Blueberries are a popular fruit in pies, juices and eaten as whole fresh berries. They are also gaining popularity as a source of antioxidants. Interested in the flavors that make something taste like blueberries, food scientists and researchers, such as Bett-Gerber et al., study blueberry composition. In 2013, this research group evaluated the taste of blueberries by developing a lexicon.1 Recently, they sought to determine what makes these berries so desirable by studying the chemical composition.2
For their investigation, Bett-Gerber et al. characterized six cultivars of southern highbush (SHB) and rabbiteye (RE) which represent two of the three main blueberry cultivars grown in the United States. The team harvested and pressed blueberries on two different days. The berries were frozen at -20 C, and then washed, thawed, and juiced. Each berry sample (50 mL) was presented to a sensory panel who evaluated the blueberry juice using 18 ﬂavor/taste/feeling attributes. Among the 18 attributes, the team saw correlations in composition and physicochemical data with blueberry, berry, strawberry, purple grape, floral, sweet aroma, sour aroma, sweet, bitter, sour, overripe fruit/straw and astringent flavors.
Next, they surveyed the organic acids in blueberry juice by performing ultra-high performance liquid chromatography (HPLC). For this analysis, the authors centrifuged and filtered blueberry juice. They then placed the juice in 10 mL autosampler vials (Thermo Scientiﬁc), sealed with Teﬂon lined silicon septa. They used an HPLC system consisting of an AS50 autosampler, a GP50 gradient pump and a PDA100 photodiode array detector controlled by Chromeleon software (Thermo Scientiﬁc) to analyze the samples.
Each sample was measured for sugars, acids, anthocyanidins, Folin-Ciocalteu, soluble solids (BRIX), titratable acidity (TA), and antioxidant capacity. They also surveyed the glucose, fructose, and sucrose in blueberry juice by high-performance anion exchange chromatography using a Dionex CarboPac PA1 analytical and guard column (Thermo Scientific).
This analysis revealed SHB blueberries were significantly greater in blueberry, strawberry, purple grape, floral, overripe fruit/straw, and sweet aroma flavors than RE blueberries. They also found the SHB berries were significantly greater in sweet taste. RE blueberries had greater intensities of bitter and sour tastes. Of the 3 cultivars of each type evaluated, there were intensity differences in the blueberry flavor between the 3 cultivars. They also saw differences in sweet, bitter, and sour taste in berries harvested 2 weeks apart.
Looking for correlations between flavor and chemical content, the team determined sweet taste positively correlated with glucose, total sugars, oxalic acid, citric acid, anthocyanidins, and BRIX. Meanwhile, it negatively correlated with sucrose, quinic acid, and total acids. Blueberry flavor, also correlated with oxalic acid, citric acid, and ORACFL. It negatively correlated with quinic acid and total acids. Sour taste correlated with total acids and TA, and negatively correlated with pH and BRIX:TA ratio.
The authors concluded that this work indicated polyphenols did not have a great impact on bitter and astringent in fresh pressed blueberry juices. Higher concentrations of polyphenols were connected with more intense sweet taste in some blueberry cultivars.
1. Bett-Garber KL, Lea JM. 2013. Development of ﬂavor lexicon for fresh pressed and processed blueberry juice. [PDF] J Sens Stud 28:161–70
2. Bett-Gerber, et al. (2015) “Flavor of Fresh Blueberry Juice and the Comparison to Amount of Sugars, Acids, Anthocyanidins, and Physicochemical Measurements”, Food Science, Volume 80, Issue 4, pages S818–S827, April 2015