Impact of nitrogen flushing and oil choice on the progression of lipid oxidation in unwashed fried sliced potato crisps

E Marasca,D Greetham,S.D Herring,I.D Fisk

doi:10.1016/j.foodchem.2015.11.136

E Marasca, D Greetham + Show 2 more

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https://doi.org/10.1016/j.foodchem.2015.11.136

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Journal: Food Chemistry	Publication Date: Nov 30, 2015
Citations: 16	License type: cc-by

Affiliation: University of Nottingham

Abstract

Unwashed, sliced, batch-fried potato crisps have a unique texture and are growing in popularity in the UK/EU premium snack food market. In this study, the storage stability of unwashed sliced (high surface starch) potatoes (crisps) fried in regular sunflower oil (SO) or in high oleic sunflower oil (HOSO) was compared over accelerated shelf life testing (45°C, 6weeks); with and without nitrogen gas flushing. Primary oxidation products (lipid hydroperoxides) were measured with a ferrous oxidation-xylenol orange (FOX) assay and volatile secondary oxidation products (hexanal) were quantified by using solid phase micro-extraction gas chromatography mass spectrometry (HS-SPME-GC/MS). Results revealed that crisps fried in SO were the least stable. Flushing the stored crisps with nitrogen gas proved to be effective in slowing down the oxidation rate after frying with sunflower oil, significantly stabilizing the crisps. However, crisps fried in HOSO were the most stable, with the lowest rate of development of oxidation markers, and this has previously not been shown for crisps with a high free starch content.

Highlights

Rancidity of edible oils and fatty foods due to lipid oxidation is a serious problem within the deep-frying industry (Gómez-Alonso et al, 2004; Matthäus, 2007; Sanches Silva, López Hernández, & Paseiro Losada, 2004; Sanches-Silva et al, 2004)
Hexanal was chosen as the primary indicator of secondary oxidation as it has previously been reported as being a good indicator of lipid oxidation in potato crisps (Azarbad & Jele, 2014; Jeon & Bassette, 1984; Sanches-Silva et al, 2004)
During weeks 3 to week 5, oxidation starts to occur and after week 5 there was a rapid production of secondary oxidation products, with headspace hexanal concentrations reaching 6700 ppb at week 6 for sunflower oil (SO) crisps, whereas high oleic sunflower oil (HOSO) crisps did not exceed 110 ppb at any time during the study

Summary

Introduction

Rancidity of edible oils and fatty foods due to lipid oxidation is a serious problem within the deep-frying industry (Gómez-Alonso et al, 2004; Matthäus, 2007; Sanches Silva, López Hernández, & Paseiro Losada, 2004; Sanches-Silva et al, 2004). Autoxidation, defined as the spontaneous reaction of atmospheric oxygen with lipids (St Angelo, 1996), is the most common process leading to oxidative deterioration and, as a consequence, to rancidity. Lipid hydroperoxides are the primary products of autoxidation and decomposition of the hydroperoxides leads to the formation of aldehydes, ketones, alcohols, hydrocarbons, volatile organic acids, and epoxy compound production; collectively these compounds are known as secondary oxidation products. The presence of these compounds accounts for the perception of off flavours, rancidity and loss of nutritional value in the food, which can eventually lead to rejection by the customer. Autoxidation of oil has been identified as the main cause of crisps quality deterioration (Choe & Min, 2007) and the reaction rate of autoxidation has been shown to strongly correlate with the shelf-life of the product (Frankel, 1980).

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