Antioxidants and Bioactive Compounds in Food: Critical Review of Issues and Prospects.

This review paper gives an insight into the effective delivery mechanisms for health-promoting substances and highlights the challenges of using antioxidants and bioactives in foods. The selection criteria for choosing bioactives and their extraction in bioavailable form with their adequate incorporation techniques and delivery mechanisms are covered. Moreover, an overview of existing methods for determination of bioactivity is given. The importance of scientifically evaluating the effects of foods or food components on consumer health before making claims about the healthiness is aligned. Finally, a scientific perspective on how to respond to the booming demand for health-promoting products is given, and we acknowledge that despite the work done, there are still many challenges that need to be overcome.

Microencapsulation of Hibiscus sabdariffa L. Calyx Anthocyanins with Yeast Hulls.

Yeast hulls, due to their specific thin mannoprotein layer and high content of ß-glucan, constitute a promising material to stabilise the colour of anthocyanins. This study evaluates the potential of yeast hulls on the freeze-drying encapsulation of anthocyanins-rich extract from Hibiscus sabdariffa L. calyx with comparison to maltodextrin microcapsules. The moisture content (5.28-16.38%), water activity (< 0.039-0.307) and hygroscopicity (17.50-25.99 g/100 g) of obtained powders were evaluated. The stability of encapsulated anthocyanins, monitored through the total anthocyanin content, was evaluated with the pH differential method immediately after production and after a 10-week storage under different conditions of temperature (5 or 37 °C), humidity (45 or 85% RH), in presence or absence of light. The colour parameters (a, b*, L*, C*, H°, ΔE*) of powders were measured. The results indicated that yeast-hulls showed a good ability to protect anthocyanin against the influence of temperature, light, moisture compared to freeze-dried anthocyanins-rich extracts (p < 0.05). Yeast hulls protected anthocyanin better than maltodextrin under high humidity conditions (p < 0.05).

Aroma compounds production by solid state fermentation, importance of in situ gas-phase recovery systems.

Flavour and fragrance compounds are extremely important for food, feed, cosmetic and pharmaceutical industries. In the last decades, due to the consumer's increased trend towards natural products, a great interest in natural aroma compounds has arisen to the detriment of chemically synthesised ones. Recently, solid state fermentation (SSF) has been applied in the production of many metabolites. Aroma compounds can be produced by SSF with a higher yield compared to submerged fermentation (SmF). In SSF processes, aroma compounds can be produced in the solid matrix or in the headspace, but they can be lost or stripped when aeration is required. This review focuses on the production of aroma compounds by SSF processes with a special highlight on in situ systems to recover the volatiles released in the gaseous phase and stripped due to aeration. Following a brief presentation of specificities of SSF processes concerning the choice of microorganisms and the solid matrix used for the production of aroma compounds, bioreactor aspects, factors affecting production of aroma compounds and in situ gas phase aroma recovery systems in aerated SSF bioreactors are discussed.

Molecule structural factors influencing the loading of flavoring compounds in a natural-preformed capsule: Yeast cells.

Yeast cells are efficient microcapsules for the encapsulation of flavoring compounds. However, as they are preformed capsules, they have to be loaded with the active. Encapsulation efficiency is to a certain level correlated with LogP. In this study, the effect of structural factors on the encapsulation of amphiphilic flavors was investigated. Homological series of carboxylic acids, ethyl esters, lactones, alcohols and ketones were encapsulated into the yeast Yarrowia lipolytica. Although, in a single homological series, the length of the molecule and thus the LogP were correlated with encapsulation efficiency (EY%), big differences were observable between series. For instance, carboxylic acids and lactones exhibited EY% around 45%-55%, respectively, for compounds bigger than C8 and C6, respectively, whereas ethyl esters reached only about 15-20% for C10 compounds. For a group of various C6-compounds, EY% varied from 4% for hexanal to 45% for hexanoic acid although the LogP of the two compounds was almost similar at 1.9. In total our results point out the importance of the level of polarity and localization of the polar part of the compound in addition to the global hydrophobicity of the molecule. They will be of importance to optimize the encapsulation of mixtures of compounds.

Techniques to measure sorption and migration between small molecules and packaging. A critical review.

