RESUMEN

A chitosan-glucose derivative (ChG) with lower antimicrobial activity against whey native probiotic yeast K. marxianus VM004 was synthesized by the Maillard reaction. The ChG derivative was characterized by FT-IR, 1H NMR, and SLS to determine the structure, deacetylation degree (DD), and molecular weight (Mw). In addition, we evaluated the antioxidant, cytotoxic, and antimicrobial activities of ChG. ChG was then used for microencapsulation of K. marxianus VM004 by spray drying. The microcapsules were characterized by evaluating their encapsulation yield, encapsulation efficiency, morphology, tolerance to the gastrointestinal tract, and viability during storage. The results indicated that a non-cytotoxic product with lower MW and DD and higher antioxidant activity than native chitosan was obtained by the Maillard reaction. The yeast ChG microcapsules exhibited an encapsulation efficiency >57 %, improved resistance to gastrointestinal conditions, and enhanced stability during storage. These results demonstrate that ChG may be a promising wall material for the microencapsulation of probiotic yeasts.

Asunto(s)

RESUMEN

Bacteriocins from Gram-positive bacteria have been proposed as natural food preservative and there is a need for large-scale production for commercial purposes. The aim of the present work is to evaluate whey, a cheese industrial by-product, for the production and microencapsulation of enterocin CRL35. Whey proved to be a promising basal medium for bacterial growth although the bacteriocin production was quite low. However, it could be much favored with the addition of yeast extract at concentrations as low as 0.5%. Besides improving bacteriocin production, this peptide was successfully microencapsulated by spray drying using whey protein concentrate and a chitosan derivative as wall materials. Microcapsules averaging 10 ± 5 µm diameter were obtained, with good structural integrity and high antimicrobial activity with a stability of at least 12 weeks at 4°C. In summary, sustainable bacteriocin production and microencapsulation was achieved recycling whey or its derivatives. In addition, the formulation owns high antimicrobial activity with a long shelf life. The development of a food preservative may represent a green solution for handling whey.

Asunto(s)

RESUMEN

The agro-industry produces numerous byproducts that are currently underused, and its waste contributes to environmental pollution. These byproducts represent an important and economical source of bioactive ingredients, which can promote the sustainable development of high-value-added functional foods. In this context, micro- and nanoencapsulation systems allow for the incorporation and stabilization of the bioactive agents in foods. This perspective will review recent advances in the use of agro-industrial byproducts as a source of bioactive agents. In addition, the latest advances in micro- and nanoencapsulation to improve the stability, solubility, and bioaccessibility of bioactive agents as functional food ingredients are exposed.

Asunto(s)

RESUMEN

We used water-soluble Chitosan obtained by Maillard reaction with glucosamine to microencapsulate soy genistein (Ge) and preserve its biological activity for oral administration. Release of Ge was pH dependent with a super Case II mechanism at pH 1.2 and an anomalous transport with non-Fickian kinetics at pH 6.8. Microencapsulated Ge retained its antioxidant properties in vitro and its daily administration to mice attenuated clinical signs of acute colitis, limited inflammatory reaction and reduced oxidative stress and tissue injury as well. Remarkably, after feeding microencapsulated Ge the production of IL-10 in colonic tissue was restored to levels of untreated controls. According to statistical multivariate analysis, this cytokine was the parameter with the highest influence on the inflammatory/oxidative status. Microencapsulation of Ge with derivatized Chitosan becomes an interesting alternative to develop therapeutic approaches for oxidative inflammatory diseases; our findings suggest that the soy isoflavone could be incorporated into any functional food for application in intestinal inflammation.

Asunto(s)

Asunto(s)

RESUMEN

New water-soluble chitosan derivatives (WSCh) were obtained by Maillard reaction (MR) between glucosamine (GA) with both low and medium molecular weight chitosans (Ch). The WSCh showed larger solubility than the respective Ch, while their deacetylation degree (DD) decreased by approximately 12%. Infrared spectroscopy experiments of WSCh confirmed the formation of imine bonds after MR with intensified pyranose structure, and sugar molecules as polymer branches. However, a 6-times reduction of the molecular weight of WSCh was measured, indicating the breakdown of the polysaccharide chain during the MR. The polysaccharides quenched singlet molecular oxygen (1O2), with rate quenching constants correlating with the DD value of the samples, suggesting the important role of amino groups (-NH2) in the deactivation of 1O2. Additionally, all polysaccharides presented antimicrobial activity against pathogenic bacteria, e.g. Staphylococcus aureus, Escherichia coli, Salmonella sp., Enterococcus faecalis and Listeria ivanovii, as tested by their minimum inhibitory concentration (MIC). This way we obtained new water-soluble polysaccharides, with similar functional properties to those presented by native Ch, enhancing its potential application as carrier material for bioactive compounds.

