Ana Mercedes Pérez

Kinetics of anthocyanin degradation and browning in reconstituted blackberry juice treated at high temperatures (100-180°C).

Monomeric anthocyanin degradation and nonenzymatic browning (NEB) index have been determined in reconstituted blackberry juice heated at high temperature in a hermetically sealed cell. Statistical analysis demonstrated that, when the temperature range (100-180 degrees C) was divided into two subranges (100-140 and 140-180 degrees C) for anthocyanin degradation, reaction kinetics were well represented by two sequential first-order reactions. The activation energy for NEB from 100 to 180 degrees C (106 kJxmol(-1)) was slightly higher than the anthocyanin value at the lower temperature range (92 kJxmol(-1)), but was more than twice the value for the higher range (44 kJxmol(-1)). The reaction rate constant at 140 degrees C for anthocyanin degradation (3.5 x 10(-3) s(-1)) was two times that for the NEB index (1.6 x 10(-3) s(-1)). Hence, anthocyanin degradation was faster than the appearance of NEB products. The non-isothermal method developed allows estimating kinetic parameters and thereby generating temperature profiles of heat processes that would help preserve the nutritional properties of foods during high-temperature processes.

Osmosonication of blackberry juice: impact on selected pathogens, spoilage microorganisms, and main quality parameters.

UNLABELLED Osmosonication combines ultrasound with nonthermal concentration. It was applied on tropical highland blackberry (Rubus adenotrichus) juice over different periods of time to assess reductions in microorganism and the impact on main quality parameters. This juice had been inoculated with Salmonella spp., Shigella sp., a lactic acid bacterium, yeasts, and molds. It was then sonicated for 5.9 to 34.1 min at 20 kHz and 0.83 W/mL. Nonthermal concentration was simulated by mixing the juice with a concentrate to obtain 650 g TSS/kg. It was then stored at -18 °C for up to 82 h. The lactic acid bacterium, yeasts, and molds were reduced by 1.60 to as much as 5.01 log(10) CFU/mL, whereas, for pathogens, reductions were total ≥7.1 log(10) CFU/mL after 24 h of storage, even for juice not sonicated, because of low pH. Color, antioxidant capacity, anthocyanins, and ellagitannins did not change significantly during sonication treatment up to 32 min. However, an off-flavor was detected after 8 min of sonication. Nonetheless, osmosonication can be considered as an alternative to thermal processes for producing safe and high-quality concentrates. PRACTICAL APPLICATION Osmosonication represents a potential processing alternative for producing safe and high-quality concentrated fruit juice without applying thermal treatments. Findings reported in this article can also be applied by industries when concentrating juices by classical means at relatively low temperature. It provides industries with a mathematical model specific for blackberry juice, from which different combinations of sonication time and storage time of concentrate can be chosen to achieve safety and quality goals.

Novel Semiautomated Method for Assessing in Vitro Cellular Antioxidant Activity Using the Light-Scattering Properties of Human Erythrocytes

The novel method developed for screening cellular antioxidant activity relies on differences in light-scattering properties (turbidity) between intact and lysed human erythrocytes. AAPH, a peroxyl radical generator, was used to enhance lipid peroxidation. The consequent hemolysis triggered a loss of the light-scattering ability in the lysed erythrocytes. When an antioxidant was added, the area under the absorbance decay curve (AUC) was linearly proportional to the concentration of antioxidant compound. This erythrocyte cellular antioxidant activity (ERYCA) method was found to be relatively fast, sensitive, accurate, and repeatable, even when using erythrocytes from different donors and for different storage times. The method was used to assess the antioxidant capacity of pure phenolic compounds, fruit juices, stimulant beverages, and blood plasma and compared with ORAC values. The values resulting from the two methods did not correlate as the mechanisms involved were different.

Antioxidant and anti-inflammatory in vitro activities of phenolic compounds from tropical highland blackberry (Rubus adenotrichos).

This study evaluates the antioxidant and anti-inflammatory activities in a polyphenol extract from blackberries. The antioxidant activity measured via oxygen radical absorbance capacity (ORAC) was higher for the blackberry extract (4339 ± 144 μM TE/g) than for quercetin and ellagic acid. The blackberry phenolic compounds protected liposomes and liver homogenates against lipid peroxidation; in both models, the antioxidant activity (IC₅₀ = 7.0 ± 0.5 and 20.3 ± 4.2 μg/mL, respectively) was greater than that found with Trolox. The extract inhibited superoxide production by NADPH oxidase in THP-1 cells and nitrite production in J774A.1 cells stimulated with LPS+IFNγ, with nitrite production decreasing after 4 h of incubation with the extract, mainly through a strong scavenging activity. However, 24 h of treatment reduced the amount of nitrites (IC₅₀ = 45.6 ± 1.2 μg/mL) because of a down-regulation of iNOS protein expression, as demonstrated by Western blotting. The inhibitory activities found in blackberry phenols suggest a potential beneficial effect against oxidative stress and inflammatory processes.