The mass transfer parameters diffusion and sorption in food and packaging or between them are the key parameters for assessing a food product's shelf-life in reference to consumer safety. This has become of paramount importance owing to the legislations set by the regulated markets. The technical capabilities that can be exploited for analyzing product-package interactions have been growing rapidly. Different techniques categorized according to the state of the diffusant (gas or liquid) in contact with the packaging material are emphasized in this review. Depending on the diffusant and on the analytical question under review, the different ways to study sorption and/or migration are presented and compared. Some examples have been suggested to reach the best possible choice, consisting of a single technique or a combination of different approaches.

Effect of relative humidity on carvacrol release and permeation properties of chitosan based films and coatings.

The influence of water vapour conditions on mass transport and barrier properties of chitosan based films and coatings were studied in relation to surface and structural properties. Water contact angles, material swelling, polymer degradation temperature, barrier properties (PO2, PCO2, WVP) and aroma diffusion coefficients were determined. The solvent nature and the presence of carvacrol influenced the surface and structural properties and then the barrier performance of activated chitosan films. Increasing RH from 0% to 100% led to a significant increase in material swelling. The plasticization effect of water was more pronounced at high humid environment, while at low RH the matrix plasticization was induced by carvacrol. The deposit of a thin chitosan layer on polyethylene decreased PO2 and PCO2 both in dry and humid conditions. The carvacrol release from the chitosan matrix was strongly influenced by RH. A temperature increase from 4 to 37°C also had an impact on carvacrol diffusivity but to a lesser extent than RH.

Carvacrol affects interfacial, structural and transfer properties of chitosan coatings applied onto polyethylene.

Different chitosan coating solutions were tested with the aim of investigating their adhesion and wettability onto polyethylene film to improve packaging performance and provide antimicrobial properties. Surface wetting kinetics was monitored by contact angle measurements. Addition of ethanol and carvacrol improved wettability and adhesion of the thin chitosan layer. Structure, water vapour, O2, CO2 and air permeabilities of self supported chitosan films and coated polyethylene were determined. The formation of a thin chitosan layer on polyethylene improved gas barrier properties decreasing the Permeability Coefficient for oxygen and carbon dioxide ( [Formula: see text] , [Formula: see text] ) from 100 to 10,000 times. Presence of carvacrol in the chitosan coating layer increased [Formula: see text] , [Formula: see text] and Pair by a factor of ten. Moreover, it influenced film microstructure. However chitosan was shown to be good gas barrier film in the dry state.

Aroma behaviour during steam cooking within a potato starch-based model matrix.

To help understand the organoleptic qualities of steam cooked foods, the kinetics of aroma release during cooking in a potato starch based model matrix was studied. Behaviour of components having a major impact in potato flavour were studied using solid phase micro extraction-gas chromatography (SPME-GC). Evolution of microstructure of potato starch model-matrix during steam cooking process was analyzed using environmental scanning electron microscopy (ESEM). Both aroma compounds that are naturally present in starch matrix and those that were added were analyzed. Both the aroma compounds naturally presented and those added had different behaviour depending on their physico-chemical properties (hydrophobicity, saturation vapour pressure, molecular weight, etc.). The physical state of potato starch influences of the retention of aromatized matrix with Starch gelatinization appearing to be the major phenomenon influencing aroma release.

Release behavior and stability of encapsulated D-limonene from emulsion-based edible films.

Edible films may act as carriers of active molecules, such as flavors. This possibility confers to them the status of active packaging. Two different film-forming biopolymers, gluten and ι-carrageenans, have been compared. D-Limonene was added to the two film formulations, and its release kinetics from emulsion-based edible films was assessed with HS-SPME. Results obtained for edible films were compared with D-limonene released from the fatty matrix called Grindsted Barrier System 2000 (GBS). Comparing ι-carrageenans with gluten-emulsified film, the latter showed more interesting encapsulating properties: in fact, D-limonene was retained by gluten film during the process needed for film preparation, and it was released gradually during analysis time. D-Limonene did not show great affinity to ι-carrageenans film, maybe due to high aroma compound hydrophobicity. Carvone release from the three different matrices was also measured to verify the effect of oxygen barrier performances of edible films to prevent D-limonene oxidation. Further investigations were carried out by FT-IR and liquid permeability measurements. Gluten film seemed to better protect D-limonene from oxidation. Gluten-based edible films represent an interesting opportunity as active packaging: they could retain and release aroma compounds gradually, showing different mechanical and nutritional properties from those of lipid-based ingredients.