Asunto(s)

RESUMEN

The known O2((1)∆g)-sensitizer system Chitosan bounded Rose Bengal (CH-RB), with Rose Bengal (RB) immobilized by irreversible covalent bonding to the polymer Chitosan (CH), soluble in aquous acidic medium, was employed in the photodegradation of three tri-hydroxy benzene water-contaminants (THBs). The system sensitizes the O2((1)∆g)-mediated photodegradation of THBs by a process kinetically favored, as compared to that employing free RB dissolved in the same solvent. Additionally the free xanthene dye, degradable by O2((1)∆g) through self-sensitization upon prolonged light-exposure, is considerably protected when bonded to CH-polymer. The polymeric sensitizer, totally insoluble in neutral medium, can be removed from the solution after the photodegradative cycle by precipitation through a simple pH change. This fact constitutes an interesting aspect in the context of photoremediation of confined polluted waters. In other words, the sensitizing system could be useful for avoiding to dissolve dyestuffs in the polluted waters, in order to act as conventional sunlight-absorbing dye-sensitizers. In parallel the interaction CH-O2((1)∆g) in acidic solution was evaluated. The polymer quenches the oxidative species with a rate constant 2.4 × 10(8) M(-1) s(-1) being the process mostly attributable to a physical interaction. This fact promotes the photoprotection of the bonded dye in the CH-RB polymer.

Asunto(s)

RESUMEN

Microcapsules (MC) made with gum arabic (GA) as shell material without and with ß-carotene (ßc) as core material were prepared by the spray-drying technique. The effect of these MC on the photodegradation of riboflavin (Rf) in whole milk by fluorescent daylight lamp irradiation was evaluated at a storage temperature of 4°C. The additions of 1.37mg/mL of MC without ßc (MC-GA) and with 0.54µg/mL of ßc (MC-ßc-GA) decreased the apparent first-order rate constant of Rf photodegradation by approximately 26 and 30%, respectively. A systematic kinetic and mechanistic analysis of the results indicates that the global protective effect of the MC is mainly due to the combination of quenching of the electronically excited triplet state of Rf and scavenging of the photogenerated reactive oxygen species, such as singlet molecular oxygen, superoxide radical anion and hydroxyl radical. A minor contribution to the photoprotective effect can be also associated with the inner-filter effect exerted by the MC, which partially blocks the direct excitation of Rf. These results allow us to conclude that photodegradation of Rf in milk can be considerably reduced by the addition of small amounts of MC, avoiding large losses in the nutritional value of milk.

Asunto(s)

RESUMEN

Microcapsules of gum arabic or maltodextrin 20DE containing antioxidant molecules (AOx), for example, carotenoids and tocopherol derivatives, were prepared by the spray-drying technique. The properties of these microcapsules were evaluated by several techniques, such as dynamic light scattering, scanning electronic microscopy, and steady-state and time-resolved fluorescence spectroscopy of microencapsulated pyrene. The quenching of photochemically generated singlet molecular oxygen ((1)O(2)) by the AOx in homogeneous solvents as well as in microcapsule solutions was evaluated using time-resolved phosphorescence detection of (1)O(2). The quenching rate constant of the process, k(Q)(AOx), was strongly dependent on the type of the AOx. These results are explained by compartmentalization effects of the AOx in the core of the microcapsules and the accessibility of (1)O(2). The contribution of the biopolymer as quencher of (1)O(2) was also investigated. The present results can be applied to the design of edible antioxidant microcapsules within the food and cosmetic industries.

Asunto(s)

RESUMEN

Riboflavin (Rf)-mediated photosensitized degradation of vitamins A and D3 in skimmed milk under illumination with a white fluorescence lamp was studied by using the HPLC technique. The photosensitized degradation of both vitamins followed first-order kinetics, and the temperature effect on the observed photodegradation rate constant allowed the determination of the activation energy Ea as being 4 and 16 kcal/mol for vitamins A and D3, respectively. The addition of lycopene microencapsulated by spray-drying with a gum arabic-sucrose (8:2) mixture (MIC) produced a reduction of ca. 45% in the photosensitized degradation rate of both vitamins. Front-face fluorescence experiments showed the same photoprotection factor in the degradation of Rf itself, indicating that the photodegradation mechanism involved Rf-mediated reactive species, such as the excited triplet state of Rf, 3Rf*, and/or singlet molecular oxygen, 1O2. The interaction of both 3Rf* and 1O2 with MIC was evaluated in aqueous solutions by using laser-induced time-resolved absorption or emission spectroscopy, and the contribution of an inner-filter effect in the presence of MIC in skimmed milk was evaluated by diffuse reflectance spectroscopy. The main operating mechanism of photoprotection is due to the deactivation of 3Rf* by the proteic component of gum arabic; thus, gum arabic based microcapsules could be used to improve the photostability of milk during its storage and/or processing under light.

