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Background: The stability of anthocyanins and colour of aqueous extracts from roselle (Hibiscus sabdariffa L.) was investigated during storage at 4-45 °C. The effect of the extraction procedure (cold or hot extraction with or without pasteurisation) on the kinetic behaviour was determined., Results: Data analysis showed first-order kinetics for the evolution of anthocyanin content, colour density, colour strength and browning index. Three models (Arrhenius, Eyring and Ball) were used to represent the temperature dependence of the reaction rates. The three models allowed the prediction of colour modifications according to the storage temperature over 6 months. Activation energies ranged from 22 to 26 kJ mol(-1) for anthocyanin degradation and from 18 to 34 kJ mol(-1) for colour parameter modification. The degradation rate during storage depended on the extraction procedure. When heated, the extracts were clearly less stable. Their colour changed faster during storage especially when hot water and pasteurisation were used., Conclusion: Although the anthocyanin content and initial colour were not modified, the extraction conditions, especially temperature, greatly affected the stability of the extracts during storage. Further studies are needed to understand the mechanisms involved., (Copyright © 2011 Society of Chemical Industry.)

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.

Anthocyanin stability was assessed over temperatures ranging from 30 to 90 degrees C for seven products: blood orange juice [Citrus sinensis (L.) Osbeck]; two tropical highland blackberry juices (Rubus adenotrichus Schlech.), one with high content and the other with low content of suspended insoluble solids (SIS); and four roselle extracts (Hibiscus sabdariffa L.). The blackberry juice showed the highest content of anthocyanins with 1.2 g/L (two times less in the roselle extracts and 12 times less in the blood orange juice). The rate constant for anthocyanin degradation and isothermal kinetic parameters were calculated according to three models: Arrhenius, Eyring, and Ball. Anthocyanins in blood orange juice presented the highest rate constant for degradation, followed by the blackberry juices and roselle extracts. Values of activation energies were 66 and 37 kJ/mol, respectively, for blood orange and blackberry and 47-61 kJ/mol for roselle extracts. For the blackberry juices, a high SIS content provided only slight protection for the anthocyanins. The increasing content of dissolved oxygen, from 0.5 to 8.5 g/L, did not significantly increase the rate constant. For both isothermal and nonisothermal treatments, all three models accurately predicted anthocyanin losses from different food matrices.

BACKGROUND: Blackberries have a high content of bioactive compounds such as anthocyanins and ellagitannins, which are associated with health benefits against cardiovascular diseases, cancer, diabetes, and other inflammatory conditions. OBJECTIVE: This study evaluated the effect of a tropical highland blackberry (Rubus adenotrichos Schltdl.) beverage (50% v/v) on lipids, glucose and antioxidant parameters of healthy individuals. METHODS: Thirteen healthy individuals of both sexes were assigned into two groups in a randomized crossover design. Each participant was subjected to a high fat and high carbohydrate diet challenge and drank 250 mL of either blackberry beverage or water with every meal, three times a day for 14 days. Total cholesterol, triglycerides, LDL cholesterol, HDL cholesterol, glucose level, superoxide dismutase (SOD), and catalase (CAT) enzymatic activities were assessed from plasma. RESULTS: Plasma levels of triglycerides, total cholesterol, and glucose levels significantly decreased (p < 0.05) after consuming the blackberry beverage. Changes in LDL and HDL cholesterol levels were not statistically significant (p > 0.05). CAT and SOD enzymatic activities increased slightly, although not statistically significant (p > 0.05). CONCLUSION: Drinking a beverage from a blackberry micro-filtered juice improved plasma lipid and glucose profiles, as well as CATand SOD enzymatic activities in healthy participants. [ABSTRACT FROM AUTHOR]