Interaction Mechanisms between guaiacols and lignin: the conjugated double bond makes the difference.

Lignin is considered to be responsible for a selective sorption of phenolic compounds on wood. In order to investigate the mechanisms involved, two similar guaiacol compounds--only differing by the nature of the para side chain--were adsorbed on oak wood extracted lignin. Vapor sorption-desorption isotherms indicated that about 3.5 wt % of 4-vinylguaiacol is adsorbed near saturation whereas it is only 0.8% for 4-ethylguaiacol. For both compounds, the isotherms displayed a hysteresis though significantly greater for 4-vinylguaiacol. Analyses of the hydroxyl stretching region of FTIR spectra of the lignin/4-ethylguaiacol and lignin/4-vinylguaiacol complexes indicated that physisorption via hydrogen bonds occurs for both sorbates with lignin phenolic hydroxyl groups but which would be more condensed for the former than for the latter. According to NMR spectra, these phenolic hydroxyl groups correspond to non-etherified guaiacyl subunits. In contrast with other para substituents, the conjugated vinyl bond favors not only physisorption but also chemisorption as witnessed by the fact that upon desorption in the vapor phase, even after pumping under dynamic vacuum for several days, about 1 wt % of 4-vinylguaiacol remains adsorbed onto lignin.

Liquid and vapour water transfer through whey protein/lipid emulsion films.

BACKGROUND: Edible films and coatings based on protein/lipid combinations are among the new products being developed in order to reduce the use of plastic packaging polymers for food applications. This study was conducted to determine the effect of rapeseed oil on selected physicochemical properties of cast whey protein films. RESULTS: Films were cast from heated (80 degrees C for 30 min) aqueous solutions of whey protein isolate (WPI, 100 g kg(-1) of water) containing glycerol (50 g kg(-1) of WPI) as a plasticiser and different levels of added rapeseed oil (0, 1, 2, 3 and 4% w/w of WPI). Measurements of film microstructure, laser light-scattering granulometry, differential scanning calorimetry, wetting properties and water vapour permeability (WVP) were made. The emulsion structure in the film suspension changed significantly during drying, with oil creaming and coalescence occurring. Increasing oil concentration led to a 2.5-fold increase in surface hydrophobicity and decreases in WVP and denaturation temperature (T(max)). CONCLUSION: Film structure and surface properties explain the moisture absorption and film swelling as a function of moisture level and time and consequently the WVP behaviour. Small amounts of rapeseed oil favourably affect the WVP of WPI films, particularly at higher humidities.

Wine oxidation and the role of cork.

The present review aims to show the state of the art of oxidation mechanisms occurring especially in white wines by taking into account knowledge from different fields in relation to the subject. It is therefore divided into three main parts. First, the mechanisms of oxidation relevant to white wine are discussed in the light of recent scientific literature. Next, the phenomenon of oxygen solubility in wine during the winemaking process, and in particular during bottling is stated theoretically as well as practically. Finally, the aspect of wine conservation after bottling is examined with respect to mass transfers which may occur through the closure, with a special emphasis on cork. Currently, specific physico-chemical properties still make cork closures the most important closure type used for the wine market, and especially for high quality wines. This final section will also include a review of studies performed on this subject, which have been analyzed in detail from a theoretical mass transfer point of view, in order to assess the extent to which the proposed scientific tools and the observed tendencies are relevant to progress in the understanding of the impact of this parameter on the behavior of a wine.

The chemodiversity of wines can reveal a metabologeography expression of cooperage oak wood.

