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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.

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Tropical highland blackberry by‐product (BBP) has high amounts of polyphenols including ellagitannins (ET) and anthocyanins (ATC). Information of the effect of different operations on ET is scarce. In this study, pseudo‐first and first order kinetic models and response surface methodology were applied to optimize the extraction of polyphenols from BBP using ethanol, a food grade solvent. Retention of total polyphenols, ET and ATC was analyzed considering their contents before and after the application of thermal vacuum concentration, ultrafiltration, and spray drying. The optimal conditions for extraction were: a 3.4 solvent/BBP ratio, 57.1% ethanol, 60.0°C, and 120 min extraction time. Thermal vacuum concentration showed a higher retention of ET. A higher purity of ET was accomplished with ultrafiltration. These results provide the basis for further research on the development of a powder enriched with polyphenols, mainly ET, from BBP for food and pharmacological purposes. Practical applications Ellagitannins (ET) are a group of polyphenols found in tropical highland blackberries grown in Costa Rica, mainly in their seeds that are discarded as a by‐product (BBP) during blackberry processing. The production process of an ingredient with high amounts of ET has not been widely reported. In this study, modeling and optimization of an ethanolic extraction of polyphenols from BBP, and the effects of thermal vacuum concentration, ultrafiltration and spray drying on polyphenolic compounds were analyzed. This information will lead to further experiments on the effective recovery of ET in order to produce a nutraceutical product, which is not only complementary to the diet, but may also aid in the prevention and treatment of diseases, or an ingredient to be used in the production of functional foods.

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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 (m sucrose ) 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°C) for osmotic dehydration, coupled with high-temperature, short-time (HTST) heat treatments for product stabilisation.

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