Process and storage stability of anthocyanins and non-anthocyanin phenolics in pectin and gelatin gels enriched with grape pomace extracts

Effect of maltodextrin and Persian gum as wall materials and tannic acid as copigment on some properties of encapsulated sour cherry anthocyanin microcapsules

Due to the instability of anthocyanins, their application as natural colorants is limited. To improve their stability, anthocyanins extracted from sour cherry were copigmented with tannic acid at varying molar ratios. The optimal anthocyanin:copigment molar ratio was determined to be 1:0.25. Subsequently, both non-copigmented and copigmented anthocyanins (using the optimal tannic acid molarity) were spray-dried with either maltodextrin alone (T1 and T2) or a combination of maltodextrin and Persian gum (T3 and T4). The anthocyanin retention in T2 and T4 was approximately 53 % and 38 %, respectively, which were higher than in the non-copigmented samples. All powders demonstrated high encapsulation efficiency (>90.37 %). Stability tests on the anthocyanins conducted over 28 days indicated that light exposure had no effect on the reduction of anthocyanin content when maltodextrin was used. Thus, the copigmentation of anthocyanins with tannic acid, combined with encapsulation in maltodextrin, presents a promising method for producing a stable natural colorant.

Exploring the influence of S. cerevisiae mannoproteins on wine astringency and color: Impact of their polysaccharide part

The impact of the polysaccharide moiety of mannoproteins (MPs) on the color and astringency of red wines was studied respectively through spectrophotometry and their impact on tannin interactions with BSA. To this end, MPs with conserved native structures from four different Saccharomyces cerevisiae strains were used: a Wild-Type strain (BY4742, WT) taken as reference, mutants ΔMnn4 (with no mannosyl-phosphorylation) and ΔMnn2 (linear N-glycosylation backbone), and a commercial enological strain. MPs affected tannin-BSA interactions by delaying aggregation kinetics. To achieve it, a well-balanced density/compactness of the polysaccharide moiety of MPs was a key factor. MP-WT and MP-Mnn2 acted as weak copigments and induced a slight increase in the absorbance of Malvidin-3-O-Glucoside. The same MPs also promoted a synergistic effect during the copigmentation of Quercetin-3-O-Glucoside with Malvidin-3-O-Glucoside. The intensity of these hyperchromic effects was related to the accessibility of anthocyanins to negatively charged mannosyl-phosphate groups within the polysaccharide moiety.

Anthocyanins: Modified New Technologies and Challenges

Anthocyanins are bioactive compounds belonging to the flavonoid class which are commonly applied in foods due to their attractive color and health-promoting benefits. However, the instability of anthocyanins leads to their easy degradation, reduction in bioactivity, and color fading in food processing, which limits their application and causes economic losses. Therefore, the objective of this review is to provide a systematic evaluation of the published research on modified methods of anthocyanin use. Modification technology of anthocyanins mainly includes chemical modification (chemical acylation, enzymatic acylation, and formation of pyran anthocyanidin), co-pigmentation, and physical modification (microencapsulation and preparation of pickering emulsion). Modification technology of anthocyanins can not only increase bioavailability and stability of anthocyanin but also can improve effects of anthocyanin on disease prevention and treatment. We also propose potential challenges and perspectives for diversification of anthocyanin-rich products for food application. Overall, integrated strategies are warranted for improving anthocyanin stabilization and promoting their further application in the food industry, medicine, and other fields.

