Shelf Life Stability and Nutrient Content of Vegetable Amaranth

Abstract

Poor storage and handling conditions causes over 30% losses in leafy vegetables after harvesting. To increase the shelf life of the vegetables during storage and handling, more efforts are being put forward as there are research gaps in knowledge and technology on the storage techniques of the vegetables. The main objective of the study was to find out the physico-chemical changes of vegetable amaranth, with the main focus on the variety Amaranthus dubius stored under low temperature as well as modified atmospheric packaging. The harvested leaves were initially stored in modified atmosphere bags and placed in the cold room at 5 °C, 10 °C, 15 °C and 25 °C and a relative humidity of 75% with 25 °C acting as the control. The vegetable was analysed to determine the Vitamin C, β -carotene, moisture content, respiration rates and visual appeal changes. The Vitamin C content of the fresh leaf amaranth was 41 mg/100g. The loss of ascorbic acid was much greater in samples stored at higher temperatures as compared to the samples stored at lower temperatures. The leaves stored at 25 °C lost Vitamin C content to 8 mg/100g after 4 days of storage whereas the leaves stored at 5 °C lost the Vitamin C content to 8 mg/100g after 23 days of storage. The study also found that control sample lost 88% of ascorbic acid in 4 days as compared to 55% loss at 5 °C after 23 days. Storage temperature significantly (P<0.05) influenced the amount of Vitamin C retained in the vegetables. The content of β -carotene in the fresh leaf amaranth vegetable was 61.4 µg/g. It was deduced that the loss in carotene was slightly greater at room temperature (25 °C) and decreased with decreasing storage temperatures. At the end of the storage, the retentions of Beta carotene were 6.86, 19.6, 26.14 and 31.53 µg/g at 25 °C, 15 °C, and 10 °C respectively. Storage temperature significantly (P<0.05) influenced the amount of β-carotene retained in the vegetables. Storing the vegetables for longer time at room temperature (25 °C) rapidly increases the respiration rates of the vegetables with leaves stored at 25 °C experiencing the highest respiration rate as compared to storage temperatures of 5 °C, 10 °C, 15 °C. These results indicate that the shelf life and marketing period of amaranth vegetable can be prolonged by maintaining quality attributes and external appearance. Better retentions of vitamin C and β-carotene can be achieved by storage at modified atmospheric storage at 5 °C. Farmers and supermarkets should use 5 °C and relative humidity of 75% for storage of amaranth leaves for better retention of vitamins, colour and visual appeal.