Anthocyanin Colorimetric Strip for Volatile Amine Determination

Abstract

Food freshness is one of the main concerns of consumers. Food spoilage is mainly caused by contamination and microbial growth in which the latter produces volatile amines in the process. Several methods have been used to determine volatile amines to indicate food freshness, and indicator films are deemed as the most time-efficient and economical. In this study, anthocyanin was extracted from mangosteen rind as a natural dye indicator and was incorporated in a chitosan/PVA polymer matrix. The film with different concentrations of anthocyanin extract (5%, 15%, and 25%) was prepared and tested for their sensitivity to 136 ppm ammonia vapor followed by colorimetric analysis using ImageJ software. The film with 25% anthocyanin yielded the most visible color change upon exposure to ammonia vapor. The color changed from pink to yellowish-brown within 14 minutes of exposure. The RGB-converted images of the film with 25% anthocyanin extract showed gradual loss of red coloration being replaced by cyan spots. FTIR spectra showed incorporation of anthocyanin to the chitosan/PVA matrix with the decrease in the intensity of the C-N stretching peak. Thermogravimetric analysis showed that the film has high thermal stability with onset temperature of 310.43°C. Thus, the film developed is an excellent candidate for optimization and production of a thermally stable amine detector for food products.

Utilising N‐glutaryl chitosan‐based film with butterfly pea flower anthocyanin as a freshness indicator of chicken breast

“…Indicator films with 15% v/v of BPA, particularly the ChGA–BPA film, exhibited higher sensitivity value compared with other anthocyanin concentrations and Ch–BPA film (Figure S3), indicating a more significant change in the film's colour when the R, G and B films were measured. The colour changes were induced by the presence of volatile NH 3 and H 2 O molecules, which undergo hydrolysis to form NH 4 + and OH − , causing an increase in environment pH that could be detected by the indicator films 55 . The lack of acetic acid in manufacturing also contributes to ChGA's increased sensitivity.…”

“…The colour changes were induced by the presence of volatile NH 3 and H 2 O molecules, which undergo hydrolysis to form NH 4 + and OH À , causing an increase in environment pH that could be detected by the indicator films. 55 The lack of acetic acid in manufacturing also contributes to ChGA's increased sensitivity. The presence of acetic acid in the Ch matrix causes the pH of the matrix's environment to be less likely to change to basic, making BPA colour change less likely.…”

Formulation of Gel Containing Phaseolus Vulgaris L. Extract and to Evaluate It’s Efficacy in the Management of Inflammation- A Single Arm Open Labelled Clinical Study

“…The observation that the extract maintains its stable colour indicates that anthocyanin is present. -When 1 ml of Phaseolus vulgaris L. extract is mixed with 2M NaOH, the extract's colour changes to show that anthocyanin is present [6,7].…”