Enhancing the stability of anthocyanins extracts through adsorption into nanoclays – development of a smart biohybrid sensor for intelligent food packaging or as natural food additive/preservative

Anthocyanins (ACNs) are bioactive compounds sensible to high temperature, light and highly reactive to pH changes. These natural pigments present different colors according to the environment pH, which enables its use as bio-based sensor to control microbial quality of fresh perishable foodstuff. In this work, a biohybrid material (BH) composed of anthocyanins extract from jambolan fruit (Syzygium cumini) stabilized by adsorption onto montmorillonite (Mt) was developed, characterized and tested to monitor freshness of shrimp. Anthocyanins were recovered from extract using Mt as adsorbent at pH 1.5, 2.5, and 3.5 and temperatures of 10 and 20 °C. Langmuir and pseudo-second-order kinetic models were adjusted to explain these adsorption mechanisms. ACNs’ adsorption increased with decreasing pH (p > 0.05) and increasing temperature. At 20 °C and pH 1.5, 93 % of ACNs were recovered from extract (adsorption of 212.04 mg of ACNs/g of Mt). The obtained BH presented good stability and color changing capacity when exposed to ammonia vapor at pH varying from 1 to 13. Freshness of shrimp was monitored with the BH, validating its potential to be used as ammonia sensing or pH indicators in intelligent packaging.