RESUMO
Beneficial health effects are attributed to the wide array of polyphenols such as anthocyanins present in berries. Blackberries have been improved genetically to be cultivated in different climate such as Brazil. Thus, distinctive cultivars were created. However, antioxidant properties of these have not been evaluated. This study aimed to investigate the availability of phenolic compounds in Brazilian cultivar blackberries (cv. Xavante) after processing into purées, coulis and jam changes during storage. Physicochemical, total phenolic compounds (TPC), anthocyanins and antioxidant activity of frozen and processed food products were evaluated. The pH values of jam and frozen pulp increased to a greater extent during storage. Pureé A (70 °C for 20 min) showed the highest value for lightness and redness on day 1 with a decrease after 30 days of storage. Redness values decreased to a greater extent for purée A, indicating less stable product over time whereas coulis presented optimal stability shown by the smaller color difference value. No differences in TPC were observed for frozen pulp, purée A, purée B, and coulis. Significantly lower amount of TPC was present in the jam indicating degradation of phenolic compounds upon heating and concentration process involved in jam making. An increase in antioxidant activity (ABTS assay) was observed in processed products after storage, which might be related to the development of new compounds with greater antioxidant activity. Therefore, processing of blackberries into food products is an alternative to prolong the accessibility of those fruits without extensive loss of antioxidant activities.
RESUMO
An experiment was conducted to evaluate the conservation of blackberry, cv. Tupy, stored under refrigeration and coated with different edible coatings. Four treatments were carried out: control T1 (uncoated), T2 (chitosan 1.5 %), T3 (cassava starch 2.5 %) and T4 (kefir grains in water 20 %), stored at temperatures of 0 and 10 °C; 1.0 % (m/v) sorbitol/glycerol was added as plasticizers. Chemical and physical-chemical evaluations (weight loss, firmness, pH, titratable acidity, soluble solids, SS/TA ratio and anthocyanins) were made, besides rot incidence. The results showed that cooling to 0 °C combined with T2 showed an effect in reducing the physiological loss of weight (4.41 %), in retaining fruit firmness (19.1 N) and presenting lower incidence of rot (6.19 %). Likewise, in physical and chemical parameters: SS did not alter significantly during the whole period of 18 days of storage.
RESUMO
Esta revisão de literatura teve como objetivo abordar o controle do escurecimento enzimático de frutas e hortaliças minimamente processadas. A ação das enzimas polifenoloxidase (PPO) e peroxidase (POD), o papel dos substratos fenólicos e as alterações nutricionais e sensoriais resultantes dessa ação foram tratados nesse artigo, bem como os métodos de controle aplicáveis ao processamento mínimo de vegetais. Os estudos revisados evidenciaram que a PPO e a POD afetam negativamente a cor dos produtos minimamente processados , e também podem reduzir o seu valor nutricional. A forma mais eficiente de controlar esse problema é a combinação entre métodos físicos e químicos por evitar o uso de tratamentos individuais mais severos, que poderiam prejudicar a aparência e a textura dos vegetais. Avanços tecnológicos na conservação pós-colheita e a crescente procura por vegetais minimamente processados são determinantes para estimular a pesquisa aplicada para o controle do escurecimento enzimático, podendo resultar em menores perdas nesse segmento de mercado.
