Phenolic Stabilizers Research Articles

He Impact of Different Tannin to Anthocyanin Ratios and of Oxygen on the Phenolic Polymerisation Over Time in a Wine-like Solution

Colour and phenolic stability during ageing are influenced by the levels of distinct classes of phenolics in young red wines. The ratios between different classes of phenolic compounds also determine the colour and phenolic development of red wines. The present study evaluated the impact of forced oxidation on different anthocyanin/tannin (A/T) extracts and its consequent effect on the colour and phenolic evolution over time. The results showed that higher contents of seed tannins could enhance phenolic polymer formation, especially in the presence of oxygen. The addition of oxygen seemed to favour certain polymerisation reactions between tannins, leading to higher concentrations of monomeric anthocyanins in solution. A slower oxygen consumption was also observed as the phenolic composition of the wine-like extract evolved over time.

Characterization of rare virgin olive oils cultivated in southern Tunisia during fruits development process: major compounds and oxidative state in tandem with chemometrics

The present study reports the olive oil quality properties, namely free fatty acid, peroxides index, purity properties [fatty acid and triacylglycerol (TAG) composition], antioxidant compounds (total phenol, carotenoid and chlorophyll content) and oxidative stability. These analyses were performed for three rare cultivars grown in southern Tunisia (region of Tataouine). All the samples have presented good quality according to the international olive council norms. Nevertheless, there was a difference in many of the evaluated parameters as a function of ripening stages and cultivars. The oleic acid and linoleic acid amounts of olive oils increased with the ripening progress, with the highest rates were found in Fakhari cultivar. The most abundant triacylglycerols of olive oils were OOO, POO, LOO + PLnP, PLO + SLL and POP. Moreover, a general decrease (p < 0.05) of the total phenolic content, pigments content and oxidative stability were observed during maturation. The principal component analysis was used to classify nine olive oils samples depending on cultivars and maturity degree.

Dynamic changes in targeted phenolic compounds and antioxidant potency of carob fruit (Ceratonia siliqua L.) products during in vitro digestion

Carob fruit is considered as a rich source of phenolics that are linked with potent health effects. The aim of this work was to study the effect of a triple-step digestion on the stability of phenolics and antioxidant potency in carob products. Results showed that the gastric and intestinal steps induced the most significant changes in the stability of pure phenolics; their recovery ranged between 61 and 88% at oral, 40–87% at gastric and 16–57% at intestinal step. Regarding to the carob products, the yield of phenolic contents were ranged from 0.83 to 1.41 for gastric and from 0.43 to 0.82 for intestinal phase. The counterpart yield of antioxidant potency was 0.84–1.66 and 0.48–0.67, respectively. HPLC analysis also disclosed interesting findings; the stability of phenolics is strongly influenced by their chemical structure. In general, the phenolic acids are quite resistant under digestion procedure, whereas the flavonols are mostly degraded when they were subjected into digestion. Results points out that the carob phenolics are degraded, released from food matrix or attached to other food or digestive juice constituents. Furthermore, the critical role of food matrix was underlined as the food components had a protective effect against pH changes and enzymatic activities along digestion.

Plant antimicrobial polyphenols as potential natural food preservatives

The growing demand for natural food preservatives in the last decade has promoted investigations on their application for preserving perishable foods. In this context, the present review is focused on discussing the prospective application of plant extracts containing phenolics or isolated plant phenolics as natural antimicrobials in foods. Plant essential oils are outside the scope of this review since utilization of their antimicrobial activity for food preservation has been extensively reviewed. Although the exact antimicrobial mechanisms of action of phenolic compounds are not yet fully understood, it is commonly acknowledged that they have diverse sites of action at the cellular level. Antimicrobial phenolics can be added directly to the formulation of perishable food products or incorporated into food-contact materials to release them in the immediate zone of perishable foods. Edible coatings or active food packaging materials can thus be used as carriers of plant bioactive compounds. These materials could be an interesting delivery system to improve the stability of phenolics in foods and to improve the shelf life of perishable foods. This review will thus provide an overview of current knowledge of the antimicrobial activity of phenolic-rich plant extracts and of the promises and limits of their exploitation for the preservation of perishable foods. © 2018 Society of Chemical Industry.

