Immobilization of Echium amoenum anthocyanins into bacterial cellulose film: A novel colorimetric pH indicator for freshness/spoilage monitoring of shrimp

• Published in: Food control Vol. 113; p. 107169
• Main Authors: Mohammadalinejhad, Samira, Almasi, Hadi, Moradi, Mehran
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2020
• Subjects: anthocyanins; Bacterial cellulose; cellulose; cold storage; color; Colorimetric indicator; colorimetry; crystal structure; Echium amoenum; films (materials); flowers; Food spoilage; Fourier transform infrared spectroscopy; freshness; Intelligent packaging; monitoring; natural dyes; Natural extract; packaging; plate count; scanning electron microscopy; shrimp; Shrimp freshness; spoilage; total volatile basic nitrogen; X-ray diffraction; Colorimetric indicator; Bacterial cellulose; Food spoilage; Natural extract; Shrimp freshness; Intelligent packaging
• DOI: 10.1016/j.foodcont.2020.107169
• ISSN: 0956-7135

The aim of this research was to develop an intelligent pH-sensitive indicator based on natural dye extracted from Echium amoenum flowers (EAE). The indicator was fabricated by incorporation of EAE into bacterial cellulose (BC) film, then characterized and used to monitor the freshness of packaged shrimp. The FT-IR analysis suggested the formation of new interactions between BC and anthocyanins. Evidence of disruption of crystalline structure and alteration of the morphological characteristics of BC film after immobilization of the EAE were observed by XRD and FE-SEM analyses, respectively. The fabricated BC-EAE indicator clearly responded to pH by changing color from red to yellow over the pH range of 2–12. The total volatile basic nitrogen (TVB-N), total viable count (TVC) and the pH of shrimp were monitored during refrigerated storage for 4 days, and the color changes of the indicator were recorded simultaneously. Visually-distinguishable color changes were observed as the shrimp aged, i.e. fresh (violet), use soon (gray), and spoiled (yellow) shrimp. These color changes were in accordance with the TVC and TVB-N values of the shrimp. The fabricated BC-EAE indicator visually identified shrimp spoilage by color changes, suggesting the suitability of E.amoenum anthocyanins as a novel pH-sensitive dye for intelligent packaging of protein-rich food. •Echium amoenum extract (EAE) was introduced as a novel colorimetric pH indicator.•BC-EAE exhibited distinguishable color changes from violet to yellow through pH 2–12.•The freshness monitoring of packaged shrimp was achieved with rapid response of indicator.•High color stability and unchanged morphological characteristics are advantages of BC-EAE.•Fabricated indicator exhibited high correlation of EAE color and quality attributes of shrimp.