Dispersion-assisted extraction of guarana processing wastes on the obtaining of polyphenols and alkaloids

This is the first work to evaluate the effects of high shear mixing (HSM) on the recovery of valuable polar compounds from guarana processing wastes (peels and depleted seeds), which results may server to support researches on the valorization of guarana. Under the optimum condition, the HSM was led to extract catechin (11.11-42.93 g/100 g raw material), epicatechin (7.83-24.78 g/100 g raw material) and caffeine (9.99-28.80 g/100 g raw material) from guarana products, which contents were comparable with those obtained with ultrasound assisted extraction and maceration, and significantly higher than those obtained with infusion and decoction. Besides the relatively low reducing sugar content (0.02-0.23 g glucose equivalent/100 g raw material), HSM extracts also presented high antioxidant capacity (25-533 mg ascorbic acid equivalent/g raw material) and phenolic compounds (0.5-45 g catechin equivalent/100 g raw material and 0.1-66.38 g gallic acid equivalent/100 g raw material). The use of pectinase enhanced the HSM to recover target compounds in depleted seeds. Practical applications The use of guarana has emerged as a source of antioxidants, associated to enhancement of cognitive function, to prevent cancer-related symptoms, and to control the weight. This paper is the first research to use high-shear mixing (HSM) to maximize the recovery of bioactive compounds from the peels and depleted seeds of guarana, the wastes derived from the Brazilian carbonated beverage industry. The extraction efficiency of HSM for 1 min to recover polyphenols and alkaloids was like those of ultrasound assisted assisted and maceration, performed for 30 min. Our results confirm that HSM is an environmentally friendly, rapid and low-cost method to extract bioactive compounds from guarana. Our results are expected to support further researches on the use of HSM as an extraction protocol for analysis and to evaluate the multipurpose potential of guarana processing wastes for food and non-food formulations.