Films|Flexibles|Bags
Films|Flexibles|Bags Longer Shelf Life in PLA Packaging Pepper and tomatoes stay longer fresh By Paolo Serafin Sales Manager NATIVIA Taghleef Industries San Giorgio di Nogaro, Italy Consumer awareness with regard to more sustainable packaging is also pushing the use of bioplastics in the fruit and vegetables market, but there’s more than just an environmental advantage. Taghleef Industries, manufacturer of BOPP and BOPLA films, in cooperation with EOSTA and Bio4Pack, commissioned a study on the shelf life of bell peppers and vine tomatoes packed in PLA vs PP to the Univeristy of Wageningen, which produced some very interesting results. PLA (polylactic acid) is emerging in the packaging industry as the most promising alternative to oil-based plastics, thanks to its performance, availability and versatility. It’s already in use in rigid packaging (injection molding), semirigid (thermoforming and blow molding) and flexibles (film). At Taghleef Industries Italy, PLA is extruded into sheet and sequentially oriented in machine and transversal direction, in a production process very similar to that of BoPET and BoPP. PLA film is heat sealable and used for packaging products on traditional horizontal and vertical form/fill sealing machines, as well as on twist wrap and overwrap machines. Recent developments have also seen the use of PLA films for windows on paper bags, adhesive tapes, paper lamination and labels. Eosta, the market leader in the organic fruit and vegetables market in Europe, have used PLA for many years for the thermoformed trays and overwrapping film in which they pack their products. Besides contributing to minimizing the environmental impact of their packaging, PLA gives Eosta the chance to differentiate themselves from the competition and offer a packaging solution which fits perfectly with their mission and target customers. Having noticed an improvement in the preservation of their products using PLA compared to the standard PP packaging, Eosta, Taghleef Industries and Bio4pack have decided to carry out a detailed analysis, and commissioned this task to Wageningen University, one of the most experienced in this field, choosing two of the most common products: bell peppers and vine tomatoes. The test: Samples of the peppers and tomatoes were taken from the same lot, making sure that the harvest date was the same for the whole batch. Peppers were packed using a horizontal FFS (Form Fill Seal) machine and macro-perforated transparent PLA and PP films. The same packaging films were used for the thermoformed trays containing the vine tomatoes. Packaging and storage were done under the same conditions for all samples, also simulating the conditions available in retail stores. Unpacked products were also included in the analysis for a complete comparison and reference. The monitored parameters were: VINE TOMATOES: • Firmness • Fruit rot • Dehydration of wood stem • Stem rotten • Colour BELL PEPPERS: • Firmness • Dehydration/wrinkling • Fruit rot • Stem rotten, and freshness 18 bioplastics MAGAZINE [06/11] Vol. 6
Films|Flexibles|Bags Results: TOMATOES: As depicted in Fig. 1, PLA packaging contributed to delaying by approx. two days the crown and stem dehydration index, which emerged as the first aging sign of this product in comparison with the product packed in PP. This ageing factor is rather important, being clearly visible to the consumer. The other parameters did not show relevant differences and they all crossed the ‘acceptable’ threshold several days after the crown and stem index was negative, confirming that stem dehydration is the limiting parameter in the shelf life of tomatoes. PEPPERS: With regard to bell peppers, a positive effect of PLA was noticed in the firmness of the fruit when compared with PP (Fig. 2), but an improvement can also be observed on the stem index, which shows a slower degradation, remaining within the acceptable limits for 1-2 days longer than product packed in PP (Fig. 3). The other parameters did not show noticeable differences. In the case of peppers, dehydration (shrivelling) emerges at the same time as the limiting quality parameter for both PP and PLA, well before the others and even earlier if the product is unpacked. Nevertheless, this means that, as the use-by date gets closer, peppers packed in PLA will show a better stem and firmness compared to those packed in PP. Conclusions: From these tests it emerges quite clearly that unpacked product has a shorter shelf life. In general, it can be said that the most important parameters to be considered in the shelf life of tomatoes are degradation and dehydration of the stem, where PLA packaging has a positive effect, followed only later by the dehydration of the fruit. Tests confirmed that the shelf life of tomatoes packed in PP is 11 days, which becomes 13 days if they are packed with PLA. For peppers, the factor limiting the shelf life is dehydration of the fruit, where PLA and PP behave similarly, followed by the degradation of the stem and crown, where PLA shows a positive influence. Shelf life is therefore limited to 8-9 days for both packaging solutions. However, given the same age, peppers wrapped in PLA show a better stem. The next target on Taghleef Industries’ agenda is to make a similar test on washed and cut fresh produce, another growing application where PLA could play a role. Given the very short shelf life of such products (normally no longer than 4-7 days), even 1-2 days extension would help considerably. www.ti-films.com www.eosta.com www.bio4pack.com Figure 1: Crown and Stem Index 6.0 Crown and stem index, [0-5] Firmness index, [02] Time, [day] Figure 3: Stem Index Stem index, [1-9] 5.0 4.0 3.0 2.0 1.0 0 0 2 4 6 8 10 12 14 Time, [Days] Figure 2: Firmness Index 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 2 4 6 8 10 12 14 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0 2 4 6 8 10 12 14 Time, [Days] PLA PP Ref. PLA PP Ref. PLA PP Ref. bioplastics MAGAZINE [06/11] Vol. 6 19
