gases ( or aroma compounds) Decrease the tensile strength Plasticizers of low molecular weight (non volatile) Plasticizers Antimicrobial agents Benzoic acid Propionic acid Sodium benzoate Sorbic acid Potassium sorbate Chitosan lysozyme Nisin lacticin pediocin antimicrobial enzymes chemical preservatives biopreservatives Natural compounds Rosemary garlic essential oils oregano lemon grass cinnamon oil chitinase glucose oxidase lactoperoxidase (LPS) Antioxidant agents phenolic compounds vitamins E Vitamin C Essential oils protecting foods against
oxidative rancidity,degradation,and discoloration Other functional agents Element Ca Zn Vitamins Flavour pigments be used as a host for carring basic nutrients and/or nutraceuticals
that are lacking or are present in
only low quantity in fruits and vegetables Introduction and solute movement for the food wax was the first edible coating 12th & 13th China 1930s Hot- melt paraffin 1982

lowings & cutts

mixture of sucrose fatty acid esters (SFAE)
+ sodium carboxymethyl cellu-lose, and mono- and di-glycerides

TAL Pro-long
Semperfresh 1 Flover coating materials 2 4 History 2 Methyl cellulose (MC) Pullulan Clear, odorless, tasteless, good oxygen barrier An extracellular microbial polysaccharide Researches Le Tien et.al (2001) Caseibate ; whey protein Oxygen barreir Methylcellulose Maftoonazad and Ramaswamy (2005) Oxygen / carbon dioxide / water barrier Pullulan Diab et.al (2001) Oxygen /carbon dioxide/water barrier Rojas-Argudo et.al (2005) Shellac and beewax Ruducing moisture Perez-Gago et.al (2003) HPMC/Lipid/ beeswax or shellac Reduce texture loss and internal breakdown Wheat gluten /beeswax based bilayer coating Retained firmness and reduce weight loss Tanada-Palmu and Grosso (2005) Valverde et.al (2005) Aloe vera.
control respiratory rate,
delay oxidative browning
and reduce microorganism
Prevent loss of mositure / firmness Park et al. (1994) Zein Delay color change
Reduce mositure / firmness loss
Reduce oxygen and carbon dioxide transmssion Retaining texture
Maintained higher POD activity
and lower activities of cell wall hydrolases
such as PE, PG, and cellulase Ran Zhou et al. (2011) Shellac Carboxymethyl cellulose Lower weight loss Delayed ascorbic acid loss Lower reduction in pH/soluble solids and titratable acidity Togrul and Nurhan (2004) Starch + Glycerol Suzana mali and Maria victoia (2003) Maria A. Garcia et al. (1998) Decreased WVP
Decresed weight losses
Retained fruit firmness for longer periods Lluís Palou et al. (2009) HPMC + lipid Lluís Palou et. al (2009) Reduced incidence and severity of both green (GM) and blue (BM) molds Jiankang cao et al. (2009) Chitosan Inhibited respiration rate, loss of firmness and color change Inhibited disease progress with Colletotrichum gloeosporioides Retarding moisture loss
Reducing hardening basal part
slowing down the purple colour development carboxymethyl-cellulose Maria V. Tzoumaki et al. (2009) Alginate + calcium Hershko and Nussinovitch (1998) Sealing -in volatile flavors.
Reduce shrikage, oxidative rancidity,
Improved appearance and color, Reducing weight loss Chitosan + Calcium Pilar Herna´ndez-Mun˜oz et al. (2006 and 2008) Reduced respiration activity Delayed changes in weight loss, firmness and external colour Reduced fruit weight loss Delaying fungal decay The concept of edible films and coatings represents
a stimulating route for creating new packaging
materials. This is because edible films and coatings
are available with a wide range of properties that
can help to alleviate many problems encountered
with friuts and vegtables by
retarding dehydration, suppressing respiration,
improving texture quality, helping retain volatile flavor compounds
and reducing microbial contamination Conclusions Wax + CMC To˘ grul and Arslan (2004) Water barrier Direct application of antimicrobial agents onto fruits and vegetables surfaces by dipping has proven to be less effective as there is loss of activity because of leaching onto the surface, enzymatic activity, and reaction with other components 3 non uniform and/ or sticky surface Brushing 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 nonuniform and sticky surface 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 33 34 35 36 36 37 38 39 40 40 41 42 43 44 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 Safizadeh and Rahemi ( 1992 ) Paraffin + bee wax Reducing fruit weight loss Retained firmness and fresh apperance Rostaii and Rahemi ( 2012 ) Pectin and olive oil reducing precentage of mold rot fungicidal Increased in pulp/peel ratio
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