Optimizing packaging 445 The VTT Concept uses mathematical modelling to determine the minimum package requirements for the foodstuff. The modelling of the shelf-life of foodstuffs is performed in the following steps: (1) selecting factors and responses,(ii) selecting the experimental design method (screening or more extensive method),(iii) carrying out tests, (iv) analysing results,(v) making shelf-life predictions and(vi) determining the minimum package requirements The factors that might be relevant and might affect the quality deterioration of the foodstuff are chosen, for example, oxygen transmission rate of a packaging material, carbon dioxide concentration of a package, ge volume and storage conditions(temperature, illumination, etc. ) The parameters In shelf-life testing of food can include sensory and analyses and microbiological determinations. The minimum package requirements can also be based both on the information of the shelf-life tests and on the literature data 21.3. 2 Determining different package and storage combinations After the required packaging parameters for a foodstuff at certain storage conditions have been determined, it is possible to select the different alternatives of packages and packaging materials, packaging methods and package conditions all of which give equally acceptable food quality at the end of the required shelf-life of the product (e.g. vacuum or gas-flushed package wit specified packaging material and gas concentrations) 21.3.3 Scoring the selected alternative package type The selected, alternative package types giving the same minimum required shelf-life, are first scored by rating different characteristics of each package type. As an example, the following package attributes can be used in a Precision Packaging Concept mechanical strength of a package suitability with respect to packaging standards ratio of package weight to product weight volume of package waste ibility of incineration life cycle assessment of packages marketing properties of a package consumer convenience consumer attitude cost of packaging material indirect packaging cos All these characteristics are scored on a scale from I to 5, with I corresponding to poor and 5 to excellent quality. Fractional numbers are also allowed. The scoring is performed in co-operation with experts representing wholesalers, food manufacturers, packaging material manufacturers and independent specialists of ackaging technology and plastics industry
The VTT Concept uses mathematical modelling to determine the minimum package requirements for the foodstuff. The modelling of the shelf-life of foodstuffs is performed in the following steps: (i) selecting factors and responses, (ii) selecting the experimental design method (screening or more extensive method), (iii) carrying out tests, (iv) analysing results, (v) making shelf-life predictions and (vi) determining the minimum package requirements. The factors that might be relevant and might affect the quality deterioration of the foodstuff are chosen, for example, oxygen transmission rate of a packaging material, carbon dioxide concentration of a package, package volume and storage conditions (temperature, illumination, etc.). The quality parameters in shelf-life testing of food can include sensory and chemical analyses and microbiological determinations. The minimum package requirements can also be based both on the information of the shelf-life tests and on the literature data. 21.3.2 Determining different package and storage combinations After the required packaging parameters for a foodstuff at certain storage conditions have been determined, it is possible to select the different alternatives of packages and packaging materials, packaging methods and package conditions all of which give equally acceptable food quality at the end of the required shelf-life of the product (e.g. vacuum or gas-flushed package with specified packaging material and gas concentrations). 21.3.3 Scoring the selected alternative package types The selected, alternative package types giving the same minimum required shelf-life, are first scored by rating different characteristics of each package type. As an example, the following package attributes can be used in a Precision Packaging Concept: • mechanical strength of a package • suitability with respect to packaging standards • ratio of package weight to product weight • volume of package waste • possibility of incineration • life cycle assessment of packages • marketing properties of a package • consumer convenience • consumer attitudes • cost of packaging material • indirect packaging costs. All these characteristics are scored on a scale from 1 to 5, with 1 corresponding to poor and 5 to excellent quality. Fractional numbers are also allowed. The scoring is performed in co-operation with experts representing wholesalers, food manufacturers, packaging material manufacturers and independent specialists of packaging technology and plastics industry. Optimizing packaging 445
446 Novel food packaging techniques Mechanical strength of a package This is determined using a simulated transportation test. For example in the VTT ransportation test, a whole pallet positioned on a vibration table is subjected to a simulated road transportation of about 1000 km. As an example, during this 45- minute test run. the table is vibrated at a constant acceleration of 0.5 g. with the frequency of the table sweeping between 5 and 55 Hz. Since each package type resonates at its own specific frequency, every package tested is exposed to mor or less high accelerations during the test procedure. In general, the packages in the top layer of a pallet are exposed to the highest accelerations, which can be even more than 6 g. After the test, all the possible flaws, such as flexes, fractures, open seals and product disorientation originating from the transportation tests are recorded, and the test packages are scored as follows I point: if even one tested package in the pallet is leaking, the whole sample group is rejected Suitability with respect to packaging standard. This is evaluated by examining the volume occupied by the primary packages tested in a secondary package, which had the dimensions of the pallet area Scores between I and 5 are given on the following basis I point: relatively large empty space left in the secondary package 5 points: primary packages tight together, no empty space in the secondary tio of package weight to product weight score for this ratio(= Sm)is calculated using eqn I Sm=0.444.(1-m/m:100+5 where mp= weight of the empty package and m= weight of the packaged food Equation I was formulated on the following basis I point corresponds to an empty package weighing 10% of the weight of the packaged product, and 5 points correspond to an empty package weighing 1% of the weight of the packaged product ge waste This is scored from 1 to 5 on the following basis I point: a rigid package, e.g. tray, which cannot be scrunched and which would require a large space in a household waste basket 5 points: a package that is made of a thin flexible material, which can easily be put in a household waste basket without the need for stuffing or crunching
Mechanical strength of a package This is determined using a simulated transportation test. For example in the VTT transportation test, a whole pallet positioned on a vibration table is subjected to a simulated road transportation of about 1000 km. As an example, during this 45- minute test run, the table is vibrated at a constant acceleration of 0.5 g, with the frequency of the table sweeping between 5 and 55 Hz. Since each package type resonates at its own specific frequency, every package tested is exposed to more or less high accelerations during the test procedure. In general, the packages in the top layer of a pallet are exposed to the highest accelerations, which can be even more than 6 g. After the test, all the possible flaws, such as flexes, fractures, open seals and product disorientation originating from the transportation tests are recorded, and the test packages are scored as follows: • 1 point: if even one tested package in the pallet is leaking, the whole sample group is rejected. • 3 points: there are some minor dents or flexes. • 5 points: no package is affected by the vibration test. Suitability with respect to packaging standards This is evaluated by examining the volume occupied by the primary packages tested in a secondary package, which had the dimensions of the pallet area. Scores between 1 and 5 are given on the following basis: • 1 point: relatively large empty space left in the secondary package. • 5 points: primary packages tight together, no empty space in the secondary package. Ratio of package weight to product weight The score for this ratio ( Sm) is calculated using eqn 1 Sm 0:444 1 ÿ mp=mf 100 5 1 where mp weight of the empty package and mf weight of the packaged food. Equation 1 was formulated on the following basis: • 1 point corresponds to an empty package weighing 10% of the weight of the packaged product, and • 5 points correspond to an empty package weighing 1% of the weight of the packaged product. Volume of package waste This is scored from 1 to 5 on the following basis: • 1 point: a rigid package, e.g. tray, which cannot be scrunched and which would require a large space in a household waste basket. • 5 points: a package that is made of a thin flexible material, which can easily be put in a household waste basket without the need for stuffing or scrunching. 446 Novel food packaging techniques