Preparation and evaluation some properties of pH indicator film based on Arabic gum- Carboxy methyl cellulose composite film containing of Violet basil (Ocimum basilicum. L) Anthocyanin

Nowadays, pH indicator has engrossed wide attention because of its eligibility to monitoring shelf life. Intelligent packaging is authoritative of detecting, sensing, tracing, recording and communicating properties to provide information is communicated directly through color changes. In the meantime, natural anthocyanins are non-toxic, water- soluble and safe dye that are indicator to pH change. Anthocyanins are a large group of natural dyes. Some natural anthocyanin, such as anthocyanin extracted from mulberry, black bean, blueberry and violet basil (Ocimum basilicum) are used to spoilage monitoring. In present study, an intelligent pH-indicator film based on Arabic gum- Carboxymethyl cellulose incorporated with Violet basil (Ocimum basilicum. L) Anthocyanin was prepared and its properties including structural, physical, mechanical, thermal, antioxidant activity and color sensitivity to changing pH and ammonia gas were evaluated. 

For this purpose, at first anthocyanin of Violet basil was extracted and its color reactions were investigated. In next step, the extracted anthocyanin was added to Arabic gum- Carboxymethyl cellulose at different concentrations (40, 60 and 80 mg/100 g film formation solution) and their properties were evaluated. 

The results of FTIR and XRD tests showed that the extracted anthocyanin was successfully dissolved in the composite film. Addition of anthocyanin to film matrix led to increasing the WVP and antioxidant activity and decreasing the water contact angle, elongation at break (EB) and thermal properties. The tensile strength value of the prepared films increased from 19 to 23.64 MPa with increasing anthocyanin content from 0 to 60 mg/100 g film solution; but, it decreased with further increase of the anthocyanin content. Exposing the indicator films to ammonia gas and different pHs led to changing the color changes from red to yellow. These color variations of films were consistent with the color changes of the anthocyanin solution. This result indicates that the films prepared sensitive to pH change, and observed different color in films as the solution is changed from acidic to alkaline because causes its structural changes. The structure of anthocyanin is yellow salt ions in acidic solutions, is converted to quinoidal in weak alkaline solutions, and becomes unstructured in high pH solutions.In this study, pH indicator films were prepared based of Carboxymethyl cellulose and Arabic gum containing violet basil anthocyanin. The developed films are non-toxic and biodegradable and provide visible color response. Based on these results can be concluded that the indicator film prepared in present study could be used as intelligent food packaging for visual evolution of freshness/spoilage in food products