Summary: Slices (1.5 mm thick) of green papaya were impregnated through osmotic dehydration with a blackberry juice–sucrose solution to produce an intermediate moisture product. The effect of processing temperature (T) and sucrose‐added molality (msucrose) on mass transfer during the operation was assessed, using a response surface methodology (RSM). The RSM was used to model water loss, sugar and anthocyanin gain during the process. Increasing sucrose molality resulted in increasing water loss and sugar gain, but decreasing anthocyanin gain. Water transfer therefore limits anthocyanin impregnation, but not sucrose incorporation. Afterwards, the impact of heat treatment at high temperatures was analysed, using numerical simulation. The conditions of the combined process, designed to achieve an anthocyanin‐rich final product, are low sucrose‐added molalities (sucrose molality < 1 mol kg–1) and high processing temperatures (T > 50 ºC) for osmotic dehydration, coupled with high‐temperature, short‐time (HTST) heat treatments for product stabilisation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Blackberry fruits have recently gained attention because of their considerable amounts of polyphenols. OBJETIVE: The aim of this study is to compare the physicochemical composition and contents of the main polyphenolic compounds of nine tropical highland blackberry genotypes grown in Costa Rica, and to evaluate the effect of environmental conditions and farming practices on physicochemical composition of fruits of 'Wine red thorn', which is the most widely grown blackberry genotype in Costa Rica. METHODS: Nine blackberry genotypes were harvested at fully ripe stage. Environmental conditions (geographic location and harvest season) and farming practices (organic and conventional techniques) were evaluated to determine their effects on physicochemical composition and polyphenolic compounds of 'Wine red thorn' blackberries. Anthocyanins and ellagitannins contents were determined by HPLC-DAD. RESULTS: The tropical highland blackberries contained appreciable levels of polyphenols. Anthocyanin content ranged from 2.9±0.1 to 12±1 g cyanidin-3-glucoside equivalents/kg dry weight (DW); ellagitannin content ranged from 9.3±0.8 to 47±3 g ellagic acid equivalents/kg DW. The influence of environmental conditions and farming practices on physicochemical characteristics of 'Wine red thorn' blackberries was significant (p < 0.05). Blackberries harvested during the dry season had higher contents of sugars and anthocyanins than blackberries harvested during the rainy season. Organic blackberries had higher levels of ellagitannins than conventionally grown fruits. CONCLUSIONS: These data prove that Costa Rican blackberries are a good source of polyphenolic compounds, especially ellagitannins. Environmental and farming conditions can be exploited to obtain high quality blackberry fruits. [ABSTRACT FROM AUTHOR]

Nanofiltration membranes with molecular weight cut-off around 200 Da were evaluated to concentrate anthocyanins and ellagitannins in a blackberry juice. Temperature was 30°C and cross-flow velocity 0.3 m/s. Transmembrane pressures varied from 0.5 to 3 MPa. At volumetric reduction ratio (VRR) of 1, higher transmembrane pressures caused an increase of permeate flux and of retention of total anthocyanins (>94%) and total soluble solids (44-97%). Every membrane presented 100% of total ellagitannin retention. Results were represented using the solution-diffusion model. NF270 membrane at 3 MPa showed the highest potential for concentration of blackberry's main polyphenolic compounds (highest permeate flux and solute retention). Nevertheless, a simulated increase of VRR showed that permeate flux declined as the concentration of the feed solution increased. NF270 membrane may also be of interest to deacidify the juice, since at high pressures, sugars were completely retained and retention of acids was under 90%. Practical Applications The concentration of phytochemicals by means of membrane technologies is of interest to the food industry, because the operations replace evaporation processes that are energy-intensive and use high temperatures that can reduce the compounds' bioactivities. The results presented in this study may be valuable for processors that aim to concentrate fruit juices and extracts enriched with phytochemicals (such as anthocyanins and ellagitannins), by using nanofiltration. Furthermore, results show that nanofiltration membranes at specific operating conditions may not only be employed to concentrate, but also to deacidify fruit juices and extracts. This operation provides advantages when compared to other technologies such as calcium salt precipitation, ion-exchange resins and electrodialysis. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of mechanical and enzymatic pretreatments on the extraction of anthocyanins and ellagitannins from blackberries. Continuous pressing yielded significantly higher turbidity values and content of anthocyanins and ellagitannins ( P < 0.05) compared with discontinuous pressing. The use of enzymatic pretreatment also significantly increased the extraction of polyphenolic compounds ( P < 0.05), in particular that of total ellagitannins, on average from 437 to 982 mg ellagic acid equivalents/100 g (dry basis) when using discontinuous pressing. When microfiltration was used, the content of ellagitannins and anthocyanins was found to be similar in both feed and permeate when discontinuous press was used to extract the juice, but a significant decrease of 34% (dry basis) was found in the concentration of ellagitannins when continuous pressing was used ( P < 0.05). These results should be useful for future efforts to increase the extraction of polyphenolic compounds from fruits and vegetables. Practical Applications Blackberries have high contents of potentially bioactive polyphenolic compounds, mainly anthocyanins and ellagitannins. Therefore, processes must be optimized not only to obtain large amounts of juice from this fruit, but also to efficiently extract the compounds of interest. The methodology and results presented in this study should be beneficial for processors that aim to increase the recovery of potentially bioactive polyphenolic compounds from fruit using mechanical and enzymatic pretreatments. Furthermore, this study evaluated the potential of cross-flow microfiltration as a viable operation for cold stabilization of blackberry juice, while obtaining acceptable permeate flux and membrane retention of the compounds of interest. It is envisioned that this technology could be used in the same manner to ensure the microbiological stability of polyphenolic-enriched fruit juices and extracts. [ABSTRACT FROM AUTHOR]