Antioxidant Compound Adsorption in Polyvinylpolypyrrolidone from Chilean Carménère, Cabernet Sauvignon, and Merlot Grape Pomaces as Potential By-Products

Grape pomace (GP) is a by-product resulting from the winemaking process and its potential use as a source of bioactive compounds is well known. The GP bioactive compounds can be retained in the well-known polyvinylpolypyrrolidone (PVPP), industrially used in the clarification and stabilization of wine and other drinks. Thus, the polyphenolic compounds (PC) from the Chilean Carménère, Cabernet Sauvignon, and Merlot GP were extracted, and their compositions and antioxidant capacities (ORAC-FL) were determined. In addition, the retention capacity of the PC on PVPP (PC-PVPP) was evaluated. The bioactivities of GP extracts and PC-PVPP were estimated by the agar plate inhibition assay against pathogenic microorganisms. Results showed a high amount of TPC and antioxidant capacity in the three ethanolic GPs extracts. Anthocyanins, flavan-3-ol, and flavonols were the most abundant compounds in the GP extract, with retentions between 70 and 99% on PVPP. The GP extracts showed inhibition activity against B. cereus and P. syringae pv. actinidiae but the GP-PVPP had no antimicrobial activity. The high affinity of the identified PCs from GPs on PVPP polymer could allow the design of new processes and by-products for the food or cosmeceutical industry, promoting a circular economy by reducing and reusing wastes (GPs and PVPP) and organic solvents.

Characterization of Nasco grape pomace-loaded nutriosomes and their neuroprotective effects in the MPTP mouse model of Parkinson’s disease

Grape pomaces have recently received great attention for their richness in polyphenols, compounds known to exert anti-inflammatory and antioxidant effects. These pomaces, however, have low brain bioavailability when administered orally due to their extensive degradation in the gastrointestinal tract. To overcome this problem, Nasco pomace extract was incorporated into a novel nanovesicle system called nutriosomes, composed of phospholipids (S75) and water-soluble maltodextrin (Nutriose® FM06). Nutriosomes were small, homogeneously dispersed, had negative zeta potential, and were biocompatible with intestinal epithelial cells (Caco-2). Nasco pomace extract resulted rich in antioxidant polyphenols (gallic acid, catechin, epicatechin, procyanidin B2, and quercetin). To investigate the neuroprotective effect of Nasco pomace in the subacute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson’s disease (PD), Nasco nutriosomes or Nasco suspension was administered intragastrically and their neuroprotective effects were evaluated. Degeneration of nigro-striatal dopaminergic neurons induced by subacute MPTP treatment, the pathological hallmark of PD, was assessed through immunohistochemical evaluation of tyrosine hydroxylase (TH) in the caudate-putamen (CPu) and substantia nigra pars compacta (SNc), and the dopamine transporter (DAT) in CPu. Immunohistochemical analysis revealed that Nasco nutriosomes significantly prevented the reduction in TH- and DAT-positive fibres in CPu, and the number of TH-positive cells in SNc following subacute MPTP treatment, while Nasco suspension counteracted MPTP toxicity exclusively in SNc. Overall, these results highlight the therapeutic effects of Nasco pomace extract when administered in a nutriosome formulation in the subacute MPTP mouse model of PD and validate the effectiveness of the nutriosome preparation over suspension as an innovative nano-drug delivery system for in vivo administration.

Delivery system for grape seed extract based on biodegradable pectin-Zn-alginate gel particles

Pectin-Zn-alginate gel particles from callus culture pectin with increased linearity and decreased rhamnogalacturonan I branching and degree of methylesterification had a higher gel strength and encapsulation capacity. An increase of the alginate concentration led to an increase in the particle gel strength. The grape seed extract (GSE) loaded and empty particles swelled slightly in the simulated gastric fluid (SGF) and gradually in the intestinal (SIF) fluid. The swelling degrees of the GSE-loaded and empty particles in the simulated colonic fluids (SCF) were decreased in the range SCF-7.0 (pH 7.0 + pectinase) > SCF-5.3 (pH 5.3 + pectinase) > SCF-2.3 (pH 2.3 + pectinase). The FTIR spectra indicated that GSE was embedded in the composite particles. Negligible leakage of GSE in SGF was shown. The increase in GSE release in SIF was due to the decrease in particle gel strength and increased swelling degree. The GSE release in fluids simulating the colon inflammation (SCF-2.3 and SCF-5.3) was similar, and it was lower than that in the SCF-7.0 simulating a healthy colon due to the increased gel strength. The percentage release of GSE increased slightly after exposure to different pH. Pectin-Zn-alginate hydrogel systems may be promising candidates for colon-targeted GSE delivery systems.