Impact of Time, Oxygen and Different Anthocyanin to Tannin Ratios on the Precipitate and Extract Composition Using Liquid Chromatography-High Resolution Mass Spectrometry

Wine colour and phenolic stability over time are influenced by the amount and nature of phenolics in young wines. The ratio between different phenolic compounds can also be determinant in the colour and phenolic development of red wines. Three different anthocyanin to tannin ratios extracted in a wine-like system were saturated with oxygen several times during sample storage. A LC-HRMS method was used to evaluate the impact of a forced oxidation and of the different extracts on the wine-like composition and on the precipitate formed over time. The extract composition was found to be the most determinant factor for the precipitate formed. Time was also found to be a relevant factor according to the precipitate composition.

Effect of different encapsulating agent combinations on physicochemical properties and stability of microcapsules loaded with phenolics of plum (Prunus salicina lindl.)

Microencapsulation improves the bioavailability and stability of phenolic compounds, while encapsulating agents affect the quality of microcapsules. In order to improve the stability and application range of phenolics from plum (Prunus salicina Lindl.), microencapsulation was applied by using spray drying method. The present work evaluated the influence of maltodextrin/gum arabic (MD/GA),maltodextrin/gelatin (MD/GEL), maltodextrin/chitosan (MD/CHI) and maltodextrin/β-cyclodextrin/gum arabic (MD/β-CD/GA) on physicochemical properties and stability of microcapsules loaded with phenolics of plum. These four kinds of encapsulating agent combinations significantly improved the product yield and storage stability of the microcapsule powder, but there were differences among them in microencapsulated efficiency, microstructure and color. Using encapsulating agents markedly increased the glass transition temperature (Tg) of spray-dried powders, and Tg of the powder was positively correlated with its product yield. Furthermore, the powder prepared by MD/CHI had the best stability, and the retention rate of total phenol was 94.60% after storage at 25°C for 60days. The powder prepared by MD/GA and MD/β-CD/GA preferably retains the original red color of plum, and can be used as natural nutrient red pigments in the food industry.

Comparative study of high hydrostatic pressure and high temperature short time processing on quality of clear and cloudy Se-enriched kiwifruit juices

Abstract Selenium (Se) distribution was investigated and a comparative study was carried out into the effects of high hydrostatic pressure (HHP) and high temperature short time (HTST) treatments on quality for both clear and cloudy Se-enriched kiwifruit juice (clear-SKJ, cloudy-SKJ). Organic Se which accounted for 62.32% has a wider distribution than inorganic Se in kiwifruits and mainly comprising Se-protein and Se-polysaccharide. The process of separating kiwifruit pomace from juice caused significant decline in Se content with 43.07% and 49.04% in cloudy and clear juices respectively, and the sterilization process of HHP and HTST significantly decreased the Se contents from 50.46 ± 0.42 μg/kg to 39.63 ± 0.51 μg/kg and 37.93 ± 0.08 μg/kg in cloudy-SKJ, respectively. During the storage period, HTST- and HHP-processed juices showed no significant differences in total Se content, and similarly for certain chemical-physical qualities of total soluble solids, titratable acid, viscosity and pH. In addition, HHP (500 MPa/10 min) and HTST (110 °C/8.6 s) treatments inactivated yeasts and molds (Y&M) completely and sustained total aerobic bacteria (TAB) counts below 2.0 Log10 CFU/mL which guaranteed the microbiological safety in clear-SKJ during storage at 4 °C and 25 °C for 42 days, but TAB counts were detected >2.0 Log10 CFU/mL which demonstrated a shorter shelf life in cloudy-SKJ under the same storage conditions. Moreover, the HHP-treated sample showed better quality characteristics compared with the HTST-treated sample during 42-day storage except for total phenols and the storage time at 4 °C was more conducive to the preservation of the juices after HHP and HTST treatments. Industrial relevance Se-enriched kiwifruit juice is a promising Se-enriched beverage product which has high nutrition and economic value. The results obtained underline the different effects of HHP and HTST on quality and storage stability of Se retention, microorganisms, color, total phenols, chlorophyll and other quality-related aspects. This study may provide technical support for the application of HHP or HTST in the Se-enriched kiwifruit juice industry. Furthermore, a non-thermal technique which can improve functional juice properties to meet the demand of consumers for healthier products is provided in this study.

