Antioxidant Activity In Emulsions Research Articles

Stabilisation of extra virgin olive oil‐in‐water emulsions prepared by citrus pectin using green tea and grape seed phenolic extracts and catechin

SummaryThis study aimed at the solution of stability problems of extra virgin olive oil rich (oil:aqueous phase ratio = 50:50) model oil‐in‐water emulsions prepared with pectin using green tea (GTE) and grape seed extracts (GSE), and (+)‐catechin (CAT). Olive oil‐in‐water emulsion prepared with pectin at 0.5% (w/v) without phenolics lost 36% of its stability within 1 day. GTE at 1% (w/v) caused a limited increase in emulsion stability while emulsions with GSE at ≥0.25% or CAT at 1% maintained >90% of their stability after 14 days. GSE and CAT reduced the emulsion droplet size (2.6‐ and 1.9‐fold) while GTE increased the emulsion droplet size (1.5‐fold). Emulsions with GSE showed the smallest and most densely packed lipid droplets. The highest phenolic content and antioxidant activity in emulsions were obtained with CAT followed by GSE and GTE. This work is significant in that it showed the possibility of using GSE to obtain stable extra virgin olive oil emulsion‐based functional foods.

Technological, nutritional, and biological properties of apricot kernel protein hydrolyzates affected by various commercial proteases.

The effect of enzymatic hydrolysis of apricot kernel protein with different proteases (Alcalase, pancreatin, pepsin, and trypsin) on the amino acid content, degree of hydrolysis (DH), antioxidant, and antibacterial characteristics of the resulting hydrolyzates was investigated in this study. The composition of amino acids (hydrophobic: ~35%; antioxidant: ~13%), EAA/TAA ratio (~34%), and PER index (~1.85) indicates the ability of the hydrolyzate as a source of nutrients and antioxidants with high digestibility. Enzymatic hydrolysis with increasing DH (from 3.1 to a maximum of 37.9%) led to improved solubility (especially in the isoelectric range) and changes in water- and oil-holding capacity. The highest free radical scavenging activity of DPPH (83.3%), ABTS (88.1%), TEAC (2.38 mM), OH (72.5%), NO (65.7%), antioxidant activity in emulsion and formation of TBARS (0.36 mg MDA/L), total antioxidant (1.61), reducing power (1.17), chelation of iron (87.7%), copper (34.8%) ions, and inhibition of the growth of Escherichia coli (16.3 mm) and Bacillus cereus (15.4 mm) were affected by the type of enzymes (especially Alcalase). This research showed that apricot kernel hydrolyzate could serve as a nutrient source, emulsifier, stabilizer, antioxidant, and natural antibacterial agent in functional food formulations.

Innovative Skin Product O/W Emulsions Containing Lignin, Multiwall Carbon Nanotubes and Graphene Oxide Nanoadditives with Enhanced Sun Protection Factor and UV Stability Properties

In the present study, oil-in-water (O/W) sunscreen emulsions were prepared containing different portions of lignin (LGN), multiwall carbon nanotubes (MWCNTs) and graphene oxide (GO) nanoadditives. The stability in terms of pH and viscosity of emulsions was thoroughly studied for up to 90 days, exhibiting high stability for all produced O/W emulsions. The antioxidant activity of emulsions was also analyzed, presenting excellent antioxidant properties for the emulsion that contains LGN due to its phenolic compounds. Moreover, the emulsions were evaluated for their ultraviolet (UV) radiation protection ability in terms of sun protection factor (SPF) and UV stability. SPF values varied between 6.48 and 21.24 while the emulsion containing 2% w/v MWCNTs showed the highest SPF index and all samples demonstrated great UV stability. This work hopefully aims to contributing to the research of more organic additives for cosmetic application with various purposes.

Differences in antioxidant activity between two rice protein concentrates in an oil‐in‐water emulsion

Two formulations of rice protein concentrates (RPC) derived from brown rice were evaluated for their antioxidant activity in bulk oil and in oil‐in‐water emulsions. Bulk oils were mixed with RPC and heated to 180°C, and total polar compounds and triacylglycerol polymerization were measured. Minimal antioxidant activity was observed in the bulk oil phase. Rice protein concentrates were incorporated into soybean oil‐in‐water emulsions, which were oxidized at 50°C for 8 days. Lipid oxidation in emulsions was assessed via peroxide values (PV), headspace oxygen levels, headspace volatile oxidation products, and fatty acid analysis. One of the RPC treatments showed some antioxidant activity in emulsions, suggesting that RPC could potentially be used to extend shelf life and preserve product quality.Practical applications: Naturally derived antioxidants that can inhibit oxidation in edible oils are in high demand. As consumers become more label‐conscious, synthetic antioxidants are falling out of favor. Rice proteins offer a means of antioxidant capability in emulsions, which may have applications in improving shelf life and/or product quality in a variety of foods, including sauces, salad dressings, and dairy products. Rice protein concentrations show more promise in emulsions than in bulk oil.Protein concentrates derived from brown rice (left) were incorporated into oil‐in‐water emulsions (center) and showed differing abilities to suppress lipid oxidation (linolenic acid, shown right).