Fortification of Pectin/Blackberry Hydrogels with Apple Fibers: Effect on Phenolics, Antioxidant Activity and Inhibition of α-Glucosidase

The objective of this study was to prepare hydrogels based on pectin and blackberry juice and additionally to fortify those hydrogels with apple fiber. For that purpose, two types of pectin (low methoxylated and high methoxylated) were used, and fortification was conducted with the addition of 10% of apple fiber. The hydrogels were evaluated for phenolic compounds, antioxidant activity and inhibition of α-glucosidase. In addition, the stability of these parameters after 8 months of storage was evaluated. Pectin type and addition of apple fiber had an impact on investigated parameters. Low methoxylated pectin hydrogels had a higher concentration of anthocyanins than high methoxylated pectin hydrogels, while the addition of apple fibers caused a decrease in anthocyanin content. However, fortified hydrogels had higher antioxidant activity due to the presence of phenolics from apple fibers. The results showed that anthocyanins were more favorable in inhibiting α-glucosidase because samples with higher anthocyanins concentration had lower IC₅₀ values. Obtained hydrogels can be used as intermediate products or ingredients (like fruit fillings or spreads) for the improvement or development of novel food products to increase their fiber content and antioxidant potential.

Development and Characterization of Powdered Antioxidant Compounds Made from Shiraz (Vitis vinifera L.) Grape Peels and Arrowroot (Maranta arundinacea L.)

Grapevine (Vitis vinifera L.) is a plant containing many phenolic compounds, mostly distributed in the peel, pulp, and seeds. This study evaluates the centesimal composition and bioactive compounds in Shiraz grape (Vitis vinifera) peels using spectrophotometric and UHPLC techniques and develops different formulations of compound powders from the peels and arrowroot using conventional drying technology. The results demonstrate that Shiraz grape skin contains significant amounts of insoluble fiber (15.3%), phenolics (157.09 ± 6.96-149.11 ± 9.27 mg GAE g-1), and flavonoids (0.75 ± 0.50-2.00 ± 0.50 mg QE g-1), with excellent antioxidant capacity observed in the alcoholic extracts. The phenolic content in the developed powdered compounds ranged from 128.32 to 139.70 mg GAE g-1. In general, the compounds showed good antioxidant capacity (IC50 = 0.17 to 0.19 μg mL-1). According to the chromatographic evaluation, it was possible to quantify gallic acid, catechin, and epicatechin, the latter of which was found in the largest quantities in the six formulations. The EV5 formulation was the most efficient in terms of phenolic compounds and protein amounts. This formulation's composition and low cost could make it viable for use in the food industry.

Effects of Cryoconcentrated Blueberry Juice as Functional Ingredient for Preparation of Commercial Confectionary Hydrogels

Hydrogels can absorb and/or retain components in the interstitial spaces due to the 3D cross-linked polymer network, and thus, these matrices can be used in different engineering applications. This study focuses on the physicochemical and textural properties, as well as bioactive compounds and their antioxidant activity stability of commercial hydrogels fortified with cryoconcentrated blueberry juice (CBJ) stored for 35 days. CBJ was added to commercial hydrogels (gelatin gel (GG), aerated gelatin gel (AGG), gummy (GM), and aerated gummy (AGM)). The samples showed a total polyphenol, anthocyanin, and flavonoid content ranging from 230 to 250 mg GAE/100 g, 3.5 to 3.9 mg C3G/100 g, and 120 to 136 mg CEQ/100 g, respectively, and GG and GM showed the lowest bioactive component degradation rate, while AGM presented the highest degradation. GG and GM samples could be stored for up to 21 days without significant changes, while the results indicated ≈15 days for the AGG and AGM samples. Thereby, CBJ offers enormous possibilities to be used as a functional ingredient due to the high nutritional values, and it allows enriching different hydrogel samples, and in turn, the structures of hydrogels protected components during in vitro digestion, enhancing the bioaccessibility after the digestion process.

