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35 results on '"Giovanelli, Gabriella"'

6. Application of Ultrasonic Intensification Technology in the Extraction of Bio-Actives from Spent Coffee Grounds and Spent Tea Leaves.

Author

Girotto, Francesca, Piazza, Laura, Ratti, Simona, and Giovanelli, Gabriella

Subjects
COFFEE grounds, FUNCTIONAL foods, BEVERAGES, ANTIOXIDANTS, CAFFEINE
Abstract

Spent coffee grounds (SCG) and spent tea leaves (STL) are leftovers of the two most diffused beverages all over the world, coffee and tea. Functional components commonly found within raw materials, i.e. caffeine and phenolic compounds such as chlorogenic acid, gallic acid, and catechin derivatives, are not fully extracted from coffee grounds and tea leaves during beverage preparation. Therefore, SCG and STL can be regarded as a source of bioactives to be valorised in the formulation of various functional foods and beverages. In the present study, ultrasound-assisted extraction (UAE) and conventional solvent extraction aimed at the recovery of natural antioxidants and caffeine from SCG and STL were compared. In particular, ethanol 60% (v/v) and boiling water were used as solvent media and the effects of two different ultrasound (US) waves amplitudes (80 and 152 μm) and treatment time (5 and 10 min) were investigated. This study closes a literature gap on UAE from SCG and STL using GRAS (Generally Recognized as Safe) solvents, in particular with water. US had an evident positive effect on the recovery of natural antioxidants when the solvent media was aqueous ethanol. In particular, applying the US treatment at 152 μm for 10 min, the total phenolic compounds content of SCG (24.01 ±0.01 mgGAE/gTS) and STL (243.67 ±12.36 mgGAE/gTS) extracts doubled and quadrupled, respectively. Likewise, caffeine recovery significantly increased after sonication up to 2.19 ±0.02 mg/gTS from SCG and up to 12.74 ±0.36 mg/gTS from STL. [ABSTRACT FROM AUTHOR]

Published
2023
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34. Apple Juice Stabilization by Combined Enzyme—Membrane Filtration Process

Author

Giovanelli, Gabriella and Ravasini, Giorgio

Abstract

Stabilization against discolouration and clouding is a major problem in fruit juice production. Effects of enzymatic oxidation of polyphenols, associated with 'active filtration' and membrane filtration were evaluated, in terms of juice characteristics and stability. Laccase oxidation produces a significant decrease in the phenolic content of juices, associated with a remarkable colour increase. Active filtration by polyvinylpolypyrrolidone and activated charcoal partially decolourates the oxidized juices and stabilizes these products, removing a high quantity of phenolic compounds. Membrane filtration demonstrates to be an effective technique in terms of stabilization only if performed using low molecular weight cut-off membranes. Copyright 1993, 1999 Academic Press

Published
1993
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35. A low-cost and low-tech electrochemical flow system for the evaluation of total phenolic content and antioxidant power of tea infusions

Author

Buratti, Susanna, Scampicchio, Matteo, Giovanelli, Gabriella, and Mannino, Saverio

Subjects
*ORGANIC acids, *PHENOLIC acids, *ANTIOXIDANTS, *TEA
Abstract

Abstract: A disposable, small scale and low-cost electrochemical “wall-jet” flow-cell was build up together with a graphite lead mounted onto a pencil holder able to modulate the current response by the control of the surface area of the electrode. The total phenolic content of different types of tea infusions was determined and compared with the conventional Folin–Ciocolteau method. An index of antioxidant power was also proposed and data were compared with those obtained by the DPPH* assay. [Copyright &y& Elsevier]

Published
2008
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