Protective effect of tropical highland blackberry juice (Rubus adenotrichos Schltdl.) against UVB-mediated damage in human epidermal keratinocytes and in a reconstituted skin equivalent model.

Solar ultraviolet (UV) radiation, particularly its UVB (280–320 nm) spectrum, is the primary environmental stimulus leading to skin carcinogenesis. Several botanical species with antioxidant properties have shown photochemopreventive effects against UVB damage. Costa Ricas tropical highland blackberry (Rubus adenotrichos) contains important levels of phenolic compounds, mainly ellagitannins and anthocyanins, with strong antioxidant properties. In this study, we examined the photochemopreventive effect of R. adenotrichos blackberry juice (BBJ) on UVB‐mediated responses in human epidermal keratinocytes and in a three‐dimensional (3D) reconstituted normal human skin equivalent (SE). Pretreatment (2 h) and posttreatment (24 h) of normal human epidermal keratinocytes (NHEKs) with BBJ reduced UVB (25 mJ cm−2)‐mediated (1) cyclobutane pyrimidine dimers (CPDs) and (2) 8‐oxo‐7,8‐dihydro‐2′‐deoxyguanosine (8‐oxodG) formation. Furthermore, treatment of NHEKs with BBJ increased UVB‐mediated (1) poly(ADP‐ribose) polymerase cleavage and (2) activation of caspases 3, 8 and 9. Thus, BBJ seems to alleviate UVB‐induced effects by reducing DNA damage and increasing apoptosis of damaged cells. To establish the in vivo significance of these findings to human skin, immunohistochemistry studies were performed in a 3D SE model, where BBJ was also found to decrease CPDs formation. These data suggest that BBJ may be developed as an agent to ameliorate UV‐induced skin damage.

Use of response surface methodology to compare vacuum and atmospheric deep-fat frying of papaya chips impregnated with blackberry juice

ABSTRACT Vacuum and atmospheric deep-frying were employed to obtain blackberry-based snacks using unripe papaya as matrix. Papaya slices were osmotically impregnated with blackberry juice and fried between 126°C and 154°C at atmospheric pressure and between 110°C and 127°C under vacuum conditions. A response surface methodology (RSM) was used to define which responses (water activity, moisture and oil content, L*, C*, H*, hardness and degree of liking (DOL)) were significantly related to frying parameters (time and temperature). Then a principal component analysis (PCA) was applied to choose which ones related to DOL. PCA demonstrated that hardness and hue were the main drivers of liking for atmospheric frying, while for vacuum frying they were color and oil content. A second RSM was calculated to choose optimal processing conditions. Optimum conditions were 6 min at 117°C in vacuum frying and 6 min at 130°C and 3 min at 150°C in atmospheric pressure.

Physicochemical and antioxidant composition of fresh peach palm (Bactris gasipaes Kunth) fruits in Costa Rica

The variability of the physicochemical composition, carotenoid and polyphenol contents and hydrophilic antioxidant capacity of fresh peach palm (Bactris gasipaes) fruit was studied with a view to its exploitation as a potential source of bioactive compounds. The variability present in five batches of peach palm fruit obtained from two regions in Costa Rica: Tucurrique (T) and Perez Zeledon (PZ), was studied. Significant differences were found for fruit weight, length and width amongst the batches studied. The moisture, fat and protein contents of the Tucurrique fruit were significantly lower than those from Perez Zeledon. No significant difference in starch content was found between any of the batches of peach palm fruit studied. In terms of antioxidant compounds, the total carotenoid content ranged between 109 and 202 µg β-carotene equivalents/g dry weight (dw), while the total polyphenol content varied from 54 to 106 mg gallic acid equivalents (GAE) /100 g (dw). Both these components presented variability amongst the five batches. The antioxidant capacity was determined by the ORAC method and only the PZ 3 sample presented significant differences from the other four batches. The average hydrophilic antioxidant capacity was 37 ± 7 µmol of Trolox equivalents (TE)/g (dw). Overall, the peach palm fruit showed potential to be used in the development of functional foods since the variability of the raw peach-palm fruit, determined by applying a principal component analysis, showed that some characteristics of this fruit were not affected by harvest time and showed no differences between the batches from the two areas.A variabilidade da composicao fisico-quimica e do teor de carotenoides e polifenois, e a capacidade antioxidante hidrofilica da fruta fresca da pupunha (Bactris gasipaes) foram pesquisadas, a fim de avaliar o seu aproveitamento como uma fonte potencial de compostos bioativos. Estudou-se a variabilidade de cinco lotes de frutos da Costa Rica das regioes Tucurrique (T) e Perez Zeledon (PZ). Foram encontradas diferencas significativas para a massa, o comprimento e a largura entre os lotes. Os teores de umidade, gordura e proteina dos frutos de Tucurrique foram significativamente menores do que os teores dos frutos de Perez Zeledon. Nao foi encontrada diferenca significativa para o teor de amido entre todos os lotes de pupunheira estudados. Para os compostos antioxidantes, o teor de carotenoides totais variou entre 109 e 202 mg equivalentes β-caroteno / g de materia seca (ms), enquanto o teor de polifenois totais variou no intervalo de 54 a 106 mg de equivalentes de acido galico (GAE) / 100 g (ms). Ambos os compostos antioxidantes apresentaram variabilidade entre os cinco lotes. A capacidade antioxidante foi determinada pelo metodo ORAC e so a amostra PZ-3 foi significativamente diferente dos outros quatro lotes. A media da capacidade antioxidante hidrofilica foi de 37 ± 7 mmol de equivalentes de Trolox (TE) / g (ms). No geral, a fruta da pupunha apresenta potencial de utilizacao como ingrediente no desenvolvimento de alimentos funcionais, uma vez que a variabilidade da fruta da pupunha como materia-prima, determinada pela aplicacao de uma analise de componente principal, demonstrou que algumas das caracteristicas dessa fruta nao foram afetadas durante a epoca de colheita, e nenhuma diferenca foi encontrada entre os lotes das duas areas de estudo.

