Polyphenol content and antioxidant activity in dehydrated berries and apple juice

Fruit consumption has increased in the last decade mainly due to health benefits associated with fruits being a good source of antioxidants, soluble fiber, and an important addition to the diet for weight loss and promoting overall health. The high concentration of polyphenolic compounds (antioxidants) in fruits, for example, anthocyanins in blueberries and raspberries, and flavonoids and phenolic acids in apples make these fruits attractive items for consumers. However little is known about how different production and processing methods affect the concentration, distribution, and biological activity of these important micronutrients. Therefore, there is a need to study how methods such as juicing and dehydration could alter the nutritive as well and the physical and chemical properties of fruits and fruit products.;In this study, hot air (HAD), freeze drying (FD) and microwave-vacuum (MIVACRTM) drying and juicing were examined. The dielectric properties of blueberries and a model food of similar sugar and organic composition as blueberries were examined during model dehydration processes. Compositional variation in blueberries, particularly small changes in the organic concentration can have significant effects on dielectric loss factor and dielectric heating properties of a food during dehydration, which could affect retention of antioxidants. Both blueberries and raspberries were dehydrated by HAD, FD, MIVAC RTM and a combination of HA/MIVACRTM and the level of polyphenolic compounds, total antioxidant activity and affect on adipogenesis in vitro were determined. Antioxidant components were lost during dehydration, but a combination of HA/MIVACRTM or FD tended to result in greater retention of total polyphenols and anthocyanins. Berries dried by these two methods also tended to retain higher antioxidant activity. Dried raspberries reduced adipogenesis induction in 3T3-L1 preadipocyte cells.;Also, a small study on cultivation practices was conducted in which commercial apple juices from conventional or organic apple farming practices, with and without filtration or antioxidant addition was tested for antioxidant activity, and in vitro anticancer and inflammatory bowel disease inhibitory properties. Apple juice regardless of cultivation method, had high antioxidant activity and a positive effect on reduction of HCT116 (colon) and MDA-MD-231 (breast cancer cells) viability.