This work presents a bibliographic review about almond kernel non-lipid components, in particular about the protein fraction, the carbohydrates and the mineral fraction. In addition, other fat-soluble phytochemicals which are present in minor concentrations but show important antioxidant activities are reviewed. Almond kernel is a rich protein food (8.4–35.1%), in which the globulin–albumin fraction dominates, followed by glutelins and prolamins. Within the almond kernel protein profile, amandine dominates. Free amino acids represent a small amount of the total nitrogen quantity, highlighting the presence of glutamic acid and aspartic acid, followed by arginine. Carbohydrates that appear in almond kernels (14–28%) are soluble sugars (mainly sucrose), starch and other polysaccharides such as cellulose and non-digestible hemicelluloses. Regarding the mineral elements, potassium is the most common, followed by phosphorus; both macronutrients represent more than 70% of the total mineral fraction, without taking into account nitrogen. Microminerals include sodium, iron, copper, manganese and zinc. Within the phytochemical compounds, tocopherols, squalene, phytosterols, stanols, sphingolipids, phospholipids, chlorophylls, carotenoids, phenols and volatile compounds can be found.

Defatted almond meal (DAM) is an useless biomass waste obtained after oil extraction. The substrate designed for mushroom cultivation is achieved through a controlled composting process from agricultural by-products (chicken manure and wheat straw). This work shows the potential of DAM as efficient compost supplement for culturing the species Agaricus bisporus (J.E. Lange) Imbach and Pleurotus ostreatus (Jacq.) P. Kumm. Supplementation during A. bisporus cultivation results in larger mushrooms with a firmer texture and higher dry matter and protein contents in comparing with the non-supplemented substrate. In P. ostreatus, supplementation at a dosage of 15 g kg -1 provided a yield improvement up to 31.8%, compared to the control without supplement. The supplementation with DAM supposed equivalent or better yield than the commercial supplements. Therefore, the technique developed assessed good agronomic potential for application of DAM at the commercial scale in P. ostreatus cultures, adding value to a worthless organic by-product.Reciclagem de farinha de amêndoa desengordurada com resíduo de biomassa para uma nova suplementação nutricional em cogumelos comestíveis cultivados RESUMO. A farinha de amêndoa desengordurada (DAM) é um resíduo de biomassa inútil obtido após extração de óleo. O substrato designado para o cultivo de cogumelos é formulado através de um processo de compostagem controlado utilizando subprodutos agrícolas (cama de frango e palha de trigo). Este trabalho demosntra o potencial da DAM como um suplemento de composto eficiente para o cultivo das espécies Agaricus bisporus (J.E. Lange) Imbach e Pleurotus ostreatus (Jacq.) P. Kumm. A suplementação durante o cultivo de A. bisporus resulta em cogumelos maiores com textura firme e elevado teor de matéria seca e proteína, em comparação com o substrato não suplementado. Em P. ostreatus, a suplementação utilizando a dosagem de 15 g kg -1 proporcionou um aumentono rendimento para 31,8%, em comparação com o substrato nãosuplementado. A suplementação com DAM proporcionou rendimento equivalente ou melhor do que os suplementos comerciais. Portanto, a técnica desenvolvida avaliou o bom potencial agronômico para aplicação de DAM na escala comercial em culturas de P. ostreatus, agregando valor a um subproduto orgânico sem valor.Palavras-chave: farinha de amendoa desengordurada; rendimento; qualidade; Agaricus bisporus; Pleurotus ostreatus; resíduos reciclados.

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.

SUMMARY:In this paper the extraction methods of virgin almond oil and its chemical composition are reviewed. The most common methods for obtaining oil are solvent extraction, extraction with supercritical fluids (CO 2 ) and pressure systems (hydraulic and screw presses). The best industrial performance, but also the worst oil quality is achieved by using solvents. Oils obtained by this method cannot be considered virgin oils as they are obtained by chemical treatments. Supercritical fluid extraction results in higher quality oils but at a very high price. Extraction by pressing becomes the best option to achieve high quality oils at an affordable price. With regards chemical composition, almond oil is characterized by its low content in saturated fatty acids and the predominance of monounsaturated, especially oleic acid. Furthermore, almond oil contains antioxidants and fat-soluble bioactive compounds that make it an oil with interesting nutritional and cosmetic properties. KEYWORDS:Almond; Chemical composition; Extraction; Oil; Quality RESUMEN: Aceite de almendra virgen: Métodos de extracción y composición. En este trabajo se revisan los métodos de extracción del aceite de almendra virgen y su composición química. Los métodos más habituales para la obtención del aceite son la extracción con disolventes, la extracción con fluidos supercríticos (CO 2 ) y los sistemas de presión (prensas hidráulica y de tornillo). El mayor rendimiento industrial, pero también la peor calidad de los aceites, se consigue mediante el uso de disolventes. Además, los aceites obtenidos por este método no se pueden considerar vírgenes, pues se obtienen por medio de tratamientos químicos. La extracción con fluidos supercríticos da lugar a aceites de mayor calidad pero a un precio muy elevado. La extracción mediante prensado se convierte en la mejor opción de extracción, al conseguir aceites de alta calidad a un precio asequible. En cuanto a su composición química, el aceite de almendra se caracteriza por su bajo contenido en ácidos grasos saturados y el predominio de los monoinsaturados, en especial en ácido oleico. Además, el aceite de almendra contiene compuestos bioactivos liposolubles y antioxidantes que lo convierten en un aceite con interesantes propiedades nutricionales y cosméticas.

PurposeAlmond oil is a gourmet product with functional food characteristics owing to its high almond oil content and high nutritional quality. One of the primary constraints on its production is the lack of information regarding oil extraction from an industrial perspective, including by-products generation.Design/methodology/approachThe performance, quality and composition characteristics were analyzed, both from the physical-chemical and organoleptic point of view, of the almond oils obtained through two pressure systems: screw press (SP) and hydraulic press (HP). To ensure the success of almond oil production at a commercial scale, in this work, an economic study of the costs of the process was carried out as a complementary part of optimizing the production of virgin almond oil.FindingsPhysicochemical analysis showed little difference, just in total sterols (HP 2069, SP 2153) and some quality indexes (K232: HP 1.63, SP 2.13; peroxide index: HP 1.74, SP 0.95), in contrast to sensory analysis. Consumer judges valued roasted almond oil extracted using a HP the best. The production cost of the oil extracted with the SP was €23.05/l. With the HP it was €25.13/l, owing to the lower oil yield in the extraction. The most expensive treatment was for the HP with toasted almonds (€27.76/l), owing to the greater need for processing.Originality/valueProduction costs derived from the method used have received little attention. This paper presents data that allow for the transference between academic and industrial ambit and their economic viability.