Review about Non-Lipid Components and Minor Fat-Soluble Bioactive Compounds of Almond Kernel

Abstract

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.

Influence of Pressure Extraction Systems on the Performance, Quality and Composition of Virgin Almond Oil and Defatted Flours

“…Phenolic compounds also have important biological activities due to their high antioxidant capacity, for which healthy effects have been described [ 6 ]. Several in vitro assays developed to assess total antioxidant capacity in foods have focused on the effect of polyphenols.…”

“…In addition, 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 oil also contains minor phytochemical compounds such as tocopherols, sterols, or phenolic compounds with biological activity and antioxidant properties [ 6 ].…”

Variability of Chemical Profile in Almonds (Prunus dulcis) of Different Cultivars and Origins

“…Carbohydrates are present in almond kernels in the 2–12% range [ 45 ], mainly as soluble sugars. Sucrose and raffinose are the main compounds of this group, representing about 90% of the total sugars level when the seeds are ripe [ 30 , 31 , 46 ].…”

“…Almond fibre is mainly composed of cellulose, hemicelluloses, and lignin, which account up to 80% of the total fibre content of kernels [ 45 ]. It is important to note that different methods of determination of fibre content have been used, mainly neutral detergent fibre, acid detergent fibre, crude fibre, and total dietary fibre, which affect the values reported.…”

“…The almond kernel is considered a good source of minerals [ 4 , 45 ]. The majority of the studies provide data on major elements: K, P, Ca, and Mg (found at levels above few hundreds mg/100 g wet basis), and some minor elements: mainly Na, Fe, Cu, Zn, and Mn (usually in the mg/100 g wet basis level or below) [ 4 , 35 ].…”