After processing, every extraction process generates huge amount of unintended wastes, especially from fruits and vegetables which represent a major disposal problem for the food industry. They are promising sources of bioactive compounds that could be used for their favourable nutritional properties. Sea buckthorn juice production results in generation of large amount of by-products, which are suggested to contain substantial amounts of valuable natural antioxidants. Extracts obtained by solvent-free microwave hydrodiffusion and gravity (MHG) technique and conventional solvent extraction (CSE) method were analysed with HPLC for quantification of flavonoids along with evaluating their phenolic contents by Folin-Ciocalteu method and reducing power by the reduction of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. MHG is a green extraction method which offers important advantages like shorter extraction time (15 min), cleaner feature (no solvent or water used) and extraction of valuable flavonoids (Isorhamnetin, isorhamnetin 3-O-glucoside, isorhamnetin 3-O-rutinoside and quercetin 3-O-glucoside) at optimised power (400 W). Along with extracting similar flavonols in enough concentratioin, MHG extract has shown much higher phenolic contents (1,147 milligram gallic acid equivalents (GAE) per gram) against CSE extract (741 mg GAE/g) with greater antioxidant activity determined by DPPH assay.

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Vegetal extracts are widely used as primary ingredients for various products from creams to perfumes in the pharmaceutical, nutraceutic and cosmetic industries. Having concentrated and active extract is essential, as the process must extract as much soluble material as possible in a minimum time, using the least possible volume of solvent. The boldo leaves extract is of great interest for the industry as it holds a great anti-oxidant activity due to high levels of flavonoids and alkaloids such as boldine. Ultrasound Assisted Extraction (UAE) has been used to improve the efficiency of the plant extraction, reducing extraction time, increasing the concentration of the extract with the same amount of solvent and plant material. After a preliminary study, a response surface method has been used to optimize the extraction of soluble material from the plant. The results provided by the statistical analysis revealed that the optimized conditions were: sonication power 23 W/cm2 for 40 min and a temperature of 36 °C. The optimized parameters of the UAE provide a better extraction compared to a conventional maceration in terms of process time (30 min instead of 120 min), higher yield, more energy saving, cleanliness, safety and product quality.

The grape juice by-product obtained from grape traditional press was extracted by Microwave Hydrodiffusion and Gravity (MHG); a green extraction technique preliminarily optimized at 1 W/g. The MHG extract (MHGE) was analyzed by HPLC for identification and quantification of anthocyanins and other phenolic compounds. Then, MHGE was added to the natural juice (NJ) to produce an innovative grape juice (IJ). These three juices were evaluated for their total polyphenol content (TPC), total anthocyanin content (TAC) in addition to their sensorial characteristics. MHGE showed the highest values of TPC (21.41±0.04 mg GAE/g DW), TAC (4.49±0.01 μg MVGE/g DW). Moreover, IJ (grape juice enriched with MHGE) was richer in TPC (6.70±0.0 1mg GAE/g DW) and TAC (3.96±0.01 μg MVGE/g DW) than NJ (2.90±0.02 mg GAE/g DW and 3.63±0.06 μg MVGE/g DW, respectively).

Sea buckthorn (SBT) pomace, a by-product of juice production, has been studied as a potential carotenoids source because such compounds are of great interest in the food industry. Ultrasoundassisted extraction (UAE) has been used to improve the direct enrichment of edible oils (sunflower, rape seed, olive, and soya) with SBT carotenoids. These oils do not naturally contain carotenoids. After a preliminary study, a RSM has been used to maximize total carotenoid content of extracts and the influence of process variables on the UAE has been investigated. The results provided by the statistical analysis revealed that the optimized conditions were: sonication power of 0.67 W/g oil and a temperature of 358C. The optimization parameters of this ''green'' process provide a greatly improved enrichment of the edible oil in terms of quantity and process time from 33.83 mg/L extract in 90 min obtained by conventional extraction to 51.64 mg/L extract in only 20 min by UAE. Ultrasound-assisted carotenoids extraction from SBT by-products appears to be a simple, rapid, and sustainable alternative to conventional procedures.Practical applications: Improving the value of low quality edibles is important for the food, cosmetic, or nutraceutical industry. It is done by adding ingredients such as carotenoids which are extracted by hexane or other solvents. In this study we show an innovative application of a direct extraction by maceration of by-products in edible oil without solvent and eliminating evaporation and extraction unit operations. Using ultrasound, full extractions can now be completed in minutes with high reproducibility, reducing the consumption of solvent, simplifying manipulation and work-up, giving higher purity of the final product, eliminating post-treatment of waste water, and consuming only a fraction of the fossil energy normally needed for a conventional extraction method such as Soxhlet extraction, maceration, or steam distillation.