Wine chemical compositions, which result from a complex interplay between environmental factors, genetic factors, and viticultural practices, have mostly been studied using targeted analyses of selected families of metabolites. Detailed studies have particularly concerned volatile and polyphenolic compounds because of their acknowledged roles in the organoleptic and therapeutic properties. However, we show that an unprecedented chemical diversity of wine composition can be unraveled through a nontargeted approach by ultrahigh-resolution mass spectrometry, which provides an instantaneous image of complex interacting processes, not easily or possibly resolvable into their unambiguous individual contributions. In particular, the statistical analysis of a series of barrel-aged wines revealed that 10-year-old wines still express a metabologeographic signature of the forest location where oaks of the barrel in which they were aged have grown.

Expressing forest origins in the chemical composition of cooperage oak woods and corresponding wines by using FTICR-MS.

A non-targeted, ultra-high-resolution mass spectrometric, direct analysis of oak-wood extracts from two species (Quercus robur L. and Quercus petraea Liebl.) from three French forests, and of a wine aged in barrels derived therefrom has been performed to identify families of metabolites that could discriminate both the species and the geographical origin of woods. From 12 T ultra-high-resolution Fourier transform ion cyclotron resonance mass spectra of wood extracts, hundreds of mass signals were identified as possible significant biomarkers of the two species, with phenolic and carbohydrate moieties leading the differentiation between Q. robur and Q. petraea, respectively, as corroborated by both FTMS and NMR data. For the first time, it is shown that oak woods can also be discriminated on the basis of hundreds of forest-related compounds, and particular emphasis is put on sessile oaks from the Tronçais forest, for which sugars are significantly discriminant. Despite the higher complexity and diversity of wine metabolites, forest-related compounds can also be detected in wines aged in related barrels. It is only by using these non-targeted analyses that such innovative results, which reveal specific chemodiversities of natural materials, can be obtained.

Role of wood macromolecules on selective sorption of phenolic compounds by wood.

Wood is a complex structure of various macromolecules, mainly cellulose, hemicellulose, and lignin. Although the sorption process of some organic compounds by wood has been elucidated, the relative contribution of its different fractions in the sorption mechanism is not clearly determined. Certain works predict the amount of organic compounds sorbed on wood as a direct relationship to its lignin fraction. All wood macromolecules, however, seem to have the capacity to sorb organic compounds. Sorption of phenolic compounds on individual wood macromolecules has been studied and compared to that on wood. Wood-water partition coefficients ( K wood) for phenolic volatiles and their sorption rates in the presence of lignin display a linear relationship. Results show that cellulose and hemicellulose sorb all phenolic compounds without apparent distinction, whereas lignin is a selective sorbent of these compounds. Sorbant availability and sorbate chemical structure seem to be the key factors governing the sorption mechanism. Sorption kinetics study gives apparent diffusion coefficient values of aroma compounds, bringing new kinetic data for understanding the ternary system of wood, hydroalcoholic solution, and phenolic compounds.

Aroma barrier properties of sodium caseinate-based films.

The mass transport of six different aroma compounds (ethyl acetate, ethyl butyrate, ethyl hexanoate, 2-hexanone, 1-hexanol, and cis-3-hexenol) through sodium caseinate-based films with different oleic acid (OA)/beeswax (BW) ratio has been studied. OA is less efficient than BW in reducing aroma permeability, which can be attributed to its greater polarity. Control film (without lipid) and films prepared with 0:100 OA/BW ratio show the lowest permeability. OA involves a decrease in aroma barrier properties of the sodium caseinate-based films due to its plasticization ability. Preferential sorption and diffusion occurs through OA instead of caseinate matrix and/or BW. The efficiency of sodium caseinate-based films to retain or limit aroma compound transfers depend on the affinity of the volatile compound to the films, which relates physicochemical interaction between volatile compound and film. Specific interactions (aroma compound-hydrocolloid and aroma compound-lipid) induce structural changes during mass transfer.

Protection of active aroma compound against moisture and oxygen by encapsulation in biopolymeric emulsion-based edible films.

