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In this study, we evaluated whether quantitative PCR (qPCR) and reverse transcription-qPCR (RT-qPCR) results could be affected by extracellular (free) DNA or RNA, respectively, obtained either from isolated bacteria or from fermented dairy foods manufactured with these microorganisms. These experimental set-ups involved two starter lactic acid bacteria (SLAB), Streptococcus thermophilus and Lactococcus lactis, as models across their most common technological environments: yoghurt, milk and cheese. The presence of free DNA modified qPCR results in levels sufficient to bias SLAB determinations, indicating that DNA may be a poor measure of cellular integrity. Furthermore, we showed for the first time that an order of magnitude more of free RNA than of DNA had to be used to modify RT-qPCR results. Importantly, the interference produced by free DNA and RNA was maintained across all the dairy matrices evaluated, independently of the SLAB and of the source of nucleic acids used, in both negative and positive samples. This study suggests that, contrary to DNA molecules, mRNA from dead microorganisms or from other extracellular sources may not be a determinant factor in skewing molecular quantifications. Therefore, our results support the potential use of mRNA as a molecular signature of cell integrity in dairy matrices. Fil: Pega, Juan Franco. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rizzo, Sergio Anibal. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Rossetti, Luciana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Pérez, Carolina Daiana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Díaz, G.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Descalzo, Adriana Maria. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Centre de Coopération Internationale en Recherche Agronomique pour le Développerment; Francia Fil: Nanni, Mariana Sandra. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

A useful pectin-enriched fraction (PEF) extracted through high-power-ultrasound (HPUS) pretreatment and sodium carbonate was efficiently obtained from discarded carrots. Formerly, the effect of HPUS-power intensity and time (A: 40 min-2.08 W/cm 2 ; B-E: 5–20 min ≈ 10 W/cm 2 ) on carrot powder (CP) used for PEF-isolation, was investigated. Reducing carbohydrates-, cell-wall neutral sugars- (NS), uronic acids- (UA) of pectins, and protein releases increased with HPUS-energy. CP had antioxidant capacity, containing α- and β-carotene, lutein, α-tocopherol. Only HPUS B-E treatments (≈10 W/cm 2 ) were capable to produce matrix disruption, promoting polymers’ release. CP pretreated through selected E-treatment (20 min; ≈10 W/cm 2 ) followed by 0.1M-Na 2 CO 3 (1 h-stirring) extracted the whole pectin content of CP (UA = 14.0%). PEFs were orange, with co-extracted antioxidants. More substituted (1.27 NS/UA ratio) three lower molecular weights’ components of HPUS-PEF produced higher Newtonian viscosity before shear-thinning, and calcium-crosslinked gels with lower elastic modulus (G’ = 12Pa). Sustainable HPUS/Na 2 CO 3 method isolated efficiently an antioxidants-carrying PEF useful as functional food additive. Fil: Idrovo Encalada, Alondra Mariela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Pérez, Carolina Daiana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Alzate Calderón, Paola Carolina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Zukowski, Enzo Fernando. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Gerschenson, Lia Noemi. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Rojas, Ana Maria Luisa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Fissore, Eliana Noemi. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina

Carrot residues were upgraded as pectin-enriched fractions (PEFs) useful for functional food formulation due to co-extracted antioxidants (α- and β-carotenes, lutein, α-tocopherol), and gelling effect. High power ultrasound (US)-enzyme assisted extraction was applied for efficiency and sustainability. Carrot powder (CP) in citrate-buffer (pH 5.20) was submitted to US-pretreatment (12.27 W/cm 2 : 20 kHz, 80% amplitude, 20 min) and a subsequent digestion (5 h-40 °C) without or with hemicellulase or cellulase. US-hemicellulase led to the highest PEF yield (27.1%), and extracted almost the whole pectin content of CP. US-pretreatment increased the extraction yield of all PEFs, but the existence of an additional positive effect of the following step depended on the enzyme used. PEFs contained 40–47% of UA with low DM (24–49.9%), and co-extracted antioxidants. US decreased the antioxidant contents, DM, and molecular weight, but allowed obtaining calcium crosslinked true gels, also with higher elastic modulus than non-US-extracted PEFs, being promising as food additives. Fil: Idrovo Encalada, Alondra Mariela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Pérez, Carolina Daiana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Flores, Silvia Karina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Rossetti, Luciana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Fissore, Eliana Noemi. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Rojas, Ana Maria Luisa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina

Misshapen carrots were upgraded as orange-colored pectin-enriched fractions (PEFs) useful as gelling agents and containing α- and β-carotenes, lutein, and α-tocopherol, by applying a green process consisting of an ultrasound (US) pretreatment (12.27 W/cm2 power intensity) followed by stirring in citrate buffer (pH 5.20) either without or with an industrial enzyme (fungal and bacterial hemicellulases, and cellulase) commercialized as baking improvers. PEFs showed uronic acid (UA) contents between 39 and 51% with low degree of methylesterification (DM, 37.2–48%), 11–22% degree of acetylation (DA), and a common molecular weight of 121,000–138,000 Da. The protein contents were 9.6–17.8%. Only the use of fungal hemicellulase produced per se higher yield of the PEF obtained (10.4%), in comparison to the non-US pretreated citrate buffer extracted pectins (6.9%). The US-pretreatment was the step that decisively produced high extractive yields (≈20%), while there was not additional contribution of industrial enzymes. However, enzymes permitted to obtain PEFs with different gel characteristics. US-pretreated PEFs at 2.00% w/v in water showed the best rheological performances, forming calcium-crosslinked true gels, more structured and with higher elastic (G’) modulus than non-US pretreated isolated fractions, one of which did not gel, being then useful as functional additives for food formulation. Fil: Idrovo Encalada, Alondra Mariela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Pérez, Carolina Daiana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gerschenson, Lia Noemi. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Rojas, Ana Maria Luisa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina Fil: Fissore, Eliana Noemi. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias. Instituto de Tecnología de Alimentos y Procesos Químicos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Tecnología de Alimentos y Procesos Químicos; Argentina

The main goal of the present work was to determine the oxidative stability of Stuart pecans stored at different temperatures throughout 300 days (approximately 10 months post-harvest). In-shell pecans were stored at 2 °C and 20 °C at 65 % relative humidity and the oxidative stability was evaluated at 60 days intervals. At 20 °C, lipid oxidation markers were significantly higher than at 2 °C. Kinetic of oxidation showed significant changes after 210 days of storage with hexanal and pentanal levels 10-fold higher at 20 °C than at 2 °C, leading to development of rancid and bitter taste with the significant loss of typical flavour and sweetness. Low storage temperature helped lower the levels of oxidative markers but did not avoid the rise of oxidation. Fatty acids and α-tocopherol did not change throughout storage, but γ- tocopherol showed a 12 % and 24 % decrease when pecans were stored for 300 days at 2 °C and 20 °C respectively. The Principal component analysis showed a clear correlation between hexanal and pentanal and the appearance of bitter and rancid taste in nuts along with the storage time. Aldehydes resulted in a suitable non-destructive marker of pecans stability and quality. Therefore, refrigeration of in-shell pecans reduced the oxidation and its sensory consequences.

The quality of functional food products designed for the prevention of degenerative diseases can be affected by the incorporation of bioactive compounds. In many types of cheese, the performance of starter microorganisms is critical for optimal elaboration and for providing potential probiotic benefits. Phytosterols are plant lipophilic triterpenes that have been used for the design of functional dairy products because of their ability to lower serum cholesterol levels in humans. However, their effect on the starter culture behavior during cheesemaking has not yet been studied. Here, we followed DNA and RNA kinetics of the bacterium Streptococcus thermophilus, an extensively used dairy starter with probiotic potential, during industrial production of a functional, semi-soft, reduced-fat cheese containing phytosterol esters and alpha-tocopherol as bioactive compounds. For this purpose, real-time quantitative PCR (qPCR) and reverse transcription-qPCR (RT-qPCR) assays were optimized and applied to samples obtained during the manufacture and ripening of functional and control cheeses. An experimental set-up was used to evaluate the detection threshold of free nucleic acids for extraction protocols based on pelleted microorganisms. To our knowledge, this straight-forward approach provides the first experimental evidence indicating that DNA is not a reliable marker of cell integrity, whereas RNA may constitute a more accurate molecular signature to estimate both bacterial viability and metabolic activity. Compositional analysis revealed that the bioactive molecules were effectively incorporated into the cheese matrix, at levels considered optimal to exert their biological action. The starter S. thermophilus was detected by qPCR and RT-qPCR during cheese production at the industrial level, from at least 30min after its inoculation until 81days of ripening, supporting the possible role of this species in shaping organoleptic profiles. We also showed for the first time that the addition of phytosterols at functional concentrations, not only did not affect starter performance but also correlated with a significant increase in target DNA and cDNA levels in most of the time points evaluated throughout cheesemaking. Therefore, these findings suggest that the growth and metabolism of S. thermophilus may be enhanced by the incorporation of these biologically active molecules during cheese production, providing important information for the industrial design of novel fermented foods. Fil: Pega, Juan Franco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Rizzo, Sergio Anibal. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Pérez, Carolina Daiana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Rossetti, Luciana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Díaz, Gabriela. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Ruzal, Sandra Mónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentina Fil: Nanni, Mariana Sandra. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Descalzo, Adriana Maria. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Centre de Coopération Internationale en Recherche Agronomique pour le Développement; Francia

