*1.4.2 Nature of the packaging material*

For an ideal packaging, the packaging material should be; (i) non-reactive to the food (ii) non corrosive (iii) impermeable (iv) sealable (v). Packaging materials such as glass and metal provide total barrier to external factors therefore migration occurs only form the internal contact surfaces. Semipermeable packaging material such as plastics offers limited resistance to permeation and migration therefore used only on properly selected food materials. Porous materials such as paper and paper boards facilitate rapid migration [25]. Interaction rate depends on factors such as (i) molecular weight (ii) density (additive present (iii) temperature (iv) crystallability of the packaging material use. With the increase in use of polymer based packaging materials, over 42% of a the polymers produced are used as packaging materials, and about half are used for food packaging applications [26, 27]. They are usually preferred in food packaging due to their flexibility, low density, strength, ease to mold, cost, controlled hydrophobicity and moldability into different sizes and shape. Several researches shows that there is increase in interaction of food if package in polymer based packaging which can induce undesirable quality changes in packed food. For

instance, degree of browning and ascorbic acid degradation of orange and grapefruit juice was found to be high when packed in polyethylene-laminated cartons than in glass [28]. Bott et al. [29] reported that the rate of interaction of LDPE and polystearine decrease by 10 fold with the increase in the molecular weight of the packaging material. Migration rate in polypropylene increases with decrease in the crystallability [30] rate of migration in polyprpyene packaging increase with decrease in crystallability of the polymer.

Interaction of packaging material with the food and the environment plays a major role on quality of the product as well as integrity of the package. These effects have impact on market value, goodwill of the manufacturer, sensory attributes of products and health effect of consumers. Moreover, strict legislations are set for 'zero tolerance' of carcinogenic migrants, and also the compounds that migrate into food are considered as indirect food additive by FDA. Hence, knowledge on factors affecting interaction phenomena and its effect are of high importance. The ability of the packaging to absorbed or release light should also be considered in selecting package for oily/fatty foods, example, polyolefins are not advisable for the packaging of lipophilic food [30]. Other than the polymer itself, the nature of additives like colorants, plasticizers, stabilizers, fillers, blowing agents, antioxidants, antimicrobials, slip compounds and printing ink also migrates into the food material, and their characteristics impact the rate of migration [31] which may be toxic if consumed with food. Example, residual ethylene oxide on metal cans is highly toxic [32], concentration of tin lacquer at about 500mgkg−1 can cause gastrointestinal ailments [33] and usually attain acute threshold at about >730 mgkg−1. Lacquers are usually added to reduce interaction of food and packaging as well as with external environment by reducing oxygen scavenging [34] lead coating on beverage containers can cause damage to central nervous system and has negative growth impact, it could also result to mental retardation [35] chemical components of paper packaging such as dioxins, nitrosamines, chlorophenols, chloroanisoles and benzophenone are toxic if found in food [35–37]. 0.06–1.0% of acetaldehyde was detected in different beverages packaged on PET plastic containers by Lau & Wong [38], acetaldehyde usually impact odors on food especially in cola-type beverages [39] therefore its presence in food is of great significance.

Health related risk assessment from chemical and materials to be used in producing food packaging should be considered and thoroughly studied before used, to prevent contact and potential migration of these chemical/materials into the food which may be carcinogens or caused other ailments. Trace of metal, additives, inks and plastics from the packaging or from environment due to failure of packaging should be eliminated to prevent the food and the consumer health. Hazard related to presence of metals contaminants in foods raised serious health concerns. Acute and chronic symptoms such as dizziness, nausea, diarrhea, loss of appetite, disorders, vomiting and reduced contraception rate has been associated with metal toxicity, and these symptom may results to a serious cardiovascular diseases, suppressed growth, impaired fertility, immune disorders/failure and or neurological ailments which may lead to death [39].

#### *1.4.3 Environmental and storage factors*

Environmental factors such as (i) temperature (ii) relative humidity (iii) storage time (iv) moisture content (v) oxygen and other gaseous content. Change in environmental temperature affect the stability of the packaging-food interaction

## *Food Preservation Packaging DOI: http://dx.doi.org/10.5772/intechopen.110043*

rate by increasing the mobility of interacting material, free volume and the swelling capacity of the packaging film. Storage time also increases the rate of food-packaging interaction with heat processed cans suffering more migration effect than non-heat processed materials [40]. Different packaging material offers different migration rate in relation to change in the environmental relative humidity. Permeation through EVOH packs increase with increase in environmental humidity while there is decrease in permeation in PET and nylon with increase in relative humidity of storage environment.
