No abstract

Despite its high nutritional value, tiger nut oil is hardly used in food industries compared to other vegetable oils such as olive and peanut oil. However, its benefits are increasingly being recognized, including its stability and similarity to olive oil in particular. This review discusses its composition, physico‐chemical properties and economic potential. Literature reveals that tiger nut oil shares a similar fatty acid profile with olive, avocado and hazelnut oil. Its low content of polyunsaturated fatty acid, tocopherol and phytosterol contributes to its high stability. When compared to soy bean oil, its phospholipids composition (3.1–5.4%) is higher. Its iodine and acid values reflect its quality at 76.60 and 0.03 mg KOH/g oil, respectively. Roasted tiger nut oil was found to contain vanillin and to a lesser extent 2, 3‐dihydro‐3, 5‐dihydroxy‐6‐methyl‐4H‐pyran‐4‐one and 5‐ethylfurfural as key odorants contributing to the overall aroma of the oil. Its low viscosity makes it suitable for use in coating industry and as fuel. In‐depth studies on the oils' constituents are on‐going but efficient and environmentally friendly extraction techniques are needed. Based on the available data, tiger nut oil has been established as an oil of good nutritional value which may be exploited to the great benefit of growers, processors and dealers of the tuber. This review discusses the composition, physico‐chemical properties and economic potential of tiger nut oil.

Tiger nut (Cyperus esculentus) tuber contains oil that is high in monounsaturated fatty acids, and this oil makes up about 23% of the tuber. The study aimed at evaluating the impact of several factors and enzymatic pre-treatment on the recovery of pressed tiger nut oil. Smaller particles were more favourable for pressing. High pressure pre-treatment did not increase oil recovery but enzymatic treatment did. The highest yield obtained by enzymatic treatment prior to mechanical extraction was 33% on a dry defatted basis, which represents a recovery of 90% of the oil. Tiger nut oil consists mainly of oleic acid; its acid and peroxide values reflect the high stability of the oil.

Tiger nut oil is a novel oil that requires more research data on its characteristics. In this study, the oil was extracted using both enzyme-aided pressing (EAP) and aqueous enzymatic extraction (AEE) methods. Using enzymes as a pre-treatment prior to mechanical pressing increased the concentration of some phenolic acids and tocopherols present in extracted oils compared to controls. High pressure processing as a pre-treatment before aqueous enzymatic extraction also enhanced tocopherols and total polyphenolic content in oils. The percentage free fatty acid and peroxide values indicated that under the initial extraction parameters, the oils were stable and they all met the standards for virgin olive oil set by the International Olive Oil Council. Residual meals from both extraction processes contained low protein contents ranging from 2.4 to 4.6 %. Additionally, EAP and AEE meals contained low DP (degree of polymerisation) sugars that appeared as 1-kestose (DP3) and nystose (DP4). EAP had the highest total DP3 and DP4 sugar content of 82.5 mg/g. These sugars would need further assessment to verify their identity and determine their suitability as a potential food.

High pressure processing (HPP) was applied as a pre-treatment on Moringa oleifera (MO) kernels, for the first time, prior to aqueous enzymatic extraction (AEE) of the MO oil, and the effect of this pre-treatment is reported in terms of the free oil recovery and the nature of the cream emulsions formed. The HPP pre-treatments (50-250 MPa, 20-60 ⁰C, 10-60 min) generally resulted in higher free oil recoveries and thinner emulsion layers from ground-sieved kernels than the whole kernels. Optimization of the HPP parameters indicated linear increment in free oil recovery with increase in temperature and time, but not the pressure level. Without the pre-boiling step in the AEE process, the use of HPP pre-treatment at 50 MPa and 60 ⁰C for 35 min resulted in approximately 73% (w/w) free oil recovery with thinner emulsion layer than the use of AEE alone. These findings highlighted the ability of HPP in altering the MO protein structure into a form of less emulsifying functional properties, thus further de-emulsification method may not be necessary.