ARS | Publication request: ANALYSIS OF PHENOLIC COMPOUNDS: SAMPLE PREPARATION TO PATTERN RECOGNITION

Submitted to: UJNR Food & Agricultural Panel Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 15, 2004
Publication Date: December 11, 2004
Citation: Luthria, D.L., Mukhopadhyay, S. 2004. Analysis of phenolic compounds: sample preparation to pattern recognition. UJNR Food & Agricultural Panel Proceedings. p. 119-123.

Technical Abstract: Phenolics are important dietary constituents owing to their health-promoting qualities. It is critical to accurately determine the concentrations of the phenolics compounds in foods so that relationship between dietary intake and disease risk/incidence can be accurately established. This paper describes two topics: 1) Impact of sample preparation on assay of phenolic compounds, and 2) Development of a rapid UV method in conjunction with chemometrics analysis for differentiation of functional foods with varying phenolic content. Parsley (Petroselinum crispum) a phenolic enriched food was selected as a model substrate to evaluate the impact of sample preparation on assay of total phenolics (TP) from food matrices. Comparison of different extraction procedures and extraction solvents on isolation of phenolic compounds from parsley was evaluated. Extracts were analyzed for phenolic content by Folin-Ciocalteu assay. The extractions with Pressurized Liquid Extractor (PLE) were less time consuming with minimum sample handling and solvent exposure. The yields of phenolic compound extracted with PLE were better or comparable than the other four classical extraction procedures (sonication, stirring, shaking and vortexing). Optimum extraction efficiency of phenolic compound was obtained when parsley flakes were extracted with 50% aqueous ethanol with four extraction cycles. Four broccoli samples grown under different conditions with varying selenium concentrations were used as model substrates for development of rapid analytical method for differentiation of foods based on TP content. Freeze dried samples were extracted with methanol:water (60:40, % v/v). UV spectral analysis, in conjunction with principal component analysis and the hierarchical cluster analysis, provided a simplified procedure for differentiation of broccoli samples grown under different environmental conditions. This simplified cost effective procedure can be extended for classifying functional foods with enhanced nutritional traits from conventional foods.