Browsing by Author "Velho, Manuela"
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- Chemical characterization of pine bark (Pinus pinaster Aiton subsp. atlantica), antioxidant properties and phenolic profile of its extractsPublication . Vieito, Catarina; Pires, Preciosa; Fernandes, Élia; Velho, ManuelaIntroduction: Pine bark is an agroindustrial residue from the timber industry and represents a source of phenolic compounds. These compounds have several beneficial properties being antioxidants, antimicrobial, anti-inflammatory, cardiovascular, among others. Objetives: The aim of this work was to study the chemical composition of the bark from Pinus pinaster Aiton subsp. atlantica and the phenolic profile of its aqueous, ethanolic and hydroethanolic extracts. Methods: The moisture content, ash, protein, crude fat and carbohydrates were analysed. The bark was extracted with water, ethanol or a mixture of both in a Soxhlet apparatus and the extraction yield, total phenolic content (TPC), antioxidant activity and phenolic profile by RP-HPLC-UV, in the extracts with higher TPC, were determined. Results: The results obtained for chemical composition were: 63.43 of carbohydrates, 2.81 of crude fat, 1.60 of proteins and 1.75 of ash, calculated in % w/w of dry bark. The extraction yield was greater for the ethanolic and the hydroethanolic extracts (17.08 and 17.55% w/w dry bark, respectively). The TPC and antioxidant activity were higher in the hydroethanolic extract (73.48 mg GAE/g and 108.74 mg AAE/g dry bark, respectively). Regarding the phenolic profile of the hydroethanolic extract, gallic acid, taxifolin, ferulic acid and quercetin were identified at 280 nm, and catechin was identified in the ethanolic extract at 320 nm. Conclusion: P. pinaster Aiton subsp. atlantica bark is mainly constituted by carbohydrates and it is rich in hydroethanolic and ethanolic extractives, being that these have high antioxidant activity. The ethanolic extract presents higher catechin amount when compared to the hydroethanolic extract.
- Hydrocolloids effect on coating batter and on organoleptic properties of rissol regenerated in oven and comparison with deep-frying processPublication . Sousa, Ana; Velho, Manuela; Alves, Manuel; Pinheiro, RitaIntroduction: Consumers' preference for lower fat products continues to increase and there is a significant pressure on industry to reduce the use of frying processes. Objetives: Evaluate the effect of hydrocolloids on the Rissol coating, avoiding the pre-frying or frying processes. It’s also intended to compare physicochemical characteristics of the Rissol obtained, using oven regeneration process and traditional deep-frying, and consumer's acceptability of oven regenerated Rissol. Methods: Hydrocolloids such as carboxymethylcellulose, hydroxypropylmethylcellulose, methylcellulose, xanthan, karaya and locust bean gums, were used alone in the coating system at concentrations of 0.5% and 1.5%(w/w), as well as the synergies established between pairs of gums to a final concentration of 1%(w/w). Rissol was regenerated in the oven (200°C, 18 minutes) and instrumental texture, colour, moisture and organoleptic properties (quantitative descriptive analysis) were measured. The contents in protein, carbohydrates, total fat, fibre, sodium chloride and moisture and consumer’s acceptability in Rissol with 0.5%(w/w) of carboxymethylcellulose were determined, to compare deep-frying and oven cooking processes. Results: The addition of 0.5%(w/w) of any of hydrocolloids studied to the coating system offers better prospects to produce an oven product without pre-frying. The formulations with 1.5%(w/w) of hydrocolloid showed a poorer appearance with cracks and lumps. Conclusion: The use of carboxymethylcellulose in coating batter could be an alternative to obtain a product with reduced total fat and with positive consumer acceptability results (with oven regeneration).