Characterization and Demulsification of the Oil-Rich Emulsion from the Aqueous Extraction Process of Almond Flour

Fernanda F G Dias,Ameer Y Taha,Neiva M De Almeida,Thaiza S P De Souza,Juliana M L N De Moura Bell

doi:10.3390/pr8101228

Fernanda F G Dias, Ameer Y Taha + Show 3 more

Open Access

https://doi.org/10.3390/pr8101228

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Abstract

The aqueous extraction process (AEP) allows the concurrent extraction of oil and protein from almond flour without the use of harsh solvents. However, the majority of the oil extracted in the AEP is present in an emulsion that needs to be demulsified for subsequent industrial utilization. The effects of scaling-up the AEP of almond flour from 0.7 to 7 L and the efficiency of enzymatic and chemical approaches to demulsify the cream were evaluated. The AEP was carried out at pH 9.0, solids-to-liquid ratio of 1:10, and constant stirring of 120 rpm at 50 °C. Oil extraction yields of 61.9% and protein extraction yields of 66.6% were achieved. At optimum conditions, enzymatic and chemical demulsification strategies led to a sevenfold increase (from 8 to 66%) in the oil recovery compared with the control. However, enzymatic demulsification resulted in significant changes in the physicochemical properties of the cream protein and faster demulsification (29% reduction in the incubation time and a small reduction in the demulsification temperature from 55 to 50 °C) compared with the chemical approach. Reduced cream stability after enzymatic demulsification could be attributed to the hydrolysis of the amandin α-unit and reduced protein hydrophobicity. Moreover, the fatty acid composition of the AEP oil obtained from both demulsification strategies was similar to the hexane extracted oil.

Highlights

Almond (Prunus dulcis L.) is the most widely consumed tree nut in the United States, with the state of California being responsible for 100% of the U.S almond supply and 80% of the world’s almond production [1]
These results are in agreement with those obtained at laboratory scale (0.07 kg of almond flour), where oil and protein extraction yields of 69.8 and 64.8%
Chemical and enzymatic demulsification strategies significantly increased the recovery of almond oil extracted by the aqueous extraction process

Summary

Introduction

Almond (Prunus dulcis L.) is the most widely consumed tree nut in the United States, with the state of California being responsible for 100% of the U.S almond supply and 80% of the world’s almond production [1]. The consumption of almonds has been linked to nutritional and health benefits arising from its composition [2,3]. Almonds are rich in oil, protein, and carbohydrates, as well as micronutrients such as vitamin E, manganese, magnesium, copper, phosphorus, fiber, and riboflavin [4]. The lipid content in almonds is around 55% and consists mainly of polyunsaturated oleic and linoleic fatty acids [4,5]. Almonds contain a high protein content (27%), which contributes significantly to nutrition, flavor, and other important functional properties when used as the main ingredient in several food products [6].

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