Edible films made of iota-carrageenans display interesting advantages: good mechanical properties, stabilization of emulsions, and reduction of oxygen transfers. Moreover, the addition of lipids to iota-carrageenan-based films to form emulsified films decreases the transfer of water vapor and can be considered to encapsulate active molecules as flavors. The aim of this study was to better understand the influence of the composition and the structure of the carrageenan-based film matrices on its barrier properties and thus on its capacity to encapsulate and to protect active substances encapsulated. Granulometry, differential scanning calorimetry, and Fourier transform infrared spectroscopy characterizations of films with or without flavor and/or fat showed that the flavor compound modifies the film structure because of interactions with the iota-carrageenan chains. The study of the water vapor permeability (WVP), realized at 25 and 35 degrees C and for three relative humidity differentials (30-100%, 30-84%, 30-75%), showed that the flavor compound increases significantly the WVP, especially for the weaker gradients, but has no effect on the oxygen permeability. This study brings new understanding of the role of carrageenan as a film matrix and on its capacity to protect encapsulated flavors.

Different sorption behaviors for wine polyphenols in contact with oak wood.

The evolution of polyphenols of enological interest- monomeric anthocyanins, (+)-catechin, (-)-epicatechin, gallic acid, and trans-resveratrol-in the presence of oak wood was investigated in aging-model conditions. Disappearance kinetics showed that, except for gallic acid, all of the wine polyphenols tend to disappear from the model wine in presence of oak wood, to reach an equilibrium after 20 days of contact. At equilibrium, the higher disappearance rates were obtained for monomeric anthocyanins and trans-resveratrol with values of 20 and 50%, respectively. For monomeric anthocyanins, the rate of disappearance seemed to be independent of their nature. In order to evaluate the contribution of sorption to oak wood in the disappearance phenomena, sorption kinetics were determined for trans-resveratrol and malvidin-3-glucoside through the extraction and the quantification of the fraction sorbed to wood. These curves showed that the wood intake of trans-resveratrol and malvidin-3-glucoside followed a two-step behavior, with a higher rate during the first 2 days, likely due to a surface sorption mechanism, and then a slower rate to reach the equilibrium, which could be related to a diffusion mechanism. The comparison of disappeared and sorbed amounts at equilibrium showed that a minor part of the disappeared monomeric anthocyanins were sorbed by wood. In contrast, half of the concentration decrease of trans-resveratrol in wine finds its origin in a sorption mechanism by oak wood. Results in real wine show similar sorption kinetics.

Tracer aroma compound transfer from a solid and complex-flavored food matrix packed in treated papers or plastic packaging film.

The objective of this work was to study the transfer of four aroma compounds (ethyl butyrate, ethyl hexanoate, cis-3-hexenol, and benzaldehyde) from a solid and complex-flavored food matrix (sponge cake) toward and through packaging films placed in indirect contact during storage in accelerated aging conditions (38 degrees C and 86% relative humidity gradient). The efficiency of treated papers relative to that of standard paper and plastic as barrier was tested. Before storage, aroma compound volatility in the sponge cake was measured, and similar values were found between aroma compounds, due to the fat content of the sponge cake. Whatever the aroma compound, permeability values during storage were similar for the same packaging film. The plastic film was the highest barrier, whereas calendering and coating treatments applied to treated papers decreased effectively their permeability. An opposite trend was observed for aroma compound sorption into packaging films during storage.

Importance of surface tension characterization for food, pharmaceutical and packaging products: a review.

This article reviews the various theoretical approaches that have been developed for determination of the surface tension of solids, and the applications to food industrial products. The surface tension of a solid is a characteristic of surface properties and interfacial interactions such as adsorption, wetting or adhesion. The knowledge of surface tension is thus of great interest for every domain involved in understanding these mechanisms, which recover a lot of industrial investigations. Indeed, it is the case for the packaging industry, the food materials science, the biomedical applications and the pharmaceutical products, cleaning, adhesive technology, painting, coating and more generally all fields in relation with wettability of their systems. There is however no direct method for measurements of surface tension of solids, except the contact angle measurements combined with an appropriate theoretical approach are indirect methods for estimation of surface tension of solids. Moreover, since the publication by Young (1805) who developed the basis of the theory of contact angle some two hundred years ago, measurements and interpretations are still discussed in scientific literature, pointing out the need to better understand the fundamental mechanisms of solid-liquid interfacial interactions. Applications of surface tension characterization in the field of food materials science are detailed, especially for packaging and coating applications, which recover different actual orientations in order to improve process and quality.