Chemical and structural variations in hazelnut and soybean oils after ozone treatments

H. Uzun,E. Ibanoglu,S. Ibanoglu,E. G. Kaynak

doi:10.3989/gya.1098171

Abstract

In the present work, the effect of ozone treatments on the structural properties of soybean oil (SBO) and hazelnut oil (HO) were investigated. The study presents the findings and results about the oxidation of HO and SBO with ozone, which has not been fully studied previously. The HO and SBO were treated with ozone gas for 1, 5, 15, 30, 60, 180 and 360 min. The ozone reactivity with the SBO and HO during the ozone treatment was analyzed by 1H, 13C NMR, FTIR and GC. The iodine value, viscosity and color variables (L*, a* and b*) of untreated and ozone treated oils were determined. Reaction products were identified according to the Criegee mechanism. New signals at 5.15 and 104.35 ppm were assigned to the ring protons of 1,2,4- trioxolane (secondary ozonide) in the ozonated oils in 1H and 13C NMR, respectively. Ozonated oils exhibited peaks at 9.75 and 2.43 ppm in 1H and NMR, which corresponded to the aldehydic proton and α-methylene group and to the carbonyl carbon, respectively. The peak at 43.9 ppm in 13C NMR was related to the α-methylene group and to the carbonyl carbon. The new signals formed in the ozonation process gradually increased with respect to ozone treatment time. After 360 min of ozone treatment, the carbon-carbon double bond signal, which belongs to the unsaturated fatty acids, disappeared completely in the spectrum. An increase in viscosity, a decrease in iodine value and a dramatic reduction in b* of the oil samples on (+) axis were observed with increased ozone treatment time.

Highlights

While thermal methods can effectively eliminate pathogens, non-thermal technologies provide the potential advantages of maintaining physical, chemical, and sensory attributes and ensuring the raw characteristics of food products preferred by some consumers (Prakash, 2013)
Iodine value (IV) is often used to determine the amount of unsaturated bonds in the oils which react with iodine compounds
Since ozone reacted with carbon-carbon double bonds in the unsaturated fatty acid, this aspect may represent a measurement of residual double bonds

Summary

Introduction

While thermal methods can effectively eliminate pathogens, non-thermal technologies provide the potential advantages of maintaining physical, chemical, and sensory attributes and ensuring the raw characteristics of food products preferred by some consumers (Prakash, 2013). Ozone application is a relatively new method in food processing It is a viable disinfectant for maintaining the microbiological safety of food products because of its substantial reactivity, penetrating ability and ability to decompose spontaneously to a nontoxic product (i.e., O2) (Atungulu and Pan, 2012). It received the GRAS (generally recognized as safe) status for use as disinfectant and sanitizer in 1997 (USDA, 1997). The analyses related to these reactions provide useful information on the functional group changes during ozonation as well as the identification of the products, according to the Criegee mechanism regarding the formation of ozonides from alkenes and ozone. The initial pathway of formation of the primary ozonide is a 1,2,3 trioxolane. Pryor, (1994)

Methods

Results

Conclusion