Effect of heat treatment and storage on anthocyanins levels in food plants

Abstract

Introduction: Anthocyanins, the polyphenolic plant pigments, have high antioxidant activity (AOA), reduce the risks of many pathological conditions in the human body. However, the wide medical and preventive use of anthocyanins is limited by their degradation during processing of plant raw materials. The objective of the work was to study the anthocyanins’ stability by spectrophotometric method during heat treatment and storage of vegetable and berry plants.Study objects and methods: Purple potatoes, eggplants, red cabbage, purple carrots, blue onions, red raspberries and blue honeysuckle were used in the study. Anthocyanins’ stability was determined by numerical values of extracts’ absorption spectra from the studied plants.Results and discussion: High stability indices of 0.623–0.986 were obtained for the anthocyanins of purple carrots, blue onion bulbs or red cabbage leaves whose main component is the antioxidant cyanidin with a relative AOA equal to 3.49. Low stability indices of 0.229-0.23 were obtained for anthocyanins of red raspberry berries and purple potato tubers containing pelargonidin or malvidin with 2.49–3.36 times lower relative AOA than for cyanidin. A regular correlation between stability and AOA of anthocyanins with a rank correlation coefficient of 0.91 (p<0.05) was established.It was established that during three months of storage in a domestic refrigerator, the content of anthocyanins in purple carrots and purple potatoes decreased by 10–15% of the initial one, and this decrease was 2-3 times greater when other studied plants were stored for 1.5–2 months.Conclusion: It is advisable to use the developed spectrophotometric methods in the express-analysis at selection of perspective plants for industrial cultivation as raw material for anthocyanin-containing herbal formulation.