Impact of processing on the nutritional and functional value of mandarin juice

Although phenolic compounds have a role in the health benefits of fruit juice consumption, little is known about the effect of processing on their bioaccessibility. The release of phenolic compounds from the food matrix during digestion is an important pre-requisite for their effectiveness within the human body, and so it is fundamental to identify technological treatments able to preserve not only the concentration of phytochemicals, but also their bioaccessibility. In the present study, we investigated the impact of high-pressure homogenization (HPH), alone and in the presence of 100 g kg^-1 trehalose or Lactobacillus salivarius, on the bioaccessibility of flavonoids in mandarin juice. In addition, digested mandarin juices were supplemented to liver cultured cells in basal and stressed conditions to evaluate their protective effect in a biological system.

HPH reduced the concentration of total phenolics and main flavonoids but increased their bioaccessibility after in vitro digestion (P < 0.001). In the basal condition, supplementation with all digested juices significantly reduced intracellular reactive oxygen species (ROS) concentration (P < 0.001). Thiobarbituric acid reactive substances concentration in the medium was also reduced by supplementation with HPH-treated juices. Although pre-treatment with juices did not completely counteract the applied oxidative stress, it preserved cell viability, and cells pre-treated with juices submitted to HPH in the presence of probiotics showed the lowest ROS concentration.

The present study represents an important step ahead in the evaluation of the impact of processing on the nutritional and functional value of food, which cannot simply be assessed based on chemical composition. © 2020 Society of Chemical Industry.