Functional and Rheological Properties of Yam (&lt;em&gt;Dioscorea rotundata&lt;/em&gt;) Mucilage

The objective of the present study was to evaluate the functional and rheological properties of mucilage of Hawthorne bread of yam ( Dioscorea rotundata ). The extraction of mucilage was performed by continuous bubbling method and then its functional (solubility at 30 to 70°C, water absorption index, water solubility index, swelling capacity, stability and clarity of the paste, oil absorption capacity, emulsifier activity, stability of emulsion, total phenols and antioxidant capacity) and rheological (stationary test and viscoamilogram) properties were evaluated. The results indicate a greater solubility (96.96% to 30°C and 88.76% to 70°C) and stability of emulsion (68.89%); however, total phenol content and antioxidant capacity lower to other mucilage, possibly due to the extraction method employed (bubbling). The method that best represented the rheological behavior of suspensions of mucilage of yam was that of Oswald de Waele, categorizing it as dilatant fluid (n>1) and the viscoamilogram demonstrates the low starch content in mucilage, showing a setback of 11.43 mPa.s, which indicates high stability of this polymer. The functional properties show the potential of mucilage as emulsifier and its easy inclusion in food matrices.

Photooxidative stability provided by condensed tannin additives in acrylic-based surface coatings on exterior exposure

Condensed tannins, also known as proanthocyanidins, have been added as functional additives to acrylic-based clear coatings to promote polymer coating longevity and also stabilize timber color on accelerated and exterior weathering. When added at 20% compared to commercial hindered amine light stabilizers (HALS) and phenolic stabilizers used at comparable coating loadings. Other tannin chemical modifications such as methylcarboxylate groups were also associated with greater coating longevity beyond that achieved with the synthetic UV and antioxidant additives. This study has also revealed that tannin addition to acrylic coatings can act to photostabilize timber coloring on exterior exposure. While tannin use can contribute color to coatings, any color was rapidly bleached on UV exposure with a dependency on tannin content, degree of modification, and coating formulation pH. Moreover, through manipulating tannin addition levels, this tannin decolorization could offset typical wood darkening associated with UV exposure to provide low or no wood color change over longer exposure periods. With the photooxidative stability efficacy of tannins established on exterior exposure, condensed tannins in native and modified form offer potential as sustainable functional additives for the coatings sector.

Application of double filtration with activated carbon for the removal of phenols in drinking water treatment processes

Abstract The primary source of the discharge of phenols into the environment is industrial activity, such as the production of pharmaceuticals, plastics, and pesticides, being the majority discharged into surface water sources, reaching concentrations around 0.001 to 0.400 mg/L. These compounds are considered a priority contaminant due to their toxicity to aquatic life and effects on human health. The presence of phenols even at low concentrations generates flavour and odour in drinking water. Due to the molecular stability and solubility of phenols in water, their removal by conventional water treatment methods is inefficient. However, adsorption with granular activated carbon (GAC), after conventional filtration with sand and anthracite, is an efficient technique for the reduction of organic compounds such as phenols. This paper studied the effect of applying double filtration to the reduction of phenols present in the filtered water of a conventional drinking water treatment plant, using two types of GAC (vegetable and mineral) and three GAC:Sand configurations (100:00; 00:100; 50:50). The configurations with GAC showed an efficient reduction of turbidity, organic matter indicator variables (UV254 absorbance and total organic carbon) and phenols, the mineral GAC being the most efficient GAC.

Enhanced thermo-oxidative stability through covalent attachment of hindered phenolic antioxidant on surface functionalized polypropylene

In order to prolong the thermo-oxidative stability of polypropylene and prevent antioxidant loss, this research details an effective approach to prepare polymeric antioxidant via surface functionalization of polypropylene with long-chain macromolecules containing hindered phenolic stabilizers. The polymeric antioxidant (PPNA) is prepared by amide bond formation between phenolic stabilizer containing carboxylic acid moiety and amine functionalized polypropylene (PPNH2). Test results confirmed surface changes through plasma treatment, amine and antioxidant modification. The resultant PPNH2 and PPNA exhibit reduced crystallinity while the crystallization temperature shifts toward higher values, suggesting simultaneous effects of steric hindrance and nucleation of long-chain structures. Immobilization of phenolic stabilizer results in improving thermo-oxidative stability of polypropylene. Subsequently, PPNA was used to prepare PP/PPNA blends to evaluate free radical scavenging ability and resistance to extraction. The blends demonstrate superior thermal stability and low volatility compared to stabilized polypropylene with Irganox 1010, indicating uniform distribution due to comparability. The synthesized polymer-bound antioxidant have the potential to be the material of choice as stabilizer concentrate for packaging, coating and thin film applications.

