Oxidative stability of enriched walnut oil with phenolic extracts from walnut press-cake under accelerated oxidation conditions and the effect of ultrasound treatment

Bakkalbaşı E.

JOURNAL OF FOOD MEASUREMENT AND CHARACTERIZATION, vol.13, no.1, pp.43-50, 2019 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 13 Issue: 1
  • Publication Date: 2019
  • Doi Number: 10.1007/s11694-018-9917-y
  • Journal Name: JOURNAL OF FOOD MEASUREMENT AND CHARACTERIZATION
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.43-50
  • Keywords: Oxidative stability, Phenol enrichment, Ultrasonic maceration, Walnut oil, Walnut press-cake, ANTIOXIDANT, STORAGE, ACID, TOCOPHEROL, RESONANCE, PEROXIDE
  • Van Yüzüncü Yıl University Affiliated: Yes

Abstract

In this study, the effect of phenolic extract obtained from walnut press-cake on oxidative stability of walnut oil was evaluated. Besides this, the oxidative stability of ultrasound applied walnut oil with added press-cake, as a valuable source of phenolic compounds, was determined. Oxidative stability of walnut oils upon addition of phenolic extracts (50, 100 and 200mg/kg oil) and -tocopherol (100mg/kg oil) was monitored under accelerated oxidation conditions at 65 degrees C for 20day. Total phenolic content (TPC) of walnut press-cake and phenolic extract from walnut press-cake were 58207.3 and 332679.8mgGAE/kg, respectively. All concentrations of phenolic extracts significantly reduced the formation of oxidation products compared to control. Especially, the walnut oils enriched with 200mg/kg phenolic extract showed the highest oxidative stability. While direct enrichment using ultrasonic maceration (1:100) (walnut press-cake:walnut oil) caused a significant increase in TPC of walnut oil (from 9.76 to 78.80mg GAE/kg), ultrasonic macerated walnut oil had low oxidative stability. Results showed that 200mg/kg oil phenolic extracts from walnut press-cake can be successfully used as a natural antioxidant preparate to improve the oxidative stability of walnut oil.