Jorge Sineiro

Natural antioxidants from residual sources

The growing interest in the substitution of synthetic food antioxidants by natural ones has fostered research on vegetable sources and the screening of raw materials for identifying new antioxidants. Oxidation reactions are not an exclusive concern for the food industry, and antioxidants are widely needed to prevent deterioration of other oxidisable goods, such as cosmetics, pharmaceuticals and plastics. Polyphenols are the major plant compounds with antioxidant activity, although they are not the only ones. In addition, other biological properties such as anticarcinogenicity, antimutagenicity, antiallergenicity and antiaging activity have been reported for natural and synthetic antioxidants. Special attention is focussed on their extraction from inexpensive or residual sources from agricultural industries. The aim of this review, after presenting general aspects about natural antioxidants, is to focus on the extraction of antioxidant compounds (mainly polyphenols) from agricultural and industrial wastes, as well as to summarize available data on the factors affecting their antioxidant activity and stability, and, in some cases, the reported major active compounds identified.

Influence of natural extracts on the shelf life of modified atmosphere-packaged pork patties

In this study four natural extracts from tea (TEA), grape (GRA), chestnut (CHE) and seaweed (SEA) with potential antioxidant activity were evaluated in pork patties. During 20 days of storage in modified atmosphere packs at 2°C, pH, colour, lipid oxidation and microbial spoilage parameters of raw minced porcine patties were examined and compared with a synthetic antioxidant (BHT) and control (CON) batch. Due to their higher polyphenol content, GRA and TEA extracts were the most effective antioxidants against lipid oxidation, also limiting colour deterioration. In addition, both natural extracts led to a decrease of total viable counts (TVC), lactic acid bacteria (LAB), Pseudomonas and psychotropic aerobic bacteria compared to the control. Among the four natural compounds tested, tea and grape extracts showed the most potential as alternatives to commercial antioxidants, for increasing the quality and extending the shelf-life of porcine patties.

Extracts of Maqui (Aristotelia chilensis) and Murta (Ugni molinae Turcz.): Sources of Antioxidant Compounds and α-Glucosidase/α-Amylase Inhibitors

The objective of this work was to evaluate the antioxidant and antihemolytic activities of crude, aqueous, and organic-aqueous extracts of maqui ( Aristotelia chilensis ) and murta ( Ugni molinae Turcz.), together with their inhibiting effect on enzymes involved in the metabolism of carbohydrates. Radical scavenging activity, inhibition of linoleic acid oxidation in a micellar system, antihemolytic activity, and inhibition of α-amylases and α-glucosidases were analyzed. Crude extracts of maqui leaves and fruits were found to be important sources of polyphenolic compounds, showing 69.0 ± 0.9 and 45.7 ± 1.1 mg GAE/g dm, respectively. Polyphenols from maqui leaves were active as antioxidants and antihemolytic compounds (p < 0.05), showing a noncompetitive inhibiting effect on α-glucosidase. Flavan-3-ol polymers and glycosylated flavonols, such as quercetin glucoside and kaempferol glucoside, were tentatively identified in extracts. This preliminary observation provides the basis for further examination of the suitability of polyphenol-enriched extracts from maqui and murta as nutritional or medicinal supplements with potential human health benefits.

Antiradical Activity, Phenolics Profile, and Hydroxymethylfurfural in Espresso Coffee: Influence of Technological Factors

The influence of technological factors (decaffeination, brew volume, coffee species, and roast degree) on antiradical activity and phenolics content of espresso coffee is described. The screenings of phenolics profile and other compounds (caffeine and trigonelline), as well as the quantification of hydroxymethylfurfural, were performed by LC-DAD-ESI-MS. Significantly lower (p < 0.05) scavenging activities and phenolics contents were found in decaffeinated espressos when compared with regular ones (32 vs 38% and 324 vs 410 mg/30 mL cup, respectively). A long espresso (70 mL) offers more than twice the phenolics amount of a short one (20 mL). Robusta brews showed higher (p < 0.05) antiradical activity and phenolic contents than arabica ones, for all roast degrees (light, medium, and dark). No significant differences (p > 0.05) were observed for scavenging activities of differently roasted robusta brews, whereas an increase in medium-dark brews was observed for arabica samples. Total phenolics in robusta espressos decreased (p < 0.05) with the increase of roast degree, but no significant differences (p > 0.05) were found between arabica espressos from different roasts. By LC-DAD-ESI-MS, 23 hydroxycinnamic derivatives were found, including chlorogenic acids, lactones, and cinnamoyl-amino acid conjugates. The amount of each compound was differently affected by species and roast. Robusta brews presented superior levels of caffeine and chlorogenic acids, whereas arabica ones contained more trigonelline. Hydroxymethylfurfural contents in the brew (30 mL) varied from 2.60 to 0.84 mg for light- and dark-roasted arabicas and from 1.29 to 0.68 mg for light- and dark-roasted robustas, respectively.

