Garlic Oil Purification By Molecular Distillation And Microencapsulation By Spray-drying

Garlic (Allium sativum) is a species in the onion family Alliaceae , which is widely used as spices. And as the main producing country of the garlic, China is rich in garlic resource. Garlic is more and more popular with the consumers due to its biological functions, such as antimicrobial, antithrombotic, anticancer, antioxidant and improving immune-system as well as ability to lower serum lipid and glucose levels and blood pressure. And previously studies show that those biological functions of garlic are mainly attributed to allicin in it. Research on the further processing of the garlic is meaningful, which provides a more widely prospect of garlic products.Allicin extracted by supercritical CO₂ can be purified by molecular distillation (MD). Compared with other methods, MD has many advantages. It can be used to purify mixtures whose boiling points are high, having heat sensitivity and easily oxidized. MD can avoid the oxidation of allicin and protect the biological activity of allicin.Preparation of garlic oil into microcapsule, that is to say, making garlic oil into powder, could avoid garlic oil from auto-oxidation and rancidity. Not only were the inherent characteristics of the garlic oil maintained, but also the defects of the liquid garlic oil were made up for. There were many ways to prepare garlic oil microcapsule, but spray-drying technology was selected for its low-cost, simple and continuous production. Now spray-drying technology was widely used in microencapsulation of food production.Innovational features of this study were: utilization of modified starch,β- cyclodextrin and sodium caseinate as composite wall material, and lecithin as emulsifier and also antioxidant. In early researches the extracted method was optimized and active principles were determined by HS-SPME-GC-MS. Sequentially, the process conditions of microencapsulation by spray-drying were optimized. The sensory and physical properties were evaluated, and the micro-structure of the microcapsule was observed by scanning electron microscope (SEM) as well. In addition, the delayed release effect was also investigated.The garlic oil extracted by supercritical fluid (SFE) was purified by molecular distillation (MD).Take volatile components of garlic oil, which was analyzed by Headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), as the main indexes, the optimum purification conditions were determined as follows: sampling rate 1 drop/s, distillation temperature 60℃, wiped film speed 250r/min. Non- sulphocompound and oxygenated chemicals wre removed. There were only four volatile components in purification garlic oil: Diallyl disulfide, Diallyl trisulfide, 2-Vinyl-1,3-dithiacyclohex-4-ene, 3-Vinyl-1,2-dithiacyclohex-5-ene. The fresh garlic oil (F-GO) bought from the market was extracted by steam distillation. SFE was a better way to produce garlic oil compared with steam distillation.Taking microencapsulation efficiency as the main evaluating index; and by single-factor experiment, the optimum processing conditions of microencapsulation of garlic oil were determined as follows: homogenizing times, homogenizing time, and homogenizing pressure were once, two minutes, 25MPa respectively. The wall materials were determined as follows: modified starch 20%,β-cyclodextrin 20%, sodium caseinate2%, lecithin 0.75%, and the proportion of garlic oil 20%, inlet and outlet temperature were 180℃and 70℃. Under the optimum conditions, the encapsulation efficiency can achieve 91.08%.The product was pure white. Solubility was 94.32%, water content was 2.55%. In addition, it processed the hydroscopic property and perfect delayed release effect in simulated gastric juice and intestinal juice. By scanning electron microscppe (SEM) ,the micro-structure observation of the microcapsule of garlic oil showed that both the surface and inside structures were good.In this paper, the technology of microencapsulation preparation of garlic oil was systematically researched. Evidently, the microcapsule of garlic oil had good characteristics. Those might be conducive to the development of garlic oil into speciality supplement for human health.