Antioxidant pectins from eggplant (Solanum melongena) fruit exocarp, calyx and flesh isolated through high-power ultrasound and sodium carbonate.

Dried and milled eggplant fruit peel and calyces (PC) and mesocarp, placenta and core (Mes) were utilized as natural sources of valuable chemicals. Pectins were extracted with 0.1 M Na2CO3 (1 h; 23 °C). A high-power ultrasound (US) pretreatment (10 min net time; 12.76 W/cm2 power intensity) in 10:200 (g/mL) powder:water ratio led to the lowest solvent and energy consumptions after the subsequent 0.1 M Na2CO3 stirring, permitting the highest recoveries of uronic acid (UA) from PC and Mes (80.25 and 93.8 %, respectively). Homogalacturonans (>65 % w/w UA) of low degree of methylesterification, of acetylation, and 90,214-138,184 Da molecular weights with low polydispersity (≈1.32-1.40) were obtained. They included released ferulate (≈3.5 mg/100 g) esterified pectins. Antioxidants (caffeoylquinic acid, putrescine and spermidine derivatives, ß-carotene, lutein) gave additional technological value to their thickening effect as pectins protected tryptophan, tyrosine, alkyl side chains and sulfhydryl of skim milk proteins from UV-C photo-oxidation.

Modification of the content of n-3 highly unsaturated fatty acid, chemical composition, and lipid nutritional indices in the meat of grass carp (Ctenopharyngodon idella) fed alfalfa (Medicago sativa) pellets.

A 120-d feeding trial was conducted to determine the effect of alfalfa (Medicago sativa) feeding on growth and chemical composition, fatty acid content, and nutritional and lipid indices of the meat of grass carp (Ctenopharyngodon idella). Two experimental diets were used: alfalfa pellet (AP) diet and artificial grain diet (GD). Final weight, feed conversion rate, and protein efficiency ratio were significantly greater in the GD group (P < 0.05). However, no differences in the length and condition factor were observed. The composition of the meat differed between treatments. The protein content was significantly greater in the AP group (P < 0.05), while the lipid and cholesterol contents were significantly greater in the GD group (P < 0.05). A greater proportion of saturated, n-6 polyunsaturated, and n-6 highly unsaturated fatty acids was obtained in the GD group. The AP group accumulated a greater concentration of eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic (DHA) acids (P < 0.05). The fatty acid composition of the meat determined a significant decrease in the thrombogenicity index and saturation index (S/P) in the AP group (P < 0.05). The Elongase index was greater in the GD group (P < 0.05). In contrast, the AP group had a greater index of Δ9 Desaturase and Δ5 + Δ6 Desaturase for n-3 and n-6 fatty acids (P < 0.05). These results suggest that alfalfa feeding decreases the growth of C. idella but improves the quality of meat by increasing the protein, EPA, and DHA contents. It also reduces cholesterol content and improves nutritional indices.

Antioxidant pectin enriched fractions obtained from discarded carrots (Daucus carota L.) by ultrasound-enzyme assisted extraction.

Carrot residues were upgraded as pectin-enriched fractions (PEFs) useful for functional food formulation due to co-extracted antioxidants (α- and ß-carotenes, lutein, α-tocopherol), and gelling effect. High power ultrasound (US)-enzyme assisted extraction was applied for efficiency and sustainability. Carrot powder (CP) in citrate-buffer (pH 5.20) was submitted to US-pretreatment (12.27 W/cm2: 20 kHz, 80% amplitude, 20 min) and a subsequent digestion (5 h-40 °C) without or with hemicellulase or cellulase. US-hemicellulase led to the highest PEF yield (27.1%), and extracted almost the whole pectin content of CP. US-pretreatment increased the extraction yield of all PEFs, but the existence of an additional positive effect of the following step depended on the enzyme used. PEFs contained 40-47% of UA with low DM (24-49.9%), and co-extracted antioxidants. US decreased the antioxidant contents, DM, and molecular weight, but allowed obtaining calcium crosslinked true gels, also with higher elastic modulus than non-US-extracted PEFs, being promising as food additives.

Pectin-based composite film: Effect of corn husk fiber concentration on their properties.

Considering the polysaccharide composition and 32% of crystallinity of the water insoluble fiber extracted from corn husk (CHF) agricultural residue, its filler performance as water vapor permeability (WVP) and mechanical modifier in edible films based on commercial low methoxyl pectin (LMP) was evaluated (0, 1, 3, 5, 8% concentrations). The 53-µm-CHF carried phenolics and carotenes, and composites showed antioxidant capacity. Homogeneous films with a continuous LMP matrix were obtained. The 5%-CHF composite showed the highest surface contact angle (44°) and tensile strength, without change in elongation, while WVP was decreased in the 3-8% CHF-LMP-films. The latter was ascribed to the CHF-filler crystallinity whereas the improvement in mechanical performance and contact angle was attributed to a CHF-interconnected network formed at 5%-CHF critical concentration. Corn husk residue can be utilized as a source of fibers for material development. Composites with enhanced performance can be an antioxidant strategy at food interfaces.

Hydrolytic and oxidative stability of L-(+)-ascorbic acid supported in pectin films: influence of the macromolecular structure and calcium presence.

The hydrolytic and oxidative stability of L-(+)-ascorbic acid (AA) into plasticized pectin films were separately studied in view of preserving vitamin C activity and/or to achieve localized antioxidant activity at pharmaceutical and food interfaces. Films were made with each one of the enzymatically tailored pectins (50%, 70%, and 80% DM; Cameron et al. Carbohydr. Polym.2008, 71, 287-299) or commercial high methoxyl pectin (HMP; 72% DM). Since AA stability was dependent on water availability in the network, pectin nanostructure affected the AA kinetics. Higher AA retention and lower browning rates were achieved in HMP films, and calcium presence in them stabilized AA because of higher water immobilization. Air storage did not change AA decay and browning rates in HMP films, but they significantly increased in Ca-HMP films. It was concluded that the ability of the polymeric network to immobilize water seems to be the main factor to consider in order to succeed in retaining AA into film materials.

Development of a high methoxyl pectin edible film for retention of l-(+)-ascorbic acid.

An edible film to carry l-(+)-ascorbic acid (AA) was formulated for natural antioxidant food protection. Considering previous works where films based on the "rigid" structure of gellan (deacylated) or on a mixture of acylated-deacylated (more "disordered") gellan were used for network development, pectin was herein chosen by considering that the alternating presence of "disordered" (hairy) regions together with ordered (homogalacturonan) ones could sufficiently immobilize water for better AA retention and lower browning. High methoxyl pectin (HMP) was first investigated. AA stability and browning were studied during film storage at 33.3, 57.7, or 75.2% relative humidity (RH) and 25 degrees C; their dependence on water mobility determined through (1)H NMR analysis as well as the correlation between browning and AA degradation were again found. Network characteristics and glycerol (plasticizer) interactions were analyzed through X-ray diffraction and Fourier transform infrared spectroscopy as well as through uniaxial tensile assay. From all results obtained, it was hypothesized that browning development in solidlike systems may be directly related to the water molecules more closely adsorbed on the hydroxyl-polymeric (active) surfaces. The HMP film microstructure produced the best immobilization of water molecules except at 75.2% RH, where it showed lower AA stability than acylated-deacylated gellan film. It is suggested that disordered regions of this pectin network may not be adequately counterbalanced by more transient junction zones of alternating hydrophilic (water) and hydrophobic (methyl ester) interactions, also disturbed by glycerol molecules, for accomplishing enough water immobilization in the whole network at 75.2% RH.