Effects of thermal and high pressure treatments in color and chemical attributes of an oil-based spinach sauce

Abstract

We studied the effects of high pressure processing (HPP) on physico-chemical characteristics of an oil-based spinach sauce model system. Color, chlorophylls, ascorbic acid, polyphenoloxidase activity and lipid oxidation (measured as % oleic acid, peroxide value, and p-anisidine content) were evaluated. Multivariate analysis of variance (MANOVA) and principal component analysis (PCA) were used to elucidate the contribution of pressure and time on the observed changes. Both pressure and time had a significant effect, with pressure be responsible for most of lipid oxidation. Color attributes were preserved or even improved after HPP, with 500 MPa for 10 min the treatment with the best results. Higher recovery of ascorbic acid content, as well as chlorophylls a and b was achieved; HPP was not so effective in triggering lipid oxidation. A storage study for 21 days at 4 °C was performed in order to assess the long-term effects of thermal and HPP. During storage, lipid oxidation was drastically inhibited in HPP-treated samples. The degradation of PPO via high pressure was found to be reversible, since partial activity was recovered after 7 days. These preliminary results demonstrate the reliability of HPP as an alternative to thermal treatment to preserve physico-chemical characteristics of oil-based vegetable sauces.