Indian Journal of Traditional Knowledge Vol. 15(3), July 2016, pp. 417-424
Changes in phenolic contents and antioxidant capacity of bayberry (Myrica esculenta Buch. Ham. ex D. Don) and yellow Himalayan raspberry (Rubus ellipticus Smith) based health beverages Hare Krishna1, 3*, BL Attri1, Akhilesh Kumar1 & Nazeer Ahmed2 1
ICAR-Central Institute of Temperate Horticulture-Regional Station, Mukteshwar, Naintal-263 138, Uttarakhand, India; 2 ICAR-Central Institute of Temperate Horticulture, Srinagar, Jammu and Kashmir, India; 3 ICAR-Central Institute for Arid Horticulture, Beechwal, Bikaner-334 006, Rajasthan, India E-mails:
[email protected];
[email protected];
[email protected];
[email protected] Received 02 March 2015, revised 09 February 2016
Sufficient evidences of the health benefits of wild edible fruits and their proven role in human nutrition are available. A number of wild but potentially commercialized fruits are existing in Himalayan regions of India such as red fruited ‘bayberry’ (Myrica esculenta Buch. Ham. ex D. Don) and ‘Yellow Himalayan Raspberry’ (Rubus ellipticus Smith), are amongst highly valued edible fruits. It would be advantageous to assess the antioxidant properties of these plants for possible use in the elaboration of functional foods or for consideration as potential sources of natural antioxidants. In this study, total carotenoids, flavanol, total flavonoids, O-dihydric phenol, total phenolics and total antioxidant capacity (measured by CUPRAC method) of underutilized fruit crops bayberry and yellow Himalayan raspberry based health beverages (ready-to-serve, RTS) stored at 5±2 0C for 10 weeks, were investigated. After the first two weeks in refrigerated storage, the RTSs showed an increase in total phenolics and total antioxidant capacity. However, at the end of the 10-week storage period, all RTSs exhibited a significant decline in total phenolics and total antioxidant capacity. However, total carotenoids appeared to be less affected during storage compared with the other antioxidants. Keywords: Ready-To-Serve, Total carotenoids, Total anthocyanin, CUPRAC, Organoleptic evaluation IPC Int. Cl.8: C07, C07C 403/24, C09K 15/00, A61K 36/00
The chain of events instigated by free radicals in human body leads to weakening of immunological functions and speeding up of the ageing process. This has also been linked to the development of several diseases such as cataract, cancer, cardio-vascular diseases, etc.1,2. Numerous epidemiological studies have proven that a diet with a plenty of fruits and vegetables may result in low occurrence of such chronic diseases3. Health benefits of such foods are attributed mainly to the presence of some phytochemicals like vitamins, anthocyanins, polyphenols, flavonoids, etc., which are usually referred as antioxidants4. Besides commercial fruits, the consumption of wild and underutilized fruits are also gaining importance owing to their antioxidant contents and consequently health benefits5. Aim of studying such underutilized crops is their conservation as potential sources of antioxidants and agronomic advancement for —————— *Corresponding author
economic upliftment of the local farming community. Ample evidences of the health benefits of wild edible fruits and their proven role in human nutrition are available6. A number of wild but potentially commercialized fruits are available in Himalayan regions of India7. Of which, red fruited ‘bayberry’ (Myrica esculenta Buch. Ham. ex D. Don) locally known as ‘Kaphal’ and ‘Yellow Himalayan Raspberry’ (Rubus ellipticus Smith) commonly referred as ‘Hisalu’ are amongst highly valued edible fruits. It would be advantageous to assess the antioxidant properties of these fruits for possible use in the elaboration of functional foods or for consideration as potential sources of natural antioxidants8. Berries are one of the most important dietary sources of phenolic compounds, including anthocyanins, phenolic acids, flavonol glycosides and flavan-3-ols9. Besides, berry phenolics may also act as antimicrobials which may be of help in the control of the wide spectra of pathogens, in view of recent problems associated with antibiotic resistance1.