Highlights: [•] Separation of ellagitannins by ultrafiltration (UF) was tested in blackberry juice. [•] Six organic plate and frame membranes (1–150kDa) were used from 0.5 to 3MPa. [•] Retention was 100% for ellagitannins and depended on pressure for anthocyanins. [•] Modeling confirmed interest in UF to purify ellagitannins through diafiltration. [Copyright &y& Elsevier]

Abstract: Ten nanofiltration flat-sheet membranes and eight tight ultrafiltration membranes with nominal MWCOs ranging from 0.2 to 150kDa were tested to concentrate anthocyanin extract from roselle. A pilot system was used, which featured a membrane cell with an effective area of 0.0155m2. Permeate fluxes were recorded for transmembrane pressures between 0.5 and 3.0MPa, while keeping all other operating conditions constant (volumetric reduction ratio 1, 35°C). Retention values of total soluble solids, acidity and anthocyanins increased with transmembrane pressure. With similar permeate fluxes at average transmembrane pressure, retention of anthocyanins is significantly higher for nanofiltration membranes than for ultrafiltration membranes. A membrane was then selected for an industrial trial on the basis of its flux, retention of compounds of interest and energy consumption per liter of permeate. The trial using a 2.5-m2 filtration surface, could concentrate roselle extract from 4 to 25g total soluble solids per 100g, with 100% retention of anthocyanins. No significant damages were observed when comparing concentrate quality with the initial roselle extract. [Copyright &y& Elsevier]

Abstract: Tropical highland blackberry (Rubus adenotrichus Schltdl.) is a good source of antioxidants and contains appreciable levels of phenolic compounds, mainly ellagitannins and anthocyanins. This study examined the influence of three ripening stages on phenolic contents. Major anthocyanin pigments increased from 0.20 (red fruit) to 1.34mgg−1 fresh weight (FW) (fully ripe fruit), whereas ellagitannins and ellagic acid derivatives dropped from 3.8 to 2.2mg ellagic acid equivalents g−1 (FW). Flavonols also dropped from 5.1 to 2.0mg quercetin equivalents 100g−1 (FW). Consequently, values for total phenolic compounds ranged from 5.8 to 5.2mg gallic acid equivalents g−1 (FW), showing no specific trend. Antioxidant activity (H-ORAC) increased from 38.29 to 64.00μmol of Trolox equivalents g−1 (FW) during ripening. When compared with other commercial cultivars, R. adenotrichus stands out for high H-ORAC value, although comparatively it possesses low anthocyanin content and average total phenolic content. [Copyright &y& Elsevier]

Abstract: The effect of water activity on anthocyanin degradation and non-enzymatic browning (NEB) indices was determined in a blackberry juice system heated to high temperature. Blackberry juice samples mixed with quartz sand at three different water activities (a w of 0.34, 0.76 and 0.95) and having the same concentration of anthocyanins (51±4mg100g−1 WB) were heated in a hermetically sealed reactor under non-isothermal conditions (100 to 140°C). Reaction kinetics were well-represented by first-order reaction models. A non-isothermal method was used for the identification of kinetic parameters, and the confidence interval for each parameter was determined via Monte-Carlo simulations. The estimated parameters revealed an increase in the anthocyanin degradation reaction rate constant (k ref ) from 0.9 to 3.5×10−3 s−1 as the water activity decreased from 0.99 to 0.34. The corresponding activation energies (E a ) for anthocyanins and NEB index were modified to a lesser extent by variations in water activity. Hence, the reduction of water activity had a negative effect on anthocyanin stability at high temperatures. [Copyright &y& Elsevier]

Abstract: Critical steps of a typical industrial line for processing a blackberry-based beverage in glass bottles have been studied, together with the effects of storage of final product at four different temperatures. For the steps, contents of total phenolics, anthocyanins, ellagitannins, and minor phenolic compounds were assessed by HPLC-DAD and antioxidant capacity by H-ORAC and DPPH. Thermal processes, especially blanching, drastically reduced anthocyanins, whereas hot-filling degraded ellagitannins. The final product showed reduced values for the anthocyanins cyanidin-3-glucoside (by 52%) and cyanidin-3-malonyl glucoside (64%), and ellagitannins lambertianin C (80%), and sanguiin H-6 (50%). Antioxidant capacity (H-ORAC) dropped by almost 47%. The anthocyanins and ellagitannins continued degrading during storage, especially if temperatures were high. Reduction kinetic parameters during storage were estimated for anthocyanins and, for the first time, for both lambertianin C and sanguiin H-6. [Copyright &y& Elsevier]