Combination of copigmentation and encapsulation strategies for the synergistic stabilization of anthocyanins

Copigmentation and encapsulation are the two most commonly used techniques for anthocyanin stabilization. However, each of these techniques by itself suffers from many challenges associated with the simultaneous achievement of color intensification and high stability of anthocyanins. Integrating copigmentation and encapsulation may overcome the limitation of usage of a single technique. This review summarizes the most recent studies and their challenges aiming at combining copigmentation and encapsulation techniques. The effective approaches for encapsulating copigmented anthocyanins are described, including spray/freeze-drying, emulsification, gelation, polyelectrolyte complexation, and their combinations. Other emerging approaches, such as layer-by-layer deposition and ultrasonication, are also reviewed. The physicochemical principles underlying the combined strategies for the fabrication of various delivery systems are discussed. Particular emphasis is directed toward the synergistic effects of copigmentation and encapsulation, for example, modulating roles of copigments in the processes of gelation and complexation. Finally, some of the major challenges and opportunities for future studies are highlighted. The trend of integrating copigmentation and encapsulation has been just started to develop. The information in this review should facilitate the exploration of the combination of multistrategy and the fabrication of robust delivery systems for copigmented anthocyanins.

Hydrogels: Characteristics and Application as Delivery Systems of Phenolic and Aroma Compounds

Complex challenges are facing the food industry as it develops novel and innovative products for the consumer marketplace. Food processing and preservation are primarily based on achievement and maintenance of safety in order to protect consumers, as well as extending product shelf life under the relevant conditions of storage, transport and distribution. Maximizing retention of bioactives with recognized positive effects on health typically comes under consideration when the previous two priorities have been achieved. This review introduces the potential applications of hydrogels as delivery systems of high-value bioactives like phenolics and aromas. If they are successfully encapsulated within the gel structures, their release can be controlled, which opens a wide range of applications, not only in food, but also in the pharmaceutical and cosmetic industries. Hydrogels are three-dimensional network structures which can absorb significant amounts of water. They have the ability to thicken the system and therefore can be used to design products with desired properties. In order to preserve the valuable components, it is necessary to know their physicochemical properties, in addition to the properties of the polymer used for hydrogel preparation.

Challenges in confectionery industry: Development and storage stability of innovative white tea-based candies

The aim of this study was the development of innovative candies formulations accordant with the present trends in the confectionery industry. Steviol glycosides, sorbitol, and agave syrup were used as sucrose alternatives, while agar and pectin were included instead of gelatin for the formulation of vegan candies. Additionally, white tea extract was used as a candy base and source of bioactive compounds. Bioactive quality (total phenolic content, antioxidant capacity, epigallocatechin gallate, and caffeine content) and physicochemical (dry matter, springiness, hardness, color) parameters of candies were monitored during 4 months of storage at 4 and 22 °C. Pectin candies with the highest content of dry matter (79.8%) showed the longest shelf life, while those with agar (52.0% and 66.2%) were the most susceptible to spoilage. Candies prepared with agar were less hard (0.4 and 0.6 N) and with less elastic texture (1.5 and 3.4 mm) and showed the highest stability of physicochemical parameters during storage, while those with pectin were also less hard (0.5 N) but with more elastic texture (10.7 mm) than gelatin candies (3.6 and 4.4 mm; 2.4 and 4.1 N). Although gelatin samples were characterized with the greatest bioactive quality parameters immediately after production, they showed a higher instability of the same parameters during storage compared to the agar and pectin candies. PRACTICAL APPLICATION: According to the consumers' demands for healthier confectionery products, formulations of candies with sucrose alternatives, non-animal hydrocolloids, and natural bioactive compounds were developed. Giving a deeper insight into their physicochemical and bioactive properties, this paper could contribute to confectionery industry in development and optimization of formulations in order to obtain candies with desirable and attractive properties.

