A review of the antioxidant potential of medicinal plant species

Some researchers suggest that two-thirds of the world's plant species have medicinal value; in particular, many medicinal plants have great antioxidant potential. Antioxidants reduce the oxidative stress in cells and are therefore useful in the treatment of many human diseases, including cancer, cardiovascular diseases and inflammatory diseases. This paper reviews the antioxidant potential of extracts from the stems, roots, bark, leaves, fruits and seeds of several important medicinal species. Synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxylanisole (BHA) are currently used as food additives, and many plant species have similar antioxidant potentials as these synthetics. These species include Diospyros abyssinica, Pistacia lentiscus, Geranium sanguineum L., Sargentodoxa cuneata Rehd. Et Wils, Polyalthia cerasoides (Roxb.) Bedd, Crataeva nurvala Buch-Ham., Acacia auriculiformis A. Cunn, Teucrium polium L., Dracocephalum moldavica L., Urtica dioica L., Ficus microcarpa L. fil., Bidens pilosa Linn. Radiata, Leea indica, the Lamiaceae species, Uncaria tomentosa (Willd.) DC, Salvia officinalis L., Momordica Charantia L., Rheum ribes L., and Pelargonium endlicherianum. The literature reveals that these natural antioxidants represent a potentially side effect-free alternative to synthetic antioxidants in the food processing industry and for use in preventive medicine.     

A Critical Review on the Spray Drying of Fruit Extract: Effect of Additives on Physicochemical Properties

Spray drying accomplishes drying while particles are suspended in the air and is one method in the family of suspended particle processing systems, along with fluid-bed drying, flash drying, spray granulation, spray agglomeration, spray reaction, spray cooling, and spray absorption. This drying process is unique because it involves both particle formation and drying. The present paper reviews spray drying of fruit extracts, such as acai, acerola pomace, gac, mango, orange, cactus pear, opuntia stricta fruit, watermelon, and durian, and the effects of additives on physicochemical properties such as antioxidant activity, total carotenoid content, lycopene and β-carotene content, hygroscopy, moisture content, volatile retention, stickiness, color, solubility, glass transition temperature, bulk density, rehydration, caking, appearance under electron microscopy, and X-ray powder diffraction. The literature clearly demonstrates that the effect of additives and encapsulation play a vital role in determining the physicochemical properties of fruit extract powder. The technical difficulties in spray drying of fruit extracts can be overcome by modifying the spray dryer design. It also reveals that spray drying is a novel technology for converting fruit extract into powder form.     

Conversion of microalgae to biofuel

This paper primarily presents an overall review of the use of microalgae as a biofuel feedstock. Among the microalgae that have potential as biofuel feedstock, Chlorella, specifically, was thoroughly discussed because of its ability to adapt both to heterotrophic and phototrophic culture conditions. The lipid content and biomass productivity of microalgae can be up to 80% and 7.3 g/l/d based on the dried weight of biomass, respectively, making microalgae an ideal candidate as a biofuel feedstock. The set-up of the system and the biomass productivity of microalgae cultivated in an open pond and a photobioreactor were also compared in this work. The effect of the culture condition is discussed based on the two-stage culture period. The issues that were discussed include the light condition and the CO₂, DO and N supply. The microalgal productivities under heterotrophic and phototrophic culture conditions were also compared and highlighted in this work. The harvesting process and type of flocculants used to aid the harvesting were highlighted by considering the final yield of biomass. A new idea regarding how to harvest microalgae based on positive and negative charges was also proposed in this work. The extraction methods and solvents discussed were primarily for the conventional and newly invented techniques. Conversion processes such as transesterification and thermochemical processes were discussed, sketched in figures and summarized in tables. The cost–benefit analysis of heterotrophic culture and the cultivation system was highlighted at the end of this work. Other benefits of microalgae are also mentioned in this work to give further support for the use of microalgae as a feedstock for biofuel production.     

Microencapsulation of Morinda citrifolia L. extract by spray-drying

Microcapsules containing Morinda citrifolia L. microparticles were produced by a spray-drying technique using various proportions of κ-carrageenan and maltodextrin as the binding materials. In this work, the effects of spray-drying on the encapsulation yield, particle size, moisture content, DPPH scavenging activity, total phenolic content and total flavonoid content of the bioactive components of M. citrifolia L. were determined for different volume ratios in the inlet air temperature range of 90–140 °C. The results showed that the percentage of 2,2-diphenyl picrylhydrazyl (DPPH) scavenging activity of the spray-dried powder was the highest for the 1:2 ratio (volume ratio of M. citrifolia L. extract to additive solution) at 90 °C, with maltodextrin at a concentration of 33 mg/ml. The results also showed that the microcapsules had a regular spherical shape. The spray-dried M. citrifolia fruit extract showed high antioxidant activity (28.36% DPPH activity), thus suggesting that it might be useful as a food additive and/or ingredient under the above optimum operating conditions.     

Effect of ultrasound on liquid phase adsorption of azeotropic and non-azeotropic mixture

Relative adsorption experiments of azeotropic and non-azeotropic mixture were separately conducted at constant temperature with and without the presence of ultrasound. The ultrasound wave was applied at a frequency of 21 kHz with 25% amplitude at atmospheric pressure. The adsorption of azeotropic and non-azeotropic mixture was analysed using monolayer adsorption theory and at lower liquid equilibrium concentration it followed a Langmuir type of equation. The adsorptive capacity of azeotropic and non-azeotropic mixtures on activated carbon was found to decrease but the selectivity was increased. The result also showed that the azeotropic point of relative adsorption was noticeably moved due to the ultrasound effect.