Saffron packaging

Introduction

The quality of food might be deteriorated biologically, chemically, and physically, when the product is distributed. Therefore, food packaging is needed to extend the shelf-life and maintain the quality and safety of the food products. The packaging mainly protects the food from environmental physical damage, humidity, oxygen, light, and, to some extent, temperature. Packaging can also protect foods against microbial contamination. Good package integrity is also required to protect food against loss of hermetic condition and microbial penetration. Although food products manufactured by retorting or aseptic processing do not require refrigeration shelf-stable packaging is needed as a barrier against the invasion of microorganisms. Marketing is another important function of food packaging, which provides traceability, indications of tampering, and portion control. Packaging is the main communication element for the product at the point-of-sale and allows the consumer to appreciate the position chosen by the brand. Therefore, all food packaging must communicate with the consumer. Not only must the contents be identified, but the packaging should contribute to sales and marketing efforts. Packaging design is one of the important tools in modern marketing and consumer acceptability of the product. The color of the package has a psychological effect on the behavior of buyers in different ways.

The information on the label of package regarding the internal and international standards and also about the saffron nutritional values have the greatest impact on the consumer acceptability. The brand labeled on saffron package is another important issue from the perspective of the consumers. Therefore, producers and suppliers of saffron should pay more attention to the features and information on the package design. The attributes of food and packaging materials have a direct influence on the quality of the packaged food. Most food products deteriorate in quality due to mass transfer phenomena, such as moisture absorption, oxygen invasion, flavor loss, undesirable odor absorption, and the migration of packaging components into the food. Therefore, in order to find a proper package, a number of considerations must be taken into account. First, the package must provide the optimum protective properties to keep the product in good condition for its anticipated shelf-life. Second, the package should have good shape and size and its graphics must attract the eyes of the purchaser. Although preservation, convenience, and other basic functions of packaging are certainly important, its disposal should also be considered an important aspect of packaging development.

For herbs and spices it is important to know how to store them effectively in order to reduce their deterioration during storage. Most herbs are marketed in dried form in order to avoid product deterioration over time. Several factors such as ease of opening, reseal features, pouring qualities, protection from light, transparency, tamper-proof construction, and physical characteristics of outside surface including appearance must be taken into account when choosing a suitable packaging material for herbs and spices.

Saffron packaging

After drying and sorting the stigmas, saffron is ready for packaging and release. The most important factors decreasing the quality of stigmas during storage are climatic influences that cause physical and chemical changes [ultraviolet (UV) light, moisture vapor, oxygen, and temperature changes]; contamination (by microorganisms, insects, or soils); and also saffron packaging materials. These factors should be considered and most of them should be avoided during packaging of saffron stigmas.

The primary purpose of stigmas packaging is to preserve the flavor and color and also to keep the product in good condition until it reaches consumers. In order to reduce oxidation reactions, it is important to avoid high-temperature storage, utilize packaging with low oxygen permeability and use modified atmosphere packaging. Most common packages used for these purposes are glassware, polyethylene bags, polyethylene jars, and aluminum-layered bags. In most cases saffron is placed inside cardboard, wood, or metal boxes to prevent the package from pressing and breaking during shipping.

Paper and paperboard

Paper and paperboard are felted sheets, usually composed of plant fibers or other fibrous materials which are used to make package. They are categorized by the weight or thickness of the product, with paper being lighter than paperboard. These are the least expensive packages for whole spices. Paper and paperboard packages are easy collected, reused, and recycled. The excellent stiffness and dead fold of papers and paperboards allow them to be used for bags, ensuring their creases are sharp and they stand erect on shelves. The tensile strength of paper and paperboard is high and their extensibility low, allowing for good constant tension to be applied when printing and laminating papers and during the manufacture of corrugated board. This high printability is ideal for displaying product information and nutritional value for marketing purposes.

One of the negative properties of paper and paperboard is that they have high permeability to flavor components and gases and absorb moisture vapor and water. Therefore, paper and paperboard are unsuitable for ground spices and saffron. To improve the gas or wet barrier properties and the strength of paper and paperboard, they can easily be combined with other materials such as oil, wax, polymers (plastics), and metals through coating or lamination. Wax coating on the outside of the packaging improves attractiveness and resistance to water; while polyethylene coating inside gives extra protection and seal ability to papers and paperboards. Paper and paperboard are mainly used as secondary packages for saffron packaging and thus are not directly in contact with the product inside the package. Therefore, there is no need to combine these papers with other materials or use coatings or lamination with plastics.