Children's liking and wanting of foods vary over multiple bites/sips of consumption: A case study of foods containing wild blueberry powder in the amounts targeted to deliver bioactive phytonutrients for children

To encourage children to frequently consume wild blueberries as part of their dietary patterns, incorporating blueberry powder into specific foods may be an effective strategy. Thus, it is important to determine appropriate types of food products that both minimize food processing-induced loss of beneficial components of blueberries (e.g., anthocyanins) and satisfy at the same time both nutritional and sensory aspects. For clinical studies assessing the health benefits of blueberry-containing food samples, it would be important to ensure children consume the entire portion of the test samples. This study, therefore, aimed at determining how sensory acceptability (liking) and psychological reward (wanting) of wild blueberry-based foods vary over multiple steps of ad libitum consumption: appearance, first bite/sip, half bite/sip, and full consumption. Five different types of foods containing the targeted amount of wild blueberry powder were prepared for sensory testing (oatmeal bar, beverage, ice pop, gummy, and cookie), and the residual amounts of total anthocyanin and chlorogenic acid were measured to confirm levels targeted to deliver bioactive amounts of these phytochemicals. Results showed that while overall liking and desire to eat did not differ among the five samples at the appearance and first bite/sip steps, they differed significantly at the end of consumption. Although children liked and wanted to consume the cookies more when compared to beverages, ice pops, and/or gummies, total anthocyanin contents were lower in cookies and gummies than in wild blueberry powder, beverage, and ice pop samples. Notably, the oatmeal bars with significant amounts of total anthocyanin and chlorogenic acid did not significantly differ from the cookies with respect to overall liking, desire to eat, and the amount consumed. In conclusion, this study shows that sensory evaluation using multiple bites/sips of ad libitum food consumption, along with a measurement of beneficial compounds, is efficient in determining appropriate vehicles for clinical studies of wild blueberry-containing foods.

Changes in Polyphenolics during Storage of Products Prepared with Freeze-Dried Wild Blueberry Powder

Wild blueberry (WBB) powder can be added to the formulation of foods to encourage consumption of health-promoting polyphenolics, but the stability of polyphenolics throughout storage is important. We determined the stability of polyphenolics in five products (ice pop, oatmeal bar, graham cracker cookie, juice, and gummy product) prepared with WBB powder. Samples stored at 21 °C, 4.4 °C, or −20 °C (ice pops only) were analyzed at 0, 2, 4, 6, and 8 weeks for polyphenolic content and percent polymeric color. Total anthocyanins decreased over storage and storage temperatures in all products. However, the ice pop and the refrigerated juice both retained over 90% of their initial total anthocyanin content. The refrigerated oatmeal bar also showed good retention of anthocyanins (86%), but the gummy product retained only 43% and 51% when stored at 4.4 °C or 21 °C, respectively. The lower amount of polyphenolic compounds recovered in the gummies stored at 4.4 °C compared to 21 °C may be attributed to reduced extraction efficiency as a result of gel hardening at refrigerated temperature. Chlorogenic acid and flavonols were generally more stable than anthocyanins throughout storage.

Purple pigment from Peltogyne mexicana heartwood as a potential colorant for food