The impact of high voltage electrical discharge plasma on the chromatic characteristics and phenolic composition of red and white wines

Abstract The cold plasma is an emerging electrotechnology for the improvement of food safety without loss of physicochemical or sensory properties. The purpose of this study was to evaluate the effects of plasma treatments on the chromatic characteristics and phenolic composition of red and white wines. The red wine Cabernet Sauvignon and white wine Grasevina were treated with high voltage electrical discharge plasma considering the variations in frequency (60, 90 and 120 Hz) and processing time (3, 5 and 10 min). Total phenolics, total anthocyanins, total tannins and chromatic characteristics were analyzed by spectrophotometry while free anthocyanins, phenolic acids and flavan-3-ols by the HPLC-UV/Vis. Obtained results illustrated that plasma treatments have influenced the stability of phenolic compounds in wines without major changes in color parameters. Also, among two different processing parameters, the duration time was the most significant factor inducing changes on wines. Industrial relevance High voltage electrical discharge plasma has been shown to affect the stability of wine phenols without any significant change in the color. An increase in the concentration of certain phenolic compounds in white wine suggest that this technique could be used in the wine industry as an alternative technique for enhancing the oxidative stability of wine and consequently the wine quality during the aging process.

Effect of Cold Atmospheric Plasma on Inactivation of Escherichia coli and Physicochemical Properties of Apple, Orange, Tomato Juices, and Sour Cherry Nectar

In this study, orange, tomato, apple juices, and sour cherry nectar were exposed to an atmospheric pressure plasma jet. Plasma treatments were carried out using air as a precursor under constant gas flow (3000 L/h) at 650 W for different treatment times (30, 60, 90, and 120 s). After plasma processing, reduction of Escherichia coli, Hunter’s color parameters (L*, a*, b*), total phenolic content, and pH values were evaluated. The inactivation effect of cold atmospheric plasma (CAP) was investigated on E. coli, and the highest significant reductions were achieved in apple juice (4.02 ± 0.03 log CFU/mL) followed by sour cherry (3.34 ± 0.09 log CFU/mL), while the values in orange (1.59 ± 0.17 log CFU/mL) and tomato juices (1.43 ± 0.22 log CFU/mL) were lower, which could be attributed to the food matrix. Color parameters, except for apple juice, did not show significant changes after processing. Compared to untreated juice, plasma treatment yielded higher phenolic content from 10 to 15%, while pH values did not change significantly and the temperature remained below 40 °C after all plasma treatments. This study showed that CAP treatment had positive influences on phenolic stability and color change in all samples regardless of food intrinsic factors, while it was more effective on bacterial inactivation in clear juices than turbid ones. Our results indicate that atmospheric plasma appears to be a promising technology for microbial inactivation without causing undesirable changes in food product.

Impact of grape dehydration process on the phenolic composition of wines during bottle ageing

The effect of grapes dehydration on, phenolic profile was evaluated in wines during bottle ageing. Wines produced with Cabernet Sauvignon and Merlot grapes, dehydrated in different percentages (30 and 40%) under controlled conditions, were analyzed by spectrophotometric and chromatographic assays during 22 months of storage. The phenolic profile of the wines and their evolution during bottle ageing was different according to the grape variety and the percentage of dehydration applied. An increase in the concentration of phenolic acids (gallic, protocateic, coumaric) and flavonols (quercetin, campferol, and myricetin) was observed in all samples during bottle ageing, along with a reduction of anthocyanin (delphinidin, malvidin, peonidine, and cyanidin 3-O-glucoside) and flavanols (+)-catechin and (−)-epicatechin). Main changes in the phenolic composition of all wines occurred during the 10th and 13th month, but the changes in wines produced from dried grapes were softer than control wines, indicating that dehydration process improve the wine phenolic stability and permit long periods of ageing for this kind of wines. Practical applications Different wine regions utilize the grape dehydration to produce differentiated and high value-added wines. This study provides an overview on the effect of grape dehydration process under controlled conditions on wine phenolic evolution during bottle ageing. The results provide relevant information about the storage time required for this kind of wine to improve its commercialization and consumption.