Aluminum foil

Metal can provide good protection against physical damage and provide a good barrier against water, oxygen, and gases. Among metals aluminum has a number of important characteristics such as its light weight, high yield strengths in its alloy form, and resistance to corrosion; additionally, it is easy to form and is a good conductor of heat and electricity. When exposed to air, aluminum forms a transparent oxide layer, which prevents further oxidation. As well as being resistant to corrosion, aluminum is nonabsorbent and thus an effective barrier against gases and liquid. Its resistance to gas transmission is essential to protect the delicate flavor of many spices. Aluminum does not generate toxic residues or react with most chemicals including the majority of foods. It is not transparent and is ideal for spices that need protection from light. Therefore, aluminum foils have great potential for packaging saffron. Aluminum can easily be recycled and used again for packaging, which is another important advantage of this metal. 

Glass

Glass is one of the oldest packaging materials and is made of silica (quartz), which is the principal component of sand. Glass surfaces may be treated with titanium, aluminum, or zirconium compounds to increase their strength and enable thinner and lighter containers. Using boron compounds (borax, boric oxide) give high heat-shock resistance to the glass. The majority of glass used for food containers can be easily reused and recycled. 

As a food packaging material, glass has both disadvantages and advantages. One of the advantages of glass is that it does not react with food to produce hazardous or undesirable compounds. Glass has also good barrier properties against gases and chemicals and can tolerate high temperatures. The transparency of glass is preferred by consumers because it provides visibility of the saffron inside. However, glass is prone to breakage upon physical impact and high pressure.

Another disadvantage is that translucent materials such as glass have little protection against photooxidation and the light energy can pass through the material and result in photochemical reactions, which lead to product discoloration. Amber glass is able to filter out UV light and is primarily used for UV-sensitive products.

Low-density polyethylene

Low-density polyethylene (LDPE) is one of the most widely used packaging plastics. It is translucent in appearance, heat sealable, chemically inert, odor free, soft, and flexible with good elongation before breakage and good puncture resistance. LDPE has a fair moisture barrier property but has relatively high gas permeability. It is also characterized by its fair machinability, good oil resistance, fair chemical resistance, good heat sealing characteristics, and low cost. Since LDPE softens at around 100_C, it is an economical polymer to be processed and is readily heat sealable.

Linear low-density polyethylene (LLDPE) is produced as either a homopolymer or copolymer having comonomer alkenes such as butane, hexane, and octane. It has similar properties to LDPE, although it is tougher with slightly better barrier properties. Due to the increased regularity of the structure and narrower molecular weight distribution, the mechanical properties of LLDPE are improved compared to LDPE at the same density. When compared with LDPE, LLDPE requires slightly more energy to be heat sealed and its operating range for sealing is narrower. Therefore, controlling the seal temperature on the packaging machine is more critical. LLDPE is also a little more transparent than LDPE. 

The moisture, crocin, picrocrocin, and microbial content decreased during storage of saffron in polyethylene bags for 1 year. The largest variations were observed until 8 months of storage and after that the variations were not significant. LDPE pouches could also be used for storage of saffron flowers. LDPE pouches maintained the physical and quality properties of saffron flowers especially when stored at 0_C. 

High-density polyethylene

High-density polyethylene (HDPE) is a translucent polymerized film that has higher crystallinity and provides a good barrier against gas and water compared to LDPE. It is stronger, thicker, less flexible, and more brittle than LDPE. It is waterproof and has excellent resistance to a wide range of chemical compounds. The melting temperature (Tm) of this film is around 135_C and thus it withstands boiling water. Therefore, HDPE is suitable as a film for boil-in-the-bag foods. However, it is prone to environmental stress cracking.

Modified atmosphere packaging

Modified atmosphere packaging (MAP) is a term that implies the addition or removal of gases from packages in order to manipulate the levels of gases such as oxygen, carbon dioxide, nitrogen, ethylene, etc. MAP is mainly used to extend the shelf-life of food products and to prevent any undesirable changes in foods. MAP dramatically extends the shelf-life of packaged food products, and in some cases MAP products do not require any further treatment or any special care during distribution.