ABSTRACT

Peltogyne mexicana heartwood might be a novel purple pigment source. The results of the present study demonstrate that the purple pigment is an important source of phenolic compounds (698.22 ± 2.99 mg GAE/g) and flavonoids (48.01 ± 0.51 mg EPE/g). UV-Vis spectrum and color parameters (L* a* b*) showed that purple pigment has different shades of purple-red (H° value 19.32 ± 0.02 in methanol and 22.85 ± 0.01 in ethanol) depending on the solvent and the pH. Also, the purple pigment did not exhibit acute oral toxicity at a single dose (2000 mg/kg body weight). No mutagenicity was observed in the Ames test with three Salmonella typhimurium strains. The purple pigment exhibited considerable coloring properties with a wider range of citric acid-dependent color hues in gelatin (H° from 280.3 to 319.9 and from 68.0 to 88.1), and higher color intensity than commercial anthocyanin. Minor variations in the hue were found in yogurt, for purple pigment with H° values from 317.5 to 315.0, and commercial anthocyanin from 82.6 to 88.7 and 276.9 to 295.5. However, purple pigment required lower concentrations to achieve superior effects. For gelatin and yogurt samples, similar variations in the color parameters L*, a*, b*, and pigment degradation were observed for purple pigment and commercial anthocyanin in the stability assay.

GRAPHICAL ABSTRACT

Molecular interactions between 3,4-dihydroxyphenylglycol and pectin and antioxidant capacity of this complex in vitro

This study explored the interaction of pectin with 3,4-dihydroxyphenylglycol (DHPG), a potent phenolic antioxidant naturally found in olive fruit, via encapsulation into pectinate beads. MALDI TOF-TOF analysis supported the formation of complexes between DHPG and pectin. A combination of covalent bonds (ester bonds) and non-covalent interactions, mostly hydrogen bonding, were suggested as the cause of DHPG-pectin complex formation. Free radical scavenging assays confirmed that DHPG maintained its antioxidant activity after complexation and after a digestion simulated in vitro with gastric and intestinal fluids. Therefore, DHPG-pectin beads could reach the large intestine and contribute to a healthy antioxidant environment.

Encapsulation of purple corn and blueberry extracts in alginate-pectin hydrogel particles: Impact of processing and storage parameters on encapsulation efficiency

Purple corn (PC) and blueberry (BB) extracts were encapsulated in alginate-pectin hydrogel particles to protect anthocyanins (ACNs) from degradation. Combinations of alginate to pectin ratios at 82 to 18% and 43 to 57% and total gum concentrations (TGC) at 2.2% and 2.8% TGC were prepared to encapsulate both PC and BB ACN. The alginate-pectin hydrogel particles containing PC or BB extracts were produced by dripping solution into pH 1.2 buffer. Blueberry extract encapsulation efficiency was significantly higher than that of purple corn extract due to ACN chemical structure differences and the compatibility between the ACN structures and alginate-pectin hydrogel structure at the low pH environment. Effect of initial ACN concentration in droplets, particle shape, alginate to pectin ratio, TGC, ACN source, and curing bath conditions on encapsulation efficiency after curing (EE_m) was investigated. The initial ACN concentration and particle shape didn't influence the EE_m, while the alginate to pectin ratio, TGC, ACN source and the pH of the curing bath showed significant effect on the EE_m. The EE_m was improved from 26% to 65% for PC ACN and from 48% to 116% for BB ACN by augmenting curing bath with ACN at various concentrations. The ACN retention during storage (AR_s) in hydrogel particles stored in pH 3.0 buffer was improved at low temperature and high particle weight to solution volume ratio. Higher amount of ACN was retained in the hydrogel particles when spherical particles were used. Encapsulation in hydrogel particles significantly reduced the anthocyanin photodegradation upon exposure to fluorescence light. The degradation of ACN was described with a first-order kinetics with half-life values of 630 h for encapsulated PC ACN and 58 h for PC ACN aqueous solution. Hydrogel production and subsequent storage conditions can be optimized to increase the anthocyanin delivered to human body using the low pH beverages such as fruit juices as a delivery vehicle.

