Strengthening the texture of dried guava slice by infiltration of phenolic compounds

Phenol–pectin interaction was highlighted in plant texture maintenance during thermal processing. However, neither application nor significantly involved phenolic compounds other than ferulic acid have been reported. The aim of this study is to evaluate the contribution of this crosslink in strengthening the texture of guava slices with six phenolic compounds during processing. Results showed that samples treated with phenolics bearing a carboxyl group exhibited significantly higher hardness than control samples. Further pectin fractionation analysis and binding capacity tests in an artificial model system proved the existence of a higher ratio of hard pectin and greater binding capacity in phenolic treated samples. Sephadex G-75 purification and observation through fluorescence microscope and SEM confirmed the existence of phenol–pectin complex. Contribution of binding capacity to strengthen hardness was found highest in gallic acid treated samples, followed by those treated with ferulic acid, caffeic acid, coumaric acid, cinnamic acid or catechin. FRAP reducing power and DPPH scavenging ability showed the similar tendency. These results indicated that phenolic infiltration might improve the texture and antioxidant capacity of processed guava slices through phenol–pectin interaction.