A.L. Molan1*, M. A. Lila2 and G. Ravindran
Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
* Corresponding author: Tel: +64-6-350 4799; Fax: +64-6-350 5446; E-mail address: A.L.Molan@massey.ac.nz
2College of Agriculture, Consumer and Environmental Sciences, University of Illinois at Urbana-Champaign, USA.
It is well known that the dietary intake of blueberries has a positive and profound impact on human health, performance,
and disease. The total phenolic contents (TPC), antioxidant and free radical-scavenging properties of aqueous extracts
prepared from the berries of two rabbiteye (Vaccinium ashei) and two highbush (V. corymbosum) genotypes of blueberry,
were studied in vitro. The results showed that for the highbush genotypes, extracts from the ‘Jersey’ cultivar had higher
TPC than extracts from ‘Dixi’ berries. Among the rabbiteye genotypes, ‘Tifblue’ had higher TPC than ‘Ono’. Antioxidant
and radical-scavenging activities among the rabbiteye and highbush genotypes were in accordance with the results of TPC
for all genotypes studied which indicates that the antioxidant activity is related to the TPC.
An animal model was used to assess the effects of orally administered aqueous berry extracts on the proliferation of
lactobacilli and bifidobacterial species and some undesirable bacteria in the caeca of rats. Gavaging rats with aqueous
extracts from inulin, ‘Ono’, ‘Tifblue’ and ‘Jersey’ genotypes but not ‘Dixi’ 3 times weekly for 4 weeks resulted in a
significant increase in the numbers of bifidobacteria while the extracts from all the genotypes but not from inulin were able
to significantly increase the numbers of lactobacilli in comparison with the control group gavaged with water. A
significant decrease in the numbers of bacteroides and clostridia was observed in the caeca of rats gavaged with the
blueberry genotypes when compared with the water-gavaged control rats. Moreover, rats gavaged with inulin, ‘Ono’,
‘Tifblue’, ‘Jersey’ and ‘Dixi’ showed 15.1%,10.5%, 21.9%, 22.9% and 5.6% reduction in the activity of β-glucuronidase
and 17.6%, 27.2%, 49%, 25.2% and 15.8% increase in the activity of β-glucosidase when compared to the control group
gavaged with water, respectively. In conclusion, significant differences were found in antioxidant/antiradical activities
and TPC among various genotypes of blueberries. Furthermore, we hypothesize that blueberry extracts could positively
modify the bacterial profile by increasing the numbers of beneficial bacteria and thereby improve gut health.