Abstract
Almond is the most cultivated nut throughout the world. The oil content of almonds in most varieties exceeds 50%, which encourages the oil extraction to be used in gastronomy or in the cosmetic industry. The preferred system to extract almond oil is by means of pressure, which leads to obtaining a virgin oil ready for consumption. In this work, almond oil has been obtained using two pressure systems: screw press (SP) and hydraulic press (HP). The performance of both methods, as well as their influence on quality and composition characteristics of the almond oils obtained are analyzed from both a physical-chemical and sensory point of view. From an industry perspective, the highest oil yield is obtained with the SP when it operates at temperatures of 100–150 °C. Regarding the quality and chemical composition, the oils obtained by HP showed better quality indices, as they are subjected to a less aggressive treatment without influence of temperature, but lower content in total sterols. Fatty acid pattern, characterized by the predominance of unsaturated fatty acids (>90%), was not affected by the pressing system. The different operational conditions tested did not greatly affect the performance or composition of the oils obtained, but sensory tests showed two clearly differentiated products, the oil obtained by HP and that obtained by SP, according to consumer preferences. The defatted almond flours obtained as a by-product of the oil extraction process are characterized by a high content in protein and fiber, and a higher content in fat when the flour is produced from the pressing cake of HP.
Highlights
The almond is the most important nut crop in the world in terms of its commercial production, which exceeds 3 million tons annually [1]
Both extraction methods were tested under different conditions: in the hydraulic press different combinations were made according to pressure applied and time, and in the screw press combinations of extraction temperature and rotation speed were tested
The oil obtained in the screw press is significantly higher (49.18% on average) than that obtained with the hydraulic press (37.94%)
Summary
The almond is the most important nut crop in the world in terms of its commercial production, which exceeds 3 million tons annually [1]. Similar to many other nuts, the almond stands out for its high oil content (40–67%), which is characterized by a fatty acid profile with a low percentage of saturated fats, and where monounsaturated fatty acids predominate [5]. Almond consumption has been associated with many health benefits [7], especially related to the reduction of cardiovascular disease risk, and with effects on other pathologies, such as hypertension, diabetes mellitus, or metabolic syndrome. These activities are generally attributed to the lipid fraction, where the fatty acid profile has a predominant role, and minor compounds such as polyphenols and phytosterols may be involved
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