Polyphenol patterns to trace sweet (Prunus avium) and tart (Prunus cerasus) varieties in cherry jam

The aim of this work was to assess whether the characteristic polyphenol traits of cherry biotypes persisted in thermally processed cherry products, such as jam. Thus, the RP-HPLC-diode array detector profiles of both colorless polyphenols and anthocyanins from three cherry varieties (two sweet and one tart cherry) were compared with those of low-sugar jam sourced from the same cultivars. Individual components were characterized by mass spectrometry. The total phenolic and total anthocyanin content as well as the radical scavenging potential (residual 75-91, 88-91 and 73-75%, respectively) were only slightly reduced by deep thermal treatments. Apart from the interconversion among the isomers of chlorogenic acid, the profile of both colorless polyphenols and anthocyanins substantially survived the jam manufacturing under conventional temperature-time regimen (80 °C, 1 h). The species- and cultivar-specific polyphenol molecular asset, especially the anthocyanin pattern, has potential to be monitored for traceability purpose, aimed to the varietal assessment of cherry biotypes used for producing jam.

Complexation of hydroxytyrosol and 3,4-dihydroxyphenylglycol with pectin and their potential use for colon targeting

Hydroxytyrosol (HT) and 3,4-dihydroxyphenylglycol (DHPG) are two phenolic antioxidants naturally found in olive fruit with anti-inflammatory properties. This study explored the interaction of pectin with HT and DHPG via their encapsulation into pectinate beads. Purification by size exclusion chromatography, changes in the fluorescence spectrum of the HT and pectin, and MALDI TOF-TOF analysis suggested the existence of the phenol-pectin complexes. The entrapment efficiency, swelling properties, and in vitro release of HT and DHPG of the beads were studied. The results show that the beads can entrap the water soluble compounds HT and DHPG in sufficient amounts to reach the colon. The beads consisted of an important amount of pectin-bound HT or DHPG after two hours at gastric pH. This study highlights the potential use of HT-and DHPG-loaded pectinate gel beads for the colon-targeted delivery of these bioactive compounds to help prevent or relieve chronic inflammatory bowel disease.

Impact of a pectic polysaccharide on oenin copigmentation mechanism

Copigmentation plays an important role in the colors provided by anthocyanins. However, little attention has been paid to the interaction between anthocyanins and cell wall compounds (e.g. polysaccharides) and the impact of this interaction on anthocyanins color, a fundamental issue to be considered in industrial applications of these pigments as food colorants. The copigmentation binding constants (KCP) for the interaction between malvidin-3-O-glucoside and (+)-catechin in the presence of low methoxylated pectic polysaccharide were determined. The values obtained showed that in the presence of pectic polysaccharide the copigmentation binding constants decreased. These results probably suggest the occurrence of competition equilibrium in which the presence of pectin limited the association between catechin and oenin. (1)H NMR studies revealed that the dissociation constant determined for these complexes was very similar in absence and presence of 1.5g/L pectin with this polysaccharide apparently not affecting the strength of anthocyanin-catechin binding.

A study of anthocyanin self-association by NMR spectroscopy

Malvidin-3-O-coumaroylglucoside molecules self-associate, with this interaction occurring mainly by dispersive contacts (direct π–π stacking and van der Waals interactions).

Metabolite profiling of jaboticaba (Myrciaria cauliflora) and other dark-colored fruit juices

Many dark-colored fruit juices, rich in anthocyanins, are thought to be important for human health. Joboticaba (Myrciaria cauliflora) fruits, native to Brazil, have phenolics including anthocyanins and are processed into juice and other products. The phenolic constituents in the fruits of jaboticaba were studied by high-performance liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry. Twenty-two compounds were identified or tentatively determined by detailed analysis of their mass spectral fragmentation patterns; 11 compounds including 7 gallotannins, 2 ellagic acid derivatives, syringin, and its glucoside were detected for the first time in the fruit. The compositional differences among the fruit extracts and their commercial products were also compared by principal component analysis; two anthocyanins, delphinidin 3-O-glucoside and cyanidin-3-O-glucoside, as well as two depsides, jaboticabin and 2-O-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxyphenylacetic acid, present in the fruit extracts were not detected unexpectedly in commercial jaboticaba juice or jam. Therefore, the stability of anthocyanins in jaboticaba fresh fruits and products has been compared directly with that of other dark-colored fruit products made from blueberry and Concord grape, and the same trend of decreasing amounts of anthocyanins was observed in all tested products. The antioxidant activities (DPPH(•) and ABTS(•+)) of jaboticaba fresh fruit extract and commercial samples were also compared. Principal component analysis proved to be a useful way to discern changes between fresh and processed fruits. Jaboticaba is a promising fruit with antioxidant capacity similar to those of other so-called superfruits; however, during processing the levels of some of anthocyanins and other polyphenols decrease significantly, and therefore the capacity of these products to affect human health may vary significantly from that of the fresh fruit.

