Effects of mangrove apple (Sonneratia caseolaris) fruit extract on oxidative stability of palm olein under accelerated storage

M.H Yoong,T.M Tengku Rozaina

doi:10.26656/fr.2017.5(1).445

Abstract

Palm olein is commonly used in cooking and food processing, however, it is susceptible to oxidation due to its high unsaturated fatty acids content. An antioxidant is added to the oil by oil manufacturer to inhibit lipid oxidation and increase the shelf life of the oil. However, most of the antioxidants are synthetic antioxidants that may not be safe for consumption and decomposed at high temperature during frying or processing. In this study, the antioxidant properties of mangrove apple fruit extract (MAFE), as well as the oxidative stability of palm olein with and without MAFE, were investigated. Palm olein added with MAFE (100 and 200 ppm) and without MAFE were kept at 65°C in an oven for 24 days under accelerated storage. The results showed that MAFE contained high total flavonoid compound (26.06±0.30 mg QCE/g extract) and total phenolic compound (12.21±1.31 mg GAE/g extract). The IC50 values of antioxidant activities of MAFE calculated by DPPH and ABTS•+ were 31.16±0.76 µg/mL and 97.32±3.27 µg/mL, respectively. The palm olein samples added with MAFE showed significantly lower peroxide value, p-anisidine value, TOTOX value, conjugated dienes and conjugated trienes after 24 days of storage compared to the palm olein without MAFE (control sample). The oxidative stability of palm olein added with 200 ppm MAFE was higher compared to the palm olein added with 100 ppm MAFE and control sample. Therefore, MAFE has the potential to be used as a source of natural antioxidant to reduce the lipid oxidation and prolong the shelf life of food products.

Highlights

Palm olein is a common commercial vegetable oil in Malaysia
The total flavonoid content (TFC) in the fruit extract of Sonneratia caseolaris in the present study was considered high compared to other species
The high content TFC in the mangrove apple fruit extract (MAFE) in the present study was probably due to the presence of bioactive compound flavones and luteolin 7-O-β-glucoside responsible for intestinal α-glucoside inhibitory action as reported by Sadhu et al (2006) and Tiwari et al (2010)

Summary

Introduction

Palm olein is a common commercial vegetable oil in Malaysia. It is the liquid fraction obtained by fractionation of palm oil after crystallisation at a controlled temperature, while the solid fraction is called palm stearin (Soares et al, 2009). The palm olein has low oxidative stability due to it is high in unsaturated fatty acid content (55%), mainly oleic acid (C18:1n9) and linoleic acid (C18:2n6) (Che Man and Tan, 1999; Gan et al, 2005; Soares et al, 2009). According to Gan et al (2005), oxidation deteriorates oil or fat. It produced a pungent and offensive off-flavour, discolouration, polymerisation and destruction of vitamins (A, D, E, K and C), essential fatty acids, other nutrients, or enzymes by the production of the toxic or physiologically active compounds. Formation of numerous volatile and non-volatile compounds will be occurred due to the chemical reactions by oxidation, which included FFA, aldehydes, di- and mono-glycerides and polymeric triglycerides (Maskan and Horuz, 2017)

Objectives

Methods

Results