Characterization and Effect of Refining on the Oil Extracted from Durum Wheat By-Products.

Giacomo Squeo,Marcello Greco Miani,Roccangelo Silletti,Graziana Difonzo,Giulia Napoletano,Antonella Pasqualone,Francesco Caponio

doi:10.3390/foods11050683

Giacomo Squeo, Marcello Greco Miani + Show 5 more

Open Access

https://doi.org/10.3390/foods11050683

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Abstract

Durum wheat is one of the most important cereal grains worldwide, used mostly for pasta making and bakery products. The by-products derived for the milling process, although very abundant, have only limited use. The aim of this work was to characterize the oils extracted from the by-products of debranning (DP) and milling processes (MP) of durum wheat and to follow the changes due to the refining process on the minor components. The results showed that DP had significantly higher oil content than MP, but it was characterized by a significantly lower amount of tocols. Polyunsaturated fatty acids content was similar (around 62% of total fatty acids). Consequently, a mixture of DP/MP (60/40 w/w) was chosen as a basis for further studies concerning the refining process. During refining, carotenoids almost disappeared while tocols were reduced by 24% on average. Free fatty acids, peroxide value, and oxidized triacylglycerols were significantly reduced by refining, while triacylglycerol oligopolymers were significantly higher than the crude oil. Durum wheat oil had an outstanding content of phytosterols and policosanols. Overall, the edible oil obtained from durum wheat after refining could be considered a good source of phytochemicals and could represent a valuable strategy to valorize the by-products from durum wheat mills.

Highlights

Since the production of durum wheat oil could represent an added value for the durum wheat milling industry, the aim of the present research was two-fold: (i) characterize the oils obtained from two different durum wheat by-products and (ii) evaluate the changes that occur during the oil refining process
Higher oil content was found in debranning process (DP), showing on average about 1.2 g of oil more than milling processes (MP) per 100 g of raw material
This result reflected the higher share of aleurone layer and germ particles, richer of lipids than endosperm [7], in the DP than in MP

Summary

Introduction

2.9–3.5% on a dry basis (d.b.) [1], with a fatty acid profile characterized by the prevalence of linoleic acid (about 53%) [2,3]. The latter is an essential fatty acid, which is the precursor of prostaglandins and membrane phospholipids involved in the regulation of blood lipid and cholesterol levels [4,5], not to mention the relevant content of tocopherols, which is another well known and appreciated characteristic of the wheat lipid fraction [6]. Germ and bran represent the main by-products of the milling industry, mostly destined for animal feeding [8]

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