Location: Children's Nutrition Research CenterTitle: Effect of postharvest handling practices on phytochemical concentrations and bioactive potential in wild blueberry fruit Author
Submitted to: Journal of Berry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2012
Publication Date: 12/15/2012
Citation: Gustafson, S.J., Yousef, G.G., Grusak, M.A., Lila, M.A. 2012. Effect of postharvest handling practices on phytochemical concentrations and bioactive potential in wild blueberry fruit. Journal of Berry Research. 2(4):215-227. Interpretive Summary: Wild blueberries contain a range of compounds with potential health benefits to humans. One group in particular is the group of compounds called polyphenolics. These compounds can serve as antioxidants or can help to reduce inflammation in people. Blueberries are a rich source of polyphenolics, especially when the fruit are freshly harvested. Because these polyphenolic compounds can be degraded by cooking or storage, we were interested in understanding how various handling or culinary practices might alter the concentrations of individual polyphenolics in wild blueberry fruit. Studies were conducted in which frozen blueberries were subjected to several freeze-thaw cycles to mimic potential temperature fluctuations encountered in retail sales, or in the home environment. Fruit were also subjected to baking, boiling, or microwaving to assess the effect of common cooking practices. The concentrations of individual polyphenolic compounds were reduced to some extent by all of these treatments, but only by a moderate amount. These studies are important because they help us understand how storage or cooking might alter the levels of health-beneficial compounds in wild blueberry fruit. Furthermore, they provide us with a true sense of the amounts of these health-beneficial compounds that one might be ingesting when consuming different blueberry-containing foods.
Technical Abstract: In this study, we quantified anthocyanin (ANC), proanthocyanidin (PAC), and chlorogenic acid (CA) concentrations in wild blueberry fruit (WBB) exposed to a variety of postharvest handling practices relevant to consumers and to industry. Additionally, we analyzed the bioactive potential of WBB subjected to common culinary preparations such as baking, boiling, and microwaving. Levels of ANC, PAC, and CA in individually quick frozen (IQF) WBB that had been subjected to temperature fluctuations, which are often encountered during distribution and handling for retail sales, dropped by approximately 8, 43, and 60%, respectively, compared to an IQF WBB composite that was stored continuously from harvest at -80 C. Baking IQF WBB reduced ANC, PAC, and CA concentrations by 11.2, 14.6, and 10.6%, respectively, and boiling decreased ANC, PAC, and CA concentrations by a minimum of 7.4, 14.4, and 36.8%, respectively. Microwaving IQF WBB for 1 minute increased ANC concentrations by 12.9% but exposure to 3 and 5 minutes resulted in significant decreases (29.8 and 81.6%, respectively). PAC concentrations in IQF WBB exposed to microwaves for 1, 3, and 5 minutes decreased by 14.3, 5.4, and 87.1%, respectively, whereas CA concentrations were not significantly impacted. At a concentration of 25 ug/ml, baked and boiled IQF WBB extracts maintained the ability to inhibit lipopolysaccharide (LPS)-induced ROS in SH-SY5Y cells. Extracts of WBB that were microwaved for 1 or 3 minutes retained bioactivity in our model for inflammation, while those microwaved for 5 minutes were unable to inhibit LPS-induced ROS.