1. Introduction
Moringa oleifera, known as “Moringa” or “Malunggay” is an Indian tree that also grows in Asia, Africa, Southamerica, the Caribbean and Oceania. The oil extracted from Moringa is known as Ben oil and reportedly contains 70% of oleic acid, an 18-carbon long monounsaturated fatty acid (MUFA). Since the oleic acid has good oxidative stability when compared with polyunsaturated fatty acids (PUFAs), it has found use in the food industry, as it allows for longer storage and high-temperature frying processing. It also has uses in medicine and water treatment.
According with Abdulkarim et al. [1] Ben oil is more stable than canola oil, soybean oil, and palm oil when used in frying. Blending Ben oil with sunflower oil and soybean oil enhances the oxidative stability of the mixture. Mani et al. [2] say that comparing its chemical properties, Moringa seed oil is considered equivalent to olive oil, and may be used for human consumption. Also, the oil from Moringa seeds has shown the strongest antifungal activity against a zoophilic dematophyte caused marked inflammatory reactions in humans [3].
Another potential use of Moringa oil is as biodiesel feedstock. Currently, there is a nascent biodiesel industry in the Yucatan Peninsula, Mexico, that has been active for the last 2 - 3 years. Several groups are trying to obtain biodiesel from vegetable oils, especially Jatropha curcas, and from waste cooking-oil. As an alternative source of oil, Moringa seeds have been proposed as a potential source to complement the mentioned feedstock.
In this study, experimental results of solvent Soxhlet extraction using n-hexane and ethanol, and supercritical extraction with CO2 are reported. Solvent extraction has been reported by Mani et al. [2] using n-hexane, petroleum ether and acetone. Experimental Soxhlet extraction using n-hexane and ethanol, and also supercritical extraction with CO2 on Moringa seeds have been reported by Nguyen et al. [4]. Extraction of essential oil components using supercritical fluids has received much attention in the past years because it presents an alternative to solvent extraction or steam distillation. Sovova and Stateva [5] recently review the field of supercritical extraction of vegetable materials and say that industrial applications are increasing. It is hoped that the results will provide information to compare Moringa seeds cultivated in Yucatan-Mexico as raw material candidate for vegetable oil and biodiesel.
2. Materials and Methods
2.1. Material and Sample Preparation
Moringa seeds from wild trees in the Yucatan Peninsula, Mexico were used. The seeds shown in Figure 1 were separated from the membranes and milled by three different methods: ball mill, electrical grinder (Moulinex Pikalica), and hand-operated mortar.
Each method resulted in a powder with a size distribution, which was characterized by sieving. The average diameter for supercritical extraction was 0.46 mm and the averaged diameter for solvent extraction was 0.97 mm. The humidity of Moringa oleifera powder was 5. 84% and then do not requires drying.
Supercritical extraction was performed with industrial grade CO2 (99.9%), and dry air was used as the service gas. Both were supplied by Praxair. For the solvent extraction Hexane and ethanol were provided by J. T. Baker.
2.2. Soxhlet and Supercritical Extraction Method
Figure 2(a) shows the Soxhlet apparatus used for solvent extraction (SE) where 10 grams of powder of Moringa oleifera was treated with 210 ml of ethanol or hexane during 6 hours. The solvent was eliminated in a rotavapor and the yield was calculated as grams of extract divided by grams of original powder in a dry basis.