Polylactic acid, as a biodegradable polymer derived from renewable resources, is increasingly widely used in the food packaging industry due to its transparency, renewability, and food safety. Recently, an article published in the journal "Frontiers in Chemical Science and Engineering" (in English) revealed the innovative achievements and practical prospects of the application of polylactic acid in this field. 

It is introduced that polylactic acid is a bioplastic made from renewable resources such as corn and wheat. It can decompose under controlled composting conditions. Moreover, it not only has the transparency and heat insulation properties comparable to traditional plastics, but also has made significant progress in the field of food safety. 

For a long time, polylactic acid has had problems with high brittleness and poor heat resistance in its applications. Researchers have developed polylactic acid composite films through composite modification technology. These films have a transparency similar to that of ordinary glass, yet their ultraviolet blocking rate is higher than that of traditional polyethylene terephthalate plastics. Beverage bottles made from this material can not only clearly display the contents but also protect the quality of the beverages like a "sunscreen umbrella". 

The researchers also developed a biodegradable polylactic acid packaging film with long-lasting antibacterial and antioxidant properties by combining natural antioxidants (such as tea polyphenols and rosemary extract) and antibacterial agents (such as cinnamaldehyde and eugenol). Experimental data show that this intelligent packaging can significantly reduce the total number of bacteria on the surface of fresh meat, effectively inhibit the oxidation of oils, and act as a "preservation barrier" for the food. 

In the field of controlled atmosphere packaging, polylactic acid materials demonstrate precise "breathing regulation" capabilities. By controlling the oxygen permeability, this "breathing packaging" can significantly reduce the spoilage rate of perishable fruits, with the effect far exceeding that of traditional plastic packaging. 

To further ensure food safety, polylactic acid materials are evolving towards an "active defense" approach - researchers are attempting to embed pH indicator substances into packaging films. When the food deteriorates, the packaging will send out a "spoilage alert" through color changes, just like equipping food with a "24-hour safety officer". 

This study suggests that polylactic acid, due to its excellent mechanical properties, high transparency, and abundant resources, has become an ideal material for food packaging. In the future, the degradation process of polylactic acid needs to be systematically optimized to meet the ecological and sustainability standards required for its widespread use in the food packaging field.