Determination and Comparative Study of Sugars and Synthetic Colorants in Commercial Branded Fruit Juice Products

Abstract

Fruit juice-based products are potentially high demanded products in Sri Lanka. The research was conducted to estimate the total sugar content in commercially available fruit juice products and to compare the suitability and efficiency of analytical methods: Lane and Eynon titration method and UV-Visible spectrophotometric methods. Further synthetic colorants in the products were identified and compared with the label information. A consumer survey was conducted to elicit information on consumer preference and knowledge on sugar content of the products. Based on the survey, consumers were more concerned about taste (37%), brand name (28%), price (28%), and nutrition value (7%), respectively. Awareness about the Recommended Dietary Allowance (RDA) of sugar, added sugar consumption, and risk of chronic diseases was 49%. Awareness on the color coding system of the products was 68%. The total sugar content of the fruit nectars was determined using both methods. The maximum total sugar level (18.38 g/100 mL) was observed by the titration method, while the maximum total sugar level (18.31 g/100 mL) was measured by the spectrophotometric method in wood apple (Limonia acidissima) nectar in brand No. “1.” The maximum sucrose content (10.57 g/100 mL) was observed in mango (Mangifera indica L.) nectar in the brand No. “1.” Total sugar contents of both tested methods were compared using SAS 9.0 (Randomized Complete Block Design, RCBD). There is no significant difference (P>0.05) between the two testing methods. In conclusion, the Lane and Eynon titration method was identified as the most effective method for analysis of the total sugar in fruit juice-based products. Based on the analysis of thin-layer chromatography (TLC), a majority of fruit nectar samples (57.14%) contained natural colorants, while 42.86% of total samples contained synthetic colorants. Labelling violation was done by the manufacturers, and the consumer awareness was high with the color-coding system. Continuous surveillance is recommended to minimize health risk related to high sugar consumption of the population.