Tracking antioxidant properties and color changes in low-sugar bilberry jam as effect of processing, storage and pectin concentration

Background

Recently, an increased interest in the identification of valuable possibilities for preserving the antioxidant properties of products obtained by thermal processing of fruits rich in bioactive compounds can be noticed. In this regard, an extensive analysis is necessary in terms of thermal processed products behavior in relation to various factors. The purpose of the present study was to assess the effect which processing and storage at 20°C has on the antioxidant properties and color quality of low-sugar bilberry jam with different low-methoxyl pectin (LMP) concentrations.

Results

For all measured parameters, it should be noted that thermal processing induced significant alterations reported to the values registered for fresh fruit. Most important losses due to thermal processing were recorded for total monomeric anthocyanins (TMA) (81-84%), followed by L-ascorbic acid (L-AsAc) content (53-58%), total phenolics (TP) content (42-51%) and FRAP (ferric reducing antioxidant power) values (36-47%). Moreover, depreciation of the investigated compounds occurred during storage at 20°C. Jam storage for 7 months resulted in severe losses in TMA content in the range 58-72% from the value recorded one day after processing. This coincided with marked increases in polymeric color percent of these products after 7 months of storage. Also, bilberry jam storage for 7 months resulted in a decrease in L-AsAc content of 40-53% from the value recorded one day after processing, 41-57% in TP content and 33-46% from the value recorded one day after processing for FRAP values. By decreasing of LMP concentration in the jam recipe from 1 to 0.3% there has been an increase in losses of investigated compounds.

Conclusion

Overall, the results indicated that bilberry jams can also represent a good source of antioxidant compounds, although compared to the fruit, important losses seem to occur. Practical application of this work is that this kind of information will be very useful in optimizing the jam processing technology and storage conditions, in order to improve the quality of these products.

Stability of Pycnogenol® as an ingredient in fruit juices subjected to in vitro gastrointestinal digestion

BACKGROUND

The enrichment of fruit juices with concentrated polyphenolic extracts is an expedient strategy to compensate possible phenolic loss through gastrointestinal processing. Pycnogenol, a standardised procyanidin-rich extract from pine bark, has been proposed as a potential candidate for polyphenol enrichment of foods. In this study the effects of in vitro digestion on the phenolic profile of fruit juices enriched with Pycnogenol were investigated.

RESULTS

After in vitro digestion the level of detectable total phenolic compounds (expressed as gallic acid equivalent) was higher in both pineapple and red fruit juices enriched with Pycnogenol than in non-enriched commercial juices. Five phenolic monomeric compounds were identified by high-performance liquid chromatography, namely chlorogenic acid, caffeic acid, ferulic acid, gallic acid and taxifolin, the last two being predominant. In vitro digestion of both Pycnogenol-enriched pineapple and red fruit juices led to a significant (P < 0.05) increase in detectable chlorogenic and ferulic acids, indicating that hydrolysis of more complex molecules occurs. On the other hand, in vitro digestion of non-enriched juices was associated with a decrease in gallic and caffeic acids in pineapple juice and with a decrease in ferulic acid in red fruit juice. In no case did in vitro digestion increase the amount of detectable phenolic compounds in non-enriched juices.

CONCLUSION

The stability of Pycnogenol after in vitro gastrointestinal digestion makes it a good choice for phenolic enrichment of fruit juices.