Cultivar Evaluation and Effect of Fermentation on Antioxidant Capacity and in Vitro Inhibition of α-Amylase and α-Glucosidase by Highbush Blueberry (Vaccinium corombosum)

Abstract

The berry fruits of highbush blueberry (Vaccinium corymbosum) contain bioactive compounds with potential health benefits. The objective was to evaluate blueberries grown in southern Illinois as well as the effect of fermentation, at two different temperatures, on chemical and physical parameters. Fruits from fifteen blueberry cultivars were analyzed. Fruit diameter ranged from 12.8 mm to 18.7 mm, pH from 2.6 to 3.7, reducing sugars from 6.4% to 15.2%, total sugars from 13.9% to 21.6%, total polyphenols from 0.39 to 1.00 mg gallic acid equivalents (GAE)/g blueberry and antioxidant capacity from 5.8 to 10.9 μM Trolox equivalents (TE)/g. In vitro α-amylase and α-glucosidase inhibitory capacity relative to the positive control acarbose, a known anti-diabetic drug, showed a range from 91.8 to 103.3% for α-amylase and from 103.2% to 190.8% for α-glucosidase. Wines prepared from several of these blueberry cultivars were analyzed throughout fermentation and compared at room temperature and cold temperature fermentation for pH (3.5 to 6.3), °Brix (13.6 to 29.7), total polyphenols (375.4 to 657.1 μg GAE/mL wine), and antioxidant capacity (4.5 to 25.1 mM TE). The wines were also tested for their in vitro capacity to inhibit α-amylase and α-glucosidase and maintained similar inhibitory action as the berries. Highbush blueberry cultivars and their fermented beverages are good natural sources of antioxidants and starch-degrading enzyme inhibitors important for type 2 diabetes management.

Antidiabetic effects of natural plant extracts via inhibition of carbohydrate hydrolysis enzymes with emphasis on pancreatic alpha amylase

“…In some studies, the alpha-amylase inhibitory activity of berry extracts has been proposed as a possible mode of action for the glycaemic control. Thus, fifteen blueberry cultivars of Vaccinium corombosum (75) have shown in vitro alpha-amylase inhibitory activities ranging from 91.8 to 103.3 %, which correlates well with the total phenolic content of the cultivars (r= 0.85). In other study, polyphenol-rich extracts of diverse berries were tested against alpha-amylase enzyme showing that raspberries (Rubus idaeus) and rowanberries (Sorbus aucuparia) were the most effective ones (IC 50 values of 4.5 and 21.0 µg of gallic acid equivalent/ml).…”

Phenolic bioactives from developmental stages of highbush blueberry (Vaccinium corymbosum) for hyperglycemia management using in vitro models

“…However, yellow raspberry fruit had better inhibitory activity than red raspberry fruit (Cheplick et al 2007). Blueberry proanthocyanidins had higher a-glucosidase inhibitory activity than blueberry anthocyanins (Johnson et al 2011). Ellagic acid and catechin were identified as active inhibitors of a-glucosidase along with several specific anthocyanins in ripe raspberry fruit (Zhang et al 2010).…”

“…Pharmaceutical drugs currently used in diabetes management, can cause gastrointestinal side effects due to excessive a-amylase inhibition (Bischoff et al 1985). Many phenolic metabolites from plantbased food showed a-amylase and a-glucosidase inhibitory activity in in vitro studies, and offer better strategy to manage type 2 diabetes without potential harmful side effects (McDougall et al 2005;Grussu et al 2011;Johnson et al 2011). Foods naturally rich in these phenolics have the potential to provide simple dietary strategies to regulate early stages of hyperglycemia.…”

Prospecting Antioxidant Capacities and Health-Enhancing Phytonutrient Contents of Southern Highbush Blueberry Wine Compared to Grape Wines and Fruit Liquors

“…Besides the specific cultivar of Elliot and Weymouth, most blueberry wines were produced from mixed cultivars. For example, Johnson et al (2011) used 15 cultivars including Berkley, Blue Chip and Blue Haven, while in this study, the mixed cultivars were, as mentioned earlier, Star, Windsor, Emerald, Primadonna and Jewel.…”

“…Su and Chien (2007) reported that the blueberry wine making process did not really lower the anthocyanin content. There are only a few studies that have quantified the antioxidant capacity, anthocyanins and total phenols in blueberry wines, e.g., Sanchez-Moreno et al (2003), Su and Chien (2007) and Johnson et al (2011). However, no analytical quantification of the foregoing antioxidant activity and phytonutrients was found in literature for the Southern highbush blueberry wine.…”