The use of MAP for storage of Spanish saffron showed a marked decrease in its color loss during storage.  During storage of Iranian saffron under modified atmosphere, the rate of decrease in the content of microorganisms was higher. Therefore, in situations where chemical additives may be of concern, MAP can be used effectively for packaging saffron.

Nanosilver composite antimicrobial packaging

Nanotechnology has been touted as the next revolution in many industries, including food processing and packaging.

Addition of nanocomposites or nanoparticles (e.g., silver, titanium dioxide, silicon dioxide, nanoclay) into food packaging materials is done to ensure better protection of foods by increasing barrier properties, blocking UV light, improving mechanical and heat-resistance properties, and developing antimicrobial and antifungal surfaces.

Antimicrobial packaging is used to extend the shelf-life of food products through prevention of spoilage and pathogenic microorganism growth. Antimicrobial packaging systems are able to kill or inhibit microorganisms that cause food spoilage or foodborne illnesses. Sliver and porous materials complexes with silver such as zeolite used as antimicrobial particles besides polymeric films or surface coating. However, nanosilver particles have shown notable antimicrobial activity and have higher Ag1 ions release rate compare to that of bulk silver. Polyethylene_nanosilver composites packaging can prevent or limit the microbial putrefaction of saffron. However, since the release rate is mainly under the control of several factors such as moisture, there is a delay in the antibacterial effects of nanosilver due to the dry nature of saffron. Therefore, although packaging with polymer_nanosilver can maintain growth inhibition or killing of microorganisms in dry products, these effects are not similar to those recognized for liquid and semiliquid foods, like beverages. Among the microorganisms, Salmonella enteritidis and enterococci are more susceptible to silver, while fungi are less sensitive to the agent. Nanosilver particle film packaging could also increase the flavor and aroma of saffron during storage. 

Edible and biodegradable films

Synthetic polymer materials used in the packaging industries are nonbiodegradable and therefore lead to environmental pollution, posing serious ecological problems. Biopolymer films have received increased attention because of their biodegradability. Antimicrobial agents can also be added to these polymers for controlling the contamination of food packed inside. Edible and biodegradable natural

polymer films offer alternative packaging with lower environmental cost. Biodegradable films are generally made from biopolymers such as polysaccharides, proteins, and lipids. These materials have been widely considered as prospective replacers of synthetic polymers such as plastics. However, these biopolymers are not plastic, and it is not feasible to produce biopolymers using existing machinery in plastic packaging plants. These environmentally friendly films must meet a number of specific functional requirements such as moisture barrier, solute and/or gas barrier, color and appearance, mechanical and rheological features, and nontoxicity. Generally, biopolymeric materials provide high oxygen and flavor barrier properties but lower water barrier properties, mostly depending on moisture content and the amount of plasticizers. The use of biopolymers as a packaging material is limited due to their production costs, functionality, and compatibility with other polymers in current recycling streams. 

Films made from only one kind of natural polymer display good properties in some aspects, while poor in others. In order to improve the film properties simultaneously, two or more biopolymers can be combined. Functional properties of composite films depend on their composition and film-forming procedure. These blends can strongly improve the physical and chemical properties of films prepared by each polymer. Films prepared from binary polymeric blends have different structures, which influence their final properties. Fatty acids, lipids, and waxes are commonly used in polysaccharide and protein edible films to reduce their water-vapor permeability since these materials are hydrophobic and thus are good barriers against moisture migration. 

Conclusion

Barrier properties including permeability of gases, water vapor, aromas, and light are vital factors for maintaining the quality of saffron. Most common packages used for saffron are glassware, LDPE, HDPE, and aluminum-layered bags. Among these packages, LDPE is the most common while glass container does not react with saffron and has good barrier properties against gases. In order to increase the shelf-life of saffron, MAP could be used, which reduces the color loss during storage. To ensure better protection of saffron, nanosilver particles could be added to the package.

Polymer_nanosilver can inhibit growth of or kill microorganisms. The substitution of artificial chemical ingredients in packaging materials with natural ingredients is always attractive to consumers. Biopolymer films are a great alternative to synthetic polymer materials due to their biodegradability. Therefore, combinations of biopolymers with good barrier properties could be used for saffron packaging in the future.