An orange-colored pectin-enriched fraction previously obtained from discarded carrots (CPEF; 42%-methylated, 14%-acetylated, 50% uronic acids) through high-power-ultrasound and bacterial hemicellulase, carrying carotenes, lutein, and α-tocopherol, was evaluated as a food additive for its capacity to stabilize a model spreadable 20:80 w/w chia-oil-in-water emulsion. The optimal formulation for physical stability after 45 days at 25 °C was first determined through a Box-Behnken design with three independent variables (CPEF and Tween 80 concentrations, and ultrasound-emulsifying time). The optimized CPEF emulsion constituted a calcium-crosslinked “weak-gel type” network formed by the contribution of oil droplets. During storage, its elastic modulus increased probably by CPEF adsorption at the interface. In the optimized emulsion, CPEF prevented oil-phase oxidation by the air-oxygen entrapped, through the 45 day storage (peroxide index: 7.6meq/kg oil-phase; TBARS: 6.0 mg MDA eq/kg oil-phase), based on the differential partition of antioxidants between the interior of the oil droplets (apolar carotenes) and the oil-water interface (more polar tocopherol), the latter formed by the nonionic Tween 80 emulsifier. Despite unfavorable conditions for the preservation of food systems (water activity = 0.979; pH 5.4; air-oxygen; 25 °C), the emulsion orange-color was highly stable during storage due to the stability of carotenoids. CPEF is thus a useful functional additive for food preservation.

This work describes the formulation of a functional yogurt-like product based on fermented maize with added phytosterols and its oxidative stability during cold storage. The technological challenge was to stabilize 3.5% esterified phytosterols (between 2 and 3 g of free sterols) in a low-fat emulsion and to preserve the obtained product throughout processing and storage. The natural bioactive compounds: lutein, zeaxanthin, β-cryptoxanthin, β-carotene and γ-tocopherol were detected in the yogurt, and remained stable during 12 days of refrigeration. Higher content of C18:1 n-9 and C18:3 n-3 (six and ninefold, respectively) were obtained in samples with phytosterols. This was desirable from a nutritional point of view, but at the same time it induced lipid oxidation that was 1.4-fold higher in the product with phytosterols than in the controls. The use of a multivariate approach served to find descriptors which were related to treatments, and to explain their behavior over time. Fil: Descalzo, Adriana María. Instituto Nacional de Tecnología Agropecuaria; Argentina. Universidad de Morón; Argentina Fil: Rizzo, Sergio Aníbal. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Los Alimentos; Argentina. Universidad de Morón; Argentina Fil: Servent, Adrien. Centre de Coopération Internationale en Recherche Agronomique pour le Développement; Francia. Université de La Reúnion; Francia Fil: Rossetti, Luciana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Los Alimentos; Argentina Fil: Lebrun, Marc. Université de La Reúnion; Francia. Centre de Coopération Internationale en Recherche Agronomique pour le Développement; Francia Fil: Pérez, Carolina Daiana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Los Alimentos; Argentina Fil: Boulanger, Renaud. Université de La Reúnion; Francia. Centre de Coopération Internationale en Recherche Agronomique pour le Développement; Francia Fil: Mestres, Christian. Centre de Coopération Internationale en Recherche Agronomique pour le Développement; Francia. Université de La Reúnion; Francia Fil: Pallet, Dominique. Université de La Reúnion; Francia. Centre de Coopération Internationale en Recherche Agronomique pour le Développement; Francia Fil: Dhuique-Mayer, Claudie. Université de La Reúnion; Francia. Centre de Coopération Internationale en Recherche Agronomique pour le Développement; Francia