Stabilization of Emulsion and Butter like Products Containing Essential Fatty Acids Using Kalonji Seeds Extract and Curcuminoids

Owing to the tendency of essential fatty acids (EFAs) to undergo autoxidation, their storage becomes a key problem. Generally, they are stabilized by synthetic antioxidants like TBHQ that are toxic in nature. Recently many studies were reported where these EFAs are stabilized by natural antioxidants. In the present study, curcuminoids and kalonji seeds ethanol extract (KEE) were used to stabilize these EFAs in refined sunflower oil (RSFO), water-in-oil (w/o) emulsion and butter like products (BLPs). In RSFO, though curcuminoids alone exerted pro-oxidant effect, KEE and curcuminoids showed synergistic antioxidant activity that was comparable to TBHQ. KEE exhibited good antioxidant activity in emulsions and BLPs, providing fine physical properties like slipping point, dropping point and spreadability. EFAs increased the nutritional value of BLPs and antioxidants added for their stabilization provided their medicinal benefits.

Surface-Active Properties of Lipophilic Antioxidants Tyrosol and Hydroxytyrosol Fatty Acid Esters: A Potential Explanation for the Nonlinear Hypothesis of the Antioxidant Activity in Oil-in-Water Emulsions

Our group has recently observed a nonlinear tendency in antioxidant capacity of different hydroxytyrosol fatty acid esters in fish oil-in-water emulsions, where a maximum of antioxidant efficiency appeared for hydroxytyrosol octanoate. These results appear to disagree with the antioxidant polar paradox. Because the physical location of the antioxidants in an oil-water interface has been postulated as an important factor in explaining this behavior, we have prepared a series of tyrosol and hydroxytyrosol fatty acid esters with different chain length and studied their surface-active properties in water, because these physicochemical parameters could be directly related to the preferential placement at the interface. We have found that tyrosol and hydroxytyrosol fatty acid esters are relevant surfactants when the right hydrophilic-lipophilic balance (HLB) is attained and, in some cases, as efficient as emulsifiers commonly used in industry, such as Brij 30 or Tween 20. Moreover, a nonlinear dependency of surfactant effectiveness is observed with the increase in chain length of the lipophilic antioxidants. This tendency seems to fit quite well with the reported antioxidant activity in emulsions, and the best antioxidant of the series (hydroxytyrosol octanoate) is also a very effective surfactant. This potential explanation of the nonlinear hypothesis will help in the rational design of antioxidants used in oil-in-water emulsions.

Interactions and antioxidant stability of sesamol in dry-emulsions

Dry emulsions prepared from saccharose (SAC), Labrafil M 1944 CS, sesamol (SEOH), and hydro- xypropylmethylcellulose (HPMC) or sodium caseinate (SC) by grinding or dissolution, and different desiccation tech- niques (spray (SD)- or freeze (FD)-drying, or heating at 60 C) were investigated to determine possible interactions between mixture components. The goal of this study was to determine the best formulation which will regenerate per- fectly, after water dilution of dry emulsions, the initial liquid emulsion with the same characteristics that before drying. The morphological state of SAC and dry emulsions were determined by scanning electron microscopy analysis (SEM) analysis. Glass transition temperature, and melting (endo- thermic), decomposition (endothermic), oxidation (exo- thermic) peak temperatures and enthalpies were measured by differential scanning calorimetry (DSC). The antioxidant activity of emulsions was evaluated through their ability to reduce 1,1-diphenyl-2-picrylhydrazil (DPPH) free radical. SEM analysis showed that SD-prepared, SC-containing dry emulsions formed better spherical particles with smooth surface at about 5 lm diameter as compared to emulsion containing HPMC. These former emulsions also showed more thermal stability by DSC. The combined results of the three analytical techniques emphasized the importance of the dry emulsion process regarding the efficiency and the ther- mal stability of antioxidant substances. A specific physical and/or chemical combination (such as hydrogen bond) suf- ficiently stable, at about 150 C, could be suggested when the technique used for dry emulsion preparation was SD. After water dilution, this dry emulsion obtained from quaternary mixture: SAC, Labrafil, SEOH and SC, will regenerate the initial liquid emulsion with the same characteristics that before drying.

Procyanidin Fractions from Pine (Pinus pinaster) Bark: Radical Scavenging Power in Solution, Antioxidant Activity in Emulsion, and Antiproliferative Effect in Melanoma Cells

Pine (Pinus pinaster) bark is a rich source of procyanidin oligomers. From a total polyphenolic extract, we have generated fractions of different procyanidin composition. The mixtures, devoid of gallate esters, were active as free radical scavengers against ABTS(*+), DPPH, and HNTTM. Pine bark fractions were tested for antioxidant activity in solution (hydrogen donation and electron transfer) and emulsion (inhibition of lipid peroxidation) and compared with their galloylated counterparts from grape origin. While galloylation clearly influenced the free radical scavenging efficiency in solution, it did not seem to play a determinant role in protection against lipid peroxidation in emulsion. The fractions were very mild inhibitors of cell proliferation. Because gallate esters appear to interfere with crucial cell functions, gallate free pine procyanidins may be the innocuous chemopreventative agents of choice for many applications in food and skin protection.

Antioxidant activity of acerola extracts

West Indian cherries or acerola fruits (Malpighia glabra L.) are very rich in ascorbic acid, and also contain flavonoids and anthocyanins. Therefore, their antioxidant activity is interesting. Aqueous and methanolic acerola extracts increased the stability of β-carotene-linoleic acid emulsions against oxidation. Flavonoids and anthocyanins obviously enhanced the effect of ascorbic acid. The effect of natural acerola antioxidants was comparable to that of phenolic antioxidants, such as ferulic acid. During the determination of antioxidant activity in emulsions, carotene was destroyed following a complex kinetics in the beginning of oxidation, but the zeroth order kinetics in later stages of oxidation.