A practical and inexpensive alginate-based tool for semiquantitative detection of vitamin C in juices and beverages

Abstract

Background: Vitamin C is an essential nutrient for maintaining good health. However, vitamin C cannot besynthesized in the human body, and its bioavailability depends solely on dietary intake. InThailand,9.9% of adults are deficient in vitamin C. Therefore, development of a simple anduser-friendly test kit for determiningvitamin C levels in foods and beverages is needed.

Objectives: This study aimed to develop a rapid, practical, and low-cost semiquantitative test kit formeasuring vitamin C content in juices and commercial beverages.

Methods: Calcium alginate beads loaded with a starch–iodine complex (blue-colored beads) were used for vitamin C detection. In the presence of vitamin C, iodine molecules in the beads werereduced to iodide ions, and the blue beads became colorless. The reaction rate wasproportional to the vitamin C concentration. A total of 88 juice and beverage samples wereanalyzed, and vitamin C contents in those samples were categorized into four levels: very high, high, medium, andlow.

Results: Vitamin C levels werevery high in juices from Indian gooseberry, Chinese jujube, redguava,chili,and bell pepper; high in strawberry and guava juices; medium in kiwi and lemonjuices; and low in orange and melon juices. Among commercial beverages, vitamin C levels werehigh in fortified products but low in diluted fruit/vegetable juices and functional drinks. Importantly, the entiretesting procedure required only 5 minutes.

Conclusion: A quick, practical, and inexpensive test kit for semiquantitative detection of vitamin C in juicesand commercial beverages was successfully developed. This innovative tool could be beneficialfor health-conscious consumers who want to measure the content of vitamin C in their foods.