Antioxidant activity of extracts from Gevuina avellana and Rosa rubiginosa defatted seeds

Abstract Chilean hazelnuts (Gevuina avellana Mol) and mosqueta rose (Rosa aff. Rubiginosa L.) meals were extracted with methanol, ethanol, acidified water, acetone, butanol, diethyl ether and ethyl acetate. Ethanol and methanol extracted the highest amount of soluble substances from both seed meals. The highest concentration of total polyphenols was found in the ethanolic extracts, although that of acetone from R. rubiginosa presented similar values. The antioxidant activity of the extracts evaluated by the β-carotene assay and with as hydrogen radical scavenging ability showed that the activity of the butanol and methanol extracts from G. avellana was comparable to those of synthetic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The 2,2,-diphenyl-1-picrylhydrazyl radical (DPPH) radical scavenging activity of the G. avellana methanol, ethanol and water extracts was 2–3 times lower than those of BHT and BHA, respectively. The activity of R. rubiginosa extracts ranged from that of BHT for the water extracts to 80% inhibition in respect to control achieved with the ethanol extracts.

FLAXSEED AS A SOURCE OF FUNCTIONAL INGREDIENTS

Scientific evidence supports flaxseed consumption; however, a large sector of the population is still unaware of the benefits associated to its consumption and its possible applications as functional food ingredient in foodstuffs. Flaxseed is mainly known by its high alpha-linolenic acid content, but it is also a lignan source, soluble fibre and protein, compounds which are biologically active in the prevention of some non-transmissible chronic diseases. Southern Chile has comparative advantages for the cultivation of this crop. Together with its full processing, this crop could strengthen regional industry. The purpose of the present review is to highlight the nutritional properties of flaxseed.

On the double role of surfactants as microalga cell lysis agents and antioxidants extractants

An integrated process based on the concomitant role of non-ionic surfactants as cell disrupters and organic extractants of intracellular antioxidants is proposed for the first time in this work. The lytic effect of two common families of surfactants on the cell walls of the microalga Tetraselmis suecica has been initially evaluated. The antioxidant extraction based on aqueous two-phase systems (ATPS) was proposed using different potential salting out agents such as sodium inorganic and organic salts in aqueous solutions of the selected surfactants. The extraction efficiency was ascertained for the most representative biomolecules previously detected in this microalga: α-tocopherol, β-carotene and gallic acid. The viability of the process was checked in real lyophilized microalga samples, yielding higher antioxidant activity than that provided by an ultrasound-based conventional method.

Enzymatic treatment of sunflower kernels before oil extraction

Sunflower kernels were enzymatically treated before pressing, with the aim of enhancing oil extractability. Following the response surface methodology, the combined effects of moisture, enzyme/kernel ratio and treatment time were examined. The effect of these variables on the pressing efficiency, the protein digestibility, the fiber content and the meal color was assessed. In a wide range of conditions, it was found that the pressing efficiency was higher for treated kernels, obtaining 13% additional oil compared with untreated samples. Also, the in vitro apparent digestibility coefficient of the meal was improved and the total fiber content was reduced. A slight darkening of the meal was observed as a result of the operational conditions during the treatment. The solvent extractability of the enzymatically treated pressed cakes was enhanced compared with that of the untreated sample.

FLAXSEED AND FLAXSEED CAKE AS A SOURCE OF COMPOUNDS FOR FOOD INDUSTRY

Flax (Linum usitatissimum) has been used for centuries as a source for oil extraction. In recent years it has attracted considerable interest as a result of studies which attribute potential health benefits to its components, including the prevention of chronic non-communicable diseases. Among these compounds presenting biological activity, alpha-linolenic acid, lignans and soluble fibre are of special interest. Southern Chile has comparative advantages for the cultivation of this crop. Together with its full processing, this crop could strengthen regional industry. The purpose of the present work is to learn how the best use can be made of these compounds, by studying flaxseed and flaxseed cake as sources of compounds of interest for food industry. Oil extracted from flaxseed contained 51.86% of linolenic, 16.34% of linoleic and 20.98% of oleic acid. Fractioning of defatted flaxseed cake produced a polyphenol content of 0.73 mg GAEg-1 extract and a protein isolate of considerable purity, 53.15% yield with 0.78 gof albumin equivalent g-1 protein isolate. Additionally, a polysaccharide was isolated with low protein content as impurity, 10.71% yield with 1.37 mg of glucose equivalent per gram of polysaccharide. This information will form the basis for assessing the extraction of products of interest for the food industry from flaxseed cake.

Recovery and Concentration of Antioxidants from Winery Wastes

: Grape and wine byproducts have been extensively studied for the recovery of phenolic compounds with antioxidant activity and a variety of biological actions. The selective recovery and concentration of the phenolic compounds from the liquid phase separated from further diluted winery wastes has been proposed. Adsorption onto non ionic polymeric resins and further desorption with ethanolic solutions was studied. Several commercial food grade resins were screened with the aim of selecting the most suited for the practical recovery of phenolic compounds with radical scavenging activity. Under the optimized desorption conditions (using Sepabeads SP207 or Diaion HP20 as adsorbents and eluting with 96% ethanol at 50 °C) a powdered yellow-light brown product with 50% phenolic content, expressed as gallic acid equivalents, was obtained. The radical scavenging capacity of one gram of product was equivalent to 2–3 g of Trolox.