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The incidence of chronic diseases increases with advancing age of the population. A commonly discussed cause of chronic diseases is oxidative stress, which occurs in the body when there is an imbalance between the formation and inactivation of so-called reactive oxygen species (ROS). Epidemiological data suggest that a 'healthy diet', with a high content of flavonoids indicates preventive properties and correlates with an inverse effect with respect to the risk of chronic diseases. Berries (especially bilberries, Vaccinium myrtillus L.) are an important source of these flavonoids. In this study, we investigated, in vitro, the antioxidative properties of fractions obtained from a commercially available anthocyanin-rich bilberry extract (BE). As markers for antioxidative activity, the intracellularly generated ROS levels, oxidative DNA damage, and total glutathione (tGSH) levels were determined in the human colon cell lines Caco-2 and HT-29. In Caco-2 cells, the ROS levels and, in both cell lines, the oxidative DNA damage, were significantly reduced in the presence of the original BE and phenolcarbonic acid-rich fraction. Total GSH levels were slightly increased after pretreatment with BE, phenolcarbonic acid and the polymeric fractions, but not with the anthocyanin fraction. In summary, the BE and the therefrom-isolated phenolcarbonic acid-rich fraction, showed the most potent antioxidative activity whereas the polymeric and anthocyanin-rich fraction, in total, were less active., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Anthocyanins are often associated with health benefits. They readily degrade during processing and storage but are also dependent on the matrix conditions. This study investigated how strawberry anthocyanins are affected by preservation technologies and a relatively protein-rich kale juice addition during storage. A strawberry–kale mix was compared to a strawberry–water mix (1:2 wt; pH 4), untreated, thermally, pulsed electric fields (PEF) and high-pressure processing (HPP) treated, and evaluated for anthocyanin stability and bioaccessibility during refrigerated storage. The degradation of strawberry anthocyanins during storage followed first-order kinetics and was dependent on the juice system, preservation technology and anthocyanin structure. Generally, the degradation rate was higher for the strawberry–kale mix compared to the strawberry–water mix. The untreated sample showed the highest degradation rate, followed by HPP, PEF and, then thermal. The relative anthocyanin bioaccessibility after gastric digestion was 10% higher for the thermally and PEF treated samples. Anthocyanin bioaccessibility after intestinal digestion was low due to instability at a neutral pH, especially for the strawberry–kale mix, and after thermal treatment. The storage period did not influence the relative bioaccessibility; yet, the absolute content of bioaccessible anthocyanins was decreased after storage. This research further presents that processing and formulation strongly affect the stability and bioaccessibility of anthocyanins during storage.

Anthocyanins are often associated with health benefits. They readily degrade during processing and storage but are also dependent on the matrix conditions. This study investigated how strawberry anthocyanins are affected by preservation technologies and a relatively protein-rich kale juice addition during storage. A strawberry–kale mix was compared to a strawberry–water mix (1:2 wt; pH 4), untreated, thermally, pulsed electric fields (PEF) and high-pressure processing (HPP) treated, and evaluated for anthocyanin stability and bioaccessibility during refrigerated storage. The degradation of strawberry anthocyanins during storage followed first-order kinetics and was dependent on the juice system, preservation technology and anthocyanin structure. Generally, the degradation rate was higher for the strawberry–kale mix compared to the strawberry–water mix. The untreated sample showed the highest degradation rate, followed by HPP, PEF and, then thermal. The relative anthocyanin bioaccessibility after gastric digestion was 10% higher for the thermally and PEF treated samples. Anthocyanin bioaccessibility after intestinal digestion was low due to instability at a neutral pH, especially for the strawberry–kale mix, and after thermal treatment. The storage period did not influence the relative bioaccessibility; yet, the absolute content of bioaccessible anthocyanins was decreased after storage. This research further presents that processing and formulation strongly affect the stability and bioaccessibility of anthocyanins during storage. [ABSTRACT FROM AUTHOR]

Due to health-beneficial effects of polyphenols, their stability and bioaccessibility in strawberry puree as influenced by processing (thermal, pulsed electric field (PEF), high pressure processing (HPP)) and by combination with relatively protein-rich vegetable juice (kale) was investigated. Soluble strawberry anthocyanins decreased in the presence of kale, in a processing-dependent manner, likely due to interactions with kale proteins. In the strawberry-water-system, polyphenols increased after processing due to increased extraction, especially after thermal and PEF, while in the mix anthocyanins increased especially after HPP and PEF. Anthocyanin structure affected the ratio of free anthocyanins after the interaction. During gastric digestion, an increase in bioaccessible anthocyanins was observed, while during intestinal digestion it strongly diminished. Thermal, PEF and formulation of the mix reduced soluble protein fractions, as observed by decreasing SDS-PAGE band intensity. The proteins were easily digestible and after 15 min of gastric digestion, no bands appeared with an increase in TCA soluble peptides. With the increase in health awareness and the changing on-the-go lifestyle, consumers demand convenient fruit and vegetable-based products with high nutritional and health-promoting content. Thus, utilization of alternative processing with minimal impact on the quality of fruit and vegetable juices is considered as a promising tool to deliver such high nutritional products, however, little is known about their effect on multi-component juice systems, where interactions between the different components can occur. Strawberries are the most commonly consumed berry type, delivering high quantities of polyphenols and therefore a representative polyphenol-rich model system. Kale is gaining increasing attention due to the nutritional profile, above others, it contains relatively (to other fruits and vegetables) high protein content, and therefore displays an interesting vegetable-based protein-rich model. A more in-depth understanding of the effect of alternative processing on polyphenol-protein interactions in these increasingly popular mixed systems (green smoothies) and the digestive fate of these potentially health-beneficial compounds is studied and provides new insights into designing functional products attractive for consumers. • Effect of thermal, PEF and HPP and formulation with kale on polyphenols was studied. • Soluble anthocyanins decreased in mixed system due to interactions with kale matrix. • Extent of interactions was polyphenol structure and preservation technology dependent. • During simulated gastric phase high anthocyanin bioaccessibility was observed. • Anthocyanin bioaccessibility decreased during the intestinal phase. [ABSTRACT FROM AUTHOR]