Structure, thermal stability, antioxidant activity and DFT studies of trisphenols and related phenols

Two kinds of trisphenols have been successfully synthesized and their structures were confirmed by IR spectra, 1HNMR, 13CNMR, mass spectra and X-ray diffraction. They exhibited better thermal stability than both monophenol and bisphenols due to their higher molecular weight. Moreover, their antioxidant activities have been investigated in lubricant oil using PDSC and RBOT. The results showed that the o-trisphenol 3b exhibited the best antioxidant activity while the p-trisphenol 3a was the worst. In addition, their relationship between structures and properties has been further explored by a series of DFT calculations including the BDE values, the IP values and the Gibbs free energy barriers for the reaction between phenols and methylperoxyl radicals.

Composite flour blends: Influence of particle size of water chestnut flour on nutraceutical potential and quality of Indian flat breads

Different sieve particle sizes P1 (Whole), P2 (≤0.212 mm) and P3 (≤0.125 mm) of water chestnut flour (WCF) were studied for proximate composition, mineral content, physico-chemical, functional, pasting and antioxidant properties in comparison to refined wheat flour (WF). WCF had significantly higher levels of fiber, resistant starch, mineral (K, Mg, Zn, and Cu), phenolics and flavonoids than WF in the order (P1 > P2 > P3 > WF). Increase in flour fineness decreased antioxidant activity (P1 > P2 > P3) with P1 having highest phenolic (4.72 mg GAE/g), flavonoid (2.46 mg QE/g) content. Pasting properties of P1 were significantly lower than WF but significantly increased with increase in flour fineness. Quality of flat bread produced from WCF-WF blends significantly varied with particle size and blending. Bake loss and baking time significantly decreased while shrinkage increased with decrease in particle size. L* value decreased with blending but showed an irregular trend with variation in particle size. (WF > P2 ≥ P3 > P1). Baking decreased DPPH scavenging activity more in WF bread (46.68%) than WCF bread (P1 = 17.71%, P2 = 16.45%, P3 = 19.63%). Baking decreased total phenolic and flavonoid content by 49 and 20% in wheat & 38 and 16% in WCF respectively while significantly increased the resistant starch content in the order (P3 > P2 > P1 > WF). This shows better retention of antioxidant activities and greater stability of WCF phenolics than WF phenolics during baking. Sensory analysis showed WCF breads had fair acceptability due to their characteristic flavor. Thus, gluten free WCF bread is also antioxidant rich with ample resistant starch content than WF breads.

Seed priming improves chilling tolerance in chickpea by modulating germination metabolism, trehalose accumulation and carbon assimilation

Chilling stress is one of the major abiotic stresses affecting chickpea productivity worldwide. This study evaluated the potential role of seed priming in improving resistance to chilling stress in chickpea (cv. Punjab, 2008). The priming treatments involved soaking seeds of chickpea cultivar Punjab 2008 in either water for 8 h (on-farm priming), aerated water (hydropriming) for 18 h, or CaCl2 solution (ψs −1.25 MPa; osmopriming) for 18 h. Primed and untreated seeds were grown either at 18/15 °C (control) or 13/10 °C (chilling stress). Chilling stress suppressed the growth of chickpea while seed priming mitigated the adverse effects of chilling stress by improving stand establishment, growth, water relations, photosynthesis, α-amylase activity, sugar metabolism, antioxidant enzyme activity, membrane stability, and leaf accumulation of proline, nitrogen, potassium and soluble phenolics. Seed priming also improved the performance of chickpea under optimal (control) conditions. The overall order of improvement in resistance to chilling by using seed priming was osmopriming > hydropriming > on-farm priming. Osmopriming improved seedling dry weight, specific leaf area, leaf CO2 net assimilation rate, maximal photochemical efficiency of PSII, α-amylase activity, trehalose content and leaf relative water content by 10, 22, 17, 20, 73, 48 and 7%, respectively, relative to the non-primed control under chilling stress. Under optimal temperature conditions, the corresponding values were 30, 32, 16, 10, 83, 75 and 5%, respectively. Sugar metabolism, especially trehalose content, was strongly linked with stand establishment, photosynthesis, antioxidant potential (under chilling stress) and plant biomass. Overall, seed priming improved chickpea performance under both optimal temperature conditions and chilling stress through better germination metabolism and the accumulation of trehalose, which protected from oxidative damage and helped to maintain carbon assimilation and seedling growth.