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Phenolic compounds derived from fruits have received more and more attention in recent years because of their bioactive functions10. Bayberry juices from the red cultivars might be potential resources for the development of antioxidant functional drinks9. Bayberry is a rich source of anthocyanin, flavonoids and phenolic acids11. Despite being potentially rich in antioxidants, both bayberry6 and yellow Himalayan raspberry12 could not be popularized among the growers uptil now; perhaps, due to their poor shelf life, which can be attributed partly to the lack of epicarp protection and ripening during summer seasons9. One of the possible ways to popularize the cultivation of such underutilized fruits could be the development of technology for value addition through processing13, which in turn would also help regulate the availability of such antioxidant rich sources for consumption for a longer duration. The antioxidant properties of fruits may be modified by environmental and postharvest factors including processing and storage14. The objectives of the present investigation were to design alternative use of such underutilized fruits, other than the fresh consumption, by developing new antioxidant rich health beverages and to investigate the antioxidant properties of processed products stored at 5±2 C for 10 weeks. Assessment of the content of various antioxidants of these underutilized fruits is important in order to better identify the overall nutritional value and to encourage the increased consumption by the general public13. Bayberry has dark coloured fruits, while yellow Himalayan raspberry has attractive yellow fruits, which are potentially good sources of anthocyanin and carotenoids, respectively. Diversity in the type of antioxidants is viewed better3 and; therefore in the present study, we have also attempted blending of bayberry and Himalayan raspberry juices to prepare a more balanced drink in terms of antioxidant contents. Materials and methods Fresh fruits of bayberry (Kafal) and yellow Himalayan raspberry (Hisalu) were collected from forest area of Mukteshwar, District-Nainital, Uttarakhand, India which is situated at 2250 m above mean sea level. Preparation of ready-to-serve (RTS) beverages After proper washing, cleaning and sorting of bayberry (Kafal) and yellow Himalayan raspberry (Hisalu) fruits, juice was extracted through an electronic juicer (Philips, India). Fruit juices were
added @ 100 ml/ L of finished product. The required acidity in ready-to-serve (RTS) was adjusted with citric acid. No preservative was added to the prepared product. Final RTS characteristics were adjusted to 0.3 % acidity and 13 % TSS. Soluble solid content, titratable acidity, reducing and total sugars and pH Brix was measured at 20 °C using an Abbe refractometor (Atago, Tokyo, Japan). Titratable acidity, reducing and total sugars were estimated as per the method suggested by Ranganna15. The pH of the beverages was assessed using a pH meter (Inolab pH 730, Merck Specialities Pvt. Ltd., India). Estimation of ascorbic acid, total carotenoids and total anthocyanin The ascorbic acid and total carotenoids contents of the samples were estimated according to Ranganna15. Results were expressed on mg/ 100 ml. The total monomeric anthocyanin content was determined by the pH-differential method suggested by Giusti & Wrolstad16. The pigment content was calculated and expressed as mg cyaniding 3-glucoside (Cyd 3-glu) per L, using an extinction coefficient (Є) of 26,900 L/cm/mol and a molecular weight of 449.2 gmol/L. Determination of total flavonoids, flavanols and total phenolics content The estimation of total flavonoids was performed according to Wang et al.17. Results were expressed as mg of querecetin equivalents/100 ml. The quantification of flavanols was made by the method suggested by Thimmaiah18. The results were expressed as mg phloroglucinol equivalents/ 100 ml. Total phenolic content was quantified spectrophotometrically employing Folin–Ciocalteu reagent and results expressed as gallic acid equivalents (mg GAE/100 mL)19. Antioxidant activity (Cupric reducing antioxidant capacity, CUPRAC) CUPRAC assay was carried out by the method described by Apak et al.20 using copper (II) chloride, neocuproine and ammonium acetate buffer solutions. The antioxidant activity was expressed as mmol Trolox®/ litre, or mM TE/L. Organoleptic evaluation for acceptability of the RTSs Organoleptic evaluation was performed on beverage preparations by a ten-member trained panel.
KRISHNA et al.: CHANGES IN ANTIOXIDANT PROPERTIES OF FRUIT BEVERAGES
For each sensory parameter, such as colour and appearance, body or texture, flavour, taste and overall acceptability, 100 marks were allotted and the products were given to the panelist in coded form21. The panelists washed their mouths with water intermittently to evaluate samples. Significant differences were determined at the (P