Composição físico-química de frutos de pupunha (Bactris gasipaes Kunth) na Costa Rica

The variability of the physicochemical composition, carotenoid and polyphenol contents and hydrophilic antioxidant capacity of fresh peach palm (Bactris gasipaes) fruit was studied with a view to its exploitation as a potential source of bioactive compounds. The variability present in five batches of peach palm fruit obtained from two regions in Costa Rica: Tucurrique (T) and Perez Zeledon (PZ), was studied. Significant differences were found for fruit weight, length and width amongst the batches studied. The moisture, fat and protein contents of the Tucurrique fruit were significantly lower than those from Perez Zeledon. No significant difference in starch content was found between any of the batches of peach palm fruit studied. In terms of antioxidant compounds, the total carotenoid content ranged between 109 and 202 µg β-carotene equivalents/g dry weight (dw), while the total polyphenol content varied from 54 to 106 mg gallic acid equivalents (GAE) /100 g (dw). Both these components presented variability amongst the five batches. The antioxidant capacity was determined by the ORAC method and only the PZ 3 sample presented significant differences from the other four batches. The average hydrophilic antioxidant capacity was 37 ± 7 µmol of Trolox equivalents (TE)/g (dw). Overall, the peach palm fruit showed potential to be used in the development of functional foods since the variability of the raw peach-palm fruit, determined by applying a principal component analysis, showed that some characteristics of this fruit were not affected by harvest time and showed no differences between the batches from the two areas.A variabilidade da composicao fisico-quimica e do teor de carotenoides e polifenois, e a capacidade antioxidante hidrofilica da fruta fresca da pupunha (Bactris gasipaes) foram pesquisadas, a fim de avaliar o seu aproveitamento como uma fonte potencial de compostos bioativos. Estudou-se a variabilidade de cinco lotes de frutos da Costa Rica das regioes Tucurrique (T) e Perez Zeledon (PZ). Foram encontradas diferencas significativas para a massa, o comprimento e a largura entre os lotes. Os teores de umidade, gordura e proteina dos frutos de Tucurrique foram significativamente menores do que os teores dos frutos de Perez Zeledon. Nao foi encontrada diferenca significativa para o teor de amido entre todos os lotes de pupunheira estudados. Para os compostos antioxidantes, o teor de carotenoides totais variou entre 109 e 202 mg equivalentes β-caroteno / g de materia seca (ms), enquanto o teor de polifenois totais variou no intervalo de 54 a 106 mg de equivalentes de acido galico (GAE) / 100 g (ms). Ambos os compostos antioxidantes apresentaram variabilidade entre os cinco lotes. A capacidade antioxidante foi determinada pelo metodo ORAC e so a amostra PZ-3 foi significativamente diferente dos outros quatro lotes. A media da capacidade antioxidante hidrofilica foi de 37 ± 7 mmol de equivalentes de Trolox (TE) / g (ms). No geral, a fruta da pupunha apresenta potencial de utilizacao como ingrediente no desenvolvimento de alimentos funcionais, uma vez que a variabilidade da fruta da pupunha como materia-prima, determinada pela aplicacao de uma analise de componente principal, demonstrou que algumas das caracteristicas dessa fruta nao foram afetadas durante a epoca de colheita, e nenhuma diferenca foi encontrada entre os lotes das duas areas de estudo.