Effects of Juice Matrix and Pasteurization on Stability of Black Currant Anthocyanins during Storage.

The effects of juice matrix and pasteurization on the stability of total phenols and especially total and individual anthocyanins were examined in black currant (BC) juice and mixtures with apple, persimmon, and peach juices at 4 °C and 20 °C. Total phenol content decreased in all juices at both temperatures but there was a trend to lower levels in unpasteurized over pasteurized juices. Differences in the decline of total anthocyanins between pasteurized and unpasteurized juices varied according to the juice type and the storage temperature. At 4 °C storage, anthocyanins declined in all juices according to pseudo 1st-order kinetics and there were only small differences in the rates between pasteurized and unpasteurized juices. However, at 20 °C, although pasteurized and unpasteurized BC juices and pasteurized mixed juices followed pseudo 1st-order kinetics, there was a different pattern in unpasteurized mixed juices; a rapid initial decline was followed by a slowing down. The effect of the added juice on anthocyanin decline was also different at either temperature. At 4 °C, the anthocyanins decreased faster in mixed juices than BC juice alone, but at 20 °C, at least in pasteurized mixed juices, the decline was similar or even slower than in BC juice; there were only small differences among the 3 mixed juices. At 20 °C, in pasteurized and unpasteurized BC juices, the rate of decrease was essentially the same for all 4 individual anthocyanins but in the mixed juices the 2 glucosides decreased significantly faster than the 2 rutinosides.

Wheat-water chestnut flour blends: effect of baking on antioxidant properties of cookies.

Proximate composition, mineral content, functional, pasting and antioxidant properties of water chestnut flour (WCF) were compared with refined wheat flour. WCF showed higher phenolic (4.25gGAE/1000g), flavonoid (1.92g QE/1000g) and mineral content (K, Mg, Zn, Cu) than wheat flour. WCF showed greater retrogradation tendency but lower peak viscosity than wheat flour. Wheat flour - WCF blends and cookies were evaluated for water activity, physical & textural properties. Water activity of cookies decreased significantly (0.415-0.311) with increase in level of WCF in wheat flour. Total phenolic content, flavonoid content and antioxidant activity (DPPH• scavenging capacity, FRAP) of WCF - wheat flour blends as well as their cookies was also determined. Baking led to a greater increase in DPPH• scavenging capacity of WCF cookies (33.8%) than WF cookies (25%). Baking had a similar effect on FRAP value. Wheat flour cookies showed a decrease of 51%, and 62% while WCF cookies showed a decrease of 36%, and 34% in TPC and TFC values respectively. WCF cookies thus showed better retention of antioxidant activities suggesting greater stability of WC phenolics than wheat phenolics. Sensory analysis showed cookies made from water chestnut (100%) had fair acceptability due to their characteristic flavor. Thus, water chestnut flour serves both as a gluten free as well as antioxidant rich flour for production of cookies.

Effect of processing technologies and storage conditions on stability of black currant juices with special focus on phenolic compounds and sensory properties.

Juice was pressed from black currants without enzyme treatment (NEB=Non-Enzymatic Berry) followed by re-pressing of the residue with enzymes (EPR=Enzymatic Press Residue) and the results were compared to the conventional enzyme-aided berry pressing (EB=Enzymatic Berry). EPR-juice had 9- and 5-fold higher contents of phenolic compounds compared with the NEB- and EB-juices, respectively. Effect of the low content and stability of phenolics was noticed as loss of the visual color in the NEB-juice during storage. The decrease in monomeric anthocyanins and the increase in phenolic acids were most severe in the NEB-juice, whereas the most significant decline in hydroxycinnamic acid derivatives occurred in the enzyme-treated juices. Storage in light induced less change in the phenolic composition in EPR-juice than in the two other juices. The study gave new knowledge on changes in individual metabolites, in sensory properties and in the shelf life of berry juices.