"New Tendencies in Preservation of Fruits and Vegetables by Edible coatings." Laboratoire Maîtrise des Technologies Agro-Industrielles ( LMTAI ) Pôle sciences et Technologie - Université La Rochelle Presented by Prof. Dr. Ibtisam Kamal
Preservation of Fresh Fruits and Vegetables New Research concerning (edible) coating of cut fresh products
Introduction: Packaging: Is a process to maintain the quality of food products for storage, transportation and enduse. It prevents quality deterioration and facitilate distribution and marketing.
Materials used for food packaging: Petroleum derived plastics Metals Glass Paper board
Plastics as packaging materials: Advantages: Provide excellent protection. Cheap to manufacture. Shortcomings: Cause a major environmental problem. Manufactured from non-renewable sources.
Bio-based polymer packagings: Biodegradability Edibility Produced from renewable resources Can be recycled
Packaging films for food products:
Bio-polymer Edible Coatings Edible films are thin layers of biopolymer material that are usually used for encapsulating food and pharmaceutical products. They are formed on the surface as protective or decorating foodstuffs coatings, or placed between food components to separate them. The environmental friendly films and coatings are bio-compatible, non-toxic and acceptable to human consumption. Applications: Already, edible films have been applied to meat, poultry, fruits, vegetables, grains, and confectionery products, heterogeneous foods, any of which can be fresh, frozen, cured or processed.
The objectives achieved from using edible films and coatings are : Maintain the quality and extend shelf-life of food products. Decrease fruit peel permeability. Reduce the need of packaging materials and the amount of disposable nonbiodegradable packaging materials.
Edible coatings intervene by: Depressing food respiration rate. Serving as barriers for water vapor, oxygen, etc.
Their effect is reinforced by: Reducing water vapor, oxygen, lipids and flavors migration in multicomponent food products between food and surrounding atmosphere. Serving as carriers for a wide range of food additives, including thermolabile compounds like vitamins, aroma and flavors, antioxidants and colorants, fortified nutrients, and/or spices providing an efficient method to preserve their characteristics during food processing. Reducing oil uptake in fried products.
What are Polymers? Polymers are substances containing a large number of structural units joined by the same type of linkage. These substances often form into a chain-like structure. Polymers in the natural world have been around since the beginning of time. Starch, cellulose, and rubber all possess polymeric properties. Man-made polymers have been studied since 1832. Today, the polymer industry has grown to be larger than the aluminum, copper and steel industries combined. Grafted copolymer Block copolymer Random copolymer Branched polymer
Polymers Bio based polymers Mineral oil derived polymers Polymers directly extracted/ removed from natural materials. ex.: polysaccharides, proteins. Polymers produced by microorganisms or genetically transformed bacteria.. Ex. : polyhydroxybutyrate Polymers produced by classical chemical Synthesis from renewable bio-derived monomers. ex. : polylactate
Bio-polymer Polysaccharides Chemical Structure Examples Pectins, MC, EC, HPMC, Starch, chitosan, xanthanes Sucrose esters, pollulan, alginates. Proteins Wheat protein, soy protein, milk protein, Zien, glutenn, and Gelatein, Lipids Palmitic acid Srearic acid Lauric acid Bee wax Fats and oils
Resinous biopolymers:
Edible coatings for ready-to-eat products:
How to combine Edible coating to DIC treatment? 1. Applying DIC: 1. for decontaminating fresh cut fruits and vegetables (Superficial effect?) 2. The ffect concerning Enzymatic inhibition 2. Applying the solution of edible coat under vacuum within DIC process 3. Drying the edible coating (conventional drying)
1 2 3 C A B Schematic diagram of the DIC unit (1) : Reaction chamber. (2) : Pressure-Drop valve. (3) : Vacuum tank. (A) : Steam generator. (B) : condenser. (C) : Vacuum pump. The operation principle of the process is composed of four sequential stages : 1. Preliminary Vacuum stage: For getting the greatest contact between steam and product surface. 2. Injection of steam: Establishing during tens seconds steam pressure for controlling the temperature of product (T<200 C, P< 20 bar s). 3. Pressure-Drop: Establishing an abrupt pressure drop (>>5 bars.sec-1) towards vacuum, which implies auto-vaporization, cooling and a perfectly controlled swelling of the product. 4. Returning to atmospheric pressure.
Profile of a thermal DIC treatment c b a e d 5 g f 4 100 80 3 60 2 40 1 104 98 91 85 78 72 65 59 46 52 40 33 26 20 13 0 7 20 1 Heating stage Température ( C) 120 0 Temps (s) Sample Temperature of the Pressure within treatment Chamber Pressure in the empty reservoir Pression absolue (bar) 140 Cooling stage
FLOW CHART FOR MANUFACTURING, PROCESSING AND EVALUATION OF EDIBLE COATINGS. Raw material Industrial waste DIC Treatment Formulation Dissolving in solvent Mechanical shear and/or heat Adding plasticizer and additives Sensorial and Biochemical Characterization DIC Edible Polymer Solution Application of the edible coating on foods Edible coated dried, cooked or fresh product Barrier Properties vis-à-vis of O2, CO2 and water Vapour permeability Microbial analysis Sensory Analysis, Color Performance evaluation Casting Edible free standing Rheological characteristics Physical & chemical Characterization Solubility Barrier Microscopy Color & transparancy Mechanical & thermal behavior
Objectives of the work: DIC + Edible Coating = New Food Processing Technology 1. DIC may intervene in the preparation of biopolymers:(raw material: food-industrial waste, ) 2. DIC intervene for preserving fruits and vegetables (Microbiological and enzymatic effects). The developed coating materials adopted will be applied through the new combined technology to improve the eating quality and increase the shelf-life time of the processed foods.
The edible coating solutions The raw biopolymers The edible coating films
Factors influencing functional properties of edible films:. Polymer type, purity and concentration in solution.. Method of preparation:.effect of dissolving solvent..effect of ph..plasticizers or additives used..film drying temperature.. Intrinsic food properties (ph, water activity, and composition).. Extrinsic factors (i.e. temperature and relative humidity) in processing and storage conditions.
The main technical and economical advantages of this field of research are: 1. To minimize (valorize) food wastes. 2. To preserve shelf life time and convenience of fresh (cut) fruits and vegetable, this will reflect positively on conservation of energy needed for storage. 3. To control the storage and quality of foods; 4. To obtain lightly processed food, in addition to the controlled and precise sterilization, texturing and preservation of both fresh and dried foods. 5. To get relatively simple and cheap equipments for applying the coating materials. The combination of DIC- Edible coating process preserves time and energy needed
Samples stored at room temperature for seven days.
Potato fingers : Samples stored at for 165 days. Stored at 5 C Room temperature A: DIC-MC coated B: DIC -MC coated. C : Control samples. D:Control samples.