Fabrication and design of poly(l-lactic acid) membrane for passive MAP packaging of Brassica chinensis L.

PLD L copolymers were synthesized from physically stable rigid poly(l-lactic acid) (PLLA) and a few different molecular weights of polydimethylsiloxane (PDMS) to increase the O and CO permeabilities of PLLA films and make them acceptable for packaging highly respirable products. The effect of PDMS on the morphology, mechanical properties, and gas permeability of PLD L was investigated. Copolymers showed approximately 10 times the fracture strain and 1.7 times the CO and O permeabilities of neat PLLA. Additionally, PLD L maintained an increased CO /O perm-selectivity consistent between 5 and 40°C. Passive modified atmosphere packaging of Brassica chinensis L was developed to assess the membrane's impact on headspace gas inside the package. The results showed that poly(amide)/poly(ethylene) packaging with 48 cm PLD L membrane as a breathing window can provide 50 g B. chinensis L. with a healthy atmosphere of 3%-8% O and 5%-8% CO between 6 and 22 days. Vegetables packaged in PLD L had the lower respiration rate, lower nitrite contents, and less proliferation of microorganisms. Moreover, a suitable atmosphere kept vegetables with higher ascorbic acid and a good appearance after more than 2 weeks of storage at 5°C. PRACTICAL APPLICATION: The permeability of the PLLA-based membrane can be adjusted for the breathable window membrane of sealed fresh products. In the future, several types of film could be developed to match the respiratory and metabolic characteristics of different kinds of products. Such PLLA-based specialized membranes can refine the fresh-keeping function and be more attractive to the customer.