Pretreatment of citrus by-products affects polyphenol recovery: a review

Abstract

A large amount of citrus waste is generated annually. This waste is of great economic worth, since it contains high levels of polyphenols, which have attracted scientific interest due to their potent antimicrobial and antiradical activities. Pre-treatment is a crucial step that precedes the extraction process and influences the yields and quality of polyphenols. This review emphasizes the effect of different drying processes, such as freeze drying, hot-air drying, vacuum drying, infrared drying, and high-speed drying, on the polyphenol retention in citrus by-products. Further treatments of the dried citrus by-products for assisting the liberation of bound polyphenols are also provided and comprehensively discussed.

Encapsulation of Citrus By-Product Extracts by Spray-Drying and Freeze-Drying Using Combinations of Maltodextrin with Soybean Protein and ι-Carrageenan

“…During the grinding of the lyophilized material, the surface exposed to oxygen increased, leading to the oxidation of the phenolic compounds and antioxidants. In case of spray-drying, the lower polyphenol and antioxidant capacity values could be attributed to the polyphenol degradation/conversion due to the high inlet temperatures generated during the process [ 1 , 12 , 31 ]. The TPC and FRAP values of the powders obtained by freeze-drying ranged from 1.30 to 1.66 mg GAE/g d.b., and from 3.36 to 3.70 mM TE/g, respectively.…”

“…Huge amounts of citrus by-products are generated annually by the juice industry [ 1 ]. These residues are a significant potential source of polyphenols, which possess radical scavenging properties towards oxygen species, and complexing properties towards proteins [ 2 ].…”

“…These residues are a significant potential source of polyphenols, which possess radical scavenging properties towards oxygen species, and complexing properties towards proteins [ 2 ]. Due to the presence of unsaturated bonds in their molecular structure, polyphenols are susceptible to light, heat, and oxygen degradation [ 1 , 3 ]. Therefore, extracts enriched in polyphenols should be treated appropriately in order to produce a product that is able to maintain its integrity.…”

Antimicrobial and Antibiofilm Activities of Citrus Water-Extracts Obtained by Microwave-Assisted and Conventional Methods

“…Reports on the phytochemical analyses of these extracts have shown the presence of flavonoids, saponins, tannins, alkaloids, and terpenoids [ 13 ]. During the last decade, the extraction of citrus by-products from dried peels/pomace with hot water has increasingly taken hold to allow improved recovery (mostly polyphenols and phenolics) and reduce the extraction time [ 19 , 30 , 31 , 32 , 33 ]. Accordingly, we compared herein the antimicrobial and antibiofilm activity of hot water extracts obtained from three different citrus peels.…”

Aspectos físico-químicos, nutricionais e sensoriais da adição de subprodutos de frutos do gênero Citrus em produtos de gelificação: uma revisão sistemática

“…Dentre eles, está a redução da atividade de enzimas responsáveis pela degradação de polifenóis como, por exemplo, a polifenol oxidase(Delele et al, 2015;Salazar et al, 2018); a eliminação de agentes patogênicos; a redução de custos com armazenamento e transporte(Papoutsis et al, 2018), já que o volume das embalagens é menor. O processo de desidratação também proporciona que o alimento seja utilizado em períodos de entre safra, aumentando a vida de prateleira(Benseddik et al, 2018), e concentra o conteúdo de nutrientes.…”