Fiber microparticles (MPCs) separately obtained from peel and pulp of Japanese plum residues contained co-extracted β-carotene, lutein, and α- and γ-tocopherols, as well as polyphenols (cyanidins, quercetin derivatives, pentameric proanthocyanidins). Peel and pulp MPCs were then separately evaluated as natural antioxidant additives (2.0% w/w level) in raw breast chicken patty, susceptible to oxidation. Their effect on technological properties was also analyzed. MPCs reduced in 50% the formation of thiobarbituric acid reactive substances (TBARS) in raw patties during 10-days storage at 4.0. °C. Ferric reducing power (FRAP) was 77-157% higher in MPCs-added patties, especially with peel MPCs, being then attributed to the antioxidants supplied by these MPCs. It can be also associated to the highest α- and γ-tocopherol levels found in the peel MPCs-added patties, which remained high after cooking as well. Also, higher pectin and low lignin contents of pulp MPCs determined greater hydration, stabilized the cyanidins and, hence, the red color transferred to raw patties, and increased springiness of cooked patties. Plum peel and pulp MPCs are efficient additives for chicken meat products. Fil: Basanta, Maria Florencia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rizzo, Sergio Anibal. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Szerman, Natalia. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Vaudagna, Sergio Ramon. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Descalzo, Adriana Maria. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Gerschenson, Lia Noemi. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pérez, Carolina Daiana. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rojas, Ana Maria Luisa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The effect of using increasing proportions of methylcellulose (MC) for the development of glycerol plasticized films based on high methoxyl pectin (HMP) (30:70, 50:50 and 70:30 w/w HMP:MC) and carrying L-(+)-ascorbic acid (AA) was studied with the purpose of achieving higher stability of AA and localized antioxidant activity at food interfaces. MC and 30:70 HMP:MC systems could not be casted. The shelf-life of the other AA-active films was assessed by storage at 25 C, constant relative humidity (RH: 33.3%, 57.7% and 75.2%) and vacuum conditions. The rate constant for AA hydrolysis increased with the RH and, hence, with water mobility. Browning and AA degradation rates were directly related. When stored at 75.2% RH, both decreased as MC proportion increased. Compared to HMP film, the highest proportion of MC (50:50 HMP:MC) showed the highest AA stabilization under vacuum and greater performance under air atmosphere. They also developed localized antioxidant activity preserving the tocopherol content of walnut oil. Fil: Perez, C. D.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina Fil: De'nobili, Maria Dolores. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rizzo, Sergio Anibal. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina Fil: Gerschenson, Lia Noemi. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Descalzo, Adriana Maria. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación de Agroindustria. Instituto de Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rojas, Ana Maria Luisa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

l-(+)-Ascorbic acid (AA) was compartmentalized into a low methoxyl pectin (LMP) film in view of localized antioxidant activity at food interfaces. The AA hydrolysis was specifically studied in the present work in order to determine the ability of the formulated LMP film to stabilize AA. Hence, films were stored at controlled relative humidity (RH) in the absence of air. A commercial LMP characterized by a 40% degree of methylesterification (DM) was used. Since sucrose is normally added for its standardization, films were also made with the dialyzed LMP in order to determine the sucrose effect. Glycerol was used for plasticization. Kinetics of AA loss and subsequent browning development were determined, which are dependent on the RH. Considerable AA retention (t1/2 = 744, 727, and 185 days) was achieved at 33. 3%, 57. 7%, or 75. 2% RH, respectively, at 25 °C. Browning rate constants decreased in one order of magnitude with respect to kinetic constants determined from films previously developed with high methoxyl pectin (HMP; DM of 73%). Absence of sucrose in the LMP network only affected the browning kinetics at 75. 2% RH. The glass transition temperature (Tg) decreased with the increment of moisture content of the films and in a similar degree (Tg ≈ -90 °C) to that observed for the HMP films, indicating the contribution of water to the network plasticization. However, water was more confined in the LMP network as inferred from the water availability determined by the 1H-NMR and DSC. This was attributed to the water interaction at the Ca2+ junction zones. Sucrose seemed to hinder the retention of water molecules by the polymeric network at 75. 2% RH. Fil: De'nobili, Maria Dolores. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pérez, Carolina Daiana. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Navarro, Diego Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; Argentina Fil: Stortz, Carlos Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; Argentina Fil: Rojas, Ana Maria Luisa. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina