Submitted to: Journal of Food Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/12/2014
Publication Date: 11/26/2014
Citation: Bett Garber, K.L., Watson, M.A., Lea, J.M., Bai, J., Baldwin, E.A., Raithore, S. 2014. Efficacy of monitoring the sensory taste characteristics in pomegranate juice with electronic tongue, and chemical measurements. Journal of Food Quality. 37(6):383-394. Interpretive Summary: Methyl Cellulose Percipitable Tannin Assay (MCPTA) assay was adapted for application with processed pomegranate juice to measure astringency. This test, along with soluble solids (Brix), titratable acidity (TA), pH, and an ‘electronic tongue’ instrument (e-tongue, a device that can determine a change in potential of electrodes exposed to juice samples) were evaluated for their utility to evaluate tastes in commercial pomegranate juice. In a single brand of juice measured at full strength, and diluted with water to 90%, 80%, and 70%, Brix correlated with sweet taste, the MCPTA method correlated with astringent feeling factor, and one e-tongue sensor negatively correlated with bitter taste and two e-tongue sensors positively correlated with bitter taste. When the tests were performed on six brands of commercial juice, the correlations were quite different. Brix weakly correlated with sweet taste. The pH and sour negatively correlated. The MCPTA assay moderately correlated with astringent feeling factor. None of the electronic tongue sensors correlated with any of the sensory taste attributes, but with further study, it may be effective for monitoring consistency between batches within a juice brand.
Technical Abstract: In addition to flavor attributes, pomegranate juices have sweet, sour, bitter tastes, astringent, and toothetch feeling factors. Many factors influence tastes and feeling factors. Measuring these attributes without a sensory panel makes economic sense. This investigation compares descriptive sensory evaluation with conventional and advanced methods. Brix degree (Brix), titratible acidity (TA), pH, a methyl cellulose precipitable tannin assay (MCPTA), and electronic tongue (e-tongue) techniques were compared with sensory attributes of six commercial pomegranate juices. The MCPTA assay correlated with astringent and bitter, while pH negatively correlated with sour. One juice brand was diluted with water to 70%, 80%, 90%, and a 100% juice sample had impressive correlations. Three e-tongue sensors correlated with bitter. One negatively correlated with sweet and three negatively correlated with astringent and one with bitter. Sensory panel evaluations and chemical measurements sufficiently differentiated brands. E-tongue sensors differentiated brands, and between bottles within brands.