Anthocyanin based freshness indicator for intelligent packaging application

Abstract

In the current study, anthocyanin (AC) was extracted from the seed coat of red kidney bean for preparing pH sensitive freshness indicator. Bromocresol purple (BCP) was used as reference indicator. Ginger prawn , an endemic species of the Gulf of Kutch, was collected from Surajbari . The whole prawns were packed inside nylon-EVOHpolyethylene bags (one group under air and another under vacuum) along with freshness indicators and stored at 4 oC. On 0th day, pH, TMA-N and TVB-N values of ginger prawn were 5.09, 1.85 and 12.9, respectively. During storage, pH values of aerobically packed prawns (AP) increased and reached a value of 7.8 on 6th day. At the end of 9 days of chilled storage, 8.41 was the pH of vacuum packed sample (VP). Over the period of storage, colour of the freshness indicating dyes changed with increase in pH and volatile base formation. On the day of sensory rejection of samples, BCP was turned from yellow to purple and colour of AC changed from pink to blue-green, revealing its efficiency for freshness prediction, which will enable the consumers to judge the quality of fish.