An Investigation into the Antioxidant Content of Fresh, Frozen, Over-ripe and Homogenised Raspberries and Blueberries.

Abstract

The use of nutraceuticals as an alternative to pharmaceuticals is becoming increasingly common in today’s society. Fruits, including berries, contain many beneficial components proven to reduce the risk of developing chronic, non-transmissible diseases such as heart failure and type II diabetes. These most commonly include antioxidants which are found in high quantities in berries. As well as being popular within the general public for their taste, blueberries and raspberries are considered to be super-fruits due to their high antioxidant content. Blueberries and raspberries, amongst other fruits are commonly used to make smoothies as an easier way for the population to intake the recommended 5 portions of fruit or vegetables a day. There has been limited research conducted on the effects of homogenising fruits on their antioxidant content and the effects of different storage methods on antioxidant content remain to be truly stated. Methods: A wide range of methods were used to determine the quantities of some of the many different health-benefiting chemical components of blueberries and raspberries within this study. This includes the Benzie and Strain (1996) method of determining the Ferric Ion Reducing Antioxidant Power (FRAP) of the chosen berries. The Singleton and Rossi (1965) method of determining the total phenolic content of the berries and pH was measured and compared between each sample group. Total anthocyanin concentration was determined through a method described by Tashtoush et al (2016), and finally, a method described by Dere et al (1998) was used to determine the total chlorophyll content of the samples. Results: Statistical significance was seen in many of the result groups, although were inconsistent. Overall, blueberries were found to be higher in antioxidants and other health benefiting compounds than raspberries. However, raspberries were found to have a higher total phenolic content across treatment groups in comparison to blueberries. Conclusion: Homogenisation did not seem to have a consistent positive or detrimental effect on the antioxidant content of any of the berry groups. There were no consistent significant results found implying that freezing or leaving berries to ripen had any major effect on their antioxidant content. Future studies should focus on identifying individual antioxidants within berry samples through the use of HPLC, whilst also being conducted over a greater period of time to ensure chemical changes in groups can be seen. Key Words: Antioxidants, Polyphenolics, Raspberries, Blueberries, Storage Conditions