Smart and biodegradable labeling system using Butterfly Pea flower (Clitoria ternatea L.) Anthocyanin extract for monitoring of chicken meat freshness during chilled storage

Abstract

Chicken meat is highly perishable due to its high water content, which fosters microbial growth and spoilage, reflected by increased pH levels. Smart packaging, particularly colorimetric indicator films, offers a solution by visually monitoring meat freshness. Fresh chicken breast fillets were packaged with biodegradable films made from chitosan–PVA and infused with butterfly pea flower anthocyanin extract, which was prepared using ultrasonic-assisted ethanol extraction. The films were applied as freshness indicators and evaluated over 7 days of chilled storage through colorimetric analysis (Lab* values), total anthocyanin content, and pH sensitivity. Meat spoilage was assessed using Total Plate Count (TPC), Total Volatile Base Nitrogen (TVB-N), H₂S production, and the Postma test. The results showed that the anthocyanin content in the films decreased from 7.71 mg/L to 5.63 mg/L after seven days of storage. The pH, TPC, and TVB-N of chicken meat increased consistently during storage, reflecting spoilage and protein decomposition. The H2S and Postma test further validated the transition of meat freshness to spoilage. The meat remained fresh for 3 days, whereas a noticeable purple-to-green change of the smart label occurred on day 4 to 5. Colorimetric evaluation shows that freshness threshold pH (6.1) corresponded to L* < 9.98, a* > -0.22, and b* < 0.43. These results affirm the potential of butterfly pea flower anthocyanin-based films as effective, biodegradable indicators for monitoring chicken meat freshness.