Asunto(s)

RESUMEN

The photosensitized isomerization reaction of the natural cis carotenoid bixin (methyl hydrogen 9'-cis-6, 6'-diapocarotene-6, 6'-dioate) with rose bengal or methylene blue as the sensitizer in acetonitrile/methanol (1:1) solution was studied using UV-vis spectroscopy, high-performance liquid chromatography (HPLC), and time-resolved spectroscopic techniques, such as laser-flash photolysis and singlet oxygen phosphorescence detection. In both N(2)- and air-saturated solutions, the main product formed was all-trans-bixin. The observed isomerization rate constants, k(obs), decreased in the presence of air or with increase in the bixin concentration, suggesting the participation of the excited triplet state of bixin, (3)Bix, as precursor of the cis--> trans process. On the other hand, bixin solutions in the absence of sensitizer and/or light did not degrade, indicating that the ground state of bixin is stable to thermal isomerization at room temperature. Time-resolved spectroscopic experiments confirmed the formation of the excited triplet state of bixin and its deactivation by ground state bixin and molecular oxygen quenching processes. The primary isomerization products only degraded in the presence of air and under prolonged illumination conditions, probably due to the formation of oxidation products by reaction with singlet molecular oxygen. An energy-transfer mechanism was used to explain the observed results for the bixin transformations, and the consequences for food color are discussed.

Asunto(s)

RESUMEN

The influence of the medium heterogeneity upon the bimolecular rate constants for the physical quenching, kq, and chemical quenching, kr, of singlet molecular oxygen O2(1deltag) by seven natural and three synthetic carotenoids (CAR) with different substituent patterns was studied in a reverse micelle system of sodium bis(2-ethylhexyl)sulfosuccinate, hexane and water. Because O2(1deltag) was generated inside the water pools of the reverse micelles by photosensitization of the water-soluble dye rose bengal and the CAR are mainly located in the external hexane pseudophase, the quenching process was interpreted using a pseudophase model for the partition of 02(1deltag) between the water pools and the organic pseudophases. The kq values were mainly dependent on the extent of the double-bond conjugation of the CAR, as demonstrated by a good empirical relationship between log(k(q)) and the energy E(S) of the longest wavelength transition pi-->pi* of the CAR. In contrast, the kr values were almost independent of the extent of the double-bond-conjugated system and about four orders of magnitude lower than kq. However, in all cases, CAR photobleaching was observed with the formation of various oxidation products, depending on the photosensitization time. Chromatographic and spectroscopic product analysis for the reaction products of beta-carotene with O2(1deltag) indicated the formation of the beta-carotene-5,8-endoperoxide as the primary oxidation product.

Asunto(s)

RESUMEN

The carotenoid composition of butternut squash (Cucurbita moschata) cultivated in the province of Santiago del Estero, Argentina, was determined. The main carotenoids isolated were identified as beta-carotene (beta,beta-carotene), alpha-carotene (beta,epsilon-carotene), and lutein (beta,epsilon-carotene-3,3'-diol) and the minor carotenoids, as phytofluene (7,8,11,12,7',8'-hexahydro-psi,psi-carotene), zeta-carotene (7,8,7',8'-tetrahydro-psi,psi-carotene), neurosporene (7,8-dihydro-psi,psi-carotene), violaxanthin (5,6,5',6'- diepoxy-5,6,5',6'-tetrahydro-beta,beta-carotene-3,3'-diol) and neoxanthin (5,6-epoxy-6,7-didehydro-5,6,5',6'-tetrahydro-beta,beta- carotene-3,5,3'-triol). In some samples, 5,6,5',6'-beta-carotene diepoxide, (5,6,5',6'-diepoxy-5,6,5',6'-tetrahydro-beta,beta-carotene) and flavoxanthin (5,8-epoxy-5,8-dihydro-beta,epsilon-carotene-3,3'-diol) were detected. The presence of cis-isomers of beta,beta-carotene was also detected by HPLC. The vitamin A value obtained was 432 micrograms RE/100 g fresh sample, which indicates that this vegetable is an important source of provitamin A.

Asunto(s)